DNSSEC babystep: dns_use_dnssec & $sender_host_dnssec
[exim.git] / src / src / ip.c
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1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
0a49a7a4 5/* Copyright (c) University of Cambridge 1995 - 2009 */
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6/* See the file NOTICE for conditions of use and distribution. */
7
8/* Functions for doing things with sockets. With the advent of IPv6 this has
9got messier, so that it's worth pulling out the code into separate functions
10that other parts of Exim can call, expecially as there are now several
11different places in the code where sockets are used. */
12
13
14#include "exim.h"
15
16
17/*************************************************
18* Create a socket *
19*************************************************/
20
21/* Socket creation happens in a number of places so it's packaged here for
22convenience.
23
24Arguments:
25 type SOCK_DGRAM or SOCK_STREAM
26 af AF_INET or AF_INET6
27
28Returns: socket number or -1 on failure
29*/
30
31int
32ip_socket(int type, int af)
33{
34int sock = socket(af, type, 0);
35if (sock < 0)
36 log_write(0, LOG_MAIN, "IPv%c socket creation failed: %s",
37 (af == AF_INET6)? '6':'4', strerror(errno));
38return sock;
39}
40
41
42
43
44#if HAVE_IPV6
45/*************************************************
46* Convert printing address to numeric *
47*************************************************/
48
49/* This function converts the textual form of an IP address into a numeric form
50in an appropriate structure in an IPv6 environment. The getaddrinfo() function
51can (apparently) handle more complicated addresses (e.g. those containing
52scopes) than inet_pton() in some environments. We use hints to tell it that the
53input must be a numeric address.
54
55However, apparently some operating systems (or libraries) don't support
56getaddrinfo(), so there is a build-time option to revert to inet_pton() (which
57does not support scopes).
58
59Arguments:
60 address textual form of the address
61 addr where to copy back the answer
62
63Returns: nothing - failure provokes a panic-die
64*/
65
66static void
67ip_addrinfo(uschar *address, struct sockaddr_in6 *saddr)
68{
69#ifdef IPV6_USE_INET_PTON
70
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;
75
76#else
77
78 int rc;
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);
89 freeaddrinfo(res);
90
91#endif
92}
93#endif /* HAVE_IPV6 */
94
95
96/*************************************************
97* Bind socket to interface and port *
98*************************************************/
99
100/* This function binds a socket to a local interface address and port. For a
101wildcard IPv6 bind, the address is ":".
102
103Arguments:
104 sock the socket
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)
108
109Returns: the result of bind()
110*/
111
112int
113ip_bind(int sock, int af, uschar *address, int port)
114{
115int s_len;
116union sockaddr_46 sin;
117memset(&sin, 0, sizeof(sin));
118
119/* Setup code when using an IPv6 socket. The wildcard address is ":", to
120ensure an IPv6 socket is used. */
121
122#if HAVE_IPV6
123if (af == AF_INET6)
124 {
125 if (address[0] == ':' && address[1] == 0)
126 {
127 sin.v6.sin6_family = AF_INET6;
128 sin.v6.sin6_addr = in6addr_any;
129 }
130 else
131 {
132 ip_addrinfo(address, &sin.v6); /* Panic-dies on error */
133 }
134 sin.v6.sin6_port = htons(port);
135 s_len = sizeof(sin.v6);
136 }
137else
138#else /* HAVE_IPv6 */
139af = af; /* Avoid compiler warning */
140#endif /* HAVE_IPV6 */
141
142/* Setup code when using IPv4 socket. The wildcard address is "". */
143
144 {
145 sin.v4.sin_family = AF_INET;
146 sin.v4.sin_port = htons(port);
147 s_len = sizeof(sin.v4);
148 if (address[0] == 0)
149 sin.v4.sin_addr.s_addr = (S_ADDR_TYPE)INADDR_ANY;
150 else
151 sin.v4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CS address);
152 }
153
154/* Now we can call the bind() function */
155
156return bind(sock, (struct sockaddr *)&sin, s_len);
157}
158
159
160
161/*************************************************
162* Connect socket to remote host *
163*************************************************/
164
165/* This function connects a socket to a remote address and port. The socket may
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166or may not have previously been bound to a local interface. The socket is not
167closed, even in cases of error. It is expected that the calling function, which
168created the socket, will be the one that closes it.
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169
170Arguments:
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
177Returns: 0 on success; -1 on failure, with errno set
178*/
179
180int
181ip_connect(int sock, int af, uschar *address, int port, int timeout)
182{
183struct sockaddr_in s_in4;
184struct sockaddr *s_ptr;
185int s_len, rc, save_errno;
186
187/* For an IPv6 address, use an IPv6 sockaddr structure. */
188
189#if HAVE_IPV6
190struct sockaddr_in6 s_in6;
191if (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 }
199else
200#else /* HAVE_IPV6 */
201af = af; /* Avoid compiler warning */
202#endif /* HAVE_IPV6 */
203
204/* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with
205IPv6 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
217timer, thereby allowing the inbuilt OS timeout to operate. */
218
219sigalrm_seen = FALSE;
220if (timeout > 0) alarm(timeout);
221rc = connect(sock, s_ptr, s_len);
222save_errno = errno;
223alarm(0);
224
225/* There is a testing facility for simulating a connection timeout, as I
226can't think of any other way of doing this. It converts a connection refused
75e0e026 227into a timeout if the timeout is set to 999999. */
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228
229if (running_in_test_harness)
230 {
75e0e026 231 if (save_errno == ECONNREFUSED && timeout == 999999)
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232 {
233 rc = -1;
234 save_errno = EINTR;
235 sigalrm_seen = TRUE;
236 }
237 }
238
239/* Success */
240
241if (rc >= 0) return 0;
242
243/* A failure whose error code is "Interrupted system call" is in fact
244an externally applied timeout if the signal handler has been run. */
245
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246errno = (save_errno == EINTR && sigalrm_seen)? ETIMEDOUT : save_errno;
247return -1;
248}
249
250
251
252/*************************************************
253* Set keepalive on a socket *
254*************************************************/
255
256/* Can be called for both incoming and outgoing sockets.
257
258Arguments:
259 sock the socket
260 address the remote host address, for failure logging
261 torf true for outgoing connection, false for incoming
262
263Returns: nothing
264*/
265
266void
267ip_keepalive(int sock, uschar *address, BOOL torf)
268{
269int fodder = 1;
270if (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));
274}
275
276
277
278/*************************************************
279* Receive from a socket with timeout *
280*************************************************/
281
282/* The timeout is implemented using select(), and we loop to cover select()
283getting interrupted, and the possibility of select() returning with a positive
284result but no ready descriptor. Is this in fact possible?
285
286Arguments:
287 sock the socket
288 buffer to read into
289 bufsize the buffer size
290 timeout the timeout
291
292Returns: > 0 => that much data read
293 <= 0 on error or EOF; errno set - zero for EOF
294*/
295
296int
297ip_recv(int sock, uschar *buffer, int buffsize, int timeout)
298{
299fd_set select_inset;
300struct timeval tv;
301int start_recv = time(NULL);
302int rc;
303
304/* Wait until the socket is ready */
305
306for (;;)
307 {
308 FD_ZERO (&select_inset);
309 FD_SET (sock, &select_inset);
310 tv.tv_sec = timeout;
311 tv.tv_usec = 0;
312
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);
315
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
318 select() to exit).
319
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. */
324
325 if (rc < 0 && errno == EINTR)
326 {
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");
330 }
331
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. */
334
335 if (rc <= 0)
336 {
337 errno = ETIMEDOUT;
338 return -1;
339 }
340
341 /* If the socket is ready, break out of the loop. */
342
343 if (FD_ISSET(sock, &select_inset)) break;
344 }
345
346/* The socket is ready, read from it (via TLS if it's active). On EOF (i.e.
347close down of the connection), set errno to zero; otherwise leave it alone. */
348
349#ifdef SUPPORT_TLS
350if (tls_active == sock)
351 rc = tls_read(buffer, buffsize);
352else
353#endif
354 rc = recv(sock, buffer, buffsize, 0);
355
356if (rc > 0) return rc;
357if (rc == 0) errno = 0;
358return -1;
359}
360
361
362/* End of ip.c */