url.c

      conn->data = data;
      conn->bits.tcpconnect[FIRSTSOCKET] = TRUE; /* we are "connected */

      Curl_conncache_add_conn(data->state.conn_cache, conn);

      /*
       * Setup whatever necessary for a resumed transfer
       */
      result = setup_range(data);
      if(result) {
        DEBUGASSERT(conn->handler->done);
        /* we ignore the return code for the protocol-specific DONE */
        (void)conn->handler->done(conn, result, FALSE);
        goto out;
      }

      Curl_setup_transfer(conn, -1, -1, FALSE, NULL, /* no download */
                          -1, NULL); /* no upload */
    }

    /* since we skip do_init() */
    Curl_init_do(data, conn);

    goto out;
  }
#endif

  /* Get a cloned copy of the SSL config situation stored in the
     connection struct. But to get this going nicely, we must first make
     sure that the strings in the master copy are pointing to the correct
     strings in the session handle strings array!

     Keep in mind that the pointers in the master copy are pointing to strings
     that will be freed as part of the SessionHandle struct, but all cloned
     copies will be separately allocated.
  */
  data->set.ssl.CApath = data->set.str[STRING_SSL_CAPATH];
  data->set.ssl.CAfile = data->set.str[STRING_SSL_CAFILE];
  data->set.ssl.CRLfile = data->set.str[STRING_SSL_CRLFILE];
  data->set.ssl.issuercert = data->set.str[STRING_SSL_ISSUERCERT];
  data->set.ssl.random_file = data->set.str[STRING_SSL_RANDOM_FILE];
  data->set.ssl.egdsocket = data->set.str[STRING_SSL_EGDSOCKET];
  data->set.ssl.cipher_list = data->set.str[STRING_SSL_CIPHER_LIST];
#ifdef USE_TLS_SRP
  data->set.ssl.username = data->set.str[STRING_TLSAUTH_USERNAME];
  data->set.ssl.password = data->set.str[STRING_TLSAUTH_PASSWORD];
#endif

  if(!Curl_clone_ssl_config(&data->set.ssl, &conn->ssl_config)) {
    result = CURLE_OUT_OF_MEMORY;
    goto out;
  }

  prune_dead_connections(data);

  /*************************************************************
   * Check the current list of connections to see if we can
   * re-use an already existing one or if we have to create a
   * new one.
   *************************************************************/

  /* reuse_fresh is TRUE if we are told to use a new connection by force, but
     we only acknowledge this option if this is not a re-used connection
     already (which happens due to follow-location or during a HTTP
     authentication phase). */
  if(data->set.reuse_fresh && !data->state.this_is_a_follow)
    reuse = FALSE;
  else
    reuse = ConnectionExists(data, conn, &conn_temp, &force_reuse, &waitpipe);

  /* If we found a reusable connection, we may still want to
     open a new connection if we are pipelining. */
  if(reuse && !force_reuse && IsPipeliningPossible(data, conn_temp)) {
    size_t pipelen = conn_temp->send_pipe->size + conn_temp->recv_pipe->size;
    if(pipelen > 0) {
      infof(data, "Found connection %ld, with requests in the pipe (%zu)\n",
            conn_temp->connection_id, pipelen);

      if(conn_temp->bundle->num_connections < max_host_connections &&
         data->state.conn_cache->num_connections < max_total_connections) {
        /* We want a new connection anyway */
        reuse = FALSE;

        infof(data, "We can reuse, but we want a new connection anyway\n");
      }
    }
  }

  if(reuse) {
    /*
     * We already have a connection for this, we got the former connection
     * in the conn_temp variable and thus we need to cleanup the one we
     * just allocated before we can move along and use the previously
     * existing one.
     */
    conn_temp->inuse = TRUE; /* mark this as being in use so that no other
                                handle in a multi stack may nick it */
    reuse_conn(conn, conn_temp);
    free(conn);          /* we don't need this anymore */
    conn = conn_temp;
    *in_connect = conn;

    infof(data, "Re-using existing connection! (#%ld) with %s %s\n",
          conn->connection_id,
          conn->bits.proxy?"proxy":"host",
          conn->proxy.name?conn->proxy.dispname:conn->host.dispname);
  }
  else {
    /* We have decided that we want a new connection. However, we may not
       be able to do that if we have reached the limit of how many
       connections we are allowed to open. */
    struct connectbundle *bundle = NULL;

    if(waitpipe)
      /* There is a connection that *might* become usable for pipelining
         "soon", and we wait for that */
      connections_available = FALSE;
    else
      bundle = Curl_conncache_find_bundle(conn, data->state.conn_cache);

    if(max_host_connections > 0 && bundle &&
       (bundle->num_connections >= max_host_connections)) {
      struct connectdata *conn_candidate;

      /* The bundle is full. Let's see if we can kill a connection. */
      conn_candidate = find_oldest_idle_connection_in_bundle(data, bundle);

      if(conn_candidate) {
        /* Set the connection's owner correctly, then kill it */
        conn_candidate->data = data;
        (void)Curl_disconnect(conn_candidate, /* dead_connection */ FALSE);
      }
      else {
        infof(data, "No more connections allowed to host: %d\n",
              max_host_connections);
        connections_available = FALSE;
      }
    }

    if(connections_available &&
       (max_total_connections > 0) &&
       (data->state.conn_cache->num_connections >= max_total_connections)) {
      struct connectdata *conn_candidate;

      /* The cache is full. Let's see if we can kill a connection. */
      conn_candidate = Curl_oldest_idle_connection(data);

      if(conn_candidate) {
        /* Set the connection's owner correctly, then kill it */
        conn_candidate->data = data;
        (void)Curl_disconnect(conn_candidate, /* dead_connection */ FALSE);
      }
      else {
        infof(data, "No connections available in cache\n");
        connections_available = FALSE;
      }
    }

    if(!connections_available) {
      infof(data, "No connections available.\n");

      conn_free(conn);
      *in_connect = NULL;

      result = CURLE_NO_CONNECTION_AVAILABLE;
      goto out;
    }
    else {
      /*
       * This is a brand new connection, so let's store it in the connection
       * cache of ours!
       */
      Curl_conncache_add_conn(data->state.conn_cache, conn);
    }

#if defined(USE_NTLM)
    /* If NTLM is requested in a part of this connection, make sure we don't
       assume the state is fine as this is a fresh connection and NTLM is
       connection based. */
    if((data->state.authhost.picked & (CURLAUTH_NTLM | CURLAUTH_NTLM_WB)) &&
       data->state.authhost.done) {
      infof(data, "NTLM picked AND auth done set, clear picked!\n");
      data->state.authhost.picked = CURLAUTH_NONE;
      data->state.authhost.done = FALSE;
    }

    if((data->state.authproxy.picked & (CURLAUTH_NTLM | CURLAUTH_NTLM_WB)) &&
       data->state.authproxy.done) {
      infof(data, "NTLM-proxy picked AND auth done set, clear picked!\n");
      data->state.authproxy.picked = CURLAUTH_NONE;
      data->state.authproxy.done = FALSE;
    }
#endif
  }

  /* Mark the connection as used */
  conn->inuse = TRUE;

  /* Setup and init stuff before DO starts, in preparing for the transfer. */
  Curl_init_do(data, conn);

  /*
   * Setup whatever necessary for a resumed transfer
   */
  result = setup_range(data);
  if(result)
    goto out;

  /* Continue connectdata initialization here. */

  /*
   * Inherit the proper values from the urldata struct AFTER we have arranged
   * the persistent connection stuff
   */
  conn->seek_func = data->set.seek_func;
  conn->seek_client = data->set.seek_client;

  /*************************************************************
   * Resolve the address of the server or proxy
   *************************************************************/
  result = resolve_server(data, conn, async);

  out:

  free(options);
  free(passwd);
  free(user);
  free(proxy);
  return result;
}

/* Curl_setup_conn() is called after the name resolve initiated in
 * create_conn() is all done.
 *
 * Curl_setup_conn() also handles reused connections
 *
 * conn->data MUST already have been setup fine (in create_conn)
 */

CURLcode Curl_setup_conn(struct connectdata *conn,
                         bool *protocol_done)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  Curl_pgrsTime(data, TIMER_NAMELOOKUP);

  if(conn->handler->flags & PROTOPT_NONETWORK) {
    /* nothing to setup when not using a network */
    *protocol_done = TRUE;
    return result;
  }
  *protocol_done = FALSE; /* default to not done */

  /* set proxy_connect_closed to false unconditionally already here since it
     is used strictly to provide extra information to a parent function in the
     case of proxy CONNECT failures and we must make sure we don't have it
     lingering set from a previous invoke */
  conn->bits.proxy_connect_closed = FALSE;

  /*
   * Set user-agent. Used for HTTP, but since we can attempt to tunnel
   * basically anything through a http proxy we can't limit this based on
   * protocol.
   */
  if(data->set.str[STRING_USERAGENT]) {
    Curl_safefree(conn->allocptr.uagent);
    conn->allocptr.uagent =
      aprintf("User-Agent: %s\r\n", data->set.str[STRING_USERAGENT]);
    if(!conn->allocptr.uagent)
      return CURLE_OUT_OF_MEMORY;
  }

  data->req.headerbytecount = 0;

#ifdef CURL_DO_LINEEND_CONV
  data->state.crlf_conversions = 0; /* reset CRLF conversion counter */
#endif /* CURL_DO_LINEEND_CONV */

  /* set start time here for timeout purposes in the connect procedure, it
     is later set again for the progress meter purpose */
  conn->now = Curl_tvnow();

  if(CURL_SOCKET_BAD == conn->sock[FIRSTSOCKET]) {
    conn->bits.tcpconnect[FIRSTSOCKET] = FALSE;
    result = Curl_connecthost(conn, conn->dns_entry);
    if(result)
      return result;
  }
  else {
    Curl_pgrsTime(data, TIMER_CONNECT);    /* we're connected already */
    Curl_pgrsTime(data, TIMER_APPCONNECT); /* we're connected already */
    conn->bits.tcpconnect[FIRSTSOCKET] = TRUE;
    *protocol_done = TRUE;
    Curl_updateconninfo(conn, conn->sock[FIRSTSOCKET]);
    Curl_verboseconnect(conn);
  }

  conn->now = Curl_tvnow(); /* time this *after* the connect is done, we
                               set this here perhaps a second time */

#ifdef __EMX__
  /*
   * This check is quite a hack. We're calling _fsetmode to fix the problem
   * with fwrite converting newline characters (you get mangled text files,
   * and corrupted binary files when you download to stdout and redirect it to
   * a file).
   */

  if((data->set.out)->_handle == NULL) {
    _fsetmode(stdout, "b");
  }
#endif

  return result;
}

CURLcode Curl_connect(struct SessionHandle *data,
                      struct connectdata **in_connect,
                      bool *asyncp,
                      bool *protocol_done)
{
  CURLcode result;

  *asyncp = FALSE; /* assume synchronous resolves by default */

  /* call the stuff that needs to be called */
  result = create_conn(data, in_connect, asyncp);

  if(!result) {
    /* no error */
    if((*in_connect)->send_pipe->size || (*in_connect)->recv_pipe->size)
      /* pipelining */
      *protocol_done = TRUE;
    else if(!*asyncp) {
      /* DNS resolution is done: that's either because this is a reused
         connection, in which case DNS was unnecessary, or because DNS
         really did finish already (synch resolver/fast async resolve) */
      result = Curl_setup_conn(*in_connect, protocol_done);
    }
  }

  if(result == CURLE_NO_CONNECTION_AVAILABLE) {
    *in_connect = NULL;
    return result;
  }

  if(result && *in_connect) {
    /* We're not allowed to return failure with memory left allocated
       in the connectdata struct, free those here */
    Curl_disconnect(*in_connect, FALSE); /* close the connection */
    *in_connect = NULL;           /* return a NULL */
  }

  return result;
}

/*
 * Curl_init_do() inits the readwrite session. This is inited each time (in
 * the DO function before the protocol-specific DO functions are invoked) for
 * a transfer, sometimes multiple times on the same SessionHandle. Make sure
 * nothing in here depends on stuff that are setup dynamically for the
 * transfer.
 *
 * Allow this function to get called with 'conn' set to NULL.
 */

CURLcode Curl_init_do(struct SessionHandle *data, struct connectdata *conn)
{
  struct SingleRequest *k = &data->req;

  if(conn)
    conn->bits.do_more = FALSE; /* by default there's no curl_do_more() to
                                 * use */

  data->state.done = FALSE; /* *_done() is not called yet */
  data->state.expect100header = FALSE;

  if(data->set.opt_no_body)
    /* in HTTP lingo, no body means using the HEAD request... */
    data->set.httpreq = HTTPREQ_HEAD;
  else if(HTTPREQ_HEAD == data->set.httpreq)
    /* ... but if unset there really is no perfect method that is the
       "opposite" of HEAD but in reality most people probably think GET
       then. The important thing is that we can't let it remain HEAD if the
       opt_no_body is set FALSE since then we'll behave wrong when getting
       HTTP. */
    data->set.httpreq = HTTPREQ_GET;

  k->start = Curl_tvnow(); /* start time */
  k->now = k->start;   /* current time is now */
  k->header = TRUE; /* assume header */

  k->bytecount = 0;

  k->buf = data->state.buffer;
  k->uploadbuf = data->state.uploadbuffer;
  k->hbufp = data->state.headerbuff;
  k->ignorebody=FALSE;

  Curl_speedinit(data);

  Curl_pgrsSetUploadCounter(data, 0);
  Curl_pgrsSetDownloadCounter(data, 0);

  return CURLE_OK;
}

/*
* get_protocol_family()
*
* This is used to return the protocol family for a given protocol.
*
* Parameters:
*
* protocol  [in]  - A single bit protocol identifier such as HTTP or HTTPS.
*
* Returns the family as a single bit protocol identifier.
*/

unsigned int get_protocol_family(unsigned int protocol)
{
  unsigned int family;

  switch(protocol) {
  case CURLPROTO_HTTP:
  case CURLPROTO_HTTPS:
    family = CURLPROTO_HTTP;
    break;

  case CURLPROTO_FTP:
  case CURLPROTO_FTPS:
    family = CURLPROTO_FTP;
    break;

  case CURLPROTO_SCP:
    family = CURLPROTO_SCP;
    break;

  case CURLPROTO_SFTP:
    family = CURLPROTO_SFTP;
    break;

  case CURLPROTO_TELNET:
    family = CURLPROTO_TELNET;
    break;

  case CURLPROTO_LDAP:
  case CURLPROTO_LDAPS:
    family = CURLPROTO_LDAP;
    break;

  case CURLPROTO_DICT:
    family = CURLPROTO_DICT;
    break;

  case CURLPROTO_FILE:
    family = CURLPROTO_FILE;
    break;

  case CURLPROTO_TFTP:
    family = CURLPROTO_TFTP;
    break;

  case CURLPROTO_IMAP:
  case CURLPROTO_IMAPS:
    family = CURLPROTO_IMAP;
    break;

  case CURLPROTO_POP3:
  case CURLPROTO_POP3S:
    family = CURLPROTO_POP3;
    break;

  case CURLPROTO_SMTP:
  case CURLPROTO_SMTPS:
      family = CURLPROTO_SMTP;
      break;

  case CURLPROTO_RTSP:
    family = CURLPROTO_RTSP;
    break;

  case CURLPROTO_RTMP:
  case CURLPROTO_RTMPS:
    family = CURLPROTO_RTMP;
    break;

  case CURLPROTO_RTMPT:
  case CURLPROTO_RTMPTS:
    family = CURLPROTO_RTMPT;
    break;

  case CURLPROTO_RTMPE:
    family = CURLPROTO_RTMPE;
    break;

  case CURLPROTO_RTMPTE:
    family = CURLPROTO_RTMPTE;
    break;

  case CURLPROTO_GOPHER:
    family = CURLPROTO_GOPHER;
    break;

  case CURLPROTO_SMB:
  case CURLPROTO_SMBS:
    family = CURLPROTO_SMB;
    break;

  default:
      family = 0;
      break;
  }

  return family;
}