xapian-core  1.4.21
tcpclient.cc
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1 
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 }
Open a TCP connection to a server.
RemoteConnection class used by the remote backend.
include <sys/select.h> with portability workarounds.
Indicates a timeout expired while communicating with a remote database.
Definition: error.h:845
include <sys/socket.h> with portability workarounds.
#define SOCKLEN_T
Definition: config.h:371
STL namespace.
Convert types to std::string.
include <netdb.h>, with portability workarounds.
#define SOCK_CLOEXEC
Definition: safesyssocket.h:93
Hierarchy of classes which Xapian can throw as exceptions.
Resolve hostnames and ip addresses.
Socket handling utilities.
int open_socket(const std::string &hostname, int port, double timeout_connect, bool tcp_nodelay)
Attempt to open a TCP/IP socket connection to a server.
Definition: tcpclient.cc:56
Indicates a problem communicating with a remote database.
Definition: error.h:803
void to_timeval(double t, struct timeval *tv)
Fill in struct timeval from number of seconds in a double.
Definition: realtime.h:110
#define CLOSESOCKET(S)
Functions for handling a time or time interval in a double.
int socket_errno()
include <fcntl.h>, but working around broken platforms.
#define FLAG_NAME