3 * $Id: check.c,v 1.3 1997/08/07 09:49:38 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 1.3 1997/08/07 09:49:38 mdw
33 * Extensive modifications to handle netgroups. Also sanitise user and group
34 * names before adding them to the symbol table.
36 * Revision 1.2 1997/08/04 10:24:20 mdw
37 * Sources placed under CVS control.
39 * Revision 1.1 1997/07/21 13:47:53 mdw
44 /*----- Header files ------------------------------------------------------*/
46 /* --- ANSI headers --- */
55 /* --- Unix headers --- */
58 #include <sys/types.h>
59 #include <sys/socket.h>
61 #include <netinet/in.h>
63 #include <arpa/inet.h>
68 /* --- Local headers --- */
83 /*----- Main code ---------------------------------------------------------*/
85 /* --- @check__send@ --- *
87 * Arguments: @unsigned char *crq@ = pointer to encrypted request
88 * @int fd@ = socket to send from
89 * @struct sockaddr_in *serv@ = pointer to table of servers
90 * @size_t n_serv@ = number of servers
94 * Use: Sends the request packet to the list of servers. If the
95 * message couldn't be sent to any of them, an error is
99 static void check__send(unsigned char *crq, int fd,
100 struct sockaddr_in *serv, size_t n_serv)
106 for (i = 0; i < n_serv; i++) {
107 if (sendto(fd, (char *)crq, crq_size, 0,
108 (struct sockaddr *)(serv + i), sizeof(serv[i])) < 0) {
109 T( trace(TRACE_CLIENT, "client: send to %s failed: %s",
110 inet_ntoa(serv[i].sin_addr), strerror(errno)); )
117 die("couldn't send request to server: %s", strerror(err));
120 /* --- @check__ask@ --- *
122 * Arguments: @request *rq@ = pointer to request buffer
123 * @struct sockaddr_in *serv@ = pointer to table of servers
124 * @size_t n_serv@ = number of servers
126 * Returns: Nonzero if OK, zero if forbidden
128 * Use: Contacts a number of servers to decide whether the request
132 static int check__ask(request *rq, struct sockaddr_in *serv, size_t n_serv)
135 unsigned char crq[crq_size];
136 unsigned char sk[IDEA_KEYSIZE];
140 /* --- First, build the encrypted request packet --- */
143 unsigned char k[IDEA_KEYSIZE];
146 /* --- Read in the encryption key --- */
148 if ((fp = fopen(file_KEY, "r")) == 0) {
149 die("couldn't open key file `%s': %s", file_KEY,
152 tx_getBits(k, 128, fp);
154 /* --- Now build a request packet --- */
158 crypt_packRequest(rq, crq, t, pid, k, sk);
160 T( trace(TRACE_CLIENT, "client: encrypted request packet"); )
163 /* --- Create my socket --- */
166 struct sockaddr_in sin;
168 if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
169 die("couldn't create socket: %s", strerror(errno));
171 /* --- Bind myself to some address --- */
173 sin.sin_family = AF_INET;
175 sin.sin_addr.s_addr = htonl(INADDR_ANY);
177 if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0)
178 die("couldn't bind socket to address: %s", strerror(errno));
181 /* --- Now wait for a reply --- */
185 struct timeval start, now, tv;
189 /* --- State table for waiting for replies --- *
191 * For each number, send off the request to our servers, and wait for
192 * that many seconds to have elapsed since we started. If the number is
193 * %$-1$% then it's time to give up.
196 static int tbl[] = { 0, 5, 10, 20, -1 };
198 /* --- Find out when we are --- */
200 gettimeofday(&start, 0);
203 /* --- Now loop until everything's done --- */
206 gettimeofday(&now, 0);
208 /* --- If the current timer has expired, find one that hasn't --- *
210 * Also resend the request after I've found a timer which is still
211 * extant. If there aren't any, report an error.
214 if (now.tv_sec >= start.tv_sec + tbl[ind] &&
215 now.tv_usec >= start.tv_usec) {
219 die("no reply from servers");
220 } while (now.tv_sec >= start.tv_sec + tbl[ind] &&
221 now.tv_usec >= start.tv_usec);
222 check__send(crq, fd, serv, n_serv);
223 T( trace(TRACE_CLIENT, "client: send request to servers"); )
226 /* --- Now wait for a packet to arrive --- */
228 if (now.tv_usec > start.tv_usec) {
229 now.tv_usec -= 1000000;
232 tv.tv_sec = start.tv_sec + tbl[ind] - now.tv_sec;
233 tv.tv_usec = start.tv_usec - now.tv_usec;
235 /* --- Sort out file descriptors to watch --- */
240 /* --- Wait for them --- */
242 i = select(FD_SETSIZE, &fds, 0, 0, &tv);
243 if (i == 0 || (i < 0 && errno == EINTR))
246 die("error waiting for reply: %s", strerror(errno));
248 /* --- A reply should be waiting now --- */
251 struct sockaddr_in sin;
252 int slen = sizeof(sin);
253 unsigned char buff[256];
256 /* --- Read the reply data --- */
258 if (recvfrom(fd, (char *)buff, sizeof(buff), 0,
259 (struct sockaddr *)&sin, &slen) < 0)
260 die("error reading server's reply: %s", strerror(errno));
262 IF_TRACING(TRACE_CLIENT, {
263 struct hostent *h = gethostbyaddr((char *)&sin.sin_addr,
264 sizeof(sin.sin_addr), AF_INET);
265 trace(TRACE_CLIENT, "client: reply received from %s port %i",
266 h ? h->h_name : inet_ntoa(sin.sin_addr),
267 ntohs(sin.sin_port));
270 /* --- Verify the sender --- *
272 * This is more to avoid confusion than for security: an active
273 * attacker is quite capable of forging the source address. We rely
274 * on the checksum in the reply packet for authentication.
277 for (i = 0; i < n_serv; i++) {
278 if (sin.sin_addr.s_addr == serv[i].sin_addr.s_addr &&
279 sin.sin_port == serv[i].sin_port)
283 T( trace(TRACE_CLIENT, "client: reply from unknown host"); )
287 /* --- Unpack and verify the response --- */
289 answer = crypt_unpackReply(buff, sk, t, pid);
291 T( trace(TRACE_CLIENT,
292 "client: invalid or corrupt reply packet"); )
300 die("internal error: can't get here in check__ask");
304 /* --- @check__client@ --- *
306 * Arguments: @request *rq@ = pointer to a request block
307 * @FILE *fp@ = file containing server configuration
309 * Returns: Nonzero if OK, zero if forbidden
311 * Use: Asks one or several servers whether a request is acceptable.
314 int check__client(request *rq, FILE *fp)
316 /* --- Format of the file --- *
318 * The `servers' file contains entries of the form
320 * %%\syntax{<host> [`:' <port>]}%%
322 * separates by whitespace. I build them all into an array of socket
323 * addresses and pass the whole lot to another function.
326 struct sockaddr_in *serv; /* Array of servers */
327 size_t n_serv, max_serv; /* Number and maximum number */
329 /* --- Initialise the server array --- */
331 T( trace(TRACE_CLIENT, "client: reading server definitions"); )
332 n_serv = 0; max_serv = 4; /* Four seems reasonable */
333 serv = xmalloc(sizeof(*serv) * max_serv);
335 /* --- Start reading the file --- */
338 char buff[256], *p, *l; /* A buffer and pointers for it */
339 int port; /* Default port for servers */
340 int state; /* Current parser state */
341 struct in_addr t_host; /* Temp place for an address*/
342 int t_port; /* Temp place for a port */
343 int ch; /* The current character */
345 /* --- Parser states --- */
348 st_start, /* Waiting to begin */
349 st_host, /* Reading a new hostname */
350 st_colon, /* Expecting a colon, maybe */
351 st_preport, /* Waiting before reading port */
352 st_port, /* Reading a port number */
353 st_commit, /* Commit a newly read server */
354 st_done /* Finished reading the file */
357 /* --- Find a default port --- */
360 struct servent *s = getservbyname(quis(), "udp");
361 port = (s ? s->s_port : -1);
364 /* --- Initialise for scanning the file --- */
368 l = buff + sizeof(buff);
372 /* --- Go for it --- */
374 while (state != st_done) {
377 /* --- Initial whitespace before hostname --- */
382 else if (isspace((unsigned char)ch))
388 /* --- Read a host name --- */
392 die("string too long in `" file_SERVER "'");
393 if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') {
400 if ((h = gethostbyname(buff)) == 0)
401 die("unknown host `%s' in `" file_SERVER "'", buff);
402 memcpy(&t_host, h->h_addr, sizeof(t_host));
407 /* --- Waiting for a colon coming up --- */
412 else if (isspace((unsigned char)ch))
414 else if (ch == ':') {
422 /* --- Clearing whitespace before a port number --- */
427 else if (isspace((unsigned char)ch))
435 /* --- Read a port number --- */
439 die("string too long in `" file_SERVER "'");
440 if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') {
447 s = getservbyname(buff, "udp");
448 if (!s && isdigit((unsigned char)buff[0]))
449 t_port = htons(atoi(buff));
451 die("unknown service `%s' in `" file_SERVER "'", buff);
458 /* --- A server has been read successfully --- */
461 if (n_serv == max_serv) {
463 serv = xrealloc(serv, max_serv * sizeof(*serv));
465 serv[n_serv].sin_family = AF_INET;
466 serv[n_serv].sin_addr = t_host;
467 serv[n_serv].sin_port = t_port;
474 /* --- A safety net for a broken parser --- */
477 die("internal error: can't get here in check__client");
485 /* --- Now start sending requests --- */
488 die("no servers specified in `" file_SERVER "'");
490 IF_TRACING(TRACE_CLIENT, {
493 for (i = 0; i < n_serv; i++) {
494 trace(TRACE_CLIENT, "client: server %s port %i",
495 inet_ntoa(serv[i].sin_addr), ntohs(serv[i].sin_port));
498 return (check__ask(rq, serv, n_serv));
503 * Arguments: @request *rq@ = pointer to request buffer
505 * Returns: Nonzero if OK, zero if forbidden
507 * Use: Checks to see if the request is acceptable.
510 int check(request *rq)
514 /* --- Check if we need to talk to a server --- */
516 if ((fp = fopen(file_SERVER, "r")) != 0)
517 return (check__client(rq, fp));
519 /* --- Otherwise do this all the old-fashioned way --- */
521 if ((fp = fopen(file_RULES, "r")) == 0) {
522 die("couldn't read configuration file `%s': %s",
523 file_RULES, strerror(errno));
535 return (rule_check(rq));
538 /*----- That's all, folks -------------------------------------------------*/