text: /***************************************************************************
   *                                  _   _ ____  _
   *  Project                     ___| | | |  _ \| |
   *                             / __| | | | |_) | |
   *                            | (__| |_| |  _ <| |___
   *                             \___|\___/|_| \_\_____|
   *
   * Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
   *
   * This software is licensed as described in the file COPYING, which
   * you should have received as part of this distribution. The terms
   * are also available at http://curl.haxx.se/docs/copyright.html.
   *
   * You may opt to use, copy, modify, merge, publish, distribute and/or sell
   * copies of the Software, and permit persons to whom the Software is
   * furnished to do so, under the terms of the COPYING file.
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
   * KIND, either express or implied.
   *
   ***************************************************************************/
  
  #include "curl_setup.h"
  
  #ifdef HAVE_NETINET_IN_H
  #include <netinet/in.h>
  #endif
  #ifdef HAVE_NETDB_H
  #include <netdb.h>
  #endif
  #ifdef HAVE_ARPA_INET_H
  #include <arpa/inet.h>
  #endif
  #ifdef __VMS
  #include <in.h>
  #include <inet.h>
  #endif
  
  #if defined(USE_THREADS_POSIX)
  #  ifdef HAVE_PTHREAD_H
  #    include <pthread.h>
  #  endif
  #elif defined(USE_THREADS_WIN32)
  #  ifdef HAVE_PROCESS_H
  #    include <process.h>
  #  endif
  #endif
  
  #if (defined(NETWARE) && defined(__NOVELL_LIBC__))
  #undef in_addr_t
  #define in_addr_t unsigned long
  #endif
  
  #ifdef HAVE_GETADDRINFO
  #  define RESOLVER_ENOMEM  EAI_MEMORY
  #else
  #  define RESOLVER_ENOMEM  ENOMEM
  #endif
  
  #include "urldata.h"
  #include "sendf.h"
  #include "hostip.h"
  #include "hash.h"
  #include "share.h"
  #include "strerror.h"
  #include "url.h"
  #include "multiif.h"
  #include "inet_pton.h"
  #include "inet_ntop.h"
  #include "curl_threads.h"
  
  #define _MPRINTF_REPLACE /* use our functions only */
  #include <curl/mprintf.h>
  
  #include "curl_memory.h"
  /* The last #include file should be: */
  #include "memdebug.h"
  
  /***********************************************************************
   * Only for threaded name resolves builds
   **********************************************************************/
  #ifdef CURLRES_THREADED
  
  /*
   * Curl_resolver_global_init()
   * Called from curl_global_init() to initialize global resolver environment.
   * Does nothing here.
   */
  int Curl_resolver_global_init(void)
  {
    return CURLE_OK;
  }
  
  /*
   * Curl_resolver_global_cleanup()
   * Called from curl_global_cleanup() to destroy global resolver environment.
   * Does nothing here.
   */
  void Curl_resolver_global_cleanup(void)
  {
  }
  
  /*
   * Curl_resolver_init()
   * Called from curl_easy_init() -> Curl_open() to initialize resolver
   * URL-state specific environment ('resolver' member of the UrlState
   * structure).  Does nothing here.
   */
  CURLcode Curl_resolver_init(void **resolver)
  {
    (void)resolver;
    return CURLE_OK;
  }
  
  /*
   * Curl_resolver_cleanup()
   * Called from curl_easy_cleanup() -> Curl_close() to cleanup resolver
   * URL-state specific environment ('resolver' member of the UrlState
   * structure).  Does nothing here.
   */
  void Curl_resolver_cleanup(void *resolver)
  {
    (void)resolver;
  }
  
  /*
   * Curl_resolver_duphandle()
   * Called from curl_easy_duphandle() to duplicate resolver URL state-specific
   * environment ('resolver' member of the UrlState structure).  Does nothing
   * here.
   */
  int Curl_resolver_duphandle(void **to, void *from)
  {
    (void)to;
    (void)from;
    return CURLE_OK;
  }
  
  static void destroy_async_data(struct Curl_async *);
  
  /*
   * Cancel all possibly still on-going resolves for this connection.
   */
  void Curl_resolver_cancel(struct connectdata *conn)
  {
    destroy_async_data(&conn->async);
  }
  
  /* This function is used to init a threaded resolve */
  static bool init_resolve_thread(struct connectdata *conn,
                                  const char *hostname, int port,
                                  const struct addrinfo *hints);
  
  
  /* Data for synchronization between resolver thread and its parent */
  struct thread_sync_data {
    curl_mutex_t * mtx;
    int done;
  
    char * hostname;        /* hostname to resolve, Curl_async.hostname
                               duplicate */
    int port;
    int sock_error;
    Curl_addrinfo *res;
  #ifdef HAVE_GETADDRINFO
    struct addrinfo hints;
  #endif
  };
  
  struct thread_data {
    curl_thread_t thread_hnd;
    unsigned int poll_interval;
    long interval_end;
    struct thread_sync_data tsd;
  };
  
  static struct thread_sync_data *conn_thread_sync_data(struct connectdata *conn)
  {
    return &(((struct thread_data *)conn->async.os_specific)->tsd);
  }
  
  #define CONN_THREAD_SYNC_DATA(conn) &(((conn)->async.os_specific)->tsd);
  
  /* Destroy resolver thread synchronization data */
  static
  void destroy_thread_sync_data(struct thread_sync_data * tsd)
  {
    if(tsd->mtx) {
      Curl_mutex_destroy(tsd->mtx);
      free(tsd->mtx);
    }
  
    if(tsd->hostname)
      free(tsd->hostname);
  
    if(tsd->res)
      Curl_freeaddrinfo(tsd->res);
  
    memset(tsd,0,sizeof(*tsd));
  }
  
  /* Initialize resolver thread synchronization data */
  static
  int init_thread_sync_data(struct thread_sync_data * tsd,
                             const char * hostname,
                             int port,
                             const struct addrinfo *hints)
  {
    memset(tsd, 0, sizeof(*tsd));
  
    tsd->port = port;
  #ifdef CURLRES_IPV6
    DEBUGASSERT(hints);
    tsd->hints = *hints;
  #else
    (void) hints;
  #endif
  
    tsd->mtx = malloc(sizeof(curl_mutex_t));
    if(tsd->mtx == NULL)
      goto err_exit;
  
    Curl_mutex_init(tsd->mtx);
  
    tsd->sock_error = CURL_ASYNC_SUCCESS;
  
    /* Copying hostname string because original can be destroyed by parent
     * thread during gethostbyname execution.
     */
    tsd->hostname = strdup(hostname);
    if(!tsd->hostname)
      goto err_exit;
  
    return 1;
  
   err_exit:
    /* Memory allocation failed */
    destroy_thread_sync_data(tsd);
    return 0;
  }
  
  static int getaddrinfo_complete(struct connectdata *conn)
  {
    struct thread_sync_data *tsd = conn_thread_sync_data(conn);
    int rc;
  
    rc = Curl_addrinfo_callback(conn, tsd->sock_error, tsd->res);
    /* The tsd->res structure has been copied to async.dns and perhaps the DNS
       cache.  Set our copy to NULL so destroy_thread_sync_data doesn't free it.
    */
    tsd->res = NULL;
  
    return rc;
  }
  
  
  #ifdef HAVE_GETADDRINFO
  
  /*
   * getaddrinfo_thread() resolves a name and then exits.
   *
   * For builds without ARES, but with ENABLE_IPV6, create a resolver thread
   * and wait on it.
   */
  static unsigned int CURL_STDCALL getaddrinfo_thread (void *arg)
  {
    struct thread_sync_data *tsd = (struct thread_sync_data*)arg;
    char   service [NI_MAXSERV];
    int rc;
  
    snprintf(service, sizeof(service), "%d", tsd->port);
  
    rc = Curl_getaddrinfo_ex(tsd->hostname, service, &tsd->hints, &tsd->res);
  
    if(rc != 0) {
      tsd->sock_error = SOCKERRNO?SOCKERRNO:rc;
      if(tsd->sock_error == 0)
        tsd->sock_error = RESOLVER_ENOMEM;
    }
  
    Curl_mutex_acquire(tsd->mtx);
    tsd->done = 1;
    Curl_mutex_release(tsd->mtx);
  
    return 0;
  }
  
  #else /* HAVE_GETADDRINFO */
  
  /*
   * gethostbyname_thread() resolves a name and then exits.
   */
  static unsigned int CURL_STDCALL gethostbyname_thread (void *arg)
  {
    struct thread_sync_data *tsd = (struct thread_sync_data *)arg;
  
    tsd->res = Curl_ipv4_resolve_r(tsd->hostname, tsd->port);
  
    if(!tsd->res) {
      tsd->sock_error = SOCKERRNO;
      if(tsd->sock_error == 0)
        tsd->sock_error = RESOLVER_ENOMEM;
    }
  
    Curl_mutex_acquire(tsd->mtx);
    tsd->done = 1;
    Curl_mutex_release(tsd->mtx);
  
    return 0;
  }
  
  #endif /* HAVE_GETADDRINFO */
  
  /*
   * destroy_async_data() cleans up async resolver data and thread handle.
   */
  static void destroy_async_data (struct Curl_async *async)
  {
    if(async->hostname)
      free(async->hostname);
  
    if(async->os_specific) {
      struct thread_data *td = (struct thread_data*) async->os_specific;
  
      if(td->thread_hnd != curl_thread_t_null)
        Curl_thread_join(&td->thread_hnd);
  
      destroy_thread_sync_data(&td->tsd);
  
      free(async->os_specific);
    }
    async->hostname = NULL;
    async->os_specific = NULL;
  }
  
  /*
   * init_resolve_thread() starts a new thread that performs the actual
   * resolve. This function returns before the resolve is done.
   *
   * Returns FALSE in case of failure, otherwise TRUE.
   */
  static bool init_resolve_thread (struct connectdata *conn,
                                   const char *hostname, int port,
                                   const struct addrinfo *hints)
  {
    struct thread_data *td = calloc(1, sizeof(struct thread_data));
    int err = RESOLVER_ENOMEM;
  
    conn->async.os_specific = (void*) td;
    if(!td)
      goto err_exit;
  
    conn->async.port = port;
    conn->async.done = FALSE;
    conn->async.status = 0;
    conn->async.dns = NULL;
    td->thread_hnd = curl_thread_t_null;
  
    if(!init_thread_sync_data(&td->tsd, hostname, port, hints))
      goto err_exit;
  
    Curl_safefree(conn->async.hostname);
    conn->async.hostname = strdup(hostname);
    if(!conn->async.hostname)
      goto err_exit;
  
  #ifdef HAVE_GETADDRINFO
    td->thread_hnd = Curl_thread_create(getaddrinfo_thread, &td->tsd);
  #else
    td->thread_hnd = Curl_thread_create(gethostbyname_thread, &td->tsd);
  #endif
  
    if(!td->thread_hnd) {
  #ifndef _WIN32_WCE
      err = errno;
  #endif
      goto err_exit;
    }
  
    return TRUE;
  
   err_exit:
    destroy_async_data(&conn->async);
  
    SET_ERRNO(err);
  
    return FALSE;
  }
  
  /*
   * resolver_error() calls failf() with the appropriate message after a resolve
   * error
   */
  
  static CURLcode resolver_error(struct connectdata *conn)
  {
    const char *host_or_proxy;
    CURLcode rc;
    if(conn->bits.httpproxy) {
      host_or_proxy = "proxy";
      rc = CURLE_COULDNT_RESOLVE_PROXY;
    }
    else {
      host_or_proxy = "host";
      rc = CURLE_COULDNT_RESOLVE_HOST;
    }
  
    failf(conn->data, "Could not resolve %s: %s", host_or_proxy,
          conn->async.hostname);
    return rc;
  }
  
  /*
   * Curl_resolver_wait_resolv()
   *
   * waits for a resolve to finish. This function should be avoided since using
   * this risk getting the multi interface to "hang".
   *
   * If 'entry' is non-NULL, make it point to the resolved dns entry
   *
   * This is the version for resolves-in-a-thread.
   */
  CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
                                     struct Curl_dns_entry **entry)
  {
    struct thread_data   *td = (struct thread_data*) conn->async.os_specific;
    CURLcode rc = CURLE_OK;
  
    DEBUGASSERT(conn && td);
  
    /* wait for the thread to resolve the name */
    if(Curl_thread_join(&td->thread_hnd))
      rc = getaddrinfo_complete(conn);
    else
      DEBUGASSERT(0);
  
    conn->async.done = TRUE;
  
    if(entry)
      *entry = conn->async.dns;
  
    if(!conn->async.dns)
      /* a name was not resolved, report error */
      rc = resolver_error(conn);
  
    destroy_async_data(&conn->async);
  
    if(!conn->async.dns)
      conn->bits.close = TRUE;
  
    return (rc);
  }
  
  /*
   * Curl_resolver_is_resolved() is called repeatedly to check if a previous
   * name resolve request has completed. It should also make sure to time-out if
   * the operation seems to take too long.
   */
  CURLcode Curl_resolver_is_resolved(struct connectdata *conn,
                                     struct Curl_dns_entry **entry)
  {
    struct SessionHandle *data = conn->data;
    struct thread_data   *td = (struct thread_data*) conn->async.os_specific;
    int done = 0;
  
    *entry = NULL;
  
    if(!td) {
      DEBUGASSERT(td);
      return CURLE_COULDNT_RESOLVE_HOST;
    }
  
    Curl_mutex_acquire(td->tsd.mtx);
    done = td->tsd.done;
    Curl_mutex_release(td->tsd.mtx);
  
    if(done) {
      getaddrinfo_complete(conn);
  
      if(!conn->async.dns) {
        CURLcode rc = resolver_error(conn);
        destroy_async_data(&conn->async);
        return rc;
      }
      destroy_async_data(&conn->async);
      *entry = conn->async.dns;
    }
    else {
      /* poll for name lookup done with exponential backoff up to 250ms */
      long elapsed = Curl_tvdiff(Curl_tvnow(), data->progress.t_startsingle);
      if(elapsed < 0)
        elapsed = 0;
  
      if(td->poll_interval == 0)
        /* Start at 1ms poll interval */
        td->poll_interval = 1;
      else if(elapsed >= td->interval_end)
        /* Back-off exponentially if last interval expired  */
        td->poll_interval *= 2;
  
      if(td->poll_interval > 250)
        td->poll_interval = 250;
  
      td->interval_end = elapsed + td->poll_interval;
      Curl_expire(conn->data, td->poll_interval);
    }
  
    return CURLE_OK;
  }
  
  int Curl_resolver_getsock(struct connectdata *conn,
                            curl_socket_t *socks,
                            int numsocks)
  {
    (void)conn;
    (void)socks;
    (void)numsocks;
    return 0;
  }
  
  #ifndef HAVE_GETADDRINFO
  /*
   * Curl_getaddrinfo() - for platforms without getaddrinfo
   */
  Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
                                           const char *hostname,
                                           int port,
                                           int *waitp)
  {
    struct in_addr in;
  
    *waitp = 0; /* default to synchronous response */
  
    if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
      /* This is a dotted IP address 123.123.123.123-style */
      return Curl_ip2addr(AF_INET, &in, hostname, port);
  
    /* fire up a new resolver thread! */
    if(init_resolve_thread(conn, hostname, port, NULL)) {
      *waitp = 1; /* expect asynchronous response */
      return NULL;
    }
  
    /* fall-back to blocking version */
    return Curl_ipv4_resolve_r(hostname, port);
  }
  
  #else /* !HAVE_GETADDRINFO */
  
  /*
   * Curl_resolver_getaddrinfo() - for getaddrinfo
   */
  Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
                                           const char *hostname,
                                           int port,
                                           int *waitp)
  {
    struct addrinfo hints;
    struct in_addr in;
    Curl_addrinfo *res;
    int error;
    char sbuf[NI_MAXSERV];
    int pf = PF_INET;
  #ifdef CURLRES_IPV6
    struct in6_addr in6;
  #endif /* CURLRES_IPV6 */
  
    *waitp = 0; /* default to synchronous response */
  
    /* First check if this is an IPv4 address string */
    if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
      /* This is a dotted IP address 123.123.123.123-style */
      return Curl_ip2addr(AF_INET, &in, hostname, port);
  
  #ifdef CURLRES_IPV6
    /* check if this is an IPv6 address string */
    if(Curl_inet_pton (AF_INET6, hostname, &in6) > 0)
      /* This is an IPv6 address literal */
      return Curl_ip2addr(AF_INET6, &in6, hostname, port);
  
    /*
     * Check if a limited name resolve has been requested.
     */
    switch(conn->ip_version) {
    case CURL_IPRESOLVE_V4:
      pf = PF_INET;
      break;
    case CURL_IPRESOLVE_V6:
      pf = PF_INET6;
      break;
    default:
      pf = PF_UNSPEC;
      break;
    }
  
    if((pf != PF_INET) && !Curl_ipv6works())
      /* the stack seems to be a non-ipv6 one */
      pf = PF_INET;
  
  #endif /* CURLRES_IPV6 */
  
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = pf;
    hints.ai_socktype = conn->socktype;
  
    snprintf(sbuf, sizeof(sbuf), "%d", port);
  
    /* fire up a new resolver thread! */
    if(init_resolve_thread(conn, hostname, port, &hints)) {
      *waitp = 1; /* expect asynchronous response */
      return NULL;
    }
  
    /* fall-back to blocking version */
    infof(conn->data, "init_resolve_thread() failed for %s; %s\n",
          hostname, Curl_strerror(conn, ERRNO));
  
    error = Curl_getaddrinfo_ex(hostname, sbuf, &hints, &res);
    if(error) {
      infof(conn->data, "getaddrinfo() failed for %s:%d; %s\n",
            hostname, port, Curl_strerror(conn, SOCKERRNO));
      return NULL;
    }
    return res;
  }
  
  #endif /* !HAVE_GETADDRINFO */
  
  CURLcode Curl_set_dns_servers(struct SessionHandle *data,
                                char *servers)
  {
    (void)data;
    (void)servers;
    return CURLE_NOT_BUILT_IN;
  
  }
  
  #endif /* CURLRES_THREADED */
  