3 * $Id: check.c,v 1.6 1998/01/12 16:45:47 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 1.6 1998/01/12 16:45:47 mdw
35 * Revision 1.5 1997/09/26 09:14:58 mdw
36 * Merged blowfish branch into trunk.
38 * Revision 1.4.2.1 1997/09/26 09:08:01 mdw
39 * Use the Blowfish encryption algorithm instead of IDEA. This is partly
40 * because I prefer Blowfish (without any particularly strong evidence) but
41 * mainly because IDEA is patented and Blowfish isn't.
43 * Revision 1.4 1997/08/07 09:52:05 mdw
44 * (Log entry for previous version is bogus.) Added support for multiple
47 * Revision 1.2 1997/08/04 10:24:20 mdw
48 * Sources placed under CVS control.
50 * Revision 1.1 1997/07/21 13:47:53 mdw
55 /*----- Header files ------------------------------------------------------*/
57 /* --- ANSI headers --- */
66 /* --- Unix headers --- */
69 #include <sys/types.h>
70 #include <sys/socket.h>
72 #include <netinet/in.h>
74 #include <arpa/inet.h>
79 /* --- Local headers --- */
94 /*----- Main code ---------------------------------------------------------*/
96 /* --- @check__send@ --- *
98 * Arguments: @unsigned char *crq@ = pointer to encrypted request
99 * @int fd@ = socket to send from
100 * @struct sockaddr_in *serv@ = pointer to table of servers
101 * @size_t n_serv@ = number of servers
105 * Use: Sends the request packet to the list of servers. If the
106 * message couldn't be sent to any of them, an error is
110 static void check__send(unsigned char *crq
, int fd
,
111 struct sockaddr_in
*serv
, size_t n_serv
)
117 for (i
= 0; i
< n_serv
; i
++) {
118 if (sendto(fd
, (char *)crq
, crq_size
, 0,
119 (struct sockaddr
*)(serv
+ i
), sizeof(serv
[i
])) < 0) {
120 T( trace(TRACE_CLIENT
, "client: send to %s failed: %s",
121 inet_ntoa(serv
[i
].sin_addr
), strerror(errno
)); )
128 die("couldn't send request to server: %s", strerror(err
));
131 /* --- @check__ask@ --- *
133 * Arguments: @request *rq@ = pointer to request buffer
134 * @struct sockaddr_in *serv@ = pointer to table of servers
135 * @size_t n_serv@ = number of servers
137 * Returns: Nonzero if OK, zero if forbidden
139 * Use: Contacts a number of servers to decide whether the request
143 static int check__ask(request
*rq
, struct sockaddr_in
*serv
, size_t n_serv
)
146 unsigned char crq
[crq_size
];
147 unsigned char sk
[BLOWFISH_KEYSIZE
];
151 /* --- First, build the encrypted request packet --- */
154 unsigned char k
[BLOWFISH_KEYSIZE
];
157 /* --- Read in the encryption key --- */
159 if ((fp
= fopen(file_KEY
, "r")) == 0) {
160 die("couldn't open key file `%s': %s", file_KEY
,
163 tx_getBits(k
, 128, fp
);
165 /* --- Now build a request packet --- */
169 crypt_packRequest(rq
, crq
, t
, pid
, k
, sk
);
171 T( trace(TRACE_CLIENT
, "client: encrypted request packet"); )
174 /* --- Create my socket --- */
177 struct sockaddr_in sin
;
179 if ((fd
= socket(PF_INET
, SOCK_DGRAM
, 0)) < 0)
180 die("couldn't create socket: %s", strerror(errno
));
182 /* --- Bind myself to some address --- */
184 sin
.sin_family
= AF_INET
;
186 sin
.sin_addr
.s_addr
= htonl(INADDR_ANY
);
188 if (bind(fd
, (struct sockaddr
*)&sin
, sizeof(sin
)) < 0)
189 die("couldn't bind socket to address: %s", strerror(errno
));
192 /* --- Now wait for a reply --- */
196 struct timeval start
, now
, tv
;
200 /* --- State table for waiting for replies --- *
202 * For each number, send off the request to our servers, and wait for
203 * that many seconds to have elapsed since we started. If the number is
204 * %$-1$% then it's time to give up.
207 static int tbl
[] = { 0, 5, 10, 20, -1 };
209 /* --- Find out when we are --- */
211 gettimeofday(&start
, 0);
214 /* --- Now loop until everything's done --- */
217 gettimeofday(&now
, 0);
219 /* --- If the current timer has expired, find one that hasn't --- *
221 * Also resend the request after I've found a timer which is still
222 * extant. If there aren't any, report an error.
225 if (now
.tv_sec
>= start
.tv_sec
+ tbl
[ind
] &&
226 now
.tv_usec
>= start
.tv_usec
) {
230 die("no reply from servers");
231 } while (now
.tv_sec
>= start
.tv_sec
+ tbl
[ind
] &&
232 now
.tv_usec
>= start
.tv_usec
);
233 check__send(crq
, fd
, serv
, n_serv
);
234 T( trace(TRACE_CLIENT
, "client: send request to servers"); )
237 /* --- Now wait for a packet to arrive --- */
239 if (now
.tv_usec
> start
.tv_usec
) {
240 now
.tv_usec
-= 1000000;
243 tv
.tv_sec
= start
.tv_sec
+ tbl
[ind
] - now
.tv_sec
;
244 tv
.tv_usec
= start
.tv_usec
- now
.tv_usec
;
246 /* --- Sort out file descriptors to watch --- */
251 /* --- Wait for them --- */
253 i
= select(FD_SETSIZE
, &fds
, 0, 0, &tv
);
254 if (i
== 0 || (i
< 0 && errno
== EINTR
))
257 die("error waiting for reply: %s", strerror(errno
));
259 /* --- A reply should be waiting now --- */
262 struct sockaddr_in sin
;
263 int slen
= sizeof(sin
);
264 unsigned char buff
[256];
267 /* --- Read the reply data --- */
269 if (recvfrom(fd
, (char *)buff
, sizeof(buff
), 0,
270 (struct sockaddr
*)&sin
, &slen
) < 0)
271 die("error reading server's reply: %s", strerror(errno
));
273 IF_TRACING(TRACE_CLIENT
, {
274 struct hostent
*h
= gethostbyaddr((char *)&sin
.sin_addr
,
275 sizeof(sin
.sin_addr
), AF_INET
);
276 trace(TRACE_CLIENT
, "client: reply received from %s port %i",
277 h ? h
->h_name
: inet_ntoa(sin
.sin_addr
),
278 ntohs(sin
.sin_port
));
281 /* --- Verify the sender --- *
283 * This is more to avoid confusion than for security: an active
284 * attacker is quite capable of forging the source address. We rely
285 * on the checksum in the reply packet for authentication.
288 for (i
= 0; i
< n_serv
; i
++) {
289 if (sin
.sin_addr
.s_addr
== serv
[i
].sin_addr
.s_addr
&&
290 sin
.sin_port
== serv
[i
].sin_port
)
294 T( trace(TRACE_CLIENT
, "client: reply from unknown host"); )
298 /* --- Unpack and verify the response --- */
300 answer
= crypt_unpackReply(buff
, sk
, t
, pid
);
302 T( trace(TRACE_CLIENT
,
303 "client: invalid or corrupt reply packet"); )
311 die("internal error: can't get here in check__ask");
315 /* --- @check__client@ --- *
317 * Arguments: @request *rq@ = pointer to a request block
318 * @FILE *fp@ = file containing server configuration
320 * Returns: Nonzero if OK, zero if forbidden
322 * Use: Asks one or several servers whether a request is acceptable.
325 int check__client(request
*rq
, FILE *fp
)
327 /* --- Format of the file --- *
329 * The `servers' file contains entries of the form
331 * %%\syntax{<host> [`:' <port>]}%%
333 * separates by whitespace. I build them all into an array of socket
334 * addresses and pass the whole lot to another function.
337 struct sockaddr_in
*serv
; /* Array of servers */
338 size_t n_serv
, max_serv
; /* Number and maximum number */
340 /* --- Initialise the server array --- */
342 T( trace(TRACE_CLIENT
, "client: reading server definitions"); )
343 n_serv
= 0; max_serv
= 4; /* Four seems reasonable */
344 serv
= xmalloc(sizeof(*serv
) * max_serv
);
346 /* --- Start reading the file --- */
349 char buff
[256], *p
, *l
; /* A buffer and pointers for it */
350 int port
; /* Default port for servers */
351 int state
; /* Current parser state */
352 struct in_addr t_host
; /* Temp place for an address*/
353 int t_port
; /* Temp place for a port */
354 int ch
; /* The current character */
356 /* --- Parser states --- */
359 st_start
, /* Waiting to begin */
360 st_host
, /* Reading a new hostname */
361 st_colon
, /* Expecting a colon, maybe */
362 st_preport
, /* Waiting before reading port */
363 st_port
, /* Reading a port number */
364 st_commit
, /* Commit a newly read server */
365 st_done
/* Finished reading the file */
368 /* --- Find a default port --- */
371 struct servent
*s
= getservbyname(quis(), "udp");
372 port
= (s ? s
->s_port
: -1);
375 /* --- Initialise for scanning the file --- */
379 l
= buff
+ sizeof(buff
);
383 /* --- Go for it --- */
385 while (state
!= st_done
) {
388 /* --- Initial whitespace before hostname --- */
393 else if (isspace((unsigned char)ch
))
399 /* --- Read a host name --- */
403 die("string too long in `" file_SERVER
"'");
404 if (ch
!= EOF
&& !isspace((unsigned char)ch
) && ch
!= ':') {
411 if ((h
= gethostbyname(buff
)) == 0)
412 die("unknown host `%s' in `" file_SERVER
"'", buff
);
413 memcpy(&t_host
, h
->h_addr
, sizeof(t_host
));
418 /* --- Waiting for a colon coming up --- */
423 else if (isspace((unsigned char)ch
))
425 else if (ch
== ':') {
433 /* --- Clearing whitespace before a port number --- */
438 else if (isspace((unsigned char)ch
))
446 /* --- Read a port number --- */
450 die("string too long in `" file_SERVER
"'");
451 if (ch
!= EOF
&& !isspace((unsigned char)ch
) && ch
!= ':') {
458 s
= getservbyname(buff
, "udp");
459 if (!s
&& isdigit((unsigned char)buff
[0]))
460 t_port
= htons(atoi(buff
));
462 die("unknown service `%s' in `" file_SERVER
"'", buff
);
469 /* --- A server has been read successfully --- */
472 if (n_serv
== max_serv
) {
474 serv
= xrealloc(serv
, max_serv
* sizeof(*serv
));
476 serv
[n_serv
].sin_family
= AF_INET
;
477 serv
[n_serv
].sin_addr
= t_host
;
478 serv
[n_serv
].sin_port
= t_port
;
485 /* --- A safety net for a broken parser --- */
488 die("internal error: can't get here in check__client");
496 /* --- Now start sending requests --- */
499 die("no servers specified in `" file_SERVER
"'");
501 IF_TRACING(TRACE_CLIENT
, {
504 for (i
= 0; i
< n_serv
; i
++) {
505 trace(TRACE_CLIENT
, "client: server %s port %i",
506 inet_ntoa(serv
[i
].sin_addr
), ntohs(serv
[i
].sin_port
));
509 return (check__ask(rq
, serv
, n_serv
));
514 * Arguments: @request *rq@ = pointer to request buffer
516 * Returns: Nonzero if OK, zero if forbidden
518 * Use: Checks to see if the request is acceptable.
521 int check(request
*rq
)
525 /* --- Check if we need to talk to a server --- */
527 if ((fp
= fopen(file_SERVER
, "r")) != 0)
528 return (check__client(rq
, fp
));
530 /* --- Otherwise do this all the old-fashioned way --- */
532 if ((fp
= fopen(file_RULES
, "r")) == 0) {
533 die("couldn't read configuration file `%s': %s",
534 file_RULES
, strerror(errno
));
546 return (rule_check(rq
));
549 /*----- That's all, folks -------------------------------------------------*/