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
131
132
133
134
135
136
137
138
139
140
141
|
#include <unistd.h>
#include "taia.h"
#include "env.h"
#include "byte.h"
#include "str.h"
#include "readclose.h"
#include "dnsresolv.h"
/**
@file dns_rcrw.c
@author djb
@source ucspi-tcp
@brief DNS receive rewrite
*/
static stralloc data = {0};
static int init(stralloc *rules)
{
char host[256];
const char *x;
int i;
int j;
int k;
if (!stralloc_copys(rules,"")) return DNS_MEM;
x = env_get("DNSREWRITEFILE");
if (!x) x = "/etc/dnsrewrite";
i = openreadclose(x,&data,64);
if (i == -1) return DNS_INT;
if (i) {
if (!stralloc_append(&data,"\n")) return DNS_MEM;
i = 0;
for (j = 0; j < data.len; ++j)
if (data.s[j] == '\n') {
if (!stralloc_catb(rules,data.s + i,j - i)) return DNS_MEM;
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 DNS_MEM;
i = j + 1;
}
return 0;
}
x = env_get("LOCALDOMAIN");
if (x) {
if (!stralloc_copys(&data,x)) return DNS_MEM;
if (!stralloc_append(&data," ")) return DNS_MEM;
if (!stralloc_copys(rules,"?:")) return DNS_MEM;
i = 0;
for (j = 0; j < data.len; ++j)
if (data.s[j] == ' ') {
if (!stralloc_cats(rules,"+.")) return DNS_MEM;
if (!stralloc_catb(rules,data.s + i,j - i)) return DNS_MEM;
i = j + 1;
}
if (!stralloc_0(rules)) return DNS_MEM;
if (!stralloc_cats(rules,"*.:")) return DNS_MEM;
if (!stralloc_0(rules)) return DNS_MEM;
return 0;
}
i = openreadclose("/etc/resolv.conf",&data,64);
if (i == -1) return DNS_INT;
if (i) {
if (!stralloc_append(&data,"\n")) return DNS_MEM;
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 DNS_MEM;
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 DNS_MEM;
if (!stralloc_catb(rules,data.s + i,k)) return DNS_MEM;
i += k;
}
if (!stralloc_0(rules)) return DNS_MEM;
if (!stralloc_cats(rules,"*.:")) return DNS_MEM;
if (!stralloc_0(rules)) return DNS_MEM;
return 0;
}
i = j + 1;
}
}
host[0] = 0;
if (gethostname(host,sizeof(host)) == -1) return DNS_ERR;
host[(sizeof(host)) - 1] = 0;
i = str_chr(host,'.');
if (host[i]) {
if (!stralloc_copys(rules,"?:")) return DNS_MEM;
if (!stralloc_cats(rules,host + i)) return DNS_MEM;
if (!stralloc_0(rules)) return DNS_MEM;
}
if (!stralloc_cats(rules,"*.:")) return DNS_MEM;
if (!stralloc_0(rules)) return DNS_MEM;
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) < 0) return DNS_INT;
taia_uint(&deadline,600);
taia_add(&deadline,&now,&deadline);
uses = 10000;
ok = 1;
}
--uses;
if (!stralloc_copy(out,&rules)) return DNS_MEM;
return 0;
}
|
