3 * $Id: check.c,v 1.2 1997/08/04 10:24:20 mdw Exp $
5 * Check validity of requests
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of `become'
14 * `Become' is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
19 * `Become' is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with `become'; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 /*----- Revision history --------------------------------------------------*
32 * Revision 1.2 1997/08/04 10:24:20 mdw
33 * Sources placed under CVS control.
35 * Revision 1.1 1997/07/21 13:47:53 mdw
40 /*----- Header files ------------------------------------------------------*/
42 /* --- ANSI headers --- */
51 /* --- Unix headers --- */
54 #include <sys/types.h>
55 #include <sys/socket.h>
57 #include <netinet/in.h>
59 #include <arpa/inet.h>
64 /* --- Local headers --- */
78 /*----- Main code ---------------------------------------------------------*/
80 /* --- @check__send@ --- *
82 * Arguments: @unsigned char *crq@ = pointer to encrypted request
83 * @int fd@ = socket to send from
84 * @struct sockaddr_in *serv@ = pointer to table of servers
85 * @size_t n_serv@ = number of servers
89 * Use: Sends the request packet to the list of servers. If the
90 * message couldn't be sent to any of them, an error is
94 static void check__send(unsigned char *crq, int fd,
95 struct sockaddr_in *serv, size_t n_serv)
101 for (i = 0; i < n_serv; i++) {
102 if (sendto(fd, (char *)crq, crq_size, 0,
103 (struct sockaddr *)(serv + i), sizeof(serv[i])) < 0) {
104 T( trace(TRACE_CLIENT, "client: send to %s failed: %s",
105 inet_ntoa(serv[i].sin_addr), strerror(errno)); )
112 die("couldn't send request to server: %s", strerror(err));
115 /* --- @check__ask@ --- *
117 * Arguments: @request *rq@ = pointer to request buffer
118 * @struct sockaddr_in *serv@ = pointer to table of servers
119 * @size_t n_serv@ = number of servers
121 * Returns: Nonzero if OK, zero if forbidden
123 * Use: Contacts a number of servers to decide whether the request
127 static int check__ask(request *rq, struct sockaddr_in *serv, size_t n_serv)
130 unsigned char crq[crq_size];
131 unsigned char sk[IDEA_KEYSIZE];
135 /* --- First, build the encrypted request packet --- */
138 unsigned char k[IDEA_KEYSIZE];
141 /* --- Read in the encryption key --- */
143 if ((fp = fopen(file_KEY, "r")) == 0) {
144 die("couldn't open key file `%s': %s", file_KEY,
147 tx_getBits(k, 128, fp);
149 /* --- Now build a request packet --- */
153 crypt_packRequest(rq, crq, t, pid, k, sk);
155 T( trace(TRACE_CLIENT, "client: encrypted request packet"); )
158 /* --- Create my socket --- */
161 struct sockaddr_in sin;
163 if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
164 die("couldn't create socket: %s", strerror(errno));
166 /* --- Bind myself to some address --- */
168 sin.sin_family = AF_INET;
170 sin.sin_addr.s_addr = htonl(INADDR_ANY);
172 if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0)
173 die("couldn't bind socket to address: %s", strerror(errno));
176 /* --- Now wait for a reply --- */
180 struct timeval start, now, tv;
184 /* --- State table for waiting for replies --- *
186 * For each number, send off the request to our servers, and wait for
187 * that many seconds to have elapsed since we started. If the number is
188 * %$-1$% then it's time to give up.
191 static int tbl[] = { 0, 5, 10, 20, -1 };
193 /* --- Find out when we are --- */
195 gettimeofday(&start, 0);
198 /* --- Now loop until everything's done --- */
201 gettimeofday(&now, 0);
203 /* --- If the current timer has expired, find one that hasn't --- *
205 * Also resend the request after I've found a timer which is still
206 * extant. If there aren't any, report an error.
209 if (now.tv_sec >= start.tv_sec + tbl[ind] &&
210 now.tv_usec >= start.tv_usec) {
214 die("no reply from servers");
215 } while (now.tv_sec >= start.tv_sec + tbl[ind] &&
216 now.tv_usec >= start.tv_usec);
217 check__send(crq, fd, serv, n_serv);
218 T( trace(TRACE_CLIENT, "client: send request to servers"); )
221 /* --- Now wait for a packet to arrive --- */
223 if (now.tv_usec > start.tv_usec) {
224 now.tv_usec -= 1000000;
227 tv.tv_sec = start.tv_sec + tbl[ind] - now.tv_sec;
228 tv.tv_usec = start.tv_usec - now.tv_usec;
230 /* --- Sort out file descriptors to watch --- */
235 /* --- Wait for them --- */
237 i = select(FD_SETSIZE, &fds, 0, 0, &tv);
238 if (i == 0 || (i < 0 && errno == EINTR))
241 die("error waiting for reply: %s", strerror(errno));
243 /* --- A reply should be waiting now --- */
246 struct sockaddr_in sin;
247 int slen = sizeof(sin);
248 unsigned char buff[256];
251 /* --- Read the reply data --- */
253 if (recvfrom(fd, (char *)buff, sizeof(buff), 0,
254 (struct sockaddr *)&sin, &slen) < 0)
255 die("error reading server's reply: %s", strerror(errno));
257 IF_TRACING(TRACE_CLIENT, {
258 struct hostent *h = gethostbyaddr((char *)&sin.sin_addr,
259 sizeof(sin.sin_addr), AF_INET);
260 trace(TRACE_CLIENT, "client: reply received from %s port %i",
261 h ? h->h_name : inet_ntoa(sin.sin_addr),
262 ntohs(sin.sin_port));
265 /* --- Verify the sender --- *
267 * This is more to avoid confusion than for security: an active
268 * attacker is quite capable of forging the source address. We rely
269 * on the checksum in the reply packet for authentication.
272 for (i = 0; i < n_serv; i++) {
273 if (sin.sin_addr.s_addr == serv[i].sin_addr.s_addr &&
274 sin.sin_port == serv[i].sin_port)
278 T( trace(TRACE_CLIENT, "client: reply from unknown host"); )
282 /* --- Unpack and verify the response --- */
284 answer = crypt_unpackReply(buff, sk, t, pid);
286 T( trace(TRACE_CLIENT,
287 "client: invalid or corrupt reply packet"); )
295 die("internal error: can't get here in check__ask");
299 /* --- @check__client@ --- *
301 * Arguments: @request *rq@ = pointer to a request block
302 * @FILE *fp@ = file containing server configuration
304 * Returns: Nonzero if OK, zero if forbidden
306 * Use: Asks one or several servers whether a request is acceptable.
309 int check__client(request *rq, FILE *fp)
311 /* --- Format of the file --- *
313 * The `servers' file contains entries of the form
315 * %%\syntax{<host> [`:' <port>]}%%
317 * separates by whitespace. I build them all into an array of socket
318 * addresses and pass the whole lot to another function.
321 struct sockaddr_in *serv; /* Array of servers */
322 size_t n_serv, max_serv; /* Number and maximum number */
324 /* --- Initialise the server array --- */
326 T( trace(TRACE_CLIENT, "client: reading server definitions"); )
327 n_serv = 0; max_serv = 4; /* Four seems reasonable */
328 serv = xmalloc(sizeof(*serv) * max_serv);
330 /* --- Start reading the file --- */
333 char buff[256], *p, *l; /* A buffer and pointers for it */
334 int port; /* Default port for servers */
335 int state; /* Current parser state */
336 struct in_addr t_host; /* Temp place for an address*/
337 int t_port; /* Temp place for a port */
338 int ch; /* The current character */
340 /* --- Parser states --- */
343 st_start, /* Waiting to begin */
344 st_host, /* Reading a new hostname */
345 st_colon, /* Expecting a colon, maybe */
346 st_preport, /* Waiting before reading port */
347 st_port, /* Reading a port number */
348 st_commit, /* Commit a newly read server */
349 st_done /* Finished reading the file */
352 /* --- Find a default port --- */
355 struct servent *s = getservbyname(quis(), "udp");
356 port = (s ? s->s_port : -1);
359 /* --- Initialise for scanning the file --- */
363 l = buff + sizeof(buff);
367 /* --- Go for it --- */
369 while (state != st_done) {
372 /* --- Initial whitespace before hostname --- */
377 else if (isspace((unsigned char)ch))
383 /* --- Read a host name --- */
387 die("string too long in `" file_SERVER "'");
388 if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') {
395 if ((h = gethostbyname(buff)) == 0)
396 die("unknown host `%s' in `" file_SERVER "'", buff);
397 memcpy(&t_host, h->h_addr, sizeof(t_host));
402 /* --- Waiting for a colon coming up --- */
407 else if (isspace((unsigned char)ch))
409 else if (ch == ':') {
417 /* --- Clearing whitespace before a port number --- */
422 else if (isspace((unsigned char)ch))
430 /* --- Read a port number --- */
434 die("string too long in `" file_SERVER "'");
435 if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') {
442 s = getservbyname(buff, "udp");
443 if (!s && isdigit((unsigned char)buff[0]))
444 t_port = htons(atoi(buff));
446 die("unknown service `%s' in `" file_SERVER "'", buff);
453 /* --- A server has been read successfully --- */
456 if (n_serv == max_serv) {
458 serv = xrealloc(serv, max_serv * sizeof(*serv));
460 serv[n_serv].sin_family = AF_INET;
461 serv[n_serv].sin_addr = t_host;
462 serv[n_serv].sin_port = t_port;
469 /* --- A safety net for a broken parser --- */
472 die("internal error: can't get here in check__client");
480 /* --- Now start sending requests --- */
483 die("no servers specified in `" file_SERVER "'");
485 IF_TRACING(TRACE_CLIENT, {
488 for (i = 0; i < n_serv; i++) {
489 trace(TRACE_CLIENT, "client: server %s port %i",
490 inet_ntoa(serv[i].sin_addr), ntohs(serv[i].sin_port));
493 return (check__ask(rq, serv, n_serv));
498 * Arguments: @request *rq@ = pointer to request buffer
500 * Returns: Nonzero if OK, zero if forbidden
502 * Use: Checks to see if the request is acceptable.
505 int check(request *rq)
509 /* --- Check if we need to talk to a server --- */
511 if ((fp = fopen(file_SERVER, "r")) != 0)
512 return (check__client(rq, fp));
514 /* --- Otherwise do this all the old-fashioned way --- */
516 if ((fp = fopen(file_RULES, "r")) == 0) {
517 die("couldn't read configuration file `%s': %s",
518 file_RULES, strerror(errno));
529 return (rule_check(rq));
532 /*----- That's all, folks -------------------------------------------------*/