ericonr
/
dnsquery
mirror of https://github.com/ericonr/dnsquery.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Implement AAAA record parsing.

This commit is contained in:
Érico Nogueira 2021-08-18 11:38:34 -03:00
parent 69f584a78c
commit 3adefb94a0
1 changed files with 31 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
dnsquery.c
View File

@ -1,6 +1,8 @@
/* DNS query
*
* based off of https://datatracker.ietf.org/doc/html/rfc1035
* based off of:
* - https://datatracker.ietf.org/doc/html/rfc1035
* - https://datatracker.ietf.org/doc/html/rfc3596
*
* understanding compression required some study of strace(1) output
* from drill(1) and getent(1)
@ -176,11 +178,35 @@ int main()
uint16_t rdlength = ((uint16_t)r[i] << 8) | r[i+1];
i+=2;
if (type == 1 && class == 1 && rdlength == 4) {
printf("IPv4: %d.%d.%d.%d\n", r[i], r[i+1], r[i+2], r[i+3]);
} else {
fputs("can't interpret answer\n", stderr);
if (class == QCLASS_IN) {
/* desired length */
uint16_t len_d;
/* formatting */
int af;
const char *ip_class;
char ip_s[INET6_ADDRSTRLEN];
if (type == QTYPE_A) {
len_d = 4;
af = AF_INET;
ip_class = "IPv4";
} else if (type == QTYPE_AAAA) {
len_d = 16;
af = AF_INET6;
ip_class = "IPv6";
} else {
ep("unknown qtype", type);
}
if (rdlength != len_d) ep("bad record length", rdlength);
/* address comes over the wire in network order */
if (!inet_ntop(af, r+i, ip_s, sizeof ip_s)) e("bad address");
i+=len_d;
printf("%s: %s\n", ip_class, ip_s);
continue;
}
e("can't interpret answer");
}
return 0;