Commit | Line | Data |
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a759efa6 | 1 | /* -*-c-*- |
2 | * | |
8656dc50 | 3 | * $Id: bres.c,v 1.7 2004/04/08 01:36:11 mdw Exp $ |
a759efa6 | 4 | * |
5 | * Background reverse name resolution | |
6 | * | |
7 | * (c) 1999 Straylight/Edgeware | |
8 | */ | |
9 | ||
d4efbcd9 | 10 | /*----- Licensing notice --------------------------------------------------* |
a759efa6 | 11 | * |
12 | * This file is part of the mLib utilities library. | |
13 | * | |
14 | * mLib is free software; you can redistribute it and/or modify | |
15 | * it under the terms of the GNU Library General Public License as | |
16 | * published by the Free Software Foundation; either version 2 of the | |
17 | * License, or (at your option) any later version. | |
d4efbcd9 | 18 | * |
a759efa6 | 19 | * mLib 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 Library General Public License for more details. | |
d4efbcd9 | 23 | * |
a759efa6 | 24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with mLib; if not, write to the Free | |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
27 | * MA 02111-1307, USA. | |
28 | */ | |
29 | ||
a759efa6 | 30 | /*----- Header files ------------------------------------------------------*/ |
31 | ||
a0150d8d MW |
32 | #include "config.h" |
33 | ||
a759efa6 | 34 | #include <errno.h> |
35 | #include <signal.h> | |
36 | #include <stdio.h> | |
37 | #include <stdlib.h> | |
38 | #include <string.h> | |
39 | ||
40 | #include <sys/types.h> | |
41 | #include <sys/time.h> | |
42 | #include <unistd.h> | |
43 | #include <sys/wait.h> | |
44 | ||
45 | #include <sys/socket.h> | |
46 | #include <netinet/in.h> | |
47 | #include <arpa/inet.h> | |
48 | #include <netdb.h> | |
49 | ||
6c3a7cf7 | 50 | #include "alloc.h" |
a759efa6 | 51 | #include "bres.h" |
6c3a7cf7 | 52 | #include "report.h" |
53 | #include "sel.h" | |
a759efa6 | 54 | |
55 | /*----- Magic numbers -----------------------------------------------------*/ | |
56 | ||
57 | #define BRES_MAX 15 /* Maximum number of resolvers */ | |
58 | #define BRES_IDLE 60 /* Lifetime of an idle resolver */ | |
59 | ||
60 | /*----- Static variables --------------------------------------------------*/ | |
61 | ||
62 | #ifndef BRES_STANDALONE | |
63 | ||
64 | static bres_server servers[BRES_MAX]; /* Statically allocated servers */ | |
65 | ||
66 | #define FREE ((bres_server *)&freelist) | |
67 | static struct { bres_server *next, *prev; } freelist = { FREE, FREE }; | |
68 | ||
69 | #define QUEUE ((bres_client *)&queue) | |
70 | static struct { bres_client *next, *prev; } queue = { QUEUE, QUEUE }; | |
71 | ||
72 | static sel_state *sel; | |
73 | ||
74 | static const char *server = 0; | |
75 | ||
76 | #endif | |
77 | ||
78 | /*----- Background resolver protocol --------------------------------------*/ | |
79 | ||
80 | /* --- Requests and responses --- * | |
81 | * | |
82 | * There are two types of requests: name and addr, corresponding to the | |
83 | * standard @gethostbyname@ and @gethostbyaddr@ calls. There are two types | |
84 | * of responses too: a positive response consists of an encoded equivalent of | |
85 | * a @struct hostent@ structure containing the requested information; a | |
86 | * negative response consists of an @h_errno@ value explaining the problem. | |
87 | */ | |
88 | ||
89 | #define BRES_BYNAME 0 /* Request: resolve given name */ | |
90 | #define BRES_BYADDR 1 /* Request: resolve given address */ | |
91 | ||
92 | #define BRES_HOSTENT 0 /* Response: resolved ok */ | |
93 | #define BRES_ERROR 1 /* Response: resolution failed */ | |
94 | ||
95 | /* --- Encodings --- * | |
96 | * | |
97 | * A string is encoded as a @size_t@ length followed by the actual data. The | |
98 | * null terminator is not transmitted. | |
99 | * | |
100 | * Addresses for resolution are transmitted as raw @struct in_addr@ | |
101 | * structures. | |
102 | * | |
103 | * A @hostent@ structure is transmitted as a header containing fixed-size | |
104 | * information, followed by the official name, an array of aliases, and an | |
105 | * array of addresses. The number of items in the arrays is specified in the | |
106 | * header. | |
107 | * | |
108 | * The implementation assumes that a complete request or reply is always | |
109 | * sent. Undesirable blocking will occur if this is not the case. Both ends | |
110 | * are assumed to trust each other. A protocol failure results in the child | |
111 | * in question being terminated. | |
112 | */ | |
113 | ||
114 | typedef struct hostskel { | |
115 | size_t nalias; | |
116 | int addrtype; | |
117 | size_t addrsz; | |
118 | size_t naddr; | |
119 | } hostskel; | |
120 | ||
121 | /* --- @doread@, @dowrite@ --- * | |
122 | * | |
123 | * Arguments: @int fd@ = file descriptor | |
124 | * @void *buf@ = buffer for data | |
125 | * @size_t sz@ = size of data | |
126 | * | |
127 | * Returns: Zero if successful, nonzero otherwise. | |
128 | * | |
129 | * Use: Reads or writes a chunk of data. @EINTR@ errors are retried; | |
130 | * incomplete reads and writes are continued from where they | |
131 | * left off. End-of-file is considered an I/O error. | |
132 | */ | |
133 | ||
134 | static int doread(int fd, void *buf, size_t sz) | |
135 | { | |
136 | char *p = buf; | |
137 | while (sz) { | |
138 | int r = read(fd, p, sz); | |
139 | if (r < 0) { | |
140 | if (errno == EINTR) | |
141 | continue; | |
142 | return (-1); | |
143 | } else if (r == 0) { | |
144 | errno = EIO; | |
145 | return (-1); | |
146 | } | |
147 | sz -= r; | |
148 | p += r; | |
149 | } | |
150 | return (0); | |
151 | } | |
152 | ||
153 | static int dowrite(int fd, const void *buf, size_t sz) | |
154 | { | |
155 | const char *p = buf; | |
156 | while (sz) { | |
157 | int r = write(fd, p, sz); | |
158 | if (r < 0) { | |
159 | if (errno == EINTR) | |
160 | continue; | |
161 | return (-1); | |
162 | } else if (r == 0) { | |
163 | errno = EIO; | |
164 | return (-1); | |
165 | } | |
166 | sz -= r; | |
167 | p += r; | |
168 | } | |
169 | return (0); | |
170 | } | |
171 | ||
172 | /* --- @getstring@ --- * | |
173 | * | |
174 | * Arguments: @int fd@ = file descriptor to read | |
175 | * | |
176 | * Returns: String in heap-allocated block, or a null pointer. | |
177 | * | |
178 | * Use: Decodes a string. | |
179 | */ | |
180 | ||
181 | static char *getstring(int fd) | |
182 | { | |
183 | size_t sz; | |
184 | char *p; | |
185 | ||
186 | if (doread(fd, &sz, sizeof(sz)) || (p = malloc(sz + 1)) == 0) | |
187 | return (0); | |
188 | if (doread(fd, p, sz)) { | |
189 | free(p); | |
190 | return (0); | |
191 | } | |
192 | p[sz] = 0; | |
193 | return (p); | |
194 | } | |
195 | ||
196 | /* --- @putstring@ --- * | |
197 | * | |
198 | * Arguments: @int fd@ = file descriptor to write on | |
199 | * @const char *p@ = pointer to string to write | |
200 | * | |
201 | * Returns: Zero if successful. | |
202 | * | |
203 | * Use: Encodes a string. | |
204 | */ | |
205 | ||
206 | static int putstring(int fd, const char *p) | |
207 | { | |
208 | size_t sz = strlen(p); | |
209 | if (dowrite(fd, &sz, sizeof(sz)) || dowrite(fd, p, sz)) | |
210 | return (-1); | |
211 | return (0); | |
212 | } | |
213 | ||
214 | /* --- @gethost@ --- * | |
215 | * | |
216 | * Arguments: @int fd@ = file descriptor to read | |
217 | * | |
218 | * Returns: Pointer to heap-allocated @struct hostent@, or null. | |
219 | * | |
220 | * Use: Decodes a host structure. The resulting structure is all in | |
221 | * one big heap block. | |
222 | */ | |
223 | ||
224 | #ifndef BRES_STANDALONE | |
225 | ||
226 | static struct hostent *gethost(int fd) | |
227 | { | |
228 | hostskel hsk; | |
229 | struct hostent *h; | |
230 | char *name; | |
231 | char **alias = 0; | |
d4efbcd9 | 232 | |
a759efa6 | 233 | /* --- Read the skeleton structure --- */ |
234 | ||
235 | if (doread(fd, &hsk, sizeof(hsk))) | |
236 | goto tidy_0; | |
237 | ||
238 | /* --- Read the hostname and alias strings --- * | |
239 | * | |
240 | * Count the length of the strings as we go. | |
241 | */ | |
242 | ||
243 | { | |
244 | size_t sz = | |
245 | sizeof(struct hostent) + | |
246 | hsk.naddr * hsk.addrsz + | |
247 | (hsk.naddr + hsk.nalias + 2) * sizeof(char *); | |
248 | ||
249 | /* --- Read the primary host name --- */ | |
250 | ||
251 | if ((name = getstring(fd)) == 0) | |
252 | goto tidy_0; | |
253 | sz += strlen(name) + 1; | |
254 | ||
255 | /* --- Read in the alias names --- */ | |
256 | ||
257 | if (hsk.nalias) { | |
258 | int i; | |
259 | if ((alias = malloc(hsk.nalias * sizeof(char *))) == 0) | |
d4efbcd9 | 260 | goto tidy_1; |
a759efa6 | 261 | for (i = 0; i < hsk.nalias; i++) |
262 | alias[i] = 0; | |
263 | for (i = 0; i < hsk.nalias; i++) { | |
264 | if ((alias[i] = getstring(fd)) == 0) | |
265 | goto tidy_2; | |
266 | sz += strlen(alias[i]) + 1; | |
267 | } | |
268 | } | |
269 | ||
270 | /* --- Allocate the output structure --- */ | |
271 | ||
272 | if ((h = malloc(sz)) == 0) | |
273 | goto tidy_2; | |
274 | } | |
275 | ||
276 | /* --- Fill in the base structure --- */ | |
277 | ||
278 | h->h_addrtype = hsk.addrtype; | |
279 | h->h_length = hsk.addrsz; | |
280 | ||
281 | /* --- Start putting everything else in --- */ | |
282 | ||
283 | { | |
284 | char **p = (char **)(h + 1); | |
285 | char *a = (char *)(p + hsk.nalias + hsk.naddr + 2); | |
286 | int i; | |
287 | ||
288 | /* --- Start with the address table --- */ | |
289 | ||
290 | h->h_addr_list = p; | |
291 | if (doread(fd, a, hsk.naddr * hsk.addrsz)) | |
292 | goto tidy_2; | |
293 | for (i = 0; i < hsk.naddr; i++) { | |
a759efa6 | 294 | *p++ = a; |
364308dc | 295 | a += hsk.addrsz; |
a759efa6 | 296 | } |
297 | *p++ = 0; | |
298 | ||
299 | /* --- Finally copy the strings over --- */ | |
300 | ||
301 | #define PUT(_p) do { \ | |
302 | size_t _len = strlen(_p) + 1; \ | |
303 | memcpy(a, (_p), _len); \ | |
304 | a += _len; \ | |
305 | } while (0) | |
306 | ||
307 | h->h_name = a; | |
308 | PUT(name); | |
d8fe3fc2 | 309 | free(name); |
a759efa6 | 310 | h->h_aliases = p; |
311 | for (i = 0; i < hsk.nalias; i++) { | |
312 | *p++ = a; | |
313 | PUT(alias[i]); | |
d8fe3fc2 | 314 | free(alias[i]); |
a759efa6 | 315 | } |
316 | *p++ = 0; | |
d8fe3fc2 | 317 | free(alias); |
d4efbcd9 | 318 | |
a759efa6 | 319 | #undef PUT |
320 | } | |
321 | ||
322 | return (h); | |
323 | ||
324 | /* --- Tidy up after various types of failure --- */ | |
325 | ||
326 | tidy_2: | |
327 | { | |
328 | int i; | |
329 | for (i = 0; i < hsk.nalias && alias[i]; i++) | |
d8fe3fc2 | 330 | free(alias[i]); |
331 | free(alias); | |
a759efa6 | 332 | } |
333 | tidy_1: | |
d8fe3fc2 | 334 | free(name); |
a759efa6 | 335 | tidy_0: |
336 | return (0); | |
337 | } | |
338 | ||
339 | #endif | |
340 | ||
341 | /* --- @puthost@ --- * | |
342 | * | |
343 | * Arguments: @int fd@ = file descriptor | |
344 | * @struct hostent *h@ = pointer to host structure | |
345 | * | |
346 | * Returns: Zero if successful. | |
347 | * | |
348 | * Use: Encodes a host structure. | |
349 | */ | |
350 | ||
351 | static int puthost(int fd, struct hostent *h) | |
352 | { | |
353 | hostskel hsk; | |
354 | int i; | |
355 | ||
356 | /* --- Fill in and send the skeleton structure --- */ | |
357 | ||
358 | for (i = 0; h->h_aliases[i]; i++) | |
359 | ; | |
360 | hsk.nalias = i; | |
361 | for (i = 0; h->h_addr_list[i]; i++) | |
362 | ; | |
363 | hsk.naddr = i; | |
364 | hsk.addrtype = h->h_addrtype; | |
365 | hsk.addrsz = h->h_length; | |
366 | if (dowrite(fd, &hsk, sizeof(hsk))) | |
367 | return (-1); | |
368 | ||
369 | /* --- Send the name and alias strings --- */ | |
370 | ||
371 | if (putstring(fd, h->h_name)) | |
372 | return (-1); | |
373 | for (i = 0; h->h_aliases[i]; i++) { | |
374 | if (putstring(fd, h->h_aliases[i])) | |
375 | return (-1); | |
376 | } | |
377 | ||
378 | /* --- Send the address data --- */ | |
379 | ||
380 | for (i = 0; h->h_addr_list[i]; i++) { | |
381 | if (dowrite(fd, h->h_addr_list[i], hsk.addrsz)) | |
382 | return (-1); | |
383 | } | |
384 | ||
385 | /* --- OK, done --- */ | |
386 | ||
387 | return (0); | |
388 | } | |
389 | ||
390 | /*----- Resolver server ---------------------------------------------------*/ | |
391 | ||
392 | /* --- @child@ --- * | |
393 | * | |
394 | * Arguments: @int rfd@ = output file descriptor for resolved hostnames | |
395 | * @int cfd@ = input file descriptor for raw addresses | |
396 | * | |
397 | * Returns: Never. | |
398 | * | |
399 | * Use: Asynchronous name resolving process. | |
400 | */ | |
401 | ||
402 | static void child(int rfd, int cfd) | |
403 | { | |
404 | /* --- Close other file descriptors --- */ | |
405 | ||
406 | { | |
407 | int i; | |
5d6d2d94 | 408 | #if defined(_SC_OPEN_MAX) |
a759efa6 | 409 | int maxfd = sysconf(_SC_OPEN_MAX); |
5d6d2d94 | 410 | #elif defined(OPEN_MAX) |
411 | int maxfd = OPEN_MAX; | |
412 | #else | |
413 | int maxfd = -1; | |
414 | #endif | |
a759efa6 | 415 | |
416 | if (maxfd < 0) | |
417 | maxfd = 256; /* Fingers crossed... */ | |
418 | for (i = 0; i < maxfd; i++) { | |
419 | if (i != rfd && i != cfd && i != 1) | |
420 | close(i); | |
421 | } | |
422 | } | |
423 | ||
364308dc | 424 | signal(SIGTERM, SIG_DFL); |
425 | signal(SIGHUP, SIG_DFL); | |
426 | signal(SIGQUIT, SIG_DFL); | |
427 | signal(SIGALRM, SIG_DFL); | |
428 | signal(SIGINT, SIG_DFL); | |
429 | ||
a759efa6 | 430 | /* --- Main request/response loop --- */ |
431 | ||
432 | for (;;) { | |
433 | int req, resp; | |
434 | struct hostent *h; | |
435 | ||
436 | /* --- Read the request --- */ | |
437 | ||
438 | if (doread(cfd, &req, sizeof(req))) | |
439 | goto lose; | |
440 | ||
441 | /* --- Process it into a host structure --- */ | |
442 | ||
443 | switch (req) { | |
444 | ||
445 | /* --- Normal forward lookup --- */ | |
446 | ||
447 | case BRES_BYNAME: { | |
448 | char *name = getstring(cfd); | |
449 | if (!name) | |
450 | goto lose; | |
451 | h = gethostbyname(name); | |
452 | free(name); | |
453 | } break; | |
454 | ||
d8fe3fc2 | 455 | /* --- Reverse lookup --- */ |
a759efa6 | 456 | |
457 | case BRES_BYADDR: { | |
458 | struct in_addr addr; | |
459 | char *p; | |
460 | if (doread(cfd, &addr, sizeof(addr))) | |
461 | goto lose; | |
462 | if ((h = gethostbyaddr((char *)&addr, sizeof(addr), AF_INET)) == 0) | |
463 | goto fail; | |
464 | ||
465 | /* --- Do a forward lookup to confirm --- */ | |
466 | ||
467 | { | |
468 | size_t sz = strlen(h->h_name) + 1; | |
469 | if ((p = malloc(sz)) == 0) | |
470 | goto fail; | |
471 | memcpy(p, h->h_name, sz); | |
472 | } | |
473 | ||
474 | h = gethostbyname(p); | |
475 | free(p); | |
476 | if (!h) | |
477 | goto fail; | |
478 | p = 0; | |
479 | if (h) { | |
480 | char **pp; | |
481 | for (pp = h->h_addr_list; *pp; pp++) { | |
482 | struct in_addr a; | |
483 | memcpy(&a, *pp, sizeof(a)); | |
484 | if (a.s_addr == addr.s_addr) { | |
485 | p = h->h_name; | |
486 | break; | |
487 | } | |
488 | } | |
489 | } | |
490 | if (!p) { | |
491 | h = 0; | |
492 | h_errno = NO_RECOVERY; | |
493 | } | |
494 | fail:; | |
495 | } break; | |
496 | ||
497 | /* --- Unknown request -- may have lost sync --- */ | |
498 | ||
499 | default: | |
500 | goto lose; | |
501 | } | |
502 | ||
503 | /* --- Transmit the response --- */ | |
504 | ||
505 | if (h) { | |
506 | resp = BRES_HOSTENT; | |
507 | if (dowrite(rfd, &resp, sizeof(resp)) || puthost(rfd, h)) | |
508 | goto lose; | |
509 | } else { | |
510 | resp = BRES_ERROR; | |
511 | if (dowrite(rfd, &resp, sizeof(resp)) || | |
512 | dowrite(rfd, &h_errno, sizeof(h_errno))) | |
513 | goto lose; | |
514 | } | |
515 | } | |
516 | ||
517 | lose: | |
518 | _exit(1); | |
519 | } | |
520 | ||
521 | /* --- @main@ --- * | |
522 | * | |
523 | * Arguments: @int argc@ = number of command line arguments | |
524 | * @char *argv[]@ = array of arguments | |
525 | * | |
526 | * Returns: Runs until killed or an error occurs. | |
527 | * | |
528 | * Use: A name resolver server process for mLib programs which need | |
529 | * this sort of thing. | |
530 | */ | |
531 | ||
532 | #ifdef BRES_STANDALONE | |
533 | ||
534 | int main(int argc, char *argv[]) | |
535 | { | |
536 | if (isatty(STDIN_FILENO)) { | |
537 | char *p = strrchr(argv[0], '/'); | |
538 | if (p) | |
539 | p++; | |
540 | else | |
541 | p = argv[0]; | |
542 | fprintf(stderr, | |
543 | "%s: don't run this program unless you know what you're doing.\n", | |
544 | p); | |
545 | exit(1); | |
546 | } | |
547 | child(STDOUT_FILENO, STDIN_FILENO); | |
548 | return (1); | |
549 | } | |
550 | ||
551 | #endif | |
552 | ||
553 | /*----- Main code ---------------------------------------------------------*/ | |
554 | ||
555 | #ifndef BRES_STANDALONE | |
556 | ||
557 | /* --- @zap@ --- * | |
558 | * | |
559 | * Arguments: @bres_server *rs@ = pointer to server block | |
560 | * | |
561 | * Returns: --- | |
562 | * | |
563 | * Use: Kills a server process, reaps the losing child and makes | |
564 | * things generally clean again. | |
565 | */ | |
566 | ||
567 | static void zap(bres_server *rs) | |
568 | { | |
569 | /* --- Close the pipes, kill the child, and reap it --- */ | |
570 | ||
571 | if (rs->kid != -1) { | |
572 | close(rs->fd); | |
573 | close(rs->f.fd); | |
574 | kill(rs->kid, SIGTERM); | |
575 | waitpid(rs->kid, 0, 0); | |
576 | rs->kid = -1; | |
577 | } | |
578 | ||
579 | /* --- Move the server to the back of the list --- */ | |
580 | ||
581 | rs->next->prev = rs->prev; | |
582 | rs->prev->next = rs->next; | |
583 | rs->next = FREE; | |
584 | rs->prev = FREE->prev; | |
585 | FREE->prev->next = rs; | |
586 | FREE->prev = rs; | |
587 | } | |
588 | ||
589 | /* --- @bres_abort@ --- * | |
590 | * | |
591 | * Arguments: @bres_client *rc@ = pointer to client block | |
592 | * | |
593 | * Returns: --- | |
594 | * | |
595 | * Use: Removes a queued job. | |
596 | */ | |
597 | ||
598 | void bres_abort(bres_client *rc) | |
599 | { | |
600 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 601 | xfree(rc->u.name); |
a759efa6 | 602 | if (rc->rs) { |
603 | sel_rmfile(&rc->rs->f); | |
604 | zap(rc->rs); | |
605 | rc->rs = 0; | |
606 | } else { | |
607 | rc->next->prev = rc->prev; | |
608 | rc->prev->next = rc->next; | |
609 | } | |
610 | } | |
611 | ||
612 | /* --- @idle@ --- * | |
613 | * | |
614 | * Arguments: @struct timeval *tv@ = pointer to the current time | |
615 | * @void *vp@ = pointer to a server block | |
616 | * | |
617 | * Returns: --- | |
618 | * | |
619 | * Use: Kills off a child which has been idle for too long. | |
620 | */ | |
621 | ||
622 | static void idle(struct timeval *tv, void *vp) | |
623 | { | |
624 | bres_server *rs = vp; | |
625 | zap(rs); | |
626 | } | |
627 | ||
628 | /* --- @answer@ --- * | |
629 | * | |
630 | * Arguments: @int fd@ = file descriptor which is ready | |
631 | * @unsigned mode@ = what it's doing now | |
632 | * @void *vp@ = pointer to server block | |
633 | * | |
634 | * Returns: --- | |
635 | * | |
636 | * Use: Retrieves an answer from a name resolver process. | |
637 | */ | |
638 | ||
639 | static void attach(bres_client */*rc*/); | |
640 | ||
641 | static void answer(int fd, unsigned mode, void *vp) | |
642 | { | |
643 | bres_server *rs = vp; | |
644 | bres_client *rc = rs->rc; | |
645 | struct hostent *h = 0; | |
646 | int resp; | |
647 | int fail = 1; | |
648 | ||
649 | /* --- Report the result to my client --- */ | |
650 | ||
651 | sel_rmfile(&rs->f); | |
652 | h_errno = -1; | |
653 | if (doread(fd, &resp, sizeof(resp)) == 0) { | |
654 | switch (resp) { | |
655 | case BRES_ERROR: | |
656 | doread(fd, &h_errno, sizeof(h_errno)); | |
657 | fail = 0; | |
658 | break; | |
659 | case BRES_HOSTENT: | |
660 | h = gethost(fd); | |
661 | fail = 0; | |
662 | break; | |
663 | } | |
664 | } | |
665 | if (rc) { | |
666 | rc->func(h, rc->p); | |
667 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 668 | xfree(rc->u.name); |
a759efa6 | 669 | } |
670 | if (h) | |
d8fe3fc2 | 671 | free(h); |
a759efa6 | 672 | if (fail) |
673 | zap(rs); | |
674 | if (!rc) | |
675 | return; | |
676 | ||
677 | /* --- Wrap up the various structures --- */ | |
678 | ||
679 | rs->rc = 0; | |
680 | rc->rs = 0; | |
681 | rs->next = FREE->next; | |
682 | rs->prev = FREE; | |
683 | FREE->next->prev = rs; | |
684 | FREE->next = rs; | |
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 | ||
698 | if (QUEUE->next != QUEUE) { | |
699 | rc = QUEUE->next; | |
700 | QUEUE->next = rc->next; | |
701 | rc->next->prev = QUEUE; | |
702 | attach(rc); | |
703 | } | |
704 | } | |
705 | ||
706 | /* --- @start@ --- * | |
707 | * | |
708 | * Arguments: @bres_server *rs@ = pointer to a server block | |
709 | * | |
710 | * Returns: Zero if OK, nonzero if something failed. | |
711 | * | |
712 | * Use: Starts up a child resolver process. | |
713 | */ | |
714 | ||
715 | static int start(bres_server *rs) | |
716 | { | |
717 | int rfd[2], cfd[2]; | |
718 | pid_t kid; | |
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) { | |
736 | dup2(cfd[0], STDIN_FILENO); | |
737 | dup2(rfd[1], STDOUT_FILENO); | |
738 | close(cfd[0]); | |
739 | close(rfd[1]); | |
740 | execlp(server, server, (char *)0); | |
741 | child(STDOUT_FILENO, STDIN_FILENO); | |
742 | } else | |
743 | child(rfd[1], cfd[0]); | |
744 | _exit(1); | |
745 | } | |
746 | ||
747 | /* --- Fix up everything in the server block --- */ | |
748 | ||
749 | close(cfd[0]); | |
750 | close(rfd[1]); | |
751 | rs->fd = cfd[1]; | |
752 | sel_initfile(sel, &rs->f, rfd[0], SEL_READ, answer, rs); | |
753 | rs->kid = kid; | |
754 | return (0); | |
755 | ||
756 | /* --- Fix up after errors --- */ | |
757 | ||
758 | fail_2: | |
759 | close(cfd[0]); | |
760 | close(cfd[1]); | |
761 | fail_1: | |
762 | close(rfd[0]); | |
763 | close(rfd[1]); | |
764 | fail_0: | |
765 | return (-1); | |
766 | } | |
767 | ||
768 | /* --- @attach@ --- * | |
769 | * | |
770 | * Arguments: @bres_client *rc@ = pointer to a client block | |
771 | * | |
772 | * Returns: --- | |
773 | * | |
774 | * Use: Attaches a client to a spare server (which is assumed to | |
775 | * exist). | |
776 | */ | |
777 | ||
778 | static void attach(bres_client *rc) | |
779 | { | |
780 | bres_server *rs; | |
781 | int lose = 0; | |
782 | ||
783 | /* --- Fix up the server ready for the job --- * | |
784 | * | |
785 | * If the server has a process, remove its timer. Otherwise, fork off a | |
786 | * new resolver process. This is also where I go if I find that the child | |
787 | * resolver process has lost while I wasn't looking. Only one attempt at | |
788 | * forking is performed. | |
789 | */ | |
790 | ||
791 | again: | |
792 | rs = FREE->next; | |
793 | if (rs->kid != -1) | |
794 | sel_rmtimer(&rs->t); | |
795 | else { | |
796 | if (lose || start(rs)) | |
797 | goto lost; | |
798 | lose = 1; | |
799 | } | |
800 | ||
801 | /* --- Submit the job to the resolver --- */ | |
802 | ||
803 | { | |
804 | struct sigaction sa, osa; | |
805 | int e; | |
806 | ||
807 | /* --- Ignore @SIGPIPE@ for now --- * | |
808 | * | |
809 | * This way I can trap @EPIPE@ and reap a losing child, if there was one. | |
810 | */ | |
811 | ||
812 | sa.sa_handler = SIG_IGN; | |
813 | sa.sa_flags = 0; | |
814 | sigemptyset(&sa.sa_mask); | |
815 | sigaction(SIGPIPE, &sa, &osa); | |
816 | ||
817 | /* --- Write the new job to the child --- */ | |
818 | ||
819 | e = 0; | |
820 | if (dowrite(rs->fd, &rc->q, sizeof(rc->q))) | |
821 | e = errno; | |
822 | else switch (rc->q) { | |
823 | case BRES_BYADDR: | |
824 | if (dowrite(rs->fd, &rc->u.addr, sizeof(rc->u.addr))) | |
825 | e = errno; | |
826 | break; | |
827 | case BRES_BYNAME: | |
828 | if (putstring(rs->fd, rc->u.name)) | |
829 | e = errno; | |
830 | break; | |
831 | } | |
832 | sigaction(SIGPIPE, &osa, 0); | |
833 | ||
834 | /* --- Sort out various errors --- * | |
835 | * | |
836 | * This was once more complicated, handling @EPIPE@ separately from other | |
837 | * errors. Now everything's handled the same way. | |
838 | */ | |
839 | ||
840 | if (e) { | |
841 | zap(rs); | |
842 | goto again; | |
843 | } | |
844 | } | |
845 | ||
846 | /* --- Fiddle with lists so that everything's OK --- */ | |
847 | ||
848 | sel_addfile(&rs->f); | |
849 | rs->next->prev = FREE; | |
850 | FREE->next = rs->next; | |
851 | rs->next = rs->prev = rs; | |
852 | rs->rc = rc; | |
853 | rc->rs = rs; | |
854 | return; | |
855 | ||
856 | lost: | |
857 | rc->func(0, rc->p); | |
858 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 859 | xfree(rc->u.name); |
a759efa6 | 860 | } |
861 | ||
862 | /* --- @resolve@ --- * | |
863 | * | |
864 | * Arguments: @bres_client *rc@ = pointer to filled-in client block | |
865 | * | |
866 | * Returns: --- | |
867 | * | |
868 | * Use: Dispatcher for incoming resolution jobs. | |
869 | */ | |
870 | ||
871 | static void resolve(bres_client *rc) | |
872 | { | |
873 | /* --- If there's a free server, plug it in --- */ | |
874 | ||
875 | rc->rs = 0; | |
876 | if (FREE->next == FREE) { | |
877 | rc->next = QUEUE; | |
878 | rc->prev = QUEUE->prev; | |
879 | QUEUE->prev->next = rc; | |
880 | QUEUE->prev = rc; | |
881 | } else | |
882 | attach(rc); | |
883 | } | |
884 | ||
885 | /* --- @bres_byaddr@ --- * | |
886 | * | |
887 | * Arguments: @bres_client *rc@ = pointer to client block | |
888 | * @struct in_addr addr@ = address to resolve | |
889 | * @void (*func)(struct hostent *h, void *p)@ = handler function | |
890 | * @void *p@ = argument for handler function | |
891 | * | |
892 | * Returns: --- | |
893 | * | |
894 | * Use: Adds an address lookup job to the queue. The job will be | |
895 | * processed when there's a spare resolver process to deal with | |
896 | * it. | |
897 | */ | |
898 | ||
899 | void bres_byaddr(bres_client *rc, struct in_addr addr, | |
900 | void (*func)(struct hostent */*h*/, void */*p*/), | |
901 | void *p) | |
902 | { | |
903 | rc->q = BRES_BYADDR; | |
904 | rc->u.addr = addr; | |
905 | rc->func = func; | |
906 | rc->p = p; | |
907 | resolve(rc); | |
908 | } | |
909 | ||
910 | /* --- @bres_byname@ --- * | |
911 | * | |
912 | * Arguments: @bres_client *rc@ = pointer to client block | |
913 | * @const char *name@ = name to resolve | |
914 | * @void (*func)(struct hostent *h, void *p)@ = handler function | |
915 | * @void *p@ = argument for handler function | |
916 | * | |
917 | * Returns: --- | |
918 | * | |
919 | * Use: Adds a name lookup job to the queue. The job will be | |
920 | * processed when there's a spare resolver process to deal with | |
921 | * it. | |
922 | */ | |
923 | ||
924 | void bres_byname(bres_client *rc, const char *name, | |
925 | void (*func)(struct hostent */*h*/, void */*p*/), | |
926 | void *p) | |
927 | { | |
928 | rc->q = BRES_BYNAME; | |
929 | rc->u.name = xstrdup(name); | |
930 | rc->func = func; | |
931 | rc->p = p; | |
932 | resolve(rc); | |
933 | } | |
934 | ||
935 | /* --- @bres_exec@ --- * | |
936 | * | |
937 | * Arguments: @const char *file@ = file containing server code or null | |
938 | * | |
939 | * Returns: --- | |
940 | * | |
941 | * Use: Makes `bres' use a standalone server rather than copies of | |
942 | * the current process. This can reduce memory consumption for | |
943 | * large processes, at the expense of startup time (which | |
944 | * shouldn't be too bad anyway, because of the resolver design). | |
945 | * If the filename is null, a default set up at install time is | |
946 | * used. It's probably a good idea to leave it alone. | |
947 | */ | |
948 | ||
949 | void bres_exec(const char *file) | |
950 | { | |
951 | if (file) | |
952 | server = file; | |
953 | else | |
954 | server = BRES_SERVER; | |
955 | } | |
956 | ||
957 | /* --- @bres_init@ --- * | |
958 | * | |
959 | * Arguments: @sel_state *s@ = pointer to select multiplexor | |
960 | * | |
961 | * Returns: --- | |
962 | * | |
963 | * Use: Initializes the background resolver for use. | |
964 | */ | |
965 | ||
966 | void bres_init(sel_state *s) | |
967 | { | |
968 | int i; | |
969 | ||
970 | sel = s; | |
971 | for (i = 0; i < BRES_MAX; i++) { | |
972 | servers[i].next = FREE; | |
973 | servers[i].prev = FREE->prev; | |
974 | servers[i].kid = -1; | |
975 | servers[i].rc = 0; | |
976 | FREE->prev->next = &servers[i]; | |
977 | FREE->prev = &servers[i]; | |
978 | } | |
979 | } | |
980 | ||
981 | #endif | |
982 | ||
983 | /*----- That's all, folks -------------------------------------------------*/ |