aeeca20e41447d2f3912b3035e739219ff08c62d
[paraslash.git] / net.c
1 /*
2 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file net.c Networking-related helper functions. */
8
9 /*
10 * Since glibc 2.8, the _GNU_SOURCE feature test macro must be defined in order
11 * to obtain the definition of the ucred structure.
12 */
13 #define _GNU_SOURCE
14
15 #include <netdb.h>
16
17 /* At least NetBSD needs these. */
18 #ifndef AI_V4MAPPED
19 #define AI_V4MAPPED 0
20 #endif
21 #ifndef AI_ALL
22 #define AI_ALL 0
23 #endif
24 #ifndef AI_ADDRCONFIG
25 #define AI_ADDRCONFIG 0
26 #endif
27
28 #include <dirent.h>
29 #include <regex.h>
30 #include <openssl/rc4.h>
31
32 #include "para.h"
33 #include "error.h"
34 #include "crypt.h"
35 #include "net.h"
36 #include "string.h"
37 #include "list.h"
38 #include "fd.h"
39
40 /**
41 * Parse and validate IPv4 address/netmask string.
42 *
43 * \param cidr Address in CIDR notation
44 * \param addr Copy of the IPv4 address part of \a cidr
45 * \param addrlen Size of \a addr in bytes
46 * \param netmask Value of the netmask part in \a cidr or the
47 * default of 32 if not specified.
48 *
49 * \return Pointer to \a addr if succesful, NULL on error.
50 * \sa RFC 4632
51 */
52 char *parse_cidr(const char *cidr,
53 char *addr, ssize_t addrlen,
54 int32_t *netmask)
55 {
56 const char *o = cidr;
57 char *c = addr, *end = c + (addrlen - 1);
58
59 *netmask = 0x20;
60
61 if (cidr == NULL || addrlen < 1)
62 goto failed;
63
64 for (o = cidr; (*c = *o == '/'? '\0' : *o); c++, o++)
65 if (c == end)
66 goto failed;
67
68 if (*o == '/')
69 if (para_atoi32(++o, netmask) < 0 ||
70 *netmask < 0 || *netmask > 0x20)
71 goto failed;
72
73 if (is_valid_ipv4_address(addr))
74 return addr;
75 failed:
76 *addr = '\0';
77 return NULL;
78 }
79
80
81 /**
82 * Match string as a candidate IPv4 address.
83 *
84 * \param address The string to match.
85 * \return True if \a address has "dot-quad" format.
86 */
87 static bool is_v4_dot_quad(const char *address)
88 {
89 bool result;
90 regex_t r;
91
92 assert(para_regcomp(&r, "^([0-9]+\\.){3}[0-9]+$",
93 REG_EXTENDED | REG_NOSUB) >= 0);
94 result = regexec(&r, address, 0, NULL, 0) == 0;
95 regfree(&r);
96 return result;
97 }
98
99 /**
100 * Perform basic syntax checking on the host-part of an URL:
101 *
102 * - Since ':' is invalid in IPv4 addresses and DNS names, the
103 * presence of ':' causes interpretation as IPv6 address;
104 * - next the first-match-wins algorithm from RFC 3986 is applied;
105 * - else the string is considered as DNS name, to be resolved later.
106 *
107 * \param host The host string to check.
108 * \return True if \a host passes the syntax checks.
109 *
110 * \sa RFC 3986, 3.2.2; RFC 1123, 2.1; RFC 1034, 3.5
111 */
112 static bool host_string_ok(const char *host)
113 {
114 if (host == NULL || *host == '\0')
115 return false;
116 if (strchr(host, ':') != NULL)
117 return is_valid_ipv6_address(host);
118 if (is_v4_dot_quad(host))
119 return is_valid_ipv4_address(host);
120 return true;
121 }
122
123 /**
124 * Parse and validate URL string.
125 *
126 * The URL syntax is loosely based on RFC 3986, supporting one of
127 * - "["host"]"[:port] for native IPv6 addresses and
128 * - host[:port] for IPv4 hostnames and DNS names.
129 *
130 * Native IPv6 addresses must be enclosed in square brackets, since
131 * otherwise there is an ambiguity with the port separator `:'.
132 * The 'port' part is always considered to be a number; if absent,
133 * it is set to -1, to indicate that a default port is to be used.
134 *
135 * The following are valid examples:
136 * - 10.10.1.1
137 * - 10.10.1.2:8000
138 * - localhost
139 * - localhost:8001
140 * - [::1]:8000
141 * - [badc0de::1]
142 *
143 * \param url The URL string to take apart.
144 * \param host To return the copied host part of \a url.
145 * \param hostlen The maximum length of \a host.
146 * \param port To return the port number (if any) of \a url.
147 *
148 * \return Pointer to \a host, or NULL if failed.
149 * If NULL is returned, \a host and \a portnum are undefined. If no
150 * port number was present in \a url, \a portnum is set to -1.
151 *
152 * \sa RFC 3986, 3.2.2/3.2.3
153 */
154 char *parse_url(const char *url,
155 char *host, ssize_t hostlen,
156 int32_t *port)
157 {
158 const char *o = url;
159 char *c = host, *end = c + (hostlen - 1);
160
161 *port = -1;
162
163 if (o == NULL || hostlen < 1)
164 goto failed;
165
166 if (*o == '[') {
167 for (++o; (*c = *o == ']' ? '\0' : *o); c++, o++)
168 if (c == end)
169 goto failed;
170
171 if (*o++ != ']' || (*o != '\0' && *o != ':'))
172 goto failed;
173 } else {
174 for (; (*c = *o == ':'? '\0' : *o); c++, o++)
175 if (c == end)
176 goto failed;
177 }
178
179 if (*o == ':')
180 if (para_atoi32(++o, port) < 0 ||
181 *port < 0 || *port > 0xffff)
182 goto failed;
183
184 if (host_string_ok(host))
185 return host;
186 failed:
187 *host = '\0';
188 return NULL;
189 }
190
191 /**
192 * Stringify port number, resolve into service name where defined.
193 * \param port 2-byte port number, in host-byte-order.
194 * \param transport Transport protocol name (e.g. "udp", "tcp"), or NULL.
195 * \return Pointer to static result buffer.
196 *
197 * \sa getservent(3), services(5), nsswitch.conf(5)
198 */
199 const char *stringify_port(int port, const char *transport)
200 {
201 static char service[NI_MAXSERV];
202
203 if (port < 0 || port > 0xFFFF) {
204 snprintf(service, sizeof(service), "undefined (%d)", port);
205 } else {
206 struct servent *se = getservbyport(htons(port), transport);
207
208 if (se == NULL)
209 snprintf(service, sizeof(service), "%u", port);
210 else
211 snprintf(service, sizeof(service), "%s", se->s_name);
212 }
213 return service;
214 }
215
216 /**
217 * Determine the socket type for a given layer-4 protocol.
218 *
219 * \param l4type The symbolic name of the transport-layer protocol.
220 *
221 * \sa ip(7), socket(2)
222 */
223 static inline int sock_type(const unsigned l4type)
224 {
225 switch (l4type) {
226 case IPPROTO_UDP: return SOCK_DGRAM;
227 case IPPROTO_TCP: return SOCK_STREAM;
228 case IPPROTO_DCCP: return SOCK_DCCP;
229 }
230 return -1; /* not supported here */
231 }
232
233 /**
234 * Pretty-print transport-layer name.
235 */
236 static const char *layer4_name(const unsigned l4type)
237 {
238 switch (l4type) {
239 case IPPROTO_UDP: return "UDP";
240 case IPPROTO_TCP: return "TCP";
241 case IPPROTO_DCCP: return "DCCP";
242 }
243 return "UNKNOWN PROTOCOL";
244 }
245
246 /**
247 * Flowopts: Transport-layer independent encapsulation of socket options.
248 *
249 * These collect individual socket options into a queue, which is disposed of
250 * directly after makesock(). The 'pre_conn_opt' structure is for internal use
251 * only and should not be visible elsewhere.
252 *
253 * \sa setsockopt(2), makesock()
254 */
255 struct pre_conn_opt {
256 int sock_level; /**< Second argument to setsockopt() */
257 int sock_option; /**< Third argument to setsockopt() */
258 char *opt_name; /**< Stringified \a sock_option */
259 void *opt_val; /**< Fourth argument to setsockopt() */
260 socklen_t opt_len; /**< Fifth argument to setsockopt() */
261
262 struct list_head node; /**< FIFO, as sockopt order matters. */
263 };
264
265 /** FIFO list of pre-connection socket options to be set */
266 struct flowopts {
267 struct list_head sockopts;
268 };
269
270 struct flowopts *flowopt_new(void)
271 {
272 struct flowopts *new = para_malloc(sizeof(*new));
273
274 INIT_LIST_HEAD(&new->sockopts);
275 return new;
276 }
277
278 /**
279 * Append new socket option to flowopt queue.
280 *
281 * \param fo The flowopt queue to append to.
282 * \param lev Level at which \opt resides.
283 * \param opt New option to add.
284 * \param name Stringified name of \a opt.
285 * \param val The value to set \a opt to.
286 * \param len Length of \a val.
287 *
288 * \sa setsockopt(2)
289 */
290 void flowopt_add(struct flowopts *fo, int lev, int opt,
291 char *name, const void *val, int len)
292 {
293 struct pre_conn_opt *new = para_malloc(sizeof(*new));
294
295 new->sock_option = opt;
296 new->sock_level = lev;
297 new->opt_name = para_strdup(name);
298
299 if (val == NULL) {
300 new->opt_val = NULL;
301 new->opt_len = 0;
302 } else {
303 new->opt_val = para_malloc(len);
304 new->opt_len = len;
305 memcpy(new->opt_val, val, len);
306 }
307
308 list_add_tail(&new->node, &fo->sockopts);
309 }
310
311 void flowopt_add_bool(struct flowopts *fo, int lev, int opt,
312 char *optname, bool on_or_off)
313 {
314 int on = on_or_off; /* kernel takes 'int' */
315
316 flowopt_add(fo, lev, opt, optname, &on, sizeof(on));
317 }
318
319 /** Set the entire bunch of pre-connection options at once. */
320 static void flowopt_setopts(int sockfd, struct flowopts *fo)
321 {
322 struct pre_conn_opt *pc;
323
324 if (fo == NULL)
325 return;
326
327 list_for_each_entry(pc, &fo->sockopts, node)
328 if (setsockopt(sockfd, pc->sock_level, pc->sock_option,
329 pc->opt_val, pc->opt_len) < 0) {
330 PARA_EMERG_LOG("Can not set %s socket option: %s",
331 pc->opt_name, strerror(errno));
332 exit(EXIT_FAILURE);
333 }
334 }
335
336 static void flowopt_cleanup(struct flowopts *fo)
337 {
338 struct pre_conn_opt *cur, *next;
339
340 if (fo == NULL)
341 return;
342
343 list_for_each_entry_safe(cur, next, &fo->sockopts, node) {
344 free(cur->opt_name);
345 free(cur->opt_val);
346 free(cur);
347 }
348 free(fo);
349 }
350
351 /**
352 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
353 *
354 * \param l3type The layer-3 type (\p AF_INET, \p AF_INET6, \p AF_UNSPEC).
355 * \param l4type The layer-4 type (\p IPPROTO_xxx).
356 * \param passive Whether this is a passive (1) or active (0) socket.
357 * \param host Remote or local hostname or IPv/6 address string.
358 * \param port_number Decimal port number.
359 * \param fo Socket options to be set before making the connection.
360 *
361 * This creates a ready-made IPv4/v6 socket structure after looking up the
362 * necessary parameters. The interpretation of \a host depends on the value of
363 * \a passive:
364 * - on a passive socket host is interpreted as an interface IPv4/6 address
365 * (can be left NULL);
366 * - on an active socket, \a host is the peer DNS name or IPv4/6 address
367 * to connect to;
368 * - \a port_number is in either case the numeric port number (not service
369 * string).
370 *
371 * Furthermore, bind(2) is called on passive sockets, and connect(2) on active
372 * sockets. The algorithm tries all possible address combinations until it
373 * succeeds. If \a fo is supplied, options are set and cleanup is performed.
374 *
375 * \return This function returns 1 on success and \a -E_ADDRESS_LOOKUP when no
376 * matching connection could be set up (with details in the error log).
377 *
378 * \sa ipv6(7), getaddrinfo(3), bind(2), connect(2).
379 */
380 int makesock(unsigned l4type, bool passive,
381 const char *host, uint16_t port_number,
382 struct flowopts *fo)
383 {
384 struct addrinfo *local = NULL, *src,
385 *remote = NULL, *dst, hints;
386 unsigned int l3type = AF_UNSPEC;
387 int rc, sockfd = -1,
388 socktype = sock_type(l4type);
389 char port[6]; /* port number has at most 5 digits */
390
391 sprintf(port, "%u", port_number);
392 /* Set up address hint structure */
393 memset(&hints, 0, sizeof(hints));
394 hints.ai_family = l3type;
395 hints.ai_socktype = socktype;
396 /*
397 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
398 * (and only then) pretend to be UDP.
399 */
400 if (l4type == IPPROTO_DCCP)
401 hints.ai_socktype = SOCK_DGRAM;
402
403 /* only use addresses available on the host */
404 hints.ai_flags = AI_ADDRCONFIG;
405 if (l3type == AF_INET6)
406 /* use v4-mapped-v6 if no v6 addresses found */
407 hints.ai_flags |= AI_V4MAPPED | AI_ALL;
408
409 if (passive && host == NULL)
410 hints.ai_flags |= AI_PASSIVE;
411
412 /* Obtain local/remote address information */
413 if ((rc = getaddrinfo(host, port, &hints, passive ? &local : &remote))) {
414 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s.\n",
415 layer4_name(l4type),
416 host? host : (passive? "[loopback]" : "[localhost]"),
417 port, gai_strerror(rc));
418 return -E_ADDRESS_LOOKUP;
419 }
420
421 /* Iterate over all src/dst combination, exhausting dst first */
422 for (src = local, dst = remote; src != NULL || dst != NULL; /* no op */ ) {
423 if (src && dst && src->ai_family == AF_INET
424 && dst->ai_family == AF_INET6)
425 goto get_next_dst; /* v4 -> v6 is not possible */
426
427 sockfd = socket(src ? src->ai_family : dst->ai_family,
428 socktype, l4type);
429 if (sockfd < 0)
430 goto get_next_dst;
431
432 flowopt_setopts(sockfd, fo);
433
434 if (src) {
435 if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
436 close(sockfd);
437 goto get_next_src;
438 }
439 if (!dst) /* bind-only completed successfully */
440 break;
441 }
442
443 if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
444 break; /* connection completed successfully */
445 close(sockfd);
446 get_next_dst:
447 if (dst && (dst = dst->ai_next))
448 continue;
449 get_next_src:
450 if (src && (src = src->ai_next)) /* restart inner loop */
451 dst = remote;
452 }
453 if (local)
454 freeaddrinfo(local);
455 if (remote)
456 freeaddrinfo(remote);
457 flowopt_cleanup(fo);
458
459 if (src == NULL && dst == NULL) {
460 rc = errno;
461 PARA_ERROR_LOG("can not create %s socket %s#%s.\n",
462 layer4_name(l4type), host? host : (passive?
463 "[loopback]" : "[localhost]"), port);
464 return -ERRNO_TO_PARA_ERROR(rc);
465 }
466 return sockfd;
467 }
468
469 /**
470 * Create a passive / listening socket.
471 *
472 * \param l4type The transport-layer type (\p IPPROTO_xxx).
473 * \param port The decimal port number to listen on.
474 * \param fo Flowopts (if any) to set before starting to listen.
475 *
476 * \return Positive integer (socket descriptor) on success, negative value
477 * otherwise.
478 *
479 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
480 */
481 int para_listen(unsigned l4type, uint16_t port, struct flowopts *fo)
482 {
483 int fd, ret;
484
485 if (fo == NULL)
486 fo = flowopt_new();
487
488 /* Reuse the address to avoid failure on restart. */
489 OPT_ENABLE(fo, SOL_SOCKET, SO_REUSEADDR);
490
491 fd = makesock(l4type, 1, NULL, port, fo);
492 if (fd > 0) {
493 ret = listen(fd, BACKLOG);
494 if (ret < 0) {
495 ret = errno;
496 close(fd);
497 return -ERRNO_TO_PARA_ERROR(ret);
498 }
499 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
500 layer4_name(l4type), port, fd);
501 }
502 return fd;
503 }
504
505 /**
506 * Determine IPv4/v6 socket address length.
507 * \param sa Container of IPv4 or IPv6 address.
508 * \return Address-family dependent address length.
509 */
510 static socklen_t salen(const struct sockaddr *sa)
511 {
512 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
513
514 return sa->sa_family == AF_INET6
515 ? sizeof(struct sockaddr_in6)
516 : sizeof(struct sockaddr_in);
517 }
518
519 /**
520 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
521 * \param ss Container of IPv4/6 address.
522 * \return Pointer to normalized address (may be static storage).
523 *
524 * \sa RFC 3493
525 */
526 static const struct sockaddr *
527 normalize_ip_address(const struct sockaddr_storage *ss)
528 {
529 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
530
531 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
532
533 if (ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr)) {
534 static struct sockaddr_in ia;
535
536 ia.sin_family = AF_INET;
537 ia.sin_port = ia6->sin6_port;
538 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
539 return (const struct sockaddr *)&ia;
540 }
541 return (const struct sockaddr *)ss;
542 }
543
544 /**
545 * Print numeric host and port number (beware - uses static char).
546 *
547 * \param sa The IPv4/IPv6 socket address to use.
548 *
549 * \sa getnameinfo(3), services(5), nsswitch.conf(5)
550 */
551 static char *host_and_port(const struct sockaddr_storage *ss)
552 {
553 const struct sockaddr *sa = normalize_ip_address(ss);
554 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
555 static char output[sizeof(hbuf) + sizeof(sbuf) + 2];
556 int ret;
557
558 ret = getnameinfo(sa, salen(sa),
559 hbuf, sizeof(hbuf),
560 sbuf, sizeof(sbuf),
561 NI_NUMERICHOST);
562 if (ret == 0) {
563 snprintf(output, sizeof(output), "%s#%s", hbuf, sbuf);
564 } else {
565 snprintf(output, sizeof(output), "(unknown)");
566 PARA_WARNING_LOG("hostname lookup error (%s).\n",
567 gai_strerror(ret));
568 }
569 return output;
570 }
571
572 /**
573 * Look up the local or remote side of a connected socket structure.
574 *
575 * \param fd The socket descriptor of the connected socket.
576 * \param getname Either \p getsockname() for local, or \p getpeername() for
577 * remote side.
578 *
579 * \return A static character string identifying hostname and port of the
580 * chosen side.
581 *
582 * \sa getsockname(2), getpeername(2).
583 */
584 static char *__get_sock_name(int fd, int (*getname)(int, struct sockaddr*,
585 socklen_t *))
586 {
587 struct sockaddr_storage ss;
588 socklen_t sslen = sizeof(ss);
589
590 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
591 static char *dont_know = "(don't know)";
592 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
593 fd, strerror(errno));
594 return dont_know;
595 }
596 return host_and_port(&ss);
597 }
598
599 /**
600 * Look up the local side of a connected socket structure.
601 *
602 * \param sockfd The file descriptor of the socket.
603 *
604 * \return A pointer to a static buffer containing hostname an port. This
605 * buffer must not be freed by the caller.
606 *
607 * \sa remote_name().
608 */
609 char *local_name(int sockfd)
610 {
611 return __get_sock_name(sockfd, getsockname);
612 }
613
614 /**
615 * Look up the remote side of a connected socket structure.
616 *
617 * \param sockfd The file descriptor of the socket.
618 *
619 * \return Analogous to the return value of \ref local_name() but for the
620 * remote side.
621 *
622 * \sa local_name().
623 */
624 char *remote_name(int sockfd)
625 {
626 return __get_sock_name(sockfd, getpeername);
627 }
628
629 /**
630 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
631 * \param ss Container of IPv4/6 address
632 * \return Extracted IPv4 address (different from 0) or 0 if unsuccessful.
633 *
634 * \sa RFC 3493
635 */
636 struct in_addr extract_v4_addr(const struct sockaddr_storage *ss)
637 {
638 struct in_addr ia = {.s_addr = 0};
639 const struct sockaddr *sa = normalize_ip_address(ss);
640
641 if (sa->sa_family == AF_INET)
642 ia = ((struct sockaddr_in *)sa)->sin_addr;
643 return ia;
644 }
645
646 /**
647 * Send a binary buffer.
648 *
649 * \param fd The file descriptor.
650 * \param buf The buffer to be sent.
651 * \param len The length of \a buf.
652 *
653 * Send out the buffer and try to resend the remaining part in case of short
654 * writes.
655 *
656 * \return Standard.
657 */
658 int send_bin_buffer(int fd, const char *buf, size_t len)
659 {
660 if (!len)
661 PARA_CRIT_LOG("len == 0\n");
662 return write_all(fd, buf, &len);
663 }
664
665 /**
666 * Send a \p NULL-terminated buffer.
667 *
668 * \param fd The file descriptor.
669 * \param buf The null-terminated buffer to be send.
670 *
671 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
672 *
673 * \return Standard.
674 */
675 int send_buffer(int fd, const char *buf)
676 {
677 return send_bin_buffer(fd, buf, strlen(buf));
678 }
679
680 /**
681 * Send a buffer given by a format string.
682 *
683 * \param fd The file descriptor.
684 * \param fmt A format string.
685 *
686 * \return Standard.
687 */
688 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
689 {
690 char *msg;
691 int ret;
692
693 PARA_VSPRINTF(fmt, msg);
694 ret = send_buffer(fd, msg);
695 free(msg);
696 return ret;
697 }
698
699 /**
700 * Receive data from a file descriptor.
701 *
702 * \param fd The file descriptor.
703 * \param buf The buffer to write the data to.
704 * \param size The size of \a buf.
705 *
706 * Receive at most \a size bytes from file descriptor \a fd.
707 *
708 * \return The number of bytes received on success, negative on errors, zero if
709 * the peer has performed an orderly shutdown.
710 *
711 * \sa recv(2).
712 */
713 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
714 {
715 ssize_t n;
716
717 n = recv(fd, buf, size, 0);
718 if (n == -1)
719 return -ERRNO_TO_PARA_ERROR(errno);
720 return n;
721 }
722
723 /**
724 * Receive and write terminating NULL byte.
725 *
726 * \param fd The file descriptor.
727 * \param buf The buffer to write the data to.
728 * \param size The size of \a buf.
729 *
730 * Read at most \a size - 1 bytes from file descriptor \a fd and
731 * write a NULL byte at the end of the received data.
732 *
733 * \return The return value of the underlying call to \a recv_bin_buffer().
734 *
735 * \sa recv_bin_buffer()
736 */
737 int recv_buffer(int fd, char *buf, size_t size)
738 {
739 int n;
740
741 assert(size);
742 n = recv_bin_buffer(fd, buf, size - 1);
743 if (n >= 0)
744 buf[n] = '\0';
745 else
746 *buf = '\0';
747 return n;
748 }
749
750 /**
751 * Wrapper around the accept system call.
752 *
753 * \param fd The listening socket.
754 * \param addr Structure which is filled in with the address of the peer socket.
755 * \param size Should contain the size of the structure pointed to by \a addr.
756 *
757 * Accept incoming connections on \a addr. Retry if interrupted.
758 *
759 * \return The new file descriptor on success, negative on errors.
760 *
761 * \sa accept(2).
762 */
763 int para_accept(int fd, void *addr, socklen_t size)
764 {
765 int new_fd;
766
767 do
768 new_fd = accept(fd, (struct sockaddr *) addr, &size);
769 while (new_fd < 0 && errno == EINTR);
770 return new_fd < 0? -ERRNO_TO_PARA_ERROR(errno) : new_fd;
771 }
772
773 /**
774 * Probe the list of DCCP CCIDs supported locally by the host.
775 * \param ccids Array to be filled in.
776 * \param nccids Length of \a ccids.
777 * \return Pointer to \a ccids, NULL on failure.
778 *
779 * NB: This feature is only available on Linux > 2.6.30; on older kernels
780 * ENOPROTOOPT ("Protocol not available") will be returned.
781 */
782 const uint8_t *dccp_available_ccids(uint8_t *ccids, uint8_t *nccids)
783 {
784 int fd = makesock(IPPROTO_DCCP, 1, NULL, 0, NULL);
785
786 if (fd < 0)
787 return NULL;
788
789 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
790 ccids, (socklen_t *)nccids) < 0) {
791 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
792 strerror(errno));
793 *nccids = 0;
794 }
795 close(fd);
796
797 return *nccids ? ccids : NULL;
798 }
799
800 /**
801 * Prepare a structure for \p AF_UNIX socket addresses.
802 *
803 * \param u Pointer to the struct to be prepared.
804 * \param name The socket pathname.
805 *
806 * This just copies \a name to the sun_path component of \a u.
807 *
808 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
809 * than \p UNIX_PATH_MAX.
810 */
811 static int init_unix_addr(struct sockaddr_un *u, const char *name)
812 {
813 if (strlen(name) >= UNIX_PATH_MAX)
814 return -E_NAME_TOO_LONG;
815 memset(u->sun_path, 0, UNIX_PATH_MAX);
816 u->sun_family = PF_UNIX;
817 strcpy(u->sun_path, name);
818 return 1;
819 }
820
821 /**
822 * Prepare, create, and bind a socket for local communication.
823 *
824 * \param name The socket pathname.
825 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
826 * \param mode The desired mode of the socket.
827 *
828 * This function creates a local socket for sequenced, reliable,
829 * two-way, connection-based byte streams.
830 *
831 * \return The file descriptor, on success, negative on errors.
832 *
833 * \sa socket(2)
834 * \sa bind(2)
835 * \sa chmod(2)
836 */
837 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
838 mode_t mode)
839 {
840 int fd, ret;
841
842 ret = init_unix_addr(unix_addr, name);
843 if (ret < 0)
844 return ret;
845 ret = socket(PF_UNIX, SOCK_STREAM, 0);
846 if (ret < 0)
847 return -ERRNO_TO_PARA_ERROR(errno);
848 fd = ret;
849 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
850 if (ret < 0) {
851 ret = -ERRNO_TO_PARA_ERROR(errno);
852 goto err;
853 }
854 ret = -E_CHMOD;
855 if (chmod(name, mode) < 0)
856 goto err;
857 return fd;
858 err:
859 close(fd);
860 return ret;
861 }
862
863 /**
864 * Prepare, create, and connect to a Unix domain socket for local communication.
865 *
866 * \param name The socket pathname.
867 *
868 * This function creates a local socket for sequenced, reliable, two-way,
869 * connection-based byte streams.
870 *
871 * \return The file descriptor, on success, negative on errors.
872 *
873 * \sa create_local_socket(), unix(7), connect(2).
874 */
875 int create_remote_socket(const char *name)
876 {
877 struct sockaddr_un unix_addr;
878 int fd, ret;
879
880 ret = init_unix_addr(&unix_addr, name);
881 if (ret < 0)
882 return ret;
883 fd = socket(PF_UNIX, SOCK_STREAM, 0);
884 if (fd < 0)
885 return -ERRNO_TO_PARA_ERROR(errno);
886 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) == -1) {
887 ret = -ERRNO_TO_PARA_ERROR(errno);
888 goto err;
889 }
890 return fd;
891 err:
892 close(fd);
893 return ret;
894 }
895
896 #ifndef HAVE_UCRED
897 ssize_t send_cred_buffer(int sock, char *buf)
898 {
899 return send_buffer(sock, buf);
900 }
901 int recv_cred_buffer(int fd, char *buf, size_t size)
902 {
903 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
904 }
905 #else /* HAVE_UCRED */
906 /**
907 * Send \p NULL-terminated buffer and Unix credentials of the current process.
908 *
909 * \param sock The socket file descriptor.
910 * \param buf The buffer to be sent.
911 *
912 * \return On success, this call returns the number of characters sent. On
913 * error, \p -E_SENDMSG is returned.
914 *
915 * \sa sendmsg(2), okir's Black Hats Manual.
916 */
917 ssize_t send_cred_buffer(int sock, char *buf)
918 {
919 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
920 struct msghdr msg;
921 struct cmsghdr *cmsg;
922 static struct iovec iov;
923 struct ucred c;
924 int ret;
925
926 /* Response data */
927 iov.iov_base = buf;
928 iov.iov_len = strlen(buf);
929 c.pid = getpid();
930 c.uid = getuid();
931 c.gid = getgid();
932 /* compose the message */
933 memset(&msg, 0, sizeof(msg));
934 msg.msg_iov = &iov;
935 msg.msg_iovlen = 1;
936 msg.msg_control = control;
937 msg.msg_controllen = sizeof(control);
938 /* attach the ucred struct */
939 cmsg = CMSG_FIRSTHDR(&msg);
940 cmsg->cmsg_level = SOL_SOCKET;
941 cmsg->cmsg_type = SCM_CREDENTIALS;
942 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
943 *(struct ucred *)CMSG_DATA(cmsg) = c;
944 msg.msg_controllen = cmsg->cmsg_len;
945 ret = sendmsg(sock, &msg, 0);
946 if (ret < 0)
947 ret = -E_SENDMSG;
948 return ret;
949 }
950
951 static void dispose_fds(int *fds, unsigned num)
952 {
953 int i;
954
955 for (i = 0; i < num; i++)
956 close(fds[i]);
957 }
958
959 /**
960 * Receive a buffer and the Unix credentials of the sending process.
961 *
962 * \param fd the socket file descriptor.
963 * \param buf the buffer to store the message.
964 * \param size the size of \a buffer.
965 *
966 * \return negative on errors, the user id on success.
967 *
968 * \sa recvmsg(2), okir's Black Hats Manual.
969 */
970 int recv_cred_buffer(int fd, char *buf, size_t size)
971 {
972 char control[255];
973 struct msghdr msg;
974 struct cmsghdr *cmsg;
975 struct iovec iov;
976 int result = 0;
977 int yes = 1;
978 struct ucred cred;
979
980 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
981 memset(&msg, 0, sizeof(msg));
982 memset(buf, 0, size);
983 iov.iov_base = buf;
984 iov.iov_len = size;
985 msg.msg_iov = &iov;
986 msg.msg_iovlen = 1;
987 msg.msg_control = control;
988 msg.msg_controllen = sizeof(control);
989 if (recvmsg(fd, &msg, 0) < 0)
990 return -E_RECVMSG;
991 result = -E_SCM_CREDENTIALS;
992 cmsg = CMSG_FIRSTHDR(&msg);
993 while (cmsg) {
994 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
995 == SCM_CREDENTIALS) {
996 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
997 result = cred.uid;
998 } else
999 if (cmsg->cmsg_level == SOL_SOCKET
1000 && cmsg->cmsg_type == SCM_RIGHTS) {
1001 dispose_fds((int *) CMSG_DATA(cmsg),
1002 (cmsg->cmsg_len - CMSG_LEN(0))
1003 / sizeof(int));
1004 }
1005 cmsg = CMSG_NXTHDR(&msg, cmsg);
1006 }
1007 return result;
1008 }
1009 #endif /* HAVE_UCRED */
1010
1011 /**
1012 * Receive a buffer and check for a pattern.
1013 *
1014 * \param fd The file descriptor to receive from.
1015 * \param pattern The expected pattern.
1016 * \param bufsize The size of the internal buffer.
1017 *
1018 * \return Positive if \a pattern was received, negative otherwise.
1019 *
1020 * This function tries to receive at most \a bufsize bytes from file descriptor
1021 * \a fd. If at least \p strlen(\a pattern) bytes were received, the beginning
1022 * of the received buffer is compared with \a pattern, ignoring case.
1023 *
1024 * \sa recv_buffer(), \sa strncasecmp(3).
1025 */
1026 int recv_pattern(int fd, const char *pattern, size_t bufsize)
1027 {
1028 size_t len = strlen(pattern);
1029 char *buf = para_malloc(bufsize + 1);
1030 int ret = -E_RECV_PATTERN, n = recv_buffer(fd, buf, bufsize + 1);
1031
1032 if (n < len)
1033 goto out;
1034 if (strncasecmp(buf, pattern, len))
1035 goto out;
1036 ret = 1;
1037 out:
1038 if (ret < 0) {
1039 PARA_NOTICE_LOG("did not receive pattern '%s'\n", pattern);
1040 if (n > 0)
1041 PARA_NOTICE_LOG("recvd %d bytes: %s\n", n, buf);
1042 else if (n < 0)
1043 PARA_NOTICE_LOG("%s\n", para_strerror(-n));
1044 }
1045 free(buf);
1046 return ret;
1047 }