1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2017 */
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, especially 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(const uschar *address, struct sockaddr_in6 *saddr)
69 #ifdef IPV6_USE_INET_PTON
71 if (inet_pton(AF_INET6, CCS 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(CCS 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 *************************************************/
101 ip_addr(void * sin_, int af, const uschar * address, int port)
103 union sockaddr_46 * sin = sin_;
104 memset(sin, 0, sizeof(*sin));
106 /* Setup code when using an IPv6 socket. The wildcard address is ":", to
107 ensure an IPv6 socket is used. */
112 if (address[0] == ':' && address[1] == 0)
114 sin->v6.sin6_family = AF_INET6;
115 sin->v6.sin6_addr = in6addr_any;
118 ip_addrinfo(address, &sin->v6); /* Panic-dies on error */
119 sin->v6.sin6_port = htons(port);
120 return sizeof(sin->v6);
123 #else /* HAVE_IPv6 */
124 af = af; /* Avoid compiler warning */
125 #endif /* HAVE_IPV6 */
127 /* Setup code when using IPv4 socket. The wildcard address is "". */
130 sin->v4.sin_family = AF_INET;
131 sin->v4.sin_port = htons(port);
132 sin->v4.sin_addr.s_addr = address[0] == 0
133 ? (S_ADDR_TYPE)INADDR_ANY
134 : (S_ADDR_TYPE)inet_addr(CS address);
135 return sizeof(sin->v4);
141 /* This function binds a socket to a local interface address and port. For a
142 wildcard IPv6 bind, the address is ":".
146 af AF_INET or AF_INET6 - the socket type
147 address the IP address, in text form
148 port the IP port (host order)
150 Returns: the result of bind()
154 ip_bind(int sock, int af, uschar *address, int port)
156 union sockaddr_46 sin;
157 int s_len = ip_addr(&sin, af, address, port);
158 return bind(sock, (struct sockaddr *)&sin, s_len);
163 /*************************************************
164 * Connect socket to remote host *
165 *************************************************/
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. The socket is not
169 closed, even in cases of error. It is expected that the calling function, which
170 created the socket, will be the one that closes it.
174 af AF_INET6 or AF_INET for the socket type
175 address the remote address, in text form
177 timeout a timeout (zero for indefinite timeout)
178 fastopen TRUE iff TCP_FASTOPEN can be used
180 Returns: 0 on success; -1 on failure, with errno set
184 ip_connect(int sock, int af, const uschar *address, int port, int timeout,
187 struct sockaddr_in s_in4;
188 struct sockaddr *s_ptr;
189 int s_len, rc, save_errno;
191 /* For an IPv6 address, use an IPv6 sockaddr structure. */
194 struct sockaddr_in6 s_in6;
197 memset(&s_in6, 0, sizeof(s_in6));
198 ip_addrinfo(address, &s_in6); /* Panic-dies on error */
199 s_in6.sin6_port = htons(port);
200 s_ptr = (struct sockaddr *)&s_in6;
201 s_len = sizeof(s_in6);
204 #else /* HAVE_IPV6 */
205 af = af; /* Avoid compiler warning */
206 #endif /* HAVE_IPV6 */
208 /* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with
212 memset(&s_in4, 0, sizeof(s_in4));
213 s_in4.sin_family = AF_INET;
214 s_in4.sin_port = htons(port);
215 s_in4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CCS address);
216 s_ptr = (struct sockaddr *)&s_in4;
217 s_len = sizeof(s_in4);
220 /* If no connection timeout is set, just call connect() without setting a
221 timer, thereby allowing the inbuilt OS timeout to operate. */
223 callout_address = string_sprintf("[%s]:%d", address, port);
224 sigalrm_seen = FALSE;
225 if (timeout > 0) alarm(timeout);
227 #if defined(TCP_FASTOPEN) && defined(MSG_FASTOPEN)
228 /* TCP Fast Open, if the system has a cookie from a previous call to
229 this peer, can send data in the SYN packet. The peer can send data
230 before it gets our ACK of its SYN,ACK - the latter is useful for
231 the SMTP banner. Is there any usage where the former might be?
232 We might extend the ip_connect() args for data if so. For now,
233 connect in FASTOPEN mode but with zero data.
238 if ((rc = sendto(sock, NULL, 0, MSG_FASTOPEN | MSG_DONTWAIT, s_ptr, s_len)) < 0)
239 if (errno == EINPROGRESS) /* the expected case */
241 else if(errno == EOPNOTSUPP)
244 debug_printf("Tried TCP Fast Open but apparently not enabled by sysctl\n");
245 rc = connect(sock, s_ptr, s_len);
250 rc = connect(sock, s_ptr, s_len);
255 /* There is a testing facility for simulating a connection timeout, as I
256 can't think of any other way of doing this. It converts a connection refused
257 into a timeout if the timeout is set to 999999. */
259 if (running_in_test_harness && save_errno == ECONNREFUSED && timeout == 999999)
271 /* A failure whose error code is "Interrupted system call" is in fact
272 an externally applied timeout if the signal handler has been run. */
274 errno = save_errno == EINTR && sigalrm_seen ? ETIMEDOUT : save_errno;
280 /*************************************************
281 * Create connected socket to remote host *
282 *************************************************/
284 /* Create a socket and connect to host (name or number, ipv6 ok)
285 at one of port-range.
288 type SOCK_DGRAM or SOCK_STREAM
289 af AF_INET6 or AF_INET for the socket type
290 address the remote address, in text form
291 portlo,porthi the remote port range
293 connhost if not NULL, host_item filled in with connection details
294 errstr pointer for allocated string on error
297 socket fd, or -1 on failure (having allocated an error string)
300 ip_connectedsocket(int type, const uschar * hostname, int portlo, int porthi,
301 int timeout, host_item * connhost, uschar ** errstr)
306 int af = 0, fd, fd4 = -1, fd6 = -1;
307 BOOL fastopen = tcp_fastopen_ok && type == SOCK_STREAM;
310 shost.address = NULL;
314 namelen = Ustrlen(hostname);
316 /* Anything enclosed in [] must be an IP address. */
318 if (hostname[0] == '[' &&
319 hostname[namelen - 1] == ']')
321 uschar * host = string_copyn(hostname+1, namelen-2);
322 if (string_is_ip_address(host, NULL) == 0)
324 *errstr = string_sprintf("malformed IP address \"%s\"", hostname);
327 shost.name = shost.address = host;
330 /* Otherwise check for an unadorned IP address */
332 else if (string_is_ip_address(hostname, NULL) != 0)
333 shost.name = shost.address = string_copyn(hostname, namelen);
335 /* Otherwise lookup IP address(es) from the name */
339 shost.name = string_copyn(hostname, namelen);
340 if (host_find_byname(&shost, NULL, HOST_FIND_QUALIFY_SINGLE,
341 NULL, FALSE) != HOST_FOUND)
343 *errstr = string_sprintf("no IP address found for host %s", shost.name);
348 /* Try to connect to the server - test each IP till one works */
350 for (h = &shost; h; h = h->next)
352 fd = Ustrchr(h->address, ':') != 0
353 ? fd6 < 0 ? (fd6 = ip_socket(type, af = AF_INET6)) : fd6
354 : fd4 < 0 ? (fd4 = ip_socket(type, af = AF_INET )) : fd4;
358 *errstr = string_sprintf("failed to create socket: %s", strerror(errno));
362 for(port = portlo; port <= porthi; port++)
363 if (ip_connect(fd, af, h->address, port, timeout, fastopen) == 0)
365 if (fd != fd6) close(fd6);
366 if (fd != fd4) close(fd4);
371 connhost->next = NULL;
377 *errstr = string_sprintf("failed to connect to any address for %s: %s",
378 hostname, strerror(errno));
381 close(fd4); close(fd6); return -1;
386 ip_tcpsocket(const uschar * hostport, uschar ** errstr, int tmo)
389 uschar hostname[256];
390 unsigned int portlow, porthigh;
392 /* extract host and port part */
393 scan = sscanf(CS hostport, "%255s %u-%u", hostname, &portlow, &porthigh);
398 *errstr = string_sprintf("invalid socket '%s'", hostport);
404 return ip_connectedsocket(SOCK_STREAM, hostname, portlow, porthigh,
409 ip_unixsocket(const uschar * path, uschar ** errstr)
412 struct sockaddr_un server;
414 if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
416 *errstr = US"can't open UNIX socket.";
420 callout_address = string_copy(path);
421 server.sun_family = AF_UNIX;
422 Ustrncpy(server.sun_path, path, sizeof(server.sun_path)-1);
423 server.sun_path[sizeof(server.sun_path)-1] = '\0';
424 if (connect(sock, (struct sockaddr *) &server, sizeof(server)) < 0)
428 *errstr = string_sprintf("unable to connect to UNIX socket (%s): %s",
429 path, strerror(err));
436 ip_streamsocket(const uschar * spec, uschar ** errstr, int tmo)
439 ? ip_unixsocket(spec, errstr) : ip_tcpsocket(spec, errstr, tmo);
442 /*************************************************
443 * Set keepalive on a socket *
444 *************************************************/
446 /* Can be called for both incoming and outgoing sockets.
450 address the remote host address, for failure logging
451 torf true for outgoing connection, false for incoming
457 ip_keepalive(int sock, const uschar *address, BOOL torf)
460 if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
461 US (&fodder), sizeof(fodder)) != 0)
462 log_write(0, LOG_MAIN, "setsockopt(SO_KEEPALIVE) on connection %s %s "
463 "failed: %s", torf? "to":"from", address, strerror(errno));
468 /*************************************************
469 * Receive from a socket with timeout *
470 *************************************************/
474 fd the file descriptor
475 timeout the timeout, seconds
476 Returns: TRUE => ready for i/o
477 FALSE => timed out, or other error
480 fd_ready(int fd, int timeout)
483 time_t start_recv = time(NULL);
484 int time_left = timeout;
492 /* Wait until the socket is ready */
496 struct timeval tv = { .tv_sec = time_left, .tv_usec = 0 };
497 FD_ZERO (&select_inset);
498 FD_SET (fd, &select_inset);
500 /*DEBUG(D_transport) debug_printf("waiting for data on fd\n");*/
501 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&select_inset, NULL, NULL, &tv);
503 /* If some interrupt arrived, just retry. We presume this to be rare,
504 but it can happen (e.g. the SIGUSR1 signal sent by exiwhat causes
507 Aug 2004: Somebody set up a cron job that ran exiwhat every 2 minutes, making
508 the interrupt not at all rare. Since the timeout is typically more than 2
509 minutes, the effect was to block the timeout completely. To prevent this
510 happening again, we do an explicit time test and adjust the timeout
513 if (rc < 0 && errno == EINTR)
515 DEBUG(D_transport) debug_printf("EINTR while waiting for socket data\n");
517 /* Watch out, 'continue' jumps to the condition, not to the loops top */
518 time_left = timeout - (time(NULL) - start_recv);
519 if (time_left > 0) continue;
528 /* Checking the FD_ISSET is not enough, if we're interrupted, the
529 select_inset may still contain the 'input'. */
531 while (rc < 0 || !FD_ISSET(fd, &select_inset));
535 /* The timeout is implemented using select(), and we loop to cover select()
536 getting interrupted, and the possibility of select() returning with a positive
537 result but no ready descriptor. Is this in fact possible?
542 bufsize the buffer size
545 Returns: > 0 => that much data read
546 <= 0 on error or EOF; errno set - zero for EOF
550 ip_recv(int sock, uschar *buffer, int buffsize, int timeout)
554 if (!fd_ready(sock, timeout))
557 /* The socket is ready, read from it (via TLS if it's active). On EOF (i.e.
558 close down of the connection), set errno to zero; otherwise leave it alone. */
561 if (tls_out.active == sock)
562 rc = tls_read(FALSE, buffer, buffsize);
563 else if (tls_in.active == sock)
564 rc = tls_read(TRUE, buffer, buffsize);
567 rc = recv(sock, buffer, buffsize, 0);
569 if (rc > 0) return rc;
570 if (rc == 0) errno = 0;
577 /*************************************************
578 * Lookup address family of potential socket *
579 *************************************************/
581 /* Given a file-descriptor, check to see if it's a socket and, if so,
582 return the address family; detects IPv4 vs IPv6. If not a socket then
585 The value 0 is typically AF_UNSPEC, which should not be seen on a connected
586 fd. If the return is -1, the errno will be from getsockname(); probably
587 ENOTSOCK or ECONNRESET.
589 Arguments: socket-or-not fd
590 Returns: address family or -1
594 ip_get_address_family(int fd)
596 struct sockaddr_storage ss;
597 socklen_t sslen = sizeof(ss);
599 if (getsockname(fd, (struct sockaddr *) &ss, &sslen) < 0)
602 return (int) ss.ss_family;
608 /*************************************************
609 * Lookup DSCP settings for a socket *
610 *************************************************/
612 struct dscp_name_tableentry {
616 /* Keep both of these tables sorted! */
617 static struct dscp_name_tableentry dscp_table[] = {
618 #ifdef IPTOS_DSCP_AF11
619 { CUS"af11", IPTOS_DSCP_AF11 },
620 { CUS"af12", IPTOS_DSCP_AF12 },
621 { CUS"af13", IPTOS_DSCP_AF13 },
622 { CUS"af21", IPTOS_DSCP_AF21 },
623 { CUS"af22", IPTOS_DSCP_AF22 },
624 { CUS"af23", IPTOS_DSCP_AF23 },
625 { CUS"af31", IPTOS_DSCP_AF31 },
626 { CUS"af32", IPTOS_DSCP_AF32 },
627 { CUS"af33", IPTOS_DSCP_AF33 },
628 { CUS"af41", IPTOS_DSCP_AF41 },
629 { CUS"af42", IPTOS_DSCP_AF42 },
630 { CUS"af43", IPTOS_DSCP_AF43 },
631 { CUS"ef", IPTOS_DSCP_EF },
634 { CUS"lowcost", IPTOS_LOWCOST },
636 { CUS"lowdelay", IPTOS_LOWDELAY },
638 { CUS"mincost", IPTOS_MINCOST },
640 { CUS"reliability", IPTOS_RELIABILITY },
641 { CUS"throughput", IPTOS_THROUGHPUT }
643 static int dscp_table_size =
644 sizeof(dscp_table) / sizeof(struct dscp_name_tableentry);
646 /* DSCP values change by protocol family, and so do the options used for
647 setsockopt(); this utility does all the lookups. It takes an unexpanded
648 option string, expands it, strips off affix whitespace, then checks if it's
649 a number. If all of what's left is a number, then that's how the option will
650 be parsed and success/failure is a range check. If it's not all a number,
651 then it must be a supported keyword.
654 dscp_name a string, so far unvalidated
655 af address_family in use
656 level setsockopt level to use
657 optname setsockopt name to use
658 dscp_value value for dscp_name
660 Returns: TRUE if okay to setsockopt(), else FALSE
662 *level and *optname may be set even if FALSE is returned
666 dscp_lookup(const uschar *dscp_name, int af,
667 int *level, int *optname, int *dscp_value)
669 uschar *dscp_lookup, *p;
678 #if HAVE_IPV6 && defined(IPV6_TCLASS)
679 else if (af == AF_INET6)
681 *level = IPPROTO_IPV6;
682 *optname = IPV6_TCLASS;
688 debug_printf("Unhandled address family %d in dscp_lookup()\n", af);
694 debug_printf("[empty DSCP]\n");
697 dscp_lookup = expand_string(US dscp_name);
698 if (dscp_lookup == NULL || *dscp_lookup == '\0')
701 p = dscp_lookup + Ustrlen(dscp_lookup) - 1;
702 while (isspace(*p)) *p-- = '\0';
703 while (isspace(*dscp_lookup) && dscp_lookup < p) dscp_lookup++;
704 if (*dscp_lookup == '\0')
707 rawlong = Ustrtol(dscp_lookup, &p, 0);
708 if (p != dscp_lookup && *p == '\0')
710 /* We have six bits available, which will end up shifted to fit in 0xFC mask.
711 RFC 2597 defines the values unshifted. */
712 if (rawlong < 0 || rawlong > 0x3F)
715 debug_printf("DSCP value %ld out of range, ignored.\n", rawlong);
718 *dscp_value = rawlong << 2;
723 last = dscp_table_size;
726 int middle = (first + last)/2;
727 int c = Ustrcmp(dscp_lookup, dscp_table[middle].name);
730 *dscp_value = dscp_table[middle].value;
742 dscp_list_to_stream(FILE *stream)
745 for (i=0; i < dscp_table_size; ++i)
746 fprintf(stream, "%s\n", dscp_table[i].name);