/[resiprocate]/main/contrib/ares/ares_init.c
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Revision 1479 - (hide annotations) (download)
Thu Jun 5 00:30:30 2003 UTC (16 years, 6 months ago) by ryker
Original Path: main/sip/contrib/ares/ares_init.c
File MIME type: text/plain
File size: 15452 byte(s)
Initial revision

1 ryker 1479 /* Copyright 1998 by the Massachusetts Institute of Technology.
2     *
3     * Permission to use, copy, modify, and distribute this
4     * software and its documentation for any purpose and without
5     * fee is hereby granted, provided that the above copyright
6     * notice appear in all copies and that both that copyright
7     * notice and this permission notice appear in supporting
8     * documentation, and that the name of M.I.T. not be used in
9     * advertising or publicity pertaining to distribution of the
10     * software without specific, written prior permission.
11     * M.I.T. makes no representations about the suitability of
12     * this software for any purpose. It is provided "as is"
13     * without express or implied warranty.
14     */
15    
16     static const char rcsid[] = "$Id: ares_init.c,v 1.1 2003/06/05 00:30:35 ryker Exp $";
17    
18     #include <sys/types.h>
19     #include <sys/time.h>
20     #include <sys/param.h>
21     #include <netinet/in.h>
22     #include <arpa/inet.h>
23     #include <arpa/nameser.h>
24     #include <stdio.h>
25     #include <stdlib.h>
26     #include <string.h>
27     #include <ctype.h>
28     #include <time.h>
29     #include <unistd.h>
30     #include <errno.h>
31     #include <netdb.h>
32     #include "ares.h"
33     #include "ares_private.h"
34    
35     static int init_by_options(ares_channel channel, struct ares_options *options,
36     int optmask);
37     static int init_by_environment(ares_channel channel);
38     static int init_by_resolv_conf(ares_channel channel);
39     static int init_by_defaults(ares_channel channel);
40     static int config_domain(ares_channel channel, char *str);
41     static int config_lookup(ares_channel channel, const char *str);
42     static int config_nameserver(struct server_state **servers, int *nservers,
43     const char *str);
44     static int config_sortlist(struct apattern **sortlist, int *nsort,
45     const char *str);
46     static int set_search(ares_channel channel, const char *str);
47     static int set_options(ares_channel channel, const char *str);
48     static char *try_config(char *s, char *opt);
49     static const char *try_option(const char *p, const char *q, const char *opt);
50     static int ip_addr(const char *s, int len, struct in_addr *addr);
51     static void natural_mask(struct apattern *pat);
52    
53     int ares_init(ares_channel *channelptr)
54     {
55     return ares_init_options(channelptr, NULL, 0);
56     }
57    
58     int ares_init_options(ares_channel *channelptr, struct ares_options *options,
59     int optmask)
60     {
61     ares_channel channel;
62     int i, status;
63     struct server_state *server;
64     struct timeval tv;
65    
66     channel = malloc(sizeof(struct ares_channeldata));
67     if (!channel)
68     return ARES_ENOMEM;
69    
70     /* Set everything to distinguished values so we know they haven't
71     * been set yet.
72     */
73     channel->flags = -1;
74     channel->timeout = -1;
75     channel->tries = -1;
76     channel->ndots = -1;
77     channel->udp_port = -1;
78     channel->tcp_port = -1;
79     channel->nservers = -1;
80     channel->ndomains = -1;
81     channel->nsort = -1;
82     channel->lookups = NULL;
83    
84     /* Initialize configuration by each of the four sources, from highest
85     * precedence to lowest.
86     */
87     status = init_by_options(channel, options, optmask);
88     if (status == ARES_SUCCESS)
89     status = init_by_environment(channel);
90     if (status == ARES_SUCCESS)
91     status = init_by_resolv_conf(channel);
92     if (status == ARES_SUCCESS)
93     status = init_by_defaults(channel);
94     if (status != ARES_SUCCESS)
95     {
96     /* Something failed; clean up memory we may have allocated. */
97     if (channel->nservers != -1)
98     free(channel->servers);
99     if (channel->ndomains != -1)
100     {
101     for (i = 0; i < channel->ndomains; i++)
102     free(channel->domains[i]);
103     free(channel->domains);
104     }
105     if (channel->nsort != -1)
106     free(channel->sortlist);
107     free(channel->lookups);
108     free(channel);
109     return status;
110     }
111    
112     /* Trim to one server if ARES_FLAG_PRIMARY is set. */
113     if ((channel->flags & ARES_FLAG_PRIMARY) && channel->nservers > 1)
114     channel->nservers = 1;
115    
116     /* Initialize server states. */
117     for (i = 0; i < channel->nservers; i++)
118     {
119     server = &channel->servers[i];
120     server->udp_socket = -1;
121     server->tcp_socket = -1;
122     server->tcp_lenbuf_pos = 0;
123     server->tcp_buffer = NULL;
124     server->qhead = NULL;
125     server->qtail = NULL;
126     }
127    
128     /* Choose a somewhat random query ID. The main point is to avoid
129     * collisions with stale queries. An attacker trying to spoof a DNS
130     * answer also has to guess the query ID, but it's only a 16-bit
131     * field, so there's not much to be done about that.
132     */
133     gettimeofday(&tv, NULL);
134     channel->next_id = (tv.tv_sec ^ tv.tv_usec ^ getpid()) & 0xffff;
135    
136     channel->queries = NULL;
137    
138     *channelptr = channel;
139     return ARES_SUCCESS;
140     }
141    
142     static int init_by_options(ares_channel channel, struct ares_options *options,
143     int optmask)
144     {
145     int i;
146    
147     /* Easy stuff. */
148     if ((optmask & ARES_OPT_FLAGS) && channel->flags == -1)
149     channel->flags = options->flags;
150     if ((optmask & ARES_OPT_TIMEOUT) && channel->timeout == -1)
151     channel->timeout = options->timeout;
152     if ((optmask & ARES_OPT_TRIES) && channel->tries == -1)
153     channel->tries = options->tries;
154     if ((optmask & ARES_OPT_NDOTS) && channel->ndots == -1)
155     channel->ndots = options->ndots;
156     if ((optmask & ARES_OPT_UDP_PORT) && channel->udp_port == -1)
157     channel->udp_port = options->udp_port;
158     if ((optmask & ARES_OPT_TCP_PORT) && channel->tcp_port == -1)
159     channel->tcp_port = options->tcp_port;
160    
161     /* Copy the servers, if given. */
162     if ((optmask & ARES_OPT_SERVERS) && channel->nservers == -1)
163     {
164     channel->servers =
165     malloc(options->nservers * sizeof(struct server_state));
166     if (!channel->servers && options->nservers != 0)
167     return ARES_ENOMEM;
168     for (i = 0; i < options->nservers; i++)
169     channel->servers[i].addr = options->servers[i];
170     channel->nservers = options->nservers;
171     }
172    
173     /* Copy the domains, if given. Keep channel->ndomains consistent so
174     * we can clean up in case of error.
175     */
176     if ((optmask & ARES_OPT_DOMAINS) && channel->ndomains == -1)
177     {
178     channel->domains = malloc(options->ndomains * sizeof(char *));
179     if (!channel->domains && options->ndomains != 0)
180     return ARES_ENOMEM;
181     for (i = 0; i < options->ndomains; i++)
182     {
183     channel->ndomains = i;
184     channel->domains[i] = strdup(options->domains[i]);
185     if (!channel->domains[i])
186     return ARES_ENOMEM;
187     }
188     channel->ndomains = options->ndomains;
189     }
190    
191     /* Set lookups, if given. */
192     if ((optmask & ARES_OPT_LOOKUPS) && !channel->lookups)
193     {
194     channel->lookups = strdup(options->lookups);
195     if (!channel->lookups)
196     return ARES_ENOMEM;
197     }
198    
199     return ARES_SUCCESS;
200     }
201    
202     static int init_by_environment(ares_channel channel)
203     {
204     const char *localdomain, *res_options;
205     int status;
206    
207     localdomain = getenv("LOCALDOMAIN");
208     if (localdomain && channel->ndomains == -1)
209     {
210     status = set_search(channel, localdomain);
211     if (status != ARES_SUCCESS)
212     return status;
213     }
214    
215     res_options = getenv("RES_OPTIONS");
216     if (res_options)
217     {
218     status = set_options(channel, res_options);
219     if (status != ARES_SUCCESS)
220     return status;
221     }
222    
223     return ARES_SUCCESS;
224     }
225    
226     static int init_by_resolv_conf(ares_channel channel)
227     {
228     FILE *fp;
229     char *line = NULL, *p;
230     int linesize, status, nservers = 0, nsort = 0;
231     struct server_state *servers = NULL;
232     struct apattern *sortlist = NULL;
233    
234     fp = fopen(PATH_RESOLV_CONF, "r");
235     if (!fp)
236     return (errno == ENOENT) ? ARES_SUCCESS : ARES_EFILE;
237     while ((status = ares__read_line(fp, &line, &linesize)) == ARES_SUCCESS)
238     {
239     if ((p = try_config(line, "domain")) && channel->ndomains == -1)
240     status = config_domain(channel, p);
241     else if ((p = try_config(line, "lookup")) && !channel->lookups)
242     status = config_lookup(channel, p);
243     else if ((p = try_config(line, "search")) && channel->ndomains == -1)
244     status = set_search(channel, p);
245     else if ((p = try_config(line, "nameserver")) && channel->nservers == -1)
246     status = config_nameserver(&servers, &nservers, p);
247     else if ((p = try_config(line, "sortlist")) && channel->nsort == -1)
248     status = config_sortlist(&sortlist, &nsort, p);
249     else if ((p = try_config(line, "options")))
250     status = set_options(channel, p);
251     else
252     status = ARES_SUCCESS;
253     if (status != ARES_SUCCESS)
254     break;
255     }
256     free(line);
257     fclose(fp);
258    
259     /* Handle errors. */
260     if (status != ARES_EOF)
261     {
262     free(servers);
263     free(sortlist);
264     return status;
265     }
266    
267     /* If we got any name server entries, fill them in. */
268     if (servers)
269     {
270     channel->servers = servers;
271     channel->nservers = nservers;
272     }
273    
274     /* If we got any sortlist entries, fill them in. */
275     if (sortlist)
276     {
277     channel->sortlist = sortlist;
278     channel->nsort = nsort;
279     }
280    
281     return ARES_SUCCESS;
282     }
283    
284     static int init_by_defaults(ares_channel channel)
285     {
286     char hostname[MAXHOSTNAMELEN + 1];
287    
288     if (channel->flags == -1)
289     channel->flags = 0;
290     if (channel->timeout == -1)
291     channel->timeout = DEFAULT_TIMEOUT;
292     if (channel->tries == -1)
293     channel->tries = DEFAULT_TRIES;
294     if (channel->ndots == -1)
295     channel->ndots = 1;
296     if (channel->udp_port == -1)
297     channel->udp_port = htons(NAMESERVER_PORT);
298     if (channel->tcp_port == -1)
299     channel->tcp_port = htons(NAMESERVER_PORT);
300    
301     if (channel->nservers == -1)
302     {
303     /* If nobody specified servers, try a local named. */
304     channel->servers = malloc(sizeof(struct server_state));
305     if (!channel->servers)
306     return ARES_ENOMEM;
307     channel->servers[0].addr.s_addr = htonl(INADDR_LOOPBACK);
308     channel->nservers = 1;
309     }
310    
311     if (channel->ndomains == -1)
312     {
313     /* Derive a default domain search list from the kernel hostname,
314     * or set it to empty if the hostname isn't helpful.
315     */
316     if (gethostname(hostname, sizeof(hostname)) == -1
317     || !strchr(hostname, '.'))
318     {
319     channel->domains = malloc(0);
320     channel->ndomains = 0;
321     }
322     else
323     {
324     channel->domains = malloc(sizeof(char *));
325     if (!channel->domains)
326     return ARES_ENOMEM;
327     channel->ndomains = 0;
328     channel->domains[0] = strdup(strchr(hostname, '.') + 1);
329     if (!channel->domains[0])
330     return ARES_ENOMEM;
331     channel->ndomains = 1;
332     }
333     }
334    
335     if (channel->nsort == -1)
336     {
337     channel->sortlist = NULL;
338     channel->nsort = 0;
339     }
340    
341     if (!channel->lookups)
342     {
343     channel->lookups = strdup("bf");
344     if (!channel->lookups)
345     return ARES_ENOMEM;
346     }
347    
348     return ARES_SUCCESS;
349     }
350    
351     static int config_domain(ares_channel channel, char *str)
352     {
353     char *q;
354    
355     /* Set a single search domain. */
356     q = str;
357     while (*q && !isspace((unsigned char)*q))
358     q++;
359     *q = 0;
360     return set_search(channel, str);
361     }
362    
363     static int config_lookup(ares_channel channel, const char *str)
364     {
365     char lookups[3], *l;
366     const char *p;
367    
368     /* Set the lookup order. Only the first letter of each work
369     * is relevant, and it has to be "b" for DNS or "f" for the
370     * host file. Ignore everything else.
371     */
372     l = lookups;
373     p = str;
374     while (*p)
375     {
376     if ((*p == 'b' || *p == 'f') && l < lookups + 2)
377     *l++ = *p;
378     while (*p && !isspace((unsigned char)*p))
379     p++;
380     while (isspace((unsigned char)*p))
381     p++;
382     }
383     *l = 0;
384     channel->lookups = strdup(lookups);
385     return (channel->lookups) ? ARES_SUCCESS : ARES_ENOMEM;
386     }
387    
388     static int config_nameserver(struct server_state **servers, int *nservers,
389     const char *str)
390     {
391     struct in_addr addr;
392     struct server_state *newserv;
393    
394     /* Add a nameserver entry, if this is a valid address. */
395     addr.s_addr = inet_addr(str);
396     if (addr.s_addr == INADDR_NONE)
397     return ARES_SUCCESS;
398     newserv = realloc(*servers, (*nservers + 1) * sizeof(struct server_state));
399     if (!newserv)
400     return ARES_ENOMEM;
401     newserv[*nservers].addr = addr;
402     *servers = newserv;
403     (*nservers)++;
404     return ARES_SUCCESS;
405     }
406    
407     static int config_sortlist(struct apattern **sortlist, int *nsort,
408     const char *str)
409     {
410     struct apattern pat, *newsort;
411     const char *q;
412    
413     /* Add sortlist entries. */
414     while (*str && *str != ';')
415     {
416     q = str;
417     while (*q && *q != '/' && *q != ';' && !isspace((unsigned char)*q))
418     q++;
419     if (ip_addr(str, q - str, &pat.addr) == 0)
420     {
421     /* We have a pattern address; now determine the mask. */
422     if (*q == '/')
423     {
424     str = q + 1;
425     while (*q && *q != ';' && !isspace((unsigned char)*q))
426     q++;
427     if (ip_addr(str, q - str, &pat.mask) != 0)
428     natural_mask(&pat);
429     }
430     else
431     natural_mask(&pat);
432    
433     /* Add this pattern to our list. */
434     newsort = realloc(*sortlist, (*nsort + 1) * sizeof(struct apattern));
435     if (!newsort)
436     return ARES_ENOMEM;
437     newsort[*nsort] = pat;
438     *sortlist = newsort;
439     (*nsort)++;
440     }
441     else
442     {
443     while (*q && *q != ';' && !isspace((unsigned char)*q))
444     q++;
445     }
446     str = q;
447     while (isspace((unsigned char)*str))
448     str++;
449     }
450    
451     return ARES_SUCCESS;
452     }
453    
454     static int set_search(ares_channel channel, const char *str)
455     {
456     int n;
457     const char *p, *q;
458    
459     /* Count the domains given. */
460     n = 0;
461     p = str;
462     while (*p)
463     {
464     while (*p && !isspace((unsigned char)*p))
465     p++;
466     while (isspace((unsigned char)*p))
467     p++;
468     n++;
469     }
470    
471     channel->domains = malloc(n * sizeof(char *));
472     if (!channel->domains && n)
473     return ARES_ENOMEM;
474    
475     /* Now copy the domains. */
476     n = 0;
477     p = str;
478     while (*p)
479     {
480     channel->ndomains = n;
481     q = p;
482     while (*q && !isspace((unsigned char)*q))
483     q++;
484     channel->domains[n] = malloc(q - p + 1);
485     if (!channel->domains[n])
486     return ARES_ENOMEM;
487     memcpy(channel->domains[n], p, q - p);
488     channel->domains[n][q - p] = 0;
489     p = q;
490     while (isspace((unsigned char)*p))
491     p++;
492     n++;
493     }
494     channel->ndomains = n;
495    
496     return ARES_SUCCESS;
497     }
498    
499     static int set_options(ares_channel channel, const char *str)
500     {
501     const char *p, *q, *val;
502    
503     p = str;
504     while (*p)
505     {
506     q = p;
507     while (*q && !isspace((unsigned char)*q))
508     q++;
509     val = try_option(p, q, "ndots:");
510     if (val && channel->ndots == -1)
511     channel->ndots = atoi(val);
512     val = try_option(p, q, "retrans:");
513     if (val && channel->timeout == -1)
514     channel->timeout = atoi(val);
515     val = try_option(p, q, "retry:");
516     if (val && channel->tries == -1)
517     channel->tries = atoi(val);
518     p = q;
519     while (isspace((unsigned char)*p))
520     p++;
521     }
522    
523     return ARES_SUCCESS;
524     }
525    
526     static char *try_config(char *s, char *opt)
527     {
528     int len;
529    
530     len = strlen(opt);
531     if (strncmp(s, opt, len) != 0 || !isspace((unsigned char)s[len]))
532     return NULL;
533     s += len;
534     while (isspace((unsigned char)*s))
535     s++;
536     return s;
537     }
538    
539     static const char *try_option(const char *p, const char *q, const char *opt)
540     {
541     int len;
542    
543     len = strlen(opt);
544     return (q - p > len && strncmp(p, opt, len) == 0) ? p + len : NULL;
545     }
546    
547     static int ip_addr(const char *s, int len, struct in_addr *addr)
548     {
549     char ipbuf[16];
550    
551     /* Four octets and three periods yields at most 15 characters. */
552     if (len > 15)
553     return -1;
554     memcpy(ipbuf, s, len);
555     ipbuf[len] = 0;
556    
557     addr->s_addr = inet_addr(ipbuf);
558     if (addr->s_addr == INADDR_NONE && strcmp(ipbuf, "255.255.255.255") != 0)
559     return -1;
560     return 0;
561     }
562    
563     static void natural_mask(struct apattern *pat)
564     {
565     struct in_addr addr;
566    
567     /* Store a host-byte-order copy of pat in a struct in_addr. Icky,
568     * but portable.
569     */
570     addr.s_addr = ntohl(pat->addr.s_addr);
571    
572     /* This is out of date in the CIDR world, but some people might
573     * still rely on it.
574     */
575     if (IN_CLASSA(addr.s_addr))
576     pat->mask.s_addr = htonl(IN_CLASSA_NET);
577     else if (IN_CLASSB(addr.s_addr))
578     pat->mask.s_addr = htonl(IN_CLASSB_NET);
579     else
580     pat->mask.s_addr = htonl(IN_CLASSC_NET);
581     }

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