1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2009 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Functions for doing things with sockets. With the advent of IPv6 this has
9 got messier, so that it's worth pulling out the code into separate functions
10 that other parts of Exim can call, expecially as there are now several
11 different places in the code where sockets are used. */
17 /*************************************************
19 *************************************************/
21 /* Socket creation happens in a number of places so it's packaged here for
25 type SOCK_DGRAM or SOCK_STREAM
26 af AF_INET or AF_INET6
28 Returns: socket number or -1 on failure
32 ip_socket(int type, int af)
34 int sock = socket(af, type, 0);
36 log_write(0, LOG_MAIN, "IPv%c socket creation failed: %s",
37 (af == AF_INET6)? '6':'4', strerror(errno));
45 /*************************************************
46 * Convert printing address to numeric *
47 *************************************************/
49 /* This function converts the textual form of an IP address into a numeric form
50 in an appropriate structure in an IPv6 environment. The getaddrinfo() function
51 can (apparently) handle more complicated addresses (e.g. those containing
52 scopes) than inet_pton() in some environments. We use hints to tell it that the
53 input must be a numeric address.
55 However, apparently some operating systems (or libraries) don't support
56 getaddrinfo(), so there is a build-time option to revert to inet_pton() (which
57 does not support scopes).
60 address textual form of the address
61 addr where to copy back the answer
63 Returns: nothing - failure provokes a panic-die
67 ip_addrinfo(uschar *address, struct sockaddr_in6 *saddr)
69 #ifdef IPV6_USE_INET_PTON
71 if (inet_pton(AF_INET6, CS address, &saddr->sin6_addr) != 1)
72 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
73 "IP address", address);
74 saddr->sin6_family = AF_INET6;
79 struct addrinfo hints, *res;
80 memset(&hints, 0, sizeof(hints));
81 hints.ai_family = AF_INET6;
82 hints.ai_socktype = SOCK_STREAM;
83 hints.ai_flags = AI_NUMERICHOST;
84 if ((rc = getaddrinfo(CS address, NULL, &hints, &res)) != 0 || res == NULL)
85 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
86 "IP address: %s", address,
87 (rc == 0)? "NULL result returned" : gai_strerror(rc));
88 memcpy(saddr, res->ai_addr, res->ai_addrlen);
93 #endif /* HAVE_IPV6 */
96 /*************************************************
97 * Bind socket to interface and port *
98 *************************************************/
100 /* This function binds a socket to a local interface address and port. For a
101 wildcard IPv6 bind, the address is ":".
105 af AF_INET or AF_INET6 - the socket type
106 address the IP address, in text form
107 port the IP port (host order)
109 Returns: the result of bind()
113 ip_bind(int sock, int af, uschar *address, int port)
116 union sockaddr_46 sin;
117 memset(&sin, 0, sizeof(sin));
119 /* Setup code when using an IPv6 socket. The wildcard address is ":", to
120 ensure an IPv6 socket is used. */
125 if (address[0] == ':' && address[1] == 0)
127 sin.v6.sin6_family = AF_INET6;
128 sin.v6.sin6_addr = in6addr_any;
132 ip_addrinfo(address, &sin.v6); /* Panic-dies on error */
134 sin.v6.sin6_port = htons(port);
135 s_len = sizeof(sin.v6);
138 #else /* HAVE_IPv6 */
139 af = af; /* Avoid compiler warning */
140 #endif /* HAVE_IPV6 */
142 /* Setup code when using IPv4 socket. The wildcard address is "". */
145 sin.v4.sin_family = AF_INET;
146 sin.v4.sin_port = htons(port);
147 s_len = sizeof(sin.v4);
149 sin.v4.sin_addr.s_addr = (S_ADDR_TYPE)INADDR_ANY;
151 sin.v4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CS address);
154 /* Now we can call the bind() function */
156 return bind(sock, (struct sockaddr *)&sin, s_len);
161 /*************************************************
162 * Connect socket to remote host *
163 *************************************************/
165 /* This function connects a socket to a remote address and port. The socket may
166 or may not have previously been bound to a local interface. The socket is not
167 closed, even in cases of error. It is expected that the calling function, which
168 created the socket, will be the one that closes it.
172 af AF_INET6 or AF_INET for the socket type
173 address the remote address, in text form
177 Returns: 0 on success; -1 on failure, with errno set
181 ip_connect(int sock, int af, uschar *address, int port, int timeout)
183 struct sockaddr_in s_in4;
184 struct sockaddr *s_ptr;
185 int s_len, rc, save_errno;
187 /* For an IPv6 address, use an IPv6 sockaddr structure. */
190 struct sockaddr_in6 s_in6;
193 memset(&s_in6, 0, sizeof(s_in6));
194 ip_addrinfo(address, &s_in6); /* Panic-dies on error */
195 s_in6.sin6_port = htons(port);
196 s_ptr = (struct sockaddr *)&s_in6;
197 s_len = sizeof(s_in6);
200 #else /* HAVE_IPV6 */
201 af = af; /* Avoid compiler warning */
202 #endif /* HAVE_IPV6 */
204 /* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with
208 memset(&s_in4, 0, sizeof(s_in4));
209 s_in4.sin_family = AF_INET;
210 s_in4.sin_port = htons(port);
211 s_in4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CS address);
212 s_ptr = (struct sockaddr *)&s_in4;
213 s_len = sizeof(s_in4);
216 /* If no connection timeout is set, just call connect() without setting a
217 timer, thereby allowing the inbuilt OS timeout to operate. */
219 sigalrm_seen = FALSE;
220 if (timeout > 0) alarm(timeout);
221 rc = connect(sock, s_ptr, s_len);
225 /* There is a testing facility for simulating a connection timeout, as I
226 can't think of any other way of doing this. It converts a connection refused
227 into a timeout if the timeout is set to 999999. */
229 if (running_in_test_harness)
231 if (save_errno == ECONNREFUSED && timeout == 999999)
241 if (rc >= 0) return 0;
243 /* A failure whose error code is "Interrupted system call" is in fact
244 an externally applied timeout if the signal handler has been run. */
246 errno = (save_errno == EINTR && sigalrm_seen)? ETIMEDOUT : save_errno;
252 /*************************************************
253 * Set keepalive on a socket *
254 *************************************************/
256 /* Can be called for both incoming and outgoing sockets.
260 address the remote host address, for failure logging
261 torf true for outgoing connection, false for incoming
267 ip_keepalive(int sock, uschar *address, BOOL torf)
270 if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
271 (uschar *)(&fodder), sizeof(fodder)) != 0)
272 log_write(0, LOG_MAIN, "setsockopt(SO_KEEPALIVE) on connection %s %s "
273 "failed: %s", torf? "to":"from", address, strerror(errno));
278 /*************************************************
279 * Receive from a socket with timeout *
280 *************************************************/
282 /* The timeout is implemented using select(), and we loop to cover select()
283 getting interrupted, and the possibility of select() returning with a positive
284 result but no ready descriptor. Is this in fact possible?
289 bufsize the buffer size
292 Returns: > 0 => that much data read
293 <= 0 on error or EOF; errno set - zero for EOF
297 ip_recv(int sock, uschar *buffer, int buffsize, int timeout)
301 int start_recv = time(NULL);
304 /* Wait until the socket is ready */
308 FD_ZERO (&select_inset);
309 FD_SET (sock, &select_inset);
313 DEBUG(D_transport) debug_printf("waiting for data on socket\n");
314 rc = select(sock + 1, (SELECT_ARG2_TYPE *)&select_inset, NULL, NULL, &tv);
316 /* If some interrupt arrived, just retry. We presume this to be rare,
317 but it can happen (e.g. the SIGUSR1 signal sent by exiwhat causes
320 Aug 2004: Somebody set up a cron job that ran exiwhat every 2 minutes, making
321 the interrupt not at all rare. Since the timeout is typically more than 2
322 minutes, the effect was to block the timeout completely. To prevent this
323 happening again, we do an explicit time test. */
325 if (rc < 0 && errno == EINTR)
327 DEBUG(D_transport) debug_printf("EINTR while waiting for socket data\n");
328 if (time(NULL) - start_recv < timeout) continue;
329 DEBUG(D_transport) debug_printf("total wait time exceeds timeout\n");
332 /* Handle a timeout, and treat any other select error as a timeout, including
333 an EINTR when we have been in this loop for longer than timeout. */
341 /* If the socket is ready, break out of the loop. */
343 if (FD_ISSET(sock, &select_inset)) break;
346 /* The socket is ready, read from it (via TLS if it's active). On EOF (i.e.
347 close down of the connection), set errno to zero; otherwise leave it alone. */
350 if (tls_active == sock)
351 rc = tls_read(buffer, buffsize);
354 rc = recv(sock, buffer, buffsize, 0);
356 if (rc > 0) return rc;
357 if (rc == 0) errno = 0;