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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
/* RFC2136 DNS inform - necessary for Win2k3 DNS servers */
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ndb.h>
#include <ip.h>
#include "dns.h"
enum {
FQDNMAX = 255,
};
char *errmsgs[] = {
[0] "ok",
[1] "request format error",
[2] "internal server error",
[3] "domain name does not exist",
[4] "request not supported",
[5] "permission denied",
[6] "domain name already exists",
[7] "resource record already exists",
[8] "resource record does not exist",
[9] "server not authoritative",
[10] "domain name not in zone",
};
void
usage(void)
{
fprint(2, "usage: %s [-x netmtpt]\n", argv0);
exits("usage");
}
void
ding(void *, char *msg)
{
if(strstr(msg, "alarm") != nil)
noted(NCONT);
noted(NDFLT);
}
int
g16(uchar **p)
{
int n;
n = *(*p)++ << 8;
n |= *(*p)++;
return n;
}
void
p16(uchar **p, int n)
{
*(*p)++ = n >> 8;
*(*p)++ = n;
}
void
p32(uchar **p, int n)
{
*(*p)++ = n >> 24;
*(*p)++ = n >> 16;
*(*p)++ = n >> 8;
*(*p)++ = n;
}
void
pmem(uchar **p, void *v, int len)
{
memmove(*p, v, len);
*p += len;
}
void
pname(uchar **p, char *s)
{
uchar *len;
while (*s){
len = (*p)++;
while(*s && *s != '.')
*(*p)++ = *s++;
*len = *p - len - 1;
if(*s == '.')
s++;
}
*(*p)++ = 0;
}
void
main(int argc, char *argv[])
{
int debug, len, fd;
uint err;
char *sysname, *dnsdomain, *dom, *inform, *ns, net[32];
uchar *p, buf[4096], addr[IPv4addrlen], v6addr[IPaddrlen];
ushort txid;
Ndb *db;
Ndbtuple *t, *tt;
static char *query[] = { "dom", "dnsdomain", "ns", "inform" };
fmtinstall('I', eipfmt);
fmtinstall('V', eipfmt);
setnetmtpt(net, sizeof net, nil);
debug = 0;
ns = nil;
dom = nil;
inform = nil;
dnsdomain = nil;
ARGBEGIN{
case 'd':
debug = 1;
break;
case 'x':
setnetmtpt(net, sizeof net, EARGF(usage()));
break;
default:
usage();
}ARGEND;
if(argc != 0)
usage();
if((sysname = getenv("sysname")) == nil)
sysfatal("$sysname not set");
if((db = ndbopen(nil)) == nil)
sysfatal("can't open ndb: %r");
tt = ndbipinfo(db, "sys", sysname, query, nelem(query));
for(t = tt; t; t = t->entry){
if(strcmp(t->attr, "ns") == 0)
ns = t->val;
else if(strcmp(t->attr, "dom") == 0)
dom = t->val;
else if(strcmp(t->attr, "dnsdomain") == 0)
dnsdomain = t->val;
else if(strcmp(t->attr, "inform") == 0)
inform = t->val;
}
ndbfree(tt);
ndbclose(db);
if(inform)
dom = inform;
if(!ns)
sysfatal("no relevant ns=");
if(!dom)
sysfatal("no relevant dom=");
if(!dnsdomain)
sysfatal("no relevant dnsdomain=");
myipaddr(v6addr, net);
memmove(addr, v6addr + IPaddrlen - IPv4addrlen, IPv4addrlen);
if(debug){
print("ip=%V\n", addr);
print("ns=%s\n", ns);
print("dnsdomain=%s\n", dnsdomain);
print("dom=%s\n", dom);
}
if((fd = dial(netmkaddr(ns, "udp", "dns"), 0, 0, 0)) < 0)
sysfatal("can't dial %s: %r", ns);
txid = time(nil) + getpid();
p = buf;
p16(&p, txid); /* ID */
p16(&p, 5<<11); /* flags */
p16(&p, 1); /* # Zones */
p16(&p, 0); /* # prerequisites */
p16(&p, 2); /* # updates */
p16(&p, 0); /* # additionals */
pname(&p, dnsdomain); /* zone */
p16(&p, Tsoa); /* zone type */
p16(&p, Cin); /* zone class */
/* delete old name */
pname(&p, dom); /* name */
p16(&p, Ta); /* type: v4 addr */
p16(&p, Call); /* class */
p32(&p, 0); /* TTL */
p16(&p, 0); /* data len */
/* add new A record */
pname(&p, dom); /* name */
p16(&p, Ta); /* type: v4 addr */
p16(&p, Cin); /* class */
p32(&p, 60*60*25); /* TTL (25 hours) */
p16(&p, IPv4addrlen); /* data len */
pmem(&p, addr, IPv4addrlen); /* v4 address */
len = p - buf;
if(write(fd, buf, len) != len)
sysfatal("write failed: %r");
notify(ding);
alarm(3000);
do{
if(read(fd, buf, sizeof buf) < 0)
sysfatal("timeout");
p = buf;
}while(g16(&p) != txid);
alarm(0);
close(fd);
err = g16(&p) & 7;
if(err != 0 && err != 7) /* err==7 is just a "yes, I know" warning */
if(err < nelem(errmsgs))
sysfatal("%s", errmsgs[err]);
else
sysfatal("unknown dns server error %d", err);
exits(0);
}
|
