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Use dns_decode for packets from client

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This commit is contained in:
Erik Ekman 2007-01-28 06:47:51 +00:00
parent d1c36f3db4
commit 89c99f1ddf
3 changed files with 91 additions and 99 deletions
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186
src/dns.c
View file

@ -44,9 +44,9 @@
#endif
int dns_decode(char*, int, int, char*, int);
static int dns_write(int, int, char *, int, char);
static void dns_query(int, int, char *, int);
static int decodepacket(const char*, char*, int);
static struct sockaddr_in peer;
static char topdomain[256];
@ -268,6 +268,84 @@ dns_encode(char *buf, size_t buflen, struct query *q, int qr, char *data, size_t
return len;
}
int
dns_decode(char *buf, size_t buflen, struct query *q, int qr, char *packet, size_t packetlen)
{
char rdata[4*1024];
HEADER *header;
short qdcount;
short ancount;
char name[255];
uint32_t ttl;
short class;
short type;
char *data;
short rlen;
int id;
int rv;
rv = 0;
header = (HEADER*)packet;
if (header->qr != qr) {
warnx("header->qr does not match the requested qr");
return -1;
}
data = packet + sizeof(HEADER);
qdcount = ntohs(header->qdcount);
ancount = ntohs(header->ancount);
id = ntohs(header->id);
rlen = 0;
switch (qr) {
case QR_ANSWER:
if(qdcount != 1 || ancount != 1) {
warnx("no query or answer in answer");
return -1;
}
readname(packet, packetlen, &data, name, sizeof(name));
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readname(packet, packetlen, &data, name, sizeof(name));
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readlong(packet, &data, &ttl);
readshort(packet, &data, &rlen);
rv = MIN(rlen, sizeof(rdata));
readdata(packet, &data, rdata, rv);
if(type == T_NULL && rv > 2) {
rv = MIN(rv, buflen);
memcpy(buf, rdata, rv);
}
break;
case QR_QUERY:
if (qdcount != 1) {
warnx("no query on query");
return -1;
}
readname(packet, packetlen, &data, name, sizeof(name) -1);
name[256] = 0;
readshort(packet, &data, &type);
readshort(packet, &data, &class);
strncpy(q->name, name, 257);
q->type = type;
q->id = id;
rv = decodepacket(name, buf, buflen);
break;
}
return rv;
}
static void
dns_query(int fd, int id, char *host, int type)
{
@ -339,68 +417,7 @@ dns_read(int fd, char *buf, int buflen)
dns_send_chunk(fd);
}
}
return dns_decode(buf, buflen, QR_ANSWER, packet, r);
}
int
dns_decode(char *outbuf, int buflen, int qr, char *packet, int packetlen)
{
char rdata[4*1024];
HEADER *header;
short qdcount;
short ancount;
char name[255];
uint32_t ttl;
short class;
short type;
char *data;
short rlen;
int rv;
rv = 0;
header = (HEADER*)packet;
if (header->qr != qr) {
warnx("header->qr does not match the requested qr");
return -1;
}
data = packet + sizeof(HEADER);
qdcount = ntohs(header->qdcount);
ancount = ntohs(header->ancount);
rlen = 0;
switch (qr) {
case QR_ANSWER:
if(qdcount != 1 || ancount != 1) {
warnx("no query or answer in answer");
return -1;
}
readname(packet, packetlen, &data, name, sizeof(name));
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readname(packet, packetlen, &data, name, sizeof(name));
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readlong(packet, &data, &ttl);
readshort(packet, &data, &rlen);
rv = MIN(rlen, sizeof(rdata));
readdata(packet, &data, rdata, rv);
if(type == T_NULL && rv > 2) {
rv = MIN(rv, buflen);
memcpy(outbuf, rdata, rv);
}
break;
case QR_QUERY:
errx(1, "unimplemented query behavior");
break;
}
return rv;
return dns_decode(buf, buflen, NULL, QR_ANSWER, packet, r);
}
int
@ -466,47 +483,22 @@ decodepacket(const char *name, char *buf, int buflen)
int
dnsd_read(int fd, struct query *q, char *buf, int buflen)
{
int r;
int rv;
short id;
short type;
short class;
short qdcount;
char *data;
char name[257];
HEADER *header;
socklen_t addrlen;
char packet[64*1024];
struct sockaddr_in from;
char packet[64*1024];
socklen_t addrlen;
int len;
int rv;
int r;
addrlen = sizeof(struct sockaddr);
r = recvfrom(fd, packet, sizeof(packet), 0, (struct sockaddr*)&from, &addrlen);
if (r >= sizeof(HEADER)) {
header = (HEADER*)packet;
len = dns_decode(buf, buflen, q, QR_QUERY, packet, r);
id = ntohs(header->id);
data = packet + sizeof(HEADER);
if(!header->qr) {
qdcount = ntohs(header->qdcount);
if(qdcount == 1) {
readname(packet, r, &data, name, sizeof(name) -1);
name[256] = 0;
readshort(packet, &data, &type);
readshort(packet, &data, &class);
strncpy(q->name, name, 257);
q->type = type;
q->id = id;
q->fromlen = addrlen;
memcpy((struct sockaddr*)&q->from, (struct sockaddr*)&from, addrlen);
rv = decodepacket(name, buf, buflen);
}
}
q->fromlen = addrlen;
memcpy((struct sockaddr*)&q->from, (struct sockaddr*)&from, addrlen);
rv = len;
} else if (r < 0) { // Error
perror("recvfrom");
rv = 0;

2
src/dns.h
View file

@ -29,7 +29,7 @@ void dns_login(int, char *, int);
int dns_read(int, char *, int);
int dns_encode_hostname(const char *, char *, int);
int dns_encode(char *, size_t, struct query *, int, char *, size_t);
int dns_decode(char *, int, int, char *, int);
int dns_decode(char *, size_t, struct query *, int, char *, size_t);
extern struct sockaddr_in peer;

2
tests/dns.c
View file

@ -150,7 +150,7 @@ START_TEST(test_decode_response)
len = sizeof(buf);
ret = dns_decode(buf, len, QR_ANSWER, answerPacket, sizeof(answerPacket)-1);
ret = dns_decode(buf, len, NULL, QR_ANSWER, answerPacket, sizeof(answerPacket)-1);
fail_unless(strncmp(msgData, buf, sizeof(msgData)) == 0, "Did not extract expected data");
fail_unless(ret == strlen(msgData), va_str("Bad data length: %d, expected %d", ret, strlen(msgData)));
}