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