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
|
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>
#include <ndb.h>
#include "dns.h"
#include "ip.h"
static int domount;
static char *mtpt, *dns, *srv;
static int
setup(int argc, char **argv)
{
int fd;
if(argc == 1){
domount = 0;
mtpt = argv[0];
}
fd = open(dns, ORDWR);
if(fd < 0){
if(domount == 0)
sysfatal("can't open %s: %r", dns);
fd = open(srv, ORDWR);
if(fd < 0)
sysfatal("can't open %s: %r", srv);
if(mount(fd, -1, mtpt, MBEFORE, "") < 0)
sysfatal("can't mount(%s, %s): %r", srv, mtpt);
fd = open(dns, ORDWR);
if(fd < 0)
sysfatal("can't open %s: %r", dns);
}
return fd;
}
static void
querydns(int fd, char *line, int n)
{
char buf[1024];
seek(fd, 0, 0);
if(write(fd, line, n) != n) {
print("!%r\n");
return;
}
seek(fd, 0, 0);
buf[0] = '\0';
while((n = read(fd, buf, sizeof(buf))) > 0){
buf[n] = '\0';
print("%s\n", buf);
}
}
static void
query(int fd)
{
int n, len;
char *lp, *p, *np;
char buf[1024], line[1024];
Biobuf in;
Binit(&in, 0, OREAD);
for(print("> "); lp = Brdline(&in, '\n'); print("> ")){
n = Blinelen(&in) -1;
while(isspace(lp[n]))
lp[n--] = 0;
n++;
while(isspace(*lp)){
lp++;
n--;
}
if(!*lp)
continue;
strcpy(line, lp);
/* default to an "ip" request if alpha, "ptr" if numeric */
if(strchr(line, ' ') == nil)
if(strcmp(ipattr(line), "ip") == 0) {
strcat(line, " ptr");
n += 4;
} else {
strcat(line, " ip");
n += 3;
}
/* inverse queries may need to be permuted */
if(n > 4 && strcmp(" ptr", &line[n-4]) == 0 &&
cistrstr(line, ".arpa") == nil){
/* TODO: reversing v6 addrs is harder */
for(p = line; *p; p++)
if(*p == ' '){
*p = '.';
break;
}
np = buf;
len = 0;
while(p >= line){
len++;
p--;
if(*p == '.'){
memmove(np, p+1, len);
np += len;
len = 0;
}
}
memmove(np, p+1, len);
np += len;
strcpy(np, "in-addr.arpa ptr"); /* TODO: ip6.arpa for v6 */
strcpy(line, buf);
n = strlen(line);
}
querydns(fd, line, n);
}
Bterm(&in);
}
void
main(int argc, char *argv[])
{
mtpt = "/net";
dns = "/net/dns";
srv = "/srv/dns";
domount = 1;
ARGBEGIN {
case 'x':
mtpt = "/net.alt";
dns = "/net.alt/dns";
srv = "/srv/dns_net.alt";
break;
default:
fprint(2, "usage: %s [-x] [dns-mount-point]\n", argv0);
exits("usage");
} ARGEND;
query(setup(argc, argv));
exits(0);
}
|
