1#include "lookup.h"
 2#include "stdio_impl.h"
 3#include <ctype.h>
 4#include <errno.h>
 5#include <string.h>
 6#include <stdlib.h>
 7#include <netinet/in.h>
 8
 9int __get_resolv_conf(struct resolvconf *conf, char *search, size_t search_sz)
10{
11	char line[256];
12	unsigned char _buf[256];
13	FILE *f, _f;
14	int nns = 0;
15
16	conf->ndots = 1;
17	conf->timeout = 5;
18	conf->attempts = 2;
19	if (search) *search = 0;
20
21	f = __fopen_rb_ca("/etc/resolv.conf", &_f, _buf, sizeof _buf);
22	if (!f) switch (errno) {
23	case ENOENT:
24	case ENOTDIR:
25	case EACCES:
26		goto no_resolv_conf;
27	default:
28		return -1;
29	}
30
31	while (fgets(line, sizeof line, f)) {
32		char *p, *z;
33		if (!strchr(line, '\n') && !feof(f)) {
34			/* Ignore lines that get truncated rather than
35			 * potentially misinterpreting them. */
36			int c;
37			do c = getc(f);
38			while (c != '\n' && c != EOF);
39			continue;
40		}
41		if (!strncmp(line, "options", 7) && isspace(line[7])) {
42			p = strstr(line, "ndots:");
43			if (p && isdigit(p[6])) {
44				p += 6;
45				unsigned long x = strtoul(p, &z, 10);
46				if (z != p) conf->ndots = x > 15 ? 15 : x;
47			}
48			p = strstr(line, "attempts:");
49			if (p && isdigit(p[9])) {
50				p += 9;
51				unsigned long x = strtoul(p, &z, 10);
52				if (z != p) conf->attempts = x > 10 ? 10 : x;
53			}
54			p = strstr(line, "timeout:");
55			if (p && (isdigit(p[8]) || p[8]=='.')) {
56				p += 8;
57				unsigned long x = strtoul(p, &z, 10);
58				if (z != p) conf->timeout = x > 60 ? 60 : x;
59			}
60			continue;
61		}
62		if (!strncmp(line, "nameserver", 10) && isspace(line[10])) {
63			if (nns >= MAXNS) continue;
64			for (p=line+11; isspace(*p); p++);
65			for (z=p; *z && !isspace(*z); z++);
66			*z=0;
67			if (__lookup_ipliteral(conf->ns+nns, p, AF_UNSPEC) > 0)
68				nns++;
69			continue;
70		}
71
72		if (!search) continue;
73		if ((strncmp(line, "domain", 6) && strncmp(line, "search", 6))
74		    || !isspace(line[6]))
75			continue;
76		for (p=line+7; isspace(*p); p++);
77		size_t l = strlen(p);
78		/* This can never happen anyway with chosen buffer sizes. */
79		if (l >= search_sz) continue;
80		memcpy(search, p, l+1);
81	}
82
83	__fclose_ca(f);
84
85no_resolv_conf:
86	if (!nns) {
87		__lookup_ipliteral(conf->ns, "127.0.0.1", AF_UNSPEC);
88		nns = 1;
89	}
90
91	conf->nns = nns;
92
93	return 0;
94}