src/network/resolvconf.c

   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
   8 int __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;
  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
  84 no_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 }