fecdec.c: Add some more sanity checks to find_group().
[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
31 #include "para.h"
32 #include "error.h"
33 #include "net.h"
34 #include "string.h"
35 #include "fd.h"
36
37
38 /** Information about one encrypted connection. */
39 struct crypt_data {
40 /** Function used to decrypt received data. */
41 crypt_function *recv;
42 /** Function used to encrypt data to be sent. */
43 crypt_function *send;
44 /**
45 * Context-dependent data (crypt keys), passed verbatim to the above
46 * crypt functions.
47 */
48 void *private_data;
49 };
50 /** Array holding per fd crypt data. */
51 static struct crypt_data *crypt_data_array;
52 /** Current size of the crypt data array. */
53 static unsigned cda_size = 0;
54
55 /**
56 * Activate encryption for one file descriptor.
57 *
58 * \param fd The file descriptor.
59 * \param recv_f The function used for decrypting received data.
60 * \param send_f The function used for encrypting before sending.
61 * \param private_data User data supplied by the caller.
62 */
63 void enable_crypt(int fd, crypt_function *recv_f, crypt_function *send_f,
64 void *private_data)
65 {
66 if (fd + 1 > cda_size) {
67 crypt_data_array = para_realloc(crypt_data_array,
68 (fd + 1) * sizeof(struct crypt_data));
69 memset(crypt_data_array + cda_size, 0,
70 (fd + 1 - cda_size) * sizeof(struct crypt_data));
71 cda_size = fd + 1;
72 }
73 crypt_data_array[fd].recv = recv_f;
74 crypt_data_array[fd].send = send_f;
75 crypt_data_array[fd].private_data = private_data;
76 PARA_INFO_LOG("rc4 encryption activated for fd %d\n", fd);
77 }
78
79 /**
80 * Deactivate encryption for a given fd.
81 *
82 * \param fd The file descriptor.
83 *
84 * This must be called if and only if \p fd was activated via enable_crypt().
85 */
86 void disable_crypt(int fd)
87 {
88 if (cda_size < fd + 1)
89 return;
90 crypt_data_array[fd].recv = NULL;
91 crypt_data_array[fd].send = NULL;
92 crypt_data_array[fd].private_data = NULL;
93 }
94
95 /**
96 * Match string as a candidate IPv4 address.
97 *
98 * \param address The string to match.
99 * \return True if \a address has "dot-quad" format.
100 */
101 static bool is_v4_dot_quad(const char *address)
102 {
103 bool result;
104 regex_t r;
105
106 assert(!regcomp(&r, "^([0-9]+\\.){3}[0-9]+$", REG_EXTENDED|REG_NOSUB));
107 result = regexec(&r, address, 0, NULL, 0) == 0;
108 regfree(&r);
109 return result;
110 }
111
112 /**
113 * Perform basic syntax checking on the host-part of an URL:
114 *
115 * - Since ':' is invalid in IPv4 addresses and DNS names, the
116 * presence of ':' causes interpretation as IPv6 address;
117 * - next the first-match-wins algorithm from RFC 3986 is applied;
118 * - else the string is considered as DNS name, to be resolved later.
119 *
120 * \param host The host string to check.
121 * \return True if \a host passes the syntax checks.
122 *
123 * \sa RFC 3986, 3.2.2; RFC 1123, 2.1; RFC 1034, 3.5
124 */
125 static bool host_string_ok(const char *host)
126 {
127 if (host == NULL || *host == '\0')
128 return false;
129 if (strchr(host, ':') != NULL)
130 return is_valid_ipv6_address(host);
131 if (is_v4_dot_quad(host))
132 return is_valid_ipv4_address(host);
133 return true;
134 }
135
136 /**
137 * Parse and validate URL string.
138 *
139 * The URL syntax is loosely based on RFC 3986, supporting one of
140 * - "["host"]"[:port] for native IPv6 addresses and
141 * - host[:port] for IPv4 hostnames and DNS names.
142 *
143 * Native IPv6 addresses must be enclosed in square brackets, since
144 * otherwise there is an ambiguity with the port separator `:'.
145 * The 'port' part is always considered to be a number; if absent,
146 * it is set to -1, to indicate that a default port is to be used.
147 *
148 * The following are valid examples:
149 * - 10.10.1.1
150 * - 10.10.1.2:8000
151 * - localhost
152 * - localhost:8001
153 * - [::1]:8000
154 * - [badc0de::1]
155 *
156 * \param url The URL string to take apart.
157 * \param host To return the copied host part of \a url.
158 * \param hostlen The maximum length of \a host.
159 * \param port To return the port number (if any) of \a url.
160 *
161 * \return Pointer to \a host, or NULL if failed.
162 * If NULL is returned, \a host and \a portnum are undefined. If no
163 * port number was present in \a url, \a portnum is set to -1.
164 *
165 * \sa RFC 3986, 3.2.2/3.2.3
166 */
167 char *parse_url(const char *url,
168 char *host, ssize_t hostlen,
169 int32_t *port)
170 {
171 const char *o = url;
172 char *c = host, *end = c + (hostlen - 1);
173
174 *port = -1;
175
176 if (o == NULL || hostlen < 1)
177 goto failed;
178
179 if (*o == '[') {
180 for (++o; (*c = *o == ']' ? '\0' : *o); c++, o++)
181 if (c == end)
182 goto failed;
183
184 if (*o++ != ']' || (*o != '\0' && *o != ':'))
185 goto failed;
186 } else {
187 for (; (*c = *o == ':'? '\0' : *o); c++, o++)
188 if (c == end)
189 goto failed;
190 }
191
192 if (*o == ':')
193 if (para_atoi32(++o, port) < 0 ||
194 *port < 0 || *port > 0xffff)
195 goto failed;
196
197 if (host_string_ok(host))
198 return host;
199 failed:
200 *host = '\0';
201 return NULL;
202 }
203
204 /**
205 * Determine the socket type for a given layer-4 protocol.
206 *
207 * \param l4type The symbolic name of the transport-layer protocol.
208 *
209 * \sa ip(7), socket(2)
210 */
211 static inline int sock_type(const unsigned l4type)
212 {
213 switch (l4type) {
214 case IPPROTO_UDP: return SOCK_DGRAM;
215 case IPPROTO_TCP: return SOCK_STREAM;
216 case IPPROTO_DCCP: return SOCK_DCCP;
217 }
218 return -1; /* not supported here */
219 }
220
221 /**
222 * Pretty-print transport-layer name.
223 */
224 static const char *layer4_name(const unsigned l4type)
225 {
226 switch (l4type) {
227 case IPPROTO_UDP: return "UDP";
228 case IPPROTO_TCP: return "TCP";
229 case IPPROTO_DCCP: return "DCCP";
230 }
231 return "UNKNOWN PROTOCOL";
232 }
233
234 /**
235 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
236 *
237 * \param l3type The layer-3 type (\p AF_INET, \p AF_INET6, \p AF_UNSPEC).
238 * \param l4type The layer-4 type (\p IPPROTO_xxx).
239 * \param passive Whether this is a passive (1) or active (0) socket.
240 * \param host Remote or local hostname or IPv/6 address string.
241 * \param port_number Decimal port number.
242 *
243 * This creates a ready-made IPv4/v6 socket structure after looking up the
244 * necessary parameters. The interpretation of \a host depends on the value of
245 * \a passive:
246 * - on a passive socket host is interpreted as an interface IPv4/6 address
247 * (can be left NULL);
248 * - on an active socket, \a host is the peer DNS name or IPv4/6 address
249 * to connect to;
250 * - \a port_number is in either case the numeric port number (not service
251 * string).
252 *
253 * Furthermore, bind(2) is called on passive sockets, and connect(2) on active
254 * sockets. The algorithm tries all possible address combinations until it
255 * succeeds.
256 *
257 * \return This function returns 1 on success and \a -E_ADDRESS_LOOKUP when no
258 * matching connection could be set up (with details in the error log).
259 *
260 * \sa ipv6(7), getaddrinfo(3), bind(2), connect(2).
261 */
262 int makesock(unsigned l3type, unsigned l4type, int passive,
263 const char *host, unsigned short port_number)
264 {
265 struct addrinfo *local = NULL, *src,
266 *remote = NULL, *dst, hints;
267 int rc, on = 1, sockfd = -1,
268 socktype = sock_type(l4type);
269 char port[6]; /* port number has at most 5 digits */
270
271 sprintf(port, "%u", port_number);
272 /* Set up address hint structure */
273 memset(&hints, 0, sizeof(hints));
274 hints.ai_family = l3type;
275 hints.ai_socktype = socktype;
276 /*
277 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
278 * (and only then) pretend to be UDP.
279 */
280 if (l4type == IPPROTO_DCCP)
281 hints.ai_socktype = SOCK_DGRAM;
282
283 /* only use addresses available on the host */
284 hints.ai_flags = AI_ADDRCONFIG;
285 if (l3type == AF_INET6)
286 /* use v4-mapped-v6 if no v6 addresses found */
287 hints.ai_flags |= AI_V4MAPPED | AI_ALL;
288
289 if (passive && host == NULL)
290 hints.ai_flags |= AI_PASSIVE;
291
292 /* Obtain local/remote address information */
293 if ((rc = getaddrinfo(host, port, &hints, passive ? &local : &remote))) {
294 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s.\n",
295 layer4_name(l4type),
296 host? host : (passive? "[loopback]" : "[localhost]"),
297 port, gai_strerror(rc));
298 return -E_ADDRESS_LOOKUP;
299 }
300
301 /* Iterate over all src/dst combination, exhausting dst first */
302 for (src = local, dst = remote; src != NULL || dst != NULL; /* no op */ ) {
303 if (src && dst && src->ai_family == AF_INET
304 && dst->ai_family == AF_INET6)
305 goto get_next_dst; /* v4 -> v6 is not possible */
306
307 sockfd = socket(src ? src->ai_family : dst->ai_family,
308 socktype, l4type);
309 if (sockfd < 0)
310 goto get_next_dst;
311
312 /*
313 * Set those options that need to be set before establishing
314 * the connection. Reuse the address on passive (listening)
315 * sockets to avoid failure on restart.
316 */
317 if (passive && setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
318 &on, sizeof(on)) == -1) {
319 PARA_ERROR_LOG("can not set SO_REUSEADDR: %s\n",
320 strerror(errno));
321 return -ERRNO_TO_PARA_ERROR(errno);
322 }
323
324 if (src) {
325 if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
326 close(sockfd);
327 goto get_next_src;
328 }
329 if (!dst) /* bind-only completed successfully */
330 break;
331 }
332
333 if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
334 break; /* connection completed successfully */
335 close(sockfd);
336 get_next_dst:
337 if (dst && (dst = dst->ai_next))
338 continue;
339 get_next_src:
340 if (src && (src = src->ai_next)) /* restart inner loop */
341 dst = remote;
342 }
343 if (local)
344 freeaddrinfo(local);
345 if (remote)
346 freeaddrinfo(remote);
347
348 if (src == NULL && dst == NULL) {
349 PARA_ERROR_LOG("can not create %s socket %s#%s.\n",
350 layer4_name(l4type), host? host : (passive?
351 "[loopback]" : "[localhost]"), port);
352 return -ERRNO_TO_PARA_ERROR(errno);
353 }
354 return sockfd;
355 }
356
357 /**
358 * Create a passive / listening socket.
359 *
360 * \param l3type The network-layer type (\p AF_xxx).
361 * \param l4type The transport-layer type (\p IPPROTO_xxx).
362 * \param port The decimal port number to listen on.
363 *
364 * \return Positive integer (socket descriptor) on success, negative value
365 * otherwise.
366 *
367 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
368 */
369 int para_listen(unsigned l3type, unsigned l4type, unsigned short port)
370 {
371 int ret, fd = makesock(l3type, l4type, 1, NULL, port);
372
373 if (fd > 0) {
374 ret = listen(fd, BACKLOG);
375 if (ret < 0) {
376 close(fd);
377 return -ERRNO_TO_PARA_ERROR(errno);
378 }
379 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
380 layer4_name(l4type), port, fd);
381 }
382 return fd;
383 }
384
385 /**
386 * Print numeric host and port number (beware - uses static char).
387 *
388 * \param sa The IPv4/IPv6 socket address to use.
389 * \param len The length of \p sa.
390 *
391 * \sa getnameinfo(3).
392 */
393 static char *host_and_port(struct sockaddr *sa, socklen_t len)
394 {
395 static char output[NI_MAXHOST + NI_MAXSERV + 2];
396 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
397 int ret;
398
399 ret = getnameinfo(sa, len, hbuf, sizeof(hbuf), sbuf, sizeof(sbuf),
400 NI_NUMERICHOST | NI_NUMERICSERV);
401 if (ret) {
402 PARA_WARNING_LOG("hostname lookup error (%s).\n",
403 gai_strerror(ret));
404 sprintf(output, "(unknown)");
405 } else
406 sprintf(output, "%s#%s", hbuf, sbuf);
407 return output;
408 }
409
410 /**
411 * Look up the local or remote side of a connected socket structure.
412 *
413 * \param fd The socket descriptor of the connected socket.
414 * \param getname Either \p getsockname() for local, or \p getpeername() for
415 * remote side.
416 *
417 * \return A static character string identifying hostname and port of the
418 * chosen side.
419 *
420 * \sa getsockname(2), getpeername(2).
421 */
422 static char *__get_sock_name(int fd, int (*getname)(int, struct sockaddr*,
423 socklen_t *))
424 {
425 struct sockaddr_storage ss;
426 socklen_t sslen = sizeof(ss);
427
428 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
429 static char *dont_know = "(don't know)";
430 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
431 fd, strerror(errno));
432 return dont_know;
433 }
434 return host_and_port((struct sockaddr *)&ss, sslen);
435 }
436
437 char *local_name(int sockfd)
438 {
439 return __get_sock_name(sockfd, getsockname);
440 }
441
442 char *remote_name(int sockfd)
443 {
444 return __get_sock_name(sockfd, getpeername);
445 }
446
447 /**
448 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
449 * \param ss Container of IPv4/6 address
450 * \return Extracted IPv4 address (different from 0) or 0 if unsuccessful.
451 *
452 * \sa RFC 3493
453 */
454 struct in_addr extract_v4_addr(const struct sockaddr_storage *ss)
455 {
456 struct in_addr ia = {.s_addr = 0};
457
458 if (ss->ss_family == AF_INET)
459 ia.s_addr = ((struct sockaddr_in *)ss)->sin_addr.s_addr;
460 if (ss->ss_family == AF_INET6) {
461 const struct in6_addr v6_addr = ((struct sockaddr_in6 *)ss)->sin6_addr;
462
463 if (IN6_IS_ADDR_V4MAPPED(&v6_addr))
464 memcpy(&ia.s_addr, &(v6_addr.s6_addr[12]), 4);
465 }
466 return ia;
467 }
468
469 /**
470 * Encrypt and send a binary buffer.
471 *
472 * \param fd The file descriptor.
473 * \param buf The buffer to be encrypted and sent.
474 * \param len The length of \a buf.
475 *
476 * Check if encryption is available. If yes, encrypt the given buffer. Send
477 * out the buffer, encrypted or not, and try to resend the remaing part in case
478 * of short writes.
479 *
480 * \return Standard.
481 */
482 int send_bin_buffer(int fd, const char *buf, size_t len)
483 {
484 int ret;
485 crypt_function *cf = NULL;
486
487 if (!len)
488 PARA_CRIT_LOG("len == 0\n");
489 if (fd + 1 <= cda_size)
490 cf = crypt_data_array[fd].send;
491 if (cf) {
492 void *private = crypt_data_array[fd].private_data;
493 /* RC4 may write more than len to the output buffer */
494 unsigned char *outbuf = para_malloc(ROUND_UP(len, 8));
495 (*cf)(len, (unsigned char *)buf, outbuf, private);
496 ret = write_all(fd, (char *)outbuf, &len);
497 free(outbuf);
498 } else
499 ret = write_all(fd, buf, &len);
500 return ret;
501 }
502
503 /**
504 * Encrypt and send null terminated buffer.
505 *
506 * \param fd The file descriptor.
507 * \param buf The null-terminated buffer to be send.
508 *
509 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
510 *
511 * \return Standard.
512 */
513 int send_buffer(int fd, const char *buf)
514 {
515 return send_bin_buffer(fd, buf, strlen(buf));
516 }
517
518
519 /**
520 * Send and encrypt a buffer given by a format string.
521 *
522 * \param fd The file descriptor.
523 * \param fmt A format string.
524 *
525 * \return Standard.
526 */
527 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
528 {
529 char *msg;
530 int ret;
531
532 PARA_VSPRINTF(fmt, msg);
533 ret = send_buffer(fd, msg);
534 free(msg);
535 return ret;
536 }
537
538 /**
539 * Receive and decrypt.
540 *
541 * \param fd The file descriptor.
542 * \param buf The buffer to write the decrypted data to.
543 * \param size The size of \a buf.
544 *
545 * Receive at most \a size bytes from file descriptor \a fd. If encryption is
546 * available, decrypt the received buffer.
547 *
548 * \return The number of bytes received on success, negative on errors.
549 *
550 * \sa recv(2)
551 */
552 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
553 {
554 ssize_t n;
555 crypt_function *cf = NULL;
556
557 if (fd + 1 <= cda_size)
558 cf = crypt_data_array[fd].recv;
559 if (cf) {
560 unsigned char *tmp = para_malloc(size);
561 void *private = crypt_data_array[fd].private_data;
562 n = recv(fd, tmp, size, 0);
563 if (n > 0) {
564 size_t numbytes = n;
565 unsigned char *b = (unsigned char *)buf;
566 (*cf)(numbytes, tmp, b, private);
567 }
568 free(tmp);
569 } else
570 n = recv(fd, buf, size, 0);
571 if (n == -1)
572 return -ERRNO_TO_PARA_ERROR(errno);
573 return n;
574 }
575
576 /**
577 * Receive, decrypt and write terminating NULL byte.
578 *
579 * \param fd The file descriptor.
580 * \param buf The buffer to write the decrypted data to.
581 * \param size The size of \a buf.
582 *
583 * Read and decrypt at most \a size - 1 bytes from file descriptor \a fd and
584 * write a NULL byte at the end of the received data.
585 *
586 * \return The return value of the underlying call to \a recv_bin_buffer().
587 *
588 * \sa recv_bin_buffer()
589 */
590 int recv_buffer(int fd, char *buf, size_t size)
591 {
592 int n;
593
594 assert(size);
595 n = recv_bin_buffer(fd, buf, size - 1);
596 if (n >= 0)
597 buf[n] = '\0';
598 else
599 *buf = '\0';
600 return n;
601 }
602
603 /**
604 * Wrapper around the accept system call.
605 *
606 * \param fd The listening socket.
607 * \param addr Structure which is filled in with the address of the peer socket.
608 * \param size Should contain the size of the structure pointed to by \a addr.
609 *
610 * Accept incoming connections on \a addr. Retry if interrupted.
611 *
612 * \return The new file descriptor on success, negative on errors.
613 *
614 * \sa accept(2).
615 */
616 int para_accept(int fd, void *addr, socklen_t size)
617 {
618 int new_fd;
619
620 do
621 new_fd = accept(fd, (struct sockaddr *) addr, &size);
622 while (new_fd < 0 && errno == EINTR);
623 return new_fd < 0? -ERRNO_TO_PARA_ERROR(errno) : new_fd;
624 }
625
626 /**
627 * Prepare a structure for \p AF_UNIX socket addresses.
628 *
629 * \param u Pointer to the struct to be prepared.
630 * \param name The socket pathname.
631 *
632 * This just copies \a name to the sun_path component of \a u.
633 *
634 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
635 * than \p UNIX_PATH_MAX.
636 */
637 static int init_unix_addr(struct sockaddr_un *u, const char *name)
638 {
639 if (strlen(name) >= UNIX_PATH_MAX)
640 return -E_NAME_TOO_LONG;
641 memset(u->sun_path, 0, UNIX_PATH_MAX);
642 u->sun_family = PF_UNIX;
643 strcpy(u->sun_path, name);
644 return 1;
645 }
646
647 /**
648 * Prepare, create, and bind a socket for local communication.
649 *
650 * \param name The socket pathname.
651 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
652 * \param mode The desired mode of the socket.
653 *
654 * This function creates a local socket for sequenced, reliable,
655 * two-way, connection-based byte streams.
656 *
657 * \return The file descriptor, on success, negative on errors.
658 *
659 * \sa socket(2)
660 * \sa bind(2)
661 * \sa chmod(2)
662 */
663 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
664 mode_t mode)
665 {
666 int fd, ret;
667
668 ret = init_unix_addr(unix_addr, name);
669 if (ret < 0)
670 return ret;
671 ret = socket(PF_UNIX, SOCK_STREAM, 0);
672 if (ret < 0)
673 return -ERRNO_TO_PARA_ERROR(errno);
674 fd = ret;
675 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
676 if (ret < 0) {
677 ret = -ERRNO_TO_PARA_ERROR(errno);
678 goto err;
679 }
680 ret = -E_CHMOD;
681 if (chmod(name, mode) < 0)
682 goto err;
683 return fd;
684 err:
685 close(fd);
686 return ret;
687 }
688
689 /**
690 * Prepare, create, and connect to a Unix domain socket for local communication.
691 *
692 * \param name The socket pathname.
693 *
694 * This function creates a local socket for sequenced, reliable, two-way,
695 * connection-based byte streams.
696 *
697 * \return The file descriptor, on success, negative on errors.
698 *
699 * \sa create_local_socket(), unix(7), connect(2).
700 */
701 int create_remote_socket(const char *name)
702 {
703 struct sockaddr_un unix_addr;
704 int fd, ret;
705
706 ret = init_unix_addr(&unix_addr, name);
707 if (ret < 0)
708 return ret;
709 fd = socket(PF_UNIX, SOCK_STREAM, 0);
710 if (fd < 0)
711 return -ERRNO_TO_PARA_ERROR(errno);
712 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) == -1) {
713 ret = -ERRNO_TO_PARA_ERROR(errno);
714 goto err;
715 }
716 return fd;
717 err:
718 close(fd);
719 return ret;
720 }
721
722 #ifndef HAVE_UCRED
723 ssize_t send_cred_buffer(int sock, char *buf)
724 {
725 return send_buffer(sock, buf);
726 }
727 int recv_cred_buffer(int fd, char *buf, size_t size)
728 {
729 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
730 }
731 #else /* HAVE_UCRED */
732 /**
733 * Send \p NULL-terminated buffer and Unix credentials of the current process.
734 *
735 * \param sock The socket file descriptor.
736 * \param buf The buffer to be sent.
737 *
738 * \return On success, this call returns the number of characters sent. On
739 * error, \p -E_SENDMSG is returned.
740 *
741 * \sa sendmsg(2), okir's Black Hats Manual.
742 */
743 ssize_t send_cred_buffer(int sock, char *buf)
744 {
745 char control[sizeof(struct cmsghdr) + 10];
746 struct msghdr msg;
747 struct cmsghdr *cmsg;
748 static struct iovec iov;
749 struct ucred c;
750 int ret;
751
752 /* Response data */
753 iov.iov_base = buf;
754 iov.iov_len = strlen(buf);
755 c.pid = getpid();
756 c.uid = getuid();
757 c.gid = getgid();
758 /* compose the message */
759 memset(&msg, 0, sizeof(msg));
760 msg.msg_iov = &iov;
761 msg.msg_iovlen = 1;
762 msg.msg_control = control;
763 msg.msg_controllen = sizeof(control);
764 /* attach the ucred struct */
765 cmsg = CMSG_FIRSTHDR(&msg);
766 cmsg->cmsg_level = SOL_SOCKET;
767 cmsg->cmsg_type = SCM_CREDENTIALS;
768 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
769 *(struct ucred *)CMSG_DATA(cmsg) = c;
770 msg.msg_controllen = cmsg->cmsg_len;
771 ret = sendmsg(sock, &msg, 0);
772 if (ret < 0)
773 ret = -E_SENDMSG;
774 return ret;
775 }
776
777 static void dispose_fds(int *fds, unsigned num)
778 {
779 int i;
780
781 for (i = 0; i < num; i++)
782 close(fds[i]);
783 }
784
785 /**
786 * Receive a buffer and the Unix credentials of the sending process.
787 *
788 * \param fd the socket file descriptor.
789 * \param buf the buffer to store the message.
790 * \param size the size of \a buffer.
791 *
792 * \return negative on errors, the user id on success.
793 *
794 * \sa recvmsg(2), okir's Black Hats Manual.
795 */
796 int recv_cred_buffer(int fd, char *buf, size_t size)
797 {
798 char control[255];
799 struct msghdr msg;
800 struct cmsghdr *cmsg;
801 struct iovec iov;
802 int result = 0;
803 int yes = 1;
804 struct ucred cred;
805
806 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
807 memset(&msg, 0, sizeof(msg));
808 memset(buf, 0, size);
809 iov.iov_base = buf;
810 iov.iov_len = size;
811 msg.msg_iov = &iov;
812 msg.msg_iovlen = 1;
813 msg.msg_control = control;
814 msg.msg_controllen = sizeof(control);
815 if (recvmsg(fd, &msg, 0) < 0)
816 return -E_RECVMSG;
817 result = -E_SCM_CREDENTIALS;
818 cmsg = CMSG_FIRSTHDR(&msg);
819 while (cmsg) {
820 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
821 == SCM_CREDENTIALS) {
822 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
823 result = cred.uid;
824 } else
825 if (cmsg->cmsg_level == SOL_SOCKET
826 && cmsg->cmsg_type == SCM_RIGHTS) {
827 dispose_fds((int *) CMSG_DATA(cmsg),
828 (cmsg->cmsg_len - CMSG_LEN(0))
829 / sizeof(int));
830 }
831 cmsg = CMSG_NXTHDR(&msg, cmsg);
832 }
833 return result;
834 }
835 #endif /* HAVE_UCRED */
836
837 /**
838 * Receive a buffer and check for a pattern.
839 *
840 * \param fd The file descriptor to receive from.
841 * \param pattern The expected pattern.
842 * \param bufsize The size of the internal buffer.
843 *
844 * \return Positive if \a pattern was received, negative otherwise.
845 *
846 * This function tries to receive at most \a bufsize bytes from file descriptor
847 * \a fd. If at least \p strlen(\a pattern) bytes were received, the beginning
848 * of the received buffer is compared with \a pattern, ignoring case.
849 *
850 * \sa recv_buffer(), \sa strncasecmp(3).
851 */
852 int recv_pattern(int fd, const char *pattern, size_t bufsize)
853 {
854 size_t len = strlen(pattern);
855 char *buf = para_malloc(bufsize + 1);
856 int ret = -E_RECV_PATTERN, n = recv_buffer(fd, buf, bufsize + 1);
857
858 if (n < len)
859 goto out;
860 if (strncasecmp(buf, pattern, len))
861 goto out;
862 ret = 1;
863 out:
864 if (ret < 0) {
865 PARA_NOTICE_LOG("n = %d, did not receive pattern '%s'\n", n,
866 pattern);
867 if (n > 0)
868 PARA_NOTICE_LOG("recvd: %s\n", buf);
869 }
870 free(buf);
871 return ret;
872 }