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[mLib] / bres-adns.c
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14d7100d 1/* -*-c-*-
2 *
1dc93196 3 * $Id$
14d7100d 4 *
5 * Background reverse name resolution (ADNS version)
6 *
7 * (c) 2003 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
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.
18 *
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.
23 *
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 *
30 * HOWEVER, since GNU adns is covered by the full GNU General Public
31 * License, this file (only) is also covered by the full GNU GPL, and
32 * you may NOT take advantage of the more liberal conditions of the
33 * LGPL when modifying or redistributing this file. This doesn't mean
34 * that a program which uses the interface provided by this file is
35 * covered by the GPL, since @bres.c@ provides the same interface and
36 * is LGPL. However, it does mean that if your program depends, for
37 * some reason (e.g., to meet particular performance criteria), on
38 * this adns-based implementation of mLib's background resolver then it
39 * must be licensed under the full GPL.
40 */
41
14d7100d 42#ifndef HAVE_ADNS
43# error "You need the ADNS library to compile this file."
44#endif
45
46/*----- Header files ------------------------------------------------------*/
47
48#include <assert.h>
49#include <errno.h>
50#include <signal.h>
51#include <stdio.h>
52#include <stdlib.h>
53#include <string.h>
54
55#include <sys/types.h>
56#include <sys/time.h>
57#include <unistd.h>
58#include <sys/wait.h>
59
60#include <sys/socket.h>
61#include <netinet/in.h>
62#include <arpa/inet.h>
63#include <netdb.h>
64
65#include <adns.h>
66
67#include "alloc.h"
68#include "bres.h"
69#include "macros.h"
70#include "report.h"
71#include "sel.h"
72
73/*----- Static variables --------------------------------------------------*/
74
75static adns_state ads;
76static sel_state *sel;
77static sel_hook selhook;
78
79/*----- Main code ---------------------------------------------------------*/
80
81/* --- @bres_abort@ --- *
82 *
83 * Arguments: @bres_client *rc@ = pointer to client block
84 *
85 * Returns: ---
86 *
87 * Use: Removes a queued job.
88 */
89
90void bres_abort(bres_client *rc)
91{
92 if (rc->q == adns_r_addr) xfree(rc->u.name);
93 if (rc->a) free(rc->a);
94 adns_cancel(rc->aq);
95}
96
97/* --- @bres_byaddr@ --- *
98 *
99 * Arguments: @bres_client *rc@ = pointer to client block
100 * @struct in_addr addr@ = address to resolve
101 * @void (*func)(struct hostent *h, void *p)@ = handler function
102 * @void *p@ = argument for handler function
103 *
104 * Returns: ---
105 *
106 * Use: Adds an address lookup job to the queue. The job will be
107 * processed when there's a spare resolver process to deal with
108 * it.
109 */
110
111void bres_byaddr(bres_client *rc, struct in_addr addr,
112 void (*func)(struct hostent */*h*/, void */*p*/),
113 void *p)
114{
115 int e;
116 struct sockaddr_in sin;
117
118 if (!ads) goto fail;
119 sin.sin_family = AF_INET;
120 sin.sin_addr = addr;
121 sin.sin_port = 0;
122 if ((e = adns_submit_reverse(ads, (struct sockaddr *)&sin, adns_r_ptr,
123 0, rc, &rc->aq)) != 0)
124 goto fail;
125 rc->a = 0;
126 rc->q = adns_r_ptr;
127 rc->u.addr = addr;
128 rc->func = func;
129 rc->p = p;
130 return;
131
132fail:
133 func(0, p);
134}
135
136/* --- @bres_byname@ --- *
137 *
138 * Arguments: @bres_client *rc@ = pointer to client block
139 * @const char *name@ = name to resolve
140 * @void (*func)(struct hostent *h, void *p)@ = handler function
141 * @void *p@ = argument for handler function
142 *
143 * Returns: ---
144 *
145 * Use: Adds a name lookup job to the queue. The job will be
146 * processed when there's a spare resolver process to deal with
147 * it.
148 */
149
150void bres_byname(bres_client *rc, const char *name,
151 void (*func)(struct hostent */*h*/, void */*p*/),
152 void *p)
153{
154 int e;
155
156 if (!ads) goto fail;
157 if ((e = adns_submit(ads, name, adns_r_addr,
4f6d400b 158 adns_qf_search | adns_qf_owner, rc, &rc->aq)) != 0)
14d7100d 159 goto fail;
160 rc->a = 0;
161 rc->q = adns_r_addr;
162 rc->u.name = xstrdup(name);
163 rc->func = func;
164 rc->p = p;
165 return;
166
167fail:
168 func(0, p);
169}
170
171/* --- @bres_exec@ --- *
172 *
173 * Arguments: @const char *file@ = file containing server code or null
174 *
175 * Returns: ---
176 *
177 * Use: Makes `bres' use a standalone server rather than copies of
178 * the current process. This can reduce memory consumption for
179 * large processes, at the expense of startup time (which
180 * shouldn't be too bad anyway, because of the resolver design).
181 * If the filename is null, a default set up at install time is
182 * used. It's probably a good idea to leave it alone.
183 */
184
185void bres_exec(const char *file)
186{
187 /* Nothin' doin' */
188}
189
190/* --- @report@ --- *
191 *
192 * Arguments: @bres_client *c@ = client descriptor block
193 * @adns_answer *a@ = A-record answer from resolver library
194 * @adns_rr_addr *av@ = vector of address records
195 * @int an@ = number of address records (must be positive)
196 * @char **nv@ = vector of name strings
197 * @int nn@ = number of name strings (must be positive)
198 *
199 * Returns: ---
200 *
201 * Use: Formats the given answer into a @struct hostent@ and reports
202 * it to the waiting client application.
203 */
204
205static void report(bres_client *rc, adns_answer *a,
206 adns_rr_addr *av, int an,
207 char **nv, int nn)
208{
209 struct hostent h;
210 char *n[16];
211 char *aa[16];
212 int i, j;
213
214 j = 0;
215 if (a->cname) n[j++] = a->cname;
216 else { n[j++] = *nv; nv++; nn--; }
217 for (i = 0; i < nn && j < N(n) - 1; i++)
218 if (strcmp(n[0], nv[i]) != 0) n[j++] = nv[i];
219 n[j++] = 0;
220 for (i = j = 0; i < an && j < N(av) - 1; i++) {
221 if (av[i].addr.sa.sa_family == AF_INET)
222 aa[j++] = (char *)&av[i].addr.inet.sin_addr;
223 }
224 aa[j++] = 0;
225 h.h_name = n[0];
226 h.h_aliases = n + 1;
227 h.h_addrtype = AF_INET;
228 h.h_length = sizeof(struct in_addr);
229 h.h_addr_list = aa;
230 rc->func(&h, rc->p);
231}
232
233/* --- @beforehook@, @afterhook@ --- *
234 *
235 * Arguments: @sel_state *s@ = select state
236 * @sel_args *sa@ = argument block
237 * @void *p@ = uninteresting pointer
238 *
239 * Returns: ---
240 *
241 * Use: Processes the selector's arguments before @select@ is
242 * called, to allow ADNS to do its thing.
243 */
244
245static void beforehook(sel_state *s, sel_args *sa, void *p)
246{
247 adns_beforeselect(ads, &sa->maxfd,
248 &sa->fd[SEL_READ], &sa->fd[SEL_WRITE], &sa->fd[SEL_EXC],
249 &sa->tvp, &sa->tv, &sa->now);
250}
251
252static void afterhook(sel_state *s, sel_args *sa, void *p)
253{
254 void *c;
255 bres_client *rc;
256 adns_query q;
24a657cc 257 adns_answer *a, *aa;
14d7100d 258 int e;
259 int i;
260
261 adns_afterselect(ads, sa->maxfd,
262 &sa->fd[SEL_READ], &sa->fd[SEL_WRITE], &sa->fd[SEL_EXC],
263 &sa->now);
264 while (q = 0, (e = adns_check(ads, &q, &a, &c)) == 0) {
265 rc = c;
266 if (a->status != 0)
267 goto fail;
268 else switch (rc->q) {
269 case adns_r_addr:
270 assert(a->type == adns_r_addr);
1dc93196 271 xfree(rc->u.name);
24a657cc 272 report(rc, a, a->rrs.addr, a->nrrs, &a->owner, 1);
14d7100d 273 free(a);
274 break;
275 case adns_r_ptr:
276 if (a->type == adns_r_ptr) {
277 rc->a = a;
278 if ((e = adns_submit(ads, a->rrs.str[0], adns_r_addr,
279 0, rc, &q)) != 0)
280 goto fail;
281 rc->aq = q;
282 } else {
283 assert(a->type == adns_r_addr);
284 for (i = 0; i < a->nrrs; i++) {
285 if (a->rrs.addr[i].addr.sa.sa_family == AF_INET &&
286 a->rrs.addr[i].addr.inet.sin_addr.s_addr ==
287 rc->u.addr.s_addr)
288 goto match;
289 }
290 goto fail;
291 match:
24a657cc 292 aa = rc->a;
293 report(rc, a, &a->rrs.addr[i], 1, aa->rrs.str, aa->nrrs);
294 free(aa);
14d7100d 295 free(a);
296 }
297 break;
298 default:
299 abort();
300 }
301 continue;
302
303 fail:
14d7100d 304 if (rc->q == adns_r_addr) xfree(rc->u.name);
305 if (rc->a) free(rc->a);
24a657cc 306 rc->func(0, rc->p);
14d7100d 307 free(a);
308 }
309}
310
311/* --- @bres_init@ --- *
312 *
313 * Arguments: @sel_state *s@ = pointer to select multiplexor
314 *
315 * Returns: ---
316 *
317 * Use: Initializes the background resolver for use.
318 */
319
320void bres_init(sel_state *s)
321{
322 int e;
323
d46d1a2f 324 if ((e = adns_init(&ads, adns_if_noautosys, 0)) != 0) {
14d7100d 325 moan("adns_init failed: resolver won't work");
326 return;
327 }
328 sel_addhook(s, &selhook, beforehook, afterhook, 0);
329 sel = s;
330}
331
332/*----- That's all, folks -------------------------------------------------*/