xapian-core/net/tcpclient.cc

   1 /** @file
   2  * @brief Open a TCP connection to a server.
   3  */
   4 /* Copyright 1999,2000,2001 BrightStation PLC
   5  * Copyright 2002 Ananova Ltd
   6  * Copyright 2004,2005,2006,2007,2008,2010,2012,2013,2015,2017 Olly Betts
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of the
  11  * License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
  21  * USA
  22  */
  23
  24 #include <config.h>
  25
  26 #include "tcpclient.h"
  27
  28 #include "remoteconnection.h"
  29 #include "resolver.h"
  30 #include "str.h"
  31 #include <xapian/error.h>
  32
  33 #include "realtime.h"
  34 #include "safefcntl.h"
  35 #include "safenetdb.h"
  36 #include "safesyssocket.h"
  37 #include "socket_utils.h"
  38
  39 #ifdef HAVE_POLL_H
  40 # include <poll.h>
  41 #else
  42 # include "safesysselect.h"
  43 #endif
  44
  45 #include <cerrno>
  46 #include <cmath>
  47 #include <cstring>
  48 #ifndef __WIN32__
  49 # include <netinet/in.h>
  50 # include <netinet/tcp.h>
  51 #endif
  52
  53 using namespace std;
  54
  55 int
  56 TcpClient::open_socket(const std::string & hostname, int port,
  57                        double timeout_connect, bool tcp_nodelay)
  58 {
  59     int socketfd = -1;
  60     int connect_errno = 0;
  61     for (auto&& r : Resolver(hostname, port)) {
  62         int socktype = r.ai_socktype | SOCK_CLOEXEC;
  63 #ifdef SOCK_NONBLOCK
  64         socktype |= SOCK_NONBLOCK;
  65 #endif
  66         int fd = socket(r.ai_family, socktype, r.ai_protocol);
  67         if (fd == -1)
  68             continue;
  69
  70 #if !defined __WIN32__ && defined F_SETFD && defined FD_CLOEXEC
  71         // We can't use a preprocessor check on the *value* of SOCK_CLOEXEC as
  72         // on Linux SOCK_CLOEXEC is an enum, with '#define SOCK_CLOEXEC
  73         // SOCK_CLOEXEC' to allow '#ifdef SOCK_CLOEXEC' to work.
  74         if (SOCK_CLOEXEC == 0)
  75             (void)fcntl(fd, F_SETFD, FD_CLOEXEC);
  76 #endif
  77
  78 #ifndef SOCK_NONBLOCK
  79 #ifdef __WIN32__
  80         ULONG enabled = 1;
  81         int rc = ioctlsocket(fd, FIONBIO, &enabled);
  82 #define FLAG_NAME "FIONBIO"
  83 #elif defined O_NONBLOCK
  84         int rc = fcntl(fd, F_SETFL, O_NONBLOCK);
  85 #define FLAG_NAME "O_NONBLOCK"
  86 #else
  87         int rc = fcntl(fd, F_SETFL, O_NDELAY);
  88 #define FLAG_NAME "O_NDELAY"
  89 #endif
  90         if (rc < 0) {
  91             int saved_errno = socket_errno(); // note down in case close hits an error
  92             CLOSESOCKET(fd);
  93             throw Xapian::NetworkError("Couldn't set " FLAG_NAME, saved_errno);
  94 #undef FLAG_NAME
  95         }
  96 #endif
  97
  98         if (tcp_nodelay) {
  99             int optval = 1;
 100             // 4th argument might need to be void* or char* - cast it to char*
 101             // since C++ allows implicit conversion to void* but not from
 102             // void*.
 103             if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
 104                            reinterpret_cast<char *>(&optval),
 105                            sizeof(optval)) < 0) {
 106                 int saved_errno = socket_errno(); // note down in case close hits an error
 107                 CLOSESOCKET(fd);
 108                 throw Xapian::NetworkError("Couldn't set TCP_NODELAY", saved_errno);
 109             }
 110         }
 111
 112         int retval = connect(fd, r.ai_addr, r.ai_addrlen);
 113         if (retval == 0) {
 114             socketfd = fd;
 115             break;
 116         }
 117
 118         int err = socket_errno();
 119         if (
 120 #ifdef __WIN32__
 121             WSAGetLastError() == WSAEWOULDBLOCK
 122 #else
 123             err == EINPROGRESS
 124 #endif
 125             ) {
 126             // Wait for the socket to be writable or give an error, with a
 127             // timeout.
 128 #ifdef HAVE_POLL
 129             struct pollfd fds;
 130             fds.fd = fd;
 131             fds.events = POLLOUT;
 132             do {
 133                 retval = poll(&fds, 1, int(timeout_connect * 1000));
 134             } while (retval < 0 && (errno == EINTR || errno == EAGAIN));
 135 #else
 136             fd_set fdset;
 137             FD_ZERO(&fdset);
 138             do {
 139                 FD_SET(fd, &fdset);
 140                 // FIXME: Reduce the timeout if we retry on EINTR.
 141                 struct timeval tv;
 142                 RealTime::to_timeval(timeout_connect, &tv);
 143                 retval = select(fd + 1, 0, &fdset, 0, &tv);
 144             } while (retval < 0 && (errno == EINTR || errno == EAGAIN));
 145 #endif
 146
 147             if (retval <= 0) {
 148                 int saved_errno = errno;
 149                 CLOSESOCKET(fd);
 150                 if (retval < 0)
 151                     throw Xapian::NetworkError("Couldn't connect (poll() or "
 152                                                "select() on socket failed)",
 153                                                saved_errno);
 154                 throw Xapian::NetworkTimeoutError("Timed out waiting to connect", ETIMEDOUT);
 155             }
 156
 157             err = 0;
 158             SOCKLEN_T len = sizeof(err);
 159
 160             // 4th argument might need to be void* or char* - cast it to char*
 161             // since C++ allows implicit conversion to void* but not from void*.
 162             retval = getsockopt(fd, SOL_SOCKET, SO_ERROR,
 163                                 reinterpret_cast<char *>(&err), &len);
 164
 165             if (retval < 0) {
 166                 int saved_errno = socket_errno(); // note down in case close hits an error
 167                 CLOSESOCKET(fd);
 168                 throw Xapian::NetworkError("Couldn't get socket options", saved_errno);
 169             }
 170             if (err == 0) {
 171                 // Connected successfully.
 172                 socketfd = fd;
 173                 break;
 174             }
 175         }
 176
 177         // Note down the error code for the first address we try, which seems
 178         // likely to be more helpful than the last in the case where they
 179         // differ.
 180         if (connect_errno == 0)
 181             connect_errno = err;
 182
 183         // Failed to connect.
 184         CLOSESOCKET(fd);
 185     }
 186
 187     if (socketfd == -1) {
 188         throw Xapian::NetworkError("Couldn't connect", connect_errno);
 189     }
 190
 191 #ifdef __WIN32__
 192     ULONG enabled = 0;
 193     ioctlsocket(socketfd, FIONBIO, &enabled);
 194 #else
 195     fcntl(socketfd, F_SETFL, 0);
 196 #endif
 197     return socketfd;
 198 }