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.
   */
  
  #include "apr_strings.h"
  #include "apr_thread_proc.h"    /* for RLIMIT stuff */
  
  #define APR_WANT_STRFUNC
  #include "apr_want.h"
  
  #include "httpd.h"
  #include "http_config.h"
  #include "http_connection.h"
  #include "http_core.h"
  #include "http_protocol.h"   /* For index_of_response().  Grump. */
  #include "http_request.h"
  
  #include "util_filter.h"
  #include "util_ebcdic.h"
  #include "ap_mpm.h"
  #include "scoreboard.h"
  
  #include "mod_core.h"
  
  /* Handles for core filters */
  AP_DECLARE_DATA ap_filter_rec_t *ap_http_input_filter_handle;
  AP_DECLARE_DATA ap_filter_rec_t *ap_http_header_filter_handle;
  AP_DECLARE_DATA ap_filter_rec_t *ap_chunk_filter_handle;
  AP_DECLARE_DATA ap_filter_rec_t *ap_http_outerror_filter_handle;
  AP_DECLARE_DATA ap_filter_rec_t *ap_byterange_filter_handle;
  
  AP_DECLARE_DATA const char *ap_multipart_boundary;
  
  /* If we are using an MPM That Supports Async Connections,
   * use a different processing function
   */
  static int async_mpm = 0;
  
  static const char *set_keep_alive_timeout(cmd_parms *cmd, void *dummy,
                                            const char *arg)
  {
      apr_interval_time_t timeout;
      const char *err = ap_check_cmd_context(cmd, NOT_IN_DIR_CONTEXT);
      if (err != NULL) {
          return err;
      }
  
      /* Stolen from mod_proxy.c */
      if (ap_timeout_parameter_parse(arg, &timeout, "s") != APR_SUCCESS)
          return "KeepAliveTimeout has wrong format";
      cmd->server->keep_alive_timeout = timeout;
  
      /* We don't want to take into account whether or not KeepAliveTimeout is
       * set for the main server, because if no http_module directive is used
       * for a vhost, it will inherit the http_srv_cfg from the main server.
       * However keep_alive_timeout_set helps determine whether the vhost should
       * use its own configured timeout or the one from the vhost declared first
       * on the same IP:port (ie. c->base_server, and the legacy behaviour).
       */
      if (cmd->server->is_virtual) {
          cmd->server->keep_alive_timeout_set = 1;
      }
      return NULL;
  }
  
  static const char *set_keep_alive(cmd_parms *cmd, void *dummy,
                                    int arg)
  {
      const char *err = ap_check_cmd_context(cmd, NOT_IN_DIR_CONTEXT);
      if (err != NULL) {
          return err;
      }
  
      cmd->server->keep_alive = arg;
      return NULL;
  }
  
  static const char *set_keep_alive_max(cmd_parms *cmd, void *dummy,
                                        const char *arg)
  {
      const char *err = ap_check_cmd_context(cmd, NOT_IN_DIR_CONTEXT);
      if (err != NULL) {
          return err;
      }
  
      cmd->server->keep_alive_max = atoi(arg);
      return NULL;
  }
  
  static const command_rec http_cmds[] = {
      AP_INIT_TAKE1("KeepAliveTimeout", set_keep_alive_timeout, NULL, RSRC_CONF,
                    "Keep-Alive timeout duration (sec)"),
      AP_INIT_TAKE1("MaxKeepAliveRequests", set_keep_alive_max, NULL, RSRC_CONF,
                    "Maximum number of Keep-Alive requests per connection, "
                    "or 0 for infinite"),
      AP_INIT_FLAG("KeepAlive", set_keep_alive, NULL, RSRC_CONF,
                    "Whether persistent connections should be On or Off"),
      { NULL }
  };
  
  static const char *http_scheme(const request_rec *r)
  {
      /*
       * The http module shouldn't return anything other than
       * "http" (the default) or "https".
       */
      if (r->server->server_scheme &&
          (strcmp(r->server->server_scheme, "https") == 0))
          return "https";
  
      return "http";
  }
  
  static apr_port_t http_port(const request_rec *r)
  {
      if (r->server->server_scheme &&
          (strcmp(r->server->server_scheme, "https") == 0))
          return DEFAULT_HTTPS_PORT;
  
      return DEFAULT_HTTP_PORT;
  }
  
  static int ap_process_http_async_connection(conn_rec *c)
  {
      request_rec *r = NULL;
      conn_state_t *cs = c->cs;
  
      AP_DEBUG_ASSERT(cs != NULL);
      AP_DEBUG_ASSERT(cs->state == CONN_STATE_READ_REQUEST_LINE);
  
      while (cs->state == CONN_STATE_READ_REQUEST_LINE) {
          ap_update_child_status_from_conn(c->sbh, SERVER_BUSY_READ, c);
  
          if ((r = ap_read_request(c))) {
  
              c->keepalive = AP_CONN_UNKNOWN;
              /* process the request if it was read without error */
  
              if (r->status == HTTP_OK) {
                  cs->state = CONN_STATE_HANDLER;
                  ap_update_child_status(c->sbh, SERVER_BUSY_WRITE, r);
                  ap_process_async_request(r);
                  /* After the call to ap_process_request, the
                   * request pool may have been deleted.  We set
                   * r=NULL here to ensure that any dereference
                   * of r that might be added later in this function
                   * will result in a segfault immediately instead
                   * of nondeterministic failures later.
                   */
                  r = NULL;
              }
  
              if (cs->state != CONN_STATE_WRITE_COMPLETION &&
                  cs->state != CONN_STATE_SUSPENDED) {
                  /* Something went wrong; close the connection */
                  cs->state = CONN_STATE_LINGER;
              }
          }
          else {   /* ap_read_request failed - client may have closed */
              cs->state = CONN_STATE_LINGER;
          }
      }
  
      return OK;
  }
  
  static int ap_process_http_sync_connection(conn_rec *c)
  {
      request_rec *r;
      conn_state_t *cs = c->cs;
      apr_socket_t *csd = NULL;
      int mpm_state = 0;
  
      /*
       * Read and process each request found on our connection
       * until no requests are left or we decide to close.
       */
  
      ap_update_child_status_from_conn(c->sbh, SERVER_BUSY_READ, c);
      while ((r = ap_read_request(c)) != NULL) {
          apr_interval_time_t keep_alive_timeout = r->server->keep_alive_timeout;
  
          /* To preserve legacy behaviour, use the keepalive timeout from the
           * base server (first on this IP:port) when none is explicitly
           * configured on this server.
           */
          if (!r->server->keep_alive_timeout_set) {
              keep_alive_timeout = c->base_server->keep_alive_timeout;
          }
  
          c->keepalive = AP_CONN_UNKNOWN;
          /* process the request if it was read without error */
  
          if (r->status == HTTP_OK) {
              if (cs)
                  cs->state = CONN_STATE_HANDLER;
              ap_update_child_status(c->sbh, SERVER_BUSY_WRITE, r);
              ap_process_request(r);
              /* After the call to ap_process_request, the
               * request pool will have been deleted.  We set
               * r=NULL here to ensure that any dereference
               * of r that might be added later in this function
               * will result in a segfault immediately instead
               * of nondeterministic failures later.
               */
              r = NULL;
          }
  
          if (c->keepalive != AP_CONN_KEEPALIVE || c->aborted)
              break;
  
          ap_update_child_status(c->sbh, SERVER_BUSY_KEEPALIVE, NULL);
  
          if (ap_mpm_query(AP_MPMQ_MPM_STATE, &mpm_state)) {
              break;
          }
  
          if (mpm_state == AP_MPMQ_STOPPING) {
            break;
          }
  
          if (!csd) {
              csd = ap_get_conn_socket(c);
          }
          apr_socket_opt_set(csd, APR_INCOMPLETE_READ, 1);
          apr_socket_timeout_set(csd, keep_alive_timeout);
          /* Go straight to select() to wait for the next request */
      }
  
      return OK;
  }
  
  static int ap_process_http_connection(conn_rec *c)
  {
      if (async_mpm && !c->clogging_input_filters) {
          return ap_process_http_async_connection(c);
      }
      else {
          return ap_process_http_sync_connection(c);
      }
  }
  
  static int http_create_request(request_rec *r)
  {
      if (!r->main && !r->prev) {
          ap_add_output_filter_handle(ap_byterange_filter_handle,
                                      NULL, r, r->connection);
          ap_add_output_filter_handle(ap_content_length_filter_handle,
                                      NULL, r, r->connection);
          ap_add_output_filter_handle(ap_http_header_filter_handle,
                                      NULL, r, r->connection);
          ap_add_output_filter_handle(ap_http_outerror_filter_handle,
                                      NULL, r, r->connection);
      }
  
      return OK;
  }
  
  static int http_send_options(request_rec *r)
  {
      if ((r->method_number == M_OPTIONS) && r->uri && (r->uri[0] == '*') &&
           (r->uri[1] == '\0')) {
          return DONE;           /* Send HTTP pong, without Allow header */
      }
      return DECLINED;
  }
  
  static int http_post_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s)
  {
      apr_uint64_t val;
      if (ap_mpm_query(AP_MPMQ_IS_ASYNC, &async_mpm) != APR_SUCCESS) {
          async_mpm = 0;
      }
      ap_random_insecure_bytes(&val, sizeof(val));
      ap_multipart_boundary = apr_psprintf(p, "%0" APR_UINT64_T_HEX_FMT, val);
  
      return OK;
  }
  
  static void register_hooks(apr_pool_t *p)
  {
      ap_hook_post_config(http_post_config, NULL, NULL, APR_HOOK_MIDDLE);
      ap_hook_process_connection(ap_process_http_connection, NULL, NULL,
                                 APR_HOOK_REALLY_LAST);
      ap_hook_map_to_storage(ap_send_http_trace,NULL,NULL,APR_HOOK_MIDDLE);
      ap_hook_map_to_storage(http_send_options,NULL,NULL,APR_HOOK_MIDDLE);
      ap_hook_http_scheme(http_scheme,NULL,NULL,APR_HOOK_REALLY_LAST);
      ap_hook_default_port(http_port,NULL,NULL,APR_HOOK_REALLY_LAST);
      ap_hook_create_request(http_create_request, NULL, NULL, APR_HOOK_REALLY_LAST);
      ap_http_input_filter_handle =
          ap_register_input_filter("HTTP_IN", ap_http_filter,
                                   NULL, AP_FTYPE_PROTOCOL);
      ap_http_header_filter_handle =
          ap_register_output_filter("HTTP_HEADER", ap_http_header_filter,
                                    NULL, AP_FTYPE_PROTOCOL);
      ap_chunk_filter_handle =
          ap_register_output_filter("CHUNK", ap_http_chunk_filter,
                                    NULL, AP_FTYPE_TRANSCODE);
      ap_http_outerror_filter_handle =
          ap_register_output_filter("HTTP_OUTERROR", ap_http_outerror_filter,
                                    NULL, AP_FTYPE_PROTOCOL);
      ap_byterange_filter_handle =
          ap_register_output_filter("BYTERANGE", ap_byterange_filter,
                                    NULL, AP_FTYPE_PROTOCOL);
      ap_method_registry_init(p);
  }
  
  AP_DECLARE_MODULE(http) = {
      STANDARD20_MODULE_STUFF,
      NULL,              /* create per-directory config structure */
      NULL,              /* merge per-directory config structures */
      NULL,              /* create per-server config structure */
      NULL,              /* merge per-server config structures */
      http_cmds,         /* command apr_table_t */
      register_hooks     /* register hooks */
  };
  