fix dccp sender/receiver
[paraslash.git] / net.c
1 /*
2 * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18
19 /** \file net.c networking-related helper functions */
20
21 #include "para.h"
22 #include "net.h"
23 #include "string.h"
24 #include <netdb.h>
25 #include "error.h"
26
27 extern void (*crypt_function_recv)(unsigned long len, const unsigned char *indata, unsigned char *outdata);
28 extern void (*crypt_function_send)(unsigned long len, const unsigned char *indata, unsigned char *outdata);
29
30
31 /**
32 * initialize a struct sockaddr_in
33 * @param addr A pointer to the struct to be initialized
34 * @param port The port number to use
35 * @param he The address to use
36 *
37 * If \a he is null (server mode), \a addr->sin_addr is initialized with \p INADDR_ANY.
38 * Otherwise, the address given by \a he is copied to addr.
39 */
40 void init_sockaddr(struct sockaddr_in *addr, int port, const struct hostent *he)
41 {
42 /* host byte order */
43 addr->sin_family = AF_INET;
44 /* short, network byte order */
45 addr->sin_port = htons(port);
46 if (he)
47 addr->sin_addr = *((struct in_addr *)he->h_addr);
48 else
49 addr->sin_addr.s_addr = INADDR_ANY;
50 /* zero the rest of the struct */
51 memset(&addr->sin_zero, '\0', 8);
52 }
53
54 /*
55 * send out a buffer, resend on short writes
56 * @param fd the file descriptor
57 * @param buf The buffer to be sent
58 * @len The length of \a buf
59 *
60 * Due to circumstances beyond your control, the kernel might not send all the
61 * data out in one chunk, and now, my friend, it's up to us to get the data out
62 * there (Beej's Guide to Network Programming).
63 */
64 static int sendall(int fd, const char *buf, size_t *len)
65 {
66 int total = 0; /* how many bytes we've sent */
67 int bytesleft = *len; /* how many we have left to send */
68 int n = -1;
69
70 while (total < *len) {
71 n = send(fd, buf + total, bytesleft, 0);
72 if (n == -1)
73 break;
74 total += n;
75 bytesleft -= n;
76 if (total < *len)
77 PARA_DEBUG_LOG("short write (%zd byte(s) left)",
78 *len - total);
79 }
80 *len = total; /* return number actually sent here */
81 return n == -1? -E_SEND : 1; /* return 1 on success */
82 }
83
84 /**
85 * encrypt and send buffer
86 * @param fd: the file descriptor
87 * @param buf the buffer to be encrypted and sent
88 * @param len the length of \a buf
89 *
90 * Check if encrytion is available. If yes, encrypt the given buffer. Send out
91 * the buffer, encrypted or not, and try to resend the remaing part in case of
92 * short writes.
93 *
94 * @return Positive on success, \p -E_SEND on errors.
95 */
96 int send_bin_buffer(int fd, const char *buf, size_t len)
97 {
98 int ret;
99
100 if (!len)
101 PARA_CRIT_LOG("%s", "len == 0\n");
102 if (crypt_function_send) {
103 unsigned char *outbuf = para_malloc(len);
104 crypt_function_send(len, (unsigned char *)buf, outbuf);
105 ret = sendall(fd, (char *)outbuf, &len);
106 free(outbuf);
107 } else
108 ret = sendall(fd, buf, &len);
109 return ret;
110 }
111
112 /**
113 * encrypt and send null terminated buffer.
114 * @param fd the file descriptor
115 * @param buf the null-terminated buffer to be send
116 *
117 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
118 *
119 * @return Positive on success, \p -E_SEND on errors.
120 */
121 int send_buffer(int fd, const char *buf)
122 {
123 return send_bin_buffer(fd, buf, strlen(buf));
124 }
125
126
127 /**
128 * send and encrypt a buffer given by a format string
129 * @param fd the file descriptor
130 * @param fmt a format string
131 *
132 * @return Positive on success, \p -E_SEND on errors.
133 */
134 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
135 {
136 char *msg;
137 int ret;
138
139 PARA_VSPRINTF(fmt, msg);
140 ret = send_buffer(fd, msg);
141 free(msg);
142 return ret;
143 }
144
145 /**
146 * receive and decrypt.
147 *
148 * @param fd the file descriptor
149 * @param buf the buffer to write the decrypted data to
150 * @param size the size of @param buf
151 *
152 * Receive at most \a size bytes from filedescriptor fd. If encrytion is
153 * available, decrypt the received buffer.
154 *
155 * @return the number of bytes received on success. On receive errors, -E_RECV
156 * is returned. On crypt errors, the corresponding crypt error number is
157 * returned.
158 * \sa recv(2)
159 */
160 __must_check int recv_bin_buffer(int fd, char *buf, ssize_t size)
161 {
162 int n;
163
164 if (crypt_function_recv) {
165 unsigned char *tmp = para_malloc(size);
166 n = recv(fd, tmp, size, 0);
167 if (n > 0)
168 crypt_function_recv(n, tmp, (unsigned char *)buf);
169 free(tmp);
170 } else
171 n = recv(fd, buf, size, 0);
172 if (n == -1)
173 n = -E_RECV;
174 return n;
175 }
176
177 /**
178 * receive, decrypt and write terminating NULL byte
179 *
180 * @param fd the file descriptor
181 * @param buf the buffer to write the decrypted data to
182 * @param size the size of \a buf
183 *
184 * Read and decrypt at most size - 1 bytes from file descriptor \a fd and write
185 * a NULL byte at the end of the received data.
186 *
187 */
188 int recv_buffer(int fd, char *buf, ssize_t size)
189 {
190 int n;
191
192 n = recv_bin_buffer(fd, buf, size - 1);
193 if (n >= 0)
194 buf[n] = '\0';
195 else
196 *buf = '\0';
197 return n;
198 }
199
200 /**
201 * wrapper around gethostbyname
202 *
203 * @param host hostname or IPv4 address
204 * \return The hostent structure or a NULL pointer if an error occurs
205 * \sa gethostbyname(2)
206 */
207 struct hostent *get_host_info(char *host)
208 {
209 PARA_INFO_LOG("getting host info of %s\n", host);
210 /* FIXME: gethostbyname() is obsolete */
211 return gethostbyname(host);
212 }
213
214 /**
215 * a wrapper around socket(2)
216 *
217 * Create an IPv4 socket for sequenced, reliable, two-way, connection-based
218 * byte streams.
219 *
220 * @return The socket fd on success, -E_SOCKET on errors.
221 * \sa socket(2)
222 */
223 int get_socket(void)
224 {
225 int socket_fd;
226
227 if ((socket_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
228 return -E_SOCKET;
229 return socket_fd;
230 }
231
232 /**
233 * a wrapper around connect(2)
234 *
235 * @param fd the file descriptor
236 * @param their_addr the address to connect
237 *
238 * @return \p -E_CONNECT on errors, 1 on success
239 * \sa connect(2)
240 */
241 int para_connect(int fd, struct sockaddr_in *their_addr)
242 {
243 int ret;
244
245 if ((ret = connect(fd, (struct sockaddr *)their_addr,
246 sizeof(struct sockaddr))) == -1)
247 return -E_CONNECT;
248 return 1;
249 }
250
251 /**
252 * paraslash's wrapper around the accept system call
253 *
254 * @param fd the listening socket
255 * @param addr structure which is filled in with the address of the peer socket
256 * @param size should contain the size of the structure pointed to by \a addr
257 *
258 * \sa accept(2).
259 */
260 int para_accept(int fd, void *addr, socklen_t size)
261 {
262 int new_fd;
263
264 new_fd = accept(fd, (struct sockaddr *) addr, &size);
265 return new_fd == -1? -E_ACCEPT : new_fd;
266 }
267
268 static int setserversockopts(int socket_fd)
269 {
270 int yes = 1;
271
272 if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &yes,
273 sizeof(int)) == -1)
274 return -E_SETSOCKOPT;
275 return 1;
276 }
277
278 static int do_bind(int socket_fd, struct sockaddr_in *my_addr)
279 {
280 if (bind(socket_fd, (struct sockaddr *)my_addr,
281 sizeof(struct sockaddr)) == -1)
282 return -E_BIND;
283 return 1;
284 }
285
286 /**
287 * prepare a structure for \p AF_UNIX socket addresses
288 *
289 * \param u pointer to the struct to be prepared
290 * \param name the socket pathname
291 *
292 * This just copies \a name to the sun_path component of \a u.
293 *
294 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
295 * than \p UNIX_PATH_MAX.
296 */
297 int init_unix_addr(struct sockaddr_un *u, const char *name)
298 {
299 if (strlen(name) >= UNIX_PATH_MAX)
300 return -E_NAME_TOO_LONG;
301 memset(u->sun_path, 0, UNIX_PATH_MAX);
302 u->sun_family = PF_UNIX;
303 strcpy(u->sun_path, name);
304 return 1;
305 }
306
307 /**
308 * prepare, create, and bind and socket for local communication
309 *
310 * \param name the socket pathname
311 * \param unix_addr pointer to the \p AF_UNIX socket structure
312 * \param mode the desired mode of the socket
313 *
314 * This functions creates a local socket for sequenced, reliable,
315 * two-way, connection-based byte streams.
316 * \sa socket(2)
317 * \sa bind(2)
318 * \sa chmod(2)
319 */
320 int create_pf_socket(const char *name, struct sockaddr_un *unix_addr, int mode)
321 {
322 int fd, ret;
323
324 fd = socket(PF_UNIX, SOCK_STREAM, 0);
325 if (fd < 0)
326 return -E_SOCKET;
327 // unlink(name);
328 ret = init_unix_addr(unix_addr, name);
329 if (ret < 0)
330 return ret;
331 if (bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX) < 0)
332 return -E_BIND;
333 if (chmod(name, mode) < 0)
334 return -E_CHMOD;
335 return fd;
336 }
337
338 #ifndef HAVE_UCRED
339 struct ucred {
340 uid_t uid, pid, gid;
341 };
342 ssize_t send_cred_buffer(int sock, char *buf)
343 {
344 return send_buffer(sock, buf);
345 }
346 int recv_cred_buffer(int fd, char *buf, size_t size)
347 {
348 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
349 }
350 #else /* HAVE_UCRED */
351 /**
352 * send NULL terminated buffer and Unix credentials of the current process
353 *
354 * \param sock the socket file descriptor
355 * \param buf the buffer to be sent
356 *
357 * \return On success, this call returns the number of characters sent. On
358 * error, \p -E_SENDMSG ist returned.
359 * \sa okir's Black Hats Manual
360 * \sa sendmsg(2)
361 */
362 ssize_t send_cred_buffer(int sock, char *buf)
363 {
364 char control[sizeof(struct cmsghdr) + 10];
365 struct msghdr msg;
366 struct cmsghdr *cmsg;
367 static struct iovec iov;
368 struct ucred c;
369 int ret;
370
371 /* Response data */
372 iov.iov_base = buf;
373 iov.iov_len = strlen(buf);
374 c.pid = getpid();
375 c.uid = getuid();
376 c.gid = getgid();
377 /* compose the message */
378 memset(&msg, 0, sizeof(msg));
379 msg.msg_iov = &iov;
380 msg.msg_iovlen = 1;
381 msg.msg_control = control;
382 msg.msg_controllen = sizeof(control);
383 /* attach the ucred struct */
384 cmsg = CMSG_FIRSTHDR(&msg);
385 cmsg->cmsg_level = SOL_SOCKET;
386 cmsg->cmsg_type = SCM_CREDENTIALS;
387 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
388 *(struct ucred *)CMSG_DATA(cmsg) = c;
389 msg.msg_controllen = cmsg->cmsg_len;
390 ret = sendmsg(sock, &msg, 0);
391 if (ret < 0)
392 ret = -E_SENDMSG;
393 return ret;
394 }
395
396 static void dispose_fds(int *fds, int num)
397 {
398 int i;
399
400 for (i = 0; i < num; i++)
401 close(fds[i]);
402 }
403
404 /**
405 * receive a buffer and the Unix credentials of the sending process
406 *
407 * \param fd the socket file descriptor
408 * \param buf the buffer to store the message
409 * \param size the size of \a buffer
410 *
411 * \return negative on errors, the user id on success.
412 *
413 * \sa okir's Black Hats Manual
414 * \sa recvmsg(2)
415 */
416 int recv_cred_buffer(int fd, char *buf, size_t size)
417 {
418 char control[255];
419 struct msghdr msg;
420 struct cmsghdr *cmsg;
421 struct iovec iov;
422 int result = 0;
423 int yes = 1;
424 struct ucred cred;
425
426 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
427 memset(&msg, 0, sizeof(msg));
428 memset(buf, 0, size);
429 iov.iov_base = buf;
430 iov.iov_len = size;
431 msg.msg_iov = &iov;
432 msg.msg_iovlen = 1;
433 msg.msg_control = control;
434 msg.msg_controllen = sizeof(control);
435 if (recvmsg(fd, &msg, 0) < 0)
436 return -E_RECVMSG;
437 result = -E_SCM_CREDENTIALS;
438 cmsg = CMSG_FIRSTHDR(&msg);
439 while (cmsg) {
440 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
441 == SCM_CREDENTIALS) {
442 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
443 result = cred.uid;
444 } else
445 if (cmsg->cmsg_level == SOL_SOCKET
446 && cmsg->cmsg_type == SCM_RIGHTS) {
447 dispose_fds((int *) CMSG_DATA(cmsg),
448 (cmsg->cmsg_len - CMSG_LEN(0))
449 / sizeof(int));
450 }
451 cmsg = CMSG_NXTHDR(&msg, cmsg);
452 }
453 return result;
454 }
455 #endif /* HAVE_UCRED */
456
457 /** how many pending connections queue will hold */
458 #define BACKLOG 10
459
460 /**
461 * create a socket, bind it and listen
462 * \param port the tcp port to listen on
463 *
464 * \return The file descriptor of the created socket, negative
465 * on errors.
466 *
467 * \sa get_socket()
468 * \sa setsockopt(2)
469 * \sa bind(2)
470 * \sa listen(2)
471 */
472 int init_tcp_socket(int port)
473 {
474 int sockfd, ret;
475 struct sockaddr_in my_addr;
476
477 if ((sockfd = get_socket()) < 0)
478 return sockfd;
479 ret = setserversockopts(sockfd);
480 if (ret < 0)
481 return ret;
482 init_sockaddr(&my_addr, port, NULL);
483 ret = do_bind(sockfd, &my_addr);
484 if (ret < 0)
485 return ret;
486 if (listen(sockfd, BACKLOG) == -1)
487 return -E_LISTEN;
488 PARA_INFO_LOG("listening on port %d, fd %d\n", port, sockfd);
489 return sockfd;
490 }
491
492 /**
493 * receive a buffer and check for a pattern
494 *
495 * \param fd the file descriptor to receive from
496 * \param pattern the expected pattern
497 * \param bufsize the size of the internal buffer
498 *
499 * \return Positive if \a pattern was received, negative otherwise.
500 *
501 * This function creates a buffer of size \a bufsize and tries
502 * to receive at most \a bufsize bytes from file descriptor \a fd.
503 * If at least \p strlen(\a pattern) bytes were received, the beginning of
504 * the received buffer is compared with \a pattern, ignoring case.
505 * \sa recv_buffer()
506 * \sa strncasecmp(3)
507 */
508 int recv_pattern(int fd, const char *pattern, size_t bufsize)
509 {
510 size_t len = strlen(pattern);
511 char *buf = para_malloc(bufsize + 1);
512 int ret = -E_RECV_PATTERN, n = recv_buffer(fd, buf, bufsize);
513
514 if (n < len)
515 goto out;
516 if (strncasecmp(buf, pattern, len))
517 goto out;
518 ret = 1;
519 out:
520 if (ret < 0)
521 PARA_NOTICE_LOG("did not receive pattern '%s'\n", pattern);
522 free(buf);
523 return ret;
524 }