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https://github.com/bol-van/zapret.git
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109 lines
4.2 KiB
C
109 lines
4.2 KiB
C
#pragma once
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// this conntrack is not bullet-proof
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// its designed to satisfy dpi desync needs only
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#include <stdbool.h>
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#include <stdint.h>
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#include <ctype.h>
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#include <sys/types.h>
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#include <time.h>
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#include <netinet/in.h>
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#include <netinet/ip.h>
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#include <netinet/ip6.h>
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#include <netinet/tcp.h>
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#include <netinet/udp.h>
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//#define HASH_BLOOM 20
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#define HASH_NONFATAL_OOM 1
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#undef HASH_FUNCTION
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#define HASH_FUNCTION HASH_BER
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#include "uthash.h"
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#define RETRANS_COUNTER_STOP ((uint8_t)-1)
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typedef union {
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struct in_addr ip;
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struct in6_addr ip6;
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} t_addr;
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typedef struct
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{
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t_addr src, dst;
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uint16_t sport,dport;
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uint8_t l3proto; // IPPROTO_IP, IPPROTO_IPV6
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uint8_t l4proto; // IPPROTO_TCP, IPPROTO_UDP
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} t_conn;
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// this structure helps to reassemble continuous packets streams. it does not support out-of-orders
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typedef struct {
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uint8_t *packet; // allocated for size during reassemble request. requestor must know the message size.
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uint32_t seq; // current seq number. if a packet comes with an unexpected seq - it fails reassemble session.
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size_t size; // expected message size. success means that we have received exactly 'size' bytes and have them in 'packet'
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size_t size_present; // how many bytes already stored in 'packet'
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} t_reassemble;
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// SYN - SYN or SYN/ACK received
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// ESTABLISHED - any except SYN or SYN/ACK received
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// FIN - FIN or RST received
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typedef enum {SYN=0, ESTABLISHED, FIN} t_connstate;
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typedef enum {UNKNOWN=0, HTTP, TLS, QUIC, WIREGUARD, DHT} t_l7proto;
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typedef struct
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{
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// common state
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time_t t_start, t_last;
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uint64_t pcounter_orig, pcounter_reply; // packet counter
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uint64_t pdcounter_orig, pdcounter_reply; // data packet counter (with payload)
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uint32_t pos_orig, pos_reply; // TCP: seq_last+payload, ack_last+payload UDP: sum of all seen payload lenghts including current
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uint32_t seq_last, ack_last; // TCP: last seen seq and ack UDP: sum of all seen payload lenghts NOT including current
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// tcp only state, not used in udp
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t_connstate state;
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uint32_t seq0, ack0; // starting seq and ack
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uint16_t winsize_orig, winsize_reply; // last seen window size
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uint8_t scale_orig, scale_reply; // last seen window scale factor. SCALE_NONE if none
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uint8_t req_retrans_counter; // number of request retransmissions
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bool req_seq_start_present, req_seq_present;
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uint32_t req_seq_start,req_seq_end; // sequence interval of the request (to track retransmissions)
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uint8_t autottl;
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bool b_cutoff; // mark for deletion
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bool b_wssize_cutoff, b_desync_cutoff;
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t_reassemble reasm_orig;
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t_l7proto l7proto;
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char *hostname;
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} t_ctrack;
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typedef struct
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{
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t_ctrack track;
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UT_hash_handle hh; // makes this structure hashable
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t_conn conn; // key
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} t_conntrack_pool;
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typedef struct
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{
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// inactivity time to purge an entry in each connection state
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uint32_t timeout_syn,timeout_established,timeout_fin,timeout_udp;
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time_t t_purge_interval, t_last_purge;
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t_conntrack_pool *pool;
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} t_conntrack;
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void ConntrackPoolInit(t_conntrack *p, time_t purge_interval, uint32_t timeout_syn, uint32_t timeout_established, uint32_t timeout_fin, uint32_t timeout_udp);
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void ConntrackPoolDestroy(t_conntrack *p);
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bool ConntrackPoolFeed(t_conntrack *p, const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcphdr, const struct udphdr *udphdr, size_t len_payload, t_ctrack **ctrack, bool *bReverse);
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bool ConntrackPoolDrop(t_conntrack *p, const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcphdr, const struct udphdr *udphdr);
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void CaonntrackExtractConn(t_conn *c, bool bReverse, const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcphdr, const struct udphdr *udphdr);
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void ConntrackPoolDump(const t_conntrack *p);
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void ConntrackPoolPurge(t_conntrack *p);
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void ConntrackClearHostname(t_ctrack *track);
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bool ReasmInit(t_reassemble *reasm, size_t size_requested, uint32_t seq_start);
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void ReasmClear(t_reassemble *reasm);
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// false means reassemble session has failed and we should ReasmClear() it
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bool ReasmFeed(t_reassemble *reasm, uint32_t seq, const void *payload, size_t len);
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inline static bool ReasmIsEmpty(t_reassemble *reasm) {return !reasm->size;}
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inline static bool ReasmIsFull(t_reassemble *reasm) {return !ReasmIsEmpty(reasm) && (reasm->size==reasm->size_present);}
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