NEWS update
[paraslash.git] / net.c
1 /*
2 * Copyright (C) 2005-2010 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 \a 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 l4type The layer-4 type (\p IPPROTO_xxx).
355 * \param passive Whether this is a passive (1) or active (0) socket.
356 * \param host Remote or local hostname or IPv/6 address string.
357 * \param port_number Decimal port number.
358 * \param fo Socket options to be set before making the connection.
359 *
360 * This creates a ready-made IPv4/v6 socket structure after looking up the
361 * necessary parameters. The interpretation of \a host depends on the value of
362 * \a passive:
363 * - on a passive socket host is interpreted as an interface IPv4/6 address
364 * (can be left NULL);
365 * - on an active socket, \a host is the peer DNS name or IPv4/6 address
366 * to connect to;
367 * - \a port_number is in either case the numeric port number (not service
368 * string).
369 *
370 * Furthermore, bind(2) is called on passive sockets, and connect(2) on active
371 * sockets. The algorithm tries all possible address combinations until it
372 * succeeds. If \a fo is supplied, options are set and cleanup is performed.
373 *
374 * \return This function returns 1 on success and \a -E_ADDRESS_LOOKUP when no
375 * matching connection could be set up (with details in the error log).
376 *
377 * \sa ipv6(7), getaddrinfo(3), bind(2), connect(2).
378 */
379 int makesock(unsigned l4type, bool passive,
380 const char *host, uint16_t port_number,
381 struct flowopts *fo)
382 {
383 struct addrinfo *local = NULL, *src,
384 *remote = NULL, *dst, hints;
385 unsigned int l3type = AF_UNSPEC;
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 * Reuse the address on passive sockets to avoid failure on
433 * restart (protocols using listen()) and when creating
434 * multiple listener instances (UDP multicast).
435 */
436 if (passive && setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
437 &on, sizeof(on)) == -1) {
438 rc = errno;
439 close(sockfd);
440 PARA_ERROR_LOG("can not set SO_REUSEADDR: %s\n",
441 strerror(rc));
442 return -ERRNO_TO_PARA_ERROR(rc);
443 }
444 flowopt_setopts(sockfd, fo);
445
446 if (src) {
447 if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
448 close(sockfd);
449 goto get_next_src;
450 }
451 if (!dst) /* bind-only completed successfully */
452 break;
453 }
454
455 if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
456 break; /* connection completed successfully */
457 close(sockfd);
458 get_next_dst:
459 if (dst && (dst = dst->ai_next))
460 continue;
461 get_next_src:
462 if (src && (src = src->ai_next)) /* restart inner loop */
463 dst = remote;
464 }
465 if (local)
466 freeaddrinfo(local);
467 if (remote)
468 freeaddrinfo(remote);
469 flowopt_cleanup(fo);
470
471 if (src == NULL && dst == NULL) {
472 rc = errno;
473 PARA_ERROR_LOG("can not create %s socket %s#%s.\n",
474 layer4_name(l4type), host? host : (passive?
475 "[loopback]" : "[localhost]"), port);
476 return -ERRNO_TO_PARA_ERROR(rc);
477 }
478 return sockfd;
479 }
480
481 /**
482 * Create a passive / listening socket.
483 *
484 * \param l4type The transport-layer type (\p IPPROTO_xxx).
485 * \param port The decimal port number to listen on.
486 * \param fo Flowopts (if any) to set before starting to listen.
487 *
488 * \return Positive integer (socket descriptor) on success, negative value
489 * otherwise.
490 *
491 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
492 */
493 int para_listen(unsigned l4type, uint16_t port, struct flowopts *fo)
494 {
495 int ret, fd = makesock(l4type, 1, NULL, port, fo);
496
497 if (fd > 0) {
498 ret = listen(fd, BACKLOG);
499 if (ret < 0) {
500 ret = errno;
501 close(fd);
502 return -ERRNO_TO_PARA_ERROR(ret);
503 }
504 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
505 layer4_name(l4type), port, fd);
506 }
507 return fd;
508 }
509
510 /**
511 * Determine IPv4/v6 socket address length.
512 * \param sa Container of IPv4 or IPv6 address.
513 * \return Address-family dependent address length.
514 */
515 static socklen_t salen(const struct sockaddr *sa)
516 {
517 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
518
519 return sa->sa_family == AF_INET6
520 ? sizeof(struct sockaddr_in6)
521 : sizeof(struct sockaddr_in);
522 }
523
524 /** True if @ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
525 static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
526 {
527 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
528
529 return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
530 }
531
532 /**
533 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
534 * \param ss Container of IPv4/6 address.
535 * \return Pointer to normalized address (may be static storage).
536 *
537 * \sa RFC 3493
538 */
539 static const struct sockaddr *
540 normalize_ip_address(const struct sockaddr_storage *ss)
541 {
542 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
543
544 if (SS_IS_ADDR_V4MAPPED(ss)) {
545 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
546 static struct sockaddr_in ia;
547
548 ia.sin_family = AF_INET;
549 ia.sin_port = ia6->sin6_port;
550 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
551 return (const struct sockaddr *)&ia;
552 }
553 return (const struct sockaddr *)ss;
554 }
555
556 /**
557 * Generic/fallback MTU values
558 *
559 * These are taken from RFC 1122, RFC 2460, and RFC 5405.
560 * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
561 * to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
562 * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
563 * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
564 * UDP senders should use the respective minimum values of EMTU_S.
565 */
566 static inline int generic_mtu(const int af_type)
567 {
568 return af_type == AF_INET6 ? 1280 : 576;
569 }
570
571 /** Crude approximation of IP header overhead - neglecting options. */
572 static inline int estimated_header_overhead(const int af_type)
573 {
574 return af_type == AF_INET6 ? 40 : 20;
575 }
576
577 /**
578 * Maximum transport-layer message size (MMS_S) as per RFC 1122, 3.3.3
579 * Socket must be connected.
580 */
581 int generic_max_transport_msg_size(int sockfd)
582 {
583 struct sockaddr_storage ss;
584 socklen_t sslen = sizeof(ss);
585 int af_type = AF_INET;
586
587 if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
588 PARA_ERROR_LOG("can not determine remote address type: %s\n",
589 strerror(errno));
590 } else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
591 af_type = ss.ss_family;
592 }
593 return generic_mtu(af_type) - estimated_header_overhead(af_type);
594 }
595
596 /**
597 * Print numeric host and port number (beware - uses static char).
598 *
599 * \param sa The IPv4/IPv6 socket address to use.
600 *
601 * \return Host string in numeric host:port format, \sa parse_url().
602 * \sa getnameinfo(3), services(5), nsswitch.conf(5)
603 */
604 static char *host_and_port(const struct sockaddr_storage *ss)
605 {
606 const struct sockaddr *sa = normalize_ip_address(ss);
607 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
608 static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
609 int ret;
610
611 ret = getnameinfo(sa, salen(sa),
612 hbuf, sizeof(hbuf),
613 sbuf, sizeof(sbuf),
614 NI_NUMERICHOST | NI_NUMERICSERV);
615 if (ret) {
616 snprintf(output, sizeof(output), "(unknown)");
617 PARA_WARNING_LOG("hostname lookup error (%s).\n",
618 gai_strerror(ret));
619 } else if (sa->sa_family == AF_INET6) {
620 snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
621 } else {
622 snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
623 }
624 return output;
625 }
626
627 /**
628 * Look up the local or remote side of a connected socket structure.
629 *
630 * \param fd The socket descriptor of the connected socket.
631 * \param getname Either \p getsockname() for local, or \p getpeername() for
632 * remote side.
633 *
634 * \return A static character string identifying hostname and port of the
635 * chosen side.
636 *
637 * \sa getsockname(2), getpeername(2).
638 */
639 static char *__get_sock_name(int fd, int (*getname)(int, struct sockaddr*,
640 socklen_t *))
641 {
642 struct sockaddr_storage ss;
643 socklen_t sslen = sizeof(ss);
644
645 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
646 static char *dont_know = "(don't know)";
647 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
648 fd, strerror(errno));
649 return dont_know;
650 }
651 return host_and_port(&ss);
652 }
653
654 /**
655 * Look up the local side of a connected socket structure.
656 *
657 * \param sockfd The file descriptor of the socket.
658 *
659 * \return A pointer to a static buffer containing hostname an port. This
660 * buffer must not be freed by the caller.
661 *
662 * \sa remote_name().
663 */
664 char *local_name(int sockfd)
665 {
666 return __get_sock_name(sockfd, getsockname);
667 }
668
669 /**
670 * Look up the remote side of a connected socket structure.
671 *
672 * \param sockfd The file descriptor of the socket.
673 *
674 * \return Analogous to the return value of \ref local_name() but for the
675 * remote side.
676 *
677 * \sa local_name().
678 */
679 char *remote_name(int sockfd)
680 {
681 return __get_sock_name(sockfd, getpeername);
682 }
683
684 /**
685 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
686 * \param ss Container of IPv4/6 address
687 * \return Extracted IPv4 address (different from 0) or 0 if unsuccessful.
688 *
689 * \sa RFC 3493
690 */
691 struct in_addr extract_v4_addr(const struct sockaddr_storage *ss)
692 {
693 struct in_addr ia = {.s_addr = 0};
694 const struct sockaddr *sa = normalize_ip_address(ss);
695
696 if (sa->sa_family == AF_INET)
697 ia = ((struct sockaddr_in *)sa)->sin_addr;
698 return ia;
699 }
700
701 /**
702 * Send a binary buffer.
703 *
704 * \param fd The file descriptor.
705 * \param buf The buffer to be sent.
706 * \param len The length of \a buf.
707 *
708 * Send out the buffer and try to resend the remaining part in case of short
709 * writes.
710 *
711 * \return Standard.
712 */
713 int send_bin_buffer(int fd, const char *buf, size_t len)
714 {
715 if (!len)
716 PARA_CRIT_LOG("len == 0\n");
717 return write_all(fd, buf, &len);
718 }
719
720 /**
721 * Send a \p NULL-terminated buffer.
722 *
723 * \param fd The file descriptor.
724 * \param buf The null-terminated buffer to be send.
725 *
726 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
727 *
728 * \return Standard.
729 */
730 int send_buffer(int fd, const char *buf)
731 {
732 return send_bin_buffer(fd, buf, strlen(buf));
733 }
734
735 /**
736 * Send a buffer given by a format string.
737 *
738 * \param fd The file descriptor.
739 * \param fmt A format string.
740 *
741 * \return Standard.
742 */
743 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
744 {
745 char *msg;
746 int ret;
747
748 PARA_VSPRINTF(fmt, msg);
749 ret = send_buffer(fd, msg);
750 free(msg);
751 return ret;
752 }
753
754 /**
755 * Receive data from a file descriptor.
756 *
757 * \param fd The file descriptor.
758 * \param buf The buffer to write the data to.
759 * \param size The size of \a buf.
760 *
761 * Receive at most \a size bytes from file descriptor \a fd.
762 *
763 * \return The number of bytes received on success, negative on errors, zero if
764 * the peer has performed an orderly shutdown.
765 *
766 * \sa recv(2).
767 */
768 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
769 {
770 ssize_t n;
771
772 n = recv(fd, buf, size, 0);
773 if (n == -1)
774 return -ERRNO_TO_PARA_ERROR(errno);
775 return n;
776 }
777
778 /**
779 * Receive and write terminating NULL byte.
780 *
781 * \param fd The file descriptor.
782 * \param buf The buffer to write the data to.
783 * \param size The size of \a buf.
784 *
785 * Read at most \a size - 1 bytes from file descriptor \a fd and
786 * write a NULL byte at the end of the received data.
787 *
788 * \return The return value of the underlying call to \a recv_bin_buffer().
789 *
790 * \sa recv_bin_buffer()
791 */
792 int recv_buffer(int fd, char *buf, size_t size)
793 {
794 int n;
795
796 assert(size);
797 n = recv_bin_buffer(fd, buf, size - 1);
798 if (n >= 0)
799 buf[n] = '\0';
800 else
801 *buf = '\0';
802 return n;
803 }
804
805 /**
806 * Wrapper around the accept system call.
807 *
808 * \param fd The listening socket.
809 * \param rfds An optional fd_set pointer.
810 * \param addr Structure which is filled in with the address of the peer socket.
811 * \param size Should contain the size of the structure pointed to by \a addr.
812 * \param new_fd Result pointer.
813 *
814 * Accept incoming connections on \a addr, retry if interrupted. If \a rfds is
815 * not \p NULL, return 0 if \a fd is not set in \a rfds without calling accept().
816 *
817 * \return Negative on errors, zero if no connections are present to be accepted,
818 * one otherwise.
819 *
820 * \sa accept(2).
821 */
822 int para_accept(int fd, fd_set *rfds, void *addr, socklen_t size, int *new_fd)
823 {
824 int ret;
825
826 if (rfds && !FD_ISSET(fd, rfds))
827 return 0;
828 do
829 ret = accept(fd, (struct sockaddr *) addr, &size);
830 while (ret < 0 && errno == EINTR);
831
832 if (ret >= 0) {
833 *new_fd = ret;
834 return 1;
835 }
836 if (errno == EAGAIN || errno == EWOULDBLOCK)
837 return 0;
838 return -ERRNO_TO_PARA_ERROR(errno);
839 }
840
841 /**
842 * Probe the list of DCCP CCIDs configured on this host.
843 * \param ccid_array Pointer to return statically allocated array in.
844 * \return Number of elements returned in \a ccid_array or error.
845 *
846 * NB: This feature is only available on Linux > 2.6.30; on older kernels
847 * ENOPROTOOPT ("Protocol not available") will be returned.
848 */
849 int dccp_available_ccids(uint8_t **ccid_array)
850 {
851 static uint8_t ccids[DCCP_MAX_HOST_CCIDS];
852 socklen_t nccids = sizeof(ccids);
853 int ret, fd;
854
855 ret = fd = makesock(IPPROTO_DCCP, 1, NULL, 0, NULL);
856 if (ret < 0)
857 return ret;
858
859 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
860 ccids, &nccids) < 0) {
861 ret = errno;
862 close(fd);
863 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
864 strerror(ret));
865 return -ERRNO_TO_PARA_ERROR(ret);
866 }
867
868 close(fd);
869 *ccid_array = ccids;
870 return nccids;
871 }
872
873 /**
874 * Prepare a structure for \p AF_UNIX socket addresses.
875 *
876 * \param u Pointer to the struct to be prepared.
877 * \param name The socket pathname.
878 *
879 * This just copies \a name to the sun_path component of \a u.
880 *
881 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
882 * than \p UNIX_PATH_MAX.
883 */
884 static int init_unix_addr(struct sockaddr_un *u, const char *name)
885 {
886 if (strlen(name) >= UNIX_PATH_MAX)
887 return -E_NAME_TOO_LONG;
888 memset(u->sun_path, 0, UNIX_PATH_MAX);
889 u->sun_family = PF_UNIX;
890 strcpy(u->sun_path, name);
891 return 1;
892 }
893
894 /**
895 * Prepare, create, and bind a socket for local communication.
896 *
897 * \param name The socket pathname.
898 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
899 * \param mode The desired mode of the socket.
900 *
901 * This function creates a local socket for sequenced, reliable,
902 * two-way, connection-based byte streams.
903 *
904 * \return The file descriptor, on success, negative on errors.
905 *
906 * \sa socket(2)
907 * \sa bind(2)
908 * \sa chmod(2)
909 */
910 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
911 mode_t mode)
912 {
913 int fd, ret;
914
915 ret = init_unix_addr(unix_addr, name);
916 if (ret < 0)
917 return ret;
918 ret = socket(PF_UNIX, SOCK_STREAM, 0);
919 if (ret < 0)
920 return -ERRNO_TO_PARA_ERROR(errno);
921 fd = ret;
922 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
923 if (ret < 0) {
924 ret = -ERRNO_TO_PARA_ERROR(errno);
925 goto err;
926 }
927 ret = -E_CHMOD;
928 if (chmod(name, mode) < 0)
929 goto err;
930 return fd;
931 err:
932 close(fd);
933 return ret;
934 }
935
936 /**
937 * Prepare, create, and connect to a Unix domain socket for local communication.
938 *
939 * \param name The socket pathname.
940 *
941 * This function creates a local socket for sequenced, reliable, two-way,
942 * connection-based byte streams.
943 *
944 * \return The file descriptor, on success, negative on errors.
945 *
946 * \sa create_local_socket(), unix(7), connect(2).
947 */
948 int create_remote_socket(const char *name)
949 {
950 struct sockaddr_un unix_addr;
951 int fd, ret;
952
953 ret = init_unix_addr(&unix_addr, name);
954 if (ret < 0)
955 return ret;
956 fd = socket(PF_UNIX, SOCK_STREAM, 0);
957 if (fd < 0)
958 return -ERRNO_TO_PARA_ERROR(errno);
959 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) == -1) {
960 ret = -ERRNO_TO_PARA_ERROR(errno);
961 goto err;
962 }
963 return fd;
964 err:
965 close(fd);
966 return ret;
967 }
968
969 #ifndef HAVE_UCRED
970 ssize_t send_cred_buffer(int sock, char *buf)
971 {
972 return send_buffer(sock, buf);
973 }
974 int recv_cred_buffer(int fd, char *buf, size_t size)
975 {
976 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
977 }
978 #else /* HAVE_UCRED */
979 /**
980 * Send \p NULL-terminated buffer and Unix credentials of the current process.
981 *
982 * \param sock The socket file descriptor.
983 * \param buf The buffer to be sent.
984 *
985 * \return On success, this call returns the number of characters sent. On
986 * error, \p -E_SENDMSG is returned.
987 *
988 * \sa sendmsg(2), okir's Black Hats Manual.
989 */
990 ssize_t send_cred_buffer(int sock, char *buf)
991 {
992 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
993 struct msghdr msg;
994 struct cmsghdr *cmsg;
995 static struct iovec iov;
996 struct ucred c;
997 int ret;
998
999 /* Response data */
1000 iov.iov_base = buf;
1001 iov.iov_len = strlen(buf);
1002 c.pid = getpid();
1003 c.uid = getuid();
1004 c.gid = getgid();
1005 /* compose the message */
1006 memset(&msg, 0, sizeof(msg));
1007 msg.msg_iov = &iov;
1008 msg.msg_iovlen = 1;
1009 msg.msg_control = control;
1010 msg.msg_controllen = sizeof(control);
1011 /* attach the ucred struct */
1012 cmsg = CMSG_FIRSTHDR(&msg);
1013 cmsg->cmsg_level = SOL_SOCKET;
1014 cmsg->cmsg_type = SCM_CREDENTIALS;
1015 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
1016 *(struct ucred *)CMSG_DATA(cmsg) = c;
1017 msg.msg_controllen = cmsg->cmsg_len;
1018 ret = sendmsg(sock, &msg, 0);
1019 if (ret < 0)
1020 ret = -E_SENDMSG;
1021 return ret;
1022 }
1023
1024 static void dispose_fds(int *fds, unsigned num)
1025 {
1026 int i;
1027
1028 for (i = 0; i < num; i++)
1029 close(fds[i]);
1030 }
1031
1032 /**
1033 * Receive a buffer and the Unix credentials of the sending process.
1034 *
1035 * \param fd the socket file descriptor.
1036 * \param buf the buffer to store the message.
1037 * \param size the size of \a buffer.
1038 *
1039 * \return negative on errors, the user id on success.
1040 *
1041 * \sa recvmsg(2), okir's Black Hats Manual.
1042 */
1043 int recv_cred_buffer(int fd, char *buf, size_t size)
1044 {
1045 char control[255];
1046 struct msghdr msg;
1047 struct cmsghdr *cmsg;
1048 struct iovec iov;
1049 int result = 0;
1050 int yes = 1;
1051 struct ucred cred;
1052
1053 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
1054 memset(&msg, 0, sizeof(msg));
1055 memset(buf, 0, size);
1056 iov.iov_base = buf;
1057 iov.iov_len = size;
1058 msg.msg_iov = &iov;
1059 msg.msg_iovlen = 1;
1060 msg.msg_control = control;
1061 msg.msg_controllen = sizeof(control);
1062 if (recvmsg(fd, &msg, 0) < 0)
1063 return -E_RECVMSG;
1064 result = -E_SCM_CREDENTIALS;
1065 cmsg = CMSG_FIRSTHDR(&msg);
1066 while (cmsg) {
1067 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
1068 == SCM_CREDENTIALS) {
1069 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
1070 result = cred.uid;
1071 } else
1072 if (cmsg->cmsg_level == SOL_SOCKET
1073 && cmsg->cmsg_type == SCM_RIGHTS) {
1074 dispose_fds((int *) CMSG_DATA(cmsg),
1075 (cmsg->cmsg_len - CMSG_LEN(0))
1076 / sizeof(int));
1077 }
1078 cmsg = CMSG_NXTHDR(&msg, cmsg);
1079 }
1080 return result;
1081 }
1082 #endif /* HAVE_UCRED */