gui: Check only once for invalid key maps.
[paraslash.git] / net.c
1 /*
2 * Copyright (C) 2005-2011 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 = NULL, *remote = NULL,
384 *dst = NULL, 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 rc = -E_ADDRESS_LOOKUP;
418 goto out;
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 /*
433 * Reuse the address on passive sockets to avoid failure on
434 * restart (protocols using listen()) and when creating
435 * multiple listener instances (UDP multicast).
436 */
437 if (passive && setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
438 &on, sizeof(on)) == -1) {
439 rc = errno;
440 close(sockfd);
441 PARA_ERROR_LOG("can not set SO_REUSEADDR: %s\n",
442 strerror(rc));
443 rc = -ERRNO_TO_PARA_ERROR(rc);
444 break;
445 }
446 flowopt_setopts(sockfd, fo);
447
448 if (src) {
449 if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
450 close(sockfd);
451 goto get_next_src;
452 }
453 if (!dst) /* bind-only completed successfully */
454 break;
455 }
456
457 if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
458 break; /* connection completed successfully */
459 close(sockfd);
460 get_next_dst:
461 if (dst && (dst = dst->ai_next))
462 continue;
463 get_next_src:
464 if (src && (src = src->ai_next)) /* restart inner loop */
465 dst = remote;
466 }
467 out:
468 if (local)
469 freeaddrinfo(local);
470 if (remote)
471 freeaddrinfo(remote);
472 flowopt_cleanup(fo);
473
474 if (src == NULL && dst == NULL) {
475 if (rc >= 0)
476 rc = -E_MAKESOCK;
477 PARA_ERROR_LOG("can not create %s socket %s#%s.\n",
478 layer4_name(l4type), host? host : (passive?
479 "[loopback]" : "[localhost]"), port);
480 return rc;
481 }
482 return sockfd;
483 }
484
485 /**
486 * Create a passive / listening socket.
487 *
488 * \param l4type The transport-layer type (\p IPPROTO_xxx).
489 * \param port The decimal port number to listen on.
490 * \param fo Flowopts (if any) to set before starting to listen.
491 *
492 * \return Positive integer (socket descriptor) on success, negative value
493 * otherwise.
494 *
495 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
496 */
497 int para_listen(unsigned l4type, uint16_t port, struct flowopts *fo)
498 {
499 int ret, fd = makesock(l4type, 1, NULL, port, fo);
500
501 if (fd > 0) {
502 ret = listen(fd, BACKLOG);
503 if (ret < 0) {
504 ret = errno;
505 close(fd);
506 return -ERRNO_TO_PARA_ERROR(ret);
507 }
508 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
509 layer4_name(l4type), port, fd);
510 }
511 return fd;
512 }
513
514 /**
515 * Determine IPv4/v6 socket address length.
516 * \param sa Container of IPv4 or IPv6 address.
517 * \return Address-family dependent address length.
518 */
519 static socklen_t salen(const struct sockaddr *sa)
520 {
521 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
522
523 return sa->sa_family == AF_INET6
524 ? sizeof(struct sockaddr_in6)
525 : sizeof(struct sockaddr_in);
526 }
527
528 /** True if @ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
529 static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
530 {
531 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
532
533 return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
534 }
535
536 /**
537 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
538 * \param ss Container of IPv4/6 address.
539 * \return Pointer to normalized address (may be static storage).
540 *
541 * \sa RFC 3493
542 */
543 static const struct sockaddr *
544 normalize_ip_address(const struct sockaddr_storage *ss)
545 {
546 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
547
548 if (SS_IS_ADDR_V4MAPPED(ss)) {
549 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
550 static struct sockaddr_in ia;
551
552 ia.sin_family = AF_INET;
553 ia.sin_port = ia6->sin6_port;
554 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
555 return (const struct sockaddr *)&ia;
556 }
557 return (const struct sockaddr *)ss;
558 }
559
560 /**
561 * Generic/fallback MTU values
562 *
563 * These are taken from RFC 1122, RFC 2460, and RFC 5405.
564 * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
565 * to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
566 * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
567 * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
568 * UDP senders should use the respective minimum values of EMTU_S.
569 */
570 static inline int generic_mtu(const int af_type)
571 {
572 return af_type == AF_INET6 ? 1280 : 576;
573 }
574
575 /** Crude approximation of IP header overhead - neglecting options. */
576 static inline int estimated_header_overhead(const int af_type)
577 {
578 return af_type == AF_INET6 ? 40 : 20;
579 }
580
581 /**
582 * Maximum transport-layer message size (MMS_S) as per RFC 1122, 3.3.3
583 * Socket must be connected.
584 */
585 int generic_max_transport_msg_size(int sockfd)
586 {
587 struct sockaddr_storage ss;
588 socklen_t sslen = sizeof(ss);
589 int af_type = AF_INET;
590
591 if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
592 PARA_ERROR_LOG("can not determine remote address type: %s\n",
593 strerror(errno));
594 } else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
595 af_type = ss.ss_family;
596 }
597 return generic_mtu(af_type) - estimated_header_overhead(af_type);
598 }
599
600 /**
601 * Print numeric host and port number (beware - uses static char).
602 *
603 * \param sa The IPv4/IPv6 socket address to use.
604 *
605 * \return Host string in numeric host:port format, \sa parse_url().
606 * \sa getnameinfo(3), services(5), nsswitch.conf(5)
607 */
608 static char *host_and_port(const struct sockaddr_storage *ss)
609 {
610 const struct sockaddr *sa = normalize_ip_address(ss);
611 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
612 static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
613 int ret;
614
615 ret = getnameinfo(sa, salen(sa),
616 hbuf, sizeof(hbuf),
617 sbuf, sizeof(sbuf),
618 NI_NUMERICHOST | NI_NUMERICSERV);
619 if (ret) {
620 snprintf(output, sizeof(output), "(unknown)");
621 PARA_WARNING_LOG("hostname lookup error (%s).\n",
622 gai_strerror(ret));
623 } else if (sa->sa_family == AF_INET6) {
624 snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
625 } else {
626 snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
627 }
628 return output;
629 }
630
631 /**
632 * Look up the local or remote side of a connected socket structure.
633 *
634 * \param fd The socket descriptor of the connected socket.
635 * \param getname Either \p getsockname() for local, or \p getpeername() for
636 * remote side.
637 *
638 * \return A static character string identifying hostname and port of the
639 * chosen side.
640 *
641 * \sa getsockname(2), getpeername(2).
642 */
643 static char *__get_sock_name(int fd, int (*getname)(int, struct sockaddr*,
644 socklen_t *))
645 {
646 struct sockaddr_storage ss;
647 socklen_t sslen = sizeof(ss);
648
649 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
650 static char *dont_know = "(don't know)";
651 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
652 fd, strerror(errno));
653 return dont_know;
654 }
655 return host_and_port(&ss);
656 }
657
658 /**
659 * Look up the local side of a connected socket structure.
660 *
661 * \param sockfd The file descriptor of the socket.
662 *
663 * \return A pointer to a static buffer containing hostname an port. This
664 * buffer must not be freed by the caller.
665 *
666 * \sa remote_name().
667 */
668 char *local_name(int sockfd)
669 {
670 return __get_sock_name(sockfd, getsockname);
671 }
672
673 /**
674 * Look up the remote side of a connected socket structure.
675 *
676 * \param sockfd The file descriptor of the socket.
677 *
678 * \return Analogous to the return value of \ref local_name() but for the
679 * remote side.
680 *
681 * \sa local_name().
682 */
683 char *remote_name(int sockfd)
684 {
685 return __get_sock_name(sockfd, getpeername);
686 }
687
688 /**
689 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
690 * \param ss Container of IPv4/6 address
691 * \return Extracted IPv4 address (different from 0) or 0 if unsuccessful.
692 *
693 * \sa RFC 3493
694 */
695 struct in_addr extract_v4_addr(const struct sockaddr_storage *ss)
696 {
697 struct in_addr ia = {.s_addr = 0};
698 const struct sockaddr *sa = normalize_ip_address(ss);
699
700 if (sa->sa_family == AF_INET)
701 ia = ((struct sockaddr_in *)sa)->sin_addr;
702 return ia;
703 }
704
705 /**
706 * Send a binary buffer.
707 *
708 * \param fd The file descriptor.
709 * \param buf The buffer to be sent.
710 * \param len The length of \a buf.
711 *
712 * Send out the buffer and try to resend the remaining part in case of short
713 * writes.
714 *
715 * \return Standard.
716 */
717 int send_bin_buffer(int fd, const char *buf, size_t len)
718 {
719 if (!len)
720 PARA_CRIT_LOG("len == 0\n");
721 return write_all(fd, buf, &len);
722 }
723
724 /**
725 * Send a \p NULL-terminated buffer.
726 *
727 * \param fd The file descriptor.
728 * \param buf The null-terminated buffer to be send.
729 *
730 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
731 *
732 * \return Standard.
733 */
734 int send_buffer(int fd, const char *buf)
735 {
736 return send_bin_buffer(fd, buf, strlen(buf));
737 }
738
739 /**
740 * Send a buffer given by a format string.
741 *
742 * \param fd The file descriptor.
743 * \param fmt A format string.
744 *
745 * \return Standard.
746 */
747 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
748 {
749 char *msg;
750 int ret;
751
752 PARA_VSPRINTF(fmt, msg);
753 ret = send_buffer(fd, msg);
754 free(msg);
755 return ret;
756 }
757
758 /**
759 * Receive data from a file descriptor.
760 *
761 * \param fd The file descriptor.
762 * \param buf The buffer to write the data to.
763 * \param size The size of \a buf.
764 *
765 * Receive at most \a size bytes from file descriptor \a fd.
766 *
767 * \return The number of bytes received on success, negative on errors, zero if
768 * the peer has performed an orderly shutdown.
769 *
770 * \sa recv(2).
771 */
772 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
773 {
774 ssize_t n;
775
776 n = recv(fd, buf, size, 0);
777 if (n == -1)
778 return -ERRNO_TO_PARA_ERROR(errno);
779 return n;
780 }
781
782 /**
783 * Receive and write terminating NULL byte.
784 *
785 * \param fd The file descriptor.
786 * \param buf The buffer to write the data to.
787 * \param size The size of \a buf.
788 *
789 * Read at most \a size - 1 bytes from file descriptor \a fd and
790 * write a NULL byte at the end of the received data.
791 *
792 * \return The return value of the underlying call to \a recv_bin_buffer().
793 *
794 * \sa recv_bin_buffer()
795 */
796 int recv_buffer(int fd, char *buf, size_t size)
797 {
798 int n;
799
800 assert(size);
801 n = recv_bin_buffer(fd, buf, size - 1);
802 if (n >= 0)
803 buf[n] = '\0';
804 else
805 *buf = '\0';
806 return n;
807 }
808
809 /**
810 * Wrapper around the accept system call.
811 *
812 * \param fd The listening socket.
813 * \param rfds An optional fd_set pointer.
814 * \param addr Structure which is filled in with the address of the peer socket.
815 * \param size Should contain the size of the structure pointed to by \a addr.
816 * \param new_fd Result pointer.
817 *
818 * Accept incoming connections on \a addr, retry if interrupted. If \a rfds is
819 * not \p NULL, return 0 if \a fd is not set in \a rfds without calling accept().
820 *
821 * \return Negative on errors, zero if no connections are present to be accepted,
822 * one otherwise.
823 *
824 * \sa accept(2).
825 */
826 int para_accept(int fd, fd_set *rfds, void *addr, socklen_t size, int *new_fd)
827 {
828 int ret;
829
830 if (rfds && !FD_ISSET(fd, rfds))
831 return 0;
832 do
833 ret = accept(fd, (struct sockaddr *) addr, &size);
834 while (ret < 0 && errno == EINTR);
835
836 if (ret >= 0) {
837 *new_fd = ret;
838 return 1;
839 }
840 if (errno == EAGAIN || errno == EWOULDBLOCK)
841 return 0;
842 return -ERRNO_TO_PARA_ERROR(errno);
843 }
844
845 /**
846 * Probe the list of DCCP CCIDs configured on this host.
847 * \param ccid_array Pointer to return statically allocated array in.
848 * \return Number of elements returned in \a ccid_array or error.
849 *
850 * NB: This feature is only available on Linux > 2.6.30; on older kernels
851 * ENOPROTOOPT ("Protocol not available") will be returned.
852 */
853 int dccp_available_ccids(uint8_t **ccid_array)
854 {
855 static uint8_t ccids[DCCP_MAX_HOST_CCIDS];
856 socklen_t nccids = sizeof(ccids);
857 int ret, fd;
858
859 ret = fd = makesock(IPPROTO_DCCP, 1, NULL, 0, NULL);
860 if (ret < 0)
861 return ret;
862
863 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
864 ccids, &nccids) < 0) {
865 ret = errno;
866 close(fd);
867 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
868 strerror(ret));
869 return -ERRNO_TO_PARA_ERROR(ret);
870 }
871
872 close(fd);
873 *ccid_array = ccids;
874 return nccids;
875 }
876
877 /**
878 * Prepare a structure for \p AF_UNIX socket addresses.
879 *
880 * \param u Pointer to the struct to be prepared.
881 * \param name The socket pathname.
882 *
883 * This just copies \a name to the sun_path component of \a u.
884 *
885 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
886 * than \p UNIX_PATH_MAX.
887 */
888 static int init_unix_addr(struct sockaddr_un *u, const char *name)
889 {
890 if (strlen(name) >= UNIX_PATH_MAX)
891 return -E_NAME_TOO_LONG;
892 memset(u->sun_path, 0, UNIX_PATH_MAX);
893 u->sun_family = PF_UNIX;
894 strcpy(u->sun_path, name);
895 return 1;
896 }
897
898 /**
899 * Prepare, create, and bind a socket for local communication.
900 *
901 * \param name The socket pathname.
902 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
903 * \param mode The desired mode of the socket.
904 *
905 * This function creates a local socket for sequenced, reliable,
906 * two-way, connection-based byte streams.
907 *
908 * \return The file descriptor, on success, negative on errors.
909 *
910 * \sa socket(2)
911 * \sa bind(2)
912 * \sa chmod(2)
913 */
914 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
915 mode_t mode)
916 {
917 int fd, ret;
918
919 ret = init_unix_addr(unix_addr, name);
920 if (ret < 0)
921 return ret;
922 ret = socket(PF_UNIX, SOCK_STREAM, 0);
923 if (ret < 0)
924 return -ERRNO_TO_PARA_ERROR(errno);
925 fd = ret;
926 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
927 if (ret < 0) {
928 ret = -ERRNO_TO_PARA_ERROR(errno);
929 goto err;
930 }
931 ret = -E_CHMOD;
932 if (chmod(name, mode) < 0)
933 goto err;
934 return fd;
935 err:
936 close(fd);
937 return ret;
938 }
939
940 /**
941 * Prepare, create, and connect to a Unix domain socket for local communication.
942 *
943 * \param name The socket pathname.
944 *
945 * This function creates a local socket for sequenced, reliable, two-way,
946 * connection-based byte streams.
947 *
948 * \return The file descriptor of the connected socket on success, negative on
949 * errors.
950 *
951 * \sa create_local_socket(), unix(7), connect(2).
952 */
953 int connect_local_socket(const char *name)
954 {
955 struct sockaddr_un unix_addr;
956 int fd, ret;
957
958 PARA_DEBUG_LOG("connecting to %s\n", name);
959 ret = init_unix_addr(&unix_addr, name);
960 if (ret < 0)
961 return ret;
962 fd = socket(PF_UNIX, SOCK_STREAM, 0);
963 if (fd < 0)
964 return -ERRNO_TO_PARA_ERROR(errno);
965 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) == -1) {
966 ret = -ERRNO_TO_PARA_ERROR(errno);
967 goto err;
968 }
969 return fd;
970 err:
971 close(fd);
972 return ret;
973 }
974
975 #ifndef HAVE_UCRED
976 ssize_t send_cred_buffer(int sock, char *buf)
977 {
978 return send_buffer(sock, buf);
979 }
980 int recv_cred_buffer(int fd, char *buf, size_t size)
981 {
982 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
983 }
984 #else /* HAVE_UCRED */
985 /**
986 * Send \p NULL-terminated buffer and Unix credentials of the current process.
987 *
988 * \param sock The socket file descriptor.
989 * \param buf The buffer to be sent.
990 *
991 * \return On success, this call returns the number of characters sent. On
992 * error, \p -E_SENDMSG is returned.
993 *
994 * \sa sendmsg(2), okir's Black Hats Manual.
995 */
996 ssize_t send_cred_buffer(int sock, char *buf)
997 {
998 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
999 struct msghdr msg;
1000 struct cmsghdr *cmsg;
1001 static struct iovec iov;
1002 struct ucred c;
1003 int ret;
1004
1005 /* Response data */
1006 iov.iov_base = buf;
1007 iov.iov_len = strlen(buf);
1008 c.pid = getpid();
1009 c.uid = getuid();
1010 c.gid = getgid();
1011 /* compose the message */
1012 memset(&msg, 0, sizeof(msg));
1013 msg.msg_iov = &iov;
1014 msg.msg_iovlen = 1;
1015 msg.msg_control = control;
1016 msg.msg_controllen = sizeof(control);
1017 /* attach the ucred struct */
1018 cmsg = CMSG_FIRSTHDR(&msg);
1019 cmsg->cmsg_level = SOL_SOCKET;
1020 cmsg->cmsg_type = SCM_CREDENTIALS;
1021 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
1022 *(struct ucred *)CMSG_DATA(cmsg) = c;
1023 msg.msg_controllen = cmsg->cmsg_len;
1024 ret = sendmsg(sock, &msg, 0);
1025 if (ret < 0)
1026 ret = -E_SENDMSG;
1027 return ret;
1028 }
1029
1030 static void dispose_fds(int *fds, unsigned num)
1031 {
1032 int i;
1033
1034 for (i = 0; i < num; i++)
1035 close(fds[i]);
1036 }
1037
1038 /**
1039 * Receive a buffer and the Unix credentials of the sending process.
1040 *
1041 * \param fd the socket file descriptor.
1042 * \param buf the buffer to store the message.
1043 * \param size the size of \a buffer.
1044 *
1045 * \return negative on errors, the user id on success.
1046 *
1047 * \sa recvmsg(2), okir's Black Hats Manual.
1048 */
1049 int recv_cred_buffer(int fd, char *buf, size_t size)
1050 {
1051 char control[255];
1052 struct msghdr msg;
1053 struct cmsghdr *cmsg;
1054 struct iovec iov;
1055 int result = 0;
1056 int yes = 1;
1057 struct ucred cred;
1058
1059 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
1060 memset(&msg, 0, sizeof(msg));
1061 memset(buf, 0, size);
1062 iov.iov_base = buf;
1063 iov.iov_len = size;
1064 msg.msg_iov = &iov;
1065 msg.msg_iovlen = 1;
1066 msg.msg_control = control;
1067 msg.msg_controllen = sizeof(control);
1068 if (recvmsg(fd, &msg, 0) < 0)
1069 return -E_RECVMSG;
1070 result = -E_SCM_CREDENTIALS;
1071 cmsg = CMSG_FIRSTHDR(&msg);
1072 while (cmsg) {
1073 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
1074 == SCM_CREDENTIALS) {
1075 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
1076 result = cred.uid;
1077 } else
1078 if (cmsg->cmsg_level == SOL_SOCKET
1079 && cmsg->cmsg_type == SCM_RIGHTS) {
1080 dispose_fds((int *) CMSG_DATA(cmsg),
1081 (cmsg->cmsg_len - CMSG_LEN(0))
1082 / sizeof(int));
1083 }
1084 cmsg = CMSG_NXTHDR(&msg, cmsg);
1085 }
1086 return result;
1087 }
1088 #endif /* HAVE_UCRED */