Example #1
0
void SctpSocket::OnException()
{
	if (Connecting())
	{
#ifdef ENABLE_SOCKS4
		if (Socks4())
			OnSocks4ConnectFailed();
		else
#endif
		if (GetConnectionRetry() == -1 ||
			(GetConnectionRetry() &&
			 GetConnectionRetries() < GetConnectionRetry() ))
		{
			// even though the connection failed at once, only retry after
			// the connection timeout
			// should we even try to connect again, when CheckConnect returns
			// false it's because of a connection error - not a timeout...
		}
		else
		{
			SetConnecting(false); // tnx snibbe
			SetCloseAndDelete();
			OnConnectFailed();
		}
		return;
	}
	// %! exception doesn't always mean something bad happened, this code should be reworked
	// errno valid here?
	int err = SoError();
	Handler().LogError(this, "exception on select", err, StrError(err), LOG_LEVEL_FATAL);
	SetCloseAndDelete();
}
Example #2
0
void SctpSocket::OnWrite()
{
	if (Connecting())
	{
		int err = SoError();

		// don't reset connecting flag on error here, we want the OnConnectFailed timeout later on
		/// \todo add to read fd_set here
		if (!err) // ok
		{
			Set(!IsDisableRead(), false);
			SetConnecting(false);
			SetCallOnConnect();
			return;
		}
		Handler().LogError(this, "sctp: connect failed", err, StrError(err), LOG_LEVEL_FATAL);
		Set(false, false); // no more monitoring because connection failed

		// failed
#ifdef ENABLE_SOCKS4
		if (Socks4())
		{
			OnSocks4ConnectFailed();
			return;
		}
#endif
		if (GetConnectionRetry() == -1 ||
			(GetConnectionRetry() && GetConnectionRetries() < GetConnectionRetry()) )
		{
			// even though the connection failed at once, only retry after
			// the connection timeout.
			// should we even try to connect again, when CheckConnect returns
			// false it's because of a connection error - not a timeout...
			return;
		}
		SetConnecting(false);
		SetCloseAndDelete( true );
		/// \todo state reason why connect failed
		OnConnectFailed();
		return;
	}
}
Example #3
0
void 
connect_server()
{
  struct Client *client = make_client(NULL);
  struct Server *server = make_server(client);
  struct Module *protomod;
  char modes[MODEBUFLEN+1] = "";
  int i, j = 0;

  protomod = find_module(Connect.protocol, NO);
  if(protomod == NULL)
  {
    ilog(L_CRIT, "Unable to connect to uplink, protocol module %s not found.",
        Connect.protocol);
    services_die("Connect error", NO);
  }

  ServerModeList = (struct ModeList *)modsym(protomod->handle, "ModeList");
  for(i = 0; ServerModeList[i].letter != '\0'; i++)
  {
    modes[j++] = ServerModeList[i].letter;
    if(j > MODEBUFLEN)
      break;
  }
  modes[j] = '\0';

  ilog(L_DEBUG, "Loaded server mode list %p %s %d", ServerModeList, modes, j);

  strlcpy(server->pass, Connect.password, sizeof(server->pass));
  strlcpy(client->name, Connect.name, sizeof(client->name));
  strlcpy(client->host, Connect.host, sizeof(client->host));

  SetConnecting(client);
  client->from = client;
    
  dlinkAdd(client, &client->node, &global_client_list);

  if(comm_open(&server->fd, AF_INET, SOCK_STREAM, 0, NULL) < 0)
  {
    ilog(L_CRIT, "connect_server: Could not open socket");
    exit(1);
  }

  comm_connect_tcp(&server->fd, Connect.host, Connect.port,
      NULL, 0, serv_connect_callback, client, AF_INET, CONNECTTIMEOUT);

  eventAdd("Server connection check", try_reconnect, NULL, 60);
}
Example #4
0
int SctpSocket::Open(SocketAddress& ad)
{
	if (!ad.IsValid())
	{
		Handler().LogError(this, "SctpSocket", -1, "invalid address", LOG_LEVEL_ERROR);
		return -1;
	}
	if (GetSocket() == INVALID_SOCKET)
	{
		Attach(CreateSocket(ad.GetFamily(), m_type, "sctp"));
	}
	if (GetSocket() != INVALID_SOCKET)
	{
		if (!SetNonblocking(true))
		{
			return -1;
		}
		int n = connect(GetSocket(), ad, ad);
		if (n == -1)
		{
			// check error code that means a connect is in progress
#ifdef _WIN32
			if (Errno == WSAEWOULDBLOCK)
#else
			if (Errno == EINPROGRESS)
#endif
			{
				Handler().LogError(this, "connect: connection pending", Errno, StrError(Errno), LOG_LEVEL_INFO);
				SetConnecting( true ); // this flag will control fd_set's
			}
			else
			{
				Handler().LogError(this, "SctpSocket", -1, "connect() failed", LOG_LEVEL_ERROR);
			}
		}
		return n;
	}
	return -1;
}
Example #5
0
void SctpSocket::OnConnectTimeout()
{
	Handler().LogError(this, "connect", -1, "connect timeout", LOG_LEVEL_FATAL);
#ifdef ENABLE_SOCKS4
	if (Socks4())
	{
		OnSocks4ConnectFailed();
		// retry direct connection
	}
	else
#endif
	if (GetConnectionRetry() == -1 ||
		(GetConnectionRetry() && GetConnectionRetries() < GetConnectionRetry()) )
	{
		IncreaseConnectionRetries();
		// ask socket via OnConnectRetry callback if we should continue trying
		if (OnConnectRetry())
		{
			SetRetryClientConnect();
		}
		else
		{
			SetCloseAndDelete( true );
			/// \todo state reason why connect failed
			OnConnectFailed();
		}
	}
	else
	{
		SetCloseAndDelete(true);
		/// \todo state reason why connect failed
		OnConnectFailed();
	}
	//
	SetConnecting(false);
}
Example #6
0
int SctpSocket::AddConnection(SocketAddress& ad)
{
	if (!ad.IsValid())
	{
		Handler().LogError(this, "SctpSocket", -1, "invalid address", LOG_LEVEL_ERROR);
		return -1;
	}
	if (GetSocket() == INVALID_SOCKET)
	{
		Handler().LogError(this, "SctpSocket", -1, "AddConnection called with invalid file descriptor", LOG_LEVEL_ERROR);
		return -1;
	}
//	int n = sctp_connectx(GetSocket(), ad, ad);
	int n = sctp_connectx(GetSocket(), ad, 1, NULL);
	if (n == -1)
	{
		Handler().LogError(this, "SctpSocket", -1, "sctp_connectx() failed", LOG_LEVEL_ERROR);
	}
	else
	{
		SetConnecting();
	}
	return n;
}
Example #7
0
bool TcpSocket::Open(SocketAddress& ad,SocketAddress& bind_ad,bool skip_socks)
{
	if (!ad.IsValid())
	{
		Handler().LogError(this, "Open", 0, "Invalid SocketAddress", LOG_LEVEL_FATAL);
		SetCloseAndDelete();
		return false;
	}
	if (Handler().GetCount() >= Handler().MaxCount())
	{
		Handler().LogError(this, "Open", 0, "no space left for more sockets", LOG_LEVEL_FATAL);
		SetCloseAndDelete();
		return false;
	}
	SetConnecting(false);
#ifdef ENABLE_SOCKS4
	SetSocks4(false);
#endif
	// check for pooling
#ifdef ENABLE_POOL
	if (Handler().PoolEnabled())
	{
		ISocketHandler::PoolSocket *pools = Handler().FindConnection(SOCK_STREAM, "tcp", ad);
		if (pools)
		{
			CopyConnection( pools );
			delete pools;

			SetIsClient();
			SetCallOnConnect(); // ISocketHandler must call OnConnect
			Handler().LogError(this, "SetCallOnConnect", 0, "Found pooled connection", LOG_LEVEL_INFO);
			return true;
		}
	}
#endif
	// if not, create new connection
	SOCKET s = CreateSocket(ad.GetFamily(), SOCK_STREAM, "tcp");
	if (s == INVALID_SOCKET)
	{
		return false;
	}
	// socket must be nonblocking for async connect
	if (!SetNonblocking(true, s))
	{
		SetCloseAndDelete();
		closesocket(s);
		return false;
	}
#ifdef ENABLE_POOL
	SetIsClient(); // client because we connect
#endif
	SetClientRemoteAddress(ad);
	int n = 0;
	if (bind_ad.GetPort() != 0)
	{
		bind(s, bind_ad, bind_ad);
	}
#ifdef ENABLE_SOCKS4
	if (!skip_socks && GetSocks4Host() && GetSocks4Port())
	{
		Ipv4Address sa(GetSocks4Host(), GetSocks4Port());
		{
			std::string sockshost;
			Utility::l2ip(GetSocks4Host(), sockshost);
			Handler().LogError(this, "Open", 0, "Connecting to socks4 server @ " + sockshost + ":" +
				Utility::l2string(GetSocks4Port()), LOG_LEVEL_INFO);
		}
		SetSocks4();
		n = connect(s, sa, sa);
		SetRemoteAddress(sa);
	}
	else
#endif
	{
		n = connect(s, ad, ad);
		SetRemoteAddress(ad);
	}
	if (n == -1)
	{
		// check error code that means a connect is in progress
#ifdef _WIN32
		if (Errno == WSAEWOULDBLOCK)
#else
		if (Errno == EINPROGRESS)
#endif
		{
			Attach(s);
			SetConnecting( true ); // this flag will control fd_set's
		}
		else
#ifdef ENABLE_SOCKS4
		if (Socks4() && Handler().Socks4TryDirect() ) // retry
		{
			closesocket(s);
			return Open(ad, true);
		}
		else
#endif
#ifdef ENABLE_RECONNECT
		if (Reconnect())
		{
			Handler().LogError(this, "connect: failed, reconnect pending", Errno, StrError(Errno), LOG_LEVEL_INFO);
			Attach(s);
			SetConnecting( true ); // this flag will control fd_set's
		}
		else
#endif
		{
			Handler().LogError(this, "connect: failed", Errno, StrError(Errno), LOG_LEVEL_FATAL);
			SetCloseAndDelete();
			closesocket(s);
			return false;
		}
	}
	else
	{
		Attach(s);
		SetCallOnConnect(); // ISocketHandler must call OnConnect
	}

	// 'true' means connected or connecting(not yet connected)
	// 'false' means something failed
	return true; //!Connecting();
}
Example #8
0
/** Read a 'packet' of data from a connection and process it.  Read in
 * 8k chunks to give a better performance rating (for server
 * connections).  Do some tricky stuff for client connections to make
 * sure they don't do any flooding >:-) -avalon
 * @param cptr Client from which to read data.
 * @param socket_ready If non-zero, more data can be read from the client's socket.
 * @return Positive number on success, zero on connection-fatal failure, negative
 *   if user is killed.
 */
static int read_packet(struct Client *cptr, int socket_ready)
{
  unsigned int dolen = 0;
  unsigned int length = 0;

  if (socket_ready &&
      !(IsUser(cptr) &&
	DBufLength(&(cli_recvQ(cptr))) > feature_uint(FEAT_CLIENT_FLOOD))) {
#if defined(USE_SSL)
    switch (client_recv(cptr, readbuf, sizeof(readbuf), &length)) {
#else
    switch (os_recv_nonb(cli_fd(cptr), readbuf, sizeof(readbuf), &length)) {
#endif
    case IO_SUCCESS:
      if (length)
      {
        cli_lasttime(cptr) = CurrentTime;
        ClearPingSent(cptr);
        ClrFlag(cptr, FLAG_NONL);
        if (cli_lasttime(cptr) > cli_since(cptr))
          cli_since(cptr) = cli_lasttime(cptr);
      }
      break;
    case IO_BLOCKED:
      break;
    case IO_FAILURE:
      cli_error(cptr) = errno;
      /* SetFlag(cptr, FLAG_DEADSOCKET); */
      return 0;
    }
  }

  /*
   * For server connections, we process as many as we can without
   * worrying about the time of day or anything :)
   */
  if (length > 0 && IsServer(cptr))
    return server_dopacket(cptr, readbuf, length);
  else if (length > 0 && (IsHandshake(cptr) || IsConnecting(cptr)))
    return connect_dopacket(cptr, readbuf, length);
  else
  {
    /*
     * Before we even think of parsing what we just read, stick
     * it on the end of the receive queue and do it when its
     * turn comes around.
     */
    if (length > 0 && dbuf_put(cptr, &(cli_recvQ(cptr)), readbuf, length) == 0)
      return exit_client(cptr, cptr, &me, "dbuf_put fail");

    if ((DBufLength(&(cli_recvQ(cptr))) > feature_uint(FEAT_CLIENT_FLOOD))
         && !IsChannelService(cptr))
      return exit_client(cptr, cptr, &me, "Excess Flood");

    while (DBufLength(&(cli_recvQ(cptr))) && !NoNewLine(cptr) &&
           (IsTrusted(cptr) || IsChannelService(cptr) || cli_since(cptr) - CurrentTime < 10))
    {
      dolen = dbuf_getmsg(&(cli_recvQ(cptr)), cli_buffer(cptr), BUFSIZE);
      /*
       * Devious looking...whats it do ? well..if a client
       * sends a *long* message without any CR or LF, then
       * dbuf_getmsg fails and we pull it out using this
       * loop which just gets the next 512 bytes and then
       * deletes the rest of the buffer contents.
       * -avalon
       */
      if (dolen == 0)
      {
        if (DBufLength(&(cli_recvQ(cptr))) < 510)
          SetFlag(cptr, FLAG_NONL);
        else
        {
          /* More than 512 bytes in the line - drop the input and yell
           * at the client.
           */
          DBufClear(&(cli_recvQ(cptr)));
          send_reply(cptr, ERR_INPUTTOOLONG);
        }
      }
      else if (client_dopacket(cptr, dolen) == CPTR_KILLED)
        return CPTR_KILLED;
      /*
       * If it has become registered as a Server
       * then skip the per-message parsing below.
       */
      if (IsHandshake(cptr) || IsServer(cptr))
      {
        while (-1)
        {
          dolen = dbuf_get(&(cli_recvQ(cptr)), readbuf, sizeof(readbuf));
          if (dolen <= 0)
            return 1;
          else if (dolen == 0)
          {
            if (DBufLength(&(cli_recvQ(cptr))) < 510)
              SetFlag(cptr, FLAG_NONL);
            else {
              DBufClear(&(cli_recvQ(cptr)));
              /* send_reply(cptr, ERR_INPUTTOOLONG); */
            }
          }
          else if ((IsServer(cptr) &&
                    server_dopacket(cptr, readbuf, dolen) == CPTR_KILLED) ||
                   (!IsServer(cptr) &&
                    connect_dopacket(cptr, readbuf, dolen) == CPTR_KILLED))
            return CPTR_KILLED;
        }
      }
    }

    /* If there's still data to process, wait 2 seconds first */
    if (DBufLength(&(cli_recvQ(cptr))) && !NoNewLine(cptr) &&
	!t_onqueue(&(cli_proc(cptr))))
    {
      Debug((DEBUG_LIST, "Adding client process timer for %C", cptr));
      cli_freeflag(cptr) |= FREEFLAG_TIMER;
      timer_add(&(cli_proc(cptr)), client_timer_callback, cli_connect(cptr),
		TT_RELATIVE, 2);
    }
  }
  return 1;
}

/** Start a connection to another server.
 * @param aconf Connect block data for target server.
 * @param by Client who requested the connection (if any).
 * @return Non-zero on success; zero on failure.
 */
int connect_server(struct ConfItem* aconf, struct Client* by)
{
  struct Client*   cptr = 0;
  assert(0 != aconf);

  if (aconf->dns_pending) {
    sendto_opmask(0, SNO_OLDSNO, "Server %s connect DNS pending",
                  aconf->name);
    return 0;
  }
  Debug((DEBUG_NOTICE, "Connect to %s[@%s]", aconf->name,
         ircd_ntoa(&aconf->address.addr)));

  if ((cptr = FindClient(aconf->name))) {
    if (IsServer(cptr) || IsMe(cptr)) {
      sendto_opmask(0, SNO_OLDSNO, "Server %s already present from %s",
                    aconf->name, cli_name(cli_from(cptr)));
      if (by && IsUser(by) && !MyUser(by)) {
        sendcmdto_one(&me, CMD_NOTICE, by, "%C :Server %s already present "
                      "from %s", by, aconf->name, cli_name(cli_from(cptr)));
      }
      return 0;
    }
    else if (IsHandshake(cptr) || IsConnecting(cptr)) {
      if (by && IsUser(by)) {
        sendcmdto_one(&me, CMD_NOTICE, by, "%C :Connection to %s already in "
                      "progress", by, cli_name(cptr));
      }
      return 0;
    }
  }
  /*
   * If we don't know the IP# for this host and it is a hostname and
   * not a ip# string, then try and find the appropriate host record.
   */
  if (!irc_in_addr_valid(&aconf->address.addr)
      && !ircd_aton(&aconf->address.addr, aconf->host)) {
    char buf[HOSTLEN + 1];

    host_from_uh(buf, aconf->host, HOSTLEN);
    gethost_byname(buf, connect_dns_callback, aconf);
    aconf->dns_pending = 1;
    return 0;
  }
  cptr = make_client(NULL, STAT_UNKNOWN_SERVER);

  /*
   * Copy these in so we have something for error detection.
   */
  ircd_strncpy(cli_name(cptr), aconf->name, HOSTLEN);
  ircd_strncpy(cli_sockhost(cptr), aconf->host, HOSTLEN);

  /*
   * Attach config entries to client here rather than in
   * completed_connection. This to avoid null pointer references
   */
  attach_confs_byhost(cptr, aconf->host, CONF_SERVER);

  if (!find_conf_byhost(cli_confs(cptr), aconf->host, CONF_SERVER)) {
    sendto_opmask(0, SNO_OLDSNO, "Host %s is not enabled for "
                  "connecting: no Connect block", aconf->name);
    if (by && IsUser(by) && !MyUser(by)) {
      sendcmdto_one(&me, CMD_NOTICE, by, "%C :Connect to host %s failed: no "
                    "Connect block", by, aconf->name);
    }
    det_confs_butmask(cptr, 0);
    free_client(cptr);
    return 0;
  }
  /*
   * attempt to connect to the server in the conf line
   */
  if (!connect_inet(aconf, cptr)) {
    if (by && IsUser(by) && !MyUser(by)) {
      sendcmdto_one(&me, CMD_NOTICE, by, "%C :Couldn't connect to %s", by,
                    cli_name(cptr));
    }
    det_confs_butmask(cptr, 0);
    free_client(cptr);
    return 0;
  }
  /*
   * NOTE: if we're here we have a valid C:Line and the client should
   * have started the connection and stored the remote address/port and
   * ip address name in itself
   *
   * The socket has been connected or connect is in progress.
   */
  make_server(cptr);
  if (by && IsUser(by)) {
    ircd_snprintf(0, cli_serv(cptr)->by, sizeof(cli_serv(cptr)->by), "%s%s",
		  NumNick(by));
    assert(0 == cli_serv(cptr)->user);
    cli_serv(cptr)->user = cli_user(by);
    cli_user(by)->refcnt++;
  }
  else {
    *(cli_serv(cptr))->by = '\0';
    /* strcpy(cptr->serv->by, "Auto"); */
  }
  cli_serv(cptr)->up = &me;
  SetConnecting(cptr);

  if (cli_fd(cptr) > HighestFd)
    HighestFd = cli_fd(cptr);

  LocalClientArray[cli_fd(cptr)] = cptr;

  Count_newunknown(UserStats);
  /* Actually we lie, the connect hasn't succeeded yet, but we have a valid
   * cptr, so we register it now.
   * Maybe these two calls should be merged.
   */
  add_client_to_list(cptr);
  hAddClient(cptr);
/*    nextping = CurrentTime; */

  return (s_state(&cli_socket(cptr)) == SS_CONNECTED) ?
    completed_connection(cptr) : 1;
}

/** Find the real hostname for the host running the server (or one which
 * matches the server's name) and its primary IP#.  Hostname is stored
 * in the client structure passed as a pointer.
 */
void init_server_identity(void)
{
  const struct LocalConf* conf = conf_get_local();
  assert(0 != conf);

  ircd_strncpy(cli_name(&me), conf->name, HOSTLEN);
  SetYXXServerName(&me, conf->numeric);
}

/** Process events on a client socket.
 * @param ev Socket event structure that has a struct Connection as
 *   its associated data.
 */
static void client_sock_callback(struct Event* ev)
{
  struct Client* cptr;
  struct Connection* con;
  char *fmt = "%s";
  char *fallback = 0;

  assert(0 != ev_socket(ev));
  assert(0 != s_data(ev_socket(ev)));

  con = (struct Connection*) s_data(ev_socket(ev));

  assert(0 != con_client(con) || ev_type(ev) == ET_DESTROY);

  cptr = con_client(con);

  assert(0 == cptr || con == cli_connect(cptr));

  switch (ev_type(ev)) {
  case ET_DESTROY:
    con_freeflag(con) &= ~FREEFLAG_SOCKET;

    if (!con_freeflag(con) && !cptr)
      free_connection(con);
#if defined(USE_SSL)
    ssl_free(ev_socket(ev));
#endif
    break;

  case ET_CONNECT: /* socket connection completed */
    if (!completed_connection(cptr) || IsDead(cptr))
      fallback = cli_info(cptr);
    break;

  case ET_ERROR: /* an error occurred */
    fallback = cli_info(cptr);
    cli_error(cptr) = ev_data(ev);
    /* If the OS told us we have a bad file descriptor, we should
     * record that for future reference.
     */
    if (cli_error(cptr) == EBADF)
      cli_fd(cptr) = -1;
    if (s_state(&(con_socket(con))) == SS_CONNECTING) {
      completed_connection(cptr);
      /* for some reason, the os_get_sockerr() in completed_connection()
       * can return 0 even when ev_data(ev) indicates a real error, so
       * re-assign the client error here.
       */
      cli_error(cptr) = ev_data(ev);
      break;
    }
    /*FALLTHROUGH*/
  case ET_EOF: /* end of file on socket */
    Debug((DEBUG_ERROR, "READ ERROR: fd = %d %d", cli_fd(cptr),
	   cli_error(cptr)));
    SetFlag(cptr, FLAG_DEADSOCKET);
    if ((IsServer(cptr) || IsHandshake(cptr)) && cli_error(cptr) == 0) {
      exit_client_msg(cptr, cptr, &me, "Server %s closed the connection (%s)",
		      cli_name(cptr), cli_serv(cptr)->last_error_msg);
      return;
    } else {
      fmt = "Read error: %s";
      fallback = "EOF from client";
    }
    break;

  case ET_WRITE: /* socket is writable */
    ClrFlag(cptr, FLAG_BLOCKED);
    if (cli_listing(cptr) && MsgQLength(&(cli_sendQ(cptr))) < 2048)
      list_next_channels(cptr);
    Debug((DEBUG_SEND, "Sending queued data to %C", cptr));
    send_queued(cptr);
    break;

  case ET_READ: /* socket is readable */
    if (!IsDead(cptr)) {
      Debug((DEBUG_DEBUG, "Reading data from %C", cptr));
      if (read_packet(cptr, 1) == 0) /* error while reading packet */
	fallback = "EOF from client";
    }
    break;

  default:
    assert(0 && "Unrecognized socket event in client_sock_callback()");
    break;
  }

  assert(0 == cptr || 0 == cli_connect(cptr) || con == cli_connect(cptr));

  if (fallback) {
    const char* msg = (cli_error(cptr)) ? strerror(cli_error(cptr)) : fallback;
    if (!msg)
      msg = "Unknown error";
    exit_client_msg(cptr, cptr, &me, fmt, msg);
  }
}

/** Process a timer on client socket.
 * @param ev Timer event that has a struct Connection as its
 * associated data.
 */
static void client_timer_callback(struct Event* ev)
{
  struct Client* cptr;
  struct Connection* con;

  assert(0 != ev_timer(ev));
  assert(0 != t_data(ev_timer(ev)));
  assert(ET_DESTROY == ev_type(ev) || ET_EXPIRE == ev_type(ev));

  con = (struct Connection*) t_data(ev_timer(ev));

  assert(0 != con_client(con) || ev_type(ev) == ET_DESTROY);

  cptr = con_client(con);

  assert(0 == cptr || con == cli_connect(cptr));

  if (ev_type(ev)== ET_DESTROY) {
    con_freeflag(con) &= ~FREEFLAG_TIMER; /* timer has expired... */

    if (!con_freeflag(con) && !cptr)
      free_connection(con); /* client is being destroyed */
  } else {
    Debug((DEBUG_LIST, "Client process timer for %C expired; processing",
	   cptr));
    read_packet(cptr, 0); /* read_packet will re-add timer if needed */
  }

  assert(0 == cptr || 0 == cli_connect(cptr) || con == cli_connect(cptr));
}
Example #9
0
/** Start a connection to another server.
 * @param aconf Connect block data for target server.
 * @param by Client who requested the connection (if any).
 * @return Non-zero on success; zero on failure.
 */
int connect_server(struct ConfItem* aconf, struct Client* by)
{
  struct Client*   cptr = 0;
  assert(0 != aconf);

  if (aconf->dns_pending) {
    sendto_opmask_butone(0, SNO_OLDSNO, "Server %s connect DNS pending",
                         aconf->name);
    return 0;
  }
  Debug((DEBUG_NOTICE, "Connect to %s[@%s]", aconf->name,
         ircd_ntoa(&aconf->address.addr)));

  if ((cptr = FindClient(aconf->name))) {
    if (IsServer(cptr) || IsMe(cptr)) {
      sendto_opmask_butone(0, SNO_OLDSNO, "Server %s already present from %s", 
                           aconf->name, cli_name(cli_from(cptr)));
      if (by && IsUser(by) && !MyUser(by)) {
        sendcmdto_one(&me, CMD_NOTICE, by, "%C :Server %s already present "
                      "from %s", by, aconf->name, cli_name(cli_from(cptr)));
      }
      return 0;
    }
    else if (IsHandshake(cptr) || IsConnecting(cptr)) {
      if (by && IsUser(by)) {
        sendcmdto_one(&me, CMD_NOTICE, by, "%C :Connection to %s already in "
                      "progress", by, cli_name(cptr));
      }
      return 0;
    }
  }
  /*
   * If we don't know the IP# for this host and it is a hostname and
   * not a ip# string, then try and find the appropriate host record.
   */
  if (!irc_in_addr_valid(&aconf->address.addr)
      && !ircd_aton(&aconf->address.addr, aconf->host)) {
    char buf[HOSTLEN + 1];

    host_from_uh(buf, aconf->host, HOSTLEN);
    gethost_byname(buf, connect_dns_callback, aconf);
    aconf->dns_pending = 1;
    return 0;
  }
  cptr = make_client(NULL, STAT_UNKNOWN_SERVER);

  /*
   * Copy these in so we have something for error detection.
   */
  ircd_strncpy(cli_name(cptr), aconf->name, HOSTLEN);
  ircd_strncpy(cli_sockhost(cptr), aconf->host, HOSTLEN);

  /*
   * Attach config entries to client here rather than in
   * completed_connection. This to avoid null pointer references
   */
  attach_confs_byhost(cptr, aconf->host, CONF_SERVER);

  if (!find_conf_byhost(cli_confs(cptr), aconf->host, CONF_SERVER)) {
    sendto_opmask_butone(0, SNO_OLDSNO, "Host %s is not enabled for "
                         "connecting: no Connect block", aconf->name);
    if (by && IsUser(by) && !MyUser(by)) {
      sendcmdto_one(&me, CMD_NOTICE, by, "%C :Connect to host %s failed: no "
                    "Connect block", by, aconf->name);
    }
    det_confs_butmask(cptr, 0);
    free_client(cptr);
    return 0;
  }
  /*
   * attempt to connect to the server in the conf line
   */
  if (!connect_inet(aconf, cptr)) {
    if (by && IsUser(by) && !MyUser(by)) {
      sendcmdto_one(&me, CMD_NOTICE, by, "%C :Couldn't connect to %s", by,
                    cli_name(cptr));
    }
    det_confs_butmask(cptr, 0);
    free_client(cptr);
    return 0;
  }
  /*
   * NOTE: if we're here we have a valid C:Line and the client should
   * have started the connection and stored the remote address/port and
   * ip address name in itself
   *
   * The socket has been connected or connect is in progress.
   */
  make_server(cptr);
  if (by && IsUser(by)) {
    ircd_snprintf(0, cli_serv(cptr)->by, sizeof(cli_serv(cptr)->by), "%s%s",
		  NumNick(by));
    assert(0 == cli_serv(cptr)->user);
    cli_serv(cptr)->user = cli_user(by);
    cli_user(by)->refcnt++;
  }
  else {
    *(cli_serv(cptr))->by = '\0';
    /* strcpy(cptr->serv->by, "Auto"); */
  }
  cli_serv(cptr)->up = &me;
  SetConnecting(cptr);

  if (cli_fd(cptr) > HighestFd)
    HighestFd = cli_fd(cptr);

  LocalClientArray[cli_fd(cptr)] = cptr;

  Count_newunknown(UserStats);
  /* Actually we lie, the connect hasn't succeeded yet, but we have a valid
   * cptr, so we register it now.
   * Maybe these two calls should be merged.
   */
  add_client_to_list(cptr);
  hAddClient(cptr);
/*    nextping = CurrentTime; */

  return (s_state(&cli_socket(cptr)) == SS_CONNECTED) ?
    completed_connection(cptr) : 1;
}