02_Reverse-lookup-support.diff
[paraslash.git] / net.c
1 /*
2 * Copyright (C) 2005-2007 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 #include <netdb.h>
10
11 #include "para.h"
12 #include "error.h"
13 #include "net.h"
14 #include "string.h"
15
16
17 /** Information about one encrypted connection. */
18 struct crypt_data {
19 /** Function used to decrypt received data. */
20 crypt_function *recv;
21 /** Function used to encrypt data to be sent. */
22 crypt_function *send;
23 /**
24 * Context-dependent data (crypt keys), passed verbatim to the above
25 * crypt functions.
26 */
27 void *private_data;
28 };
29 /** Array holding per fd crypt data. */
30 static struct crypt_data *crypt_data_array;
31 /** Current size of the crypt data array. */
32 static unsigned cda_size = 0;
33
34 /**
35 * Activate encryption for one file descriptor.
36 *
37 * \param fd The file descriptor.
38 * \param recv_f The function used for decrypting received data.
39 * \param send_f The function used for encrypting before sending.
40 * \param private_data User data supplied by the caller.
41 */
42 void enable_crypt(int fd, crypt_function *recv_f, crypt_function *send_f,
43 void *private_data)
44 {
45 if (fd + 1 > cda_size) {
46 crypt_data_array = para_realloc(crypt_data_array,
47 (fd + 1) * sizeof(struct crypt_data));
48 memset(crypt_data_array + cda_size, 0,
49 (fd + 1 - cda_size) * sizeof(struct crypt_data));
50 cda_size = fd + 1;
51 }
52 crypt_data_array[fd].recv = recv_f;
53 crypt_data_array[fd].send = send_f;
54 crypt_data_array[fd].private_data = private_data;
55 PARA_INFO_LOG("rc4 encryption activated for fd %d\n", fd);
56 }
57
58 /**
59 * Deactivate encryption for a given fd.
60 *
61 * \param fd The file descriptor.
62 *
63 * This must be called if and only if \p fd was activated via enable_crypt().
64 */
65 void disable_crypt(int fd)
66 {
67 if (cda_size < fd + 1)
68 return;
69 crypt_data_array[fd].recv = NULL;
70 crypt_data_array[fd].send = NULL;
71 crypt_data_array[fd].private_data = NULL;
72 }
73
74
75 /**
76 * Initialize a struct sockaddr_in.
77 *
78 * \param addr A pointer to the struct to be initialized.
79 * \param port The port number to use.
80 * \param he The address to use.
81 *
82 * If \a he is null (server mode), \a addr->sin_addr is initialized with \p
83 * INADDR_ANY. Otherwise, the address given by \a he is copied to addr.
84 */
85 static void init_sockaddr(struct sockaddr_in *addr, int port, const struct hostent *he)
86 {
87 /* host byte order */
88 addr->sin_family = AF_INET;
89 /* short, network byte order */
90 addr->sin_port = htons(port);
91 if (he)
92 addr->sin_addr = *((struct in_addr *)he->h_addr);
93 else
94 addr->sin_addr.s_addr = INADDR_ANY;
95 /* zero the rest of the struct */
96 memset(&addr->sin_zero, '\0', 8);
97 }
98
99 /**
100 * Determine the socket type for a given layer-4 protocol.
101 *
102 * \param l4type The symbolic name of the transport-layer protocol.
103 *
104 * \sa ip(7), socket(2)
105 */
106 static inline int sock_type(const unsigned l4type)
107 {
108 switch (l4type) {
109 case IPPROTO_UDP: return SOCK_DGRAM;
110 case IPPROTO_TCP: return SOCK_STREAM;
111 case IPPROTO_DCCP: return SOCK_DCCP;
112 }
113 return -1; /* not supported here */
114 }
115
116 /**
117 * Pretty-print transport-layer name.
118 */
119 static const char *layer4_name(const unsigned l4type)
120 {
121 switch (l4type) {
122 case IPPROTO_UDP: return "UDP";
123 case IPPROTO_TCP: return "TCP";
124 case IPPROTO_DCCP: return "DCCP";
125 }
126 return "UNKNOWN PROTOCOL";
127 }
128
129 /**
130 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
131 *
132 * @param l3type The layer-3 type (\p AF_INET, \p AF_INET6, \p AF_UNSPEC)
133 * @param l4type The layer-4 type (\p IPPROTO_xxx).
134 * @param passive Whether this is a passive (1) or active (0) socket/
135 * @param host Remote or local hostname or IPv/6 address string.
136 * @param port_number Decimal port number.
137 *
138 * This creates a ready-made IPv4/v6 socket structure after looking up the necessary
139 * parameters. The interpretation of \a host depends on the value of \a passive:
140 * - on a passive socket host is interpreted as an interface IPv4/6 address
141 * (can be left NULL);
142 * - on an active socket, \a host is the peer DNS name or IPv4/6 address to connect to;
143 * - \a port_number is in either case the numeric port number (not service string).
144 * Furthermore, bind(2) is called on passive sockets, and connect(2) on active sockets.
145 * The algorithm tries all possible address combinations until it succeeds.
146 *
147 * \return This function returns 1 on success and \a -E_ADDRESS_LOOKUP when no matching
148 * connection could be set up (with details in the error log).
149 *
150 * \sa ipv6(7), getaddrinfo(3), bind(2), connect(2)
151 */
152 int makesock(unsigned l3type, unsigned l4type, int passive,
153 const char *host, unsigned short port_number)
154 {
155 struct addrinfo *local = NULL, *src,
156 *remote = NULL, *dst, hints;
157 char *port = make_message("%u", port_number);
158 int rc, on = 1, sockfd = -1,
159 socktype = sock_type(l4type);
160
161 /*
162 * Set up address hint structure
163 */
164 memset(&hints, 0, sizeof(hints));
165 hints.ai_family = l3type;
166 /* getaddrinfo does not really work well with SOCK_DCCP */
167 if (socktype == SOCK_DGRAM || socktype == SOCK_STREAM)
168 hints.ai_socktype = socktype;
169
170 /* only use addresses available on the host */
171 hints.ai_flags = AI_ADDRCONFIG;
172 if (l3type == AF_INET6)
173 /* use v4-mapped-v6 if no v6 addresses found */
174 hints.ai_flags |= AI_V4MAPPED | AI_ALL;
175
176 if (passive && host == NULL)
177 hints.ai_flags |= AI_PASSIVE;
178
179 /*
180 * Obtain local/remote address information
181 */
182 if ((rc = getaddrinfo(host, port, &hints, passive ? &local : &remote))) {
183 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s.\n",
184 layer4_name(l4type),
185 host? : (passive? "[loopback]" : "[localhost]"),
186 port, gai_strerror(rc));
187 return -E_ADDRESS_LOOKUP;
188 }
189
190 /*
191 * Iterate over all src/dst combination, exhausting dst first
192 */
193 for (src = local, dst = remote; src != NULL || dst != NULL; /* no op */ ) {
194 if (src && dst && src->ai_family == AF_INET
195 && dst->ai_family == AF_INET6) /* v4 -> v6 is not possible */
196 goto get_next_dst;
197
198 sockfd = socket(src ? src->ai_family : dst->ai_family, socktype, l4type);
199 if (sockfd < 0)
200 goto get_next_dst;
201
202 /*
203 * Set those options that need to be set before establishing the connection
204 */
205 /* Reuse the address on passive (listening) sockets to avoid failure on restart */
206 if (passive && setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1) {
207 PARA_ERROR_LOG("can not set SO_REUSEADDR: %s\n", strerror(errno));
208 return -ERRNO_TO_PARA_ERROR(errno);
209 }
210
211 if (src) {
212 if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
213 close(sockfd);
214 goto get_next_src;
215 }
216 if (!dst)
217 break; /* bind-only completed successfully */
218 }
219
220 if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
221 break; /* connection completed successfully */
222 close(sockfd);
223 get_next_dst:
224 if (dst && (dst = dst->ai_next))
225 continue;
226 get_next_src:
227 if (src && (src = src->ai_next))
228 dst = remote; /* restart inner loop */
229 }
230 if (local)
231 freeaddrinfo(local);
232 if (remote)
233 freeaddrinfo(remote);
234
235 if (src == NULL && dst == NULL) {
236 PARA_ERROR_LOG("can not create %s socket %s#%s.\n", layer4_name(l4type),
237 host? : (passive? "[loopback]" : "[localhost]"), port);
238 return -ERRNO_TO_PARA_ERROR(errno);
239 }
240 return sockfd;
241 }
242
243 /**
244 * Create a passive / listening socket.
245 * \param l3type The network-layer type (\p AF_xxx)
246 * \param l4type The transport-layer type (\p IPPROTO_xxx).
247 * \param port The decimal port number to listen on.
248 *
249 * \return Positive integer (socket descriptor) on success, negative value otherwise.
250 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
251 */
252 int para_listen(unsigned l3type, unsigned l4type, unsigned short port)
253 {
254 int ret, fd = makesock(l3type, l4type, 1, NULL, port);
255
256 if (fd > 0) {
257 ret = listen(fd, BACKLOG);
258 if (ret < 0) {
259 close(fd);
260 return -ERRNO_TO_PARA_ERROR(errno);
261 }
262 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
263 layer4_name(l4type), port, fd);
264 }
265 return fd;
266 }
267
268 /**
269 * Print numeric host and port number (beware - uses static char).
270 * \param sa The IPv4/IPv6 socket address to use.
271 * \param len The length of \p sa.
272 *
273 * \sa getnameinfo(3)
274 */
275 char *host_and_port(struct sockaddr *sa, socklen_t len)
276 {
277 static char output[NI_MAXHOST + NI_MAXSERV + 2];
278 char hbuf[NI_MAXHOST],
279 sbuf[NI_MAXSERV];
280 int ret;
281
282 ret = getnameinfo(sa, len, hbuf, sizeof(hbuf), sbuf, sizeof(sbuf),
283 NI_NUMERICHOST | NI_NUMERICSERV);
284 if (ret) {
285 PARA_WARNING_LOG("hostname lookup error (%s).\n", gai_strerror(ret));
286 sprintf(output, "(unknown)");
287 } else {
288 sprintf(output, "%s#%s", hbuf, sbuf);
289 }
290 return output;
291 }
292
293 /**
294 * Look up the local or remote side of a connected socket structure.
295 * \param fd The socket descriptor of the connected socket.
296 * \param getname Either \fn getsockname() for local, or \fn getpeername() for remote side.
297 *
298 * \return A static character string identifying hostname and port of the chosen side
299 * \sa getsockname(2), getpeername(2)
300 */
301 static char *__get_sock_name(int fd, int (*getname)(int, struct sockaddr*, socklen_t *))
302 {
303 struct sockaddr_storage ss;
304 socklen_t sslen = sizeof(ss);
305
306 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
307 static char *dont_know = "(don't know)";
308 PARA_ERROR_LOG("can not determine address from fd %d: %s\n", fd, strerror(errno));
309 return dont_know;
310 }
311
312 return host_and_port((struct sockaddr *)&ss, sslen);
313 }
314
315 char *local_name(int sockfd)
316 {
317 return __get_sock_name(sockfd, getsockname);
318 }
319
320 char *remote_name(int sockfd)
321 {
322 return __get_sock_name(sockfd, getpeername);
323 }
324
325 /*
326 * Send out a buffer, resend on short writes.
327 *
328 * \param fd The file descriptor.
329 * \param buf The buffer to be sent.
330 * \param len The length of \a buf.
331 *
332 * \return Standard. In any case, the number of bytes actually sent is stored
333 * in \a len.
334 */
335 static int sendall(int fd, const char *buf, size_t *len)
336 {
337 size_t total = *len;
338
339 assert(total);
340 *len = 0;
341 while (*len < total) {
342 int ret = send(fd, buf + *len, total - *len, 0);
343 if (ret == -1)
344 return -ERRNO_TO_PARA_ERROR(errno);
345 *len += ret;
346 }
347 return 1;
348 }
349
350 /**
351 * Encrypt and send a binary buffer.
352 *
353 * \param fd The file descriptor.
354 * \param buf The buffer to be encrypted and sent.
355 * \param len The length of \a buf.
356 *
357 * Check if encryption is available. If yes, encrypt the given buffer. Send
358 * out the buffer, encrypted or not, and try to resend the remaing part in case
359 * of short writes.
360 *
361 * \return Standard.
362 */
363 int send_bin_buffer(int fd, const char *buf, size_t len)
364 {
365 int ret;
366 crypt_function *cf = NULL;
367
368 if (!len)
369 PARA_CRIT_LOG("%s", "len == 0\n");
370 if (fd + 1 <= cda_size)
371 cf = crypt_data_array[fd].send;
372 if (cf) {
373 void *private = crypt_data_array[fd].private_data;
374 /* RC4 may write more than len to the output buffer */
375 unsigned char *outbuf = para_malloc(ROUND_UP(len, 8));
376 (*cf)(len, (unsigned char *)buf, outbuf, private);
377 ret = sendall(fd, (char *)outbuf, &len);
378 free(outbuf);
379 } else
380 ret = sendall(fd, buf, &len);
381 return ret;
382 }
383
384 /**
385 * Encrypt and send null terminated buffer.
386 *
387 * \param fd The file descriptor.
388 * \param buf The null-terminated buffer to be send.
389 *
390 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
391 *
392 * \return Standard.
393 */
394 int send_buffer(int fd, const char *buf)
395 {
396 return send_bin_buffer(fd, buf, strlen(buf));
397 }
398
399
400 /**
401 * Send and encrypt a buffer given by a format string.
402 *
403 * \param fd The file descriptor.
404 * \param fmt A format string.
405 *
406 * \return Standard.
407 */
408 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
409 {
410 char *msg;
411 int ret;
412
413 PARA_VSPRINTF(fmt, msg);
414 ret = send_buffer(fd, msg);
415 free(msg);
416 return ret;
417 }
418
419 /**
420 * Receive and decrypt.
421 *
422 * \param fd The file descriptor.
423 * \param buf The buffer to write the decrypted data to.
424 * \param size The size of \a buf.
425 *
426 * Receive at most \a size bytes from file descriptor \a fd. If encryption is
427 * available, decrypt the received buffer.
428 *
429 * \return The number of bytes received on success, negative on errors.
430 *
431 * \sa recv(2)
432 */
433 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
434 {
435 ssize_t n;
436 crypt_function *cf = NULL;
437
438 if (fd + 1 <= cda_size)
439 cf = crypt_data_array[fd].recv;
440 if (cf) {
441 unsigned char *tmp = para_malloc(size);
442 void *private = crypt_data_array[fd].private_data;
443 n = recv(fd, tmp, size, 0);
444 if (n > 0) {
445 size_t numbytes = n;
446 unsigned char *b = (unsigned char *)buf;
447 (*cf)(numbytes, tmp, b, private);
448 }
449 free(tmp);
450 } else
451 n = recv(fd, buf, size, 0);
452 if (n == -1)
453 return -ERRNO_TO_PARA_ERROR(errno);
454 return n;
455 }
456
457 /**
458 * Receive, decrypt and write terminating NULL byte.
459 *
460 * \param fd The file descriptor.
461 * \param buf The buffer to write the decrypted data to.
462 * \param size The size of \a buf.
463 *
464 * Read and decrypt at most \a size - 1 bytes from file descriptor \a fd and
465 * write a NULL byte at the end of the received data.
466 *
467 * \return The return value of the underlying call to \a recv_bin_buffer().
468 *
469 * \sa recv_bin_buffer()
470 */
471 int recv_buffer(int fd, char *buf, size_t size)
472 {
473 int n;
474
475 assert(size);
476 n = recv_bin_buffer(fd, buf, size - 1);
477 if (n >= 0)
478 buf[n] = '\0';
479 else
480 *buf = '\0';
481 return n;
482 }
483
484 /**
485 * Establish a tcp connection.
486 *
487 * \param host Hostname or IPv4 address.
488 * \param port The tcp port.
489 *
490 * \return Negative on errors, a valid file descriptor on success.
491 */
492 int tcp_connect(char *host, int port)
493 {
494 struct sockaddr_in addr;
495 struct hostent *he;
496 int ret, fd;
497
498 PARA_INFO_LOG("getting host info of %s\n", host);
499 /* FIXME: gethostbyname() is obsolete */
500 he = gethostbyname(host);
501 if (!he)
502 return -ERRNO_TO_PARA_ERROR(h_errno);
503 init_sockaddr(&addr, port, he);
504 ret = get_stream_socket(AF_INET);
505 if (ret < 0)
506 return ret;
507 fd = ret;
508 ret = PARA_CONNECT(fd, &addr);
509 if (ret >= 0)
510 return fd;
511 close(fd);
512 return ret;
513 }
514
515 /**
516 * A wrapper around socket(2).
517 *
518 * \param domain The communication domain that selects the protocol family.
519 *
520 * Create an IPv4 socket for sequenced, reliable, two-way, connection-based
521 * byte streams.
522 *
523 * \return The socket fd on success, negative on errors.
524 *
525 * \sa socket(2).
526 */
527 int get_stream_socket(int domain)
528 {
529 int fd = socket(domain, SOCK_STREAM, 0);
530
531 if (fd < 0)
532 return -ERRNO_TO_PARA_ERROR(errno);
533 return fd;
534 }
535
536 /**
537 * Wrapper around the accept system call.
538 *
539 * \param fd The listening socket.
540 * \param addr Structure which is filled in with the address of the peer socket.
541 * \param size Should contain the size of the structure pointed to by \a addr.
542 *
543 * Accept incoming connections on \a addr. Retry if interrupted.
544 *
545 * \return The new file descriptor on success, negative on errors.
546 *
547 * \sa accept(2).
548 */
549 int para_accept(int fd, void *addr, socklen_t size)
550 {
551 int new_fd;
552
553 do
554 new_fd = accept(fd, (struct sockaddr *) addr, &size);
555 while (new_fd < 0 && errno == EINTR);
556 return new_fd < 0? -ERRNO_TO_PARA_ERROR(errno) : new_fd;
557 }
558
559 /**
560 * prepare a structure for \p AF_UNIX socket addresses
561 *
562 * \param u pointer to the struct to be prepared
563 * \param name the socket pathname
564 *
565 * This just copies \a name to the sun_path component of \a u.
566 *
567 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
568 * than \p UNIX_PATH_MAX.
569 */
570 int init_unix_addr(struct sockaddr_un *u, const char *name)
571 {
572 if (strlen(name) >= UNIX_PATH_MAX)
573 return -E_NAME_TOO_LONG;
574 memset(u->sun_path, 0, UNIX_PATH_MAX);
575 u->sun_family = PF_UNIX;
576 strcpy(u->sun_path, name);
577 return 1;
578 }
579
580 /**
581 * Prepare, create, and bind a socket for local communication.
582 *
583 * \param name The socket pathname.
584 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
585 * \param mode The desired mode of the socket.
586 *
587 * This functions creates a local socket for sequenced, reliable,
588 * two-way, connection-based byte streams.
589 *
590 * \return The file descriptor, on success, negative on errors.
591 *
592 * \sa socket(2)
593 * \sa bind(2)
594 * \sa chmod(2)
595 */
596 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
597 mode_t mode)
598 {
599 int fd, ret;
600
601 ret = init_unix_addr(unix_addr, name);
602 if (ret < 0)
603 return ret;
604 ret = socket(PF_UNIX, SOCK_STREAM, 0);
605 if (ret < 0)
606 return -ERRNO_TO_PARA_ERROR(errno);
607 fd = ret;
608 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
609 if (ret < 0) {
610 ret = -ERRNO_TO_PARA_ERROR(errno);
611 goto err;
612 }
613 ret = -E_CHMOD;
614 if (chmod(name, mode) < 0)
615 goto err;
616 return fd;
617 err:
618 close(fd);
619 return ret;
620 }
621
622 #ifndef HAVE_UCRED
623 ssize_t send_cred_buffer(int sock, char *buf)
624 {
625 return send_buffer(sock, buf);
626 }
627 int recv_cred_buffer(int fd, char *buf, size_t size)
628 {
629 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
630 }
631 #else /* HAVE_UCRED */
632 /**
633 * send NULL terminated buffer and Unix credentials of the current process
634 *
635 * \param sock the socket file descriptor
636 * \param buf the buffer to be sent
637 *
638 * \return On success, this call returns the number of characters sent. On
639 * error, \p -E_SENDMSG is returned.
640 *
641 * \sa okir's Black Hats Manual
642 * \sa sendmsg(2)
643 */
644 ssize_t send_cred_buffer(int sock, char *buf)
645 {
646 char control[sizeof(struct cmsghdr) + 10];
647 struct msghdr msg;
648 struct cmsghdr *cmsg;
649 static struct iovec iov;
650 struct ucred c;
651 int ret;
652
653 /* Response data */
654 iov.iov_base = buf;
655 iov.iov_len = strlen(buf);
656 c.pid = getpid();
657 c.uid = getuid();
658 c.gid = getgid();
659 /* compose the message */
660 memset(&msg, 0, sizeof(msg));
661 msg.msg_iov = &iov;
662 msg.msg_iovlen = 1;
663 msg.msg_control = control;
664 msg.msg_controllen = sizeof(control);
665 /* attach the ucred struct */
666 cmsg = CMSG_FIRSTHDR(&msg);
667 cmsg->cmsg_level = SOL_SOCKET;
668 cmsg->cmsg_type = SCM_CREDENTIALS;
669 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
670 *(struct ucred *)CMSG_DATA(cmsg) = c;
671 msg.msg_controllen = cmsg->cmsg_len;
672 ret = sendmsg(sock, &msg, 0);
673 if (ret < 0)
674 ret = -E_SENDMSG;
675 return ret;
676 }
677
678 static void dispose_fds(int *fds, unsigned num)
679 {
680 int i;
681
682 for (i = 0; i < num; i++)
683 close(fds[i]);
684 }
685
686 /**
687 * receive a buffer and the Unix credentials of the sending process
688 *
689 * \param fd the socket file descriptor
690 * \param buf the buffer to store the message
691 * \param size the size of \a buffer
692 *
693 * \return negative on errors, the user id on success.
694 *
695 * \sa okir's Black Hats Manual
696 * \sa recvmsg(2)
697 */
698 int recv_cred_buffer(int fd, char *buf, size_t size)
699 {
700 char control[255];
701 struct msghdr msg;
702 struct cmsghdr *cmsg;
703 struct iovec iov;
704 int result = 0;
705 int yes = 1;
706 struct ucred cred;
707
708 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
709 memset(&msg, 0, sizeof(msg));
710 memset(buf, 0, size);
711 iov.iov_base = buf;
712 iov.iov_len = size;
713 msg.msg_iov = &iov;
714 msg.msg_iovlen = 1;
715 msg.msg_control = control;
716 msg.msg_controllen = sizeof(control);
717 if (recvmsg(fd, &msg, 0) < 0)
718 return -E_RECVMSG;
719 result = -E_SCM_CREDENTIALS;
720 cmsg = CMSG_FIRSTHDR(&msg);
721 while (cmsg) {
722 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
723 == SCM_CREDENTIALS) {
724 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
725 result = cred.uid;
726 } else
727 if (cmsg->cmsg_level == SOL_SOCKET
728 && cmsg->cmsg_type == SCM_RIGHTS) {
729 dispose_fds((int *) CMSG_DATA(cmsg),
730 (cmsg->cmsg_len - CMSG_LEN(0))
731 / sizeof(int));
732 }
733 cmsg = CMSG_NXTHDR(&msg, cmsg);
734 }
735 return result;
736 }
737 #endif /* HAVE_UCRED */
738
739 /**
740 * Create a tcp socket, bind it and listen on the given port.
741 *
742 * \param port The tcp port to listen on.
743 *
744 * \return The file descriptor of the created socket, negative on errors.
745 *
746 * \sa get_stream_socket()
747 * \sa setsockopt(2)
748 * \sa bind(2)
749 * \sa listen(2)
750 */
751 int tcp_listen(int port)
752 {
753 struct sockaddr_in my_addr;
754 int fd, ret = get_stream_socket(AF_INET);
755
756 if (ret < 0)
757 return ret;
758 fd = ret;
759 ret = 1;
760 ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &ret, sizeof(int));
761 if (ret < 0) {
762 ret = -ERRNO_TO_PARA_ERROR(errno);
763 goto err;
764 }
765 init_sockaddr(&my_addr, port, NULL);
766 ret = bind(fd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr));
767 if (ret < 0) {
768 ret = -ERRNO_TO_PARA_ERROR(errno);
769 goto err;
770 }
771 ret = listen(fd, BACKLOG);
772 if (ret < 0) {
773 ret = -ERRNO_TO_PARA_ERROR(errno);
774 goto err;
775 }
776 PARA_INFO_LOG("listening on port %d, fd %d\n", port, fd);
777 return fd;
778 err:
779 close(fd);
780 return ret;
781 }
782
783 /**
784 * receive a buffer and check for a pattern
785 *
786 * \param fd the file descriptor to receive from
787 * \param pattern the expected pattern
788 * \param bufsize the size of the internal buffer
789 *
790 * \return Positive if \a pattern was received, negative otherwise.
791 *
792 * This function creates a buffer of size \a bufsize and tries
793 * to receive at most \a bufsize bytes from file descriptor \a fd.
794 * If at least \p strlen(\a pattern) bytes were received, the beginning of
795 * the received buffer is compared with \a pattern, ignoring case.
796 *
797 * \sa recv_buffer()
798 * \sa strncasecmp(3)
799 */
800 int recv_pattern(int fd, const char *pattern, size_t bufsize)
801 {
802 size_t len = strlen(pattern);
803 char *buf = para_malloc(bufsize + 1);
804 int ret = -E_RECV_PATTERN, n = recv_buffer(fd, buf, bufsize);
805
806 if (n < len)
807 goto out;
808 if (strncasecmp(buf, pattern, len))
809 goto out;
810 ret = 1;
811 out:
812 if (ret < 0) {
813 PARA_NOTICE_LOG("n = %d, did not receive pattern '%s'\n", n, pattern);
814 if (n > 0)
815 PARA_NOTICE_LOG("recvd: %s\n", buf);
816 }
817 free(buf);
818 return ret;
819 }