server: Add --http-listen-address and --dccp-listen-address.
[paraslash.git] / net.c
1 /* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
2
3 /** \file net.c Networking-related helper functions. */
4
5 #include "para.h"
6
7 #include <netinet/in.h>
8 #include <arpa/inet.h>
9 #include <sys/un.h>
10 #include <sys/types.h>
11 #include <sys/socket.h>
12 #include <netdb.h>
13
14 /* At least NetBSD needs these. */
15 #ifndef AI_V4MAPPED
16 #define AI_V4MAPPED 0
17 #endif
18 #ifndef AI_ALL
19 #define AI_ALL 0
20 #endif
21 #ifndef AI_ADDRCONFIG
22 #define AI_ADDRCONFIG 0
23 #endif
24
25 #include <regex.h>
26
27 #include "error.h"
28 #include "net.h"
29 #include "string.h"
30 #include "list.h"
31 #include "fd.h"
32
33 /**
34 * Parse and validate IPv4 address/netmask string.
35 *
36 * \param cidr Address in CIDR notation
37 * \param addr Copy of the IPv4 address part of \a cidr
38 * \param addrlen Size of \a addr in bytes
39 * \param netmask Value of the netmask part in \a cidr or the
40 * default of 32 if not specified.
41 *
42 * \return Pointer to \a addr if successful, NULL on error.
43 * \sa RFC 4632.
44 */
45 char *parse_cidr(const char *cidr,
46 char *addr, ssize_t addrlen,
47 int32_t *netmask)
48 {
49 const char *o = cidr;
50 char *c = addr, *end = c + (addrlen - 1);
51
52 *netmask = 0x20;
53
54 if (cidr == NULL || addrlen < 1)
55 goto failed;
56
57 for (o = cidr; (*c = *o == '/'? '\0' : *o); c++, o++)
58 if (c == end)
59 goto failed;
60
61 if (*o == '/')
62 if (para_atoi32(++o, netmask) < 0 ||
63 *netmask < 0 || *netmask > 0x20)
64 goto failed;
65
66 if (is_valid_ipv4_address(addr))
67 return addr;
68 failed:
69 *addr = '\0';
70 return NULL;
71 }
72
73
74 /**
75 * Match string as a candidate IPv4 address.
76 *
77 * \param address The string to match.
78 * \return True if \a address has "dot-quad" format.
79 */
80 static bool is_v4_dot_quad(const char *address)
81 {
82 bool result;
83 regex_t r;
84
85 assert(para_regcomp(&r, "^([0-9]+\\.){3}[0-9]+$",
86 REG_EXTENDED | REG_NOSUB) >= 0);
87 result = regexec(&r, address, 0, NULL, 0) == 0;
88 regfree(&r);
89 return result;
90 }
91
92 /**
93 * Perform basic syntax checking on the host-part of an URL:
94 *
95 * - Since ':' is invalid in IPv4 addresses and DNS names, the
96 * presence of ':' causes interpretation as IPv6 address;
97 * - next the first-match-wins algorithm from RFC 3986 is applied;
98 * - else the string is considered as DNS name, to be resolved later.
99 *
100 * \param host The host string to check.
101 * \return True if \a host passes the syntax checks.
102 *
103 * \sa RFC 3986, 3.2.2; RFC 1123, 2.1; RFC 1034, 3.5.
104 */
105 static bool host_string_ok(const char *host)
106 {
107 if (host == NULL || *host == '\0')
108 return false;
109 if (strchr(host, ':') != NULL)
110 return is_valid_ipv6_address(host);
111 if (is_v4_dot_quad(host))
112 return is_valid_ipv4_address(host);
113 return true;
114 }
115
116 /**
117 * Parse and validate URL string.
118 *
119 * The URL syntax is loosely based on RFC 3986, supporting one of
120 * - "["host"]"[:port] for native IPv6 addresses and
121 * - host[:port] for IPv4 hostnames and DNS names.
122 *
123 * Native IPv6 addresses must be enclosed in square brackets, since
124 * otherwise there is an ambiguity with the port separator `:'.
125 * The 'port' part is always considered to be a number; if absent,
126 * it is set to -1, to indicate that a default port is to be used.
127 *
128 * The following are valid examples:
129 * - 10.10.1.1
130 * - 10.10.1.2:8000
131 * - localhost
132 * - localhost:8001
133 * - [::1]:8000
134 * - [badc0de::1]
135 *
136 * \param url The URL string to take apart.
137 * \param host To return the copied host part of \a url.
138 * \param hostlen The maximum length of \a host.
139 * \param port To return the port number (if any) of \a url.
140 *
141 * \return Pointer to \a host, or \p NULL if failed. If \p NULL is returned,
142 * \a host and \a port are undefined. If no port number was present in \a url,
143 * \a port is set to -1.
144 *
145 * \sa RFC 3986, 3.2.2/3.2.3.
146 */
147 char *parse_url(const char *url,
148 char *host, ssize_t hostlen,
149 int32_t *port)
150 {
151 const char *o = url;
152 char *c = host, *end = c + (hostlen - 1);
153
154 *port = -1;
155
156 if (o == NULL || hostlen < 1)
157 goto failed;
158
159 if (*o == '[') {
160 for (++o; (*c = *o == ']' ? '\0' : *o); c++, o++)
161 if (c == end)
162 goto failed;
163
164 if (*o++ != ']' || (*o != '\0' && *o != ':'))
165 goto failed;
166 } else {
167 for (; (*c = *o == ':'? '\0' : *o); c++, o++) {
168 if (c == end && o[1])
169 goto failed;
170 }
171 }
172
173 if (*o == ':')
174 if (para_atoi32(++o, port) < 0 || *port < 0 || *port > 0xffff)
175 goto failed;
176 if (host_string_ok(host))
177 return host;
178 failed:
179 *host = '\0';
180 return NULL;
181 }
182
183 /**
184 * Pretty-print a host/port pair.
185 *
186 * \param url NULL, or any string accepted by \ref parse_url().
187 * \param default_port Applies if url has no port.
188 *
189 * If the url argument is NULL, the function returns the string
190 * 0.0.0.0:default_port. Otherwise it calls \ref parse_url() to check the
191 * syntax of the input string given by url. On errors the string "?" is
192 * returned. Otherwise, if url contains a port, a copy of url is returned. If
193 * no port was supplied, a colon and the default port are appended to url.
194 *
195 * \return In all cases the returned string is a allocated with malloc(3) and
196 * has to be freed by the caller.
197 */
198 char *format_url(const char *url, int default_port)
199 {
200 char host[MAX_HOSTLEN];
201 int url_port;
202
203 if (!url)
204 return make_message("0.0.0.0:%d", default_port);
205 if (!parse_url(url, host, sizeof(host), &url_port))
206 return make_message("?");
207 if (url_port < 0)
208 return make_message("%s:%d", url, default_port);
209 else
210 return para_strdup(url);
211 }
212
213 /**
214 * Stringify port number, resolve into service name where defined.
215 *
216 * \param port 2-byte port number, in host-byte-order.
217 * \param transport Transport protocol name (e.g. "udp", "tcp"), or NULL.
218 * \return Pointer to static result buffer.
219 *
220 * \sa getservent(3), services(5), nsswitch.conf(5).
221 */
222 const char *stringify_port(int port, const char *transport)
223 {
224 static char service[NI_MAXSERV];
225
226 if (port < 0 || port > 0xFFFF) {
227 snprintf(service, sizeof(service), "undefined (%d)", port);
228 } else {
229 struct servent *se = getservbyport(htons(port), transport);
230
231 if (se == NULL)
232 snprintf(service, sizeof(service), "%d", port);
233 else
234 snprintf(service, sizeof(service), "%s", se->s_name);
235 }
236 return service;
237 }
238
239 /**
240 * Determine the socket type for a given layer-4 protocol.
241 *
242 * \param l4type The symbolic name of the transport-layer protocol.
243 *
244 * \sa ip(7), socket(2).
245 */
246 static inline int sock_type(const unsigned l4type)
247 {
248 switch (l4type) {
249 case IPPROTO_UDP: return SOCK_DGRAM;
250 case IPPROTO_TCP: return SOCK_STREAM;
251 case IPPROTO_DCCP: return SOCK_DCCP;
252 }
253 return -1; /* not supported here */
254 }
255
256 /**
257 * Pretty-print transport-layer name.
258 */
259 static const char *layer4_name(const unsigned l4type)
260 {
261 switch (l4type) {
262 case IPPROTO_UDP: return "UDP";
263 case IPPROTO_TCP: return "TCP";
264 case IPPROTO_DCCP: return "DCCP";
265 }
266 return "UNKNOWN PROTOCOL";
267 }
268
269 /**
270 * Flowopts: Transport-layer independent encapsulation of socket options.
271 *
272 * These collect individual socket options into a queue, which is disposed of
273 * directly after makesock(). The 'pre_conn_opt' structure is for internal use
274 * only and should not be visible elsewhere.
275 *
276 * \sa setsockopt(2), \ref makesock().
277 */
278 struct pre_conn_opt {
279 int sock_level; /**< Second argument to setsockopt() */
280 int sock_option; /**< Third argument to setsockopt() */
281 char *opt_name; /**< Stringified \a sock_option */
282 void *opt_val; /**< Fourth argument to setsockopt() */
283 socklen_t opt_len; /**< Fifth argument to setsockopt() */
284
285 struct list_head node; /**< FIFO, as sockopt order matters. */
286 };
287
288 /** FIFO list of pre-connection socket options to be set */
289 struct flowopts {
290 struct list_head sockopts;
291 };
292
293 /**
294 * Allocate and initialize a flowopt queue.
295 *
296 * \return A new structure to be passed to \ref flowopt_add(). It is
297 * automatically deallocated in \ref makesock().
298 */
299 struct flowopts *flowopt_new(void)
300 {
301 struct flowopts *new = para_malloc(sizeof(*new));
302
303 INIT_LIST_HEAD(&new->sockopts);
304 return new;
305 }
306
307 /**
308 * Append new socket option to flowopt queue.
309 *
310 * \param fo The flowopt queue to append to.
311 * \param lev Level at which \a opt resides.
312 * \param opt New option to add.
313 * \param name Stringified name of \a opt.
314 * \param val The value to set \a opt to.
315 * \param len Length of \a val.
316 *
317 * \sa setsockopt(2).
318 */
319 void flowopt_add(struct flowopts *fo, int lev, int opt,
320 const char *name, const void *val, int len)
321 {
322 struct pre_conn_opt *new = para_malloc(sizeof(*new));
323
324 new->sock_option = opt;
325 new->sock_level = lev;
326 new->opt_name = para_strdup(name);
327
328 if (val == NULL) {
329 new->opt_val = NULL;
330 new->opt_len = 0;
331 } else {
332 new->opt_val = para_malloc(len);
333 new->opt_len = len;
334 memcpy(new->opt_val, val, len);
335 }
336
337 list_add_tail(&new->node, &fo->sockopts);
338 }
339
340 /** Set the entire bunch of pre-connection options at once. */
341 static void flowopt_setopts(int sockfd, struct flowopts *fo)
342 {
343 struct pre_conn_opt *pc;
344
345 if (fo == NULL)
346 return;
347
348 list_for_each_entry(pc, &fo->sockopts, node)
349 if (setsockopt(sockfd, pc->sock_level, pc->sock_option,
350 pc->opt_val, pc->opt_len) < 0) {
351 PARA_EMERG_LOG("Can not set %s socket option: %s",
352 pc->opt_name, strerror(errno));
353 exit(EXIT_FAILURE);
354 }
355 }
356
357 /**
358 * Deallocate all resources of a flowopts structure.
359 *
360 * \param fo A pointer as returned from flowopt_new().
361 *
362 * It's OK to pass \p NULL here in which case the function does nothing.
363 */
364 void flowopt_cleanup(struct flowopts *fo)
365 {
366 struct pre_conn_opt *cur, *next;
367
368 if (fo == NULL)
369 return;
370
371 list_for_each_entry_safe(cur, next, &fo->sockopts, node) {
372 free(cur->opt_name);
373 free(cur->opt_val);
374 free(cur);
375 }
376 free(fo);
377 }
378
379 /**
380 * Resolve an IPv4/IPv6 address.
381 *
382 * \param l4type The layer-4 type (\p IPPROTO_xxx).
383 * \param passive Whether \p AI_PASSIVE should be included as hint.
384 * \param host Remote or local hostname or IPv/6 address string.
385 * \param port_number Used to set the port in each returned address structure.
386 * \param result addrinfo structures are returned here.
387 *
388 * The interpretation of \a host depends on the value of \a passive. On a
389 * passive socket host is interpreted as an interface IPv4/6 address (can be
390 * left NULL). On an active socket, \a host is the peer DNS name or IPv4/6
391 * address to connect to.
392 *
393 * \return Standard.
394 *
395 * \sa getaddrinfo(3).
396 */
397 int lookup_address(unsigned l4type, bool passive, const char *host,
398 int port_number, struct addrinfo **result)
399 {
400 int ret;
401 char port[6]; /* port number has at most 5 digits */
402 struct addrinfo *addr = NULL, hints;
403
404 *result = NULL;
405 sprintf(port, "%d", port_number & 0xffff);
406 /* Set up address hint structure */
407 memset(&hints, 0, sizeof(hints));
408 hints.ai_family = AF_UNSPEC;
409 hints.ai_socktype = sock_type(l4type);
410 /*
411 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
412 * (and only then) pretend to be UDP.
413 */
414 if (l4type == IPPROTO_DCCP)
415 hints.ai_socktype = SOCK_DGRAM;
416 /* only use addresses available on the host */
417 hints.ai_flags = AI_ADDRCONFIG;
418 if (passive && host == NULL)
419 hints.ai_flags |= AI_PASSIVE;
420 /* Obtain local/remote address information */
421 ret = getaddrinfo(host, port, &hints, &addr);
422 if (ret != 0) {
423 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s\n",
424 layer4_name(l4type),
425 host? host : (passive? "[loopback]" : "[localhost]"),
426 port, gai_strerror(ret));
427 return -E_ADDRESS_LOOKUP;
428 }
429 *result = addr;
430 return 1;
431 }
432
433 /**
434 * Create an active or passive socket.
435 *
436 * \param l4type \p IPPROTO_TCP, \p IPPROTO_UDP, or \p IPPROTO_DCCP.
437 * \param passive Whether to call bind(2) or connect(2).
438 * \param ai Address information as obtained from \ref lookup_address().
439 * \param fo Socket options to be set before making the connection.
440 *
441 * bind(2) is called on passive sockets, and connect(2) on active sockets. The
442 * algorithm tries all possible address combinations until it succeeds. If \a
443 * fo is supplied, options are set but cleanup must be performed in the caller.
444 *
445 * \return File descriptor on success, \p E_MAKESOCK on errors.
446 *
447 * \sa \ref lookup_address(), \ref makesock(), ip(7), ipv6(7), bind(2),
448 * connect(2).
449 */
450 int makesock_addrinfo(unsigned l4type, bool passive, struct addrinfo *ai,
451 struct flowopts *fo)
452 {
453 int ret = -E_MAKESOCK, on = 1;
454
455 for (; ai; ai = ai->ai_next) {
456 int fd;
457 ret = socket(ai->ai_family, sock_type(l4type), l4type);
458 if (ret < 0) {
459 PARA_NOTICE_LOG("socket(): %s\n", strerror(errno));
460 continue;
461 }
462 fd = ret;
463 flowopt_setopts(fd, fo);
464 if (!passive) {
465 if (connect(fd, ai->ai_addr, ai->ai_addrlen) < 0) {
466 PARA_NOTICE_LOG("connect(): %s\n",
467 strerror(errno));
468 close(fd);
469 continue;
470 }
471 return fd;
472 }
473 /*
474 * Reuse the address on passive sockets to avoid failure on
475 * restart (protocols using listen()) and when creating
476 * multiple listener instances (UDP multicast).
477 */
478 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on,
479 sizeof(on)) == -1) {
480 PARA_NOTICE_LOG("setsockopt(): %s\n", strerror(errno));
481 close(fd);
482 continue;
483 }
484 if (bind(fd, ai->ai_addr, ai->ai_addrlen) < 0) {
485 PARA_NOTICE_LOG("bind(): %s\n", strerror(errno));
486 close(fd);
487 continue;
488 }
489 return fd;
490 }
491 return -E_MAKESOCK;
492 }
493
494 /**
495 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
496 *
497 * \param l4type The layer-4 type (\p IPPROTO_xxx).
498 * \param passive Whether this is a passive or active socket.
499 * \param host Passed to \ref lookup_address().
500 * \param port_number Passed to \ref lookup_address().
501 * \param fo Passed to \ref makesock_addrinfo().
502 *
503 * This creates a ready-made IPv4/v6 socket structure after looking up the
504 * necessary parameters. The function first calls \ref lookup_address() and
505 * passes the address information to makesock_addrinfo() to create and
506 * initialize the socket.
507 *
508 * \return The newly created file descriptor on success, a negative error code
509 * on failure.
510 *
511 * \sa \ref lookup_address(), \ref makesock_addrinfo().
512 */
513 int makesock(unsigned l4type, bool passive, const char *host, uint16_t port_number,
514 struct flowopts *fo)
515 {
516 struct addrinfo *ai;
517 int ret = lookup_address(l4type, passive, host, port_number, &ai);
518
519 if (ret >= 0)
520 ret = makesock_addrinfo(l4type, passive, ai, fo);
521 if (ai)
522 freeaddrinfo(ai);
523 if (ret < 0) {
524 PARA_ERROR_LOG("can not create %s socket %s#%d.\n",
525 layer4_name(l4type), host? host : (passive?
526 "[loopback]" : "[localhost]"), port_number);
527 }
528 return ret;
529 }
530
531 /**
532 * Create a passive / listening socket.
533 *
534 * \param l4type The transport-layer type (\p IPPROTO_xxx).
535 * \param addr Passed to \ref parse_url() if not NULL.
536 * \param port Ignored if addr contains a port number.
537 *
538 * \return Positive integer (socket descriptor) on success, negative value
539 * otherwise.
540 *
541 * \sa \ref makesock(), ip(7), ipv6(7), bind(2), listen(2).
542 */
543 int para_listen(unsigned l4type, const char *addr, uint16_t port)
544 {
545 char host[MAX_HOSTLEN];
546 int ret, fd, addr_port;
547
548 if (addr) {
549 if (!parse_url(addr, host, sizeof(host), &addr_port))
550 return -ERRNO_TO_PARA_ERROR(EINVAL);
551 if (addr_port > 0)
552 port = addr_port;
553 addr = host;
554 }
555 fd = makesock(l4type, true /* passive */, addr, port,
556 NULL /* no flowopts */);
557 if (fd > 0) {
558 ret = listen(fd, BACKLOG);
559 if (ret < 0) {
560 ret = errno;
561 close(fd);
562 return -ERRNO_TO_PARA_ERROR(ret);
563 }
564 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
565 layer4_name(l4type), port, fd);
566 }
567 return fd;
568 }
569
570 /**
571 * Create a socket which listens on all network addresses.
572 *
573 * \param l4type See \ref para_listen().
574 * \param port See \ref para_listen().
575 *
576 * This is a simple wrapper for \ref para_listen() which passes a NULL pointer
577 * as the address information.
578 *
579 * \return See \ref para_listen().
580 */
581 int para_listen_simple(unsigned l4type, uint16_t port)
582 {
583 return para_listen(l4type, NULL, port);
584 }
585
586 /**
587 * Determine IPv4/v6 socket address length.
588 * \param sa Container of IPv4 or IPv6 address.
589 * \return Address-family dependent address length.
590 */
591 static socklen_t salen(const struct sockaddr *sa)
592 {
593 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
594
595 return sa->sa_family == AF_INET6
596 ? sizeof(struct sockaddr_in6)
597 : sizeof(struct sockaddr_in);
598 }
599
600 /** True if @ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
601 static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
602 {
603 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
604
605 return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
606 }
607
608 /**
609 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
610 * \param ss Container of IPv4/6 address.
611 * \return Pointer to normalized address (may be static storage).
612 *
613 * \sa RFC 3493.
614 */
615 static const struct sockaddr *
616 normalize_ip_address(const struct sockaddr_storage *ss)
617 {
618 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
619
620 if (SS_IS_ADDR_V4MAPPED(ss)) {
621 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
622 static struct sockaddr_in ia;
623
624 ia.sin_family = AF_INET;
625 ia.sin_port = ia6->sin6_port;
626 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
627 return (const struct sockaddr *)&ia;
628 }
629 return (const struct sockaddr *)ss;
630 }
631
632 /**
633 * Generic/fallback MTU values
634 *
635 * These are taken from RFC 1122, RFC 2460, and RFC 5405.
636 * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
637 * to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
638 * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
639 * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
640 * UDP senders should use the respective minimum values of EMTU_S.
641 */
642 static inline int generic_mtu(const int af_type)
643 {
644 return af_type == AF_INET6 ? 1280 : 576;
645 }
646
647 /** Crude approximation of IP header overhead - neglecting options. */
648 static inline int estimated_header_overhead(const int af_type)
649 {
650 return af_type == AF_INET6 ? 40 : 20;
651 }
652
653 /**
654 * Get the maximum transport-layer message size (MMS_S).
655 *
656 * \param sockfd The socket file descriptor.
657 *
658 * The socket must be connected. See RFC 1122, 3.3.3. If the protocol family
659 * could not be determined, \p AF_INET is assumed.
660 *
661 * \return The maximum message size of the address family type.
662 */
663 int generic_max_transport_msg_size(int sockfd)
664 {
665 struct sockaddr_storage ss = {.ss_family = 0};
666 socklen_t sslen = sizeof(ss);
667 int af_type = AF_INET;
668
669 if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
670 PARA_ERROR_LOG("can not determine remote address type: %s\n",
671 strerror(errno));
672 } else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
673 af_type = ss.ss_family;
674 }
675 return generic_mtu(af_type) - estimated_header_overhead(af_type);
676 }
677
678 /**
679 * Look up the remote side of a connected socket structure.
680 *
681 * \param fd The socket descriptor of the connected socket.
682 *
683 * \return A static character string identifying hostname and port of the
684 * chosen side in numeric host:port format.
685 *
686 * \sa getsockname(2), getpeername(2), \ref parse_url(), getnameinfo(3),
687 * services(5), nsswitch.conf(5).
688 */
689 char *remote_name(int fd)
690 {
691 struct sockaddr_storage ss = {.ss_family = 0};
692 const struct sockaddr *sa;
693 socklen_t sslen = sizeof(ss);
694 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
695 static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
696 int ret;
697
698 if (getpeername(fd, (struct sockaddr *)&ss, &sslen) < 0) {
699 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
700 fd, strerror(errno));
701 snprintf(output, sizeof(output), "(unknown)");
702 return output;
703 }
704 sa = normalize_ip_address(&ss);
705 ret = getnameinfo(sa, salen(sa), hbuf, sizeof(hbuf), sbuf,
706 sizeof(sbuf), NI_NUMERICHOST | NI_NUMERICSERV);
707 if (ret) {
708 PARA_WARNING_LOG("hostname lookup error (%s).\n",
709 gai_strerror(ret));
710 snprintf(output, sizeof(output), "(lookup error)");
711 } else if (sa->sa_family == AF_INET6)
712 snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
713 else
714 snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
715 return output;
716 }
717
718 /**
719 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
720 *
721 * \param ss Container of IPv4/6 address.
722 * \param ia Extracted IPv4 address (different from 0) or 0 if unsuccessful.
723 *
724 * \sa RFC 3493.
725 */
726 void extract_v4_addr(const struct sockaddr_storage *ss, struct in_addr *ia)
727 {
728 const struct sockaddr *sa = normalize_ip_address(ss);
729
730 memset(ia, 0, sizeof(*ia));
731 if (sa->sa_family == AF_INET)
732 *ia = ((struct sockaddr_in *)sa)->sin_addr;
733 }
734
735 /**
736 * Compare the address part of IPv4/6 addresses.
737 *
738 * \param sa1 First address.
739 * \param sa2 Second address.
740 *
741 * \return True iff the IP address of \a sa1 and \a sa2 match.
742 */
743 bool sockaddr_equal(const struct sockaddr *sa1, const struct sockaddr *sa2)
744 {
745 if (!sa1 || !sa2)
746 return false;
747 if (sa1->sa_family != sa2->sa_family)
748 return false;
749 if (sa1->sa_family == AF_INET) {
750 struct sockaddr_in *a1 = (typeof(a1))sa1,
751 *a2 = (typeof (a2))sa2;
752 return a1->sin_addr.s_addr == a2->sin_addr.s_addr;
753 } else if (sa1->sa_family == AF_INET6) {
754 struct sockaddr_in6 *a1 = (typeof(a1))sa1,
755 *a2 = (typeof (a2))sa2;
756 return !memcmp(a1, a2, sizeof(*a1));
757 } else
758 return false;
759 }
760
761 /**
762 * Receive data from a file descriptor.
763 *
764 * \param fd The file descriptor.
765 * \param buf The buffer to write the data to.
766 * \param size The size of \a buf.
767 *
768 * Receive at most \a size bytes from file descriptor \a fd.
769 *
770 * \return The number of bytes received on success, negative on errors, zero if
771 * the peer has performed an orderly shutdown.
772 *
773 * \sa recv(2).
774 */
775 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
776 {
777 ssize_t n;
778
779 n = recv(fd, buf, size, 0);
780 if (n == -1)
781 return -ERRNO_TO_PARA_ERROR(errno);
782 return n;
783 }
784
785 /**
786 * Receive and write terminating NULL byte.
787 *
788 * \param fd The file descriptor.
789 * \param buf The buffer to write the data to.
790 * \param size The size of \a buf.
791 *
792 * Read at most \a size - 1 bytes from file descriptor \a fd and
793 * write a NULL byte at the end of the received data.
794 *
795 * \return The return value of the underlying call to \a recv_bin_buffer().
796 *
797 * \sa \ref recv_bin_buffer()
798 */
799 int recv_buffer(int fd, char *buf, size_t size)
800 {
801 int n;
802
803 assert(size);
804 n = recv_bin_buffer(fd, buf, size - 1);
805 if (n >= 0)
806 buf[n] = '\0';
807 else
808 *buf = '\0';
809 return n;
810 }
811
812 /**
813 * Wrapper around the accept system call.
814 *
815 * \param fd The listening socket.
816 * \param rfds An optional fd_set pointer.
817 * \param addr Structure which is filled in with the address of the peer socket.
818 * \param size Should contain the size of the structure pointed to by \a addr.
819 * \param new_fd Result pointer.
820 *
821 * Accept incoming connections on \a addr, retry if interrupted. If \a rfds is
822 * not \p NULL, return 0 if \a fd is not set in \a rfds without calling accept().
823 *
824 * \return Negative on errors, zero if no connections are present to be accepted,
825 * one otherwise.
826 *
827 * \sa accept(2).
828 */
829 int para_accept(int fd, fd_set *rfds, void *addr, socklen_t size, int *new_fd)
830 {
831 int ret;
832
833 if (rfds && !FD_ISSET(fd, rfds))
834 return 0;
835 do
836 ret = accept(fd, (struct sockaddr *) addr, &size);
837 while (ret < 0 && errno == EINTR);
838
839 if (ret >= 0) {
840 *new_fd = ret;
841 return 1;
842 }
843 if (errno == EAGAIN || errno == EWOULDBLOCK)
844 return 0;
845 return -ERRNO_TO_PARA_ERROR(errno);
846 }
847
848 /**
849 * Probe the list of DCCP CCIDs configured on this host.
850 * \param ccid_array Pointer to return statically allocated array in.
851 * \return Number of elements returned in \a ccid_array or error.
852 *
853 * NB: This feature is only available on Linux > 2.6.30; on older kernels
854 * ENOPROTOOPT ("Protocol not available") will be returned.
855 */
856 int dccp_available_ccids(uint8_t **ccid_array)
857 {
858 static uint8_t ccids[DCCP_MAX_HOST_CCIDS];
859 socklen_t nccids = sizeof(ccids);
860 int ret, fd;
861
862 ret = fd = makesock(IPPROTO_DCCP, 1, NULL, 0, NULL);
863 if (ret < 0)
864 return ret;
865
866 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
867 ccids, &nccids) < 0) {
868 ret = errno;
869 close(fd);
870 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
871 strerror(ret));
872 return -ERRNO_TO_PARA_ERROR(ret);
873 }
874
875 close(fd);
876 *ccid_array = ccids;
877 return nccids;
878 }
879
880 /*
881 * Prepare a structure for AF_UNIX socket addresses.
882 *
883 * This just copies name to the sun_path component of u, prepending a zero byte
884 * if abstract sockets are supported.
885 *
886 * The first call to this function tries to bind a socket to the abstract name
887 * space. The result of this test is stored in a static variable. Subsequent
888 * calls read this variable and create abstract sockets on systems that support
889 * them.
890 */
891 static int init_unix_addr(struct sockaddr_un *u, const char *name)
892 {
893 static int use_abstract;
894
895 if (strlen(name) + 1 >= UNIX_PATH_MAX)
896 return -E_NAME_TOO_LONG;
897 memset(u->sun_path, 0, UNIX_PATH_MAX);
898 u->sun_family = PF_UNIX;
899 if (use_abstract == 0) { /* executed only once */
900 int fd = socket(PF_UNIX, SOCK_STREAM, 0);
901 memcpy(u->sun_path, "\0x\0", 3);
902 if (bind(fd, (struct sockaddr *)u, sizeof(*u)) == 0)
903 use_abstract = 1; /* yes */
904 else
905 use_abstract = -1; /* no */
906 close(fd);
907 PARA_NOTICE_LOG("%susing abstract socket namespace\n",
908 use_abstract == 1? "" : "not ");
909 }
910 strcpy(u->sun_path + (use_abstract == 1? 1 : 0), name);
911 return 1;
912 }
913
914 /**
915 * Create a socket for local communication and listen on it.
916 *
917 * \param name The socket pathname.
918 *
919 * This function creates a passive local socket for sequenced, reliable,
920 * two-way, connection-based byte streams. The socket file descriptor is set to
921 * nonblocking mode and listen(2) is called to prepare the socket for
922 * accepting incoming connection requests.
923 *
924 * \return The file descriptor on success, negative error code on failure.
925 *
926 * \sa socket(2), \sa bind(2), \sa chmod(2), listen(2), unix(7).
927 */
928 int create_local_socket(const char *name)
929 {
930 struct sockaddr_un unix_addr;
931 int fd, ret;
932
933 ret = init_unix_addr(&unix_addr, name);
934 if (ret < 0)
935 return ret;
936 ret = socket(PF_UNIX, SOCK_STREAM, 0);
937 if (ret < 0)
938 return -ERRNO_TO_PARA_ERROR(errno);
939 fd = ret;
940 ret = mark_fd_nonblocking(fd);
941 if (ret < 0)
942 goto err;
943 ret = bind(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr));
944 if (ret < 0) {
945 ret = -ERRNO_TO_PARA_ERROR(errno);
946 goto err;
947 }
948 if (unix_addr.sun_path[0] != 0) { /* pathname socket */
949 mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP
950 | S_IROTH | S_IWOTH;
951 ret = -E_CHMOD;
952 if (chmod(name, mode) < 0)
953 goto err;
954 }
955 if (listen(fd , 5) < 0) {
956 ret = -ERRNO_TO_PARA_ERROR(errno);
957 goto err;
958 }
959 return fd;
960 err:
961 close(fd);
962 return ret;
963 }
964
965 /**
966 * Prepare, create, and connect to a Unix domain socket for local communication.
967 *
968 * \param name The socket pathname.
969 *
970 * This function creates a local socket for sequenced, reliable, two-way,
971 * connection-based byte streams.
972 *
973 * \return The file descriptor of the connected socket on success, negative on
974 * errors.
975 *
976 * \sa \ref create_local_socket(), unix(7), connect(2).
977 */
978 int connect_local_socket(const char *name)
979 {
980 struct sockaddr_un unix_addr;
981 int fd, ret;
982
983 PARA_DEBUG_LOG("connecting to %s\n", name);
984 fd = socket(PF_UNIX, SOCK_STREAM, 0);
985 if (fd < 0)
986 return -ERRNO_TO_PARA_ERROR(errno);
987 ret = init_unix_addr(&unix_addr, name);
988 if (ret < 0)
989 goto err;
990 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) != -1)
991 return fd;
992 ret = -ERRNO_TO_PARA_ERROR(errno);
993 err:
994 close(fd);
995 return ret;
996 }
997
998 #ifndef HAVE_UCRED
999 ssize_t send_cred_buffer(int sock, char *buf)
1000 {
1001 return write_buffer(sock, buf);
1002 }
1003 int recv_cred_buffer(int fd, char *buf, size_t size)
1004 {
1005 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
1006 }
1007 #else /* HAVE_UCRED */
1008
1009 /**
1010 * Send a buffer and the credentials of the current process to a socket.
1011 *
1012 * \param sock The file descriptor of the sending socket.
1013 * \param buf The zero-terminated buffer to send.
1014 *
1015 * \return On success, this call returns the number of bytes sent. On errors,
1016 * \p -E_SENDMSG is returned.
1017 *
1018 * \sa \ref recv_cred_buffer, sendmsg(2), socket(7), unix(7).
1019 */
1020 ssize_t send_cred_buffer(int sock, char *buf)
1021 {
1022 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
1023 struct msghdr msg;
1024 struct cmsghdr *cmsg;
1025 static struct iovec iov;
1026 struct ucred c;
1027 int ret;
1028
1029 /* Response data */
1030 iov.iov_base = buf;
1031 iov.iov_len = strlen(buf);
1032 c.pid = getpid();
1033 c.uid = getuid();
1034 c.gid = getgid();
1035 /* compose the message */
1036 memset(&msg, 0, sizeof(msg));
1037 msg.msg_iov = &iov;
1038 msg.msg_iovlen = 1;
1039 msg.msg_control = control;
1040 msg.msg_controllen = sizeof(control);
1041 /* attach the ucred struct */
1042 cmsg = CMSG_FIRSTHDR(&msg);
1043 cmsg->cmsg_level = SOL_SOCKET;
1044 cmsg->cmsg_type = SCM_CREDENTIALS;
1045 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
1046 *(struct ucred *)CMSG_DATA(cmsg) = c;
1047 msg.msg_controllen = cmsg->cmsg_len;
1048 ret = sendmsg(sock, &msg, 0);
1049 if (ret < 0)
1050 ret = -E_SENDMSG;
1051 return ret;
1052 }
1053
1054 static void dispose_fds(int *fds, unsigned num)
1055 {
1056 int i;
1057
1058 for (i = 0; i < num; i++)
1059 close(fds[i]);
1060 }
1061
1062 /**
1063 * Receive a buffer and the Unix credentials of the sending process.
1064 *
1065 * \param fd The file descriptor of the receiving socket.
1066 * \param buf The buffer to store the received message.
1067 * \param size The length of \a buf in bytes.
1068 *
1069 * \return Negative on errors, the user id of the sending process on success.
1070 *
1071 * \sa \ref send_cred_buffer and the references given there.
1072 */
1073 int recv_cred_buffer(int fd, char *buf, size_t size)
1074 {
1075 char control[255] __a_aligned(8);
1076 struct msghdr msg;
1077 struct cmsghdr *cmsg;
1078 struct iovec iov;
1079 int result = 0;
1080 int yes = 1;
1081 struct ucred cred;
1082
1083 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
1084 memset(&msg, 0, sizeof(msg));
1085 memset(buf, 0, size);
1086 iov.iov_base = buf;
1087 iov.iov_len = size;
1088 msg.msg_iov = &iov;
1089 msg.msg_iovlen = 1;
1090 msg.msg_control = control;
1091 msg.msg_controllen = sizeof(control);
1092 if (recvmsg(fd, &msg, 0) < 0)
1093 return -E_RECVMSG;
1094 result = -E_SCM_CREDENTIALS;
1095 cmsg = CMSG_FIRSTHDR(&msg);
1096 while (cmsg) {
1097 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
1098 == SCM_CREDENTIALS) {
1099 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
1100 result = cred.uid;
1101 } else
1102 if (cmsg->cmsg_level == SOL_SOCKET
1103 && cmsg->cmsg_type == SCM_RIGHTS) {
1104 dispose_fds((int *)CMSG_DATA(cmsg),
1105 (cmsg->cmsg_len - CMSG_LEN(0))
1106 / sizeof(int));
1107 }
1108 cmsg = CMSG_NXTHDR(&msg, cmsg);
1109 }
1110 return result;
1111 }
1112 #endif /* HAVE_UCRED */