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278 /* FIXME: gethostbyname() is obsolete */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