Commit | Line | Data |
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a759efa6 | 1 | /* -*-c-*- |
2 | * | |
a759efa6 | 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 | ||
65 | #define FREE ((bres_server *)&freelist) | |
66 | static struct { bres_server *next, *prev; } freelist = { FREE, FREE }; | |
67 | ||
68 | #define QUEUE ((bres_client *)&queue) | |
69 | static struct { bres_client *next, *prev; } queue = { QUEUE, QUEUE }; | |
70 | ||
71 | static sel_state *sel; | |
72 | ||
73 | static const char *server = 0; | |
74 | ||
75 | #endif | |
76 | ||
77 | /*----- Background resolver protocol --------------------------------------*/ | |
78 | ||
79 | /* --- Requests and responses --- * | |
80 | * | |
81 | * There are two types of requests: name and addr, corresponding to the | |
82 | * standard @gethostbyname@ and @gethostbyaddr@ calls. There are two types | |
83 | * of responses too: a positive response consists of an encoded equivalent of | |
84 | * a @struct hostent@ structure containing the requested information; a | |
85 | * negative response consists of an @h_errno@ value explaining the problem. | |
86 | */ | |
87 | ||
88 | #define BRES_BYNAME 0 /* Request: resolve given name */ | |
89 | #define BRES_BYADDR 1 /* Request: resolve given address */ | |
90 | ||
91 | #define BRES_HOSTENT 0 /* Response: resolved ok */ | |
92 | #define BRES_ERROR 1 /* Response: resolution failed */ | |
93 | ||
94 | /* --- Encodings --- * | |
95 | * | |
96 | * A string is encoded as a @size_t@ length followed by the actual data. The | |
97 | * null terminator is not transmitted. | |
98 | * | |
99 | * Addresses for resolution are transmitted as raw @struct in_addr@ | |
100 | * structures. | |
101 | * | |
102 | * A @hostent@ structure is transmitted as a header containing fixed-size | |
103 | * information, followed by the official name, an array of aliases, and an | |
104 | * array of addresses. The number of items in the arrays is specified in the | |
105 | * header. | |
106 | * | |
107 | * The implementation assumes that a complete request or reply is always | |
108 | * sent. Undesirable blocking will occur if this is not the case. Both ends | |
109 | * are assumed to trust each other. A protocol failure results in the child | |
110 | * in question being terminated. | |
111 | */ | |
112 | ||
113 | typedef struct hostskel { | |
114 | size_t nalias; | |
115 | int addrtype; | |
116 | size_t addrsz; | |
117 | size_t naddr; | |
118 | } hostskel; | |
119 | ||
120 | /* --- @doread@, @dowrite@ --- * | |
121 | * | |
122 | * Arguments: @int fd@ = file descriptor | |
123 | * @void *buf@ = buffer for data | |
124 | * @size_t sz@ = size of data | |
125 | * | |
126 | * Returns: Zero if successful, nonzero otherwise. | |
127 | * | |
128 | * Use: Reads or writes a chunk of data. @EINTR@ errors are retried; | |
129 | * incomplete reads and writes are continued from where they | |
130 | * left off. End-of-file is considered an I/O error. | |
131 | */ | |
132 | ||
133 | static int doread(int fd, void *buf, size_t sz) | |
134 | { | |
135 | char *p = buf; | |
136 | while (sz) { | |
137 | int r = read(fd, p, sz); | |
138 | if (r < 0) { | |
139 | if (errno == EINTR) | |
140 | continue; | |
141 | return (-1); | |
142 | } else if (r == 0) { | |
143 | errno = EIO; | |
144 | return (-1); | |
145 | } | |
146 | sz -= r; | |
147 | p += r; | |
148 | } | |
149 | return (0); | |
150 | } | |
151 | ||
152 | static int dowrite(int fd, const void *buf, size_t sz) | |
153 | { | |
154 | const char *p = buf; | |
155 | while (sz) { | |
156 | int r = write(fd, p, sz); | |
157 | if (r < 0) { | |
158 | if (errno == EINTR) | |
159 | continue; | |
160 | return (-1); | |
161 | } else if (r == 0) { | |
162 | errno = EIO; | |
163 | return (-1); | |
164 | } | |
165 | sz -= r; | |
166 | p += r; | |
167 | } | |
168 | return (0); | |
169 | } | |
170 | ||
171 | /* --- @getstring@ --- * | |
172 | * | |
173 | * Arguments: @int fd@ = file descriptor to read | |
174 | * | |
175 | * Returns: String in heap-allocated block, or a null pointer. | |
176 | * | |
177 | * Use: Decodes a string. | |
178 | */ | |
179 | ||
180 | static char *getstring(int fd) | |
181 | { | |
182 | size_t sz; | |
183 | char *p; | |
184 | ||
185 | if (doread(fd, &sz, sizeof(sz)) || (p = malloc(sz + 1)) == 0) | |
186 | return (0); | |
187 | if (doread(fd, p, sz)) { | |
188 | free(p); | |
189 | return (0); | |
190 | } | |
191 | p[sz] = 0; | |
192 | return (p); | |
193 | } | |
194 | ||
195 | /* --- @putstring@ --- * | |
196 | * | |
197 | * Arguments: @int fd@ = file descriptor to write on | |
198 | * @const char *p@ = pointer to string to write | |
199 | * | |
200 | * Returns: Zero if successful. | |
201 | * | |
202 | * Use: Encodes a string. | |
203 | */ | |
204 | ||
205 | static int putstring(int fd, const char *p) | |
206 | { | |
207 | size_t sz = strlen(p); | |
208 | if (dowrite(fd, &sz, sizeof(sz)) || dowrite(fd, p, sz)) | |
209 | return (-1); | |
210 | return (0); | |
211 | } | |
212 | ||
213 | /* --- @gethost@ --- * | |
214 | * | |
215 | * Arguments: @int fd@ = file descriptor to read | |
216 | * | |
217 | * Returns: Pointer to heap-allocated @struct hostent@, or null. | |
218 | * | |
219 | * Use: Decodes a host structure. The resulting structure is all in | |
220 | * one big heap block. | |
221 | */ | |
222 | ||
223 | #ifndef BRES_STANDALONE | |
224 | ||
225 | static struct hostent *gethost(int fd) | |
226 | { | |
227 | hostskel hsk; | |
228 | struct hostent *h; | |
229 | char *name; | |
230 | char **alias = 0; | |
d4efbcd9 | 231 | |
a759efa6 | 232 | /* --- Read the skeleton structure --- */ |
233 | ||
234 | if (doread(fd, &hsk, sizeof(hsk))) | |
235 | goto tidy_0; | |
236 | ||
237 | /* --- Read the hostname and alias strings --- * | |
238 | * | |
239 | * Count the length of the strings as we go. | |
240 | */ | |
241 | ||
242 | { | |
243 | size_t sz = | |
244 | sizeof(struct hostent) + | |
245 | hsk.naddr * hsk.addrsz + | |
246 | (hsk.naddr + hsk.nalias + 2) * sizeof(char *); | |
247 | ||
248 | /* --- Read the primary host name --- */ | |
249 | ||
250 | if ((name = getstring(fd)) == 0) | |
251 | goto tidy_0; | |
252 | sz += strlen(name) + 1; | |
253 | ||
254 | /* --- Read in the alias names --- */ | |
255 | ||
256 | if (hsk.nalias) { | |
257 | int i; | |
258 | if ((alias = malloc(hsk.nalias * sizeof(char *))) == 0) | |
d4efbcd9 | 259 | goto tidy_1; |
a759efa6 | 260 | for (i = 0; i < hsk.nalias; i++) |
261 | alias[i] = 0; | |
262 | for (i = 0; i < hsk.nalias; i++) { | |
263 | if ((alias[i] = getstring(fd)) == 0) | |
264 | goto tidy_2; | |
265 | sz += strlen(alias[i]) + 1; | |
266 | } | |
267 | } | |
268 | ||
269 | /* --- Allocate the output structure --- */ | |
270 | ||
271 | if ((h = malloc(sz)) == 0) | |
272 | goto tidy_2; | |
273 | } | |
274 | ||
275 | /* --- Fill in the base structure --- */ | |
276 | ||
277 | h->h_addrtype = hsk.addrtype; | |
278 | h->h_length = hsk.addrsz; | |
279 | ||
280 | /* --- Start putting everything else in --- */ | |
281 | ||
282 | { | |
283 | char **p = (char **)(h + 1); | |
284 | char *a = (char *)(p + hsk.nalias + hsk.naddr + 2); | |
285 | int i; | |
286 | ||
287 | /* --- Start with the address table --- */ | |
288 | ||
289 | h->h_addr_list = p; | |
290 | if (doread(fd, a, hsk.naddr * hsk.addrsz)) | |
291 | goto tidy_2; | |
292 | for (i = 0; i < hsk.naddr; i++) { | |
a759efa6 | 293 | *p++ = a; |
364308dc | 294 | a += hsk.addrsz; |
a759efa6 | 295 | } |
296 | *p++ = 0; | |
297 | ||
298 | /* --- Finally copy the strings over --- */ | |
299 | ||
300 | #define PUT(_p) do { \ | |
301 | size_t _len = strlen(_p) + 1; \ | |
302 | memcpy(a, (_p), _len); \ | |
303 | a += _len; \ | |
304 | } while (0) | |
305 | ||
306 | h->h_name = a; | |
307 | PUT(name); | |
d8fe3fc2 | 308 | free(name); |
a759efa6 | 309 | h->h_aliases = p; |
310 | for (i = 0; i < hsk.nalias; i++) { | |
311 | *p++ = a; | |
312 | PUT(alias[i]); | |
d8fe3fc2 | 313 | free(alias[i]); |
a759efa6 | 314 | } |
315 | *p++ = 0; | |
d8fe3fc2 | 316 | free(alias); |
d4efbcd9 | 317 | |
a759efa6 | 318 | #undef PUT |
319 | } | |
320 | ||
321 | return (h); | |
322 | ||
323 | /* --- Tidy up after various types of failure --- */ | |
324 | ||
325 | tidy_2: | |
326 | { | |
327 | int i; | |
328 | for (i = 0; i < hsk.nalias && alias[i]; i++) | |
d8fe3fc2 | 329 | free(alias[i]); |
330 | free(alias); | |
a759efa6 | 331 | } |
332 | tidy_1: | |
d8fe3fc2 | 333 | free(name); |
a759efa6 | 334 | tidy_0: |
335 | return (0); | |
336 | } | |
337 | ||
338 | #endif | |
339 | ||
340 | /* --- @puthost@ --- * | |
341 | * | |
342 | * Arguments: @int fd@ = file descriptor | |
343 | * @struct hostent *h@ = pointer to host structure | |
344 | * | |
345 | * Returns: Zero if successful. | |
346 | * | |
347 | * Use: Encodes a host structure. | |
348 | */ | |
349 | ||
350 | static int puthost(int fd, struct hostent *h) | |
351 | { | |
352 | hostskel hsk; | |
353 | int i; | |
354 | ||
355 | /* --- Fill in and send the skeleton structure --- */ | |
356 | ||
357 | for (i = 0; h->h_aliases[i]; i++) | |
358 | ; | |
359 | hsk.nalias = i; | |
360 | for (i = 0; h->h_addr_list[i]; i++) | |
361 | ; | |
362 | hsk.naddr = i; | |
363 | hsk.addrtype = h->h_addrtype; | |
364 | hsk.addrsz = h->h_length; | |
365 | if (dowrite(fd, &hsk, sizeof(hsk))) | |
366 | return (-1); | |
367 | ||
368 | /* --- Send the name and alias strings --- */ | |
369 | ||
370 | if (putstring(fd, h->h_name)) | |
371 | return (-1); | |
372 | for (i = 0; h->h_aliases[i]; i++) { | |
373 | if (putstring(fd, h->h_aliases[i])) | |
374 | return (-1); | |
375 | } | |
376 | ||
377 | /* --- Send the address data --- */ | |
378 | ||
379 | for (i = 0; h->h_addr_list[i]; i++) { | |
380 | if (dowrite(fd, h->h_addr_list[i], hsk.addrsz)) | |
381 | return (-1); | |
382 | } | |
383 | ||
384 | /* --- OK, done --- */ | |
385 | ||
386 | return (0); | |
387 | } | |
388 | ||
389 | /*----- Resolver server ---------------------------------------------------*/ | |
390 | ||
391 | /* --- @child@ --- * | |
392 | * | |
393 | * Arguments: @int rfd@ = output file descriptor for resolved hostnames | |
394 | * @int cfd@ = input file descriptor for raw addresses | |
395 | * | |
396 | * Returns: Never. | |
397 | * | |
398 | * Use: Asynchronous name resolving process. | |
399 | */ | |
400 | ||
401 | static void child(int rfd, int cfd) | |
402 | { | |
403 | /* --- Close other file descriptors --- */ | |
404 | ||
405 | { | |
406 | int i; | |
5d6d2d94 | 407 | #if defined(_SC_OPEN_MAX) |
a759efa6 | 408 | int maxfd = sysconf(_SC_OPEN_MAX); |
5d6d2d94 | 409 | #elif defined(OPEN_MAX) |
410 | int maxfd = OPEN_MAX; | |
411 | #else | |
412 | int maxfd = -1; | |
413 | #endif | |
a759efa6 | 414 | |
415 | if (maxfd < 0) | |
416 | maxfd = 256; /* Fingers crossed... */ | |
417 | for (i = 0; i < maxfd; i++) { | |
418 | if (i != rfd && i != cfd && i != 1) | |
419 | close(i); | |
420 | } | |
421 | } | |
422 | ||
364308dc | 423 | signal(SIGTERM, SIG_DFL); |
424 | signal(SIGHUP, SIG_DFL); | |
425 | signal(SIGQUIT, SIG_DFL); | |
426 | signal(SIGALRM, SIG_DFL); | |
427 | signal(SIGINT, SIG_DFL); | |
428 | ||
a759efa6 | 429 | /* --- Main request/response loop --- */ |
430 | ||
431 | for (;;) { | |
432 | int req, resp; | |
433 | struct hostent *h; | |
434 | ||
435 | /* --- Read the request --- */ | |
436 | ||
437 | if (doread(cfd, &req, sizeof(req))) | |
438 | goto lose; | |
439 | ||
440 | /* --- Process it into a host structure --- */ | |
441 | ||
442 | switch (req) { | |
443 | ||
444 | /* --- Normal forward lookup --- */ | |
445 | ||
446 | case BRES_BYNAME: { | |
447 | char *name = getstring(cfd); | |
448 | if (!name) | |
449 | goto lose; | |
450 | h = gethostbyname(name); | |
451 | free(name); | |
452 | } break; | |
453 | ||
d8fe3fc2 | 454 | /* --- Reverse lookup --- */ |
a759efa6 | 455 | |
456 | case BRES_BYADDR: { | |
457 | struct in_addr addr; | |
458 | char *p; | |
459 | if (doread(cfd, &addr, sizeof(addr))) | |
460 | goto lose; | |
461 | if ((h = gethostbyaddr((char *)&addr, sizeof(addr), AF_INET)) == 0) | |
462 | goto fail; | |
463 | ||
464 | /* --- Do a forward lookup to confirm --- */ | |
465 | ||
466 | { | |
467 | size_t sz = strlen(h->h_name) + 1; | |
468 | if ((p = malloc(sz)) == 0) | |
469 | goto fail; | |
470 | memcpy(p, h->h_name, sz); | |
471 | } | |
472 | ||
473 | h = gethostbyname(p); | |
474 | free(p); | |
475 | if (!h) | |
476 | goto fail; | |
477 | p = 0; | |
478 | if (h) { | |
479 | char **pp; | |
480 | for (pp = h->h_addr_list; *pp; pp++) { | |
481 | struct in_addr a; | |
482 | memcpy(&a, *pp, sizeof(a)); | |
483 | if (a.s_addr == addr.s_addr) { | |
484 | p = h->h_name; | |
485 | break; | |
486 | } | |
487 | } | |
488 | } | |
489 | if (!p) { | |
490 | h = 0; | |
491 | h_errno = NO_RECOVERY; | |
492 | } | |
493 | fail:; | |
494 | } break; | |
495 | ||
496 | /* --- Unknown request -- may have lost sync --- */ | |
497 | ||
498 | default: | |
499 | goto lose; | |
500 | } | |
501 | ||
502 | /* --- Transmit the response --- */ | |
503 | ||
504 | if (h) { | |
505 | resp = BRES_HOSTENT; | |
506 | if (dowrite(rfd, &resp, sizeof(resp)) || puthost(rfd, h)) | |
507 | goto lose; | |
508 | } else { | |
509 | resp = BRES_ERROR; | |
510 | if (dowrite(rfd, &resp, sizeof(resp)) || | |
511 | dowrite(rfd, &h_errno, sizeof(h_errno))) | |
512 | goto lose; | |
513 | } | |
514 | } | |
515 | ||
516 | lose: | |
517 | _exit(1); | |
518 | } | |
519 | ||
520 | /* --- @main@ --- * | |
521 | * | |
522 | * Arguments: @int argc@ = number of command line arguments | |
523 | * @char *argv[]@ = array of arguments | |
524 | * | |
525 | * Returns: Runs until killed or an error occurs. | |
526 | * | |
527 | * Use: A name resolver server process for mLib programs which need | |
528 | * this sort of thing. | |
529 | */ | |
530 | ||
531 | #ifdef BRES_STANDALONE | |
532 | ||
533 | int main(int argc, char *argv[]) | |
534 | { | |
535 | if (isatty(STDIN_FILENO)) { | |
536 | char *p = strrchr(argv[0], '/'); | |
537 | if (p) | |
538 | p++; | |
539 | else | |
540 | p = argv[0]; | |
541 | fprintf(stderr, | |
542 | "%s: don't run this program unless you know what you're doing.\n", | |
543 | p); | |
544 | exit(1); | |
545 | } | |
546 | child(STDOUT_FILENO, STDIN_FILENO); | |
547 | return (1); | |
548 | } | |
549 | ||
550 | #endif | |
551 | ||
552 | /*----- Main code ---------------------------------------------------------*/ | |
553 | ||
554 | #ifndef BRES_STANDALONE | |
555 | ||
556 | /* --- @zap@ --- * | |
557 | * | |
558 | * Arguments: @bres_server *rs@ = pointer to server block | |
559 | * | |
560 | * Returns: --- | |
561 | * | |
562 | * Use: Kills a server process, reaps the losing child and makes | |
563 | * things generally clean again. | |
564 | */ | |
565 | ||
566 | static void zap(bres_server *rs) | |
567 | { | |
568 | /* --- Close the pipes, kill the child, and reap it --- */ | |
569 | ||
570 | if (rs->kid != -1) { | |
571 | close(rs->fd); | |
572 | close(rs->f.fd); | |
573 | kill(rs->kid, SIGTERM); | |
574 | waitpid(rs->kid, 0, 0); | |
575 | rs->kid = -1; | |
576 | } | |
577 | ||
578 | /* --- Move the server to the back of the list --- */ | |
579 | ||
580 | rs->next->prev = rs->prev; | |
581 | rs->prev->next = rs->next; | |
582 | rs->next = FREE; | |
583 | rs->prev = FREE->prev; | |
584 | FREE->prev->next = rs; | |
585 | FREE->prev = rs; | |
586 | } | |
587 | ||
588 | /* --- @bres_abort@ --- * | |
589 | * | |
590 | * Arguments: @bres_client *rc@ = pointer to client block | |
591 | * | |
592 | * Returns: --- | |
593 | * | |
594 | * Use: Removes a queued job. | |
595 | */ | |
596 | ||
597 | void bres_abort(bres_client *rc) | |
598 | { | |
599 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 600 | xfree(rc->u.name); |
a759efa6 | 601 | if (rc->rs) { |
602 | sel_rmfile(&rc->rs->f); | |
603 | zap(rc->rs); | |
604 | rc->rs = 0; | |
605 | } else { | |
606 | rc->next->prev = rc->prev; | |
607 | rc->prev->next = rc->next; | |
608 | } | |
609 | } | |
610 | ||
611 | /* --- @idle@ --- * | |
612 | * | |
613 | * Arguments: @struct timeval *tv@ = pointer to the current time | |
614 | * @void *vp@ = pointer to a server block | |
615 | * | |
616 | * Returns: --- | |
617 | * | |
618 | * Use: Kills off a child which has been idle for too long. | |
619 | */ | |
620 | ||
621 | static void idle(struct timeval *tv, void *vp) | |
622 | { | |
623 | bres_server *rs = vp; | |
624 | zap(rs); | |
625 | } | |
626 | ||
627 | /* --- @answer@ --- * | |
628 | * | |
629 | * Arguments: @int fd@ = file descriptor which is ready | |
630 | * @unsigned mode@ = what it's doing now | |
631 | * @void *vp@ = pointer to server block | |
632 | * | |
633 | * Returns: --- | |
634 | * | |
635 | * Use: Retrieves an answer from a name resolver process. | |
636 | */ | |
637 | ||
638 | static void attach(bres_client */*rc*/); | |
639 | ||
640 | static void answer(int fd, unsigned mode, void *vp) | |
641 | { | |
642 | bres_server *rs = vp; | |
643 | bres_client *rc = rs->rc; | |
644 | struct hostent *h = 0; | |
645 | int resp; | |
646 | int fail = 1; | |
647 | ||
648 | /* --- Report the result to my client --- */ | |
649 | ||
650 | sel_rmfile(&rs->f); | |
651 | h_errno = -1; | |
652 | if (doread(fd, &resp, sizeof(resp)) == 0) { | |
653 | switch (resp) { | |
654 | case BRES_ERROR: | |
655 | doread(fd, &h_errno, sizeof(h_errno)); | |
656 | fail = 0; | |
657 | break; | |
658 | case BRES_HOSTENT: | |
659 | h = gethost(fd); | |
660 | fail = 0; | |
661 | break; | |
662 | } | |
663 | } | |
664 | if (rc) { | |
665 | rc->func(h, rc->p); | |
666 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 667 | xfree(rc->u.name); |
a759efa6 | 668 | } |
669 | if (h) | |
d8fe3fc2 | 670 | free(h); |
a759efa6 | 671 | if (fail) |
672 | zap(rs); | |
673 | if (!rc) | |
674 | return; | |
675 | ||
676 | /* --- Wrap up the various structures --- */ | |
677 | ||
678 | rs->rc = 0; | |
679 | rc->rs = 0; | |
680 | rs->next = FREE->next; | |
681 | rs->prev = FREE; | |
682 | FREE->next->prev = rs; | |
683 | FREE->next = rs; | |
684 | ||
685 | /* --- Tie a timer onto the server block --- */ | |
686 | ||
687 | { | |
688 | struct timeval tv; | |
689 | ||
690 | gettimeofday(&tv, 0); | |
691 | tv.tv_sec += BRES_IDLE; | |
692 | sel_addtimer(sel, &rs->t, &tv, idle, rs); | |
693 | } | |
694 | ||
695 | /* --- If there are any clients waiting, attach one --- */ | |
696 | ||
697 | if (QUEUE->next != QUEUE) { | |
698 | rc = QUEUE->next; | |
699 | QUEUE->next = rc->next; | |
700 | rc->next->prev = QUEUE; | |
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: | |
790 | rs = FREE->next; | |
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); | |
847 | rs->next->prev = FREE; | |
848 | FREE->next = rs->next; | |
849 | rs->next = rs->prev = rs; | |
850 | rs->rc = rc; | |
851 | rc->rs = rs; | |
852 | return; | |
853 | ||
854 | lost: | |
855 | rc->func(0, rc->p); | |
856 | if (rc->q == BRES_BYNAME) | |
e2a18bd0 | 857 | xfree(rc->u.name); |
a759efa6 | 858 | } |
859 | ||
860 | /* --- @resolve@ --- * | |
861 | * | |
862 | * Arguments: @bres_client *rc@ = pointer to filled-in client block | |
863 | * | |
864 | * Returns: --- | |
865 | * | |
866 | * Use: Dispatcher for incoming resolution jobs. | |
867 | */ | |
868 | ||
869 | static void resolve(bres_client *rc) | |
870 | { | |
871 | /* --- If there's a free server, plug it in --- */ | |
872 | ||
873 | rc->rs = 0; | |
874 | if (FREE->next == FREE) { | |
875 | rc->next = QUEUE; | |
876 | rc->prev = QUEUE->prev; | |
877 | QUEUE->prev->next = rc; | |
878 | QUEUE->prev = rc; | |
879 | } else | |
880 | attach(rc); | |
881 | } | |
882 | ||
883 | /* --- @bres_byaddr@ --- * | |
884 | * | |
885 | * Arguments: @bres_client *rc@ = pointer to client block | |
886 | * @struct in_addr addr@ = address to resolve | |
887 | * @void (*func)(struct hostent *h, void *p)@ = handler function | |
888 | * @void *p@ = argument for handler function | |
889 | * | |
890 | * Returns: --- | |
891 | * | |
892 | * Use: Adds an address lookup job to the queue. The job will be | |
893 | * processed when there's a spare resolver process to deal with | |
894 | * it. | |
895 | */ | |
896 | ||
897 | void bres_byaddr(bres_client *rc, struct in_addr addr, | |
898 | void (*func)(struct hostent */*h*/, void */*p*/), | |
899 | void *p) | |
900 | { | |
901 | rc->q = BRES_BYADDR; | |
902 | rc->u.addr = addr; | |
903 | rc->func = func; | |
904 | rc->p = p; | |
905 | resolve(rc); | |
906 | } | |
907 | ||
908 | /* --- @bres_byname@ --- * | |
909 | * | |
910 | * Arguments: @bres_client *rc@ = pointer to client block | |
911 | * @const char *name@ = name to resolve | |
912 | * @void (*func)(struct hostent *h, void *p)@ = handler function | |
913 | * @void *p@ = argument for handler function | |
914 | * | |
915 | * Returns: --- | |
916 | * | |
917 | * Use: Adds a name lookup job to the queue. The job will be | |
918 | * processed when there's a spare resolver process to deal with | |
919 | * it. | |
920 | */ | |
921 | ||
922 | void bres_byname(bres_client *rc, const char *name, | |
923 | void (*func)(struct hostent */*h*/, void */*p*/), | |
924 | void *p) | |
925 | { | |
926 | rc->q = BRES_BYNAME; | |
927 | rc->u.name = xstrdup(name); | |
928 | rc->func = func; | |
929 | rc->p = p; | |
930 | resolve(rc); | |
931 | } | |
932 | ||
933 | /* --- @bres_exec@ --- * | |
934 | * | |
935 | * Arguments: @const char *file@ = file containing server code or null | |
936 | * | |
937 | * Returns: --- | |
938 | * | |
939 | * Use: Makes `bres' use a standalone server rather than copies of | |
940 | * the current process. This can reduce memory consumption for | |
941 | * large processes, at the expense of startup time (which | |
942 | * shouldn't be too bad anyway, because of the resolver design). | |
943 | * If the filename is null, a default set up at install time is | |
944 | * used. It's probably a good idea to leave it alone. | |
945 | */ | |
946 | ||
947 | void bres_exec(const char *file) | |
948 | { | |
949 | if (file) | |
950 | server = file; | |
951 | else | |
952 | server = BRES_SERVER; | |
953 | } | |
954 | ||
955 | /* --- @bres_init@ --- * | |
956 | * | |
957 | * Arguments: @sel_state *s@ = pointer to select multiplexor | |
958 | * | |
959 | * Returns: --- | |
960 | * | |
961 | * Use: Initializes the background resolver for use. | |
962 | */ | |
963 | ||
964 | void bres_init(sel_state *s) | |
965 | { | |
966 | int i; | |
967 | ||
968 | sel = s; | |
969 | for (i = 0; i < BRES_MAX; i++) { | |
970 | servers[i].next = FREE; | |
971 | servers[i].prev = FREE->prev; | |
972 | servers[i].kid = -1; | |
973 | servers[i].rc = 0; | |
974 | FREE->prev->next = &servers[i]; | |
975 | FREE->prev = &servers[i]; | |
976 | } | |
977 | } | |
978 | ||
979 | #endif | |
980 | ||
981 | /*----- That's all, folks -------------------------------------------------*/ |