zapret/nfq/conntrack.h

97 lines
2.7 KiB
C

#pragma once
// this conntrack is not bullet-proof
// its designed to satisfy dpi desync needs only
#include <stdbool.h>
#include <stdint.h>
#include <ctype.h>
#include <sys/types.h>
#include <time.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/tcp.h>
//#define HASH_BLOOM 20
#define HASH_NONFATAL_OOM 1
#undef HASH_FUNCTION
#define HASH_FUNCTION HASH_BER
#include "uthash.h"
typedef struct
{
struct in_addr adr;
uint16_t port;
} t_endpoint4;
typedef struct
{
struct in6_addr adr;
uint16_t port;
} t_endpoint6;
// e1 - initiator. the one who have sent SYN
// e2 - acceptor
typedef struct
{
t_endpoint4 e1,e2;
} t_conn4;
typedef struct
{
t_endpoint6 e1,e2;
} t_conn6;
// SYN - SYN or SYN/ACK received
// ESTABLISHED - any except SYN or SYN/ACK received
// FIN - FIN or RST received
typedef enum {SYN=0, ESTABLISHED, FIN} t_connstate;
typedef struct
{
t_connstate state;
time_t t_start, t_last;
uint32_t seq0, ack0; // starting seq and ack
uint32_t seq_last, ack_last; // current seq and ack
uint64_t pcounter_orig, pcounter_reply; // packet counter
uint16_t winsize_orig, winsize_reply; // last seen window size
uint8_t scale_orig, scale_reply; // last seen window scale factor. SCALE_NONE if none
bool b_cutoff; // mark for deletion
bool b_wssize_cutoff, b_desync_cutoff;
} t_ctrack;
// use separate pools for ipv4 and ipv6 to save RAM. otherwise could use union key
typedef struct
{
t_ctrack track;
UT_hash_handle hh; // makes this structure hashable
t_conn4 conn; // key
} t_conntrack4;
typedef struct
{
t_ctrack track;
UT_hash_handle hh; // makes this structure hashable
t_conn6 conn; // key
} t_conntrack6;
typedef struct
{
// inactivity time to purge an entry in each connection state
uint32_t timeout_syn,timeout_established,timeout_fin;
time_t t_purge_interval, t_last_purge;
t_conntrack4 *pool4;
t_conntrack6 *pool6;
} t_conntrack;
void ConntrackPoolInit(t_conntrack *p, time_t purge_interval, uint32_t timeout_syn, uint32_t timeout_established, uint32_t timeout_fin);
void ConntrackPoolDestroy(t_conntrack *p);
bool ConntrackPoolFeed(t_conntrack *p, const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcphdr, size_t len_payload, t_ctrack **ctrack, bool *bReverse);
bool ConntrackPoolDrop(t_conntrack *p, const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcphdr);
void ConntrackExtractConn4(t_conn4 *c, bool bReverse, const struct ip *ip, const struct tcphdr *tcphdr);
void ConntrackExtractConn6(t_conn6 *c, bool bReverse, const struct ip6_hdr *ip, const struct tcphdr *tcphdr);
void ConntrackPoolDump4(t_conntrack4 *p);
void ConntrackPoolDump6(t_conntrack6 *p);
void ConntrackPoolDump(t_conntrack *p);
void ConntrackPoolPurge(t_conntrack *p);