d85321d931d51f2d21a0fa8e8ea160df432b1ece
[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 l3type, unsigned l4type, int passive,
381 const char *host, unsigned short port_number,
382 struct flowopts *fo)
383 {
384 struct addrinfo *local = NULL, *src,
385 *remote = NULL, *dst, hints;
386 int rc, on = 1, sockfd = -1,
387 socktype = sock_type(l4type);
388 char port[6]; /* port number has at most 5 digits */
389
390 sprintf(port, "%u", port_number);
391 /* Set up address hint structure */
392 memset(&hints, 0, sizeof(hints));
393 hints.ai_family = l3type;
394 hints.ai_socktype = socktype;
395 /*
396 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
397 * (and only then) pretend to be UDP.
398 */
399 if (l4type == IPPROTO_DCCP)
400 hints.ai_socktype = SOCK_DGRAM;
401
402 /* only use addresses available on the host */
403 hints.ai_flags = AI_ADDRCONFIG;
404 if (l3type == AF_INET6)
405 /* use v4-mapped-v6 if no v6 addresses found */
406 hints.ai_flags |= AI_V4MAPPED | AI_ALL;
407
408 if (passive && host == NULL)
409 hints.ai_flags |= AI_PASSIVE;
410
411 /* Obtain local/remote address information */
412 if ((rc = getaddrinfo(host, port, &hints, passive ? &local : &remote))) {
413 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s.\n",
414 layer4_name(l4type),
415 host? host : (passive? "[loopback]" : "[localhost]"),
416 port, gai_strerror(rc));
417 return -E_ADDRESS_LOOKUP;
418 }
419
420 /* Iterate over all src/dst combination, exhausting dst first */
421 for (src = local, dst = remote; src != NULL || dst != NULL; /* no op */ ) {
422 if (src && dst && src->ai_family == AF_INET
423 && dst->ai_family == AF_INET6)
424 goto get_next_dst; /* v4 -> v6 is not possible */
425
426 sockfd = socket(src ? src->ai_family : dst->ai_family,
427 socktype, l4type);
428 if (sockfd < 0)
429 goto get_next_dst;
430
431 /*
432 * Set those options that need to be set before establishing
433 * the connection. Reuse the address on passive (listening)
434 * sockets to avoid failure on restart.
435 */
436 if (passive && setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
437 &on, sizeof(on)) == -1) {
438 PARA_ERROR_LOG("can not set SO_REUSEADDR: %s\n",
439 strerror(errno));
440 return -ERRNO_TO_PARA_ERROR(errno);
441 }
442 flowopt_setopts(sockfd, fo);
443
444 if (src) {
445 if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
446 close(sockfd);
447 goto get_next_src;
448 }
449 if (!dst) /* bind-only completed successfully */
450 break;
451 }
452
453 if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
454 break; /* connection completed successfully */
455 close(sockfd);
456 get_next_dst:
457 if (dst && (dst = dst->ai_next))
458 continue;
459 get_next_src:
460 if (src && (src = src->ai_next)) /* restart inner loop */
461 dst = remote;
462 }
463 if (local)
464 freeaddrinfo(local);
465 if (remote)
466 freeaddrinfo(remote);
467 flowopt_cleanup(fo);
468
469 if (src == NULL && dst == NULL) {
470 PARA_ERROR_LOG("can not create %s socket %s#%s.\n",
471 layer4_name(l4type), host? host : (passive?
472 "[loopback]" : "[localhost]"), port);
473 return -ERRNO_TO_PARA_ERROR(errno);
474 }
475 return sockfd;
476 }
477
478 /**
479 * Create a passive / listening socket.
480 *
481 * \param l3type The network-layer type (\p AF_xxx).
482 * \param l4type The transport-layer type (\p IPPROTO_xxx).
483 * \param port The decimal port number to listen on.
484 *
485 * \return Positive integer (socket descriptor) on success, negative value
486 * otherwise.
487 *
488 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
489 */
490 int para_listen(unsigned l3type, unsigned l4type, unsigned short port)
491 {
492 int ret, fd = makesock(l3type, l4type, 1, NULL, port, NULL);
493
494 if (fd > 0) {
495 ret = listen(fd, BACKLOG);
496 if (ret < 0) {
497 close(fd);
498 return -ERRNO_TO_PARA_ERROR(errno);
499 }
500 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
501 layer4_name(l4type), port, fd);
502 }
503 return fd;
504 }
505
506 /**
507 * Determine IPv4/v6 socket address length.
508 * \param sa Container of IPv4 or IPv6 address.
509 * \return Address-family dependent address length.
510 */
511 static socklen_t salen(const struct sockaddr *sa)
512 {
513 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
514
515 return sa->sa_family == AF_INET6
516 ? sizeof(struct sockaddr_in6)
517 : sizeof(struct sockaddr_in);
518 }
519
520 /**
521 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
522 * \param ss Container of IPv4/6 address.
523 * \return Pointer to normalized address (may be static storage).
524 *
525 * \sa RFC 3493
526 */
527 static const struct sockaddr *
528 normalize_ip_address(const struct sockaddr_storage *ss)
529 {
530 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
531
532 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
533
534 if (ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr)) {
535 static struct sockaddr_in ia;
536
537 ia.sin_family = AF_INET;
538 ia.sin_port = ia6->sin6_port;
539 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
540 return (const struct sockaddr *)&ia;
541 }
542 return (const struct sockaddr *)ss;
543 }
544
545 /**
546 * Print numeric host and port number (beware - uses static char).
547 *
548 * \param sa The IPv4/IPv6 socket address to use.
549 *
550 * \sa getnameinfo(3), services(5), nsswitch.conf(5)
551 */
552 static char *host_and_port(const struct sockaddr_storage *ss)
553 {
554 const struct sockaddr *sa = normalize_ip_address(ss);
555 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
556 static char output[sizeof(hbuf) + sizeof(sbuf) + 2];
557 int ret;
558
559 ret = getnameinfo(sa, salen(sa),
560 hbuf, sizeof(hbuf),
561 sbuf, sizeof(sbuf),
562 NI_NUMERICHOST);
563 if (ret == 0) {
564 snprintf(output, sizeof(output), "%s#%s", hbuf, sbuf);
565 } else {
566 snprintf(output, sizeof(output), "(unknown)");
567 PARA_WARNING_LOG("hostname lookup error (%s).\n",
568 gai_strerror(ret));
569 }
570 return output;
571 }
572
573 /**
574 * Look up the local or remote side of a connected socket structure.
575 *
576 * \param fd The socket descriptor of the connected socket.
577 * \param getname Either \p getsockname() for local, or \p getpeername() for
578 * remote side.
579 *
580 * \return A static character string identifying hostname and port of the
581 * chosen side.
582 *
583 * \sa getsockname(2), getpeername(2).
584 */
585 static char *__get_sock_name(int fd, int (*getname)(int, struct sockaddr*,
586 socklen_t *))
587 {
588 struct sockaddr_storage ss;
589 socklen_t sslen = sizeof(ss);
590
591 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
592 static char *dont_know = "(don't know)";
593 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
594 fd, strerror(errno));
595 return dont_know;
596 }
597 return host_and_port(&ss);
598 }
599
600 /**
601 * Look up the local side of a connected socket structure.
602 *
603 * \param sockfd The file descriptor of the socket.
604 *
605 * \return A pointer to a static buffer containing hostname an port. This
606 * buffer must not be freed by the caller.
607 *
608 * \sa remote_name().
609 */
610 char *local_name(int sockfd)
611 {
612 return __get_sock_name(sockfd, getsockname);
613 }
614
615 /**
616 * Look up the remote side of a connected socket structure.
617 *
618 * \param sockfd The file descriptor of the socket.
619 *
620 * \return Analogous to the return value of \ref local_name() but for the
621 * remote side.
622 *
623 * \sa local_name().
624 */
625 char *remote_name(int sockfd)
626 {
627 return __get_sock_name(sockfd, getpeername);
628 }
629
630 /**
631 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
632 * \param ss Container of IPv4/6 address
633 * \return Extracted IPv4 address (different from 0) or 0 if unsuccessful.
634 *
635 * \sa RFC 3493
636 */
637 struct in_addr extract_v4_addr(const struct sockaddr_storage *ss)
638 {
639 struct in_addr ia = {.s_addr = 0};
640 const struct sockaddr *sa = normalize_ip_address(ss);
641
642 if (sa->sa_family == AF_INET)
643 ia = ((struct sockaddr_in *)sa)->sin_addr;
644 return ia;
645 }
646
647 /**
648 * Send a binary buffer.
649 *
650 * \param fd The file descriptor.
651 * \param buf The buffer to be sent.
652 * \param len The length of \a buf.
653 *
654 * Send out the buffer and try to resend the remaining part in case of short
655 * writes.
656 *
657 * \return Standard.
658 */
659 int send_bin_buffer(int fd, const char *buf, size_t len)
660 {
661 if (!len)
662 PARA_CRIT_LOG("len == 0\n");
663 return write_all(fd, buf, &len);
664 }
665
666 /**
667 * Send a \p NULL-terminated buffer.
668 *
669 * \param fd The file descriptor.
670 * \param buf The null-terminated buffer to be send.
671 *
672 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
673 *
674 * \return Standard.
675 */
676 int send_buffer(int fd, const char *buf)
677 {
678 return send_bin_buffer(fd, buf, strlen(buf));
679 }
680
681 /**
682 * Send a buffer given by a format string.
683 *
684 * \param fd The file descriptor.
685 * \param fmt A format string.
686 *
687 * \return Standard.
688 */
689 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
690 {
691 char *msg;
692 int ret;
693
694 PARA_VSPRINTF(fmt, msg);
695 ret = send_buffer(fd, msg);
696 free(msg);
697 return ret;
698 }
699
700 /**
701 * Receive data from a file descriptor.
702 *
703 * \param fd The file descriptor.
704 * \param buf The buffer to write the data to.
705 * \param size The size of \a buf.
706 *
707 * Receive at most \a size bytes from file descriptor \a fd.
708 *
709 * \return The number of bytes received on success, negative on errors, zero if
710 * the peer has performed an orderly shutdown.
711 *
712 * \sa recv(2).
713 */
714 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
715 {
716 ssize_t n;
717
718 n = recv(fd, buf, size, 0);
719 if (n == -1)
720 return -ERRNO_TO_PARA_ERROR(errno);
721 return n;
722 }
723
724 /**
725 * Receive and write terminating NULL byte.
726 *
727 * \param fd The file descriptor.
728 * \param buf The buffer to write the data to.
729 * \param size The size of \a buf.
730 *
731 * Read at most \a size - 1 bytes from file descriptor \a fd and
732 * write a NULL byte at the end of the received data.
733 *
734 * \return The return value of the underlying call to \a recv_bin_buffer().
735 *
736 * \sa recv_bin_buffer()
737 */
738 int recv_buffer(int fd, char *buf, size_t size)
739 {
740 int n;
741
742 assert(size);
743 n = recv_bin_buffer(fd, buf, size - 1);
744 if (n >= 0)
745 buf[n] = '\0';
746 else
747 *buf = '\0';
748 return n;
749 }
750
751 /**
752 * Wrapper around the accept system call.
753 *
754 * \param fd The listening socket.
755 * \param addr Structure which is filled in with the address of the peer socket.
756 * \param size Should contain the size of the structure pointed to by \a addr.
757 *
758 * Accept incoming connections on \a addr. Retry if interrupted.
759 *
760 * \return The new file descriptor on success, negative on errors.
761 *
762 * \sa accept(2).
763 */
764 int para_accept(int fd, void *addr, socklen_t size)
765 {
766 int new_fd;
767
768 do
769 new_fd = accept(fd, (struct sockaddr *) addr, &size);
770 while (new_fd < 0 && errno == EINTR);
771 return new_fd < 0? -ERRNO_TO_PARA_ERROR(errno) : new_fd;
772 }
773
774 /**
775 * Probe the list of DCCP CCIDs supported locally by the host.
776 * \param ccids Array to be filled in.
777 * \param nccids Length of \a ccids.
778 * \return Pointer to \a ccids, NULL on failure.
779 *
780 * NB: This feature is only available on Linux > 2.6.30; on older kernels
781 * ENOPROTOOPT ("Protocol not available") will be returned.
782 */
783 const uint8_t *dccp_available_ccids(uint8_t *ccids, uint8_t *nccids)
784 {
785 int fd = makesock(AF_UNSPEC, IPPROTO_DCCP, 1, NULL, 0, NULL);
786
787 if (fd < 0)
788 return NULL;
789
790 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
791 ccids, (socklen_t *)nccids) < 0) {
792 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
793 strerror(errno));
794 *nccids = 0;
795 }
796 close(fd);
797
798 return *nccids ? ccids : NULL;
799 }
800
801 /**
802 * Prepare a structure for \p AF_UNIX socket addresses.
803 *
804 * \param u Pointer to the struct to be prepared.
805 * \param name The socket pathname.
806 *
807 * This just copies \a name to the sun_path component of \a u.
808 *
809 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
810 * than \p UNIX_PATH_MAX.
811 */
812 static int init_unix_addr(struct sockaddr_un *u, const char *name)
813 {
814 if (strlen(name) >= UNIX_PATH_MAX)
815 return -E_NAME_TOO_LONG;
816 memset(u->sun_path, 0, UNIX_PATH_MAX);
817 u->sun_family = PF_UNIX;
818 strcpy(u->sun_path, name);
819 return 1;
820 }
821
822 /**
823 * Prepare, create, and bind a socket for local communication.
824 *
825 * \param name The socket pathname.
826 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
827 * \param mode The desired mode of the socket.
828 *
829 * This function creates a local socket for sequenced, reliable,
830 * two-way, connection-based byte streams.
831 *
832 * \return The file descriptor, on success, negative on errors.
833 *
834 * \sa socket(2)
835 * \sa bind(2)
836 * \sa chmod(2)
837 */
838 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
839 mode_t mode)
840 {
841 int fd, ret;
842
843 ret = init_unix_addr(unix_addr, name);
844 if (ret < 0)
845 return ret;
846 ret = socket(PF_UNIX, SOCK_STREAM, 0);
847 if (ret < 0)
848 return -ERRNO_TO_PARA_ERROR(errno);
849 fd = ret;
850 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
851 if (ret < 0) {
852 ret = -ERRNO_TO_PARA_ERROR(errno);
853 goto err;
854 }
855 ret = -E_CHMOD;
856 if (chmod(name, mode) < 0)
857 goto err;
858 return fd;
859 err:
860 close(fd);
861 return ret;
862 }
863
864 /**
865 * Prepare, create, and connect to a Unix domain socket for local communication.
866 *
867 * \param name The socket pathname.
868 *
869 * This function creates a local socket for sequenced, reliable, two-way,
870 * connection-based byte streams.
871 *
872 * \return The file descriptor, on success, negative on errors.
873 *
874 * \sa create_local_socket(), unix(7), connect(2).
875 */
876 int create_remote_socket(const char *name)
877 {
878 struct sockaddr_un unix_addr;
879 int fd, ret;
880
881 ret = init_unix_addr(&unix_addr, name);
882 if (ret < 0)
883 return ret;
884 fd = socket(PF_UNIX, SOCK_STREAM, 0);
885 if (fd < 0)
886 return -ERRNO_TO_PARA_ERROR(errno);
887 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) == -1) {
888 ret = -ERRNO_TO_PARA_ERROR(errno);
889 goto err;
890 }
891 return fd;
892 err:
893 close(fd);
894 return ret;
895 }
896
897 #ifndef HAVE_UCRED
898 ssize_t send_cred_buffer(int sock, char *buf)
899 {
900 return send_buffer(sock, buf);
901 }
902 int recv_cred_buffer(int fd, char *buf, size_t size)
903 {
904 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
905 }
906 #else /* HAVE_UCRED */
907 /**
908 * Send \p NULL-terminated buffer and Unix credentials of the current process.
909 *
910 * \param sock The socket file descriptor.
911 * \param buf The buffer to be sent.
912 *
913 * \return On success, this call returns the number of characters sent. On
914 * error, \p -E_SENDMSG is returned.
915 *
916 * \sa sendmsg(2), okir's Black Hats Manual.
917 */
918 ssize_t send_cred_buffer(int sock, char *buf)
919 {
920 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
921 struct msghdr msg;
922 struct cmsghdr *cmsg;
923 static struct iovec iov;
924 struct ucred c;
925 int ret;
926
927 /* Response data */
928 iov.iov_base = buf;
929 iov.iov_len = strlen(buf);
930 c.pid = getpid();
931 c.uid = getuid();
932 c.gid = getgid();
933 /* compose the message */
934 memset(&msg, 0, sizeof(msg));
935 msg.msg_iov = &iov;
936 msg.msg_iovlen = 1;
937 msg.msg_control = control;
938 msg.msg_controllen = sizeof(control);
939 /* attach the ucred struct */
940 cmsg = CMSG_FIRSTHDR(&msg);
941 cmsg->cmsg_level = SOL_SOCKET;
942 cmsg->cmsg_type = SCM_CREDENTIALS;
943 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
944 *(struct ucred *)CMSG_DATA(cmsg) = c;
945 msg.msg_controllen = cmsg->cmsg_len;
946 ret = sendmsg(sock, &msg, 0);
947 if (ret < 0)
948 ret = -E_SENDMSG;
949 return ret;
950 }
951
952 static void dispose_fds(int *fds, unsigned num)
953 {
954 int i;
955
956 for (i = 0; i < num; i++)
957 close(fds[i]);
958 }
959
960 /**
961 * Receive a buffer and the Unix credentials of the sending process.
962 *
963 * \param fd the socket file descriptor.
964 * \param buf the buffer to store the message.
965 * \param size the size of \a buffer.
966 *
967 * \return negative on errors, the user id on success.
968 *
969 * \sa recvmsg(2), okir's Black Hats Manual.
970 */
971 int recv_cred_buffer(int fd, char *buf, size_t size)
972 {
973 char control[255];
974 struct msghdr msg;
975 struct cmsghdr *cmsg;
976 struct iovec iov;
977 int result = 0;
978 int yes = 1;
979 struct ucred cred;
980
981 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
982 memset(&msg, 0, sizeof(msg));
983 memset(buf, 0, size);
984 iov.iov_base = buf;
985 iov.iov_len = size;
986 msg.msg_iov = &iov;
987 msg.msg_iovlen = 1;
988 msg.msg_control = control;
989 msg.msg_controllen = sizeof(control);
990 if (recvmsg(fd, &msg, 0) < 0)
991 return -E_RECVMSG;
992 result = -E_SCM_CREDENTIALS;
993 cmsg = CMSG_FIRSTHDR(&msg);
994 while (cmsg) {
995 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
996 == SCM_CREDENTIALS) {
997 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
998 result = cred.uid;
999 } else
1000 if (cmsg->cmsg_level == SOL_SOCKET
1001 && cmsg->cmsg_type == SCM_RIGHTS) {
1002 dispose_fds((int *) CMSG_DATA(cmsg),
1003 (cmsg->cmsg_len - CMSG_LEN(0))
1004 / sizeof(int));
1005 }
1006 cmsg = CMSG_NXTHDR(&msg, cmsg);
1007 }
1008 return result;
1009 }
1010 #endif /* HAVE_UCRED */
1011
1012 /**
1013 * Receive a buffer and check for a pattern.
1014 *
1015 * \param fd The file descriptor to receive from.
1016 * \param pattern The expected pattern.
1017 * \param bufsize The size of the internal buffer.
1018 *
1019 * \return Positive if \a pattern was received, negative otherwise.
1020 *
1021 * This function tries to receive at most \a bufsize bytes from file descriptor
1022 * \a fd. If at least \p strlen(\a pattern) bytes were received, the beginning
1023 * of the received buffer is compared with \a pattern, ignoring case.
1024 *
1025 * \sa recv_buffer(), \sa strncasecmp(3).
1026 */
1027 int recv_pattern(int fd, const char *pattern, size_t bufsize)
1028 {
1029 size_t len = strlen(pattern);
1030 char *buf = para_malloc(bufsize + 1);
1031 int ret = -E_RECV_PATTERN, n = recv_buffer(fd, buf, bufsize + 1);
1032
1033 if (n < len)
1034 goto out;
1035 if (strncasecmp(buf, pattern, len))
1036 goto out;
1037 ret = 1;
1038 out:
1039 if (ret < 0) {
1040 PARA_NOTICE_LOG("did not receive pattern '%s'\n", pattern);
1041 if (n > 0)
1042 PARA_NOTICE_LOG("recvd %d bytes: %s\n", n, buf);
1043 else if (n < 0)
1044 PARA_NOTICE_LOG("%s\n", para_strerror(-n));
1045 }
1046 free(buf);
1047 return ret;
1048 }