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[exim.git] / src / src / ip.c
1 /* $Cambridge: exim/src/src/ip.c,v 1.1 2004/10/07 10:39:01 ph10 Exp $ */
2
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
6
7 /* Copyright (c) University of Cambridge 1995 - 2004 */
8 /* See the file NOTICE for conditions of use and distribution. */
9
10 /* Functions for doing things with sockets. With the advent of IPv6 this has
11 got messier, so that it's worth pulling out the code into separate functions
12 that other parts of Exim can call, expecially as there are now several
13 different places in the code where sockets are used. */
14
15
16 #include "exim.h"
17
18
19 /*************************************************
20 * Create a socket *
21 *************************************************/
22
23 /* Socket creation happens in a number of places so it's packaged here for
24 convenience.
25
26 Arguments:
27 type SOCK_DGRAM or SOCK_STREAM
28 af AF_INET or AF_INET6
29
30 Returns: socket number or -1 on failure
31 */
32
33 int
34 ip_socket(int type, int af)
35 {
36 int sock = socket(af, type, 0);
37 if (sock < 0)
38 log_write(0, LOG_MAIN, "IPv%c socket creation failed: %s",
39 (af == AF_INET6)? '6':'4', strerror(errno));
40 return sock;
41 }
42
43
44
45
46 #if HAVE_IPV6
47 /*************************************************
48 * Convert printing address to numeric *
49 *************************************************/
50
51 /* This function converts the textual form of an IP address into a numeric form
52 in an appropriate structure in an IPv6 environment. The getaddrinfo() function
53 can (apparently) handle more complicated addresses (e.g. those containing
54 scopes) than inet_pton() in some environments. We use hints to tell it that the
55 input must be a numeric address.
56
57 However, apparently some operating systems (or libraries) don't support
58 getaddrinfo(), so there is a build-time option to revert to inet_pton() (which
59 does not support scopes).
60
61 Arguments:
62 address textual form of the address
63 addr where to copy back the answer
64
65 Returns: nothing - failure provokes a panic-die
66 */
67
68 static void
69 ip_addrinfo(uschar *address, struct sockaddr_in6 *saddr)
70 {
71 #ifdef IPV6_USE_INET_PTON
72
73 if (inet_pton(AF_INET6, CS address, &saddr->sin6_addr) != 1)
74 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
75 "IP address", address);
76 saddr->sin6_family = AF_INET6;
77
78 #else
79
80 int rc;
81 struct addrinfo hints, *res;
82 memset(&hints, 0, sizeof(hints));
83 hints.ai_family = AF_INET6;
84 hints.ai_socktype = SOCK_STREAM;
85 hints.ai_flags = AI_NUMERICHOST;
86 if ((rc = getaddrinfo(CS address, NULL, &hints, &res)) != 0 || res == NULL)
87 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
88 "IP address: %s", address,
89 (rc == 0)? "NULL result returned" : gai_strerror(rc));
90 memcpy(saddr, res->ai_addr, res->ai_addrlen);
91 freeaddrinfo(res);
92
93 #endif
94 }
95 #endif /* HAVE_IPV6 */
96
97
98 /*************************************************
99 * Bind socket to interface and port *
100 *************************************************/
101
102 /* This function binds a socket to a local interface address and port. For a
103 wildcard IPv6 bind, the address is ":".
104
105 Arguments:
106 sock the socket
107 af AF_INET or AF_INET6 - the socket type
108 address the IP address, in text form
109 port the IP port (host order)
110
111 Returns: the result of bind()
112 */
113
114 int
115 ip_bind(int sock, int af, uschar *address, int port)
116 {
117 int s_len;
118 union sockaddr_46 sin;
119 memset(&sin, 0, sizeof(sin));
120
121 /* Setup code when using an IPv6 socket. The wildcard address is ":", to
122 ensure an IPv6 socket is used. */
123
124 #if HAVE_IPV6
125 if (af == AF_INET6)
126 {
127 if (address[0] == ':' && address[1] == 0)
128 {
129 sin.v6.sin6_family = AF_INET6;
130 sin.v6.sin6_addr = in6addr_any;
131 }
132 else
133 {
134 ip_addrinfo(address, &sin.v6); /* Panic-dies on error */
135 }
136 sin.v6.sin6_port = htons(port);
137 s_len = sizeof(sin.v6);
138 }
139 else
140 #else /* HAVE_IPv6 */
141 af = af; /* Avoid compiler warning */
142 #endif /* HAVE_IPV6 */
143
144 /* Setup code when using IPv4 socket. The wildcard address is "". */
145
146 {
147 sin.v4.sin_family = AF_INET;
148 sin.v4.sin_port = htons(port);
149 s_len = sizeof(sin.v4);
150 if (address[0] == 0)
151 sin.v4.sin_addr.s_addr = (S_ADDR_TYPE)INADDR_ANY;
152 else
153 sin.v4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CS address);
154 }
155
156 /* Now we can call the bind() function */
157
158 return bind(sock, (struct sockaddr *)&sin, s_len);
159 }
160
161
162
163 /*************************************************
164 * Connect socket to remote host *
165 *************************************************/
166
167 /* This function connects a socket to a remote address and port. The socket may
168 or may not have previously been bound to a local interface.
169
170 Arguments:
171 sock the socket
172 af AF_INET6 or AF_INET for the socket type
173 address the remote address, in text form
174 port the remote port
175 timeout a timeout
176
177 Returns: 0 on success; -1 on failure, with errno set
178 */
179
180 int
181 ip_connect(int sock, int af, uschar *address, int port, int timeout)
182 {
183 struct sockaddr_in s_in4;
184 struct sockaddr *s_ptr;
185 int s_len, rc, save_errno;
186
187 /* For an IPv6 address, use an IPv6 sockaddr structure. */
188
189 #if HAVE_IPV6
190 struct sockaddr_in6 s_in6;
191 if (af == AF_INET6)
192 {
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);
198 }
199 else
200 #else /* HAVE_IPV6 */
201 af = af; /* Avoid compiler warning */
202 #endif /* HAVE_IPV6 */
203
204 /* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with
205 IPv6 support. */
206
207 {
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);
214 }
215
216 /* If no connection timeout is set, just call connect() without setting a
217 timer, thereby allowing the inbuilt OS timeout to operate. */
218
219 sigalrm_seen = FALSE;
220 if (timeout > 0) alarm(timeout);
221 rc = connect(sock, s_ptr, s_len);
222 save_errno = errno;
223 alarm(0);
224
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.
228
229 I had to add a second fudge to keep the tests working. Attempts to connect to
230 10.x.x.x are expected to timeout, but sometimes they now give "No route to
231 host". */
232
233 if (running_in_test_harness)
234 {
235 if ((save_errno == ECONNREFUSED && timeout == 999999) ||
236 (save_errno == EHOSTUNREACH && timeout > 0 &&
237 Ustrncmp(address, "10.", 3) == 0))
238 {
239 rc = -1;
240 save_errno = EINTR;
241 sigalrm_seen = TRUE;
242 }
243 }
244
245 /* Success */
246
247 if (rc >= 0) return 0;
248
249 /* A failure whose error code is "Interrupted system call" is in fact
250 an externally applied timeout if the signal handler has been run. */
251
252 close(sock);
253 errno = (save_errno == EINTR && sigalrm_seen)? ETIMEDOUT : save_errno;
254 return -1;
255 }
256
257
258
259 /*************************************************
260 * Set keepalive on a socket *
261 *************************************************/
262
263 /* Can be called for both incoming and outgoing sockets.
264
265 Arguments:
266 sock the socket
267 address the remote host address, for failure logging
268 torf true for outgoing connection, false for incoming
269
270 Returns: nothing
271 */
272
273 void
274 ip_keepalive(int sock, uschar *address, BOOL torf)
275 {
276 int fodder = 1;
277 if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
278 (uschar *)(&fodder), sizeof(fodder)) != 0)
279 log_write(0, LOG_MAIN, "setsockopt(SO_KEEPALIVE) on connection %s %s "
280 "failed: %s", torf? "to":"from", address, strerror(errno));
281 }
282
283
284
285 /*************************************************
286 * Receive from a socket with timeout *
287 *************************************************/
288
289 /* The timeout is implemented using select(), and we loop to cover select()
290 getting interrupted, and the possibility of select() returning with a positive
291 result but no ready descriptor. Is this in fact possible?
292
293 Arguments:
294 sock the socket
295 buffer to read into
296 bufsize the buffer size
297 timeout the timeout
298
299 Returns: > 0 => that much data read
300 <= 0 on error or EOF; errno set - zero for EOF
301 */
302
303 int
304 ip_recv(int sock, uschar *buffer, int buffsize, int timeout)
305 {
306 fd_set select_inset;
307 struct timeval tv;
308 int start_recv = time(NULL);
309 int rc;
310
311 /* Wait until the socket is ready */
312
313 for (;;)
314 {
315 FD_ZERO (&select_inset);
316 FD_SET (sock, &select_inset);
317 tv.tv_sec = timeout;
318 tv.tv_usec = 0;
319
320 DEBUG(D_transport) debug_printf("waiting for data on socket\n");
321 rc = select(sock + 1, (SELECT_ARG2_TYPE *)&select_inset, NULL, NULL, &tv);
322
323 /* If some interrupt arrived, just retry. We presume this to be rare,
324 but it can happen (e.g. the SIGUSR1 signal sent by exiwhat causes
325 select() to exit).
326
327 Aug 2004: Somebody set up a cron job that ran exiwhat every 2 minutes, making
328 the interrupt not at all rare. Since the timeout is typically more than 2
329 minutes, the effect was to block the timeout completely. To prevent this
330 happening again, we do an explicit time test. */
331
332 if (rc < 0 && errno == EINTR)
333 {
334 DEBUG(D_transport) debug_printf("EINTR while waiting for socket data\n");
335 if (time(NULL) - start_recv < timeout) continue;
336 DEBUG(D_transport) debug_printf("total wait time exceeds timeout\n");
337 }
338
339 /* Handle a timeout, and treat any other select error as a timeout, including
340 an EINTR when we have been in this loop for longer than timeout. */
341
342 if (rc <= 0)
343 {
344 errno = ETIMEDOUT;
345 return -1;
346 }
347
348 /* If the socket is ready, break out of the loop. */
349
350 if (FD_ISSET(sock, &select_inset)) break;
351 }
352
353 /* The socket is ready, read from it (via TLS if it's active). On EOF (i.e.
354 close down of the connection), set errno to zero; otherwise leave it alone. */
355
356 #ifdef SUPPORT_TLS
357 if (tls_active == sock)
358 rc = tls_read(buffer, buffsize);
359 else
360 #endif
361 rc = recv(sock, buffer, buffsize, 0);
362
363 if (rc > 0) return rc;
364 if (rc == 0) errno = 0;
365 return -1;
366 }
367
368
369 /* End of ip.c */