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Merge branch 'ipv6' into masterv6
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@ValdikSS
ValdikSS committed Feb 16, 2018
2 parents aa28d3e + 860f483 commit 185a0e0
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Showing 3 changed files with 321 additions and 111 deletions.
98 changes: 71 additions & 27 deletions dnsredir.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -17,8 +17,8 @@
#include "dnsredir.h"
#include "uthash.h"

// IPv6 incompatible!
#define UDP_CONNRECORD_KEY_LEN 6
/* key ('4' for IPv4 or '6' for IPv6 + srcip[16] + srcport[2]) */
#define UDP_CONNRECORD_KEY_LEN 19

#define DNS_CLEANUP_INTERVAL_SEC 30

Expand All @@ -32,10 +32,10 @@
#define uthash_strlen(s) UDP_CONNRECORD_KEY_LEN

typedef struct udp_connrecord {
/* key (srcip[4] + srcport[2]) */
/* key ('4' for IPv4 or '6' for IPv6 + srcip[16] + srcport[2]) */
char key[UDP_CONNRECORD_KEY_LEN];
time_t time; /* time when this record was added */
uint32_t dstip;
uint32_t dstip[4];
uint16_t dstport;
UT_hash_handle hh; /* makes this structure hashable */
} udp_connrecord_t;
Expand All @@ -59,26 +59,60 @@ void flush_dns_cache() {
FreeLibrary(dnsapi);
}

inline static void construct_key(const uint32_t srcip, const uint16_t srcport, char *key) {
inline static void fill_key_data(char *key, const uint8_t is_ipv6, const uint32_t srcip[4],
const uint16_t srcport)
{
if (is_ipv6) {
*(uint8_t*)(key) = '6';
ipv6_copy_addr((uint32_t*)(key + sizeof(uint8_t)), srcip);
}
else {
*(uint8_t*)(key) = '4';
ipv4_copy_addr((uint32_t*)(key + sizeof(uint8_t)), srcip);
}

*(uint16_t*)(key + sizeof(uint8_t) + sizeof(uint32_t) * 4) = srcport;
}

inline static void fill_data_from_key(uint8_t *is_ipv6, uint32_t srcip[4], uint16_t *srcport,
const char *key)
{
if (key[0] == '6') {
*is_ipv6 = 1;
ipv6_copy_addr(srcip, (uint32_t*)(key + sizeof(uint8_t)));
}
else {
*is_ipv6 = 0;
ipv4_copy_addr(srcip, (uint32_t*)(key + sizeof(uint8_t)));
}
*srcport = *(uint16_t*)(key + sizeof(uint8_t) + sizeof(uint32_t) * 4);
}

inline static void construct_key(const uint32_t srcip[4], const uint16_t srcport,
char *key, int is_ipv6)
{
debug("Construct key enter\n");
if (key) {
debug("Constructing key\n");

*(uint32_t*)(key) = srcip;
*(uint16_t*)(key + sizeof(srcip)) = srcport;
fill_key_data(key, is_ipv6, srcip, srcport);
}
debug("Construct key end\n");
}

inline static void deconstruct_key(const char *key, udp_connrecord_t *connrecord,
conntrack_info_t *conn_info) {
inline static void deconstruct_key(const char *key, const udp_connrecord_t *connrecord,
conntrack_info_t *conn_info)
{
debug("Deconstruct key enter\n");
if (key && conn_info) {
debug("Deconstructing key\n");
fill_data_from_key(&conn_info->is_ipv6, conn_info->srcip,
&conn_info->srcport, key);

if (conn_info->is_ipv6)
ipv6_copy_addr(conn_info->dstip, connrecord->dstip);
else
ipv4_copy_addr(conn_info->dstip, connrecord->dstip);

conn_info->srcip = *(uint32_t*)(key);
conn_info->srcport = *(uint16_t*)(key + sizeof(conn_info->srcip));
conn_info->dstip = connrecord->dstip;
conn_info->dstport = connrecord->dstport;
}
debug("Deconstruct key end\n");
Expand All @@ -99,17 +133,26 @@ static int check_get_udp_conntrack_key(const char *key, udp_connrecord_t **connr
return FALSE;
}

static int add_udp_conntrack(const uint32_t srcip, const uint16_t srcport,
const uint32_t dstip, const uint16_t dstport) {
static int add_udp_conntrack(const uint32_t srcip[4], const uint16_t srcport,
const uint32_t dstip[4], const uint16_t dstport,
const int is_ipv6
)
{
if (!(srcip && srcport && dstip && dstport))
return FALSE;

udp_connrecord_t *tmp_connrecord = malloc(sizeof(udp_connrecord_t));
construct_key(srcip, srcport, tmp_connrecord->key);
construct_key(srcip, srcport, tmp_connrecord->key, is_ipv6);

if (!check_get_udp_conntrack_key(tmp_connrecord->key, NULL)) {
tmp_connrecord->time = time(NULL);
tmp_connrecord->dstip = dstip;

if (is_ipv6) {
ipv6_copy_addr(tmp_connrecord->dstip, dstip);
}
else {
ipv4_copy_addr(tmp_connrecord->dstip, dstip);
}
tmp_connrecord->dstport = dstport;
HASH_ADD_STR(conntrack, key, tmp_connrecord);
debug("Added UDP conntrack\n");
Expand All @@ -120,7 +163,7 @@ static int add_udp_conntrack(const uint32_t srcip, const uint16_t srcport,
return FALSE;
}

void dns_cleanup() {
static void dns_cleanup() {
udp_connrecord_t *tmp_connrecord, *tmp_connrecord2 = NULL;

if (last_cleanup == 0) {
Expand Down Expand Up @@ -154,10 +197,11 @@ int dns_is_dns_packet(const char *packet_data, const UINT packet_dataLen, const
return FALSE;
}

int dns_handle_outgoing(const uint32_t srcip, const uint16_t srcport,
const uint32_t dstip, const uint16_t dstport,
const char *packet_data, const UINT packet_dataLen) {

int dns_handle_outgoing(const uint32_t srcip[4], const uint16_t srcport,
const uint32_t dstip[4], const uint16_t dstport,
const char *packet_data, const UINT packet_dataLen,
const uint8_t is_ipv6)
{
if (packet_dataLen < 16)
return FALSE;

Expand All @@ -166,16 +210,16 @@ int dns_handle_outgoing(const uint32_t srcip, const uint16_t srcport,
if (dns_is_dns_packet(packet_data, packet_dataLen, 1)) {
/* Looks like DNS request */
debug("trying to add srcport = %hu, dstport = %hu\n", ntohs(srcport), ntohs(dstport));
return add_udp_conntrack(srcip, srcport, dstip, dstport);
return add_udp_conntrack(srcip, srcport, dstip, dstport, is_ipv6);
}
debug("____dns_handle_outgoing FALSE: srcport = %hu, dstport = %hu\n", ntohs(srcport), ntohs(dstport));
return FALSE;
}

int dns_handle_incoming(const uint32_t srcip, const uint16_t srcport,
int dns_handle_incoming(const uint32_t srcip[4], const uint16_t srcport,
const char *packet_data, const UINT packet_dataLen,
conntrack_info_t *conn_info) {

conntrack_info_t *conn_info, const uint8_t is_ipv6)
{
char key[UDP_CONNRECORD_KEY_LEN];
udp_connrecord_t *tmp_connrecord = NULL;

Expand All @@ -186,7 +230,7 @@ int dns_handle_incoming(const uint32_t srcip, const uint16_t srcport,

if (dns_is_dns_packet(packet_data, packet_dataLen, 0)) {
/* Looks like DNS response */
construct_key(srcip, srcport, key);
construct_key(srcip, srcport, key, is_ipv6);
if (check_get_udp_conntrack_key(key, &tmp_connrecord) && tmp_connrecord) {
/* Connection exists in conntrack, moving on */
deconstruct_key(key, tmp_connrecord, conn_info);
Expand Down
31 changes: 24 additions & 7 deletions dnsredir.h
View file
Original file line number Diff line number Diff line change
@@ -1,19 +1,36 @@
#include <stdint.h>

typedef struct conntrack_info {
uint32_t srcip;
uint8_t is_ipv6;
uint32_t srcip[4];
uint16_t srcport;
uint32_t dstip;
uint32_t dstip[4];
uint16_t dstport;
} conntrack_info_t;

int dns_handle_incoming(const uint32_t srcip, const uint16_t srcport,
inline static void ipv4_copy_addr(uint32_t dst[4], const uint32_t src[4]) {
dst[0] = src[0];
dst[1] = 0;
dst[2] = 0;
dst[3] = 0;
}

inline static void ipv6_copy_addr(uint32_t dst[4], const uint32_t src[4]) {
dst[0] = src[0];
dst[1] = src[1];
dst[2] = src[2];
dst[3] = src[3];
}

int dns_handle_incoming(const uint32_t srcip[4], const uint16_t srcport,
const char *packet_data, const UINT packet_dataLen,
conntrack_info_t *conn_info);
conntrack_info_t *conn_info, const uint8_t is_ipv6);

int dns_handle_outgoing(const uint32_t srcip, const uint16_t srcport,
const uint32_t dstip, const uint16_t dstport,
const char *packet_data, const UINT packet_dataLen);
int dns_handle_outgoing(const uint32_t srcip[4], const uint16_t srcport,
const uint32_t dstip[4], const uint16_t dstport,
const char *packet_data, const UINT packet_dataLen,
const uint8_t is_ipv6
);

void flush_dns_cache();
int dns_is_dns_packet(const char *packet_data, const UINT packet_dataLen, const int outgoing);
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