Rename init_tcp_socket() to tcp_listen() and further net.c cleanups.
[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> /* hostent */
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 * Send out a buffer, resend on short writes.
101 *
102 * \param fd The file descriptor.
103 * \param buf The buffer to be sent.
104 * \param len The length of \a buf.
105 *
106 * \return Standard. In any case, the number of bytes actually sent is stored
107 * in \a len.
108 */
109 static int sendall(int fd, const char *buf, size_t *len)
110 {
111 size_t total = *len;
112
113 assert(total);
114 *len = 0;
115 while (*len < total) {
116 int ret = send(fd, buf + *len, total - *len, 0);
117 if (ret == -1)
118 return -ERRNO_TO_PARA_ERROR(errno);
119 *len += ret;
120 }
121 return 1;
122 }
123
124 /**
125 * Encrypt and send a binary buffer.
126 *
127 * \param fd The file descriptor.
128 * \param buf The buffer to be encrypted and sent.
129 * \param len The length of \a buf.
130 *
131 * Check if encryption is available. If yes, encrypt the given buffer. Send
132 * out the buffer, encrypted or not, and try to resend the remaing part in case
133 * of short writes.
134 *
135 * \return Standard.
136 */
137 int send_bin_buffer(int fd, const char *buf, size_t len)
138 {
139 int ret;
140 crypt_function *cf = NULL;
141
142 if (!len)
143 PARA_CRIT_LOG("%s", "len == 0\n");
144 if (fd + 1 <= cda_size)
145 cf = crypt_data_array[fd].send;
146 if (cf) {
147 void *private = crypt_data_array[fd].private_data;
148 /* RC4 may write more than len to the output buffer */
149 unsigned char *outbuf = para_malloc(ROUND_UP(len, 8));
150 (*cf)(len, (unsigned char *)buf, outbuf, private);
151 ret = sendall(fd, (char *)outbuf, &len);
152 free(outbuf);
153 } else
154 ret = sendall(fd, buf, &len);
155 return ret;
156 }
157
158 /**
159 * Encrypt and send null terminated buffer.
160 *
161 * \param fd The file descriptor.
162 * \param buf The null-terminated buffer to be send.
163 *
164 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
165 *
166 * \return Standard.
167 */
168 int send_buffer(int fd, const char *buf)
169 {
170 return send_bin_buffer(fd, buf, strlen(buf));
171 }
172
173
174 /**
175 * Send and encrypt a buffer given by a format string.
176 *
177 * \param fd The file descriptor.
178 * \param fmt A format string.
179 *
180 * \return Standard.
181 */
182 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
183 {
184 char *msg;
185 int ret;
186
187 PARA_VSPRINTF(fmt, msg);
188 ret = send_buffer(fd, msg);
189 free(msg);
190 return ret;
191 }
192
193 /**
194 * Receive and decrypt.
195 *
196 * \param fd The file descriptor.
197 * \param buf The buffer to write the decrypted data to.
198 * \param size The size of \a buf.
199 *
200 * Receive at most \a size bytes from file descriptor \a fd. If encryption is
201 * available, decrypt the received buffer.
202 *
203 * \return The number of bytes received on success, negative on errors.
204 *
205 * \sa recv(2)
206 */
207 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
208 {
209 ssize_t n;
210 crypt_function *cf = NULL;
211
212 if (fd + 1 <= cda_size)
213 cf = crypt_data_array[fd].recv;
214 if (cf) {
215 unsigned char *tmp = para_malloc(size);
216 void *private = crypt_data_array[fd].private_data;
217 n = recv(fd, tmp, size, 0);
218 if (n > 0) {
219 size_t numbytes = n;
220 unsigned char *b = (unsigned char *)buf;
221 (*cf)(numbytes, tmp, b, private);
222 }
223 free(tmp);
224 } else
225 n = recv(fd, buf, size, 0);
226 if (n == -1)
227 return -ERRNO_TO_PARA_ERROR(errno);
228 return n;
229 }
230
231 /**
232 * Receive, decrypt and write terminating NULL byte.
233 *
234 * \param fd The file descriptor.
235 * \param buf The buffer to write the decrypted data to.
236 * \param size The size of \a buf.
237 *
238 * Read and decrypt at most \a size - 1 bytes from file descriptor \a fd and
239 * write a NULL byte at the end of the received data.
240 *
241 * \return The return value of the underlying call to \a recv_bin_buffer().
242 *
243 * \sa recv_bin_buffer()
244 */
245 int recv_buffer(int fd, char *buf, size_t size)
246 {
247 int n;
248
249 assert(size);
250 n = recv_bin_buffer(fd, buf, size - 1);
251 if (n >= 0)
252 buf[n] = '\0';
253 else
254 *buf = '\0';
255 return n;
256 }
257
258 /**
259 * Establish a tcp connection.
260 *
261 * \param host Hostname or IPv4 address.
262 * \param port The tcp port.
263 *
264 * \return Negative on errors, a valid file descriptor on success.
265 */
266 int tcp_connect(char *host, int port)
267 {
268 struct sockaddr_in addr;
269 struct hostent *he;
270 int ret, fd;
271
272 PARA_INFO_LOG("getting host info of %s\n", host);
273 /* FIXME: gethostbyname() is obsolete */
274 he = gethostbyname(host);
275 if (!he)
276 return -ERRNO_TO_PARA_ERROR(h_errno);
277 init_sockaddr(&addr, port, he);
278 ret = get_stream_socket(AF_INET);
279 if (ret < 0)
280 return ret;
281 fd = ret;
282 ret = PARA_CONNECT(fd, &addr);
283 if (ret >= 0)
284 return fd;
285 close(fd);
286 return ret;
287 }
288
289 /**
290 * A wrapper around socket(2).
291 *
292 * \param domain The communication domain that selects the protocol family.
293 *
294 * Create an IPv4 socket for sequenced, reliable, two-way, connection-based
295 * byte streams.
296 *
297 * \return The socket fd on success, negative on errors.
298 *
299 * \sa socket(2).
300 */
301 int get_stream_socket(int domain)
302 {
303 int fd = socket(domain, SOCK_STREAM, 0);
304
305 if (fd < 0)
306 return -ERRNO_TO_PARA_ERROR(errno);
307 return fd;
308 }
309
310 /**
311 * Wrapper around the accept system call.
312 *
313 * \param fd The listening socket.
314 * \param addr Structure which is filled in with the address of the peer socket.
315 * \param size Should contain the size of the structure pointed to by \a addr.
316 *
317 * Accept incoming connections on \a addr. Retry if interrupted.
318 *
319 * \return The new file descriptor on success, negative on errors.
320 *
321 * \sa accept(2).
322 */
323 int para_accept(int fd, void *addr, socklen_t size)
324 {
325 int new_fd;
326
327 do
328 new_fd = accept(fd, (struct sockaddr *) addr, &size);
329 while (new_fd < 0 && errno == EINTR);
330 return new_fd < 0? -ERRNO_TO_PARA_ERROR(errno) : new_fd;
331 }
332
333 /**
334 * prepare a structure for \p AF_UNIX socket addresses
335 *
336 * \param u pointer to the struct to be prepared
337 * \param name the socket pathname
338 *
339 * This just copies \a name to the sun_path component of \a u.
340 *
341 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
342 * than \p UNIX_PATH_MAX.
343 */
344 int init_unix_addr(struct sockaddr_un *u, const char *name)
345 {
346 if (strlen(name) >= UNIX_PATH_MAX)
347 return -E_NAME_TOO_LONG;
348 memset(u->sun_path, 0, UNIX_PATH_MAX);
349 u->sun_family = PF_UNIX;
350 strcpy(u->sun_path, name);
351 return 1;
352 }
353
354 /**
355 * Prepare, create, and bind a socket for local communication.
356 *
357 * \param name The socket pathname.
358 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
359 * \param mode The desired mode of the socket.
360 *
361 * This functions creates a local socket for sequenced, reliable,
362 * two-way, connection-based byte streams.
363 *
364 * \return The file descriptor, on success, negative on errors.
365 *
366 * \sa socket(2)
367 * \sa bind(2)
368 * \sa chmod(2)
369 */
370 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
371 mode_t mode)
372 {
373 int fd, ret;
374
375 ret = init_unix_addr(unix_addr, name);
376 if (ret < 0)
377 return ret;
378 ret = socket(PF_UNIX, SOCK_STREAM, 0);
379 if (ret < 0)
380 return -ERRNO_TO_PARA_ERROR(errno);
381 fd = ret;
382 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
383 if (ret < 0) {
384 ret = -ERRNO_TO_PARA_ERROR(errno);
385 goto err;
386 }
387 ret = -E_CHMOD;
388 if (chmod(name, mode) < 0)
389 goto err;
390 return fd;
391 err:
392 close(fd);
393 return ret;
394 }
395
396 #ifndef HAVE_UCRED
397 ssize_t send_cred_buffer(int sock, char *buf)
398 {
399 return send_buffer(sock, buf);
400 }
401 int recv_cred_buffer(int fd, char *buf, size_t size)
402 {
403 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
404 }
405 #else /* HAVE_UCRED */
406 /**
407 * send NULL terminated buffer and Unix credentials of the current process
408 *
409 * \param sock the socket file descriptor
410 * \param buf the buffer to be sent
411 *
412 * \return On success, this call returns the number of characters sent. On
413 * error, \p -E_SENDMSG is returned.
414 *
415 * \sa okir's Black Hats Manual
416 * \sa sendmsg(2)
417 */
418 ssize_t send_cred_buffer(int sock, char *buf)
419 {
420 char control[sizeof(struct cmsghdr) + 10];
421 struct msghdr msg;
422 struct cmsghdr *cmsg;
423 static struct iovec iov;
424 struct ucred c;
425 int ret;
426
427 /* Response data */
428 iov.iov_base = buf;
429 iov.iov_len = strlen(buf);
430 c.pid = getpid();
431 c.uid = getuid();
432 c.gid = getgid();
433 /* compose the message */
434 memset(&msg, 0, sizeof(msg));
435 msg.msg_iov = &iov;
436 msg.msg_iovlen = 1;
437 msg.msg_control = control;
438 msg.msg_controllen = sizeof(control);
439 /* attach the ucred struct */
440 cmsg = CMSG_FIRSTHDR(&msg);
441 cmsg->cmsg_level = SOL_SOCKET;
442 cmsg->cmsg_type = SCM_CREDENTIALS;
443 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
444 *(struct ucred *)CMSG_DATA(cmsg) = c;
445 msg.msg_controllen = cmsg->cmsg_len;
446 ret = sendmsg(sock, &msg, 0);
447 if (ret < 0)
448 ret = -E_SENDMSG;
449 return ret;
450 }
451
452 static void dispose_fds(int *fds, unsigned num)
453 {
454 int i;
455
456 for (i = 0; i < num; i++)
457 close(fds[i]);
458 }
459
460 /**
461 * receive a buffer and the Unix credentials of the sending process
462 *
463 * \param fd the socket file descriptor
464 * \param buf the buffer to store the message
465 * \param size the size of \a buffer
466 *
467 * \return negative on errors, the user id on success.
468 *
469 * \sa okir's Black Hats Manual
470 * \sa recvmsg(2)
471 */
472 int recv_cred_buffer(int fd, char *buf, size_t size)
473 {
474 char control[255];
475 struct msghdr msg;
476 struct cmsghdr *cmsg;
477 struct iovec iov;
478 int result = 0;
479 int yes = 1;
480 struct ucred cred;
481
482 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
483 memset(&msg, 0, sizeof(msg));
484 memset(buf, 0, size);
485 iov.iov_base = buf;
486 iov.iov_len = size;
487 msg.msg_iov = &iov;
488 msg.msg_iovlen = 1;
489 msg.msg_control = control;
490 msg.msg_controllen = sizeof(control);
491 if (recvmsg(fd, &msg, 0) < 0)
492 return -E_RECVMSG;
493 result = -E_SCM_CREDENTIALS;
494 cmsg = CMSG_FIRSTHDR(&msg);
495 while (cmsg) {
496 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
497 == SCM_CREDENTIALS) {
498 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
499 result = cred.uid;
500 } else
501 if (cmsg->cmsg_level == SOL_SOCKET
502 && cmsg->cmsg_type == SCM_RIGHTS) {
503 dispose_fds((int *) CMSG_DATA(cmsg),
504 (cmsg->cmsg_len - CMSG_LEN(0))
505 / sizeof(int));
506 }
507 cmsg = CMSG_NXTHDR(&msg, cmsg);
508 }
509 return result;
510 }
511 #endif /* HAVE_UCRED */
512
513 /** how many pending connections queue will hold */
514 #define BACKLOG 10
515
516 /**
517 * Create a tcp socket, bind it and listen on the given port.
518 *
519 * \param Port the tcp port to listen on.
520 *
521 * \return The file descriptor of the created socket, negative on errors.
522 *
523 * \sa get_stream_socket()
524 * \sa setsockopt(2)
525 * \sa bind(2)
526 * \sa listen(2)
527 */
528 int tcp_listen(int port)
529 {
530 struct sockaddr_in my_addr;
531 int fd, ret = get_stream_socket(AF_INET);
532
533 if (ret < 0)
534 return ret;
535 fd = ret;
536 ret = 1;
537 ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &ret, sizeof(int));
538 if (ret < 0) {
539 ret = -ERRNO_TO_PARA_ERROR(errno);
540 goto err;
541 }
542 init_sockaddr(&my_addr, port, NULL);
543 ret = bind(fd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr));
544 if (ret < 0) {
545 ret = -ERRNO_TO_PARA_ERROR(errno);
546 goto err;
547 }
548 ret = listen(fd, BACKLOG);
549 if (ret < 0) {
550 ret = -ERRNO_TO_PARA_ERROR(errno);
551 goto err;
552 }
553 PARA_INFO_LOG("listening on port %d, fd %d\n", port, fd);
554 return fd;
555 err:
556 close(fd);
557 return ret;
558 }
559
560 /**
561 * receive a buffer and check for a pattern
562 *
563 * \param fd the file descriptor to receive from
564 * \param pattern the expected pattern
565 * \param bufsize the size of the internal buffer
566 *
567 * \return Positive if \a pattern was received, negative otherwise.
568 *
569 * This function creates a buffer of size \a bufsize and tries
570 * to receive at most \a bufsize bytes from file descriptor \a fd.
571 * If at least \p strlen(\a pattern) bytes were received, the beginning of
572 * the received buffer is compared with \a pattern, ignoring case.
573 *
574 * \sa recv_buffer()
575 * \sa strncasecmp(3)
576 */
577 int recv_pattern(int fd, const char *pattern, size_t bufsize)
578 {
579 size_t len = strlen(pattern);
580 char *buf = para_malloc(bufsize + 1);
581 int ret = -E_RECV_PATTERN, n = recv_buffer(fd, buf, bufsize);
582
583 if (n < len)
584 goto out;
585 if (strncasecmp(buf, pattern, len))
586 goto out;
587 ret = 1;
588 out:
589 if (ret < 0) {
590 PARA_NOTICE_LOG("n = %d, did not receive pattern '%s'\n", n, pattern);
591 if (n > 0)
592 PARA_NOTICE_LOG("recvd: %s\n", buf);
593 }
594 free(buf);
595 return ret;
596 }