libc-top-half/musl/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 <stdlib.h>
   7 #include <netinet/in.h>
   8
   9 int __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
  85 no_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 }