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Add packet length parameter on readname, add tests

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This commit is contained in:
Erik Ekman 2006-11-06 19:30:35 +00:00
parent 4a4aaa5bb4
commit aeae642fd8
5 changed files with 57 additions and 15 deletions
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10
dns.c
View File

@ -309,12 +309,12 @@ dns_parse_reply(char *outbuf, int buflen, char *packet, int packetlen)
rlen = 0;
if(qdcount == 1) {
readname(packet, &data, name, sizeof(name));
readname(packet, packetlen, &data, name, sizeof(name));
readshort(packet, &data, &type);
readshort(packet, &data, &class);
}
if(ancount == 1) {
readname(packet, &data, name, sizeof(name));
readname(packet, packetlen, &data, name, sizeof(name));
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readlong(packet, &data, &ttl);
@ -455,7 +455,7 @@ dnsd_read(int fd, struct query *q, char *buf, int buflen)
qdcount = ntohs(header->qdcount);
if(qdcount == 1) {
readname(packet, &data, name, sizeof(name) -1);
readname(packet, r, &data, name, sizeof(name) -1);
name[256] = 0;
readshort(packet, &data, &type);
readshort(packet, &data, &class);
@ -469,9 +469,11 @@ dnsd_read(int fd, struct query *q, char *buf, int buflen)
rv = decodepacket(name, buf, buflen);
}
}
} else {
} else if (r < 0) { // Error
perror("recvfrom");
rv = 0;
} else { // Packet too small to be dns protocol
rv = 0;
}
return rv;

2
iodined.c
View File

@ -111,7 +111,7 @@ tunnel(int tun_fd, int dns_fd)
}
if(FD_ISSET(dns_fd, &fds)) {
read = dnsd_read(dns_fd, &q, in, sizeof(in));
if (read < 0)
if (read <= 0)
continue;
if(in[0] == 'H' || in[0] == 'h') {

22
read.c
View File

@ -15,14 +15,16 @@
*/
#include <string.h>
#include <stdio.h>
static int
readname_loop(char *packet, char **src, char *dst, size_t length, size_t loop)
readname_loop(char *packet, int packetlen, char **src, char *dst, size_t length, size_t loop)
{
char *dummy;
char *s;
char *d;
int len;
unsigned offset;
char c;
if (loop <= 0)
@ -36,8 +38,18 @@ readname_loop(char *packet, char **src, char *dst, size_t length, size_t loop)
/* is this a compressed label? */
if((c & 0xc0) == 0xc0) {
dummy = packet + (((s[-1] & 0x3f) << 8) | s[0]);
len += readname_loop(packet, &dummy, d, length - len, loop - 1);
offset = (((s[-1] & 0x3f) << 8) | s[0]);
if (offset > packetlen) {
if (len == 0) {
// Bad jump first in packet
return 0;
} else {
// Bad jump after some data
break;
}
}
dummy = packet + offset;
len += readname_loop(packet, packetlen, &dummy, d, length - len, loop - 1);
goto end;
}
@ -65,9 +77,9 @@ end:
}
int
readname(char *packet, char **src, char *dst, size_t length)
readname(char *packet, int packetlen, char **src, char *dst, size_t length)
{
return readname_loop(packet, src, dst, length, 10);
return readname_loop(packet, packetlen, src, dst, length, 10);
}
int

2
read.h
View File

@ -17,7 +17,7 @@
#ifndef _READ_H_
#define _READ_H_
int readname(char *, char **, char *, size_t);
int readname(char *, int, char **, char *, size_t);
int readshort(char *, char **, short *);
int readlong(char *, char **, long *);
int readdata(char *, char **, char *, size_t);

36
test.c
View File

@ -129,6 +129,13 @@ test_readname()
char onejump[] =
"AA\x81\x80\x00\x01\x00\x00\x00\x00\x00\x00"
"\x02hh\xc0\x15\x00\x01\x00\x01\x05zBCDE\x00";
char badjump[] = {
'A', 'A', 0x81, 0x80, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0xfe, 0xcc, 0x00, 0x01, 0x00, 0x01 };
char badjump2[] = {
'A', 'A', 0x81, 0x80, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x02, 'B', 'A', 0xfe, 0xcc, 0x00, 0x01, 0x00, 0x01 };
char *jumper;
char buf[1024];
char *data;
int rv;
@ -139,25 +146,46 @@ test_readname()
bzero(buf, sizeof(buf));
data = emptyloop + sizeof(HEADER);
buf[1023] = 'A';
rv = readname(emptyloop, &data, buf, 1023);
rv = readname(emptyloop, sizeof(emptyloop), &data, buf, 1023);
assert(buf[1023] == 'A');
bzero(buf, sizeof(buf));
data = infloop + sizeof(HEADER);
buf[4] = '\a';
rv = readname(infloop, &data, buf, 4);
rv = readname(infloop, sizeof(infloop), &data, buf, 4);
assert(buf[4] == '\a');
bzero(buf, sizeof(buf));
data = longname + sizeof(HEADER);
buf[256] = '\a';
rv = readname(longname, &data, buf, 256);
rv = readname(longname, sizeof(longname), &data, buf, 256);
assert(buf[256] == '\a');
bzero(buf, sizeof(buf));
data = onejump + sizeof(HEADER);
rv = readname(onejump, &data, buf, 256);
rv = readname(onejump, sizeof(onejump), &data, buf, 256);
assert(rv == 9);
// These two tests use malloc to fail with segfault if jump is executed
bzero(buf, sizeof(buf));
jumper = malloc(sizeof(badjump));
if (jumper) {
memcpy(jumper, badjump, sizeof(badjump));
data = jumper + sizeof(HEADER);
rv = readname(jumper, sizeof(badjump), &data, buf, 256);
assert(rv == 0);
}
free(jumper);
bzero(buf, sizeof(buf));
jumper = malloc(sizeof(badjump2));
if (jumper) {
memcpy(jumper, badjump2, sizeof(badjump2));
data = jumper + sizeof(HEADER);
rv = readname(jumper, sizeof(badjump2), &data, buf, 256);
assert(rv == 4);
}
free(jumper);
printf("OK\n");
}