mirror of
https://github.com/bol-van/zapret.git
synced 2024-11-30 05:50:53 +03:00
1297 lines
47 KiB
C
1297 lines
47 KiB
C
#define _GNU_SOURCE
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#include "desync.h"
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#include "protocol.h"
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#include "params.h"
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#include "helpers.h"
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#include "hostlist.h"
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#include "conntrack.h"
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#include <string.h>
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const char *fake_http_request_default = "GET / HTTP/1.1\r\nHost: www.iana.org\r\n"
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"User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/109.0\r\n"
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"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8\r\n"
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"Accept-Encoding: gzip, deflate, br\r\n\r\n";
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const uint8_t fake_tls_clienthello_default[517] = {
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0x16, 0x03, 0x01, 0x02, 0x00, 0x01, 0x00, 0x01, 0xFC, 0x03, 0x03, 0x6F, 0x0B, 0xB6, 0x85, 0x58, 0x28, 0x59, 0xD5, 0x0D, 0x6C, 0x78, 0x39, 0x7F, 0x2B, 0x0B, 0x45, 0xA3, 0x71, 0x4F, 0x49, 0xD6, 0x34, 0x17, 0xC6, 0x59, 0xA5, 0x1D, 0x89, 0x01,
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0xE1, 0x72, 0x1D, 0x20, 0x9D, 0x2C, 0xAB, 0x26, 0x58, 0xA7, 0x83, 0xBF, 0xB7, 0xDC, 0x5F, 0x28, 0xAA, 0x11, 0xA7, 0x63, 0x54, 0x19, 0xCB, 0xC6, 0xC4, 0x0E, 0xA4, 0x15, 0x46, 0xCC, 0x2F, 0x25, 0x13, 0x9A, 0x14, 0x54, 0x00, 0x3E, 0x13, 0x02,
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0x13, 0x03, 0x13, 0x01, 0xC0, 0x2C, 0xC0, 0x30, 0x00, 0x9F, 0xCC, 0xA9, 0xCC, 0xA8, 0xCC, 0xAA, 0xC0, 0x2B, 0xC0, 0x2F, 0x00, 0x9E, 0xC0, 0x24, 0xC0, 0x28, 0x00, 0x6B, 0xC0, 0x23, 0xC0, 0x27, 0x00, 0x67, 0xC0, 0x0A, 0xC0, 0x14, 0x00, 0x39,
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0xC0, 0x09, 0xC0, 0x13, 0x00, 0x33, 0x00, 0x9D, 0x00, 0x9C, 0x00, 0x3D, 0x00, 0x3C, 0x00, 0x35, 0x00, 0x2F, 0x00, 0xFF, 0x01, 0x00, 0x01, 0x75, 0x00, 0x00, 0x00, 0x0D, 0x00, 0x0B, 0x00, 0x00, 0x08, 0x69, 0x61, 0x6E, 0x61, 0x2E, 0x6F, 0x72,
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0x67, 0x00, 0x0B, 0x00, 0x04, 0x03, 0x00, 0x01, 0x02, 0x00, 0x0A, 0x00, 0x0C, 0x00, 0x0A, 0x00, 0x1D, 0x00, 0x17, 0x00, 0x1E, 0x00, 0x19, 0x00, 0x18, 0x33, 0x74, 0x00, 0x00, 0x00, 0x10, 0x00, 0x0E, 0x00, 0x0C, 0x02, 0x68, 0x32, 0x08, 0x68,
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0x74, 0x74, 0x70, 0x2F, 0x31, 0x2E, 0x31, 0x00, 0x16, 0x00, 0x00, 0x00, 0x17, 0x00, 0x00, 0x00, 0x31, 0x00, 0x00, 0x00, 0x0D, 0x00, 0x30, 0x00, 0x2E, 0x04, 0x03, 0x05, 0x03, 0x06, 0x03, 0x08, 0x07, 0x08, 0x08, 0x08, 0x09, 0x08, 0x0A, 0x08,
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0x0B, 0x08, 0x04, 0x08, 0x05, 0x08, 0x06, 0x04, 0x01, 0x05, 0x01, 0x06, 0x01, 0x03, 0x03, 0x02, 0x03, 0x03, 0x01, 0x02, 0x01, 0x03, 0x02, 0x02, 0x02, 0x04, 0x02, 0x05, 0x02, 0x06, 0x02, 0x00, 0x2B, 0x00, 0x09, 0x08, 0x03, 0x04, 0x03, 0x03,
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0x03, 0x02, 0x03, 0x01, 0x00, 0x2D, 0x00, 0x02, 0x01, 0x01, 0x00, 0x33, 0x00, 0x26, 0x00, 0x24, 0x00, 0x1D, 0x00, 0x20, 0x1B, 0xB3, 0xF5, 0x23, 0x6E, 0x05, 0x98, 0x5D, 0x92, 0x30, 0x8A, 0xAC, 0x64, 0x61, 0x1F, 0xD7, 0x0A, 0x6D, 0xB1, 0xA5,
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0x74, 0xF9, 0x44, 0x07, 0xC0, 0x55, 0xD8, 0x8B, 0x0C, 0xEA, 0x29, 0x27, 0x00, 0x15, 0x00, 0xB5, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
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};
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#define PKTDATA_MAXDUMP 32
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#define IP_MAXDUMP 80
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static uint8_t zeropkt[DPI_DESYNC_MAX_FAKE_LEN];
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void desync_init(void)
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{
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memset(zeropkt, 0, sizeof(zeropkt));
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}
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bool desync_valid_zero_stage(enum dpi_desync_mode mode)
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{
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return mode==DESYNC_SYNACK || mode==DESYNC_SYNDATA;
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}
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bool desync_valid_first_stage(enum dpi_desync_mode mode)
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{
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return mode==DESYNC_FAKE || mode==DESYNC_FAKE_KNOWN || mode==DESYNC_RST || mode==DESYNC_RSTACK || mode==DESYNC_HOPBYHOP || mode==DESYNC_DESTOPT || mode==DESYNC_IPFRAG1;
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}
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bool desync_only_first_stage(enum dpi_desync_mode mode)
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{
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return false;
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}
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bool desync_valid_second_stage(enum dpi_desync_mode mode)
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{
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return mode==DESYNC_NONE || mode==DESYNC_DISORDER || mode==DESYNC_DISORDER2 || mode==DESYNC_SPLIT || mode==DESYNC_SPLIT2 || mode==DESYNC_IPFRAG2 || mode==DESYNC_UDPLEN || mode==DESYNC_TAMPER;
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}
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bool desync_valid_second_stage_tcp(enum dpi_desync_mode mode)
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{
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return mode==DESYNC_NONE || mode==DESYNC_DISORDER || mode==DESYNC_DISORDER2 || mode==DESYNC_SPLIT || mode==DESYNC_SPLIT2 || mode==DESYNC_IPFRAG2;
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}
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bool desync_valid_second_stage_udp(enum dpi_desync_mode mode)
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{
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return mode==DESYNC_NONE || mode==DESYNC_UDPLEN || mode==DESYNC_TAMPER || mode==DESYNC_IPFRAG2;
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}
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enum dpi_desync_mode desync_mode_from_string(const char *s)
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{
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if (!s)
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return DESYNC_NONE;
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else if (!strcmp(s,"fake"))
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return DESYNC_FAKE;
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else if (!strcmp(s,"fakeknown"))
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return DESYNC_FAKE_KNOWN;
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else if (!strcmp(s,"rst"))
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return DESYNC_RST;
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else if (!strcmp(s,"rstack"))
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return DESYNC_RSTACK;
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else if (!strcmp(s,"synack"))
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return DESYNC_SYNACK;
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else if (!strcmp(s,"syndata"))
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return DESYNC_SYNDATA;
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else if (!strcmp(s,"disorder"))
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return DESYNC_DISORDER;
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else if (!strcmp(s,"disorder2"))
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return DESYNC_DISORDER2;
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else if (!strcmp(s,"split"))
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return DESYNC_SPLIT;
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else if (!strcmp(s,"split2"))
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return DESYNC_SPLIT2;
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else if (!strcmp(s,"ipfrag2"))
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return DESYNC_IPFRAG2;
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else if (!strcmp(s,"hopbyhop"))
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return DESYNC_HOPBYHOP;
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else if (!strcmp(s,"destopt"))
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return DESYNC_DESTOPT;
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else if (!strcmp(s,"ipfrag1"))
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return DESYNC_IPFRAG1;
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else if (!strcmp(s,"udplen"))
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return DESYNC_UDPLEN;
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else if (!strcmp(s,"tamper"))
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return DESYNC_TAMPER;
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return DESYNC_INVALID;
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}
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// auto creates internal socket and uses it for subsequent calls
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static bool rawsend_rep(const struct sockaddr* dst,uint32_t fwmark,const char *ifout,const void *data,size_t len)
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{
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for (int i=0;i<params.desync_repeats;i++)
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if (!rawsend(dst,fwmark,ifout,data,len))
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return false;
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return true;
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}
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static uint64_t cutoff_get_limit(t_ctrack *ctrack, char mode)
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{
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switch(mode)
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{
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case 'n': return ctrack->pcounter_orig;
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case 'd': return ctrack->pdcounter_orig;
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case 's': return ctrack->seq_last - ctrack->seq0;
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default: return 0;
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}
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}
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static bool cutoff_test(t_ctrack *ctrack, uint64_t cutoff, char mode)
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{
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return cutoff && cutoff_get_limit(ctrack, mode)>=cutoff;
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}
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static void maybe_cutoff(t_ctrack *ctrack, uint8_t proto)
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{
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if (ctrack)
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{
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if (proto==IPPROTO_TCP)
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ctrack->b_wssize_cutoff |= cutoff_test(ctrack, params.wssize_cutoff, params.wssize_cutoff_mode);
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ctrack->b_desync_cutoff |= cutoff_test(ctrack, params.desync_cutoff, params.desync_cutoff_mode);
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// we do not need conntrack entry anymore if all cutoff conditions are either not defined or reached
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// do not drop udp entry because it will be recreated when next packet arrives
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if (proto==IPPROTO_TCP)
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ctrack->b_cutoff |= \
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(!params.wssize || ctrack->b_wssize_cutoff) &&
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(!params.desync_cutoff || ctrack->b_desync_cutoff) &&
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(!*params.hostlist_auto_filename || ctrack->req_retrans_counter==RETRANS_COUNTER_STOP) &&
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ReasmIsEmpty(&ctrack->reasm_orig);
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}
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}
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static void wssize_cutoff(t_ctrack *ctrack)
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{
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if (ctrack)
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{
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ctrack->b_wssize_cutoff = true;
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maybe_cutoff(ctrack, IPPROTO_TCP);
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}
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}
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static void forced_wssize_cutoff(t_ctrack *ctrack)
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{
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if (ctrack && params.wssize && !ctrack->b_wssize_cutoff)
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{
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DLOG("forced wssize-cutoff\n");
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wssize_cutoff(ctrack);
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}
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}
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static void ctrack_stop_retrans_counter(t_ctrack *ctrack)
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{
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if (ctrack && *params.hostlist_auto_filename)
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{
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ctrack->req_retrans_counter = RETRANS_COUNTER_STOP;
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maybe_cutoff(ctrack, IPPROTO_TCP);
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}
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}
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// return true if retrans trigger fires
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static bool auto_hostlist_retrans(t_ctrack *ctrack, uint8_t l4proto, int threshold)
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{
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if (*params.hostlist_auto_filename && ctrack && ctrack->req_retrans_counter!=RETRANS_COUNTER_STOP)
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{
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if (l4proto==IPPROTO_TCP)
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{
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if (!ctrack->req_seq_present)
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return false;
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if (!seq_within(ctrack->seq_last, ctrack->req_seq_start, ctrack->req_seq_end))
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{
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DLOG("req retrans : tcp seq %u not within the req range %u-%u. stop tracking.\n", ctrack->seq_last, ctrack->req_seq_start, ctrack->req_seq_end);
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ctrack_stop_retrans_counter(ctrack);
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ctrack->req_seq_present = false;
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return false;
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}
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}
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ctrack->req_retrans_counter++;
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if (ctrack->req_retrans_counter >= threshold)
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{
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DLOG("req retrans threshold reached : %u/%u\n",ctrack->req_retrans_counter, threshold);
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ctrack_stop_retrans_counter(ctrack);
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return true;
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}
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DLOG("req retrans counter : %u/%u\n",ctrack->req_retrans_counter, threshold);
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}
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return false;
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}
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static void auto_hostlist_failed(const char *hostname)
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{
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hostfail_pool *fail_counter;
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fail_counter = HostFailPoolFind(params.hostlist_auto_fail_counters, hostname);
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if (!fail_counter)
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{
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fail_counter = HostFailPoolAdd(¶ms.hostlist_auto_fail_counters, hostname, params.hostlist_auto_fail_time);
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if (!fail_counter)
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{
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fprintf(stderr, "HostFailPoolAdd: out of memory\n");
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return;
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}
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}
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fail_counter->counter++;
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DLOG("auto hostlist : %s : fail counter %d/%d\n", hostname, fail_counter->counter, params.hostlist_auto_fail_threshold);
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HOSTLIST_DEBUGLOG_APPEND("%s : fail counter %d/%d", hostname, fail_counter->counter, params.hostlist_auto_fail_threshold);
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if (fail_counter->counter >= params.hostlist_auto_fail_threshold)
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{
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DLOG("auto hostlist : fail threshold reached. about to add %s to auto hostlist\n", hostname);
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HostFailPoolDel(¶ms.hostlist_auto_fail_counters, fail_counter);
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DLOG("auto hostlist : rechecking %s to avoid duplicates\n", hostname);
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bool bExcluded=false;
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if (!HostlistCheck(hostname, &bExcluded) && !bExcluded)
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{
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DLOG("auto hostlist : adding %s\n", hostname);
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HOSTLIST_DEBUGLOG_APPEND("%s : adding", hostname);
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if (!StrPoolAddStr(¶ms.hostlist, hostname))
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{
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fprintf(stderr, "StrPoolAddStr out of memory\n");
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return;
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}
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if (!append_to_list_file(params.hostlist_auto_filename, hostname))
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{
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perror("write to auto hostlist:");
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return;
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}
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params.hostlist_auto_mod_time = file_mod_time(params.hostlist_auto_filename);
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}
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else
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{
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DLOG("auto hostlist : NOT adding %s\n", hostname);
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HOSTLIST_DEBUGLOG_APPEND("%s : NOT adding, duplicate detected", hostname);
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}
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}
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}
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static void process_retrans_fail(t_ctrack *ctrack, uint8_t proto)
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{
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if (ctrack && ctrack->hostname && auto_hostlist_retrans(ctrack, proto, params.hostlist_auto_retrans_threshold))
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{
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HOSTLIST_DEBUGLOG_APPEND("%s : tcp retrans threshold reached", ctrack->hostname);
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auto_hostlist_failed(ctrack->hostname);
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}
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}
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static bool reasm_start(t_ctrack *ctrack, t_reassemble *reasm, size_t sz, size_t szMax, const uint8_t *data_payload, size_t len_payload)
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{
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ReasmClear(reasm);
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if (sz<=szMax)
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{
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if (ReasmInit(reasm,sz,ctrack->seq_last))
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{
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ReasmFeed(reasm,ctrack->seq_last,data_payload,len_payload);
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DLOG("starting reassemble. now we have %zu/%zu\n",reasm->size_present,reasm->size);
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return true;
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}
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else
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DLOG("reassemble init failed. out of memory\n");
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}
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else
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DLOG("unexpected large payload for reassemble: size=%zu\n",sz);
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return false;
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}
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static bool reasm_orig_start(t_ctrack *ctrack, size_t sz, size_t szMax, const uint8_t *data_payload, size_t len_payload)
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{
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return reasm_start(ctrack,&ctrack->reasm_orig,sz,szMax,data_payload,len_payload);
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}
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static bool reasm_feed(t_ctrack *ctrack, t_reassemble *reasm, const uint8_t *data_payload, size_t len_payload)
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{
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if (ctrack && !ReasmIsEmpty(reasm))
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{
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if (ReasmFeed(reasm,ctrack->seq_last,data_payload,len_payload))
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{
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DLOG("reassemble : feeding data payload size=%zu. now we have %zu/%zu\n",len_payload,reasm->size_present,reasm->size)
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return true;
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}
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else
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{
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ReasmClear(reasm);
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DLOG("reassemble session failed\n")
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}
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}
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return false;
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}
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static bool reasm_orig_feed(t_ctrack *ctrack, const uint8_t *data_payload, size_t len_payload)
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{
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return reasm_feed(ctrack, &ctrack->reasm_orig, data_payload, len_payload);
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}
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static void reasm_orig_fin(t_ctrack *ctrack)
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{
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if (ctrack && ReasmIsFull(&ctrack->reasm_orig))
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{
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DLOG("reassemble session finished\n");
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ReasmClear(&ctrack->reasm_orig);
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}
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}
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static uint8_t ct_new_postnat_fix(const t_ctrack *ctrack, struct ip *ip, struct ip6_hdr *ip6, uint8_t proto, struct udphdr *udp, struct tcphdr *tcp, size_t *len_pkt)
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{
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#ifdef __linux__
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// if used in postnat chain, dropping initial packet will cause conntrack connection teardown
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// so we need to workaround this.
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// we can't use low ttl because TCP/IP stack listens to ttl expired ICMPs and notify socket
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// we also can't use fooling because DPI would accept fooled packets
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if (ctrack && ctrack->pcounter_orig==1)
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{
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DLOG("applying linux postnat conntrack workaround\n")
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if (proto==IPPROTO_UDP && udp && len_pkt)
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{
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// make malformed udp packet with zero length and invalid checksum
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udp->len = 0; // invalid length. must be >=8
|
|
udp_fix_checksum(udp,sizeof(struct udphdr),ip,ip6);
|
|
udp->check ^= htons(0xBEAF);
|
|
// truncate packet
|
|
*len_pkt = (uint8_t*)udp - (ip ? (uint8_t*)ip : (uint8_t*)ip6) + sizeof(struct udphdr);
|
|
if (ip)
|
|
{
|
|
ip->ip_len = htons((uint16_t)*len_pkt);
|
|
ip4_fix_checksum(ip);
|
|
}
|
|
else if (ip6)
|
|
ip6->ip6_ctlun.ip6_un1.ip6_un1_plen = (uint16_t)htons(sizeof(struct udphdr));
|
|
}
|
|
else if (proto==IPPROTO_TCP && tcp)
|
|
{
|
|
// only SYN here is expected
|
|
// make flags invalid and also corrupt checksum
|
|
tcp->th_flags = 0;
|
|
}
|
|
if (ip) ip->ip_sum ^= htons(0xBEAF);
|
|
return VERDICT_MODIFY | VERDICT_NOCSUM;
|
|
}
|
|
#endif
|
|
return VERDICT_DROP;
|
|
}
|
|
|
|
static uint8_t ct_new_postnat_fix_tcp(const t_ctrack *ctrack, struct ip *ip, struct ip6_hdr *ip6, struct tcphdr *tcphdr)
|
|
{
|
|
return ct_new_postnat_fix(ctrack,ip,ip6,IPPROTO_TCP,NULL,tcphdr,NULL);
|
|
}
|
|
static uint8_t ct_new_postnat_fix_udp(const t_ctrack *ctrack, struct ip *ip, struct ip6_hdr *ip6, struct udphdr *udphdr, size_t *len_pkt)
|
|
{
|
|
return ct_new_postnat_fix(ctrack,ip,ip6,IPPROTO_UDP,udphdr,NULL,len_pkt);
|
|
}
|
|
|
|
|
|
|
|
// result : true - drop original packet, false = dont drop
|
|
uint8_t dpi_desync_tcp_packet(uint32_t fwmark, const char *ifout, uint8_t *data_pkt, size_t *len_pkt, struct ip *ip, struct ip6_hdr *ip6hdr, struct tcphdr *tcphdr, size_t len_tcp, uint8_t *data_payload, size_t len_payload)
|
|
{
|
|
uint8_t res=VERDICT_PASS;
|
|
t_ctrack *ctrack=NULL;
|
|
bool bReverse=false;
|
|
|
|
struct sockaddr_storage src, dst;
|
|
uint8_t pkt1[DPI_DESYNC_MAX_FAKE_LEN+100], pkt2[DPI_DESYNC_MAX_FAKE_LEN+100];
|
|
size_t pkt1_len, pkt2_len;
|
|
uint8_t ttl_orig,ttl_fake,flags_orig,scale_factor;
|
|
uint32_t *timestamps;
|
|
|
|
if (!!ip == !!ip6hdr) return res; // one and only one must be present
|
|
ttl_orig = ip ? ip->ip_ttl : ip6hdr->ip6_ctlun.ip6_un1.ip6_un1_hlim;
|
|
|
|
ConntrackPoolPurge(¶ms.conntrack);
|
|
if (ConntrackPoolFeed(¶ms.conntrack, ip, ip6hdr, tcphdr, NULL, len_payload, &ctrack, &bReverse))
|
|
maybe_cutoff(ctrack, IPPROTO_TCP);
|
|
HostFailPoolPurgeRateLimited(¶ms.hostlist_auto_fail_counters);
|
|
|
|
//ConntrackPoolDump(¶ms.conntrack);
|
|
|
|
if (params.wsize && tcp_synack_segment(tcphdr))
|
|
{
|
|
tcp_rewrite_winsize(tcphdr, params.wsize, params.wscale);
|
|
res=VERDICT_MODIFY;
|
|
}
|
|
|
|
if (bReverse)
|
|
{
|
|
if (ctrack && !ctrack->autottl && ctrack->pcounter_reply==1)
|
|
{
|
|
autottl *attl = ip ? ¶ms.desync_autottl : ¶ms.desync_autottl6;
|
|
if (AUTOTTL_ENABLED(*attl))
|
|
{
|
|
ctrack->autottl = autottl_guess(ttl_orig, attl);
|
|
if (ctrack->autottl)
|
|
DLOG("autottl: guessed %u\n",ctrack->autottl)
|
|
else
|
|
DLOG("autottl: could not guess\n")
|
|
}
|
|
}
|
|
|
|
// process reply packets for auto hostlist mode
|
|
// by looking at RSTs or HTTP replies we decide whether original request looks like DPI blocked
|
|
// we only process first-sequence replies. do not react to subsequent redirects or RSTs
|
|
if (*params.hostlist_auto_filename && ctrack && ctrack->hostname && (ctrack->ack_last-ctrack->ack0)==1)
|
|
{
|
|
bool bFail=false;
|
|
if (tcphdr->th_flags & TH_RST)
|
|
{
|
|
DLOG("incoming RST detected for hostname %s\n", ctrack->hostname);
|
|
HOSTLIST_DEBUGLOG_APPEND("%s : incoming RST", ctrack->hostname);
|
|
bFail = true;
|
|
}
|
|
else if (len_payload && ctrack->l7proto==HTTP)
|
|
{
|
|
if (IsHttpReply(data_payload,len_payload))
|
|
{
|
|
DLOG("incoming HTTP reply detected for hostname %s\n", ctrack->hostname);
|
|
bFail = HttpReplyLooksLikeDPIRedirect(data_payload, len_payload, ctrack->hostname);
|
|
if (bFail)
|
|
{
|
|
DLOG("redirect to another domain detected. possibly DPI redirect.\n")
|
|
HOSTLIST_DEBUGLOG_APPEND("%s : redirect to another domain", ctrack->hostname);
|
|
}
|
|
else
|
|
DLOG("local or in-domain redirect detected. it's not a DPI redirect.\n")
|
|
}
|
|
else
|
|
{
|
|
// received not http reply. do not monitor this connection anymore
|
|
DLOG("incoming unknown HTTP data detected for hostname %s\n", ctrack->hostname);
|
|
}
|
|
}
|
|
if (bFail)
|
|
auto_hostlist_failed(ctrack->hostname);
|
|
if (tcphdr->th_flags & TH_RST)
|
|
ConntrackClearHostname(ctrack); // do not react to further dup RSTs
|
|
}
|
|
|
|
return res; // nothing to do. do not waste cpu
|
|
}
|
|
|
|
uint32_t desync_fwmark = fwmark | params.desync_fwmark;
|
|
|
|
if (params.wssize)
|
|
{
|
|
if (ctrack)
|
|
{
|
|
if (ctrack->b_wssize_cutoff)
|
|
{
|
|
DLOG("not changing wssize. wssize-cutoff reached\n");
|
|
}
|
|
else
|
|
{
|
|
if (params.wssize_cutoff) DLOG("wssize-cutoff not reached (mode %c): %llu/%u\n", params.wssize_cutoff_mode, (unsigned long long)cutoff_get_limit(ctrack,params.wssize_cutoff_mode), params.wssize_cutoff);
|
|
tcp_rewrite_winsize(tcphdr, params.wssize, params.wsscale);
|
|
res=VERDICT_MODIFY;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
DLOG("not changing wssize. wssize is set but conntrack entry is missing\n");
|
|
}
|
|
}
|
|
|
|
if (params.desync_mode0!=DESYNC_NONE || params.desync_mode!=DESYNC_NONE) // save some cpu
|
|
{
|
|
ttl_fake = (ctrack && ctrack->autottl) ? ctrack->autottl : (ip6hdr ? (params.desync_ttl6 ? params.desync_ttl6 : ttl_orig) : (params.desync_ttl ? params.desync_ttl : ttl_orig));
|
|
flags_orig = *((uint8_t*)tcphdr+13);
|
|
scale_factor = tcp_find_scale_factor(tcphdr);
|
|
timestamps = tcp_find_timestamps(tcphdr);
|
|
|
|
extract_endpoints(ip, ip6hdr, tcphdr, NULL, &src, &dst);
|
|
}
|
|
|
|
if (tcp_syn_segment(tcphdr))
|
|
{
|
|
switch (params.desync_mode0)
|
|
{
|
|
case DESYNC_SYNACK:
|
|
pkt1_len = sizeof(pkt1);
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, TH_SYN|TH_ACK, tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_fake,params.desync_fooling_mode,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
NULL, 0, pkt1, &pkt1_len))
|
|
{
|
|
return res;
|
|
}
|
|
DLOG("sending fake SYNACK\n");
|
|
if (!rawsend_rep((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
break;
|
|
case DESYNC_SYNDATA:
|
|
// make sure we are not breaking TCP fast open
|
|
if (tcp_has_fastopen(tcphdr))
|
|
{
|
|
DLOG("received SYN with TCP fast open option. syndata desync is not applied.\n");
|
|
break;
|
|
}
|
|
if (len_payload)
|
|
{
|
|
DLOG("received SYN with data payload. syndata desync is not applied.\n");
|
|
break;
|
|
}
|
|
pkt1_len = sizeof(pkt1);
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_orig,0,0,0, params.fake_syndata,params.fake_syndata_size, pkt1,&pkt1_len))
|
|
{
|
|
return res;
|
|
}
|
|
DLOG("sending SYN with fake data : ");
|
|
hexdump_limited_dlog(params.fake_syndata,params.fake_syndata_size,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend_rep((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
|
|
res = ct_new_postnat_fix_tcp(ctrack, ip, ip6hdr, tcphdr);
|
|
break;
|
|
}
|
|
// can do nothing else with SYN packet
|
|
return res;
|
|
}
|
|
|
|
if (params.desync_cutoff)
|
|
{
|
|
if (ctrack)
|
|
{
|
|
if (ctrack->b_desync_cutoff)
|
|
{
|
|
DLOG("not desyncing. desync-cutoff reached (mode %c): %llu/%u\n", params.desync_cutoff_mode, (unsigned long long)cutoff_get_limit(ctrack,params.desync_cutoff_mode), params.desync_cutoff);
|
|
return res;
|
|
}
|
|
DLOG("desync-cutoff not reached (mode %c): %llu/%u\n", params.desync_cutoff_mode, (unsigned long long)cutoff_get_limit(ctrack,params.desync_cutoff_mode), params.desync_cutoff);
|
|
}
|
|
else
|
|
{
|
|
DLOG("not desyncing. desync-cutoff is set but conntrack entry is missing\n");
|
|
return res;
|
|
}
|
|
}
|
|
|
|
if (!params.wssize && params.desync_mode==DESYNC_NONE && !params.hostcase && !params.hostnospace && !params.domcase && !*params.hostlist_auto_filename) return res; // nothing to do. do not waste cpu
|
|
|
|
if (!(tcphdr->th_flags & TH_SYN) && len_payload)
|
|
{
|
|
const uint8_t *fake;
|
|
size_t fake_size;
|
|
char host[256];
|
|
bool bHaveHost=false;
|
|
bool bIsHttp;
|
|
bool bKnownProtocol = false;
|
|
uint8_t *p, *phost;
|
|
const uint8_t *rdata_payload = data_payload;
|
|
size_t rlen_payload = len_payload;
|
|
|
|
if (reasm_orig_feed(ctrack,data_payload,len_payload))
|
|
{
|
|
rdata_payload = ctrack->reasm_orig.packet;
|
|
rlen_payload = ctrack->reasm_orig.size_present;
|
|
}
|
|
|
|
if ((bIsHttp = IsHttp(rdata_payload,rlen_payload)))
|
|
{
|
|
DLOG("packet contains HTTP request\n")
|
|
if (ctrack && !ctrack->l7proto) ctrack->l7proto = HTTP;
|
|
forced_wssize_cutoff(ctrack);
|
|
fake = params.fake_http;
|
|
fake_size = params.fake_http_size;
|
|
if (params.hostlist || params.hostlist_exclude)
|
|
{
|
|
bHaveHost=HttpExtractHost(rdata_payload,rlen_payload,host,sizeof(host));
|
|
if (!bHaveHost)
|
|
{
|
|
DLOG("not applying tampering to HTTP without Host:\n")
|
|
process_retrans_fail(ctrack, IPPROTO_TCP);
|
|
reasm_orig_fin(ctrack);
|
|
return res;
|
|
}
|
|
}
|
|
if (ctrack)
|
|
{
|
|
// we do not reassemble http
|
|
if (!ctrack->req_seq_present)
|
|
{
|
|
ctrack->req_seq_start=ctrack->seq_last;
|
|
ctrack->req_seq_end=ctrack->pos_orig-1;
|
|
ctrack->req_seq_start_present=ctrack->req_seq_present=true;
|
|
DLOG("req retrans : tcp seq interval %u-%u\n",ctrack->req_seq_start,ctrack->req_seq_end);
|
|
}
|
|
}
|
|
bKnownProtocol = true;
|
|
}
|
|
else if (IsTLSClientHello(rdata_payload,rlen_payload,TLS_PARTIALS_ENABLE))
|
|
{
|
|
bool bReqFull = IsTLSRecordFull(rdata_payload,rlen_payload);
|
|
DLOG(bReqFull ? "packet contains full TLS ClientHello\n" : "packet contains partial TLS ClientHello\n")
|
|
fake = params.fake_tls;
|
|
fake_size = params.fake_tls_size;
|
|
bHaveHost=TLSHelloExtractHost(rdata_payload,rlen_payload,host,sizeof(host),TLS_PARTIALS_ENABLE);
|
|
if (ctrack)
|
|
{
|
|
if (!ctrack->l7proto) ctrack->l7proto = TLS;
|
|
if (!bReqFull && ReasmIsEmpty(&ctrack->reasm_orig))
|
|
// do not reconstruct unexpected large payload (they are feeding garbage ?)
|
|
reasm_orig_start(ctrack,TLSRecordLen(data_payload),4096,data_payload,len_payload);
|
|
if (!ctrack->req_seq_start_present)
|
|
{
|
|
// lower bound of request seq interval
|
|
ctrack->req_seq_start=ctrack->seq_last;
|
|
ctrack->req_seq_start_present=true;
|
|
}
|
|
if (!ctrack->req_seq_present && bReqFull)
|
|
{
|
|
// upper bound of request seq interval
|
|
ctrack->req_seq_end=ctrack->pos_orig-1;
|
|
ctrack->req_seq_present=ctrack->req_seq_start_present;
|
|
DLOG("req retrans : seq interval %u-%u\n",ctrack->req_seq_start,ctrack->req_seq_end);
|
|
}
|
|
}
|
|
if (bReqFull || !ctrack || ReasmIsEmpty(&ctrack->reasm_orig)) forced_wssize_cutoff(ctrack);
|
|
|
|
if (params.desync_skip_nosni && !bHaveHost)
|
|
{
|
|
DLOG("not applying tampering to TLS ClientHello without hostname in the SNI\n")
|
|
process_retrans_fail(ctrack, IPPROTO_TCP);
|
|
reasm_orig_fin(ctrack);
|
|
return res;
|
|
}
|
|
bKnownProtocol = true;
|
|
}
|
|
|
|
reasm_orig_fin(ctrack);
|
|
rdata_payload=NULL;
|
|
|
|
if (bHaveHost)
|
|
{
|
|
bool bExcluded;
|
|
DLOG("hostname: %s\n",host)
|
|
if ((params.hostlist || params.hostlist_exclude) && !HostlistCheck(host, &bExcluded))
|
|
{
|
|
DLOG("not applying tampering to this request\n")
|
|
if (ctrack)
|
|
{
|
|
if (!bExcluded && *params.hostlist_auto_filename)
|
|
{
|
|
if (!ctrack->hostname) ctrack->hostname=strdup(host);
|
|
process_retrans_fail(ctrack, IPPROTO_TCP);
|
|
}
|
|
else
|
|
ctrack_stop_retrans_counter(ctrack);
|
|
}
|
|
return res;
|
|
}
|
|
ctrack_stop_retrans_counter(ctrack);
|
|
}
|
|
process_retrans_fail(ctrack, IPPROTO_TCP);
|
|
|
|
if (!bKnownProtocol)
|
|
{
|
|
if (!params.desync_any_proto) return res;
|
|
DLOG("applying tampering to unknown protocol\n")
|
|
fake = params.fake_unknown;
|
|
fake_size = params.fake_unknown_size;
|
|
}
|
|
|
|
if (bIsHttp && (params.hostcase || params.hostnospace || params.domcase) && (phost = (uint8_t*)memmem(data_payload, len_payload, "\r\nHost: ", 8)))
|
|
{
|
|
if (params.hostcase)
|
|
{
|
|
DLOG("modifying Host: => %c%c%c%c:\n", params.hostspell[0], params.hostspell[1], params.hostspell[2], params.hostspell[3])
|
|
memcpy(phost + 2, params.hostspell, 4);
|
|
res=VERDICT_MODIFY;
|
|
}
|
|
if (params.domcase)
|
|
{
|
|
DLOG("mixing domain case\n");
|
|
for (p = phost+7; p < (data_payload + len_payload) && *p != '\r' && *p != '\n'; p++)
|
|
*p = (((size_t)p) & 1) ? tolower(*p) : toupper(*p);
|
|
res=VERDICT_MODIFY;
|
|
}
|
|
uint8_t *pua;
|
|
if (params.hostnospace &&
|
|
(pua = (uint8_t*)memmem(data_payload, len_payload, "\r\nUser-Agent: ", 14)) &&
|
|
(pua = (uint8_t*)memmem(pua + 1, len_payload - (pua - data_payload) - 1, "\r\n", 2)))
|
|
{
|
|
DLOG("removing space after Host: and adding it to User-Agent:\n")
|
|
if (pua > phost)
|
|
{
|
|
memmove(phost + 7, phost + 8, pua - phost - 8);
|
|
phost[pua - phost - 1] = ' ';
|
|
}
|
|
else
|
|
{
|
|
memmove(pua + 1, pua, phost - pua + 7);
|
|
*pua = ' ';
|
|
}
|
|
res=VERDICT_MODIFY;
|
|
}
|
|
}
|
|
|
|
if (params.desync_mode==DESYNC_NONE) return res;
|
|
|
|
if (params.debug)
|
|
{
|
|
printf("dpi desync src=");
|
|
print_sockaddr((struct sockaddr *)&src);
|
|
printf(" dst=");
|
|
print_sockaddr((struct sockaddr *)&dst);
|
|
printf("\n");
|
|
}
|
|
|
|
enum dpi_desync_mode desync_mode = params.desync_mode;
|
|
uint32_t fooling_orig = FOOL_NONE;
|
|
bool b;
|
|
|
|
pkt1_len = sizeof(pkt1);
|
|
b = false;
|
|
switch(desync_mode)
|
|
{
|
|
case DESYNC_FAKE_KNOWN:
|
|
if (!bKnownProtocol)
|
|
{
|
|
DLOG("not applying fake because of unknown protocol\n");
|
|
desync_mode = params.desync_mode2;
|
|
break;
|
|
}
|
|
case DESYNC_FAKE:
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_fake,params.desync_fooling_mode,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
fake, fake_size, pkt1, &pkt1_len))
|
|
{
|
|
return res;
|
|
}
|
|
DLOG("sending fake request : ");
|
|
hexdump_limited_dlog(fake,fake_size,PKTDATA_MAXDUMP); DLOG("\n")
|
|
b = true;
|
|
break;
|
|
case DESYNC_RST:
|
|
case DESYNC_RSTACK:
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, TH_RST | (desync_mode==DESYNC_RSTACK ? TH_ACK:0), tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_fake,params.desync_fooling_mode,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
NULL, 0, pkt1, &pkt1_len))
|
|
{
|
|
return res;
|
|
}
|
|
DLOG("sending fake RST/RSTACK\n");
|
|
b = true;
|
|
break;
|
|
case DESYNC_HOPBYHOP:
|
|
case DESYNC_DESTOPT:
|
|
case DESYNC_IPFRAG1:
|
|
fooling_orig = (desync_mode==DESYNC_HOPBYHOP) ? FOOL_HOPBYHOP : (desync_mode==DESYNC_DESTOPT) ? FOOL_DESTOPT : FOOL_IPFRAG1;
|
|
if (ip6hdr && (params.desync_mode2==DESYNC_NONE || !desync_valid_second_stage_tcp(params.desync_mode2)))
|
|
{
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_orig,fooling_orig,0,0,
|
|
data_payload, len_payload, pkt1, &pkt1_len))
|
|
{
|
|
return res;
|
|
}
|
|
DLOG("resending original packet with extension header\n");
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
// this mode is final, no other options available
|
|
return VERDICT_DROP;
|
|
}
|
|
desync_mode = params.desync_mode2;
|
|
}
|
|
|
|
if (b)
|
|
{
|
|
if (!rawsend_rep((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
if (params.desync_mode2==DESYNC_NONE || !desync_valid_second_stage_tcp(params.desync_mode2))
|
|
{
|
|
if (params.desync_retrans)
|
|
{
|
|
DLOG("dropping original packet to force retransmission. len=%zu len_payload=%zu\n", *len_pkt, len_payload)
|
|
}
|
|
else
|
|
{
|
|
DLOG("reinjecting original packet. len=%zu len_payload=%zu\n", *len_pkt, len_payload)
|
|
#ifdef __FreeBSD__
|
|
// FreeBSD tend to pass ipv6 frames with wrong checksum
|
|
if ((res & VERDICT_MASK)==VERDICT_MODIFY || ip6hdr)
|
|
#else
|
|
// if original packet was tampered earlier it needs checksum fixed
|
|
if ((res & VERDICT_MASK)==VERDICT_MODIFY)
|
|
#endif
|
|
tcp_fix_checksum(tcphdr,len_tcp,ip,ip6hdr);
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , data_pkt, *len_pkt))
|
|
return res;
|
|
}
|
|
return VERDICT_DROP;
|
|
}
|
|
desync_mode = params.desync_mode2;
|
|
}
|
|
|
|
size_t split_pos=len_payload>params.desync_split_pos ? params.desync_split_pos : 1;
|
|
pkt1_len = sizeof(pkt1);
|
|
switch(desync_mode)
|
|
{
|
|
case DESYNC_DISORDER:
|
|
case DESYNC_DISORDER2:
|
|
{
|
|
uint8_t fakeseg[DPI_DESYNC_MAX_FAKE_LEN+100];
|
|
size_t fakeseg_len;
|
|
|
|
if (split_pos<len_payload)
|
|
{
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, net32_add(tcphdr->th_seq,split_pos), tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_orig,fooling_orig,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
data_payload+split_pos, len_payload-split_pos, pkt1, &pkt1_len))
|
|
return res;
|
|
DLOG("sending 2nd out-of-order tcp segment %zu-%zu len=%zu : ",split_pos,len_payload-1, len_payload-split_pos)
|
|
hexdump_limited_dlog(data_payload+split_pos,len_payload-split_pos,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
}
|
|
|
|
|
|
if (desync_mode==DESYNC_DISORDER)
|
|
{
|
|
fakeseg_len = sizeof(fakeseg);
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_fake,params.desync_fooling_mode,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
zeropkt, split_pos, fakeseg, &fakeseg_len))
|
|
return res;
|
|
DLOG("sending fake(1) 1st out-of-order tcp segment 0-%zu len=%zu : ",split_pos-1, split_pos)
|
|
hexdump_limited_dlog(zeropkt,split_pos,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend_rep((struct sockaddr *)&dst, desync_fwmark, ifout , fakeseg, fakeseg_len))
|
|
return res;
|
|
}
|
|
|
|
|
|
pkt1_len = sizeof(pkt1);
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_orig,fooling_orig,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
data_payload, split_pos, pkt1, &pkt1_len))
|
|
return res;
|
|
DLOG("sending 1st out-of-order tcp segment 0-%zu len=%zu : ",split_pos-1, split_pos)
|
|
hexdump_limited_dlog(data_payload,split_pos,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
|
|
if (desync_mode==DESYNC_DISORDER)
|
|
{
|
|
DLOG("sending fake(2) 1st out-of-order tcp segment 0-%zu len=%zu : ",split_pos-1, split_pos)
|
|
hexdump_limited_dlog(zeropkt,split_pos,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend_rep((struct sockaddr *)&dst, desync_fwmark, ifout , fakeseg, fakeseg_len))
|
|
return res;
|
|
}
|
|
|
|
return VERDICT_DROP;
|
|
}
|
|
break;
|
|
case DESYNC_SPLIT:
|
|
case DESYNC_SPLIT2:
|
|
{
|
|
uint8_t fakeseg[DPI_DESYNC_MAX_FAKE_LEN+100];
|
|
size_t fakeseg_len;
|
|
|
|
if (desync_mode==DESYNC_SPLIT)
|
|
{
|
|
fakeseg_len = sizeof(fakeseg);
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_fake,params.desync_fooling_mode,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
zeropkt, split_pos, fakeseg, &fakeseg_len))
|
|
return res;
|
|
DLOG("sending fake(1) 1st tcp segment 0-%zu len=%zu : ",split_pos-1, split_pos)
|
|
hexdump_limited_dlog(zeropkt,split_pos,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend_rep((struct sockaddr *)&dst, desync_fwmark, ifout , fakeseg, fakeseg_len))
|
|
return res;
|
|
}
|
|
|
|
pkt1_len = sizeof(pkt1);
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, tcphdr->th_seq, tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_orig,fooling_orig,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
data_payload, split_pos, pkt1, &pkt1_len))
|
|
return res;
|
|
DLOG("sending 1st tcp segment 0-%zu len=%zu : ",split_pos-1, split_pos)
|
|
hexdump_limited_dlog(data_payload,split_pos,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
|
|
if (desync_mode==DESYNC_SPLIT)
|
|
{
|
|
DLOG("sending fake(2) 1st tcp segment 0-%zu len=%zu : ",split_pos-1, split_pos)
|
|
hexdump_limited_dlog(zeropkt,split_pos,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend_rep((struct sockaddr *)&dst, desync_fwmark, ifout , fakeseg, fakeseg_len))
|
|
return res;
|
|
}
|
|
|
|
if (split_pos<len_payload)
|
|
{
|
|
pkt1_len = sizeof(pkt1);
|
|
if (!prepare_tcp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, flags_orig, net32_add(tcphdr->th_seq,split_pos), tcphdr->th_ack, tcphdr->th_win, scale_factor, timestamps,
|
|
ttl_orig,fooling_orig,params.desync_badseq_increment,params.desync_badseq_ack_increment,
|
|
data_payload+split_pos, len_payload-split_pos, pkt1, &pkt1_len))
|
|
return res;
|
|
DLOG("sending 2nd tcp segment %zu-%zu len=%zu : ",split_pos,len_payload-1, len_payload-split_pos)
|
|
hexdump_limited_dlog(data_payload+split_pos,len_payload-split_pos,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
}
|
|
|
|
return VERDICT_DROP;
|
|
}
|
|
break;
|
|
case DESYNC_IPFRAG2:
|
|
{
|
|
#ifdef __FreeBSD__
|
|
// FreeBSD tend to pass ipv6 frames with wrong checksum
|
|
if ((res & VERDICT_MASK)==VERDICT_MODIFY || ip6hdr)
|
|
#else
|
|
// if original packet was tampered earlier it needs checksum fixed
|
|
if ((res & VERDICT_MASK)==VERDICT_MODIFY)
|
|
#endif
|
|
tcp_fix_checksum(tcphdr,len_tcp,ip,ip6hdr);
|
|
|
|
uint8_t pkt3[DPI_DESYNC_MAX_FAKE_LEN+100], *pkt_orig;
|
|
size_t pkt_orig_len;
|
|
|
|
size_t ipfrag_pos = (params.desync_ipfrag_pos_tcp && params.desync_ipfrag_pos_tcp<len_tcp) ? params.desync_ipfrag_pos_tcp : 24;
|
|
uint32_t ident = ip ? ip->ip_id ? ip->ip_id : htons(1+random()%0xFFFF) : htonl(1+random()%0xFFFFFFFF);
|
|
|
|
pkt1_len = sizeof(pkt1);
|
|
pkt2_len = sizeof(pkt2);
|
|
|
|
if (ip6hdr && (fooling_orig==FOOL_HOPBYHOP || fooling_orig==FOOL_DESTOPT))
|
|
{
|
|
pkt_orig_len = sizeof(pkt3);
|
|
if (!ip6_insert_simple_hdr(fooling_orig==FOOL_HOPBYHOP ? IPPROTO_HOPOPTS : IPPROTO_DSTOPTS, data_pkt, *len_pkt, pkt3, &pkt_orig_len))
|
|
return res;
|
|
pkt_orig = pkt3;
|
|
}
|
|
else
|
|
{
|
|
pkt_orig = data_pkt;
|
|
pkt_orig_len = *len_pkt;
|
|
}
|
|
|
|
if (!ip_frag(pkt_orig, pkt_orig_len, ipfrag_pos, ident, pkt1, &pkt1_len, pkt2, &pkt2_len))
|
|
return res;
|
|
|
|
DLOG("sending 1st ip fragment 0-%zu len=%zu : ", ipfrag_pos-1, ipfrag_pos)
|
|
hexdump_limited_dlog(pkt1,pkt1_len,IP_MAXDUMP); DLOG("\n")
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt2, pkt2_len))
|
|
return res;
|
|
|
|
DLOG("sending 2nd ip fragment %zu-%zu len=%zu : ", ipfrag_pos, len_tcp-1, len_tcp-ipfrag_pos)
|
|
hexdump_limited_dlog(pkt2,pkt2_len,IP_MAXDUMP); DLOG("\n")
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
|
|
return VERDICT_DROP;
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
return res;
|
|
}
|
|
|
|
|
|
|
|
uint8_t dpi_desync_udp_packet(uint32_t fwmark, const char *ifout, uint8_t *data_pkt, size_t *len_pkt, struct ip *ip, struct ip6_hdr *ip6hdr, struct udphdr *udphdr, uint8_t *data_payload, size_t len_payload)
|
|
{
|
|
uint8_t res=VERDICT_PASS;
|
|
t_ctrack *ctrack=NULL;
|
|
bool bReverse=false;
|
|
|
|
struct sockaddr_storage src, dst;
|
|
uint8_t pkt1[DPI_DESYNC_MAX_FAKE_LEN+100], pkt2[DPI_DESYNC_MAX_FAKE_LEN+100];
|
|
size_t pkt1_len, pkt2_len;
|
|
uint8_t ttl_orig,ttl_fake;
|
|
|
|
if (!!ip == !!ip6hdr) return res; // one and only one must be present
|
|
|
|
ConntrackPoolPurge(¶ms.conntrack);
|
|
if (ConntrackPoolFeed(¶ms.conntrack, ip, ip6hdr, NULL, udphdr, len_payload, &ctrack, &bReverse))
|
|
maybe_cutoff(ctrack, IPPROTO_UDP);
|
|
HostFailPoolPurgeRateLimited(¶ms.hostlist_auto_fail_counters);
|
|
|
|
//ConntrackPoolDump(¶ms.conntrack);
|
|
|
|
if (bReverse) return res; // nothing to do. do not waste cpu
|
|
|
|
if (params.desync_cutoff)
|
|
{
|
|
if (ctrack)
|
|
{
|
|
if (ctrack->b_desync_cutoff)
|
|
{
|
|
DLOG("not desyncing. desync-cutoff reached (mode %c): %llu/%u\n", params.desync_cutoff_mode, (unsigned long long)cutoff_get_limit(ctrack,params.desync_cutoff_mode), params.desync_cutoff);
|
|
return res;
|
|
}
|
|
DLOG("desync-cutoff not reached (mode %c): %llu/%u\n", params.desync_cutoff_mode, (unsigned long long)cutoff_get_limit(ctrack,params.desync_cutoff_mode), params.desync_cutoff);
|
|
}
|
|
else
|
|
{
|
|
DLOG("not desyncing. desync-cutoff is set but conntrack entry is missing\n");
|
|
return res;
|
|
}
|
|
}
|
|
|
|
if (params.desync_mode==DESYNC_NONE && !*params.hostlist_auto_filename) return res; // do not waste cpu
|
|
|
|
if (len_payload)
|
|
{
|
|
const uint8_t *fake;
|
|
size_t fake_size;
|
|
bool b;
|
|
char host[256];
|
|
bool bHaveHost=false;
|
|
bool bKnownProtocol=false;
|
|
|
|
if (IsQUICInitial(data_payload,len_payload))
|
|
{
|
|
DLOG("packet contains QUIC initial\n")
|
|
|
|
if (ctrack && !ctrack->l7proto) ctrack->l7proto = QUIC;
|
|
fake = params.fake_quic;
|
|
fake_size = params.fake_quic_size;
|
|
|
|
bool bIsCryptoHello, bDecryptOK;
|
|
bHaveHost=QUICExtractHostFromInitial(data_payload,len_payload,host,sizeof(host), &bDecryptOK,&bIsCryptoHello);
|
|
if (bIsCryptoHello)
|
|
{
|
|
// decrypted and payload is ClientHello
|
|
if (params.desync_skip_nosni && !bHaveHost)
|
|
{
|
|
DLOG("not applying tampering to QUIC ClientHello without hostname in the SNI\n")
|
|
return res;
|
|
}
|
|
}
|
|
else if (!bDecryptOK)
|
|
{
|
|
// could not decrypt
|
|
if (params.desync_skip_nosni)
|
|
{
|
|
DLOG("not applying tampering to QUIC initial that could not be decrypted\n")
|
|
return res;
|
|
}
|
|
else
|
|
// consider this case the same way as absence of the SNI. DPI also might not be able to decrypt this and get SNI
|
|
DLOG("QUIC initial decryption failed. still applying tampering because desync_skip_nosni is not set\n")
|
|
}
|
|
else
|
|
{
|
|
// decrypted and payload is not ClientHello
|
|
if (params.desync_any_proto)
|
|
{
|
|
DLOG("QUIC initial without CRYPTO frame. applying tampering because desync_any_proto is set\n")
|
|
}
|
|
else
|
|
{
|
|
DLOG("not applying tampering to QUIC initial without CRYPTO frame\n")
|
|
return res;
|
|
}
|
|
}
|
|
bKnownProtocol = true;
|
|
}
|
|
else
|
|
{
|
|
// received payload without host. it means we are out of the request retransmission phase. stop counter
|
|
ctrack_stop_retrans_counter(ctrack);
|
|
|
|
if (IsWireguardHandshakeInitiation(data_payload,len_payload))
|
|
{
|
|
DLOG("packet contains wireguard handshake initiation\n")
|
|
if (ctrack && !ctrack->l7proto) ctrack->l7proto = WIREGUARD;
|
|
fake = params.fake_wg;
|
|
fake_size = params.fake_wg_size;
|
|
bKnownProtocol = true;
|
|
}
|
|
else if (IsDhtD1(data_payload,len_payload))
|
|
{
|
|
DLOG("packet contains DHT d1...e\n")
|
|
if (ctrack && !ctrack->l7proto) ctrack->l7proto = DHT;
|
|
fake = params.fake_dht;
|
|
fake_size = params.fake_dht_size;
|
|
bKnownProtocol = true;
|
|
}
|
|
else
|
|
{
|
|
if (!params.desync_any_proto) return res;
|
|
DLOG("applying tampering to unknown protocol\n")
|
|
fake = params.fake_unknown_udp;
|
|
fake_size = params.fake_unknown_udp_size;
|
|
}
|
|
}
|
|
|
|
if (bHaveHost)
|
|
{
|
|
DLOG("hostname: %s\n",host)
|
|
bool bExcluded;
|
|
if ((params.hostlist || params.hostlist_exclude) && !HostlistCheck(host, &bExcluded))
|
|
{
|
|
DLOG("not applying tampering to this request\n")
|
|
if (!bExcluded && *params.hostlist_auto_filename && ctrack)
|
|
{
|
|
if (!ctrack->hostname) ctrack->hostname=strdup(host);
|
|
process_retrans_fail(ctrack, IPPROTO_UDP);
|
|
}
|
|
return res;
|
|
}
|
|
}
|
|
|
|
enum dpi_desync_mode desync_mode = params.desync_mode;
|
|
uint32_t fooling_orig = FOOL_NONE;
|
|
|
|
ttl_orig = ip ? ip->ip_ttl : ip6hdr->ip6_ctlun.ip6_un1.ip6_un1_hlim;
|
|
if (ip6hdr) ttl_fake = params.desync_ttl6 ? params.desync_ttl6 : ttl_orig;
|
|
else ttl_fake = params.desync_ttl ? params.desync_ttl : ttl_orig;
|
|
extract_endpoints(ip, ip6hdr, NULL, udphdr, &src, &dst);
|
|
|
|
if (params.debug)
|
|
{
|
|
printf("dpi desync src=");
|
|
print_sockaddr((struct sockaddr *)&src);
|
|
printf(" dst=");
|
|
print_sockaddr((struct sockaddr *)&dst);
|
|
printf("\n");
|
|
}
|
|
|
|
uint32_t desync_fwmark = fwmark | params.desync_fwmark;
|
|
|
|
pkt1_len = sizeof(pkt1);
|
|
b = false;
|
|
switch(desync_mode)
|
|
{
|
|
case DESYNC_FAKE_KNOWN:
|
|
if (!bKnownProtocol)
|
|
{
|
|
DLOG("not applying fake because of unknown protocol\n");
|
|
desync_mode = params.desync_mode2;
|
|
break;
|
|
}
|
|
case DESYNC_FAKE:
|
|
if (!prepare_udp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, ttl_fake, params.desync_fooling_mode, NULL, 0, 0, fake, fake_size, pkt1, &pkt1_len))
|
|
return res;
|
|
DLOG("sending fake request : ");
|
|
hexdump_limited_dlog(fake,fake_size,PKTDATA_MAXDUMP); DLOG("\n")
|
|
if (!rawsend_rep((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
b = true;
|
|
break;
|
|
case DESYNC_HOPBYHOP:
|
|
case DESYNC_DESTOPT:
|
|
case DESYNC_IPFRAG1:
|
|
fooling_orig = (desync_mode==DESYNC_HOPBYHOP) ? FOOL_HOPBYHOP : (desync_mode==DESYNC_DESTOPT) ? FOOL_DESTOPT : FOOL_IPFRAG1;
|
|
if (ip6hdr && (params.desync_mode2==DESYNC_NONE || !desync_valid_second_stage_udp(params.desync_mode2)))
|
|
{
|
|
if (!prepare_udp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst,
|
|
ttl_orig,fooling_orig,NULL,0,0,
|
|
data_payload, len_payload, pkt1, &pkt1_len))
|
|
{
|
|
return res;
|
|
}
|
|
DLOG("resending original packet with extension header\n");
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
// this mode is final, no other options available
|
|
return ct_new_postnat_fix_udp(ctrack, ip, ip6hdr, udphdr, len_pkt);
|
|
}
|
|
desync_mode = params.desync_mode2;
|
|
break;
|
|
}
|
|
|
|
if (b)
|
|
{
|
|
if (params.desync_mode2==DESYNC_NONE || !desync_valid_second_stage_udp(params.desync_mode2))
|
|
{
|
|
DLOG("reinjecting original packet. len=%zu len_payload=%zu\n", *len_pkt, len_payload)
|
|
#ifdef __FreeBSD__
|
|
// FreeBSD tend to pass ipv6 frames with wrong checksum
|
|
if ((res & VERDICT_MASK)==VERDICT_MODIFY || ip6hdr)
|
|
#else
|
|
// if original packet was tampered earlier it needs checksum fixed
|
|
if ((res & VERDICT_MASK)==VERDICT_MODIFY)
|
|
#endif
|
|
udp_fix_checksum(udphdr,sizeof(struct udphdr)+len_payload,ip,ip6hdr);
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , data_pkt, *len_pkt))
|
|
return res;
|
|
return ct_new_postnat_fix_udp(ctrack, ip, ip6hdr, udphdr, len_pkt);
|
|
}
|
|
desync_mode = params.desync_mode2;
|
|
}
|
|
|
|
switch(desync_mode)
|
|
{
|
|
case DESYNC_UDPLEN:
|
|
pkt1_len = sizeof(pkt1);
|
|
if (!prepare_udp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, ttl_orig,fooling_orig, params.udplen_pattern, sizeof(params.udplen_pattern), params.udplen_increment, data_payload, len_payload, pkt1, &pkt1_len))
|
|
{
|
|
DLOG("could not construct packet with modified length. too large ?\n");
|
|
return res;
|
|
}
|
|
DLOG("resending original packet with increased by %d length\n", params.udplen_increment);
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
return ct_new_postnat_fix_udp(ctrack, ip, ip6hdr, udphdr, len_pkt);
|
|
case DESYNC_TAMPER:
|
|
if (IsDhtD1(data_payload,len_payload))
|
|
{
|
|
size_t szbuf,szcopy;
|
|
memcpy(pkt2,"d2:001:x",8);
|
|
pkt2_len=8;
|
|
szbuf=sizeof(pkt2)-pkt2_len;
|
|
szcopy=len_payload-1;
|
|
if (szcopy>szbuf)
|
|
{
|
|
DLOG("packet is too long to tamper");
|
|
return res;
|
|
}
|
|
memcpy(pkt2+pkt2_len,data_payload+1,szcopy);
|
|
pkt2_len+=szcopy;
|
|
pkt1_len = sizeof(pkt1);
|
|
if (!prepare_udp_segment((struct sockaddr *)&src, (struct sockaddr *)&dst, ttl_orig,fooling_orig, NULL, 0 , 0, pkt2, pkt2_len, pkt1, &pkt1_len))
|
|
{
|
|
DLOG("could not construct packet with modified length. too large ?\n");
|
|
return res;
|
|
}
|
|
DLOG("resending tampered DHT\n");
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
return ct_new_postnat_fix_udp(ctrack, ip, ip6hdr, udphdr, len_pkt);
|
|
}
|
|
else
|
|
{
|
|
DLOG("payload is not tamperable\n");
|
|
return res;
|
|
}
|
|
case DESYNC_IPFRAG2:
|
|
{
|
|
|
|
#ifdef __FreeBSD__
|
|
// FreeBSD tend to pass ipv6 frames with wrong checksum
|
|
if ((res & VERDICT_MASK)==VERDICT_MODIFY || ip6hdr)
|
|
#else
|
|
// if original packet was tampered earlier it needs checksum fixed
|
|
if ((res & VERDICT_MASK)==VERDICT_MODIFY)
|
|
#endif
|
|
udp_fix_checksum(udphdr,sizeof(struct udphdr)+len_payload,ip,ip6hdr);
|
|
|
|
uint8_t pkt3[DPI_DESYNC_MAX_FAKE_LEN+100], *pkt_orig;
|
|
size_t pkt_orig_len;
|
|
|
|
size_t len_transport = len_payload + sizeof(struct udphdr);
|
|
size_t ipfrag_pos = (params.desync_ipfrag_pos_udp && params.desync_ipfrag_pos_udp<len_transport) ? params.desync_ipfrag_pos_udp : sizeof(struct udphdr);
|
|
// freebsd do not set ip.id
|
|
uint32_t ident = ip ? ip->ip_id ? ip->ip_id : htons(1+random()%0xFFFF) : htonl(1+random()%0xFFFFFFFF);
|
|
|
|
pkt1_len = sizeof(pkt1);
|
|
pkt2_len = sizeof(pkt2);
|
|
|
|
if (ip6hdr && (fooling_orig==FOOL_HOPBYHOP || fooling_orig==FOOL_DESTOPT))
|
|
{
|
|
pkt_orig_len = sizeof(pkt3);
|
|
if (!ip6_insert_simple_hdr(fooling_orig==FOOL_HOPBYHOP ? IPPROTO_HOPOPTS : IPPROTO_DSTOPTS, data_pkt, *len_pkt, pkt3, &pkt_orig_len))
|
|
return res;
|
|
pkt_orig = pkt3;
|
|
}
|
|
else
|
|
{
|
|
pkt_orig = data_pkt;
|
|
pkt_orig_len = *len_pkt;
|
|
}
|
|
|
|
if (!ip_frag(pkt_orig, pkt_orig_len, ipfrag_pos, ident, pkt1, &pkt1_len, pkt2, &pkt2_len))
|
|
return res;
|
|
|
|
DLOG("sending 1st ip fragment 0-%zu len=%zu : ", ipfrag_pos-1, ipfrag_pos)
|
|
hexdump_limited_dlog(pkt1,pkt1_len,IP_MAXDUMP); DLOG("\n")
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt2, pkt2_len))
|
|
return res;
|
|
|
|
DLOG("sending 2nd ip fragment %zu-%zu len=%zu : ", ipfrag_pos, len_transport-1, len_transport-ipfrag_pos)
|
|
hexdump_limited_dlog(pkt2,pkt2_len,IP_MAXDUMP); DLOG("\n")
|
|
if (!rawsend((struct sockaddr *)&dst, desync_fwmark, ifout , pkt1, pkt1_len))
|
|
return res;
|
|
|
|
return ct_new_postnat_fix_udp(ctrack, ip, ip6hdr, udphdr, len_pkt);
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
return res;
|
|
}
|