text: /* Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /* Utility routines for Apache proxy */
  #include "mod_proxy.h"
  #include "ap_mpm.h"
  #include "scoreboard.h"
  #include "apr_version.h"
  #include "apr_hash.h"
  #include "proxy_util.h"
  #include "ajp.h"
  #include "scgi.h"
  
  #include "mod_http2.h" /* for http2_get_num_workers() */
  
  #if APR_HAVE_UNISTD_H
  #include <unistd.h>         /* for getpid() */
  #endif
  
  #if (APR_MAJOR_VERSION < 1)
  #undef apr_socket_create
  #define apr_socket_create apr_socket_create_ex
  #endif
  
  #if APR_HAVE_SYS_UN_H
  #include <sys/un.h>
  #endif
  #if (APR_MAJOR_VERSION < 2)
  #include "apr_support.h"        /* for apr_wait_for_io_or_timeout() */
  #endif
  
  APLOG_USE_MODULE(proxy);
  
  /*
   * Opaque structure containing target server info when
   * using a forward proxy.
   * Up to now only used in combination with HTTP CONNECT.
   */
  typedef struct {
      int          use_http_connect; /* Use SSL Tunneling via HTTP CONNECT */
      const char   *target_host;     /* Target hostname */
      apr_port_t   target_port;      /* Target port */
      const char   *proxy_auth;      /* Proxy authorization */
  } forward_info;
  
  /* Global balancer counter */
  int PROXY_DECLARE_DATA proxy_lb_workers = 0;
  static int lb_workers_limit = 0;
  const apr_strmatch_pattern PROXY_DECLARE_DATA *ap_proxy_strmatch_path;
  const apr_strmatch_pattern PROXY_DECLARE_DATA *ap_proxy_strmatch_domain;
  
  extern apr_global_mutex_t *proxy_mutex;
  
  static int proxy_match_ipaddr(struct dirconn_entry *This, request_rec *r);
  static int proxy_match_domainname(struct dirconn_entry *This, request_rec *r);
  static int proxy_match_hostname(struct dirconn_entry *This, request_rec *r);
  static int proxy_match_word(struct dirconn_entry *This, request_rec *r);
  static int ap_proxy_retry_worker(const char *proxy_function, proxy_worker *worker, server_rec *s);
  static proxy_worker *proxy_balancer_get_best_worker(proxy_balancer *balancer,
                                                      request_rec *r,
                                                      proxy_is_best_callback_fn_t *is_best,
                                                      void *baton);
  
  APR_IMPLEMENT_OPTIONAL_HOOK_RUN_ALL(proxy, PROXY, int, create_req,
                                     (request_rec *r, request_rec *pr), (r, pr),
                                     OK, DECLINED)
  
  PROXY_DECLARE(apr_status_t) ap_proxy_strncpy(char *dst, const char *src,
                                               apr_size_t dlen)
  {
      char *thenil;
      apr_size_t thelen;
  
      /* special case handling */
      if (!dlen) {
          /* XXX: APR_ENOSPACE would be better */
          return APR_EGENERAL;
      }
      if (!src) {
          *dst = '\0';
          return APR_SUCCESS;
      }
      thenil = apr_cpystrn(dst, src, dlen);
      thelen = thenil - dst;
      if (src[thelen] == '\0') {
          return APR_SUCCESS;
      }
      return APR_EGENERAL;
  }
  
  /* already called in the knowledge that the characters are hex digits */
  PROXY_DECLARE(int) ap_proxy_hex2c(const char *x)
  {
      int i;
  
  #if !APR_CHARSET_EBCDIC
      int ch = x[0];
  
      if (apr_isdigit(ch)) {
          i = ch - '0';
      }
      else if (apr_isupper(ch)) {
          i = ch - ('A' - 10);
      }
      else {
          i = ch - ('a' - 10);
      }
      i <<= 4;
  
      ch = x[1];
      if (apr_isdigit(ch)) {
          i += ch - '0';
      }
      else if (apr_isupper(ch)) {
          i += ch - ('A' - 10);
      }
      else {
          i += ch - ('a' - 10);
      }
      return i;
  #else /*APR_CHARSET_EBCDIC*/
      /*
       * we assume that the hex value refers to an ASCII character
       * so convert to EBCDIC so that it makes sense locally;
       *
       * example:
       *
       * client specifies %20 in URL to refer to a space char;
       * at this point we're called with EBCDIC "20"; after turning
       * EBCDIC "20" into binary 0x20, we then need to assume that 0x20
       * represents an ASCII char and convert 0x20 to EBCDIC, yielding
       * 0x40
       */
      char buf[1];
  
      if (1 == sscanf(x, "%2x", &i)) {
          buf[0] = i & 0xFF;
          ap_xlate_proto_from_ascii(buf, 1);
          return buf[0];
      }
      else {
          return 0;
      }
  #endif /*APR_CHARSET_EBCDIC*/
  }
  
  PROXY_DECLARE(void) ap_proxy_c2hex(int ch, char *x)
  {
  #if !APR_CHARSET_EBCDIC
      int i;
  
      x[0] = '%';
      i = (ch & 0xF0) >> 4;
      if (i >= 10) {
          x[1] = ('A' - 10) + i;
      }
      else {
          x[1] = '0' + i;
      }
  
      i = ch & 0x0F;
      if (i >= 10) {
          x[2] = ('A' - 10) + i;
      }
      else {
          x[2] = '0' + i;
      }
  #else /*APR_CHARSET_EBCDIC*/
      static const char ntoa[] = { "0123456789ABCDEF" };
      char buf[1];
  
      ch &= 0xFF;
  
      buf[0] = ch;
      ap_xlate_proto_to_ascii(buf, 1);
  
      x[0] = '%';
      x[1] = ntoa[(buf[0] >> 4) & 0x0F];
      x[2] = ntoa[buf[0] & 0x0F];
      x[3] = '\0';
  #endif /*APR_CHARSET_EBCDIC*/
  }
  
  /*
   * canonicalise a URL-encoded string
   */
  
  /*
   * Convert a URL-encoded string to canonical form.
   * It decodes characters which need not be encoded,
   * and encodes those which must be encoded, and does not touch
   * those which must not be touched.
   */
  PROXY_DECLARE(char *)ap_proxy_canonenc(apr_pool_t *p, const char *x, int len,
                                         enum enctype t, int forcedec,
                                         int proxyreq)
  {
      int i, j, ch;
      char *y;
      char *allowed;  /* characters which should not be encoded */
      char *reserved; /* characters which much not be en/de-coded */
  
  /*
   * N.B. in addition to :@&=, this allows ';' in an http path
   * and '?' in an ftp path -- this may be revised
   *
   * Also, it makes a '+' character in a search string reserved, as
   * it may be form-encoded. (Although RFC 1738 doesn't allow this -
   * it only permits ; / ? : @ = & as reserved chars.)
   */
      if (t == enc_path) {
          allowed = "~$-_.+!*'(),;:@&=";
      }
      else if (t == enc_search) {
          allowed = "$-_.!*'(),;:@&=";
      }
      else if (t == enc_user) {
          allowed = "$-_.+!*'(),;@&=";
      }
      else if (t == enc_fpath) {
          allowed = "$-_.+!*'(),?:@&=";
      }
      else {            /* if (t == enc_parm) */
          allowed = "$-_.+!*'(),?/:@&=";
      }
  
      if (t == enc_path) {
          reserved = "/";
      }
      else if (t == enc_search) {
          reserved = "+";
      }
      else {
          reserved = "";
      }
  
      y = apr_palloc(p, 3 * len + 1);
  
      for (i = 0, j = 0; i < len; i++, j++) {
  /* always handle '/' first */
          ch = x[i];
          if (strchr(reserved, ch)) {
              y[j] = ch;
              continue;
          }
  /*
   * decode it if not already done. do not decode reverse proxied URLs
   * unless specifically forced
   */
          if ((forcedec || (proxyreq && proxyreq != PROXYREQ_REVERSE)) && ch == '%') {
              if (!apr_isxdigit(x[i + 1]) || !apr_isxdigit(x[i + 2])) {
                  return NULL;
              }
              ch = ap_proxy_hex2c(&x[i + 1]);
              i += 2;
              if (ch != 0 && strchr(reserved, ch)) {  /* keep it encoded */
                  ap_proxy_c2hex(ch, &y[j]);
                  j += 2;
                  continue;
              }
          }
  /* recode it, if necessary */
          if (!apr_isalnum(ch) && !strchr(allowed, ch)) {
              ap_proxy_c2hex(ch, &y[j]);
              j += 2;
          }
          else {
              y[j] = ch;
          }
      }
      y[j] = '\0';
      return y;
  }
  
  /*
   * Parses network-location.
   *    urlp           on input the URL; on output the path, after the leading /
   *    user           NULL if no user/password permitted
   *    password       holder for password
   *    host           holder for host
   *    port           port number; only set if one is supplied.
   *
   * Returns an error string.
   */
  PROXY_DECLARE(char *)
       ap_proxy_canon_netloc(apr_pool_t *p, char **const urlp, char **userp,
              char **passwordp, char **hostp, apr_port_t *port)
  {
      char *addr, *scope_id, *strp, *host, *url = *urlp;
      char *user = NULL, *password = NULL;
      apr_port_t tmp_port;
      apr_status_t rv;
  
      if (url[0] != '/' || url[1] != '/') {
          return "Malformed URL";
      }
      host = url + 2;
      url = strchr(host, '/');
      if (url == NULL) {
          url = "";
      }
      else {
          *(url++) = '\0';    /* skip separating '/' */
      }
  
      /* find _last_ '@' since it might occur in user/password part */
      strp = strrchr(host, '@');
  
      if (strp != NULL) {
          *strp = '\0';
          user = host;
          host = strp + 1;
  
  /* find password */
          strp = strchr(user, ':');
          if (strp != NULL) {
              *strp = '\0';
              password = ap_proxy_canonenc(p, strp + 1, strlen(strp + 1), enc_user, 1, 0);
              if (password == NULL) {
                  return "Bad %-escape in URL (password)";
              }
          }
  
          user = ap_proxy_canonenc(p, user, strlen(user), enc_user, 1, 0);
          if (user == NULL) {
              return "Bad %-escape in URL (username)";
          }
      }
      if (userp != NULL) {
          *userp = user;
      }
      if (passwordp != NULL) {
          *passwordp = password;
      }
  
      /*
       * Parse the host string to separate host portion from optional port.
       * Perform range checking on port.
       */
      rv = apr_parse_addr_port(&addr, &scope_id, &tmp_port, host, p);
      if (rv != APR_SUCCESS || addr == NULL || scope_id != NULL) {
          return "Invalid host/port";
      }
      if (tmp_port != 0) { /* only update caller's port if port was specified */
          *port = tmp_port;
      }
  
      ap_str_tolower(addr); /* DNS names are case-insensitive */
  
      *urlp = url;
      *hostp = addr;
  
      return NULL;
  }
  
  PROXY_DECLARE(int) ap_proxyerror(request_rec *r, int statuscode, const char *message)
  {
      apr_table_setn(r->notes, "error-notes",
          apr_pstrcat(r->pool,
              "The proxy server could not handle the request<p>"
              "Reason: <strong>", ap_escape_html(r->pool, message),
              "</strong></p>",
              NULL));
  
      /* Allow "error-notes" string to be printed by ap_send_error_response() */
      apr_table_setn(r->notes, "verbose-error-to", "*");
  
      r->status_line = apr_psprintf(r->pool, "%3.3u Proxy Error", statuscode);
      ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00898) "%s returned by %s", message,
                    r->uri);
      return statuscode;
  }
  
  static const char *
       proxy_get_host_of_request(request_rec *r)
  {
      char *url, *user = NULL, *password = NULL, *err, *host = NULL;
      apr_port_t port;
  
      if (r->hostname != NULL) {
          return r->hostname;
      }
  
      /* Set url to the first char after "scheme://" */
      if ((url = strchr(r->uri, ':')) == NULL || url[1] != '/' || url[2] != '/') {
          return NULL;
      }
  
      url = apr_pstrdup(r->pool, &url[1]);    /* make it point to "//", which is what proxy_canon_netloc expects */
  
      err = ap_proxy_canon_netloc(r->pool, &url, &user, &password, &host, &port);
  
      if (err != NULL) {
          ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00899) "%s", err);
      }
  
      r->hostname = host;
  
      return host;        /* ought to return the port, too */
  }
  
  /* Return TRUE if addr represents an IP address (or an IP network address) */
  PROXY_DECLARE(int) ap_proxy_is_ipaddr(struct dirconn_entry *This, apr_pool_t *p)
  {
      const char *addr = This->name;
      long ip_addr[4];
      int i, quads;
      long bits;
  
      /*
       * if the address is given with an explicit netmask, use that
       * Due to a deficiency in apr_inet_addr(), it is impossible to parse
       * "partial" addresses (with less than 4 quads) correctly, i.e.
       * 192.168.123 is parsed as 192.168.0.123, which is not what I want.
       * I therefore have to parse the IP address manually:
       * if (proxy_readmask(This->name, &This->addr.s_addr, &This->mask.s_addr) == 0)
       * addr and mask were set by proxy_readmask()
       * return 1;
       */
  
      /*
       * Parse IP addr manually, optionally allowing
       * abbreviated net addresses like 192.168.
       */
  
      /* Iterate over up to 4 (dotted) quads. */
      for (quads = 0; quads < 4 && *addr != '\0'; ++quads) {
          char *tmp;
  
          if (*addr == '/' && quads > 0) {  /* netmask starts here. */
              break;
          }
  
          if (!apr_isdigit(*addr)) {
              return 0;       /* no digit at start of quad */
          }
  
          ip_addr[quads] = strtol(addr, &tmp, 0);
  
          if (tmp == addr) {  /* expected a digit, found something else */
              return 0;
          }
  
          if (ip_addr[quads] < 0 || ip_addr[quads] > 255) {
              /* invalid octet */
              return 0;
          }
  
          addr = tmp;
  
          if (*addr == '.' && quads != 3) {
              ++addr;     /* after the 4th quad, a dot would be illegal */
          }
      }
  
      for (This->addr.s_addr = 0, i = 0; i < quads; ++i) {
          This->addr.s_addr |= htonl(ip_addr[i] << (24 - 8 * i));
      }
  
      if (addr[0] == '/' && apr_isdigit(addr[1])) {   /* net mask follows: */
          char *tmp;
  
          ++addr;
  
          bits = strtol(addr, &tmp, 0);
  
          if (tmp == addr) {   /* expected a digit, found something else */
              return 0;
          }
  
          addr = tmp;
  
          if (bits < 0 || bits > 32) { /* netmask must be between 0 and 32 */
              return 0;
          }
  
      }
      else {
          /*
           * Determine (i.e., "guess") netmask by counting the
           * number of trailing .0's; reduce #quads appropriately
           * (so that 192.168.0.0 is equivalent to 192.168.)
           */
          while (quads > 0 && ip_addr[quads - 1] == 0) {
              --quads;
          }
  
          /* "IP Address should be given in dotted-quad form, optionally followed by a netmask (e.g., 192.168.111.0/24)"; */
          if (quads < 1) {
              return 0;
          }
  
          /* every zero-byte counts as 8 zero-bits */
          bits = 8 * quads;
  
          if (bits != 32) {     /* no warning for fully qualified IP address */
              ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00900)
                           "Warning: NetMask not supplied with IP-Addr; guessing: %s/%ld",
                           inet_ntoa(This->addr), bits);
          }
      }
  
      This->mask.s_addr = htonl(APR_INADDR_NONE << (32 - bits));
  
      if (*addr == '\0' && (This->addr.s_addr & ~This->mask.s_addr) != 0) {
          ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00901)
                       "Warning: NetMask and IP-Addr disagree in %s/%ld",
                       inet_ntoa(This->addr), bits);
          This->addr.s_addr &= This->mask.s_addr;
          ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00902)
                       "         Set to %s/%ld", inet_ntoa(This->addr), bits);
      }
  
      if (*addr == '\0') {
          This->matcher = proxy_match_ipaddr;
          return 1;
      }
      else {
          return (*addr == '\0'); /* okay iff we've parsed the whole string */
      }
  }
  
  /* Return TRUE if addr represents an IP address (or an IP network address) */
  static int proxy_match_ipaddr(struct dirconn_entry *This, request_rec *r)
  {
      int i, ip_addr[4];
      struct in_addr addr, *ip;
      const char *host = proxy_get_host_of_request(r);
  
      if (host == NULL) {   /* oops! */
         return 0;
      }
  
      memset(&addr, '\0', sizeof addr);
      memset(ip_addr, '\0', sizeof ip_addr);
  
      if (4 == sscanf(host, "%d.%d.%d.%d", &ip_addr[0], &ip_addr[1], &ip_addr[2], &ip_addr[3])) {
          for (addr.s_addr = 0, i = 0; i < 4; ++i) {
              /* ap_proxy_is_ipaddr() already confirmed that we have
               * a valid octet in ip_addr[i]
               */
              addr.s_addr |= htonl(ip_addr[i] << (24 - 8 * i));
          }
  
          if (This->addr.s_addr == (addr.s_addr & This->mask.s_addr)) {
  #if DEBUGGING
              ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00903)
                           "1)IP-Match: %s[%s] <-> ", host, inet_ntoa(addr));
              ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00904)
                           "%s/", inet_ntoa(This->addr));
              ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00905)
                           "%s", inet_ntoa(This->mask));
  #endif
              return 1;
          }
  #if DEBUGGING
          else {
              ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00906)
                           "1)IP-NoMatch: %s[%s] <-> ", host, inet_ntoa(addr));
              ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00907)
                           "%s/", inet_ntoa(This->addr));
              ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00908)
                           "%s", inet_ntoa(This->mask));
          }
  #endif
      }
      else {
          struct apr_sockaddr_t *reqaddr;
  
          if (apr_sockaddr_info_get(&reqaddr, host, APR_UNSPEC, 0, 0, r->pool)
              != APR_SUCCESS) {
  #if DEBUGGING
              ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00909)
               "2)IP-NoMatch: hostname=%s msg=Host not found", host);
  #endif
              return 0;
          }
  
          /* Try to deal with multiple IP addr's for a host */
          /* FIXME: This needs to be able to deal with IPv6 */
          while (reqaddr) {
              ip = (struct in_addr *) reqaddr->ipaddr_ptr;
              if (This->addr.s_addr == (ip->s_addr & This->mask.s_addr)) {
  #if DEBUGGING
                  ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00910)
                               "3)IP-Match: %s[%s] <-> ", host, inet_ntoa(*ip));
                  ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00911)
                               "%s/", inet_ntoa(This->addr));
                  ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00912)
                               "%s", inet_ntoa(This->mask));
  #endif
                  return 1;
              }
  #if DEBUGGING
              else {
                  ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00913)
                               "3)IP-NoMatch: %s[%s] <-> ", host, inet_ntoa(*ip));
                  ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00914)
                               "%s/", inet_ntoa(This->addr));
                  ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00915)
                               "%s", inet_ntoa(This->mask));
              }
  #endif
              reqaddr = reqaddr->next;
          }
      }
  
      return 0;
  }
  
  /* Return TRUE if addr represents a domain name */
  PROXY_DECLARE(int) ap_proxy_is_domainname(struct dirconn_entry *This, apr_pool_t *p)
  {
      char *addr = This->name;
      int i;
  
      /* Domain name must start with a '.' */
      if (addr[0] != '.') {
          return 0;
      }
  
      /* rfc1035 says DNS names must consist of "[-a-zA-Z0-9]" and '.' */
      for (i = 0; apr_isalnum(addr[i]) || addr[i] == '-' || addr[i] == '.'; ++i) {
          continue;
      }
  
  #if 0
      if (addr[i] == ':') {
      ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(03234)
                       "@@@@ handle optional port in proxy_is_domainname()");
      /* @@@@ handle optional port */
      }
  #endif
  
      if (addr[i] != '\0') {
          return 0;
      }
  
      /* Strip trailing dots */
      for (i = strlen(addr) - 1; i > 0 && addr[i] == '.'; --i) {
          addr[i] = '\0';
      }
  
      This->matcher = proxy_match_domainname;
      return 1;
  }
  
  /* Return TRUE if host "host" is in domain "domain" */
  static int proxy_match_domainname(struct dirconn_entry *This, request_rec *r)
  {
      const char *host = proxy_get_host_of_request(r);
      int d_len = strlen(This->name), h_len;
  
      if (host == NULL) {      /* some error was logged already */
          return 0;
      }
  
      h_len = strlen(host);
  
      /* @@@ do this within the setup? */
      /* Ignore trailing dots in domain comparison: */
      while (d_len > 0 && This->name[d_len - 1] == '.') {
          --d_len;
      }
      while (h_len > 0 && host[h_len - 1] == '.') {
          --h_len;
      }
      return h_len > d_len
          && strncasecmp(&host[h_len - d_len], This->name, d_len) == 0;
  }
  
  /* Return TRUE if host represents a host name */
  PROXY_DECLARE(int) ap_proxy_is_hostname(struct dirconn_entry *This, apr_pool_t *p)
  {
      struct apr_sockaddr_t *addr;
      char *host = This->name;
      int i;
  
      /* Host names must not start with a '.' */
      if (host[0] == '.') {
          return 0;
      }
      /* rfc1035 says DNS names must consist of "[-a-zA-Z0-9]" and '.' */
      for (i = 0; apr_isalnum(host[i]) || host[i] == '-' || host[i] == '.'; ++i);
  
      if (host[i] != '\0' || apr_sockaddr_info_get(&addr, host, APR_UNSPEC, 0, 0, p) != APR_SUCCESS) {
          return 0;
      }
  
      This->hostaddr = addr;
  
      /* Strip trailing dots */
      for (i = strlen(host) - 1; i > 0 && host[i] == '.'; --i) {
          host[i] = '\0';
      }
  
      This->matcher = proxy_match_hostname;
      return 1;
  }
  
  /* Return TRUE if host "host" is equal to host2 "host2" */
  static int proxy_match_hostname(struct dirconn_entry *This, request_rec *r)
  {
      char *host = This->name;
      const char *host2 = proxy_get_host_of_request(r);
      int h2_len;
      int h1_len;
  
      if (host == NULL || host2 == NULL) {
          return 0; /* oops! */
      }
  
      h2_len = strlen(host2);
      h1_len = strlen(host);
  
  #if 0
      struct apr_sockaddr_t *addr = *This->hostaddr;
  
      /* Try to deal with multiple IP addr's for a host */
      while (addr) {
          if (addr->ipaddr_ptr == ? ? ? ? ? ? ? ? ? ? ? ? ?)
              return 1;
          addr = addr->next;
      }
  #endif
  
      /* Ignore trailing dots in host2 comparison: */
      while (h2_len > 0 && host2[h2_len - 1] == '.') {
          --h2_len;
      }
      while (h1_len > 0 && host[h1_len - 1] == '.') {
          --h1_len;
      }
      return h1_len == h2_len
          && strncasecmp(host, host2, h1_len) == 0;
  }
  
  /* Return TRUE if addr is to be matched as a word */
  PROXY_DECLARE(int) ap_proxy_is_word(struct dirconn_entry *This, apr_pool_t *p)
  {
      This->matcher = proxy_match_word;
      return 1;
  }
  
  /* Return TRUE if string "str2" occurs literally in "str1" */
  static int proxy_match_word(struct dirconn_entry *This, request_rec *r)
  {
      const char *host = proxy_get_host_of_request(r);
      return host != NULL && ap_strstr_c(host, This->name) != NULL;
  }
  
  #define MAX_IP_STR_LEN (46)
  
  PROXY_DECLARE(int) ap_proxy_checkproxyblock(request_rec *r, proxy_server_conf *conf,
                                              const char *hostname, apr_sockaddr_t *addr)
  {
      int j;
  
      /* XXX FIXME: conf->noproxies->elts is part of an opaque structure */
      for (j = 0; j < conf->noproxies->nelts; j++) {
          struct noproxy_entry *npent = (struct noproxy_entry *) conf->noproxies->elts;
          struct apr_sockaddr_t *conf_addr;
  
          ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                        "checking remote machine [%s] against [%s]",
                        hostname, npent[j].name);
          if (ap_strstr_c(hostname, npent[j].name) || npent[j].name[0] == '*') {
              ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(00916)
                            "connect to remote machine %s blocked: name %s "
                            "matched", hostname, npent[j].name);
              return HTTP_FORBIDDEN;
          }
  
          /* No IP address checks if no IP address was passed in,
           * i.e. the forward address proxy case, where this server does
           * not resolve the hostname.  */
          if (!addr)
              continue;
  
          for (conf_addr = npent[j].addr; conf_addr; conf_addr = conf_addr->next) {
              char caddr[MAX_IP_STR_LEN], uaddr[MAX_IP_STR_LEN];
              apr_sockaddr_t *uri_addr;
  
              if (apr_sockaddr_ip_getbuf(caddr, sizeof caddr, conf_addr))
                  continue;
  
              for (uri_addr = addr; uri_addr; uri_addr = uri_addr->next) {
                  if (apr_sockaddr_ip_getbuf(uaddr, sizeof uaddr, uri_addr))
                      continue;
                  ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                                "ProxyBlock comparing %s and %s", caddr, uaddr);
                  if (!strcmp(caddr, uaddr)) {
                      ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(00917)
                                    "connect to remote machine %s blocked: "
                                    "IP %s matched", hostname, caddr);
                      return HTTP_FORBIDDEN;
                  }
              }
          }
      }
  
      return OK;
  }
  
  /* set up the minimal filter set */
  PROXY_DECLARE(int) ap_proxy_pre_http_request(conn_rec *c, request_rec *r)
  {
      ap_add_input_filter("HTTP_IN", NULL, r, c);
      return OK;
  }
  
  PROXY_DECLARE(const char *) ap_proxy_location_reverse_map(request_rec *r,
                                proxy_dir_conf *conf, const char *url)
  {
      proxy_req_conf *rconf;
      struct proxy_alias *ent;
      int i, l1, l1_orig, l2;
      char *u;
  
      /*
       * XXX FIXME: Make sure this handled the ambiguous case of the :<PORT>
       * after the hostname
       * XXX FIXME: Ensure the /uri component is a case sensitive match
       */
      if (r->proxyreq != PROXYREQ_REVERSE) {
          return url;
      }
  
      l1_orig = strlen(url);
      if (conf->interpolate_env == 1) {
          rconf = ap_get_module_config(r->request_config, &proxy_module);
          ent = (struct proxy_alias *)rconf->raliases->elts;
      }
      else {
          ent = (struct proxy_alias *)conf->raliases->elts;
      }
      for (i = 0; i < conf->raliases->nelts; i++) {
          proxy_server_conf *sconf = (proxy_server_conf *)
              ap_get_module_config(r->server->module_config, &proxy_module);
          proxy_balancer *balancer;
          const char *real = ent[i].real;
  
          /* Restore the url length, if it had been changed by the code below */
          l1 = l1_orig;
  
          /*
           * First check if mapping against a balancer and see
           * if we have such a entity. If so, then we need to
           * find the particulars of the actual worker which may
           * or may not be the right one... basically, we need
           * to find which member actually handled this request.
           */
          if (ap_proxy_valid_balancer_name((char *)real, 0) &&
              (balancer = ap_proxy_get_balancer(r->pool, sconf, real, 1))) {
              int n, l3 = 0;
              proxy_worker **worker = (proxy_worker **)balancer->workers->elts;
              const char *urlpart = ap_strchr_c(real + sizeof(BALANCER_PREFIX) - 1, '/');
              if (urlpart) {
                  if (!urlpart[1])
                      urlpart = NULL;
                  else
                      l3 = strlen(urlpart);
              }
              /* The balancer comparison is a bit trickier.  Given the context
               *   BalancerMember balancer://alias http://example.com/foo
               *   ProxyPassReverse /bash balancer://alias/bar
               * translate url http://example.com/foo/bar/that to /bash/that
               */
              for (n = 0; n < balancer->workers->nelts; n++) {
                  l2 = strlen((*worker)->s->name);
                  if (urlpart) {
                      /* urlpart (l3) assuredly starts with its own '/' */
                      if ((*worker)->s->name[l2 - 1] == '/')
                          --l2;
                      if (l1 >= l2 + l3
                              && strncasecmp((*worker)->s->name, url, l2) == 0
                              && strncmp(urlpart, url + l2, l3) == 0) {
                          u = apr_pstrcat(r->pool, ent[i].fake, &url[l2 + l3],
                                          NULL);
                          return ap_is_url(u) ? u : ap_construct_url(r->pool, u, r);
                      }
                  }
                  else if (l1 >= l2 && strncasecmp((*worker)->s->name, url, l2) == 0) {
                      /* edge case where fake is just "/"... avoid double slash */
                      if ((ent[i].fake[0] == '/') && (ent[i].fake[1] == 0) && (url[l2] == '/')) {
                          u = apr_pstrdup(r->pool, &url[l2]);
                      } else {
                          u = apr_pstrcat(r->pool, ent[i].fake, &url[l2], NULL);
                      }
                      return ap_is_url(u) ? u : ap_construct_url(r->pool, u, r);
                  }
                  worker++;
              }
          }
          else {
              const char *part = url;
              l2 = strlen(real);
              if (real[0] == '/') {
                  part = ap_strstr_c(url, "://");
                  if (part) {
                      part = ap_strchr_c(part+3, '/');
                      if (part) {
                          l1 = strlen(part);
                      }
                      else {
                          part = url;
                      }
                  }
                  else {
                      part = url;
                  }
              }
              if (l2 > 0 && l1 >= l2 && strncasecmp(real, part, l2) == 0) {
                  u = apr_pstrcat(r->pool, ent[i].fake, &part[l2], NULL);
                  return ap_is_url(u) ? u : ap_construct_url(r->pool, u, r);
              }
          }
      }
  
      return url;
  }
  
  /*
   * Cookies are a bit trickier to match: we've got two substrings to worry
   * about, and we can't just find them with strstr 'cos of case.  Regexp
   * matching would be an easy fix, but for better consistency with all the
   * other matches we'll refrain and use apr_strmatch to find path=/domain=
   * and stick to plain strings for the config values.
   */
  PROXY_DECLARE(const char *) ap_proxy_cookie_reverse_map(request_rec *r,
                                proxy_dir_conf *conf, const char *str)
  {
      proxy_req_conf *rconf = ap_get_module_config(r->request_config,
                                                   &proxy_module);
      struct proxy_alias *ent;
      apr_size_t len = strlen(str);
      const char *newpath = NULL;
      const char *newdomain = NULL;
      const char *pathp;
      const char *domainp;
      const char *pathe = NULL;
      const char *domaine = NULL;
      apr_size_t l1, l2, poffs = 0, doffs = 0;
      int i;
      int ddiff = 0;
      int pdiff = 0;
      char *tmpstr, *tmpstr_orig, *token, *last, *ret;
  
      if (r->proxyreq != PROXYREQ_REVERSE) {
          return str;
      }
  
     /*
      * Find the match and replacement, but save replacing until we've done
      * both path and domain so we know the new strlen
      */
      tmpstr_orig = tmpstr = apr_pstrdup(r->pool, str);
      while ((token = apr_strtok(tmpstr, ";", &last))) {
          /* skip leading spaces */
          while (apr_isspace(*token)) {
              ++token;
          }
  
          if (ap_cstr_casecmpn("path=", token, 5) == 0) {
              pathp = token + 5;
              poffs = pathp - tmpstr_orig;
              l1 = strlen(pathp);
              pathe = str + poffs + l1;
              if (conf->interpolate_env == 1) {
                  ent = (struct proxy_alias *)rconf->cookie_paths->elts;
              }
              else {
                  ent = (struct proxy_alias *)conf->cookie_paths->elts;
              }
              for (i = 0; i < conf->cookie_paths->nelts; i++) {
                  l2 = strlen(ent[i].fake);
                  if (l1 >= l2 && strncmp(ent[i].fake, pathp, l2) == 0) {
                      newpath = ent[i].real;
                      pdiff = strlen(newpath) - l1;
                      break;
                  }
              }
          }
          else if (ap_cstr_casecmpn("domain=", token, 7) == 0) {
              domainp = token + 7;
              doffs = domainp - tmpstr_orig;
              l1 = strlen(domainp);
              domaine = str + doffs + l1;
              if (conf->interpolate_env == 1) {
                  ent = (struct proxy_alias *)rconf->cookie_domains->elts;
              }
              else {
                  ent = (struct proxy_alias *)conf->cookie_domains->elts;
              }
              for (i = 0; i < conf->cookie_domains->nelts; i++) {
                  l2 = strlen(ent[i].fake);
                  if (l1 >= l2 && strncasecmp(ent[i].fake, domainp, l2) == 0) {
                      newdomain = ent[i].real;
                      ddiff = strlen(newdomain) - l1;
                      break;
                  }
              }
          }
  
          /* Iterate the remaining tokens using apr_strtok(NULL, ...) */
          tmpstr = NULL;
      }
  
      if (newpath) {
          ret = apr_palloc(r->pool, len + pdiff + ddiff + 1);
          l1 = strlen(newpath);
          if (newdomain) {
              l2 = strlen(newdomain);
              if (doffs > poffs) {
                  memcpy(ret, str, poffs);
                  memcpy(ret + poffs, newpath, l1);
                  memcpy(ret + poffs + l1, pathe, str + doffs - pathe);
                  memcpy(ret + doffs + pdiff, newdomain, l2);
                  strcpy(ret + doffs + pdiff + l2, domaine);
              }
              else {
                  memcpy(ret, str, doffs) ;
                  memcpy(ret + doffs, newdomain, l2);
                  memcpy(ret + doffs + l2, domaine, str + poffs - domaine);
                  memcpy(ret + poffs + ddiff, newpath, l1);
                  strcpy(ret + poffs + ddiff + l1, pathe);
              }
          }
          else {
              memcpy(ret, str, poffs);
              memcpy(ret + poffs, newpath, l1);
              strcpy(ret + poffs + l1, pathe);
          }
      }
      else if (newdomain) {
              ret = apr_palloc(r->pool, len + ddiff + 1);
              l2 = strlen(newdomain);
              memcpy(ret, str, doffs);
              memcpy(ret + doffs, newdomain, l2);
              strcpy(ret + doffs + l2, domaine);
      }
      else {
          ret = (char *)str; /* no change */
      }
  
      return ret;
  }
  
  /*
   * BALANCER related...
   */
  
  /*
   * verifies that the balancer name conforms to standards.
   */
  PROXY_DECLARE(int) ap_proxy_valid_balancer_name(char *name, int i)
  {
      if (!i)
          i = sizeof(BALANCER_PREFIX)-1;
      return (!ap_cstr_casecmpn(name, BALANCER_PREFIX, i));
  }
  
  
  PROXY_DECLARE(proxy_balancer *) ap_proxy_get_balancer(apr_pool_t *p,
                                                        proxy_server_conf *conf,
                                                        const char *url,
                                                        int care)
  {
      proxy_balancer *balancer;
      char *c, *uri = apr_pstrdup(p, url);
      int i;
      proxy_hashes hash;
  
      c = strchr(uri, ':');
      if (c == NULL || c[1] != '/' || c[2] != '/' || c[3] == '\0') {
          return NULL;
      }
      /* remove path from uri */
      if ((c = strchr(c + 3, '/'))) {
          *c = '\0';
      }
      ap_str_tolower(uri);
      hash.def = ap_proxy_hashfunc(uri, PROXY_HASHFUNC_DEFAULT);
      hash.fnv = ap_proxy_hashfunc(uri, PROXY_HASHFUNC_FNV);
      balancer = (proxy_balancer *)conf->balancers->elts;
      for (i = 0; i < conf->balancers->nelts; i++) {
          if (balancer->hash.def == hash.def && balancer->hash.fnv == hash.fnv) {
              if (!care || !balancer->s->inactive) {
                  return balancer;
              }
          }
          balancer++;
      }
      return NULL;
  }
  
  
  PROXY_DECLARE(char *) ap_proxy_update_balancer(apr_pool_t *p,
                                                  proxy_balancer *balancer,
                                                  const char *url)
  {
      apr_uri_t puri;
      if (!url) {
          return NULL;
      }
      if (apr_uri_parse(p, url, &puri) != APR_SUCCESS) {
          return apr_psprintf(p, "unable to parse: %s", url);
      }
      if (puri.path && PROXY_STRNCPY(balancer->s->vpath, puri.path) != APR_SUCCESS) {
          return apr_psprintf(p, "balancer %s front-end virtual-path (%s) too long",
                              balancer->s->name, puri.path);
      }
      if (puri.hostname && PROXY_STRNCPY(balancer->s->vhost, puri.hostname) != APR_SUCCESS) {
          return apr_psprintf(p, "balancer %s front-end vhost name (%s) too long",
                              balancer->s->name, puri.hostname);
      }
      return NULL;
  }
  
  #define PROXY_UNSET_NONCE '\n'
  
  PROXY_DECLARE(char *) ap_proxy_define_balancer(apr_pool_t *p,
                                                 proxy_balancer **balancer,
                                                 proxy_server_conf *conf,
                                                 const char *url,
                                                 const char *alias,
                                                 int do_malloc)
  {
      proxy_balancer_method *lbmethod;
      proxy_balancer_shared *bshared;
      char *c, *q, *uri = apr_pstrdup(p, url);
      const char *sname;
  
      /* We should never get here without a valid BALANCER_PREFIX... */
  
      c = strchr(uri, ':');
      if (c == NULL || c[1] != '/' || c[2] != '/' || c[3] == '\0')
          return apr_psprintf(p, "Bad syntax for a balancer name (%s)", uri);
      /* remove path from uri */
      if ((q = strchr(c + 3, '/')))
          *q = '\0';
  
      ap_str_tolower(uri);
      *balancer = apr_array_push(conf->balancers);
      memset(*balancer, 0, sizeof(proxy_balancer));
  
      /*
       * NOTE: The default method is byrequests - if it doesn't
       * exist, that's OK at this time. We check when we share and sync
       */
      lbmethod = ap_lookup_provider(PROXY_LBMETHOD, "byrequests", "0");
      (*balancer)->lbmethod = lbmethod;
      
      (*balancer)->workers = apr_array_make(p, 5, sizeof(proxy_worker *));
  #if APR_HAS_THREADS
      (*balancer)->gmutex = NULL;
      (*balancer)->tmutex = NULL;
  #endif
  
      if (do_malloc)
          bshared = ap_malloc(sizeof(proxy_balancer_shared));
      else
          bshared = apr_palloc(p, sizeof(proxy_balancer_shared));
  
      memset(bshared, 0, sizeof(proxy_balancer_shared));
  
      bshared->was_malloced = (do_malloc != 0);
      PROXY_STRNCPY(bshared->lbpname, "byrequests");
      if (PROXY_STRNCPY(bshared->name, uri) != APR_SUCCESS) {
          return apr_psprintf(p, "balancer name (%s) too long", uri);
      }
      (*balancer)->lbmethod_set = 1;
  
      /*
       * We do the below for verification. The real sname will be
       * done post_config
       */
      ap_pstr2_alnum(p, bshared->name + sizeof(BALANCER_PREFIX) - 1,
                     &sname);
      sname = apr_pstrcat(p, conf->id, "_", sname, NULL);
      if (PROXY_STRNCPY(bshared->sname, sname) != APR_SUCCESS) {
          return apr_psprintf(p, "balancer safe-name (%s) too long", sname);
      }
      bshared->hash.def = ap_proxy_hashfunc(bshared->name, PROXY_HASHFUNC_DEFAULT);
      bshared->hash.fnv = ap_proxy_hashfunc(bshared->name, PROXY_HASHFUNC_FNV);
      (*balancer)->hash = bshared->hash;
  
      bshared->forcerecovery = 1;
      bshared->sticky_separator = '.';
      *bshared->nonce = PROXY_UNSET_NONCE;  /* impossible valid input */
  
      (*balancer)->s = bshared;
      (*balancer)->sconf = conf;
  
      return ap_proxy_update_balancer(p, *balancer, alias);
  }
  
  /*
   * Create an already defined balancer and free up memory.
   */
  PROXY_DECLARE(apr_status_t) ap_proxy_share_balancer(proxy_balancer *balancer,
                                                      proxy_balancer_shared *shm,
                                                      int i)
  {
      apr_status_t rv = APR_SUCCESS;
      proxy_balancer_method *lbmethod;
      char *action = "copying";
      if (!shm || !balancer->s)
          return APR_EINVAL;
  
      if ((balancer->s->hash.def != shm->hash.def) ||
          (balancer->s->hash.fnv != shm->hash.fnv)) {
          memcpy(shm, balancer->s, sizeof(proxy_balancer_shared));
          if (balancer->s->was_malloced)
              free(balancer->s);
      } else {
          action = "re-using";
      }
      balancer->s = shm;
      balancer->s->index = i;
      ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02337)
                   "%s shm[%d] (0x%pp) for %s", action, i, (void *)shm,
                   balancer->s->name);
      /* the below should always succeed */
      lbmethod = ap_lookup_provider(PROXY_LBMETHOD, balancer->s->lbpname, "0");
      if (lbmethod) {
          balancer->lbmethod = lbmethod;
          balancer->lbmethod_set = 1;
      } else {
          ap_log_error(APLOG_MARK, APLOG_CRIT, 0, ap_server_conf, APLOGNO(02432)
                       "Cannot find LB Method: %s", balancer->s->lbpname);
          return APR_EINVAL;
      }
      if (*balancer->s->nonce == PROXY_UNSET_NONCE) {
          char nonce[APR_UUID_FORMATTED_LENGTH + 1];
          apr_uuid_t uuid;
  
          /* Generate a pseudo-UUID from the PRNG to use as a nonce for
           * the lifetime of the process. uuid.data is a char array so
           * this is an adequate substitute for apr_uuid_get(). */
          ap_random_insecure_bytes(uuid.data, sizeof uuid.data);
          apr_uuid_format(nonce, &uuid);
          rv = PROXY_STRNCPY(balancer->s->nonce, nonce);
      }
      return rv;
  }
  
  PROXY_DECLARE(apr_status_t) ap_proxy_initialize_balancer(proxy_balancer *balancer, server_rec *s, apr_pool_t *p)
  {
  #if APR_HAS_THREADS
      apr_status_t rv = APR_SUCCESS;
  #endif
      ap_slotmem_provider_t *storage = balancer->storage;
      apr_size_t size;
      unsigned int num;
  
      if (!storage) {
          ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(00918)
                       "no provider for %s", balancer->s->name);
          return APR_EGENERAL;
      }
      /*
       * for each balancer we need to init the global
       * mutex and then attach to the shared worker shm
       */
      if (!balancer->gmutex) {
          ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(00919)
                       "no mutex %s", balancer->s->name);
          return APR_EGENERAL;
      }
  
      /* Re-open the mutex for the child. */
      rv = apr_global_mutex_child_init(&(balancer->gmutex),
                                       apr_global_mutex_lockfile(balancer->gmutex),
                                       p);
      if (rv != APR_SUCCESS) {
          ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s, APLOGNO(00920)
                       "Failed to reopen mutex %s in child",
                       balancer->s->name);
          return rv;
      }
  
      /* now attach */
      storage->attach(&(balancer->wslot), balancer->s->sname, &size, &num, p);
      if (!balancer->wslot) {
          ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(00921) "slotmem_attach failed");
          return APR_EGENERAL;
      }
      if (balancer->lbmethod && balancer->lbmethod->reset)
          balancer->lbmethod->reset(balancer, s);
  
  #if APR_HAS_THREADS
      if (balancer->tmutex == NULL) {
          rv = apr_thread_mutex_create(&(balancer->tmutex), APR_THREAD_MUTEX_DEFAULT, p);
          if (rv != APR_SUCCESS) {
              ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(00922)
                           "can not create balancer thread mutex");
              return rv;
          }
      }
  #endif
      return APR_SUCCESS;
  }
  
  static proxy_worker *proxy_balancer_get_best_worker(proxy_balancer *balancer,
                                                      request_rec *r,
                                                      proxy_is_best_callback_fn_t *is_best,
                                                      void *baton)
  {
      int i = 0;
      int cur_lbset = 0;
      int max_lbset = 0;
      int unusable_workers = 0;
      apr_pool_t *tpool = NULL;
      apr_array_header_t *spares = NULL;
      apr_array_header_t *standbys = NULL;
      proxy_worker *worker = NULL;
      proxy_worker *best_worker = NULL;
  
      ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(10122)
                   "proxy: Entering %s for BALANCER (%s)",
                   balancer->lbmethod->name, balancer->s->name);
  
      apr_pool_create(&tpool, r->pool);
      apr_pool_tag(tpool, "proxy_lb_best");
  
      spares = apr_array_make(tpool, 1, sizeof(proxy_worker*));
      standbys = apr_array_make(tpool, 1, sizeof(proxy_worker*));
  
      /* Process lbsets in order, only replacing unusable workers in a given lbset
       * with available spares from the same lbset. Hot standbys will be used as a
       * last resort when all other workers and spares are unavailable.
       */
      for (cur_lbset = 0; !best_worker && (cur_lbset <= max_lbset); cur_lbset++) {
          unusable_workers = 0;
          apr_array_clear(spares);
          apr_array_clear(standbys);
  
          for (i = 0; i < balancer->workers->nelts; i++) {
              worker = APR_ARRAY_IDX(balancer->workers, i, proxy_worker *);
  
              if (worker->s->lbset > max_lbset) {
                  max_lbset = worker->s->lbset;
              }
  
              if (worker->s->lbset != cur_lbset) {
                  continue;
              }
  
              /* A draining worker that is neither a spare nor a standby should be
               * considered unusable to be replaced by spares.
               */
              if (PROXY_WORKER_IS_DRAINING(worker)) {
                  if (!PROXY_WORKER_IS_SPARE(worker) && !PROXY_WORKER_IS_STANDBY(worker)) {
                      unusable_workers++;
                  }
  
                  continue;
              }
  
              /* If the worker is in error state run retry on that worker. It will
               * be marked as operational if the retry timeout is elapsed.  The
               * worker might still be unusable, but we try anyway.
               */
              if (!PROXY_WORKER_IS_USABLE(worker)) {
                  ap_proxy_retry_worker("BALANCER", worker, r->server);
              }
  
              if (PROXY_WORKER_IS_SPARE(worker)) {
                  if (PROXY_WORKER_IS_USABLE(worker)) {
                      APR_ARRAY_PUSH(spares, proxy_worker *) = worker;
                  }
              }
              else if (PROXY_WORKER_IS_STANDBY(worker)) {
                  if (PROXY_WORKER_IS_USABLE(worker)) {
                      APR_ARRAY_PUSH(standbys, proxy_worker *) = worker;
                  }
              }
              else if (PROXY_WORKER_IS_USABLE(worker)) {
                if (is_best(worker, best_worker, baton)) {
                  best_worker = worker;
                }
              }
              else {
                  unusable_workers++;
              }
          }
  
          /* Check if any spares are best. */
          for (i = 0; (i < spares->nelts) && (i < unusable_workers); i++) {
            worker = APR_ARRAY_IDX(spares, i, proxy_worker *);
  
            if (is_best(worker, best_worker, baton)) {
              best_worker = worker;
            }
          }
  
          /* If no workers are available, use the standbys. */
          if (!best_worker) {
              for (i = 0; i < standbys->nelts; i++) {
                worker = APR_ARRAY_IDX(standbys, i, proxy_worker *);
  
                if (is_best(worker, best_worker, baton)) {
                  best_worker = worker;
                }
              }
          }
      }
  
      apr_pool_destroy(tpool);
  
      if (best_worker) {
          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(10123)
                       "proxy: %s selected worker \"%s\" : busy %" APR_SIZE_T_FMT " : lbstatus %d",
                       balancer->lbmethod->name, best_worker->s->name, best_worker->s->busy, best_worker->s->lbstatus);
      }
  
      return best_worker;
  }
  
  PROXY_DECLARE(proxy_worker *) ap_proxy_balancer_get_best_worker(proxy_balancer *balancer,
                                                                  request_rec *r,
                                                                  proxy_is_best_callback_fn_t *is_best,
                                                                  void *baton)
  {
      return proxy_balancer_get_best_worker(balancer, r, is_best, baton);
  }
  
  /*
   * CONNECTION related...
   */
  
  static void socket_cleanup(proxy_conn_rec *conn)
  {
      conn->sock = NULL;
      conn->tmp_bb = NULL;
      conn->connection = NULL;
      conn->ssl_hostname = NULL;
      apr_pool_clear(conn->scpool);
  }
  
  static apr_status_t conn_pool_cleanup(void *theworker)
  {
      ((proxy_worker *)theworker)->cp = NULL;
      return APR_SUCCESS;
  }
  
  static void init_conn_pool(apr_pool_t *p, proxy_worker *worker)
  {
      apr_pool_t *pool;
      apr_pool_t *dns_pool;
      proxy_conn_pool *cp;
  
      /*
       * Create a connection pool's subpool.
       * This pool is used for connection recycling.
       * Once the worker is added it is never removed but
       * it can be disabled.
       */
      apr_pool_create(&pool, p);
      apr_pool_tag(pool, "proxy_worker_cp");
      /*
       * Create a subpool of the connection pool for worker
       * scoped DNS resolutions. This is needed to avoid race
       * conditions in using the connection pool by multiple
       * threads during ramp up.
       */
      apr_pool_create(&dns_pool, pool);
      apr_pool_tag(dns_pool, "proxy_worker_dns");
      /*
       * Alloc from the same pool as worker.
       * proxy_conn_pool is permanently attached to the worker.
       */
      cp = (proxy_conn_pool *)apr_pcalloc(p, sizeof(proxy_conn_pool));
      cp->pool = pool;
      cp->dns_pool = dns_pool;
      worker->cp = cp;
  }
  
  PROXY_DECLARE(int) ap_proxy_connection_reusable(proxy_conn_rec *conn)
  {
      proxy_worker *worker = conn->worker;
  
      return ! (conn->close || !worker->s->is_address_reusable || worker->s->disablereuse);
  }
  
  static apr_status_t connection_cleanup(void *theconn)
  {
      proxy_conn_rec *conn = (proxy_conn_rec *)theconn;
      proxy_worker *worker = conn->worker;
  
      if (conn->r) {
          apr_pool_destroy(conn->r->pool);
          conn->r = NULL;
      }
  
      /* Sanity check: Did we already return the pooled connection? */
      if (conn->inreslist) {
          ap_log_perror(APLOG_MARK, APLOG_ERR, 0, conn->pool, APLOGNO(00923)
                        "Pooled connection 0x%pp for worker %s has been"
                        " already returned to the connection pool.", conn,
                        ap_proxy_worker_name(conn->pool, worker));
          return APR_SUCCESS;
      }
  
      /* determine if the connection need to be closed */
      if (!worker->s->is_address_reusable || worker->s->disablereuse) {
          apr_pool_t *p = conn->pool;
          apr_pool_clear(p);
          conn = apr_pcalloc(p, sizeof(proxy_conn_rec));
          conn->pool = p;
          conn->worker = worker;
          apr_pool_create(&(conn->scpool), p);
          apr_pool_tag(conn->scpool, "proxy_conn_scpool");
      }
      else if (conn->close
                  || (conn->connection
                      && conn->connection->keepalive == AP_CONN_CLOSE)) {
          socket_cleanup(conn);
          conn->close = 0;
      }
      else if (conn->is_ssl) {
          /* Unbind/reset the SSL connection dir config (sslconn->dc) from
           * r->per_dir_config, r will likely get destroyed before this proxy
           * conn is reused.
           */
          ap_proxy_ssl_engine(conn->connection, worker->section_config, 1);
      }
  
      if (worker->s->hmax && worker->cp->res) {
          conn->inreslist = 1;
          apr_reslist_release(worker->cp->res, (void *)conn);
      }
      else
      {
          worker->cp->conn = conn;
      }
  
      /* Always return the SUCCESS */
      return APR_SUCCESS;
  }
  
  /* DEPRECATED */
  PROXY_DECLARE(apr_status_t) ap_proxy_ssl_connection_cleanup(proxy_conn_rec *conn,
                                                              request_rec *r)
  {
      apr_status_t rv;
  
      /*
       * If we have an existing SSL connection it might be possible that the
       * server sent some SSL message we have not read so far (e.g. an SSL
       * shutdown message if the server closed the keepalive connection while
       * the connection was held unused in our pool).
       * So ensure that if present (=> APR_NONBLOCK_READ) it is read and
       * processed. We don't expect any data to be in the returned brigade.
       */
      if (conn->sock && conn->connection) {
          rv = ap_get_brigade(conn->connection->input_filters, conn->tmp_bb,
                              AP_MODE_READBYTES, APR_NONBLOCK_READ,
                              HUGE_STRING_LEN);
          if (!APR_BRIGADE_EMPTY(conn->tmp_bb)) {
              apr_off_t len;
  
              rv = apr_brigade_length(conn->tmp_bb, 0, &len);
              ap_log_rerror(APLOG_MARK, APLOG_TRACE3, rv, r,
                            "SSL cleanup brigade contained %"
                            APR_OFF_T_FMT " bytes of data.", len);
              apr_brigade_cleanup(conn->tmp_bb);
          }
          if ((rv != APR_SUCCESS) && !APR_STATUS_IS_EAGAIN(rv)) {
              socket_cleanup(conn);
          }
      }
      return APR_SUCCESS;
  }
  
  /* reslist constructor */
  static apr_status_t connection_constructor(void **resource, void *params,
                                             apr_pool_t *pool)
  {
      apr_pool_t *ctx;
      apr_pool_t *scpool;
      proxy_conn_rec *conn;
      proxy_worker *worker = (proxy_worker *)params;
  
      /*
       * Create the subpool for each connection
       * This keeps the memory consumption constant
       * when disconnecting from backend.
       */
      apr_pool_create(&ctx, pool);
      apr_pool_tag(ctx, "proxy_conn_pool");
      /*
       * Create another subpool that manages the data for the
       * socket and the connection member of the proxy_conn_rec struct as we
       * destroy this data more frequently than other data in the proxy_conn_rec
       * struct like hostname and addr (at least in the case where we have
       * keepalive connections that timed out).
       */
      apr_pool_create(&scpool, ctx);
      apr_pool_tag(scpool, "proxy_conn_scpool");
      conn = apr_pcalloc(ctx, sizeof(proxy_conn_rec));
  
      conn->pool   = ctx;
      conn->scpool = scpool;
      conn->worker = worker;
      conn->inreslist = 1;
      *resource = conn;
  
      return APR_SUCCESS;
  }
  
  /* reslist destructor */
  static apr_status_t connection_destructor(void *resource, void *params,
                                            apr_pool_t *pool)
  {
      proxy_worker *worker = params;
  
      /* Destroy the pool only if not called from reslist_destroy */
      if (worker->cp) {
          proxy_conn_rec *conn = resource;
          apr_pool_destroy(conn->pool);
      }
  
      return APR_SUCCESS;
  }
  
  /*
   * WORKER related...
   */
  
  PROXY_DECLARE(char *) ap_proxy_worker_name(apr_pool_t *p,
                                             proxy_worker *worker)
  {
      if (!(*worker->s->uds_path) || !p) {
          /* just in case */
          return worker->s->name;
      }
      return apr_pstrcat(p, "unix:", worker->s->uds_path, "|", worker->s->name, NULL);
  }
  
  PROXY_DECLARE(int) ap_proxy_worker_can_upgrade(apr_pool_t *p,
                                                 const proxy_worker *worker,
                                                 const char *upgrade)
  {
      const char *worker_upgrade = worker->s->upgrade;
      return (*worker_upgrade
              && (strcmp(worker_upgrade, "*") == 0
                  || ap_cstr_casecmp(worker_upgrade, upgrade) == 0
                  || ap_find_token(p, worker_upgrade, upgrade)));
  }
  
  /*
   * Taken from ap_strcmp_match() :
   * Match = 0, NoMatch = 1, Abort = -1, Inval = -2
   * Based loosely on sections of wildmat.c by Rich Salz
   * Hmmm... shouldn't this really go component by component?
   *
   * Adds handling of the "\<any>" => "<any>" unescaping.
   */
  static int ap_proxy_strcmp_ematch(const char *str, const char *expected)
  {
      apr_size_t x, y;
  
      for (x = 0, y = 0; expected[y]; ++y, ++x) {
          if (expected[y] == '$' && apr_isdigit(expected[y + 1])) {
              do {
                  y += 2;
              } while (expected[y] == '$' && apr_isdigit(expected[y + 1]));
              if (!expected[y])
                  return 0;
              while (str[x]) {
                  int ret;
                  if ((ret = ap_proxy_strcmp_ematch(&str[x++], &expected[y])) != 1)
                      return ret;
              }
              return -1;
          }
          else if (!str[x]) {
              return -1;
          }
          else if (expected[y] == '\\' && !expected[++y]) {
              /* NUL is an invalid char! */
              return -2;
          }
          if (str[x] != expected[y])
              return 1;
      }
      /* We got all the way through the worker path without a difference */
      return 0;
  }
  
  PROXY_DECLARE(proxy_worker *) ap_proxy_get_worker(apr_pool_t *p,
                                                    proxy_balancer *balancer,
                                                    proxy_server_conf *conf,
                                                    const char *url)
  {
      proxy_worker *worker;
      proxy_worker *max_worker = NULL;
      int max_match = 0;
      int url_length;
      int min_match;
      int worker_name_length;
      const char *c;
      char *url_copy;
      int i;
  
      if (!url) {
          return NULL;
      }
  
      url = ap_proxy_de_socketfy(p, url);
  
      c = ap_strchr_c(url, ':');
      if (c == NULL || c[1] != '/' || c[2] != '/' || c[3] == '\0') {
          return NULL;
      }
  
      url_length = strlen(url);
      url_copy = apr_pstrmemdup(p, url, url_length);
  
      /*
       * We need to find the start of the path and
       * therefore we know the length of the scheme://hostname/
       * part to we can force-lowercase everything up to
       * the start of the path.
       */
      c = ap_strchr_c(c+3, '/');
      if (c) {
          char *pathstart;
          pathstart = url_copy + (c - url);
          *pathstart = '\0';
          ap_str_tolower(url_copy);
          min_match = strlen(url_copy);
          *pathstart = '/';
      }
      else {
          ap_str_tolower(url_copy);
          min_match = strlen(url_copy);
      }
      /*
       * Do a "longest match" on the worker name to find the worker that
       * fits best to the URL, but keep in mind that we must have at least
       * a minimum matching of length min_match such that
       * scheme://hostname[:port] matches between worker and url.
       */
  
      if (balancer) {
          proxy_worker **workers = (proxy_worker **)balancer->workers->elts;
          for (i = 0; i < balancer->workers->nelts; i++, workers++) {
              worker = *workers;
              if ( ((worker_name_length = strlen(worker->s->name)) <= url_length)
                  && (worker_name_length >= min_match)
                  && (worker_name_length > max_match)
                  && (worker->s->is_name_matchable
                      || strncmp(url_copy, worker->s->name,
                                 worker_name_length) == 0)
                  && (!worker->s->is_name_matchable
                      || ap_proxy_strcmp_ematch(url_copy,
                                                worker->s->name) == 0) ) {
                  max_worker = worker;
                  max_match = worker_name_length;
              }
          }
      } else {
          worker = (proxy_worker *)conf->workers->elts;
          for (i = 0; i < conf->workers->nelts; i++, worker++) {
              if ( ((worker_name_length = strlen(worker->s->name)) <= url_length)
                  && (worker_name_length >= min_match)
                  && (worker_name_length > max_match)
                  && (worker->s->is_name_matchable
                      || strncmp(url_copy, worker->s->name,
                                 worker_name_length) == 0)
                  && (!worker->s->is_name_matchable
                      || ap_proxy_strcmp_ematch(url_copy,
                                                worker->s->name) == 0) ) {
                  max_worker = worker;
                  max_match = worker_name_length;
              }
          }
      }
  
      return max_worker;
  }
  
  /*
   * To create a worker from scratch first we define the
   * specifics of the worker; this is all local data.
   * We then allocate space for it if data needs to be
   * shared. This allows for dynamic addition during
   * config and runtime.
   */
  PROXY_DECLARE(char *) ap_proxy_define_worker(apr_pool_t *p,
                                               proxy_worker **worker,
                                               proxy_balancer *balancer,
                                               proxy_server_conf *conf,
                                               const char *url,
                                               int do_malloc)
  {
      int rv;
      apr_uri_t uri, urisock;
      proxy_worker_shared *wshared;
      char *ptr, *sockpath = NULL;
  
      /*
       * Look to see if we are using UDS:
       * require format: unix:/path/foo/bar.sock|http://ignored/path2/
       * This results in talking http to the socket at /path/foo/bar.sock
       */
      ptr = ap_strchr((char *)url, '|');
      if (ptr) {
          *ptr = '\0';
          rv = apr_uri_parse(p, url, &urisock);
          if (rv == APR_SUCCESS && !ap_cstr_casecmp(urisock.scheme, "unix")) {
              sockpath = ap_runtime_dir_relative(p, urisock.path);;
              url = ptr+1;    /* so we get the scheme for the uds */
          }
          else {
              *ptr = '|';
          }
      }
      rv = apr_uri_parse(p, url, &uri);
  
      if (rv != APR_SUCCESS) {
          return apr_pstrcat(p, "Unable to parse URL: ", url, NULL);
      }
      if (!uri.scheme) {
          return apr_pstrcat(p, "URL must be absolute!: ", url, NULL);
      }
      /* allow for unix:/path|http: */
      if (!uri.hostname) {
          if (sockpath) {
              uri.hostname = "localhost";
          }
          else {
              return apr_pstrcat(p, "URL must be absolute!: ", url, NULL);
          }
      }
      else {
          ap_str_tolower(uri.hostname);
      }
      ap_str_tolower(uri.scheme);
      /*
       * Workers can be associated w/ balancers or on their
       * own; ie: the generic reverse-proxy or a worker
       * in a simple ProxyPass statement. eg:
       *
       *      ProxyPass / http://www.example.com
       *
       * in which case the worker goes in the conf slot.
       */
      if (balancer) {
          proxy_worker **runtime;
          /* recall that we get a ptr to the ptr here */
          runtime = apr_array_push(balancer->workers);
          *worker = *runtime = apr_palloc(p, sizeof(proxy_worker));   /* right to left baby */
          /* we've updated the list of workers associated with
           * this balancer *locally* */
          balancer->wupdated = apr_time_now();
      } else if (conf) {
          *worker = apr_array_push(conf->workers);
      } else {
          /* we need to allocate space here */
          *worker = apr_palloc(p, sizeof(proxy_worker));
      }
  
      memset(*worker, 0, sizeof(proxy_worker));
      /* right here we just want to tuck away the worker info.
       * if called during config, we don't have shm setup yet,
       * so just note the info for later. */
      if (do_malloc)
          wshared = ap_malloc(sizeof(proxy_worker_shared));  /* will be freed ap_proxy_share_worker */
      else
          wshared = apr_palloc(p, sizeof(proxy_worker_shared));
  
      memset(wshared, 0, sizeof(proxy_worker_shared));
  
      wshared->port = (uri.port ? uri.port : ap_proxy_port_of_scheme(uri.scheme));
      if (uri.port && uri.port == ap_proxy_port_of_scheme(uri.scheme)) {
          uri.port = 0;
      }
      ptr = apr_uri_unparse(p, &uri, APR_URI_UNP_REVEALPASSWORD);
      if (PROXY_STRNCPY(wshared->name, ptr) != APR_SUCCESS) {
          ap_log_error(APLOG_MARK, APLOG_ERR, 0, ap_server_conf, APLOGNO(02808)
          "Alert! worker name (%s) too long; truncated to: %s", ptr, wshared->name);
      }
      if (PROXY_STRNCPY(wshared->scheme, uri.scheme) != APR_SUCCESS) {
          ap_log_error(APLOG_MARK, APLOG_ERR, 0, ap_server_conf, APLOGNO(010117)
          "Alert! worker scheme (%s) too long; truncated to: %s", uri.scheme, wshared->scheme);
      }
      if (PROXY_STRNCPY(wshared->hostname_ex, uri.hostname) != APR_SUCCESS) {
          return apr_psprintf(p, "worker hostname (%s) too long", uri.hostname);
      }
      if (PROXY_STRNCPY(wshared->hostname, uri.hostname) != APR_SUCCESS) {
          ap_log_error(APLOG_MARK, APLOG_INFO, 0, ap_server_conf, APLOGNO(010118)
          "worker hostname (%s) too long; truncated for legacy modules that do not use "
          "proxy_worker_shared->hostname_ex: %s", uri.hostname, wshared->hostname);
      }
      wshared->flush_packets = flush_off;
      wshared->flush_wait = PROXY_FLUSH_WAIT;
      wshared->is_address_reusable = 1;
      wshared->lbfactor = 100;
      wshared->passes = 1;
      wshared->fails = 1;
      wshared->interval = apr_time_from_sec(HCHECK_WATHCHDOG_DEFAULT_INTERVAL);
      wshared->smax = -1;
      wshared->hash.def = ap_proxy_hashfunc(wshared->name, PROXY_HASHFUNC_DEFAULT);
      wshared->hash.fnv = ap_proxy_hashfunc(wshared->name, PROXY_HASHFUNC_FNV);
      wshared->was_malloced = (do_malloc != 0);
      wshared->is_name_matchable = 0;
      if (sockpath) {
          if (PROXY_STRNCPY(wshared->uds_path, sockpath) != APR_SUCCESS) {
              return apr_psprintf(p, "worker uds path (%s) too long", sockpath);
          }
  
      }
      else {
          *wshared->uds_path = '\0';
      }
      if (!balancer) {
          wshared->status |= PROXY_WORKER_IGNORE_ERRORS;
      }
  
      (*worker)->hash = wshared->hash;
      (*worker)->context = NULL;
      (*worker)->cp = NULL;
      (*worker)->balancer = balancer;
      (*worker)->s = wshared;
  
      return NULL;
  }
  
  PROXY_DECLARE(char *) ap_proxy_define_match_worker(apr_pool_t *p,
                                               proxy_worker **worker,
                                               proxy_balancer *balancer,
                                               proxy_server_conf *conf,
                                               const char *url,
                                               int do_malloc)
  {
      char *err;
      const char *pdollar = ap_strchr_c(url, '$');
  
      if (pdollar != NULL) {
          url = apr_pstrmemdup(p, url, pdollar - url);
      }
      err = ap_proxy_define_worker(p, worker, balancer, conf, url, do_malloc);
      if (err) {
          return err;
      }
  
      (*worker)->s->is_name_matchable = 1;
      if (pdollar) {
          /* Before ap_proxy_define_match_worker() existed, a regex worker
           * with dollar substitution was never matched against the actual
           * URL thus the request fell through the generic worker. To avoid
           * dns and connection reuse compat issues, let's disable connection
           * reuse by default, it can still be overwritten by an explicit
           * enablereuse=on.
           */
          (*worker)->s->disablereuse = 1;
      }
      return NULL;
  }
  
  /*
   * Create an already defined worker and free up memory
   */
  PROXY_DECLARE(apr_status_t) ap_proxy_share_worker(proxy_worker *worker, proxy_worker_shared *shm,
                                                    int i)
  {
      char *action = "copying";
      if (!shm || !worker->s)
          return APR_EINVAL;
  
      if ((worker->s->hash.def != shm->hash.def) ||
          (worker->s->hash.fnv != shm->hash.fnv)) {
          memcpy(shm, worker->s, sizeof(proxy_worker_shared));
          if (worker->s->was_malloced)
              free(worker->s); /* was malloced in ap_proxy_define_worker */
      } else {
          action = "re-using";
      }
      worker->s = shm;
      worker->s->index = i;
  
      if (APLOGdebug(ap_server_conf)) {
          apr_pool_t *pool;
          apr_pool_create(&pool, ap_server_conf->process->pool);
          apr_pool_tag(pool, "proxy_worker_name");
          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02338)
                       "%s shm[%d] (0x%pp) for worker: %s", action, i, (void *)shm,
                       ap_proxy_worker_name(pool, worker));
          if (pool) {
              apr_pool_destroy(pool);
          }
      }
      return APR_SUCCESS;
  }
  
  PROXY_DECLARE(apr_status_t) ap_proxy_initialize_worker(proxy_worker *worker, server_rec *s, apr_pool_t *p)
  {
      APR_OPTIONAL_FN_TYPE(http2_get_num_workers) *get_h2_num_workers;
      apr_status_t rv = APR_SUCCESS;
      int max_threads, minw, maxw;
  
      if (worker->s->status & PROXY_WORKER_INITIALIZED) {
          /* The worker is already initialized */
          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00924)
                       "worker %s shared already initialized",
                       ap_proxy_worker_name(p, worker));
      }
      else {
          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00925)
                       "initializing worker %s shared",
                       ap_proxy_worker_name(p, worker));
          /* Set default parameters */
          if (!worker->s->retry_set) {
              worker->s->retry = apr_time_from_sec(PROXY_WORKER_DEFAULT_RETRY);
          }
          /* By default address is reusable unless DisableReuse is set */
          if (worker->s->disablereuse) {
              worker->s->is_address_reusable = 0;
          }
          else {
              worker->s->is_address_reusable = 1;
          }
  
          /*
           * When mod_http2 is loaded we might have more threads since it has
           * its own pool of processing threads.
           */
          ap_mpm_query(AP_MPMQ_MAX_THREADS, &max_threads);
          get_h2_num_workers = APR_RETRIEVE_OPTIONAL_FN(http2_get_num_workers);
          if (get_h2_num_workers) {
              get_h2_num_workers(s, &minw, &maxw);
              /* So now the max is:
               *   max_threads-1 threads for HTTP/1 each requiring one connection
               *   + one thread for HTTP/2 requiring maxw connections
               */
              max_threads = max_threads - 1 + maxw;
          }
          if (max_threads > 1) {
              /* Default hmax is max_threads to scale with the load and never
               * wait for an idle connection to proceed.
               */
              if (worker->s->hmax == 0) {
                  worker->s->hmax = max_threads;
              }
              if (worker->s->smax == -1 || worker->s->smax > worker->s->hmax) {
                  worker->s->smax = worker->s->hmax;
              }
              /* Set min to be lower than smax */
              if (worker->s->min > worker->s->smax) {
                  worker->s->min = worker->s->smax;
              }
          }
          else {
              /* This will suppress the apr_reslist creation */
              worker->s->min = worker->s->smax = worker->s->hmax = 0;
          }
      }
  
      /* What if local is init'ed and shm isn't?? Even possible? */
      if (worker->local_status & PROXY_WORKER_INITIALIZED) {
          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00926)
                       "worker %s local already initialized",
                       ap_proxy_worker_name(p, worker));
      }
      else {
          apr_global_mutex_lock(proxy_mutex);
          /* Check again after we got the lock if we are still uninitialized */
          if (!(AP_VOLATILIZE_T(unsigned int, worker->local_status) & PROXY_WORKER_INITIALIZED)) {
              ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00927)
                           "initializing worker %s local",
                           ap_proxy_worker_name(p, worker));
              /* Now init local worker data */
  #if APR_HAS_THREADS
              if (worker->tmutex == NULL) {
                  rv = apr_thread_mutex_create(&(worker->tmutex), APR_THREAD_MUTEX_DEFAULT, p);
                  if (rv != APR_SUCCESS) {
                      ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00928)
                                   "can not create worker thread mutex");
                      apr_global_mutex_unlock(proxy_mutex);
                      return rv;
                  }
              }
  #endif
              if (worker->cp == NULL)
                  init_conn_pool(p, worker);
              if (worker->cp == NULL) {
                  ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(00929)
                               "can not create connection pool");
                  apr_global_mutex_unlock(proxy_mutex);
                  return APR_EGENERAL;
              }
  
              if (worker->s->hmax) {
                  rv = apr_reslist_create(&(worker->cp->res),
                                          worker->s->min, worker->s->smax,
                                          worker->s->hmax, worker->s->ttl,
                                          connection_constructor, connection_destructor,
                                          worker, worker->cp->pool);
  
                  apr_pool_pre_cleanup_register(worker->cp->pool, worker,
                                                conn_pool_cleanup);
  
                  ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00930)
                      "initialized pool in child %" APR_PID_T_FMT " for (%s) min=%d max=%d smax=%d",
                       getpid(), worker->s->hostname_ex, worker->s->min,
                       worker->s->hmax, worker->s->smax);
  
                  /* Set the acquire timeout */
                  if (rv == APR_SUCCESS && worker->s->acquire_set) {
                      apr_reslist_timeout_set(worker->cp->res, worker->s->acquire);
                  }
  
              }
              else {
                  void *conn;
  
                  rv = connection_constructor(&conn, worker, worker->cp->pool);
                  worker->cp->conn = conn;
  
                  ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, s, APLOGNO(00931)
                       "initialized single connection worker in child %" APR_PID_T_FMT " for (%s)",
                       getpid(), worker->s->hostname_ex);
              }
              if (rv == APR_SUCCESS) {
                  worker->local_status |= (PROXY_WORKER_INITIALIZED);
              }
          }
          apr_global_mutex_unlock(proxy_mutex);
  
      }
      if (rv == APR_SUCCESS) {
          worker->s->status |= (PROXY_WORKER_INITIALIZED);
      }
      return rv;
  }
  
  static int ap_proxy_retry_worker(const char *proxy_function, proxy_worker *worker,
          server_rec *s)
  {
      if (worker->s->status & PROXY_WORKER_IN_ERROR) {
          if (PROXY_WORKER_IS(worker, PROXY_WORKER_STOPPED)) {
              ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(3305)
                           "%s: Won't retry worker (%s): stopped",
                           proxy_function, worker->s->hostname_ex);
              return DECLINED;
          }
          if ((worker->s->status & PROXY_WORKER_IGNORE_ERRORS)
              || apr_time_now() > worker->s->error_time + worker->s->retry) {
              ++worker->s->retries;
              worker->s->status &= ~PROXY_WORKER_IN_ERROR;
              ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00932)
                           "%s: worker for (%s) has been marked for retry",
                           proxy_function, worker->s->hostname_ex);
              return OK;
          }
          else {
              ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00933)
                           "%s: too soon to retry worker for (%s)",
                           proxy_function, worker->s->hostname_ex);
              return DECLINED;
          }
      }
      else {
          return OK;
      }
  }
  
  /*
   * In the case of the reverse proxy, we need to see if we
   * were passed a UDS url (eg: from mod_proxy) and adjust uds_path
   * as required.  
   */
  static void fix_uds_filename(request_rec *r, char **url) 
  {
      char *ptr, *ptr2;
      if (!r || !r->filename) return;
  
      if (!strncmp(r->filename, "proxy:", 6) &&
              (ptr2 = ap_strcasestr(r->filename, "unix:")) &&
              (ptr = ap_strchr(ptr2, '|'))) {
          apr_uri_t urisock;
          apr_status_t rv;
          *ptr = '\0';
          rv = apr_uri_parse(r->pool, ptr2, &urisock);
          if (rv == APR_SUCCESS) {
              char *rurl = ptr+1;
              char *sockpath = ap_runtime_dir_relative(r->pool, urisock.path);
              apr_table_setn(r->notes, "uds_path", sockpath);
              *url = apr_pstrdup(r->pool, rurl); /* so we get the scheme for the uds */
              /* r->filename starts w/ "proxy:", so add after that */
              memmove(r->filename+6, rurl, strlen(rurl)+1);
              ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                      "*: rewrite of url due to UDS(%s): %s (%s)",
                      sockpath, *url, r->filename);
          }
          else {
              *ptr = '|';
          }
      }
  }
  
  PROXY_DECLARE(int) ap_proxy_pre_request(proxy_worker **worker,
                                          proxy_balancer **balancer,
                                          request_rec *r,
                                          proxy_server_conf *conf, char **url)
  {
      int access_status;
  
      access_status = proxy_run_pre_request(worker, balancer, r, conf, url);
      if (access_status == DECLINED && *balancer == NULL) {
          *worker = ap_proxy_get_worker(r->pool, NULL, conf, *url);
          if (*worker) {
              ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                            "%s: found worker %s for %s",
                            (*worker)->s->scheme, (*worker)->s->name, *url);
              *balancer = NULL;
              fix_uds_filename(r, url);
              access_status = OK;
          }
          else if (r->proxyreq == PROXYREQ_PROXY) {
              if (conf->forward) {
                  ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                                "*: found forward proxy worker for %s", *url);
                  *balancer = NULL;
                  *worker = conf->forward;
                  access_status = OK;
                  /*
                   * The forward worker does not keep connections alive, so
                   * ensure that mod_proxy_http does the correct thing
                   * regarding the Connection header in the request.
                   */
                  apr_table_setn(r->subprocess_env, "proxy-nokeepalive", "1");
              }
          }
          else if (r->proxyreq == PROXYREQ_REVERSE) {
              if (conf->reverse) {
                  ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                                "*: using default reverse proxy worker for %s (no keepalive)", *url);
                  *balancer = NULL;
                  *worker = conf->reverse;
                  access_status = OK;
                  /*
                   * The reverse worker does not keep connections alive, so
                   * ensure that mod_proxy_http does the correct thing
                   * regarding the Connection header in the request.
                   */
                  apr_table_setn(r->subprocess_env, "proxy-nokeepalive", "1");
                  fix_uds_filename(r, url);
              }
          }
      }
      else if (access_status == DECLINED && *balancer != NULL) {
          /* All the workers are busy */
          ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00934)
                        "all workers are busy.  Unable to serve %s", *url);
          access_status = HTTP_SERVICE_UNAVAILABLE;
      }
      return access_status;
  }
  
  PROXY_DECLARE(int) ap_proxy_post_request(proxy_worker *worker,
                                           proxy_balancer *balancer,
                                           request_rec *r,
                                           proxy_server_conf *conf)
  {
      int access_status = OK;
      if (balancer) {
          access_status = proxy_run_post_request(worker, balancer, r, conf);
          if (access_status == DECLINED) {
              access_status = OK; /* no post_request handler available */
              /* TODO: recycle direct worker */
          }
      }
  
      return access_status;
  }
  
  /* DEPRECATED */
  PROXY_DECLARE(int) ap_proxy_connect_to_backend(apr_socket_t **newsock,
                                                 const char *proxy_function,
                                                 apr_sockaddr_t *backend_addr,
                                                 const char *backend_name,
                                                 proxy_server_conf *conf,
                                                 request_rec *r)
  {
      apr_status_t rv;
      int connected = 0;
      int loglevel;
  
      while (backend_addr && !connected) {
          if ((rv = apr_socket_create(newsock, backend_addr->family,
                                      SOCK_STREAM, 0, r->pool)) != APR_SUCCESS) {
              loglevel = backend_addr->next ? APLOG_DEBUG : APLOG_ERR;
              ap_log_rerror(APLOG_MARK, loglevel, rv, r, APLOGNO(00935)
                            "%s: error creating fam %d socket for target %s",
                            proxy_function, backend_addr->family, backend_name);
              /*
               * this could be an IPv6 address from the DNS but the
               * local machine won't give us an IPv6 socket; hopefully the
               * DNS returned an additional address to try
               */
              backend_addr = backend_addr->next;
              continue;
          }
  
          if (conf->recv_buffer_size > 0 &&
              (rv = apr_socket_opt_set(*newsock, APR_SO_RCVBUF,
                                       conf->recv_buffer_size))) {
              ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(00936)
                            "apr_socket_opt_set(SO_RCVBUF): Failed to set "
                            "ProxyReceiveBufferSize, using default");
          }
  
          rv = apr_socket_opt_set(*newsock, APR_TCP_NODELAY, 1);
          if (rv != APR_SUCCESS && rv != APR_ENOTIMPL) {
              ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(00937)
                            "apr_socket_opt_set(APR_TCP_NODELAY): "
                            "Failed to set");
          }
  
          /* Set a timeout on the socket */
          if (conf->timeout_set) {
              apr_socket_timeout_set(*newsock, conf->timeout);
          }
          else {
              apr_socket_timeout_set(*newsock, r->server->timeout);
          }
  
          ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                        "%s: fam %d socket created to connect to %s",
                        proxy_function, backend_addr->family, backend_name);
  
          if (conf->source_address) {
              apr_sockaddr_t *local_addr;
              /* Make a copy since apr_socket_bind() could change
               * conf->source_address, which we don't want.
               */
              local_addr = apr_pmemdup(r->pool, conf->source_address,
                                       sizeof(apr_sockaddr_t));
              local_addr->pool = r->pool;
              rv = apr_socket_bind(*newsock, local_addr);
              if (rv != APR_SUCCESS) {
                  ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(00938)
                                "%s: failed to bind socket to local address",
                                proxy_function);
              }
          }
  
          /* make the connection out of the socket */
          rv = apr_socket_connect(*newsock, backend_addr);
  
          /* if an error occurred, loop round and try again */
          if (rv != APR_SUCCESS) {
              apr_socket_close(*newsock);
              loglevel = backend_addr->next ? APLOG_DEBUG : APLOG_ERR;
              ap_log_rerror(APLOG_MARK, loglevel, rv, r, APLOGNO(00939)
                            "%s: attempt to connect to %pI (%s) failed",
                            proxy_function, backend_addr, backend_name);
              backend_addr = backend_addr->next;
              continue;
          }
          connected = 1;
      }
      return connected ? 0 : 1;
  }
  
  PROXY_DECLARE(int) ap_proxy_acquire_connection(const char *proxy_function,
                                                 proxy_conn_rec **conn,
                                                 proxy_worker *worker,
                                                 server_rec *s)
  {
      apr_status_t rv;
  
      if (!PROXY_WORKER_IS_USABLE(worker)) {
          /* Retry the worker */
          ap_proxy_retry_worker(proxy_function, worker, s);
  
          if (!PROXY_WORKER_IS_USABLE(worker)) {
              ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(00940)
                           "%s: disabled connection for (%s)",
                           proxy_function, worker->s->hostname_ex);
              return HTTP_SERVICE_UNAVAILABLE;
          }
      }
  
      if (worker->s->hmax && worker->cp->res) {
          rv = apr_reslist_acquire(worker->cp->res, (void **)conn);
      }
      else {
          /* create the new connection if the previous was destroyed */
          if (!worker->cp->conn) {
              rv = connection_constructor((void **)conn, worker, worker->cp->pool);
          }
          else {
              *conn = worker->cp->conn;
              worker->cp->conn = NULL;
              rv = APR_SUCCESS;
          }
      }
  
      if (rv != APR_SUCCESS) {
          ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00941)
                       "%s: failed to acquire connection for (%s)",
                       proxy_function, worker->s->hostname_ex);
          return HTTP_SERVICE_UNAVAILABLE;
      }
      ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00942)
                   "%s: has acquired connection for (%s)",
                   proxy_function, worker->s->hostname_ex);
  
      (*conn)->worker = worker;
      (*conn)->close  = 0;
      (*conn)->inreslist = 0;
  
      return OK;
  }
  
  PROXY_DECLARE(int) ap_proxy_release_connection(const char *proxy_function,
                                                 proxy_conn_rec *conn,
                                                 server_rec *s)
  {
      ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00943)
                  "%s: has released connection for (%s)",
                  proxy_function, conn->worker->s->hostname_ex);
      connection_cleanup(conn);
  
      return OK;
  }
  
  PROXY_DECLARE(int)
  ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
                                proxy_server_conf *conf,
                                proxy_worker *worker,
                                proxy_conn_rec *conn,
                                apr_uri_t *uri,
                                char **url,
                                const char *proxyname,
                                apr_port_t proxyport,
                                char *server_portstr,
                                int server_portstr_size)
  {
      int server_port;
      apr_status_t err = APR_SUCCESS;
  #if APR_HAS_THREADS
      apr_status_t uerr = APR_SUCCESS;
  #endif
      const char *uds_path;
  
      /*
       * Break up the URL to determine the host to connect to
       */
  
      /* we break the URL into host, port, uri */
      if (APR_SUCCESS != apr_uri_parse(p, *url, uri)) {
          return ap_proxyerror(r, HTTP_BAD_REQUEST,
                               apr_pstrcat(p,"URI cannot be parsed: ", *url,
                                           NULL));
      }
      if (!uri->port) {
          uri->port = ap_proxy_port_of_scheme(uri->scheme);
      }
  
      ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00944)
                   "connecting %s to %s:%d", *url, uri->hostname, uri->port);
  
      /*
       * allocate these out of the specified connection pool
       * The scheme handler decides if this is permanent or
       * short living pool.
       */
      /* Unless we are connecting the backend via a (forward Proxy)Remote, we
       * have to use the original form of the URI (non absolute), but this is
       * also the case via a remote proxy using the CONNECT method since the
       * original request (and URI) is to be embedded in the body.
       */
      if (!proxyname || conn->is_ssl) {
          *url = apr_pstrcat(p, uri->path, uri->query ? "?" : "",
                             uri->query ? uri->query : "",
                             uri->fragment ? "#" : "",
                             uri->fragment ? uri->fragment : "", NULL);
      }
      /*
       * Figure out if our passed in proxy_conn_rec has a usable
       * address cached.
       *
       * TODO: Handle this much better... 
       *
       * XXX: If generic workers are ever address-reusable, we need 
       *      to check host and port on the conn and be careful about
       *      spilling the cached addr from the worker.
       */
      uds_path = (*worker->s->uds_path ? worker->s->uds_path : apr_table_get(r->notes, "uds_path"));
      if (uds_path) {
          if (conn->uds_path == NULL) {
              /* use (*conn)->pool instead of worker->cp->pool to match lifetime */
              conn->uds_path = apr_pstrdup(conn->pool, uds_path);
          }
          if (conn->uds_path) {
              ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02545)
                           "%s: has determined UDS as %s",
                           uri->scheme, conn->uds_path);
          }
          else {
              /* should never happen */
              ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02546)
                           "%s: cannot determine UDS (%s)",
                           uri->scheme, uds_path);
  
          }
          /*
           * In UDS cases, some structs are NULL. Protect from de-refs
           * and provide info for logging at the same time.
           */
          if (!conn->addr) {
              apr_sockaddr_t *sa;
              apr_sockaddr_info_get(&sa, NULL, APR_UNSPEC, 0, 0, conn->pool);
              conn->addr = sa;
          }
          conn->hostname = "httpd-UDS";
          conn->port = 0;
      }
      else {
          int will_reuse = worker->s->is_address_reusable && !worker->s->disablereuse;
          if (!conn->hostname || !will_reuse) {
              if (proxyname) {
                  conn->hostname = apr_pstrdup(conn->pool, proxyname);
                  conn->port = proxyport;
                  /*
                   * If we have a forward proxy and the protocol is HTTPS,
                   * then we need to prepend a HTTP CONNECT request before
                   * sending our actual HTTPS requests.
                   * Save our real backend data for using it later during HTTP CONNECT.
                   */
                  if (conn->is_ssl) {
                      const char *proxy_auth;
  
                      forward_info *forward = apr_pcalloc(conn->pool, sizeof(forward_info));
                      conn->forward = forward;
                      forward->use_http_connect = 1;
                      forward->target_host = apr_pstrdup(conn->pool, uri->hostname);
                      forward->target_port = uri->port;
                      /* Do we want to pass Proxy-Authorization along?
                       * If we haven't used it, then YES
                       * If we have used it then MAYBE: RFC2616 says we MAY propagate it.
                       * So let's make it configurable by env.
                       * The logic here is the same used in mod_proxy_http.
                       */
                      proxy_auth = apr_table_get(r->headers_in, "Proxy-Authorization");
                      if (proxy_auth != NULL &&
                          proxy_auth[0] != '\0' &&
                          (r->user == NULL || /* we haven't yet authenticated */
                          apr_table_get(r->subprocess_env, "Proxy-Chain-Auth"))) {
                          forward->proxy_auth = apr_pstrdup(conn->pool, proxy_auth);
                      }
                  }
              }
              else {
                  conn->hostname = apr_pstrdup(conn->pool, uri->hostname);
                  conn->port = uri->port;
              }
              if (!will_reuse) {
                  /*
                   * Only do a lookup if we should not reuse the backend address.
                   * Otherwise we will look it up once for the worker.
                   */
                  err = apr_sockaddr_info_get(&(conn->addr),
                                              conn->hostname, APR_UNSPEC,
                                              conn->port, 0,
                                              conn->pool);
              }
              socket_cleanup(conn);
              conn->close = 0;
          }
          if (will_reuse) {
              /*
               * Looking up the backend address for the worker only makes sense if
               * we can reuse the address.
               */
              if (!worker->cp->addr) {
                  if ((err = PROXY_THREAD_LOCK(worker)) != APR_SUCCESS) {
                      ap_log_rerror(APLOG_MARK, APLOG_ERR, err, r, APLOGNO(00945) "lock");
                      return HTTP_INTERNAL_SERVER_ERROR;
                  }
  
                  /*
                   * Recheck addr after we got the lock. This may have changed
                   * while waiting for the lock.
                   */
                  if (!AP_VOLATILIZE_T(apr_sockaddr_t *, worker->cp->addr)) {
  
                      apr_sockaddr_t *addr;
  
                      /*
                       * Worker can have the single constant backend address.
                       * The single DNS lookup is used once per worker.
                       * If dynamic change is needed then set the addr to NULL
                       * inside dynamic config to force the lookup.
                       */
                      err = apr_sockaddr_info_get(&addr,
                                                  conn->hostname, APR_UNSPEC,
                                                  conn->port, 0,
                                                  worker->cp->dns_pool);
                      worker->cp->addr = addr;
                  }
                  conn->addr = worker->cp->addr;
                  if ((uerr = PROXY_THREAD_UNLOCK(worker)) != APR_SUCCESS) {
                      ap_log_rerror(APLOG_MARK, APLOG_ERR, uerr, r, APLOGNO(00946) "unlock");
                  }
              }
              else {
                  conn->addr = worker->cp->addr;
              }
          }
      }
      /* Close a possible existing socket if we are told to do so */
      if (conn->close) {
          socket_cleanup(conn);
          conn->close = 0;
      }
  
      if (err != APR_SUCCESS) {
          return ap_proxyerror(r, HTTP_GATEWAY_TIME_OUT,
                               apr_pstrcat(p, "DNS lookup failure for: ",
                                           conn->hostname, NULL));
      }
  
      /* Get the server port for the Via headers */
      server_port = ap_get_server_port(r);
      AP_DEBUG_ASSERT(server_portstr_size > 0);
      if (ap_is_default_port(server_port, r)) {
          server_portstr[0] = '\0';
      }
      else {
          apr_snprintf(server_portstr, server_portstr_size, ":%d",
                       server_port);
      }
  
      /* check if ProxyBlock directive on this host */
      if (OK != ap_proxy_checkproxyblock(r, conf, uri->hostname, 
                                         proxyname ? NULL : conn->addr)) {
          return ap_proxyerror(r, HTTP_FORBIDDEN,
                               "Connect to remote machine blocked");
      }
      /*
       * When SSL is configured, determine the hostname (SNI) for the request
       * and save it in conn->ssl_hostname. Close any reused connection whose
       * SNI differs.
       */
      if (conn->is_ssl) {
          proxy_dir_conf *dconf;
          const char *ssl_hostname;
          /*
           * In the case of ProxyPreserveHost on use the hostname of
           * the request if present otherwise use the one from the
           * backend request URI.
           */
          dconf = ap_get_module_config(r->per_dir_config, &proxy_module);
          if (dconf->preserve_host) {
              ssl_hostname = r->hostname;
          }
          else if (conn->forward
                   && ((forward_info *)(conn->forward))->use_http_connect) {
              ssl_hostname = ((forward_info *)conn->forward)->target_host;
          }
          else {
              ssl_hostname = conn->hostname;
          }
          /*
           * Close if a SNI is in use but this request requires no or
           * a different one, or no SNI is in use but one is required.
           */
          if ((conn->ssl_hostname && (!ssl_hostname ||
                                      strcasecmp(conn->ssl_hostname,
                                                 ssl_hostname) != 0)) ||
                  (!conn->ssl_hostname && ssl_hostname && conn->sock)) {
              socket_cleanup(conn);
          }
          if (conn->ssl_hostname == NULL) {
              conn->ssl_hostname = apr_pstrdup(conn->scpool, ssl_hostname);
          }
      }
      ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00947)
                   "connected %s to %s:%d", *url, conn->hostname, conn->port);
      return OK;
  }
  
  #define USE_ALTERNATE_IS_CONNECTED 1
  
  #if !defined(APR_MSG_PEEK) && defined(MSG_PEEK)
  #define APR_MSG_PEEK MSG_PEEK
  #endif
  
  #if USE_ALTERNATE_IS_CONNECTED && defined(APR_MSG_PEEK)
  PROXY_DECLARE(int) ap_proxy_is_socket_connected(apr_socket_t *socket)
  {
      apr_pollfd_t pfds[1];
      apr_status_t status;
      apr_int32_t  nfds;
  
      pfds[0].reqevents = APR_POLLIN;
      pfds[0].desc_type = APR_POLL_SOCKET;
      pfds[0].desc.s = socket;
  
      do {
          status = apr_poll(&pfds[0], 1, &nfds, 0);
      } while (APR_STATUS_IS_EINTR(status));
  
      if (status == APR_SUCCESS && nfds == 1 &&
          pfds[0].rtnevents == APR_POLLIN) {
          apr_sockaddr_t unused;
          apr_size_t len = 1;
          char buf[1];
          /* The socket might be closed in which case
           * the poll will return POLLIN.
           * If there is no data available the socket
           * is closed.
           */
          status = apr_socket_recvfrom(&unused, socket, APR_MSG_PEEK,
                                       &buf[0], &len);
          if (status == APR_SUCCESS && len)
              return 1;
          else
              return 0;
      }
      else if (APR_STATUS_IS_EAGAIN(status) || APR_STATUS_IS_TIMEUP(status)) {
          return 1;
      }
      return 0;
  
  }
  #else
  PROXY_DECLARE(int) ap_proxy_is_socket_connected(apr_socket_t *socket)
  
  {
      apr_size_t buffer_len = 1;
      char test_buffer[1];
      apr_status_t socket_status;
      apr_interval_time_t current_timeout;
  
      /* save timeout */
      apr_socket_timeout_get(sock, &current_timeout);
      /* set no timeout */
      apr_socket_timeout_set(sock, 0);
      socket_status = apr_socket_recv(sock, test_buffer, &buffer_len);
      /* put back old timeout */
      apr_socket_timeout_set(sock, current_timeout);
      if (APR_STATUS_IS_EOF(socket_status)
          || APR_STATUS_IS_ECONNRESET(socket_status)) {
          return 0;
      }
      else {
          return 1;
      }
  }
  #endif /* USE_ALTERNATE_IS_CONNECTED */
  
  
  /*
   * Send a HTTP CONNECT request to a forward proxy.
   * The proxy is given by "backend", the target server
   * is contained in the "forward" member of "backend".
   */
  static apr_status_t send_http_connect(proxy_conn_rec *backend,
                                        server_rec *s)
  {
      int status;
      apr_size_t nbytes;
      apr_size_t left;
      int complete = 0;
      char buffer[HUGE_STRING_LEN];
      char drain_buffer[HUGE_STRING_LEN];
      forward_info *forward = (forward_info *)backend->forward;
      int len = 0;
  
      ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00948)
                   "CONNECT: sending the CONNECT request for %s:%d "
                   "to the remote proxy %pI (%s)",
                   forward->target_host, forward->target_port,
                   backend->addr, backend->hostname);
      /* Create the CONNECT request */
      nbytes = apr_snprintf(buffer, sizeof(buffer),
                            "CONNECT %s:%d HTTP/1.0" CRLF,
                            forward->target_host, forward->target_port);
      /* Add proxy authorization from the initial request if necessary */
      if (forward->proxy_auth != NULL) {
          nbytes += apr_snprintf(buffer + nbytes, sizeof(buffer) - nbytes,
                                 "Proxy-Authorization: %s" CRLF,
                                 forward->proxy_auth);
      }
      /* Set a reasonable agent and send everything */
      nbytes += apr_snprintf(buffer + nbytes, sizeof(buffer) - nbytes,
                             "Proxy-agent: %s" CRLF CRLF,
                             ap_get_server_banner());
      ap_xlate_proto_to_ascii(buffer, nbytes);
      apr_socket_send(backend->sock, buffer, &nbytes);
  
      /* Receive the whole CONNECT response */
      left = sizeof(buffer) - 1;
      /* Read until we find the end of the headers or run out of buffer */
      do {
          nbytes = left;
          status = apr_socket_recv(backend->sock, buffer + len, &nbytes);
          len += nbytes;
          left -= nbytes;
          buffer[len] = '\0';
          if (strstr(buffer + len - nbytes, CRLF_ASCII CRLF_ASCII) != NULL) {
              ap_xlate_proto_from_ascii(buffer, len);
              complete = 1;
              break;
          }
      } while (status == APR_SUCCESS && left > 0);
      /* Drain what's left */
      if (!complete) {
          nbytes = sizeof(drain_buffer) - 1;
          while (status == APR_SUCCESS && nbytes) {
              status = apr_socket_recv(backend->sock, drain_buffer, &nbytes);
              drain_buffer[nbytes] = '\0';
              nbytes = sizeof(drain_buffer) - 1;
              if (strstr(drain_buffer, CRLF_ASCII CRLF_ASCII) != NULL) {
                  break;
              }
          }
      }
  
      /* Check for HTTP_OK response status */
      if (status == APR_SUCCESS) {
          unsigned int major, minor;
          /* Only scan for three character status code */
          char code_str[4];
  
          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00949)
                       "send_http_connect: response from the forward proxy: %s",
                       buffer);
  
          /* Extract the returned code */
          if (sscanf(buffer, "HTTP/%u.%u %3s", &major, &minor, code_str) == 3) {
              status = atoi(code_str);
              if (status == HTTP_OK) {
                  status = APR_SUCCESS;
              }
              else {
                  ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(00950)
                               "send_http_connect: the forward proxy returned code is '%s'",
                               code_str);
                  status = APR_INCOMPLETE;
              }
          }
      }
  
      return(status);
  }
  
  
  /* TODO: In APR 2.x: Extend apr_sockaddr_t to possibly be a path !!! */
  PROXY_DECLARE(apr_status_t) ap_proxy_connect_uds(apr_socket_t *sock,
                                                   const char *uds_path,
                                                   apr_pool_t *p)
  {
  #if APR_HAVE_SYS_UN_H
      apr_status_t rv;
      apr_os_sock_t rawsock;
      apr_interval_time_t t;
      struct sockaddr_un *sa;
      apr_socklen_t addrlen, pathlen;
  
      rv = apr_os_sock_get(&rawsock, sock);
      if (rv != APR_SUCCESS) {
          return rv;
      }
  
      rv = apr_socket_timeout_get(sock, &t);
      if (rv != APR_SUCCESS) {
          return rv;
      }
  
      pathlen = strlen(uds_path);
      /* copy the UDS path (including NUL) to the sockaddr_un */
      addrlen = APR_OFFSETOF(struct sockaddr_un, sun_path) + pathlen;
      sa = (struct sockaddr_un *)apr_palloc(p, addrlen + 1);
      memcpy(sa->sun_path, uds_path, pathlen + 1);
      sa->sun_family = AF_UNIX;
  
      do {
          rv = connect(rawsock, (struct sockaddr*)sa, addrlen);
      } while (rv == -1 && (rv = errno) == EINTR);
  
      if (rv && rv != EISCONN) {
          if ((rv == EINPROGRESS || rv == EALREADY) && (t > 0))  {
  #if APR_MAJOR_VERSION < 2
              rv = apr_wait_for_io_or_timeout(NULL, sock, 0);
  #else
              rv = apr_socket_wait(sock, APR_WAIT_WRITE);
  #endif
          }
          if (rv != APR_SUCCESS) {
              return rv;
          }
      }
  
      return APR_SUCCESS;
  #else
      return APR_ENOTIMPL;
  #endif
  }
  
  PROXY_DECLARE(apr_status_t) ap_proxy_check_connection(const char *scheme,
                                                        proxy_conn_rec *conn,
                                                        server_rec *server,
                                                        unsigned max_blank_lines,
                                                        int flags)
  {
      apr_status_t rv = APR_SUCCESS;
      proxy_worker *worker = conn->worker;
  
      if (!PROXY_WORKER_IS_USABLE(worker)) {
          /*
           * The worker is in error likely done by a different thread / process
           * e.g. for a timeout or bad status. We should respect this and should
           * not continue with a connection via this worker even if we got one.
           */
          rv = APR_EINVAL;
      }
      else if (conn->connection) {
          /* We have a conn_rec, check the full filter stack for things like
           * SSL alert/shutdown, filters aside data...
           */
          rv = ap_check_pipeline(conn->connection, conn->tmp_bb,
                                 max_blank_lines);
          apr_brigade_cleanup(conn->tmp_bb);
          if (rv == APR_SUCCESS) {
              /* Some data available, the caller might not want them. */
              if (flags & PROXY_CHECK_CONN_EMPTY) {
                  rv = APR_ENOTEMPTY;
              }
          }
          else if (APR_STATUS_IS_EAGAIN(rv)) {
              /* Filter chain is OK and empty, yet we can't determine from
               * ap_check_pipeline (actually ap_core_input_filter) whether
               * an empty non-blocking read is EAGAIN or EOF on the socket
               * side (it's always SUCCESS), so check it explicitly here.
               */
              if (ap_proxy_is_socket_connected(conn->sock)) {
                  rv = APR_SUCCESS;
              }
              else {
                  rv = APR_EPIPE;
              }
          }
      }
      else if (conn->sock) {
          /* For modules working with sockets directly, check it. */
          if (!ap_proxy_is_socket_connected(conn->sock)) {
              rv = APR_EPIPE;
          }
      }
      else {
          rv = APR_ENOSOCKET;
      }
  
      if (rv == APR_SUCCESS) {
          if (APLOGtrace2(server)) {
              apr_sockaddr_t *local_addr = NULL;
              apr_socket_addr_get(&local_addr, APR_LOCAL, conn->sock);
              ap_log_error(APLOG_MARK, APLOG_TRACE2, 0, server,
                           "%s: reusing backend connection %pI<>%pI",
                           scheme, local_addr, conn->addr);
          }
      }
      else if (conn->sock) {
          /* This clears conn->scpool (and associated data), so backup and
           * restore any ssl_hostname for this connection set earlier by
           * ap_proxy_determine_connection().
           */
          char ssl_hostname[PROXY_WORKER_RFC1035_NAME_SIZE];
          if (rv == APR_EINVAL
                  || !conn->ssl_hostname
                  || PROXY_STRNCPY(ssl_hostname, conn->ssl_hostname)) {
              ssl_hostname[0] = '\0';
          }
  
          socket_cleanup(conn);
          if (rv != APR_ENOTEMPTY) {
              ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, server, APLOGNO(00951)
                           "%s: backend socket is disconnected.", scheme);
          }
          else {
              ap_log_error(APLOG_MARK, APLOG_INFO, 0, server, APLOGNO(03408)
                           "%s: reusable backend connection is not empty: "
                           "forcibly closed", scheme);
          }
  
          if (ssl_hostname[0]) {
              conn->ssl_hostname = apr_pstrdup(conn->scpool, ssl_hostname);
          }
      }
  
      return rv;
  }
  
  PROXY_DECLARE(int) ap_proxy_connect_backend(const char *proxy_function,
                                              proxy_conn_rec *conn,
                                              proxy_worker *worker,
                                              server_rec *s)
  {
      apr_status_t rv;
      int loglevel;
      apr_sockaddr_t *backend_addr = conn->addr;
      /* the local address to use for the outgoing connection */
      apr_sockaddr_t *local_addr;
      apr_socket_t *newsock;
      void *sconf = s->module_config;
      proxy_server_conf *conf =
          (proxy_server_conf *) ap_get_module_config(sconf, &proxy_module);
  
      rv = ap_proxy_check_connection(proxy_function, conn, s, 0, 0);
      if (rv == APR_EINVAL) {
          return DECLINED;
      }
  
      while (rv != APR_SUCCESS && (backend_addr || conn->uds_path)) {
  #if APR_HAVE_SYS_UN_H
          if (conn->uds_path)
          {
              rv = apr_socket_create(&newsock, AF_UNIX, SOCK_STREAM, 0,
                                     conn->scpool);
              if (rv != APR_SUCCESS) {
                  loglevel = APLOG_ERR;
                  ap_log_error(APLOG_MARK, loglevel, rv, s, APLOGNO(02453)
                               "%s: error creating Unix domain socket for "
                               "target %s",
                               proxy_function,
                               worker->s->hostname_ex);
                  break;
              }
              conn->connection = NULL;
  
              rv = ap_proxy_connect_uds(newsock, conn->uds_path, conn->scpool);
              if (rv != APR_SUCCESS) {
                  apr_socket_close(newsock);
                  ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(02454)
                               "%s: attempt to connect to Unix domain socket "
                               "%s (%s) failed",
                               proxy_function,
                               conn->uds_path,
                               worker->s->hostname_ex);
                  break;
              }
  
              ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(02823)
                           "%s: connection established with Unix domain socket "
                           "%s (%s)",
                           proxy_function,
                           conn->uds_path,
                           worker->s->hostname_ex);
          }
          else
  #endif
          {
              if ((rv = apr_socket_create(&newsock, backend_addr->family,
                                          SOCK_STREAM, APR_PROTO_TCP,
                                          conn->scpool)) != APR_SUCCESS) {
                  loglevel = backend_addr->next ? APLOG_DEBUG : APLOG_ERR;
                  ap_log_error(APLOG_MARK, loglevel, rv, s, APLOGNO(00952)
                               "%s: error creating fam %d socket for "
                               "target %s",
                               proxy_function,
                               backend_addr->family,
                               worker->s->hostname_ex);
                  /*
                   * this could be an IPv6 address from the DNS but the
                   * local machine won't give us an IPv6 socket; hopefully the
                   * DNS returned an additional address to try
                   */
                  backend_addr = backend_addr->next;
                  continue;
              }
              conn->connection = NULL;
  
              if (worker->s->recv_buffer_size > 0 &&
                  (rv = apr_socket_opt_set(newsock, APR_SO_RCVBUF,
                                           worker->s->recv_buffer_size))) {
                  ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00953)
                               "apr_socket_opt_set(SO_RCVBUF): Failed to set "
                               "ProxyReceiveBufferSize, using default");
              }
  
              rv = apr_socket_opt_set(newsock, APR_TCP_NODELAY, 1);
              if (rv != APR_SUCCESS && rv != APR_ENOTIMPL) {
                  ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00954)
                               "apr_socket_opt_set(APR_TCP_NODELAY): "
                               "Failed to set");
              }
  
              /* Set a timeout for connecting to the backend on the socket */
              if (worker->s->conn_timeout_set) {
                  apr_socket_timeout_set(newsock, worker->s->conn_timeout);
              }
              else if (worker->s->timeout_set) {
                  apr_socket_timeout_set(newsock, worker->s->timeout);
              }
              else if (conf->timeout_set) {
                  apr_socket_timeout_set(newsock, conf->timeout);
              }
              else {
                  apr_socket_timeout_set(newsock, s->timeout);
              }
              /* Set a keepalive option */
              if (worker->s->keepalive) {
                  if ((rv = apr_socket_opt_set(newsock,
                                               APR_SO_KEEPALIVE, 1)) != APR_SUCCESS) {
                      ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00955)
                                   "apr_socket_opt_set(SO_KEEPALIVE): Failed to set"
                                   " Keepalive");
                  }
              }
              ap_log_error(APLOG_MARK, APLOG_TRACE2, 0, s,
                           "%s: fam %d socket created to connect to %s",
                           proxy_function, backend_addr->family, worker->s->hostname_ex);
  
              if (conf->source_address_set) {
                  local_addr = apr_pmemdup(conn->scpool, conf->source_address,
                                           sizeof(apr_sockaddr_t));
                  local_addr->pool = conn->scpool;
                  rv = apr_socket_bind(newsock, local_addr);
                  if (rv != APR_SUCCESS) {
                      ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00956)
                                   "%s: failed to bind socket to local address",
                                   proxy_function);
                  }
              }
  
              /* make the connection out of the socket */
              rv = apr_socket_connect(newsock, backend_addr);
  
              /* if an error occurred, loop round and try again */
              if (rv != APR_SUCCESS) {
                  apr_socket_close(newsock);
                  loglevel = backend_addr->next ? APLOG_DEBUG : APLOG_ERR;
                  ap_log_error(APLOG_MARK, loglevel, rv, s, APLOGNO(00957)
                               "%s: attempt to connect to %pI (%s) failed",
                               proxy_function,
                               backend_addr,
                               worker->s->hostname_ex);
                  backend_addr = backend_addr->next;
                  continue;
              }
  
              ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(02824)
                           "%s: connection established with %pI (%s)",
                           proxy_function,
                           backend_addr,
                           worker->s->hostname_ex);
          }
  
          /* Set a timeout on the socket */
          if (worker->s->timeout_set) {
              apr_socket_timeout_set(newsock, worker->s->timeout);
          }
          else if (conf->timeout_set) {
              apr_socket_timeout_set(newsock, conf->timeout);
          }
          else {
               apr_socket_timeout_set(newsock, s->timeout);
          }
  
          conn->sock = newsock;
  
          if (!conn->uds_path && conn->forward) {
              forward_info *forward = (forward_info *)conn->forward;
              /*
               * For HTTP CONNECT we need to prepend CONNECT request before
               * sending our actual HTTPS requests.
               */
              if (forward->use_http_connect) {
                  rv = send_http_connect(conn, s);
                  /* If an error occurred, loop round and try again */
                  if (rv != APR_SUCCESS) {
                      conn->sock = NULL;
                      apr_socket_close(newsock);
                      loglevel = backend_addr->next ? APLOG_DEBUG : APLOG_ERR;
                      ap_log_error(APLOG_MARK, loglevel, rv, s, APLOGNO(00958)
                                   "%s: attempt to connect to %s:%d "
                                   "via http CONNECT through %pI (%s) failed",
                                   proxy_function,
                                   forward->target_host, forward->target_port,
                                   backend_addr, worker->s->hostname_ex);
                      backend_addr = backend_addr->next;
                      continue;
                  }
              }
          }
      }
  
      if (PROXY_WORKER_IS_USABLE(worker)) {
          /*
           * Put the entire worker to error state if
           * the PROXY_WORKER_IGNORE_ERRORS flag is not set.
           * Although some connections may be alive
           * no further connections to the worker could be made
           */
          if (rv != APR_SUCCESS) {
              if (!(worker->s->status & PROXY_WORKER_IGNORE_ERRORS)) {
                  worker->s->error_time = apr_time_now();
                  worker->s->status |= PROXY_WORKER_IN_ERROR;
                  ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(00959)
                      "ap_proxy_connect_backend disabling worker for (%s) for %"
                      APR_TIME_T_FMT "s",
                      worker->s->hostname_ex, apr_time_sec(worker->s->retry));
              }
          }
          else {
              if (worker->s->retries) {
                  /*
                   * A worker came back. So here is where we need to
                   * either reset all params to initial conditions or
                   * apply some sort of aging
                   */
              }
              worker->s->error_time = 0;
              worker->s->retries = 0;
          }
      }
      else {
          /*
           * The worker is in error likely done by a different thread / process
           * e.g. for a timeout or bad status. We should respect this and should
           * not continue with a connection via this worker even if we got one.
           */
          if (rv == APR_SUCCESS) {
              socket_cleanup(conn);
          }
          rv = APR_EINVAL;
      }
  
      return rv == APR_SUCCESS ? OK : DECLINED;
  }
  
  static apr_status_t connection_shutdown(void *theconn)
  {
      proxy_conn_rec *conn = (proxy_conn_rec *)theconn;
      conn_rec *c = conn->connection;
      if (c) {
          if (!c->aborted) {
              apr_interval_time_t saved_timeout = 0;
              apr_socket_timeout_get(conn->sock, &saved_timeout);
              if (saved_timeout) {
                  apr_socket_timeout_set(conn->sock, 0);
              }
  
              (void)ap_shutdown_conn(c, 0);
              c->aborted = 1;
  
              if (saved_timeout) {
                  apr_socket_timeout_set(conn->sock, saved_timeout);
              }
          }
  
          ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, c, APLOGNO(02642)
                        "proxy: connection shutdown");
      }
      return APR_SUCCESS;
  }
  
  
  static int proxy_connection_create(const char *proxy_function,
                                     proxy_conn_rec *conn,
                                     request_rec *r, server_rec *s)
  {
      ap_conf_vector_t *per_dir_config = (r) ? r->per_dir_config
                                             : conn->worker->section_config;
      apr_sockaddr_t *backend_addr = conn->addr;
      int rc;
      apr_interval_time_t current_timeout;
      apr_bucket_alloc_t *bucket_alloc;
  
      if (conn->connection) {
          if (conn->is_ssl) {
              /* on reuse, reinit the SSL connection dir config with the current
               * r->per_dir_config, the previous one was reset on release.
               */
              ap_proxy_ssl_engine(conn->connection, per_dir_config, 1);
          }
          return OK;
      }
  
      bucket_alloc = apr_bucket_alloc_create(conn->scpool);
      conn->tmp_bb = apr_brigade_create(conn->scpool, bucket_alloc);
      /*
       * The socket is now open, create a new backend server connection
       */
      conn->connection = ap_run_create_connection(conn->scpool, s, conn->sock,
                                                  0, NULL,
                                                  bucket_alloc);
  
      if (!conn->connection) {
          /*
           * the peer reset the connection already; ap_run_create_connection()
           * closed the socket
           */
          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0,
                       s, APLOGNO(00960) "%s: an error occurred creating a "
                       "new connection to %pI (%s)", proxy_function,
                       backend_addr, conn->hostname);
          /* XXX: Will be closed when proxy_conn is closed */
          socket_cleanup(conn);
          return HTTP_INTERNAL_SERVER_ERROR;
      }
  
      /* For ssl connection to backend */
      if (conn->is_ssl) {
          if (!ap_proxy_ssl_engine(conn->connection, per_dir_config, 1)) {
              ap_log_error(APLOG_MARK, APLOG_ERR, 0,
                           s, APLOGNO(00961) "%s: failed to enable ssl support "
                           "for %pI (%s)", proxy_function,
                           backend_addr, conn->hostname);
              return HTTP_INTERNAL_SERVER_ERROR;
          }
          if (conn->ssl_hostname) {
              /* Set a note on the connection about what CN is requested,
               * such that mod_ssl can check if it is requested to do so.
               */
              ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, conn->connection, 
                            "%s: set SNI to %s for (%s)", proxy_function,
                            conn->ssl_hostname, conn->hostname);
              apr_table_setn(conn->connection->notes, "proxy-request-hostname",
                             conn->ssl_hostname);
          }
      }
      else {
          /* TODO: See if this will break FTP */
          ap_proxy_ssl_engine(conn->connection, per_dir_config, 0);
      }
  
      ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00962)
                   "%s: connection complete to %pI (%s)",
                   proxy_function, backend_addr, conn->hostname);
  
      /*
       * save the timeout of the socket because core_pre_connection
       * will set it to base_server->timeout
       * (core TimeOut directive).
       */
      apr_socket_timeout_get(conn->sock, &current_timeout);
      /* set up the connection filters */
      rc = ap_run_pre_connection(conn->connection, conn->sock);
      if (rc != OK && rc != DONE) {
          conn->connection->aborted = 1;
          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00963)
                       "%s: pre_connection setup failed (%d)",
                       proxy_function, rc);
          return rc;
      }
      apr_socket_timeout_set(conn->sock, current_timeout);
  
      /* Shutdown the connection before closing it (eg. SSL connections
       * need to be close-notify-ed).
       */
      apr_pool_pre_cleanup_register(conn->scpool, conn, connection_shutdown);
  
      return OK;
  }
  
  PROXY_DECLARE(int) ap_proxy_connection_create_ex(const char *proxy_function,
                                                   proxy_conn_rec *conn,
                                                   request_rec *r)
  {
      return proxy_connection_create(proxy_function, conn, r, r->server);
  }
  
  PROXY_DECLARE(int) ap_proxy_connection_create(const char *proxy_function,
                                                proxy_conn_rec *conn,
                                                conn_rec *c, server_rec *s)
  {
      (void) c; /* unused */
      return proxy_connection_create(proxy_function, conn, NULL, s);
  }
  
  int ap_proxy_lb_workers(void)
  {
      /*
       * Since we can't resize the scoreboard when reconfiguring, we
       * have to impose a limit on the number of workers, we are
       * able to reconfigure to.
       */
      if (!lb_workers_limit)
          lb_workers_limit = proxy_lb_workers + PROXY_DYNAMIC_BALANCER_LIMIT;
      return lb_workers_limit;
  }
  
  static APR_INLINE int error_code_overridden(const int *elts, int nelts,
                                              int code)
  {
      int min = 0;
      int max = nelts - 1;
      AP_DEBUG_ASSERT(max >= 0);
  
      while (min < max) {
          int mid = (min + max) / 2;
          int val = elts[mid];
  
          if (val < code) {
              min = mid + 1;
          }
          else if (val > code) {
              max = mid - 1;
          }
          else {
              return 1;
          }
      }
  
      return elts[min] == code;
  }
  
  PROXY_DECLARE(int) ap_proxy_should_override(proxy_dir_conf *conf, int code)
  {
      if (!conf->error_override) 
          return 0;
  
      if (apr_is_empty_array(conf->error_override_codes))
          return ap_is_HTTP_ERROR(code);
  
      /* Since error_override_codes is sorted, apply binary search. */
      return error_code_overridden((int *)conf->error_override_codes->elts,
                                   conf->error_override_codes->nelts,
                                   code);
  }
  
  /* deprecated - to be removed in v2.6 */
  PROXY_DECLARE(void) ap_proxy_backend_broke(request_rec *r,
                                             apr_bucket_brigade *brigade)
  {
      apr_bucket *e;
      conn_rec *c = r->connection;
  
      r->no_cache = 1;
      /*
       * If this is a subrequest, then prevent also caching of the main
       * request.
       */
      if (r->main)
          r->main->no_cache = 1;
      e = ap_bucket_error_create(HTTP_GATEWAY_TIME_OUT, NULL, c->pool,
                                 c->bucket_alloc);
      APR_BRIGADE_INSERT_TAIL(brigade, e);
      e = apr_bucket_eos_create(c->bucket_alloc);
      APR_BRIGADE_INSERT_TAIL(brigade, e);
  }
  
  /*
   * Provide a string hashing function for the proxy.
   * We offer 2 methods: one is the APR model but we
   * also provide our own, based on either FNV or SDBM.
   * The reason is in case we want to use both to ensure no
   * collisions.
   */
  PROXY_DECLARE(unsigned int)
  ap_proxy_hashfunc(const char *str, proxy_hash_t method)
  {
      if (method == PROXY_HASHFUNC_APR) {
          apr_ssize_t slen = strlen(str);
          return apr_hashfunc_default(str, &slen);
      }
      else if (method == PROXY_HASHFUNC_FNV) {
          /* FNV model */
          unsigned int hash;
          const unsigned int fnv_prime = 0x811C9DC5;
          for (hash = 0; *str; str++) {
              hash *= fnv_prime;
              hash ^= (*str);
          }
          return hash;
      }
      else { /* method == PROXY_HASHFUNC_DEFAULT */
          /* SDBM model */
          unsigned int hash;
          for (hash = 0; *str; str++) {
              hash = (*str) + (hash << 6) + (hash << 16) - hash;
          }
          return hash;
      }
  }
  
  PROXY_DECLARE(apr_status_t) ap_proxy_set_wstatus(char c, int set, proxy_worker *w)
  {
      unsigned int *status = &w->s->status;
      char flag = toupper(c);
      proxy_wstat_t *pwt = proxy_wstat_tbl;
      while (pwt->bit) {
          if (flag == pwt->flag) {
              if (set)
                  *status |= pwt->bit;
              else
                  *status &= ~(pwt->bit);
              return APR_SUCCESS;
          }
          pwt++;
      }
      return APR_EINVAL;
  }
  
  PROXY_DECLARE(char *) ap_proxy_parse_wstatus(apr_pool_t *p, proxy_worker *w)
  {
      char *ret = "";
      unsigned int status = w->s->status;
      proxy_wstat_t *pwt = proxy_wstat_tbl;
      while (pwt->bit) {
          if (status & pwt->bit)
              ret = apr_pstrcat(p, ret, pwt->name, NULL);
          pwt++;
      }
      if (!*ret) {
          ret = "??? ";
      }
      if (PROXY_WORKER_IS_USABLE(w))
          ret = apr_pstrcat(p, ret, "Ok ", NULL);
      return ret;
  }
  
  PROXY_DECLARE(apr_status_t) ap_proxy_sync_balancer(proxy_balancer *b, server_rec *s,
                                                      proxy_server_conf *conf)
  {
      proxy_worker **workers;
      int i;
      int index;
      proxy_worker_shared *shm;
      proxy_balancer_method *lbmethod;
      ap_slotmem_provider_t *storage = b->storage;
  
      if (b->s->wupdated <= b->wupdated)
          return APR_SUCCESS;
      /* balancer sync */
      lbmethod = ap_lookup_provider(PROXY_LBMETHOD, b->s->lbpname, "0");
      if (lbmethod) {
          b->lbmethod = lbmethod;
      } else {
          ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(02433)
                       "Cannot find LB Method: %s", b->s->lbpname);
          return APR_EINVAL;
      }
  
      /* worker sync */
  
      /*
       * Look thru the list of workers in shm
       * and see which one(s) we are lacking...
       * again, the cast to unsigned int is safe
       * since our upper limit is always max_workers
       * which is int.
       */
      for (index = 0; index < b->max_workers; index++) {
          int found;
          apr_status_t rv;
          if ((rv = storage->dptr(b->wslot, (unsigned int)index, (void *)&shm)) != APR_SUCCESS) {
              ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(00965) "worker slotmem_dptr failed");
              return APR_EGENERAL;
          }
          /* account for possible "holes" in the slotmem
           * (eg: slots 0-2 are used, but 3 isn't, but 4-5 is)
           */
          if (!shm->hash.def || !shm->hash.fnv)
              continue;
          found = 0;
          workers = (proxy_worker **)b->workers->elts;
          for (i = 0; i < b->workers->nelts; i++, workers++) {
              proxy_worker *worker = *workers;
              if (worker->hash.def == shm->hash.def && worker->hash.fnv == shm->hash.fnv) {
                  found = 1;
                  ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(02402)
                               "re-grabbing shm[%d] (0x%pp) for worker: %s", i, (void *)shm,
                               ap_proxy_worker_name(conf->pool, worker));
                  break;
              }
          }
          if (!found) {
              proxy_worker **runtime;
              apr_global_mutex_lock(proxy_mutex);
              runtime = apr_array_push(b->workers);
              *runtime = apr_palloc(conf->pool, sizeof(proxy_worker));
              apr_global_mutex_unlock(proxy_mutex);
              (*runtime)->hash = shm->hash;
              (*runtime)->context = NULL;
              (*runtime)->cp = NULL;
              (*runtime)->balancer = b;
              (*runtime)->s = shm;
  #if APR_HAS_THREADS
              (*runtime)->tmutex = NULL;
  #endif
              rv = ap_proxy_initialize_worker(*runtime, s, conf->pool);
              if (rv != APR_SUCCESS) {
                  ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(00966) "Cannot init worker");
                  return rv;
              }
              ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(02403)
                           "grabbing shm[%d] (0x%pp) for worker: %s", i, (void *)shm,
                           (*runtime)->s->name);
          }
      }
      if (b->s->need_reset) {
          if (b->lbmethod && b->lbmethod->reset)
              b->lbmethod->reset(b, s);
          b->s->need_reset = 0;
      }
      b->wupdated = b->s->wupdated;
      return APR_SUCCESS;
  }
  
  PROXY_DECLARE(proxy_worker_shared *) ap_proxy_find_workershm(ap_slotmem_provider_t *storage,
                                                                 ap_slotmem_instance_t *slot,
                                                                 proxy_worker *worker,
                                                                 unsigned int *index)
  {
      proxy_worker_shared *shm;
      unsigned int i, limit;
      limit = storage->num_slots(slot);
      for (i = 0; i < limit; i++) {
          if (storage->dptr(slot, i, (void *)&shm) != APR_SUCCESS) {
              return NULL;
          }
          if ((worker->s->hash.def == shm->hash.def) &&
              (worker->s->hash.fnv == shm->hash.fnv)) {
              *index = i;
              return shm;
          }
      }
      return NULL;
  }
  
  PROXY_DECLARE(proxy_balancer_shared *) ap_proxy_find_balancershm(ap_slotmem_provider_t *storage,
                                                                   ap_slotmem_instance_t *slot,
                                                                   proxy_balancer *balancer,
                                                                   unsigned int *index)
  {
      proxy_balancer_shared *shm;
      unsigned int i, limit;
      limit = storage->num_slots(slot);
      for (i = 0; i < limit; i++) {
          if (storage->dptr(slot, i, (void *)&shm) != APR_SUCCESS) {
              return NULL;
          }
          if ((balancer->s->hash.def == shm->hash.def) &&
              (balancer->s->hash.fnv == shm->hash.fnv)) {
              *index = i;
              return shm;
          }
      }
      return NULL;
  }
  
  typedef struct header_connection {
      apr_pool_t *pool;
      apr_array_header_t *array;
      const char *error;
      int is_req;
  } header_connection;
  
  static int find_conn_headers(void *data, const char *key, const char *val)
  {
      header_connection *x = data;
      x->error = ap_parse_token_list_strict(x->pool, val, &x->array, !x->is_req);
      return !x->error;
  }
  
  /**
   * Remove all headers referred to by the Connection header.
   * Returns -1 on error. Otherwise, returns 1 if 'Close' was seen in
   * the Connection header tokens, and 0 if not.
   */
  static int ap_proxy_clear_connection(request_rec *r, apr_table_t *headers)
  {
      int closed = 0;
      header_connection x;
  
      x.pool = r->pool;
      x.array = NULL;
      x.error = NULL;
      x.is_req = (headers == r->headers_in);
  
      apr_table_unset(headers, "Proxy-Connection");
  
      apr_table_do(find_conn_headers, &x, headers, "Connection", NULL);
      apr_table_unset(headers, "Connection");
  
      if (x.error) {
          ap_log_rerror(APLOG_MARK, APLOG_NOTICE, 0, r, APLOGNO(02806)
                  "Error parsing Connection header: %s", x.error);
          return -1;
      }
  
      if (x.array) {
          int i;
          for (i = 0; i < x.array->nelts; i++) {
              const char *name = APR_ARRAY_IDX(x.array, i, const char *);
              ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02807)
                            "Removing header '%s' listed in Connection header",
                            name);
              if (!ap_cstr_casecmp(name, "close")) {
                  closed = 1;
              }
              apr_table_unset(headers, name);
          }
      }
  
      return closed;
  }
  
  PROXY_DECLARE(int) ap_proxy_create_hdrbrgd(apr_pool_t *p,
                                              apr_bucket_brigade *header_brigade,
                                              request_rec *r,
                                              proxy_conn_rec *p_conn,
                                              proxy_worker *worker,
                                              proxy_server_conf *conf,
                                              apr_uri_t *uri,
                                              char *url, char *server_portstr,
                                              char **old_cl_val,
                                              char **old_te_val)
  {
      conn_rec *c = r->connection;
      int counter;
      char *buf;
      const apr_array_header_t *headers_in_array;
      const apr_table_entry_t *headers_in;
      apr_table_t *saved_headers_in;
      apr_bucket *e;
      int do_100_continue;
      conn_rec *origin = p_conn->connection;
      const char *fpr1;
      proxy_dir_conf *dconf = ap_get_module_config(r->per_dir_config, &proxy_module);
  
      /*
       * HTTP "Ping" test? Easiest is 100-Continue. However:
       * To be compliant, we only use 100-Continue for requests with bodies.
       * We also make sure we won't be talking HTTP/1.0 as well.
       */
      fpr1 = apr_table_get(r->subprocess_env, "force-proxy-request-1.0");
      do_100_continue = PROXY_DO_100_CONTINUE(worker, r);
  
      if (fpr1) {
          /*
           * According to RFC 2616 8.2.3 we are not allowed to forward an
           * Expect: 100-continue to an HTTP/1.0 server. Instead we MUST return
           * a HTTP_EXPECTATION_FAILED
           */
          if (r->expecting_100) {
              return HTTP_EXPECTATION_FAILED;
          }
          buf = apr_pstrcat(p, r->method, " ", url, " HTTP/1.0" CRLF, NULL);
          p_conn->close = 1;
      } else {
          buf = apr_pstrcat(p, r->method, " ", url, " HTTP/1.1" CRLF, NULL);
      }
      if (apr_table_get(r->subprocess_env, "proxy-nokeepalive")) {
          if (origin) {
              origin->keepalive = AP_CONN_CLOSE;
          }
          p_conn->close = 1;
      }
      ap_xlate_proto_to_ascii(buf, strlen(buf));
      e = apr_bucket_pool_create(buf, strlen(buf), p, c->bucket_alloc);
      APR_BRIGADE_INSERT_TAIL(header_brigade, e);
      if (dconf->preserve_host == 0) {
          if (ap_strchr_c(uri->hostname, ':')) { /* if literal IPv6 address */
              if (uri->port_str && uri->port != DEFAULT_HTTP_PORT) {
                  buf = apr_pstrcat(p, "Host: [", uri->hostname, "]:",
                                    uri->port_str, CRLF, NULL);
              } else {
                  buf = apr_pstrcat(p, "Host: [", uri->hostname, "]", CRLF, NULL);
              }
          } else {
              if (uri->port_str && uri->port != DEFAULT_HTTP_PORT) {
                  buf = apr_pstrcat(p, "Host: ", uri->hostname, ":",
                                    uri->port_str, CRLF, NULL);
              } else {
                  buf = apr_pstrcat(p, "Host: ", uri->hostname, CRLF, NULL);
              }
          }
      }
      else {
          /* don't want to use r->hostname, as the incoming header might have a
           * port attached
           */
          const char* hostname = apr_table_get(r->headers_in,"Host");
          if (!hostname) {
              hostname =  r->server->server_hostname;
              ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(01092)
                            "no HTTP 0.9 request (with no host line) "
                            "on incoming request and preserve host set "
                            "forcing hostname to be %s for uri %s",
                            hostname, r->uri);
          }
          buf = apr_pstrcat(p, "Host: ", hostname, CRLF, NULL);
      }
      ap_xlate_proto_to_ascii(buf, strlen(buf));
      e = apr_bucket_pool_create(buf, strlen(buf), p, c->bucket_alloc);
      APR_BRIGADE_INSERT_TAIL(header_brigade, e);
  
      /*
       * Save the original headers in here and restore them when leaving, since
       * we will apply proxy purpose only modifications (eg. clearing hop-by-hop
       * headers, add Via or X-Forwarded-* or Expect...), whereas the originals
       * will be needed later to prepare the correct response and logging.
       *
       * Note: We need to take r->pool for apr_table_copy as the key / value
       * pairs in r->headers_in have been created out of r->pool and
       * p might be (and actually is) a longer living pool.
       * This would trigger the bad pool ancestry abort in apr_table_copy if
       * apr is compiled with APR_POOL_DEBUG.
       */
      saved_headers_in = r->headers_in;
      r->headers_in = apr_table_copy(r->pool, saved_headers_in);
  
      /* handle Via */
      if (conf->viaopt == via_block) {
          /* Block all outgoing Via: headers */
          apr_table_unset(r->headers_in, "Via");
      } else if (conf->viaopt != via_off) {
          const char *server_name = ap_get_server_name(r);
          /* If USE_CANONICAL_NAME_OFF was configured for the proxy virtual host,
           * then the server name returned by ap_get_server_name() is the
           * origin server name (which does make too much sense with Via: headers)
           * so we use the proxy vhost's name instead.
           */
          if (server_name == r->hostname)
              server_name = r->server->server_hostname;
          /* Create a "Via:" request header entry and merge it */
          /* Generate outgoing Via: header with/without server comment: */
          apr_table_mergen(r->headers_in, "Via",
                           (conf->viaopt == via_full)
                           ? apr_psprintf(p, "%d.%d %s%s (%s)",
                                          HTTP_VERSION_MAJOR(r->proto_num),
                                          HTTP_VERSION_MINOR(r->proto_num),
                                          server_name, server_portstr,
                                          AP_SERVER_BASEVERSION)
                           : apr_psprintf(p, "%d.%d %s%s",
                                          HTTP_VERSION_MAJOR(r->proto_num),
                                          HTTP_VERSION_MINOR(r->proto_num),
                                          server_name, server_portstr)
                           );
      }
  
      /* Use HTTP/1.1 100-Continue as quick "HTTP ping" test
       * to backend
       */
      if (do_100_continue) {
          const char *val;
  
          /* Add the Expect header if not already there. */
          if (((val = apr_table_get(r->headers_in, "Expect")) == NULL)
                  || (ap_cstr_casecmp(val, "100-Continue") != 0 /* fast path */
                      && !ap_find_token(r->pool, val, "100-Continue"))) {
              apr_table_mergen(r->headers_in, "Expect", "100-Continue");
          }
      }
  
      /* X-Forwarded-*: handling
       *
       * XXX Privacy Note:
       * -----------------
       *
       * These request headers are only really useful when the mod_proxy
       * is used in a reverse proxy configuration, so that useful info
       * about the client can be passed through the reverse proxy and on
       * to the backend server, which may require the information to
       * function properly.
       *
       * In a forward proxy situation, these options are a potential
       * privacy violation, as information about clients behind the proxy
       * are revealed to arbitrary servers out there on the internet.
       *
       * The HTTP/1.1 Via: header is designed for passing client
       * information through proxies to a server, and should be used in
       * a forward proxy configuration instead of X-Forwarded-*. See the
       * ProxyVia option for details.
       */
      if (dconf->add_forwarded_headers) {
          if (PROXYREQ_REVERSE == r->proxyreq) {
              const char *buf;
  
              /* Add X-Forwarded-For: so that the upstream has a chance to
               * determine, where the original request came from.
               */
              apr_table_mergen(r->headers_in, "X-Forwarded-For",
                               r->useragent_ip);
  
              /* Add X-Forwarded-Host: so that upstream knows what the
               * original request hostname was.
               */
              if ((buf = apr_table_get(r->headers_in, "Host"))) {
                  apr_table_mergen(r->headers_in, "X-Forwarded-Host", buf);
              }
  
              /* Add X-Forwarded-Server: so that upstream knows what the
               * name of this proxy server is (if there are more than one)
               * XXX: This duplicates Via: - do we strictly need it?
               */
              apr_table_mergen(r->headers_in, "X-Forwarded-Server",
                               r->server->server_hostname);
          }
      }
  
      proxy_run_fixups(r);
      if (ap_proxy_clear_connection(r, r->headers_in) < 0) {
          return HTTP_BAD_REQUEST;
      }
  
      /* send request headers */
      headers_in_array = apr_table_elts(r->headers_in);
      headers_in = (const apr_table_entry_t *) headers_in_array->elts;
      for (counter = 0; counter < headers_in_array->nelts; counter++) {
          if (headers_in[counter].key == NULL
              || headers_in[counter].val == NULL
  
              /* Already sent */
              || !ap_cstr_casecmp(headers_in[counter].key, "Host")
  
              /* Clear out hop-by-hop request headers not to send
               * RFC2616 13.5.1 says we should strip these headers
               */
              || !ap_cstr_casecmp(headers_in[counter].key, "Keep-Alive")
              || !ap_cstr_casecmp(headers_in[counter].key, "TE")
              || !ap_cstr_casecmp(headers_in[counter].key, "Trailer")
              || !ap_cstr_casecmp(headers_in[counter].key, "Upgrade")
  
              ) {
              continue;
          }
          /* Do we want to strip Proxy-Authorization ?
           * If we haven't used it, then NO
           * If we have used it then MAYBE: RFC2616 says we MAY propagate it.
           * So let's make it configurable by env.
           */
          if (!ap_cstr_casecmp(headers_in[counter].key,"Proxy-Authorization")) {
              if (r->user != NULL) { /* we've authenticated */
                  if (!apr_table_get(r->subprocess_env, "Proxy-Chain-Auth")) {
                      continue;
                  }
              }
          }
  
          /* Skip Transfer-Encoding and Content-Length for now.
           */
          if (!ap_cstr_casecmp(headers_in[counter].key, "Transfer-Encoding")) {
              *old_te_val = headers_in[counter].val;
              continue;
          }
          if (!ap_cstr_casecmp(headers_in[counter].key, "Content-Length")) {
              *old_cl_val = headers_in[counter].val;
              continue;
          }
  
          /* for sub-requests, ignore freshness/expiry headers */
          if (r->main) {
              if (   !ap_cstr_casecmp(headers_in[counter].key, "If-Match")
                  || !ap_cstr_casecmp(headers_in[counter].key, "If-Modified-Since")
                  || !ap_cstr_casecmp(headers_in[counter].key, "If-Range")
                  || !ap_cstr_casecmp(headers_in[counter].key, "If-Unmodified-Since")
                  || !ap_cstr_casecmp(headers_in[counter].key, "If-None-Match")) {
                  continue;
              }
          }
  
          buf = apr_pstrcat(p, headers_in[counter].key, ": ",
                            headers_in[counter].val, CRLF,
                            NULL);
          ap_xlate_proto_to_ascii(buf, strlen(buf));
          e = apr_bucket_pool_create(buf, strlen(buf), p, c->bucket_alloc);
          APR_BRIGADE_INSERT_TAIL(header_brigade, e);
      }
  
      /* Restore the original headers in (see comment above),
       * we won't modify them anymore.
       */
      r->headers_in = saved_headers_in;
      return OK;
  }
  
  PROXY_DECLARE(int) ap_proxy_pass_brigade(apr_bucket_alloc_t *bucket_alloc,
                                           request_rec *r, proxy_conn_rec *p_conn,
                                           conn_rec *origin, apr_bucket_brigade *bb,
                                           int flush)
  {
      apr_status_t status;
      apr_off_t transferred;
  
      if (flush) {
          apr_bucket *e = apr_bucket_flush_create(bucket_alloc);
          APR_BRIGADE_INSERT_TAIL(bb, e);
      }
      apr_brigade_length(bb, 0, &transferred);
      if (transferred != -1)
          p_conn->worker->s->transferred += transferred;
      status = ap_pass_brigade(origin->output_filters, bb);
      /* Cleanup the brigade now to avoid buckets lifetime
       * issues in case of error returned below. */
      apr_brigade_cleanup(bb);
      if (status != APR_SUCCESS) {
          ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(01084)
                        "pass request body failed to %pI (%s)",
                        p_conn->addr, p_conn->hostname);
          if (origin->aborted) {
              const char *ssl_note;
  
              if (((ssl_note = apr_table_get(origin->notes, "SSL_connect_rv"))
                   != NULL) && (strcmp(ssl_note, "err") == 0)) {
                  return ap_proxyerror(r, HTTP_INTERNAL_SERVER_ERROR,
                                       "Error during SSL Handshake with"
                                       " remote server");
              }
              return HTTP_GATEWAY_TIME_OUT;
          }
          else {
              return HTTP_BAD_REQUEST;
          }
      }
      return OK;
  }
  
  /* Fill in unknown schemes from apr_uri_port_of_scheme() */
  
  typedef struct proxy_schemes_t {
      const char *name;
      apr_port_t default_port;
  } proxy_schemes_t ;
  
  static proxy_schemes_t pschemes[] =
  {
      {"fcgi",     8000},
      {"ajp",      AJP13_DEF_PORT},
      {"scgi",     SCGI_DEF_PORT},
      {"h2c",      DEFAULT_HTTP_PORT},
      {"h2",       DEFAULT_HTTPS_PORT},
      {"ws",       DEFAULT_HTTP_PORT},
      {"wss",      DEFAULT_HTTPS_PORT},
      { NULL, 0xFFFF }     /* unknown port */
  };
  
  PROXY_DECLARE(apr_port_t) ap_proxy_port_of_scheme(const char *scheme)
  {
      if (scheme) {
          apr_port_t port;
          if ((port = apr_uri_port_of_scheme(scheme)) != 0) {
              return port;
          } else {
              proxy_schemes_t *pscheme;
              for (pscheme = pschemes; pscheme->name != NULL; ++pscheme) {
                  if (ap_cstr_casecmp(scheme, pscheme->name) == 0) {
                      return pscheme->default_port;
                  }
              }
          }
      }
      return 0;
  }
  
  PROXY_DECLARE(apr_status_t) ap_proxy_buckets_lifetime_transform(request_rec *r,
                                                        apr_bucket_brigade *from,
                                                        apr_bucket_brigade *to)
  {
      apr_bucket *e;
      apr_bucket *new;
      const char *data;
      apr_size_t bytes;
      apr_status_t rv = APR_SUCCESS;
      apr_bucket_alloc_t *bucket_alloc = to->bucket_alloc;
  
      apr_brigade_cleanup(to);
      for (e = APR_BRIGADE_FIRST(from);
           e != APR_BRIGADE_SENTINEL(from);
           e = APR_BUCKET_NEXT(e)) {
          if (!APR_BUCKET_IS_METADATA(e)) {
              apr_bucket_read(e, &data, &bytes, APR_BLOCK_READ);
              new = apr_bucket_transient_create(data, bytes, bucket_alloc);
              APR_BRIGADE_INSERT_TAIL(to, new);
          }
          else if (APR_BUCKET_IS_FLUSH(e)) {
              new = apr_bucket_flush_create(bucket_alloc);
              APR_BRIGADE_INSERT_TAIL(to, new);
          }
          else if (APR_BUCKET_IS_EOS(e)) {
              new = apr_bucket_eos_create(bucket_alloc);
              APR_BRIGADE_INSERT_TAIL(to, new);
          }
          else {
              ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(03304)
                            "Unhandled bucket type of type %s in"
                            " ap_proxy_buckets_lifetime_transform", e->type->name);
              rv = APR_EGENERAL;
          }
      }
      return rv;
  }
  
  PROXY_DECLARE(apr_status_t) ap_proxy_transfer_between_connections(
                                                         request_rec *r,
                                                         conn_rec *c_i,
                                                         conn_rec *c_o,
                                                         apr_bucket_brigade *bb_i,
                                                         apr_bucket_brigade *bb_o,
                                                         const char *name,
                                                         int *sent,
                                                         apr_off_t bsize,
                                                         int flags)
  {
      apr_status_t rv;
      int flush_each = 0;
  #ifdef DEBUGGING
      apr_off_t len;
  #endif
  
      /*
       * Compat: since FLUSH_EACH is default (and zero) for legacy reasons, we
       * pretend it's no FLUSH_AFTER nor SHOULD_YIELD flags, the latter because
       * flushing would defeat the purpose of checking for pending data (hence
       * determine whether or not the output chain/stack is full for stopping).
       */
      if (!(flags & (AP_PROXY_TRANSFER_FLUSH_AFTER |
                     AP_PROXY_TRANSFER_SHOULD_YIELD))) {
          flush_each = 1;
      }
  
      do {
          apr_brigade_cleanup(bb_i);
          rv = ap_get_brigade(c_i->input_filters, bb_i, AP_MODE_READBYTES,
                              APR_NONBLOCK_READ, bsize);
          if (rv == APR_SUCCESS) {
              if (c_o->aborted) {
                  apr_brigade_cleanup(bb_i);
                  flags &= ~AP_PROXY_TRANSFER_FLUSH_AFTER;
                  rv = APR_EPIPE;
                  break;
              }
              if (APR_BRIGADE_EMPTY(bb_i)) {
                  break;
              }
  #ifdef DEBUGGING
              len = -1;
              apr_brigade_length(bb_i, 0, &len);
              ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(03306)
                            "ap_proxy_transfer_between_connections: "
                            "read %" APR_OFF_T_FMT
                            " bytes from %s", len, name);
  #endif
              if (sent) {
                  *sent = 1;
              }
              ap_proxy_buckets_lifetime_transform(r, bb_i, bb_o);
              if (flush_each) {
                  apr_bucket *b;
  
                  /*
                   * Do not use ap_fflush here since this would cause the flush
                   * bucket to be sent in a separate brigade afterwards which
                   * causes some filters to set aside the buckets from the first
                   * brigade and process them when FLUSH arrives in the second
                   * brigade. As set asides of our transformed buckets involve
                   * memory copying we try to avoid this. If we have the flush
                   * bucket in the first brigade they directly process the
                   * buckets without setting them aside.
                   */
                  b = apr_bucket_flush_create(bb_o->bucket_alloc);
                  APR_BRIGADE_INSERT_TAIL(bb_o, b);
              }
              rv = ap_pass_brigade(c_o->output_filters, bb_o);
              if (rv != APR_SUCCESS) {
                  ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(03307)
                                "ap_proxy_transfer_between_connections: "
                                "error on %s - ap_pass_brigade",
                                name);
                  flags &= ~AP_PROXY_TRANSFER_FLUSH_AFTER;
              }
              else if ((flags & AP_PROXY_TRANSFER_SHOULD_YIELD) &&
                       ap_filter_should_yield(c_o->output_filters)) {
                  ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                                "ap_proxy_transfer_between_connections: "
                                "output filters full");
                  flags &= ~AP_PROXY_TRANSFER_FLUSH_AFTER;
                  rv = APR_INCOMPLETE;
              }
              apr_brigade_cleanup(bb_o);
          }
          else if (!APR_STATUS_IS_EAGAIN(rv) && !APR_STATUS_IS_EOF(rv)) {
              ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv, r, APLOGNO(03308)
                            "ap_proxy_transfer_between_connections: "
                            "error on %s - ap_get_brigade",
                            name);
          }
      } while (rv == APR_SUCCESS);
  
      if (flags & AP_PROXY_TRANSFER_FLUSH_AFTER) {
          ap_fflush(c_o->output_filters, bb_o);
          apr_brigade_cleanup(bb_o);
      }
      apr_brigade_cleanup(bb_i);
  
      ap_log_rerror(APLOG_MARK, APLOG_TRACE2, rv, r,
                    "ap_proxy_transfer_between_connections complete");
  
      if (APR_STATUS_IS_EAGAIN(rv)) {
          rv = APR_SUCCESS;
      }
  
      return rv;
  }
  
  struct proxy_tunnel_conn {
      conn_rec *c;
      const char *name;
      apr_pollfd_t *pfd;
      apr_bucket_brigade *bb;
      struct proxy_tunnel_conn *other;
      unsigned int readable:1,
                   drain:1;
  };
  
  PROXY_DECLARE(apr_status_t) ap_proxy_tunnel_create(proxy_tunnel_rec **ptunnel,
                                                     request_rec *r, conn_rec *c_o,
                                                     const char *scheme)
  {
      apr_status_t rv;
      conn_rec *c_i = r->connection;
      proxy_tunnel_rec *tunnel;
  
      *ptunnel = NULL;
  
      tunnel = apr_pcalloc(r->pool, sizeof(*tunnel));
  
      rv = apr_pollset_create(&tunnel->pollset, 2, r->pool, APR_POLLSET_NOCOPY);
      if (rv != APR_SUCCESS) {
          return rv;
      }
  
      tunnel->r = r;
      tunnel->scheme = apr_pstrdup(r->pool, scheme);
      tunnel->client = apr_pcalloc(r->pool, sizeof(struct proxy_tunnel_conn));
      tunnel->origin = apr_pcalloc(r->pool, sizeof(struct proxy_tunnel_conn));
      tunnel->pfds = apr_array_make(r->pool, 2, sizeof(apr_pollfd_t));
      tunnel->timeout = -1;
  
      tunnel->client->c = c_i;
      tunnel->client->name = "client";
      tunnel->client->bb = apr_brigade_create(c_i->pool, c_i->bucket_alloc);
      tunnel->client->pfd = &APR_ARRAY_PUSH(tunnel->pfds, apr_pollfd_t);
      memset(tunnel->client->pfd, 0, sizeof(*tunnel->client->pfd));
      tunnel->client->pfd->p = r->pool;
      tunnel->client->pfd->desc_type = APR_POLL_SOCKET;
      tunnel->client->pfd->desc.s = ap_get_conn_socket(c_i);
      tunnel->client->pfd->client_data = tunnel->client;
      tunnel->client->other = tunnel->origin;
      tunnel->client->readable = 1;
  
      tunnel->origin->c = c_o;
      tunnel->origin->name = "origin";
      tunnel->origin->bb = apr_brigade_create(c_o->pool, c_o->bucket_alloc);
      tunnel->origin->pfd = &APR_ARRAY_PUSH(tunnel->pfds, apr_pollfd_t);
      memset(tunnel->origin->pfd, 0, sizeof(*tunnel->origin->pfd));
      tunnel->origin->pfd->p = r->pool;
      tunnel->origin->pfd->desc_type = APR_POLL_SOCKET;
      tunnel->origin->pfd->desc.s = ap_get_conn_socket(c_o);
      tunnel->origin->pfd->client_data = tunnel->origin;
      tunnel->origin->other = tunnel->client;
      tunnel->origin->readable = 1;
  
  #if 0
      apr_socket_opt_set(tunnel->client->pfd->desc.s, APR_SO_NONBLOCK, 1);
      apr_socket_opt_set(tunnel->client->pfd->desc.s, APR_SO_NONBLOCK, 1);
      apr_socket_opt_set(tunnel->origin->pfd->desc.s, APR_SO_KEEPALIVE, 1);
      apr_socket_opt_set(tunnel->origin->pfd->desc.s, APR_SO_KEEPALIVE, 1);
  #endif
  
      /* No coalescing filters */
      ap_remove_output_filter_byhandle(c_i->output_filters,
                                       "SSL/TLS Coalescing Filter");
      ap_remove_output_filter_byhandle(c_o->output_filters,
                                       "SSL/TLS Coalescing Filter");
  
      /* The input/output filter stacks should contain connection filters only */
      r->input_filters = r->proto_input_filters = c_i->input_filters;
      r->output_filters = r->proto_output_filters = c_i->output_filters;
  
      c_i->keepalive = AP_CONN_CLOSE;
      c_o->keepalive = AP_CONN_CLOSE;
  
      *ptunnel = tunnel;
      return APR_SUCCESS;
  }
  
  static void add_pollset(apr_pollset_t *pollset, apr_pollfd_t *pfd,
                          apr_int16_t events)
  {
      apr_status_t rv;
  
      if (events & APR_POLLIN) {
          events |= APR_POLLHUP;
      }
  
      if ((pfd->reqevents & events) == events) {
          return;
      }
  
      if (pfd->reqevents) {
          rv = apr_pollset_remove(pollset, pfd);
          if (rv != APR_SUCCESS) {
              AP_DEBUG_ASSERT(1);
          }
      }
  
      pfd->reqevents |= events;
      rv = apr_pollset_add(pollset, pfd);
      if (rv != APR_SUCCESS) {
          AP_DEBUG_ASSERT(1);
      }
  }
  
  static void del_pollset(apr_pollset_t *pollset, apr_pollfd_t *pfd,
                          apr_int16_t events)
  {
      apr_status_t rv;
  
      if (events & APR_POLLIN) {
          events |= APR_POLLHUP;
      }
  
      if ((pfd->reqevents & events) == 0) {
          return;
      }
  
      rv = apr_pollset_remove(pollset, pfd);
      if (rv != APR_SUCCESS) {
          AP_DEBUG_ASSERT(1);
      }
  
      pfd->reqevents &= ~events;
      if (pfd->reqevents) {
          rv = apr_pollset_add(pollset, pfd);
          if (rv != APR_SUCCESS) {
              AP_DEBUG_ASSERT(1);
          }
      }
  }
  
  PROXY_DECLARE(int) ap_proxy_tunnel_run(proxy_tunnel_rec *tunnel)
  {
      int rc = OK;
      request_rec *r = tunnel->r;
      apr_pollset_t *pollset = tunnel->pollset;
      apr_interval_time_t timeout = tunnel->timeout >= 0 ? tunnel->timeout : -1;
      struct proxy_tunnel_conn *client = tunnel->client, *origin = tunnel->origin;
      apr_size_t read_buf_size = ap_get_read_buf_size(r);
      const char *scheme = tunnel->scheme;
      apr_status_t rv;
  
      ap_log_rerror(APLOG_MARK, APLOG_TRACE1, 0, r, APLOGNO(10212)
                    "proxy: %s: tunnel running (timeout %" APR_TIME_T_FMT "."
                                                       "%" APR_TIME_T_FMT ")",
                    scheme, timeout > 0 ? apr_time_sec(timeout) : timeout,
                            timeout > 0 ? timeout % APR_USEC_PER_SEC : 0);
  
      client->pfd->reqevents = 0;
      origin->pfd->reqevents = 0;
      add_pollset(pollset, client->pfd, APR_POLLIN);
      add_pollset(pollset, origin->pfd, APR_POLLIN);
  
      /* Loop until both directions of the connection are closed,
       * or a failure occurs.
       */
      do {
          struct proxy_tunnel_conn *in, *out;
          const apr_pollfd_t *results;
          apr_int32_t nresults, i;
  
          ap_log_rerror(APLOG_MARK, APLOG_TRACE8, 0, r,
                        "proxy: %s: polling client=%hx, origin=%hx",
                        scheme, client->pfd->reqevents, origin->pfd->reqevents);
          do {
              rv = apr_pollset_poll(pollset, timeout, &nresults, &results);
          } while (APR_STATUS_IS_EINTR(rv));
  
          if (rv != APR_SUCCESS) {
              if (APR_STATUS_IS_TIMEUP(rv)) {
                  ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r, APLOGNO(10213)
                                "proxy: %s: polling timeout", scheme);
                  rc = HTTP_GATEWAY_TIME_OUT;
              }
              else {
                  ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(10214)
                                "proxy: %s: polling failed", scheme);
                  rc = HTTP_INTERNAL_SERVER_ERROR;
              }
              goto cleanup;
          }
  
          ap_log_rerror(APLOG_MARK, APLOG_TRACE8, 0, r, APLOGNO(10215)
                        "proxy: %s: woken up, %i result(s)", scheme, nresults);
  
          for (i = 0; i < nresults; i++) {
              const apr_pollfd_t *cur = &results[i];
              int revents = cur->rtnevents;
  
              /* sanity check */
              if (cur->desc.s != client->pfd->desc.s
                      && cur->desc.s != origin->pfd->desc.s) {
                  ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10222)
                                "proxy: %s: unknown socket in pollset", scheme);
                  rc = HTTP_INTERNAL_SERVER_ERROR;
                  goto cleanup;
              }
  
              in = cur->client_data;
              if (revents & APR_POLLOUT) {
                  in = in->other;
              }
              else if (!(revents & (APR_POLLIN | APR_POLLHUP))) {
                  /* this catches POLLERR/POLLNVAL etc.. */
                  ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10220)
                                "proxy: %s: polling events error (%x)",
                                scheme, revents);
                  rc = HTTP_INTERNAL_SERVER_ERROR;
                  goto cleanup;
              }
              out = in->other;
  
              ap_log_rerror(APLOG_MARK, APLOG_TRACE8, 0, r,
                            "proxy: %s: #%i: %s/%hx => %s/%hx: %x",
                            scheme, i, in->name, in->pfd->reqevents,
                            out->name, out->pfd->reqevents, revents);
  
              if (in->readable && (in->drain || !(revents & APR_POLLOUT))) {
                  int sent = 0;
  
                  ap_log_rerror(APLOG_MARK, APLOG_TRACE8, 0, r,
                                "proxy: %s: %s is %s", scheme, in->name,
                                (revents & APR_POLLOUT) ? "draining"
                                                        : "readable");
  
                  rv = ap_proxy_transfer_between_connections(r,
                                                 in->c, out->c,
                                                 in->bb, out->bb,
                                                 in->name, &sent,
                                                 read_buf_size,
                                                 AP_PROXY_TRANSFER_SHOULD_YIELD);
                  if (sent && out == client) {
                      tunnel->replied = 1;
                  }
                  if (rv != APR_SUCCESS) {
                      if (APR_STATUS_IS_INCOMPLETE(rv)) {
                          /* Pause POLLIN while waiting for POLLOUT on the other
                           * side, hence avoid filling the output filters even
                           * more and hence blocking there.
                           */
                          ap_log_rerror(APLOG_MARK, APLOG_TRACE8, 0, r,
                                        "proxy: %s: %s wait writable",
                                        scheme, out->name);
                          revents &= ~APR_POLLOUT;
                          in->drain = 1;
                      }
                      else if (APR_STATUS_IS_EOF(rv)) {
                          /* Stop POLLIN and wait for POLLOUT (flush) on the
                           * other side to shut it down.
                           */
                          ap_log_rerror(APLOG_MARK, APLOG_TRACE8, 0, r,
                                        "proxy: %s: %s read shutdown",
                                        scheme, in->name);
                          in->readable = in->drain = 0;
                      }
                      else {
                          /* Real failure, bail out */
                          rc = HTTP_INTERNAL_SERVER_ERROR;
                          goto cleanup;
                      }
                      del_pollset(pollset, in->pfd, APR_POLLIN);
                      sent = 1;
                  }
                  else {
                      in->drain = 0;
                  }
  
                  if (sent) {
                      add_pollset(pollset, out->pfd, APR_POLLOUT);
                  }
              }
  
              if (revents & APR_POLLOUT) {
                  ap_log_rerror(APLOG_MARK, APLOG_TRACE8, 0, r,
                                "proxy: %s: %s is writable",
                                scheme, out->name);
  
                  rv = ap_filter_output_pending(out->c);
                  if (rv == DECLINED) {
                      /* No more pending data. If the 'in' side is not readable
                       * anymore it's time to shutdown for write (this direction
                       * is over). Otherwise draining (if any) is done, back to
                       * normal business.
                       */
                      if (!in->readable) {
                          ap_log_rerror(APLOG_MARK, APLOG_TRACE8, 0, r,
                                        "proxy: %s: %s write shutdown",
                                        scheme, out->name);
                          del_pollset(pollset, out->pfd, APR_POLLOUT);
                          apr_socket_shutdown(out->pfd->desc.s, 1);
                      }
                      else {
                          add_pollset(pollset, in->pfd, APR_POLLIN);
                          if (!in->drain) {
                              del_pollset(pollset, out->pfd, APR_POLLOUT);
                          }
                      }
                  }
                  else if (rv != OK) {
                      /* Real failure, bail out */
                      ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10221)
                                    "proxy: %s: %s flushing failed (%i)",
                                    scheme, out->name, rv);
                      rc = HTTP_INTERNAL_SERVER_ERROR;
                      goto cleanup;
                  }
              }
          }
      } while (client->pfd->reqevents || origin->pfd->reqevents);
  
      ap_log_rerror(APLOG_MARK, APLOG_TRACE1, 0, r, APLOGNO(10223)
                    "proxy: %s: tunnel finished", scheme);
  
  cleanup:
      del_pollset(pollset, client->pfd, ~0);
      del_pollset(pollset, origin->pfd, ~0);
      return rc;
  }
  
  PROXY_DECLARE (const char *) ap_proxy_show_hcmethod(hcmethod_t method)
  {
      proxy_hcmethods_t *m = proxy_hcmethods;
      for (; m->name; m++) {
          if (m->method == method) {
              return m->name;
          }
      }
      return "???";
  }
  
  void proxy_util_register_hooks(apr_pool_t *p)
  {
      APR_REGISTER_OPTIONAL_FN(ap_proxy_retry_worker);
      APR_REGISTER_OPTIONAL_FN(ap_proxy_clear_connection);
      APR_REGISTER_OPTIONAL_FN(proxy_balancer_get_best_worker);
  }
  