3dcd9c0be5884f59293d012c3e117ea61b83a282
[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 "para.h"
10 #include "net.h"
11 #include "string.h"
12 #include "error.h"
13
14
15 /** Information about one encrypted connection. */
16 struct crypt_data {
17 /** Function used to decrypt received data. */
18 crypt_function *recv;
19 /** Function used to encrypt data to be sent. */
20 crypt_function *send;
21 /**
22 * Context-dependent data (crypt keys), passed verbatim to the above
23 * crypt functions.
24 */
25 void *private_data;
26 };
27 /** Array holding per fd crypt data. */
28 static struct crypt_data *crypt_data_array;
29 /** Current size of the crypt data array. */
30 static unsigned cda_size = 0;
31
32 /**
33 * activate encryption for one file descriptor
34 *
35 * \param fd the file descriptor
36 * \param recv_f the function used for decrypting received data
37 * \param send_f the function used for encrypting before sending
38 * \param private_data user data supplied by the caller
39 */
40 void enable_crypt(int fd, crypt_function *recv_f, crypt_function *send_f,
41 void *private_data)
42 {
43 if (fd + 1 > cda_size) {
44 crypt_data_array = para_realloc(crypt_data_array,
45 (fd + 1) * sizeof(struct crypt_data));
46 memset(crypt_data_array + cda_size, 0,
47 (fd + 1 - cda_size) * sizeof(struct crypt_data));
48 cda_size = fd + 1;
49 }
50 crypt_data_array[fd].recv = recv_f;
51 crypt_data_array[fd].send = send_f;
52 crypt_data_array[fd].private_data = private_data;
53 PARA_INFO_LOG("rc4 encryption activated for fd %d\n", fd);
54 }
55
56 /**
57 * deactivate encryption for a given fd
58 *
59 * \param fd the file descriptor
60 *
61 * This must be called if and only if \p fd was activated via enable_crypt().
62 */
63 void disable_crypt(int fd)
64 {
65 if (cda_size < fd + 1)
66 return;
67 crypt_data_array[fd].recv = NULL;
68 crypt_data_array[fd].send = NULL;
69 crypt_data_array[fd].private_data = NULL;
70 }
71
72
73 /**
74 * initialize a struct sockaddr_in
75 *
76 * \param addr A pointer to the struct to be initialized
77 * \param port The port number to use
78 * \param he The address to use
79 *
80 * If \a he is null (server mode), \a addr->sin_addr is initialized with \p
81 * INADDR_ANY. Otherwise, the address given by \a he is copied to addr.
82 */
83 void init_sockaddr(struct sockaddr_in *addr, int port, const struct hostent *he)
84 {
85 /* host byte order */
86 addr->sin_family = AF_INET;
87 /* short, network byte order */
88 addr->sin_port = htons(port);
89 if (he)
90 addr->sin_addr = *((struct in_addr *)he->h_addr);
91 else
92 addr->sin_addr.s_addr = INADDR_ANY;
93 /* zero the rest of the struct */
94 memset(&addr->sin_zero, '\0', 8);
95 }
96
97 /*
98 * send out a buffer, resend on short writes
99 *
100 * \param fd the file descriptor
101 * \param buf The buffer to be sent
102 * \param len The length of \a buf
103 *
104 * Due to circumstances beyond your control, the kernel might not send all the
105 * data out in one chunk, and now, my friend, it's up to us to get the data out
106 * there (Beej's Guide to Network Programming).
107 *
108 * \return This function returns 1 on success and \a -E_SEND on errors. The
109 * number of bytes actually sent is stored upon successful return in \a len.
110 */
111 static int sendall(int fd, const char *buf, size_t *len)
112 {
113 size_t total = 0, bytesleft = *len; /* how many we have left to send */
114 int n = -1;
115
116 while (total < *len) {
117 n = send(fd, buf + total, bytesleft, 0);
118 if (n == -1)
119 break;
120 total += n;
121 bytesleft -= n;
122 if (total < *len)
123 PARA_DEBUG_LOG("short write (%zd byte(s) left)",
124 *len - total);
125 }
126 *len = total; /* return number actually sent here */
127 return n == -1? -E_SEND : 1; /* return 1 on success */
128 }
129
130 /**
131 * encrypt and send buffer
132 *
133 * \param fd: the file descriptor
134 * \param buf the buffer to be encrypted and sent
135 * \param len the length of \a buf
136 *
137 * Check if encrytpion is available. If yes, encrypt the given buffer. Send out
138 * the buffer, encrypted or not, and try to resend the remaing part in case of
139 * short writes.
140 *
141 * \return Positive on success, \p -E_SEND on errors.
142 */
143 int send_bin_buffer(int fd, const char *buf, size_t len)
144 {
145 int ret;
146 crypt_function *cf = NULL;
147
148 if (!len)
149 PARA_CRIT_LOG("%s", "len == 0\n");
150 if (fd + 1 <= cda_size)
151 cf = crypt_data_array[fd].send;
152 if (cf) {
153 void *private = crypt_data_array[fd].private_data;
154 /* RC4 may write more than len to the output buffer */
155 unsigned char *outbuf = para_malloc(ROUND_UP(len, 8));
156 (*cf)(len, (unsigned char *)buf, outbuf, private);
157 ret = sendall(fd, (char *)outbuf, &len);
158 free(outbuf);
159 } else
160 ret = sendall(fd, buf, &len);
161 return ret;
162 }
163
164 /**
165 * encrypt and send null terminated buffer.
166 *
167 * \param fd the file descriptor
168 * \param buf the null-terminated buffer to be send
169 *
170 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
171 *
172 * \return Positive on success, \p -E_SEND on errors.
173 */
174 int send_buffer(int fd, const char *buf)
175 {
176 return send_bin_buffer(fd, buf, strlen(buf));
177 }
178
179
180 /**
181 * send and encrypt a buffer given by a format string
182 *
183 * \param fd the file descriptor
184 * \param fmt a format string
185 *
186 * \return Positive on success, \p -E_SEND on errors.
187 */
188 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
189 {
190 char *msg;
191 int ret;
192
193 PARA_VSPRINTF(fmt, msg);
194 ret = send_buffer(fd, msg);
195 free(msg);
196 return ret;
197 }
198
199 /**
200 * receive and decrypt.
201 *
202 * \param fd the file descriptor
203 * \param buf the buffer to write the decrypted data to
204 * \param size the size of \a buf
205 *
206 * Receive at most \a size bytes from filedescriptor fd. If encryption is
207 * available, decrypt the received buffer.
208 *
209 * \return The number of bytes received on success. On receive errors, -E_RECV
210 * is returned. On crypt errors, the corresponding crypt error number is
211 * returned.
212 *
213 * \sa recv(2)
214 */
215 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
216 {
217 ssize_t n;
218 crypt_function *cf = NULL;
219
220 if (fd + 1 <= cda_size)
221 cf = crypt_data_array[fd].recv;
222 if (cf) {
223 unsigned char *tmp = para_malloc(size);
224 void *private = crypt_data_array[fd].private_data;
225 n = recv(fd, tmp, size, 0);
226 if (n > 0) {
227 size_t numbytes = n;
228 unsigned char *b = (unsigned char *)buf;
229 (*cf)(numbytes, tmp, b, private);
230 }
231 free(tmp);
232 } else
233 n = recv(fd, buf, size, 0);
234 if (n == -1)
235 n = -E_RECV;
236 return n;
237 }
238
239 /**
240 * receive, decrypt and write terminating NULL byte
241 *
242 * \param fd the file descriptor
243 * \param buf the buffer to write the decrypted data to
244 * \param size the size of \a buf
245 *
246 * Read and decrypt at most \a size - 1 bytes from file descriptor \a fd and
247 * write a NULL byte at the end of the received data.
248 *
249 * \return: The return value of the underlying call to \a recv_bin_buffer().
250 *
251 * \sa recv_bin_buffer()
252 */
253 int recv_buffer(int fd, char *buf, size_t size)
254 {
255 int n;
256
257 if (!size)
258 return -E_RECV;
259 n = recv_bin_buffer(fd, buf, size - 1);
260 if (n >= 0)
261 buf[n] = '\0';
262 else
263 *buf = '\0';
264 return n;
265 }
266
267 /**
268 * wrapper around gethostbyname
269 *
270 * \param host hostname or IPv4 address
271 * \param ret the hostent structure is returned here
272 *
273 * \return positive on success, negative on errors. On success, \a ret
274 * contains the return value of the underlying gethostbyname() call.
275 *
276 * \sa gethostbyname(2)
277 */
278 int get_host_info(char *host, struct hostent **ret)
279 {
280 PARA_INFO_LOG("getting host info of %s\n", host);
281 /* FIXME: gethostbyname() is obsolete */
282 *ret = gethostbyname(host);
283 return *ret? 1 : -E_HOST_INFO;
284 }
285
286 /**
287 * a wrapper around socket(2)
288 *
289 * Create an IPv4 socket for sequenced, reliable, two-way, connection-based
290 * byte streams.
291 *
292 * \return The socket fd on success, -E_SOCKET on errors.
293 *
294 * \sa socket(2)
295 */
296 int get_stream_socket(int domain)
297 {
298 int socket_fd;
299
300 if ((socket_fd = socket(domain, SOCK_STREAM, 0)) == -1)
301 return -E_SOCKET;
302 return socket_fd;
303 }
304
305 /**
306 * a wrapper around connect(2)
307 *
308 * \param fd the file descriptor
309 * \param their_addr the address to connect
310 *
311 * \return \p -E_CONNECT on errors, 1 on success
312 *
313 * \sa connect(2)
314 */
315 int para_connect(int fd, struct sockaddr_in *their_addr)
316 {
317 int ret;
318
319 if ((ret = connect(fd, (struct sockaddr *)their_addr,
320 sizeof(struct sockaddr))) == -1)
321 return -E_CONNECT;
322 return 1;
323 }
324
325 /**
326 * paraslash's wrapper around the accept system call
327 *
328 * \param fd the listening socket
329 * \param addr structure which is filled in with the address of the peer socket
330 * \param size should contain the size of the structure pointed to by \a addr
331 *
332 * Accept incoming connections on \a addr. Retry if interrupted.
333 *
334 * \return The new file descriptor on success, \a -E_ACCEPT on errors.
335 *
336 * \sa accept(2).
337 */
338 int para_accept(int fd, void *addr, socklen_t size)
339 {
340 int new_fd;
341
342 do
343 new_fd = accept(fd, (struct sockaddr *) addr, &size);
344 while (new_fd < 0 && errno == EINTR);
345 return new_fd < 0? -E_ACCEPT : new_fd;
346 }
347
348 static int setserversockopts(int socket_fd)
349 {
350 int yes = 1;
351
352 if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &yes,
353 sizeof(int)) == -1)
354 return -E_SETSOCKOPT;
355 return 1;
356 }
357
358 /**
359 * prepare a structure for \p AF_UNIX socket addresses
360 *
361 * \param u pointer to the struct to be prepared
362 * \param name the socket pathname
363 *
364 * This just copies \a name to the sun_path component of \a u.
365 *
366 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
367 * than \p UNIX_PATH_MAX.
368 */
369 int init_unix_addr(struct sockaddr_un *u, const char *name)
370 {
371 if (strlen(name) >= UNIX_PATH_MAX)
372 return -E_NAME_TOO_LONG;
373 memset(u->sun_path, 0, UNIX_PATH_MAX);
374 u->sun_family = PF_UNIX;
375 strcpy(u->sun_path, name);
376 return 1;
377 }
378
379 /**
380 * Prepare, create, and bind a socket for local communication.
381 *
382 * \param name The socket pathname.
383 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
384 * \param mode The desired mode of the socket.
385 *
386 * This functions creates a local socket for sequenced, reliable,
387 * two-way, connection-based byte streams.
388 *
389 * \return The file descriptor, on success, negative on errors.
390 *
391 * \sa socket(2)
392 * \sa bind(2)
393 * \sa chmod(2)
394 */
395 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
396 mode_t mode)
397 {
398 int fd, ret;
399
400 ret = init_unix_addr(unix_addr, name);
401 if (ret < 0)
402 return ret;
403 fd = socket(PF_UNIX, SOCK_STREAM, 0);
404 if (fd < 0)
405 return -E_SOCKET;
406 ret = -E_BIND;
407 if (bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX) < 0)
408 goto err;
409 ret = -E_CHMOD;
410 if (chmod(name, mode) < 0)
411 goto err;
412 return fd;
413 err:
414 close(fd);
415 return ret;
416 }
417
418 #ifndef HAVE_UCRED
419 ssize_t send_cred_buffer(int sock, char *buf)
420 {
421 return send_buffer(sock, buf);
422 }
423 int recv_cred_buffer(int fd, char *buf, size_t size)
424 {
425 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
426 }
427 #else /* HAVE_UCRED */
428 /**
429 * send NULL terminated buffer and Unix credentials of the current process
430 *
431 * \param sock the socket file descriptor
432 * \param buf the buffer to be sent
433 *
434 * \return On success, this call returns the number of characters sent. On
435 * error, \p -E_SENDMSG ist returned.
436 *
437 * \sa okir's Black Hats Manual
438 * \sa sendmsg(2)
439 */
440 ssize_t send_cred_buffer(int sock, char *buf)
441 {
442 char control[sizeof(struct cmsghdr) + 10];
443 struct msghdr msg;
444 struct cmsghdr *cmsg;
445 static struct iovec iov;
446 struct ucred c;
447 int ret;
448
449 /* Response data */
450 iov.iov_base = buf;
451 iov.iov_len = strlen(buf);
452 c.pid = getpid();
453 c.uid = getuid();
454 c.gid = getgid();
455 /* compose the message */
456 memset(&msg, 0, sizeof(msg));
457 msg.msg_iov = &iov;
458 msg.msg_iovlen = 1;
459 msg.msg_control = control;
460 msg.msg_controllen = sizeof(control);
461 /* attach the ucred struct */
462 cmsg = CMSG_FIRSTHDR(&msg);
463 cmsg->cmsg_level = SOL_SOCKET;
464 cmsg->cmsg_type = SCM_CREDENTIALS;
465 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
466 *(struct ucred *)CMSG_DATA(cmsg) = c;
467 msg.msg_controllen = cmsg->cmsg_len;
468 ret = sendmsg(sock, &msg, 0);
469 if (ret < 0)
470 ret = -E_SENDMSG;
471 return ret;
472 }
473
474 static void dispose_fds(int *fds, unsigned num)
475 {
476 int i;
477
478 for (i = 0; i < num; i++)
479 close(fds[i]);
480 }
481
482 /**
483 * receive a buffer and the Unix credentials of the sending process
484 *
485 * \param fd the socket file descriptor
486 * \param buf the buffer to store the message
487 * \param size the size of \a buffer
488 *
489 * \return negative on errors, the user id on success.
490 *
491 * \sa okir's Black Hats Manual
492 * \sa recvmsg(2)
493 */
494 int recv_cred_buffer(int fd, char *buf, size_t size)
495 {
496 char control[255];
497 struct msghdr msg;
498 struct cmsghdr *cmsg;
499 struct iovec iov;
500 int result = 0;
501 int yes = 1;
502 struct ucred cred;
503
504 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
505 memset(&msg, 0, sizeof(msg));
506 memset(buf, 0, size);
507 iov.iov_base = buf;
508 iov.iov_len = size;
509 msg.msg_iov = &iov;
510 msg.msg_iovlen = 1;
511 msg.msg_control = control;
512 msg.msg_controllen = sizeof(control);
513 if (recvmsg(fd, &msg, 0) < 0)
514 return -E_RECVMSG;
515 result = -E_SCM_CREDENTIALS;
516 cmsg = CMSG_FIRSTHDR(&msg);
517 while (cmsg) {
518 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
519 == SCM_CREDENTIALS) {
520 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
521 result = cred.uid;
522 } else
523 if (cmsg->cmsg_level == SOL_SOCKET
524 && cmsg->cmsg_type == SCM_RIGHTS) {
525 dispose_fds((int *) CMSG_DATA(cmsg),
526 (cmsg->cmsg_len - CMSG_LEN(0))
527 / sizeof(int));
528 }
529 cmsg = CMSG_NXTHDR(&msg, cmsg);
530 }
531 return result;
532 }
533 #endif /* HAVE_UCRED */
534
535 /** how many pending connections queue will hold */
536 #define BACKLOG 10
537
538 /**
539 * create a socket, bind it and listen
540 *
541 * \param port the tcp port to listen on
542 *
543 * \return The file descriptor of the created socket, negative
544 * on errors.
545 *
546 * \sa get_stream_socket()
547 * \sa setsockopt(2)
548 * \sa bind(2)
549 * \sa listen(2)
550 */
551 int init_tcp_socket(int port)
552 {
553 struct sockaddr_in my_addr;
554 int fd, ret = get_stream_socket(AF_INET);
555
556 if (ret < 0)
557 return ret;
558 fd = ret;
559 ret = setserversockopts(fd);
560 if (ret < 0)
561 goto err;
562 init_sockaddr(&my_addr, port, NULL);
563 ret = -E_BIND;
564 if (bind(fd, (struct sockaddr *)&my_addr,
565 sizeof(struct sockaddr)) == -1) {
566 PARA_CRIT_LOG("bind error: %s\n", strerror(errno));
567 goto err;
568 }
569 ret = -E_LISTEN;
570 if (listen(fd, BACKLOG) == -1)
571 goto err;
572 PARA_INFO_LOG("listening on port %d, fd %d\n", port, fd);
573 return fd;
574 err:
575 close(fd);
576 return ret;
577 }
578
579 /**
580 * receive a buffer and check for a pattern
581 *
582 * \param fd the file descriptor to receive from
583 * \param pattern the expected pattern
584 * \param bufsize the size of the internal buffer
585 *
586 * \return Positive if \a pattern was received, negative otherwise.
587 *
588 * This function creates a buffer of size \a bufsize and tries
589 * to receive at most \a bufsize bytes from file descriptor \a fd.
590 * If at least \p strlen(\a pattern) bytes were received, the beginning of
591 * the received buffer is compared with \a pattern, ignoring case.
592 *
593 * \sa recv_buffer()
594 * \sa strncasecmp(3)
595 */
596 int recv_pattern(int fd, const char *pattern, size_t bufsize)
597 {
598 size_t len = strlen(pattern);
599 char *buf = para_malloc(bufsize + 1);
600 int ret = -E_RECV_PATTERN, n = recv_buffer(fd, buf, bufsize);
601
602 if (n < len)
603 goto out;
604 if (strncasecmp(buf, pattern, len))
605 goto out;
606 ret = 1;
607 out:
608 if (ret < 0) {
609 PARA_NOTICE_LOG("n = %d, did not receive pattern '%s'\n", n, pattern);
610 if (n > 0)
611 PARA_NOTICE_LOG("recvd: %s\n", buf);
612 }
613 free(buf);
614 return ret;
615 }