xapian-core/common/socket_utils.h

   1 /** @file
   2  *  @brief Socket handling utilities.
   3  */
   4 /* Copyright (C) 2006-2023 Olly Betts
   5  * Copyright (C) 2008 Lemur Consulting Ltd
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  20  */
  21
  22 #ifndef XAPIAN_INCLUDED_SOCKET_UTILS_H
  23 #define XAPIAN_INCLUDED_SOCKET_UTILS_H
  24
  25 #include "safenetdb.h"
  26 #include "safeunistd.h"
  27
  28 #include <cerrno>
  29
  30 #ifdef __WIN32__
  31
  32 # include "safewinsock2.h"
  33
  34 # include <xapian/error.h>
  35
  36 /// Convert an fd (which might be a socket) to a WIN32 HANDLE.
  37 extern HANDLE fd_to_handle(int fd);
  38
  39 /// Close an fd, which might be a socket.
  40 extern void close_fd_or_socket(int fd);
  41
  42 /** Class to initialise winsock and keep it initialised while we use it.
  43  *
  44  *  We need to get WinSock initialised before we use it, and make it clean up
  45  *  after we've finished using it.  This class performs this initialisation when
  46  *  constructed and cleans up when destructed.  Multiple instances of the class
  47  *  may be instantiated - windows keeps a count of the number of times that
  48  *  WSAStartup has been successfully called and only performs the actual cleanup
  49  *  when WSACleanup has been called the same number of times.
  50  *
  51  *  Simply ensure that an instance of this class is initialised whenever we're
  52  *  doing socket handling.  This class can be used as a mixin class (just
  53  *  inherit from it) or instantiated as a class member or local variable).
  54  */
  55 struct WinsockInitializer {
  56     WinsockInitializer() {
  57         WSADATA wsadata;
  58         int wsaerror = WSAStartup(MAKEWORD(2, 2), &wsadata);
  59         // FIXME - should we check the returned information in wsadata to check
  60         // that we have a version of winsock which is recent enough for us?
  61
  62         if (wsaerror != 0) {
  63             throw Xapian::NetworkError("Failed to initialize winsock", wsaerror);
  64         }
  65     }
  66
  67     ~WinsockInitializer() {
  68         WSACleanup();
  69     }
  70 };
  71
  72 /** Get the errno value of the last error to occur due to a socket operation.
  73  *
  74  *  This is specific to the calling thread.
  75  *
  76  *  This is needed because some platforms (Windows) separate errors due to
  77  *  socket operations from other errors.  On platforms which don't do this,
  78  *  the return value will be the value of errno.
  79  */
  80 inline int socket_errno() {
  81     int wsa_err = WSAGetLastError();
  82     switch (wsa_err) {
  83 # ifdef EADDRINUSE
  84         case WSAEADDRINUSE: return EADDRINUSE;
  85 # endif
  86 # ifdef ETIMEDOUT
  87         case WSAETIMEDOUT: return ETIMEDOUT;
  88 # endif
  89 # ifdef EINPROGRESS
  90         case WSAEINPROGRESS: return EINPROGRESS;
  91 # endif
  92         default: return wsa_err;
  93     }
  94 }
  95
  96 /* Newer compilers define these, in which case we map to those already defined
  97  * values in socket_errno() above.
  98  */
  99 # ifndef EADDRINUSE
 100 #  define EADDRINUSE WSAEADDRINUSE
 101 # endif
 102 # ifndef ETIMEDOUT
 103 #  define ETIMEDOUT WSAETIMEDOUT
 104 # endif
 105 # ifndef EINPROGRESS
 106 #  define EINPROGRESS WSAEINPROGRESS
 107 # endif
 108
 109 // We must call closesocket() (instead of just close()) under __WIN32__ or
 110 // else the socket remains in the CLOSE_WAIT state.
 111 # define CLOSESOCKET(S) closesocket(S)
 112
 113 #else
 114
 115 // For INET_ADDRSTRLEN and INET6_ADDRSTRLEN.
 116 #include <arpa/inet.h>
 117
 118 // There's no distinction between sockets and other fds on UNIX.
 119 inline void close_fd_or_socket(int fd) { close(fd); }
 120
 121 inline int socket_errno() { return errno; }
 122
 123 # define CLOSESOCKET(S) close(S)
 124
 125 #endif
 126
 127 /** Attempt to set socket-level timeouts.
 128  *
 129  *  These aren't supported by all platforms, and some platforms allow them to
 130  *  set but ignore them, so we can't easily report failure.
 131  *
 132  *  Also sets SO_KEEPALIVE (if supported), which should ensure a stuck
 133  *  connection will eventually time out, though it may take up to ~2 hours.
 134  */
 135 void set_socket_timeouts(int fd, double timeout);
 136
 137 constexpr size_t PRETTY_IP6_LEN =
 138     (INET6_ADDRSTRLEN > INET_ADDRSTRLEN ? INET6_ADDRSTRLEN : INET_ADDRSTRLEN);
 139
 140 int pretty_ip6(const void* p, char* buf);
 141
 142 #endif // XAPIAN_INCLUDED_SOCKET_UTILS_H