Commit | Line | Data |
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a759efa6 | 1 | /* -*-c-*- |
a759efa6 | 2 | * |
3 | * Background reverse name resolution | |
4 | * | |
5 | * (c) 1999 Straylight/Edgeware | |
6 | */ | |
7 | ||
d4efbcd9 | 8 | /*----- Licensing notice --------------------------------------------------* |
a759efa6 | 9 | * |
10 | * This file is part of the mLib utilities library. | |
11 | * | |
12 | * mLib is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU Library General Public License as | |
14 | * published by the Free Software Foundation; either version 2 of the | |
15 | * License, or (at your option) any later version. | |
d4efbcd9 | 16 | * |
a759efa6 | 17 | * mLib is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU Library General Public License for more details. | |
d4efbcd9 | 21 | * |
a759efa6 | 22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with mLib; if not, write to the Free | |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
25 | * MA 02111-1307, USA. | |
26 | */ | |
27 | ||
a759efa6 | 28 | /*----- Header files ------------------------------------------------------*/ |
29 | ||
a0150d8d MW |
30 | #include "config.h" |
31 | ||
a759efa6 | 32 | #include <errno.h> |
33 | #include <signal.h> | |
34 | #include <stdio.h> | |
35 | #include <stdlib.h> | |
36 | #include <string.h> | |
37 | ||
38 | #include <sys/types.h> | |
39 | #include <sys/time.h> | |
40 | #include <unistd.h> | |
41 | #include <sys/wait.h> | |
42 | ||
43 | #include <sys/socket.h> | |
44 | #include <netinet/in.h> | |
45 | #include <arpa/inet.h> | |
46 | #include <netdb.h> | |
47 | ||
6c3a7cf7 | 48 | #include "alloc.h" |
a759efa6 | 49 | #include "bres.h" |
ff1e93ac | 50 | #include "mdup.h" |
6c3a7cf7 | 51 | #include "report.h" |
52 | #include "sel.h" | |
a759efa6 | 53 | |
54 | /*----- Magic numbers -----------------------------------------------------*/ | |
55 | ||
56 | #define BRES_MAX 15 /* Maximum number of resolvers */ | |
57 | #define BRES_IDLE 60 /* Lifetime of an idle resolver */ | |
58 | ||
59 | /*----- Static variables --------------------------------------------------*/ | |
60 | ||
61 | #ifndef BRES_STANDALONE | |
62 | ||
63 | static bres_server servers[BRES_MAX]; /* Statically allocated servers */ | |
64 | ||
ffb41122 MW |
65 | static bres_server *freelist, *freetail; |
66 | static bres_client *qhead, *qtail; | |
67 | static sel_state *sel; | |
68 | static const char *server = 0; | |
a759efa6 | 69 | |
ffb41122 MW |
70 | #define UNLINK(head, tail, p) do { \ |
71 | *((p)->next ? &(p)->next->prev : &(tail)) = (p)->prev; \ | |
72 | *((p)->prev ? &(p)->prev->next : &(head)) = (p)->next; \ | |
73 | } while (0) | |
a759efa6 | 74 | |
ffb41122 MW |
75 | #define LINKHEAD(head, tail, p) do { \ |
76 | (p)->next = (head); \ | |
77 | (p)->prev = 0; \ | |
78 | *((head) ? &(head)->prev : &(tail)) = (p); \ | |
79 | (head) = (p); \ | |
80 | } while (0) | |
a759efa6 | 81 | |
ffb41122 MW |
82 | #define LINKTAIL(head, tail, p) do { \ |
83 | (p)->next = 0; \ | |
84 | (p)->prev = (head); \ | |
85 | *((tail) ? &(tail)->next : &(head)) = (p); \ | |
86 | (tail) = (p); \ | |
87 | } while (0) | |
a759efa6 | 88 | |
89 | #endif | |
90 | ||
91 | /*----- Background resolver protocol --------------------------------------*/ | |
92 | ||
93 | /* --- Requests and responses --- * | |
94 | * | |
95 | * There are two types of requests: name and addr, corresponding to the | |
96 | * standard @gethostbyname@ and @gethostbyaddr@ calls. There are two types | |
97 | * of responses too: a positive response consists of an encoded equivalent of | |
98 | * a @struct hostent@ structure containing the requested information; a | |
99 | * negative response consists of an @h_errno@ value explaining the problem. | |
100 | */ | |
101 | ||
102 | #define BRES_BYNAME 0 /* Request: resolve given name */ | |
103 | #define BRES_BYADDR 1 /* Request: resolve given address */ | |
104 | ||
105 | #define BRES_HOSTENT 0 /* Response: resolved ok */ | |
106 | #define BRES_ERROR 1 /* Response: resolution failed */ | |
107 | ||
108 | /* --- Encodings --- * | |
109 | * | |
110 | * A string is encoded as a @size_t@ length followed by the actual data. The | |
111 | * null terminator is not transmitted. | |
112 | * | |
113 | * Addresses for resolution are transmitted as raw @struct in_addr@ | |
114 | * structures. | |
115 | * | |
116 | * A @hostent@ structure is transmitted as a header containing fixed-size | |
117 | * information, followed by the official name, an array of aliases, and an | |
118 | * array of addresses. The number of items in the arrays is specified in the | |
119 | * header. | |
120 | * | |
121 | * The implementation assumes that a complete request or reply is always | |
122 | * sent. Undesirable blocking will occur if this is not the case. Both ends | |
123 | * are assumed to trust each other. A protocol failure results in the child | |
124 | * in question being terminated. | |
125 | */ | |
126 | ||
127 | typedef struct hostskel { | |
128 | size_t nalias; | |
129 | int addrtype; | |
130 | size_t addrsz; | |
131 | size_t naddr; | |
132 | } hostskel; | |
133 | ||
134 | /* --- @doread@, @dowrite@ --- * | |
135 | * | |
136 | * Arguments: @int fd@ = file descriptor | |
137 | * @void *buf@ = buffer for data | |
138 | * @size_t sz@ = size of data | |
139 | * | |
140 | * Returns: Zero if successful, nonzero otherwise. | |
141 | * | |
142 | * Use: Reads or writes a chunk of data. @EINTR@ errors are retried; | |
143 | * incomplete reads and writes are continued from where they | |
144 | * left off. End-of-file is considered an I/O error. | |
145 | */ | |
146 | ||
147 | static int doread(int fd, void *buf, size_t sz) | |
148 | { | |
149 | char *p = buf; | |
150 | while (sz) { | |
151 | int r = read(fd, p, sz); | |
152 | if (r < 0) { | |
153 | if (errno == EINTR) | |
154 | continue; | |
155 | return (-1); | |
156 | } else if (r == 0) { | |
157 | errno = EIO; | |
158 | return (-1); | |
159 | } | |
160 | sz -= r; | |
161 | p += r; | |
162 | } | |
163 | return (0); | |
164 | } | |
165 | ||
166 | static int dowrite(int fd, const void *buf, size_t sz) | |
167 | { | |
168 | const char *p = buf; | |
169 | while (sz) { | |
170 | int r = write(fd, p, sz); | |
171 | if (r < 0) { | |
172 | if (errno == EINTR) | |
173 | continue; | |
174 | return (-1); | |
175 | } else if (r == 0) { | |
176 | errno = EIO; | |
177 | return (-1); | |
178 | } | |
179 | sz -= r; | |
180 | p += r; | |
181 | } | |
182 | return (0); | |
183 | } | |
184 | ||
185 | /* --- @getstring@ --- * | |
186 | * | |
187 | * Arguments: @int fd@ = file descriptor to read | |
188 | * | |
189 | * Returns: String in heap-allocated block, or a null pointer. | |
190 | * | |
191 | * Use: Decodes a string. | |
192 | */ | |
193 | ||
194 | static char *getstring(int fd) | |
195 | { | |
196 | size_t sz; | |
197 | char *p; | |
198 | ||
199 | if (doread(fd, &sz, sizeof(sz)) || (p = malloc(sz + 1)) == 0) | |
200 | return (0); | |
201 | if (doread(fd, p, sz)) { | |
202 | free(p); | |
203 | return (0); | |
204 | } | |
205 | p[sz] = 0; | |
206 | return (p); | |
207 | } | |
208 | ||
209 | /* --- @putstring@ --- * | |
210 | * | |
211 | * Arguments: @int fd@ = file descriptor to write on | |
212 | * @const char *p@ = pointer to string to write | |
213 | * | |
214 | * Returns: Zero if successful. | |
215 | * | |
216 | * Use: Encodes a string. | |
217 | */ | |
218 | ||
219 | static int putstring(int fd, const char *p) | |
220 | { | |
221 | size_t sz = strlen(p); | |
222 | if (dowrite(fd, &sz, sizeof(sz)) || dowrite(fd, p, sz)) | |
223 | return (-1); | |
224 | return (0); | |
225 | } | |
226 | ||
227 | /* --- @gethost@ --- * | |
228 | * | |
229 | * Arguments: @int fd@ = file descriptor to read | |
230 | * | |
231 | * Returns: Pointer to heap-allocated @struct hostent@, or null. | |
232 | * | |
233 | * Use: Decodes a host structure. The resulting structure is all in | |
234 | * one big heap block. | |
235 | */ | |
236 | ||
237 | #ifndef BRES_STANDALONE | |
238 | ||
239 | static struct hostent *gethost(int fd) | |
240 | { | |
241 | hostskel hsk; | |
242 | struct hostent *h; | |
243 | char *name; | |
244 | char **alias = 0; | |
d4efbcd9 | 245 | |
a759efa6 | 246 | /* --- Read the skeleton structure --- */ |
247 | ||
248 | if (doread(fd, &hsk, sizeof(hsk))) | |
249 | goto tidy_0; | |
250 | ||
251 | /* --- Read the hostname and alias strings --- * | |
252 | * | |
253 | * Count the length of the strings as we go. | |
254 | */ | |
255 | ||
256 | { | |
257 | size_t sz = | |
258 | sizeof(struct hostent) + | |
259 | hsk.naddr * hsk.addrsz + | |
260 | (hsk.naddr + hsk.nalias + 2) * sizeof(char *); | |
261 | ||
262 | /* --- Read the primary host name --- */ | |
263 | ||
264 | if ((name = getstring(fd)) == 0) | |
265 | goto tidy_0; | |
266 | sz += strlen(name) + 1; | |
267 | ||
268 | /* --- Read in the alias names --- */ | |
269 | ||
270 | if (hsk.nalias) { | |
271 | int i; | |
272 | if ((alias = malloc(hsk.nalias * sizeof(char *))) == 0) | |
d4efbcd9 | 273 | goto tidy_1; |
a759efa6 | 274 | for (i = 0; i < hsk.nalias; i++) |
275 | alias[i] = 0; | |
276 | for (i = 0; i < hsk.nalias; i++) { | |
277 | if ((alias[i] = getstring(fd)) == 0) | |
278 | goto tidy_2; | |
279 | sz += strlen(alias[i]) + 1; | |
280 | } | |
281 | } | |
282 | ||
283 | /* --- Allocate the output structure --- */ | |
284 | ||
285 | if ((h = malloc(sz)) == 0) | |
286 | goto tidy_2; | |
287 | } | |
288 | ||
289 | /* --- Fill in the base structure --- */ | |
290 | ||
291 | h->h_addrtype = hsk.addrtype; | |
292 | h->h_length = hsk.addrsz; | |
293 | ||
294 | /* --- Start putting everything else in --- */ | |
295 | ||
296 | { | |
297 | char **p = (char **)(h + 1); | |
298 | char *a = (char *)(p + hsk.nalias + hsk.naddr + 2); | |
299 | int i; | |
300 | ||
301 | /* --- Start with the address table --- */ | |
302 | ||
303 | h->h_addr_list = p; | |
304 | if (doread(fd, a, hsk.naddr * hsk.addrsz)) | |
305 | goto tidy_2; | |
306 | for (i = 0; i < hsk.naddr; i++) { | |
a759efa6 | 307 | *p++ = a; |
364308dc | 308 | a += hsk.addrsz; |
a759efa6 | 309 | } |
310 | *p++ = 0; | |
311 | ||
312 | /* --- Finally copy the strings over --- */ | |
313 | ||
314 | #define PUT(_p) do { \ | |
315 | size_t _len = strlen(_p) + 1; \ | |
316 | memcpy(a, (_p), _len); \ | |
317 | a += _len; \ | |
318 | } while (0) | |
319 | ||
320 | h->h_name = a; | |
321 | PUT(name); | |
d8fe3fc2 | 322 | free(name); |
a759efa6 | 323 | h->h_aliases = p; |
324 | for (i = 0; i < hsk.nalias; i++) { | |
325 | *p++ = a; | |
326 | PUT(alias[i]); | |
d8fe3fc2 | 327 | free(alias[i]); |
a759efa6 | 328 | } |
329 | *p++ = 0; | |
d8fe3fc2 | 330 | free(alias); |
d4efbcd9 | 331 | |
a759efa6 | 332 | #undef PUT |
333 | } | |
334 | ||
335 | return (h); | |
336 | ||
337 | /* --- Tidy up after various types of failure --- */ | |
338 | ||
339 | tidy_2: | |
340 | { | |
341 | int i; | |
342 | for (i = 0; i < hsk.nalias && alias[i]; i++) | |
d8fe3fc2 | 343 | free(alias[i]); |
344 | free(alias); | |
a759efa6 | 345 | } |
346 | tidy_1: | |
d8fe3fc2 | 347 | free(name); |
a759efa6 | 348 | tidy_0: |
349 | return (0); | |
350 | } | |
351 | ||
352 | #endif | |
353 | ||
354 | /* --- @puthost@ --- * | |
355 | * | |
356 | * Arguments: @int fd@ = file descriptor | |
357 | * @struct hostent *h@ = pointer to host structure | |
358 | * | |
359 | * Returns: Zero if successful. | |
360 | * | |
361 | * Use: Encodes a host structure. | |
362 | */ | |
363 | ||
364 | static int puthost(int fd, struct hostent *h) | |
365 | { | |
366 | hostskel hsk; | |
367 | int i; | |
368 | ||
369 | /* --- Fill in and send the skeleton structure --- */ | |
370 | ||
371 | for (i = 0; h->h_aliases[i]; i++) | |
372 | ; | |
373 | hsk.nalias = i; | |
374 | for (i = 0; h->h_addr_list[i]; i++) | |
375 | ; | |
376 | hsk.naddr = i; | |
377 | hsk.addrtype = h->h_addrtype; | |
378 | hsk.addrsz = h->h_length; | |
379 | if (dowrite(fd, &hsk, sizeof(hsk))) | |
380 | return (-1); | |
381 | ||
382 | /* --- Send the name and alias strings --- */ | |
383 | ||
384 | if (putstring(fd, h->h_name)) | |
385 | return (-1); | |
386 | for (i = 0; h->h_aliases[i]; i++) { | |
387 | if (putstring(fd, h->h_aliases[i])) | |
388 | return (-1); | |
389 | } | |
390 | ||
391 | /* --- Send the address data --- */ | |
392 | ||
393 | for (i = 0; h->h_addr_list[i]; i++) { | |
394 | if (dowrite(fd, h->h_addr_list[i], hsk.addrsz)) | |
395 | return (-1); | |
396 | } | |
397 | ||
398 | /* --- OK, done --- */ | |
399 | ||
400 | return (0); | |
401 | } | |
402 | ||
403 | /*----- Resolver server ---------------------------------------------------*/ | |
404 | ||
405 | /* --- @child@ --- * | |
406 | * | |
407 | * Arguments: @int rfd@ = output file descriptor for resolved hostnames | |
408 | * @int cfd@ = input file descriptor for raw addresses | |
409 | * | |
410 | * Returns: Never. | |
411 | * | |
412 | * Use: Asynchronous name resolving process. | |
413 | */ | |
414 | ||
415 | static void child(int rfd, int cfd) | |
416 | { | |
417 | /* --- Close other file descriptors --- */ | |
418 | ||
419 | { | |
420 | int i; | |
5d6d2d94 | 421 | #if defined(_SC_OPEN_MAX) |
a759efa6 | 422 | int maxfd = sysconf(_SC_OPEN_MAX); |
5d6d2d94 | 423 | #elif defined(OPEN_MAX) |
424 | int maxfd = OPEN_MAX; | |
425 | #else | |
426 | int maxfd = -1; | |
427 | #endif | |
a759efa6 | 428 | |
429 | if (maxfd < 0) | |
430 | maxfd = 256; /* Fingers crossed... */ | |
431 | for (i = 0; i < maxfd; i++) { | |
432 | if (i != rfd && i != cfd && i != 1) | |
433 | close(i); | |
434 | } | |
435 | } | |
436 | ||
364308dc | 437 | signal(SIGTERM, SIG_DFL); |
438 | signal(SIGHUP, SIG_DFL); | |
439 | signal(SIGQUIT, SIG_DFL); | |
440 | signal(SIGALRM, SIG_DFL); | |
441 | signal(SIGINT, SIG_DFL); | |
442 | ||
a759efa6 | 443 | /* --- Main request/response loop --- */ |
444 | ||
445 | for (;;) { | |
446 | int req, resp; | |
447 | struct hostent *h; | |
448 | ||
449 | /* --- Read the request --- */ | |
450 | ||
451 | if (doread(cfd, &req, sizeof(req))) | |
452 | goto lose; | |
453 | ||
454 | /* --- Process it into a host structure --- */ | |
455 | ||
456 | switch (req) { | |
457 | ||
458 | /* --- Normal forward lookup --- */ | |
459 | ||
460 | case BRES_BYNAME: { | |
461 | char *name = getstring(cfd); | |
462 | if (!name) | |
463 | goto lose; | |
464 | h = gethostbyname(name); | |
465 | free(name); | |
466 | } break; | |
467 | ||
d8fe3fc2 | 468 | /* --- Reverse lookup --- */ |
a759efa6 | 469 | |
470 | case BRES_BYADDR: { | |
471 | struct in_addr addr; | |
472 | char *p; | |
473 | if (doread(cfd, &addr, sizeof(addr))) | |
474 | goto lose; | |
475 | if ((h = gethostbyaddr((char *)&addr, sizeof(addr), AF_INET)) == 0) | |
47aacebf | 476 | goto skip; |
a759efa6 | 477 | |
478 | /* --- Do a forward lookup to confirm --- */ | |
479 | ||
480 | { | |
481 | size_t sz = strlen(h->h_name) + 1; | |
482 | if ((p = malloc(sz)) == 0) | |
47aacebf | 483 | goto skip; |
a759efa6 | 484 | memcpy(p, h->h_name, sz); |
485 | } | |
486 | ||
487 | h = gethostbyname(p); | |
488 | free(p); | |
489 | if (!h) | |
47aacebf | 490 | goto skip; |
a759efa6 | 491 | if (h) { |
492 | char **pp; | |
493 | for (pp = h->h_addr_list; *pp; pp++) { | |
494 | struct in_addr a; | |
495 | memcpy(&a, *pp, sizeof(a)); | |
47aacebf MW |
496 | if (a.s_addr == addr.s_addr) |
497 | goto skip; | |
a759efa6 | 498 | } |
499 | } | |
47aacebf MW |
500 | h = 0; |
501 | h_errno = NO_RECOVERY; | |
502 | skip:; | |
a759efa6 | 503 | } break; |
504 | ||
505 | /* --- Unknown request -- may have lost sync --- */ | |
506 | ||
507 | default: | |
508 | goto lose; | |
509 | } | |
510 | ||
511 | /* --- Transmit the response --- */ | |
512 | ||
513 | if (h) { | |
514 | resp = BRES_HOSTENT; | |
515 | if (dowrite(rfd, &resp, sizeof(resp)) || puthost(rfd, h)) | |
516 | goto lose; | |
517 | } else { | |
518 | resp = BRES_ERROR; | |
519 | if (dowrite(rfd, &resp, sizeof(resp)) || | |
520 | dowrite(rfd, &h_errno, sizeof(h_errno))) | |
521 | goto lose; | |
522 | } | |
523 | } | |
524 | ||
525 | lose: | |
526 | _exit(1); | |
527 | } | |
528 | ||
529 | /* --- @main@ --- * | |
530 | * | |
531 | * Arguments: @int argc@ = number of command line arguments | |
532 | * @char *argv[]@ = array of arguments | |
533 | * | |
534 | * Returns: Runs until killed or an error occurs. | |
535 | * | |
536 | * Use: A name resolver server process for mLib programs which need | |
537 | * this sort of thing. | |
538 | */ | |
539 | ||
540 | #ifdef BRES_STANDALONE | |
541 | ||
542 | int main(int argc, char *argv[]) | |
543 | { | |
544 | if (isatty(STDIN_FILENO)) { | |
545 | char *p = strrchr(argv[0], '/'); | |
546 | if (p) | |
547 | p++; | |
548 | else | |
549 | p = argv[0]; | |
550 | fprintf(stderr, | |
551 | "%s: don't run this program unless you know what you're doing.\n", | |
552 | p); | |
553 | exit(1); | |
554 | } | |
555 | child(STDOUT_FILENO, STDIN_FILENO); | |
556 | return (1); | |
557 | } | |
558 | ||
559 | #endif | |
560 | ||
561 | /*----- Main code ---------------------------------------------------------*/ | |
562 | ||
563 | #ifndef BRES_STANDALONE | |
564 | ||
565 | /* --- @zap@ --- * | |
566 | * | |
567 | * Arguments: @bres_server *rs@ = pointer to server block | |
568 | * | |
569 | * Returns: --- | |
570 | * | |
571 | * Use: Kills a server process, reaps the losing child and makes | |
572 | * things generally clean again. | |
573 | */ | |
574 | ||
575 | static void zap(bres_server *rs) | |
576 | { | |
577 | /* --- Close the pipes, kill the child, and reap it --- */ | |
578 | ||
579 | if (rs->kid != -1) { | |
580 | close(rs->fd); | |
581 | close(rs->f.fd); | |
582 | kill(rs->kid, SIGTERM); | |
583 | waitpid(rs->kid, 0, 0); | |
584 | rs->kid = -1; | |
585 | } | |
586 | ||
587 | /* --- Move the server to the back of the list --- */ | |
588 | ||
a736dc9c | 589 | if (!rs->rc) UNLINK(freelist, freetail, rs); |
ffb41122 | 590 | LINKTAIL(freelist, freetail, rs); |
a759efa6 | 591 | } |
592 | ||
593 | /* --- @bres_abort@ --- * | |
594 | * | |
595 | * Arguments: @bres_client *rc@ = pointer to client block | |
596 | * | |
597 | * Returns: --- | |
598 | * | |
599 | * Use: Removes a queued job. | |
600 | */ | |
601 | ||
602 | void bres_abort(bres_client *rc) | |
603 | { | |
604 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 605 | xfree(rc->u.name); |
ffb41122 MW |
606 | if (!rc->rs) |
607 | UNLINK(qhead, qtail, rc); | |
608 | else { | |
a759efa6 | 609 | sel_rmfile(&rc->rs->f); |
610 | zap(rc->rs); | |
611 | rc->rs = 0; | |
a759efa6 | 612 | } |
613 | } | |
614 | ||
615 | /* --- @idle@ --- * | |
616 | * | |
617 | * Arguments: @struct timeval *tv@ = pointer to the current time | |
618 | * @void *vp@ = pointer to a server block | |
619 | * | |
620 | * Returns: --- | |
621 | * | |
622 | * Use: Kills off a child which has been idle for too long. | |
623 | */ | |
624 | ||
625 | static void idle(struct timeval *tv, void *vp) | |
626 | { | |
627 | bres_server *rs = vp; | |
628 | zap(rs); | |
629 | } | |
630 | ||
631 | /* --- @answer@ --- * | |
632 | * | |
633 | * Arguments: @int fd@ = file descriptor which is ready | |
634 | * @unsigned mode@ = what it's doing now | |
635 | * @void *vp@ = pointer to server block | |
636 | * | |
637 | * Returns: --- | |
638 | * | |
639 | * Use: Retrieves an answer from a name resolver process. | |
640 | */ | |
641 | ||
642 | static void attach(bres_client */*rc*/); | |
643 | ||
644 | static void answer(int fd, unsigned mode, void *vp) | |
645 | { | |
646 | bres_server *rs = vp; | |
647 | bres_client *rc = rs->rc; | |
648 | struct hostent *h = 0; | |
649 | int resp; | |
650 | int fail = 1; | |
651 | ||
652 | /* --- Report the result to my client --- */ | |
653 | ||
654 | sel_rmfile(&rs->f); | |
655 | h_errno = -1; | |
656 | if (doread(fd, &resp, sizeof(resp)) == 0) { | |
657 | switch (resp) { | |
658 | case BRES_ERROR: | |
659 | doread(fd, &h_errno, sizeof(h_errno)); | |
660 | fail = 0; | |
661 | break; | |
662 | case BRES_HOSTENT: | |
663 | h = gethost(fd); | |
664 | fail = 0; | |
665 | break; | |
666 | } | |
667 | } | |
668 | if (rc) { | |
669 | rc->func(h, rc->p); | |
670 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 671 | xfree(rc->u.name); |
a759efa6 | 672 | } |
673 | if (h) | |
d8fe3fc2 | 674 | free(h); |
a759efa6 | 675 | if (fail) |
676 | zap(rs); | |
677 | if (!rc) | |
678 | return; | |
679 | ||
680 | /* --- Wrap up the various structures --- */ | |
681 | ||
682 | rs->rc = 0; | |
683 | rc->rs = 0; | |
ffb41122 | 684 | LINKHEAD(freelist, freetail, rs); |
a759efa6 | 685 | |
686 | /* --- Tie a timer onto the server block --- */ | |
687 | ||
688 | { | |
689 | struct timeval tv; | |
690 | ||
691 | gettimeofday(&tv, 0); | |
692 | tv.tv_sec += BRES_IDLE; | |
693 | sel_addtimer(sel, &rs->t, &tv, idle, rs); | |
694 | } | |
695 | ||
696 | /* --- If there are any clients waiting, attach one --- */ | |
697 | ||
ffb41122 MW |
698 | if (qhead) { |
699 | rc = qhead; | |
700 | UNLINK(qhead, qtail, rc); | |
a759efa6 | 701 | attach(rc); |
702 | } | |
703 | } | |
704 | ||
705 | /* --- @start@ --- * | |
706 | * | |
707 | * Arguments: @bres_server *rs@ = pointer to a server block | |
708 | * | |
709 | * Returns: Zero if OK, nonzero if something failed. | |
710 | * | |
711 | * Use: Starts up a child resolver process. | |
712 | */ | |
713 | ||
714 | static int start(bres_server *rs) | |
715 | { | |
716 | int rfd[2], cfd[2]; | |
717 | pid_t kid; | |
ff1e93ac | 718 | mdup_fd md[2]; |
a759efa6 | 719 | |
720 | /* --- Make the pipes --- */ | |
721 | ||
722 | if (pipe(rfd)) | |
723 | goto fail_0; | |
724 | if (pipe(cfd)) | |
725 | goto fail_1; | |
726 | ||
727 | /* --- Start up the child process --- */ | |
728 | ||
729 | if ((kid = fork()) < 0) | |
730 | goto fail_2; | |
731 | if (kid == 0) { | |
732 | close(cfd[1]); | |
733 | close(rfd[0]); | |
734 | ||
735 | if (server) { | |
ff1e93ac MW |
736 | md[0].cur = cfd[0]; md[0].want = STDIN_FILENO; |
737 | md[1].cur = rfd[1]; md[1].want = STDOUT_FILENO; | |
738 | if (mdup(md, 2) || execlp(server, server, (char *)0)) | |
739 | child(STDOUT_FILENO, STDIN_FILENO); | |
a759efa6 | 740 | } else |
741 | child(rfd[1], cfd[0]); | |
742 | _exit(1); | |
743 | } | |
744 | ||
745 | /* --- Fix up everything in the server block --- */ | |
746 | ||
747 | close(cfd[0]); | |
748 | close(rfd[1]); | |
749 | rs->fd = cfd[1]; | |
750 | sel_initfile(sel, &rs->f, rfd[0], SEL_READ, answer, rs); | |
751 | rs->kid = kid; | |
752 | return (0); | |
753 | ||
754 | /* --- Fix up after errors --- */ | |
755 | ||
756 | fail_2: | |
757 | close(cfd[0]); | |
758 | close(cfd[1]); | |
759 | fail_1: | |
760 | close(rfd[0]); | |
761 | close(rfd[1]); | |
762 | fail_0: | |
763 | return (-1); | |
764 | } | |
765 | ||
766 | /* --- @attach@ --- * | |
767 | * | |
768 | * Arguments: @bres_client *rc@ = pointer to a client block | |
769 | * | |
770 | * Returns: --- | |
771 | * | |
772 | * Use: Attaches a client to a spare server (which is assumed to | |
773 | * exist). | |
774 | */ | |
775 | ||
776 | static void attach(bres_client *rc) | |
777 | { | |
778 | bres_server *rs; | |
779 | int lose = 0; | |
780 | ||
781 | /* --- Fix up the server ready for the job --- * | |
782 | * | |
783 | * If the server has a process, remove its timer. Otherwise, fork off a | |
784 | * new resolver process. This is also where I go if I find that the child | |
785 | * resolver process has lost while I wasn't looking. Only one attempt at | |
786 | * forking is performed. | |
787 | */ | |
788 | ||
789 | again: | |
ffb41122 | 790 | rs = freelist; |
a759efa6 | 791 | if (rs->kid != -1) |
792 | sel_rmtimer(&rs->t); | |
793 | else { | |
794 | if (lose || start(rs)) | |
795 | goto lost; | |
796 | lose = 1; | |
797 | } | |
798 | ||
799 | /* --- Submit the job to the resolver --- */ | |
800 | ||
801 | { | |
802 | struct sigaction sa, osa; | |
803 | int e; | |
804 | ||
805 | /* --- Ignore @SIGPIPE@ for now --- * | |
806 | * | |
807 | * This way I can trap @EPIPE@ and reap a losing child, if there was one. | |
808 | */ | |
809 | ||
810 | sa.sa_handler = SIG_IGN; | |
811 | sa.sa_flags = 0; | |
812 | sigemptyset(&sa.sa_mask); | |
813 | sigaction(SIGPIPE, &sa, &osa); | |
814 | ||
815 | /* --- Write the new job to the child --- */ | |
816 | ||
817 | e = 0; | |
818 | if (dowrite(rs->fd, &rc->q, sizeof(rc->q))) | |
819 | e = errno; | |
820 | else switch (rc->q) { | |
821 | case BRES_BYADDR: | |
822 | if (dowrite(rs->fd, &rc->u.addr, sizeof(rc->u.addr))) | |
823 | e = errno; | |
824 | break; | |
825 | case BRES_BYNAME: | |
826 | if (putstring(rs->fd, rc->u.name)) | |
827 | e = errno; | |
828 | break; | |
829 | } | |
830 | sigaction(SIGPIPE, &osa, 0); | |
831 | ||
832 | /* --- Sort out various errors --- * | |
833 | * | |
834 | * This was once more complicated, handling @EPIPE@ separately from other | |
835 | * errors. Now everything's handled the same way. | |
836 | */ | |
837 | ||
838 | if (e) { | |
839 | zap(rs); | |
840 | goto again; | |
841 | } | |
842 | } | |
843 | ||
844 | /* --- Fiddle with lists so that everything's OK --- */ | |
845 | ||
846 | sel_addfile(&rs->f); | |
ffb41122 | 847 | UNLINK(freelist, freetail, rs); |
a759efa6 | 848 | rs->rc = rc; |
849 | rc->rs = rs; | |
850 | return; | |
851 | ||
852 | lost: | |
853 | rc->func(0, rc->p); | |
854 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 855 | xfree(rc->u.name); |
a759efa6 | 856 | } |
857 | ||
858 | /* --- @resolve@ --- * | |
859 | * | |
860 | * Arguments: @bres_client *rc@ = pointer to filled-in client block | |
861 | * | |
862 | * Returns: --- | |
863 | * | |
864 | * Use: Dispatcher for incoming resolution jobs. | |
865 | */ | |
866 | ||
867 | static void resolve(bres_client *rc) | |
868 | { | |
869 | /* --- If there's a free server, plug it in --- */ | |
870 | ||
871 | rc->rs = 0; | |
ffb41122 | 872 | if (freelist) |
a759efa6 | 873 | attach(rc); |
ffb41122 MW |
874 | else |
875 | LINKTAIL(qhead, qtail, rc); | |
a759efa6 | 876 | } |
877 | ||
878 | /* --- @bres_byaddr@ --- * | |
879 | * | |
880 | * Arguments: @bres_client *rc@ = pointer to client block | |
881 | * @struct in_addr addr@ = address to resolve | |
882 | * @void (*func)(struct hostent *h, void *p)@ = handler function | |
883 | * @void *p@ = argument for handler function | |
884 | * | |
885 | * Returns: --- | |
886 | * | |
887 | * Use: Adds an address lookup job to the queue. The job will be | |
888 | * processed when there's a spare resolver process to deal with | |
889 | * it. | |
890 | */ | |
891 | ||
892 | void bres_byaddr(bres_client *rc, struct in_addr addr, | |
893 | void (*func)(struct hostent */*h*/, void */*p*/), | |
894 | void *p) | |
895 | { | |
896 | rc->q = BRES_BYADDR; | |
897 | rc->u.addr = addr; | |
898 | rc->func = func; | |
899 | rc->p = p; | |
900 | resolve(rc); | |
901 | } | |
902 | ||
903 | /* --- @bres_byname@ --- * | |
904 | * | |
905 | * Arguments: @bres_client *rc@ = pointer to client block | |
906 | * @const char *name@ = name to resolve | |
907 | * @void (*func)(struct hostent *h, void *p)@ = handler function | |
908 | * @void *p@ = argument for handler function | |
909 | * | |
910 | * Returns: --- | |
911 | * | |
912 | * Use: Adds a name lookup job to the queue. The job will be | |
913 | * processed when there's a spare resolver process to deal with | |
914 | * it. | |
915 | */ | |
916 | ||
917 | void bres_byname(bres_client *rc, const char *name, | |
918 | void (*func)(struct hostent */*h*/, void */*p*/), | |
919 | void *p) | |
920 | { | |
921 | rc->q = BRES_BYNAME; | |
922 | rc->u.name = xstrdup(name); | |
923 | rc->func = func; | |
924 | rc->p = p; | |
925 | resolve(rc); | |
926 | } | |
927 | ||
928 | /* --- @bres_exec@ --- * | |
929 | * | |
930 | * Arguments: @const char *file@ = file containing server code or null | |
931 | * | |
932 | * Returns: --- | |
933 | * | |
934 | * Use: Makes `bres' use a standalone server rather than copies of | |
935 | * the current process. This can reduce memory consumption for | |
936 | * large processes, at the expense of startup time (which | |
937 | * shouldn't be too bad anyway, because of the resolver design). | |
938 | * If the filename is null, a default set up at install time is | |
939 | * used. It's probably a good idea to leave it alone. | |
940 | */ | |
941 | ||
942 | void bres_exec(const char *file) | |
943 | { | |
944 | if (file) | |
945 | server = file; | |
946 | else | |
947 | server = BRES_SERVER; | |
948 | } | |
949 | ||
950 | /* --- @bres_init@ --- * | |
951 | * | |
952 | * Arguments: @sel_state *s@ = pointer to select multiplexor | |
953 | * | |
954 | * Returns: --- | |
955 | * | |
956 | * Use: Initializes the background resolver for use. | |
957 | */ | |
958 | ||
959 | void bres_init(sel_state *s) | |
960 | { | |
961 | int i; | |
962 | ||
963 | sel = s; | |
964 | for (i = 0; i < BRES_MAX; i++) { | |
a759efa6 | 965 | servers[i].kid = -1; |
966 | servers[i].rc = 0; | |
ffb41122 | 967 | LINKTAIL(freelist, freetail, &servers[i]); |
a759efa6 | 968 | } |
969 | } | |
970 | ||
971 | #endif | |
972 | ||
973 | /*----- That's all, folks -------------------------------------------------*/ |