mirror of
https://github.com/yarrick/iodine.git
synced 2024-11-16 12:53:17 +00:00
#75, update dns parsing
This commit is contained in:
Erik Ekman
parent
3940f4e5ff
commit
bd4a4eb24c
176
src/dns.c
176
src/dns.c
|
|
@ -39,6 +39,8 @@
|
|||
#include "encoding.h"
|
||||
#include "read.h"
|
||||
|
||||
#define CHECKLEN(x) if (buflen - (p-buf) < (x)) return 0
|
||||
|
||||
int
|
||||
dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_t datalen)
|
||||
{
|
||||
|
|
@ -47,6 +49,9 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
|
|||
char *p;
|
||||
int len;
|
||||
|
||||
if (buflen < sizeof(HEADER))
|
||||
return 0;
|
||||
|
||||
memset(buf, 0, buflen);
|
||||
|
||||
header = (HEADER*)buf;
|
||||
|
|
@ -68,29 +73,80 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
|
|||
|
||||
name = 0xc000 | ((p - buf) & 0x3fff);
|
||||
|
||||
putname(&p, sizeof(q->name), q->name);
|
||||
/* Question section */
|
||||
putname(&p, buflen - (p - buf), q->name);
|
||||
|
||||
CHECKLEN(4);
|
||||
putshort(&p, q->type);
|
||||
putshort(&p, C_IN);
|
||||
|
||||
/* Answer section */
|
||||
CHECKLEN(10);
|
||||
putshort(&p, name);
|
||||
if (q->type == T_A)
|
||||
putshort(&p, T_CNAME); /* answer CNAME to A question */
|
||||
else
|
||||
putshort(&p, q->type);
|
||||
putshort(&p, C_IN);
|
||||
putlong(&p, 0);
|
||||
putlong(&p, 0); /* TTL */
|
||||
|
||||
if (q->type == T_CNAME || q->type == T_A || q->type == T_MX)
|
||||
{
|
||||
/* data is expected to be like "Hblabla.host.name.com\0" */
|
||||
|
||||
char *startp = p;
|
||||
int namelen;
|
||||
|
||||
p += 2; /* skip 2 bytes length */
|
||||
CHECKLEN(2);
|
||||
if (q->type == T_MX)
|
||||
putshort(&p, 10); /* preference */
|
||||
putname(&p, buflen - (p - buf), data);
|
||||
CHECKLEN(0);
|
||||
namelen = p - startp;
|
||||
namelen -= 2;
|
||||
putshort(&startp, namelen);
|
||||
}
|
||||
else if (q->type == T_TXT)
|
||||
{
|
||||
/* TXT has binary or base-X data */
|
||||
char *startp = p;
|
||||
int txtlen;
|
||||
|
||||
p += 2; /* skip 2 bytes length */
|
||||
puttxtbin(&p, buflen - (p - buf), data, datalen);
|
||||
CHECKLEN(0);
|
||||
txtlen = p - startp;
|
||||
txtlen -= 2;
|
||||
putshort(&startp, txtlen);
|
||||
}
|
||||
else
|
||||
{
|
||||
/* NULL has raw binary data */
|
||||
datalen = MIN(datalen, buflen - (p - buf));
|
||||
CHECKLEN(2);
|
||||
putshort(&p, datalen);
|
||||
CHECKLEN(datalen);
|
||||
putdata(&p, data, datalen);
|
||||
CHECKLEN(0);
|
||||
}
|
||||
|
||||
break;
|
||||
case QR_QUERY:
|
||||
/* Note that iodined also uses this for forward queries */
|
||||
|
||||
header->qdcount = htons(1);
|
||||
header->arcount = htons(1);
|
||||
|
||||
putname(&p, datalen, data);
|
||||
putname(&p, buflen - (p - buf), data);
|
||||
|
||||
CHECKLEN(4);
|
||||
putshort(&p, q->type);
|
||||
putshort(&p, C_IN);
|
||||
|
||||
/* EDNS0 */
|
||||
/* EDNS0 to advertise maximum response length
|
||||
(even CNAME/A/MX, 255+255+header would be >512) */
|
||||
CHECKLEN(11);
|
||||
putbyte(&p, 0x00); /* Root */
|
||||
putshort(&p, 0x0029); /* OPT */
|
||||
putshort(&p, 0x1000); /* Payload size: 4096 */
|
||||
|
|
@ -107,6 +163,7 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
|
|||
|
||||
int
|
||||
dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomain)
|
||||
/* Only used when iodined gets an NS type query */
|
||||
{
|
||||
HEADER *header;
|
||||
int len;
|
||||
|
|
@ -117,6 +174,9 @@ dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomai
|
|||
int domain_len;
|
||||
char *p;
|
||||
|
||||
if (buflen < sizeof(HEADER))
|
||||
return 0;
|
||||
|
||||
memset(buf, 0, buflen);
|
||||
|
||||
header = (HEADER*)buf;
|
||||
|
|
@ -148,33 +208,38 @@ dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomai
|
|||
topname = 0xc000 | ((p - buf + domain_len) & 0x3fff);
|
||||
|
||||
/* Query section */
|
||||
putname(&p, sizeof(q->name), q->name); /* Name */
|
||||
putname(&p, buflen - (p - buf), q->name); /* Name */
|
||||
CHECKLEN(4);
|
||||
putshort(&p, q->type); /* Type */
|
||||
putshort(&p, C_IN); /* Class */
|
||||
|
||||
/* Answer section */
|
||||
CHECKLEN(12);
|
||||
putshort(&p, name); /* Name */
|
||||
putshort(&p, q->type); /* Type */
|
||||
putshort(&p, C_IN); /* Class */
|
||||
putlong(&p, 0x3ea7d011); /* TTL */
|
||||
putlong(&p, 3600); /* TTL */
|
||||
putshort(&p, 5); /* Data length */
|
||||
|
||||
/* pointer to ns.topdomain */
|
||||
nsname = 0xc000 | ((p - buf) & 0x3fff);
|
||||
CHECKLEN(5);
|
||||
putbyte(&p, 2);
|
||||
putbyte(&p, 'n');
|
||||
putbyte(&p, 's');
|
||||
putshort(&p, topname); /* Name Server */
|
||||
|
||||
/* Additional data (A-record of NS server) */
|
||||
CHECKLEN(12);
|
||||
putshort(&p, nsname); /* Name Server */
|
||||
putshort(&p, T_A); /* Type */
|
||||
putshort(&p, C_IN); /* Class */
|
||||
putlong(&p, 0x3ea7d011); /* TTL */
|
||||
putlong(&p, 3600); /* TTL */
|
||||
putshort(&p, 4); /* Data length */
|
||||
|
||||
/* ugly hack to output IP address */
|
||||
domain = (char *) &q->destination;
|
||||
CHECKLEN(4);
|
||||
putbyte(&p, *domain++);
|
||||
putbyte(&p, *domain++);
|
||||
putbyte(&p, *domain++);
|
||||
|
|
@ -184,6 +249,8 @@ dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomai
|
|||
return len;
|
||||
}
|
||||
|
||||
#undef CHECKLEN
|
||||
|
||||
unsigned short
|
||||
dns_get_id(char *packet, size_t packetlen)
|
||||
{
|
||||
|
|
@ -196,6 +263,8 @@ dns_get_id(char *packet, size_t packetlen)
|
|||
return ntohs(header->id);
|
||||
}
|
||||
|
||||
#define CHECKLEN(x) if (packetlen - (data-packet) < (x)) return 0
|
||||
|
||||
int
|
||||
dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, size_t packetlen)
|
||||
{
|
||||
|
|
@ -235,27 +304,50 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
|
|||
|
||||
switch (qr) {
|
||||
case QR_ANSWER:
|
||||
if(qdcount != 1 || ancount != 1) {
|
||||
if(qdcount < 1 || ancount < 1) {
|
||||
/* We may get both CNAME and A, then ancount=2 */
|
||||
switch (header->rcode) {
|
||||
case REFUSED:
|
||||
case NOERROR: /* 0 */
|
||||
if (header->tc)
|
||||
warnx("Got TRUNCATION as reply: response too long for DNS path");
|
||||
else
|
||||
warnx("Got reply without error, but also without question and/or answer");
|
||||
break;
|
||||
|
||||
case FORMERR: /* 1 */
|
||||
warnx("Got FORMERR as reply: server does not understand our request");
|
||||
break;
|
||||
|
||||
case SERVFAIL: /* 2 */
|
||||
if (qdcount >= 1
|
||||
&& packetlen >= sizeof(HEADER) + 2
|
||||
&& (data[1] == 'r' || data[1] == 'R'))
|
||||
warnx("Got SERVFAIL as reply on earlier fragsize autoprobe");
|
||||
else if (qdcount >= 1
|
||||
&& packetlen >= sizeof(HEADER) + 2
|
||||
&& (data[1] < '0' || data[1] > '9')
|
||||
&& (data[1] < 'a' || data[1] > 'f')
|
||||
&& (data[1] < 'A' || data[1] > 'F')
|
||||
&& data[1] != 'p' && data[1] != 'P')
|
||||
warnx("Got SERVFAIL as reply on earlier config setting");
|
||||
else
|
||||
warnx("Got SERVFAIL as reply: server failed or recursion timeout");
|
||||
break;
|
||||
|
||||
case NXDOMAIN: /* 3 */
|
||||
warnx("Got NXDOMAIN as reply: domain does not exist");
|
||||
break;
|
||||
|
||||
case NOTIMP: /* 4 */
|
||||
warnx("Got NOTIMP as reply: server does not support our request");
|
||||
break;
|
||||
|
||||
case REFUSED: /* 5 */
|
||||
warnx("Got REFUSED as reply");
|
||||
break;
|
||||
|
||||
case NOTIMP:
|
||||
warnx("Got NOTIMP as reply");
|
||||
break;
|
||||
|
||||
case NXDOMAIN:
|
||||
warnx("Got NXDOMAIN as reply");
|
||||
break;
|
||||
|
||||
case SERVFAIL:
|
||||
warnx("Got SERVFAIL as reply");
|
||||
break;
|
||||
|
||||
case NOERROR:
|
||||
default:
|
||||
warnx("no query or answer in reply packet");
|
||||
warnx("Got RCODE %u as reply", (unsigned int) header->rcode);
|
||||
break;
|
||||
}
|
||||
return -1;
|
||||
|
|
@ -265,33 +357,65 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
|
|||
q->id = id;
|
||||
|
||||
readname(packet, packetlen, &data, name, sizeof(name));
|
||||
CHECKLEN(4);
|
||||
readshort(packet, &data, &type);
|
||||
readshort(packet, &data, &class);
|
||||
|
||||
/* Assume that first answer is NULL/CNAME that we wanted */
|
||||
readname(packet, packetlen, &data, name, sizeof(name));
|
||||
CHECKLEN(10);
|
||||
readshort(packet, &data, &type);
|
||||
readshort(packet, &data, &class);
|
||||
readlong(packet, &data, &ttl);
|
||||
readshort(packet, &data, &rlen);
|
||||
|
||||
if (type == T_NULL) {
|
||||
rv = MIN(rlen, sizeof(rdata));
|
||||
rv = readdata(packet, &data, rdata, rv);
|
||||
|
||||
if(type == T_NULL && rv >= 2 && buf) {
|
||||
if (rv >= 2 && buf) {
|
||||
rv = MIN(rv, buflen);
|
||||
memcpy(buf, rdata, rv);
|
||||
}
|
||||
/* "else rv=0;" here? */
|
||||
}
|
||||
if ((type == T_CNAME || type == T_MX) && buf) {
|
||||
if (type == T_MX)
|
||||
data += 2; /* skip preference */
|
||||
memset(name, 0, sizeof(name));
|
||||
readname(packet, packetlen, &data, name, sizeof(name) - 1);
|
||||
name[sizeof(name)-1] = '\0';
|
||||
strncpy(buf, name, buflen);
|
||||
buf[buflen - 1] = '\0';
|
||||
rv = strlen(buf);
|
||||
}
|
||||
if (type == T_TXT && buf) {
|
||||
rv = readtxtbin(packet, &data, rlen, rdata, sizeof(rdata));
|
||||
if (rv >= 1) {
|
||||
rv = MIN(rv, buflen);
|
||||
memcpy(buf, rdata, rv);
|
||||
}
|
||||
}
|
||||
if (q != NULL)
|
||||
q->type = type;
|
||||
break;
|
||||
case QR_QUERY:
|
||||
if (qdcount != 1) {
|
||||
if (qdcount < 1) {
|
||||
warnx("no question section in name query");
|
||||
return -1;
|
||||
}
|
||||
|
||||
memset(name, 0, sizeof(name));
|
||||
readname(packet, packetlen, &data, name, sizeof(name) - 1);
|
||||
name[sizeof(name)-1] = '\0';
|
||||
CHECKLEN(4);
|
||||
readshort(packet, &data, &type);
|
||||
readshort(packet, &data, &class);
|
||||
|
||||
if (q == NULL) {
|
||||
rv = 0;
|
||||
break;
|
||||
}
|
||||
|
||||
strncpy(q->name, name, sizeof(q->name));
|
||||
q->name[sizeof(q->name) - 1] = '\0';
|
||||
q->type = type;
|
||||
|
|
|
|||
Loading…
Reference in a new issue