summaryrefslogtreecommitdiff
path: root/ucspi-tcp-0.88/dns_rcrw.c
blob: 6f215ac977b05189d184ccbe0573734a0dc41c83 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
#include "taia.h"
#include "env.h"
#include "byte.h"
#include "str.h"
#include "openreadclose.h"
#include "dns.h"

static stralloc data = {0};

static int init(stralloc *rules)
{
  char host[256];
  char *x;
  int i;
  int j;
  int k;

  if (!stralloc_copys(rules,"")) return -1;

  x = env_get("DNSREWRITEFILE");
  if (!x) x = "/etc/dnsrewrite";

  i = openreadclose(x,&data,64);
  if (i == -1) return -1;

  if (i) {
    if (!stralloc_append(&data,"\n")) return -1;
    i = 0;
    for (j = 0;j < data.len;++j)
      if (data.s[j] == '\n') {
        if (!stralloc_catb(rules,data.s + i,j - i)) return -1;
        while (rules->len) {
          if (rules->s[rules->len - 1] != ' ')
          if (rules->s[rules->len - 1] != '\t')
          if (rules->s[rules->len - 1] != '\r')
            break;
          --rules->len;
        }
        if (!stralloc_0(rules)) return -1;
        i = j + 1;
      }
    return 0;
  }

  x = env_get("LOCALDOMAIN");
  if (x) {
    if (!stralloc_copys(&data,x)) return -1;
    if (!stralloc_append(&data," ")) return -1;
    if (!stralloc_copys(rules,"?:")) return -1;
    i = 0;
    for (j = 0;j < data.len;++j)
      if (data.s[j] == ' ') {
        if (!stralloc_cats(rules,"+.")) return -1;
        if (!stralloc_catb(rules,data.s + i,j - i)) return -1;
        i = j + 1;
      }
    if (!stralloc_0(rules)) return -1;
    if (!stralloc_cats(rules,"*.:")) return -1;
    if (!stralloc_0(rules)) return -1;
    return 0;
  }

  i = openreadclose("/etc/resolv.conf",&data,64);
  if (i == -1) return -1;

  if (i) {
    if (!stralloc_append(&data,"\n")) return -1;
    i = 0;
    for (j = 0;j < data.len;++j)
      if (data.s[j] == '\n') {
        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)) {
          if (!stralloc_copys(rules,"?:")) return -1;
          i += 7;
          while (i < j) {
            k = byte_chr(data.s + i,j - i,' ');
            k = byte_chr(data.s + i,k,'\t');
            if (!k) { ++i; continue; }
            if (!stralloc_cats(rules,"+.")) return -1;
            if (!stralloc_catb(rules,data.s + i,k)) return -1;
            i += k;
          }
          if (!stralloc_0(rules)) return -1;
          if (!stralloc_cats(rules,"*.:")) return -1;
          if (!stralloc_0(rules)) return -1;
          return 0;
        }
        i = j + 1;
      }
  }

  host[0] = 0;
  if (gethostname(host,sizeof host) == -1) return -1;
  host[(sizeof host) - 1] = 0;
  i = str_chr(host,'.');
  if (host[i]) {
    if (!stralloc_copys(rules,"?:")) return -1;
    if (!stralloc_cats(rules,host + i)) return -1;
    if (!stralloc_0(rules)) return -1;
  }
  if (!stralloc_cats(rules,"*.:")) return -1;
  if (!stralloc_0(rules)) return -1;

  return 0;
}

static int ok = 0;
static unsigned int uses;
static struct taia deadline;
static stralloc rules = {0}; /* defined if ok */

int dns_resolvconfrewrite(stralloc *out)
{
  struct taia now;

  taia_now(&now);
  if (taia_less(&deadline,&now)) ok = 0;
  if (!uses) ok = 0;

  if (!ok) {
    if (init(&rules) == -1) return -1;
    taia_uint(&deadline,600);
    taia_add(&deadline,&now,&deadline);
    uses = 10000;
    ok = 1;
  }

  --uses;
  if (!stralloc_copy(out,&rules)) return -1;
  return 0;
}