dns_rcrw.c

   1 #include <unistd.h>
   2 #include "taia.h"
   3 #include "env.h"
   4 #include "byte.h"
   5 #include "str.h"
   6 #include "openreadclose.h"
   7 #include "dns.h"
   8
   9 static stralloc data = {0};
  10
  11 static int init(stralloc *rules)
  12 {
  13   char host[256];
  14   const char *x;
  15   int i;
  16   int j;
  17   int k;
  18
  19   if (!stralloc_copys(rules,"")) return -1;
  20
  21   x = env_get("DNSREWRITEFILE");
  22   if (!x) x = "/etc/dnsrewrite";
  23
  24   i = openreadclose(x,&data,64);
  25   if (i == -1) return -1;
  26
  27   if (i) {
  28     if (!stralloc_append(&data,"\n")) return -1;
  29     i = 0;
  30     for (j = 0;j < data.len;++j)
  31       if (data.s[j] == '\n') {
  32         if (!stralloc_catb(rules,data.s + i,j - i)) return -1;
  33         while (rules->len) {
  34           if (rules->s[rules->len - 1] != ' ')
  35           if (rules->s[rules->len - 1] != '\t')
  36           if (rules->s[rules->len - 1] != '\r')
  37             break;
  38           --rules->len;
  39         }
  40         if (!stralloc_0(rules)) return -1;
  41         i = j + 1;
  42       }
  43     return 0;
  44   }
  45
  46   x = env_get("LOCALDOMAIN");
  47   if (x) {
  48     if (!stralloc_copys(&data,x)) return -1;
  49     if (!stralloc_append(&data," ")) return -1;
  50     if (!stralloc_copys(rules,"?:")) return -1;
  51     i = 0;
  52     for (j = 0;j < data.len;++j)
  53       if (data.s[j] == ' ') {
  54         if (!stralloc_cats(rules,"+.")) return -1;
  55         if (!stralloc_catb(rules,data.s + i,j - i)) return -1;
  56         i = j + 1;
  57       }
  58     if (!stralloc_0(rules)) return -1;
  59     if (!stralloc_cats(rules,"*.:")) return -1;
  60     if (!stralloc_0(rules)) return -1;
  61     return 0;
  62   }
  63
  64   i = openreadclose("/etc/resolv.conf",&data,64);
  65   if (i == -1) return -1;
  66
  67   if (i) {
  68     if (!stralloc_append(&data,"\n")) return -1;
  69     i = 0;
  70     for (j = 0;j < data.len;++j)
  71       if (data.s[j] == '\n') {
  72         if (byte_equal("search ",7,data.s + i) || byte_equal("search\t",7,data.s + i) || byte_equal("domain ",7,data.s + i) || byte_equal("domain\t",7,data.s + i)) {
  73           if (!stralloc_copys(rules,"?:")) return -1;
  74           i += 7;
  75           while (i < j) {
  76             k = byte_chr(data.s + i,j - i,' ');
  77             k = byte_chr(data.s + i,k,'\t');
  78             if (!k) { ++i; continue; }
  79             if (!stralloc_cats(rules,"+.")) return -1;
  80             if (!stralloc_catb(rules,data.s + i,k)) return -1;
  81             i += k;
  82           }
  83           if (!stralloc_0(rules)) return -1;
  84           if (!stralloc_cats(rules,"*.:")) return -1;
  85           if (!stralloc_0(rules)) return -1;
  86           return 0;
  87         }
  88         i = j + 1;
  89       }
  90   }
  91
  92   host[0] = 0;
  93   if (gethostname(host,sizeof host) == -1) return -1;
  94   host[(sizeof host) - 1] = 0;
  95   i = str_chr(host,'.');
  96   if (host[i]) {
  97     if (!stralloc_copys(rules,"?:")) return -1;
  98     if (!stralloc_cats(rules,host + i)) return -1;
  99     if (!stralloc_0(rules)) return -1;
 100   }
 101   if (!stralloc_cats(rules,"*.:")) return -1;
 102   if (!stralloc_0(rules)) return -1;
 103
 104   return 0;
 105 }
 106
 107 static int ok = 0;
 108 static unsigned int uses;
 109 static struct taia deadline;
 110 static stralloc rules = {0}; /* defined if ok */
 111
 112 int dns_resolvconfrewrite(stralloc *out)
 113 {
 114   struct taia now;
 115
 116   taia_now(&now);
 117   if (taia_less(&deadline,&now)) ok = 0;
 118   if (!uses) ok = 0;
 119
 120   if (!ok) {
 121     if (init(&rules) == -1) return -1;
 122     taia_uint(&deadline,600);
 123     taia_add(&deadline,&now,&deadline);
 124     uses = 10000;
 125     ok = 1;
 126   }
 127
 128   --uses;
 129   if (!stralloc_copy(out,&rules)) return -1;
 130   return 0;
 131 }