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GoodbyeDPI/goodbyedpi.c

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/*
* GoodbyeDPI — Passive DPI blocker and Active DPI circumvention utility.
*/
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include <getopt.h>
#include "windivert.h"
#include "goodbyedpi.h"
#include "dnsredir.h"
#include "blackwhitelist.h"
#define die() do { printf("Something went wrong!\n" \
"Make sure you're running this program with administrator privileges\n"); \
sleep(10); exit(EXIT_FAILURE); } while (0)
#define MAX_FILTERS 4
#define MAX_PACKET_SIZE 9016
#define DIVERT_NO_LOCALNETS_DST "(" \
"(ip.DstAddr < 127.0.0.1 or ip.DstAddr > 127.255.255.255) and " \
"(ip.DstAddr < 10.0.0.0 or ip.DstAddr > 10.255.255.255) and " \
"(ip.DstAddr < 192.168.0.0 or ip.DstAddr > 192.168.255.255) and " \
"(ip.DstAddr < 172.16.0.0 or ip.DstAddr > 172.31.255.255) and " \
"(ip.DstAddr < 169.254.0.0 or ip.DstAddr > 169.254.255.255)" \
")"
#define DIVERT_NO_LOCALNETS_SRC "(" \
"(ip.SrcAddr < 127.0.0.1 or ip.SrcAddr > 127.255.255.255) and " \
"(ip.SrcAddr < 10.0.0.0 or ip.SrcAddr > 10.255.255.255) and " \
"(ip.SrcAddr < 192.168.0.0 or ip.SrcAddr > 192.168.255.255) and " \
"(ip.SrcAddr < 172.16.0.0 or ip.SrcAddr > 172.31.255.255) and " \
"(ip.SrcAddr < 169.254.0.0 or ip.SrcAddr > 169.254.255.255)" \
")"
#define SET_HTTP_FRAGMENT_SIZE_OPTION(fragment_size) do { \
if (!http_fragment_size) { \
if (fragment_size <= 0 || fragment_size > 65535) { \
printf(fragment_size_message); \
exit(EXIT_FAILURE); \
} \
http_fragment_size = fragment_size; \
} \
else if (http_fragment_size != (unsigned int)fragment_size) { \
printf( \
"WARNING: HTTP fragment size is already set to %d, not changing.\n", \
http_fragment_size \
); \
} \
} while (0)
static HANDLE filters[MAX_FILTERS];
static int filter_num = 0;
static const char *http10_redirect_302 = "HTTP/1.0 302 ";
static const char *http11_redirect_302 = "HTTP/1.1 302 ";
static const char *http_host_find = "\r\nHost: ";
static const char *http_host_replace = "\r\nhoSt: ";
static const char *http_useragent_find = "\r\nUser-Agent: ";
static const char *location_http = "\r\nLocation: http://";
static const char *connection_close = "\r\nConnection: close";
static const char *http_methods[] = {
"GET ",
"HEAD ",
"POST ",
"PUT ",
"DELETE ",
"CONNECT ",
"OPTIONS ",
};
static struct option long_options[] = {
{"port", required_argument, 0, 'z' },
{"dns-addr", required_argument, 0, 'd' },
{"dns-port", required_argument, 0, 'g' },
{"dns-verb", no_argument, 0, 'v' },
{"blacklist", required_argument, 0, 'b' },
{0, 0, 0, 0 }
};
static char *filter_string = NULL;
static char *filter_string_template = "(ip and tcp and "
"(inbound and (("
"((ip.Id == 0x0001 or ip.Id == 0x0000) and tcp.SrcPort == 80 and tcp.Ack) or "
"((tcp.SrcPort == 80 or tcp.SrcPort == 443) and tcp.Ack and tcp.Syn)"
") and " DIVERT_NO_LOCALNETS_SRC ") or "
"(outbound and "
"(tcp.DstPort == 80 or tcp.DstPort == 443) and tcp.Ack and "
DIVERT_NO_LOCALNETS_DST ")"
"))";
static void add_filter_str(int proto, int port) {
const char *udp = " or (ip and udp and (udp.SrcPort == %d or udp.DstPort == %d))";
const char *tcp = " or (ip and tcp and (tcp.SrcPort == %d or tcp.DstPort == %d))";
char *current_filter = filter_string;
int new_filter_size = strlen(current_filter) +
(proto == IPPROTO_UDP ? strlen(udp) : strlen(tcp)) + 16;
char *new_filter = malloc(new_filter_size);
strcpy(new_filter, current_filter);
if (proto == IPPROTO_UDP)
sprintf(&(new_filter[strlen(new_filter)]), udp, port, port);
else
sprintf(&(new_filter[strlen(new_filter)]), tcp, port, port);
filter_string = new_filter;
free(current_filter);
}
static char* dumb_memmem(const char* haystack, int hlen, const char* needle, int nlen) {
// naive implementation
if (nlen > hlen) return NULL;
int i;
for (i=0; i<hlen-nlen+1; i++) {
if (memcmp(haystack+i,needle,nlen)==0) {
return (char*)(haystack+i);
}
}
return NULL;
}
static HANDLE init(char *filter, UINT64 flags) {
LPTSTR errormessage = NULL;
filter = WinDivertOpen(filter, WINDIVERT_LAYER_NETWORK, 0, flags);
if (filter != INVALID_HANDLE_VALUE)
return filter;
FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
NULL, GetLastError(), MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
(LPTSTR)&errormessage, 0, NULL);
printf("%s", errormessage);
free(errormessage);
return NULL;
}
static int deinit(HANDLE handle) {
if (handle) {
WinDivertClose(handle);
return TRUE;
}
return FALSE;
}
static void deinit_all() {
for (int i = 0; i < filter_num; i++) {
deinit(filters[i]);
}
}
static void sigint_handler(int sig __attribute__((unused))) {
deinit_all();
exit(EXIT_SUCCESS);
}
static void mix_case(char *pktdata, int pktlen) {
int i;
if (pktlen <= 0) return;
for (i = 0; i < pktlen; i++) {
if (i % 2) {
pktdata[i] = toupper(pktdata[i]);
}
}
}
static int is_passivedpi_redirect(const char *pktdata, int pktlen) {
/* First check if this is HTTP 302 redirect */
if (memcmp(pktdata, http11_redirect_302, strlen(http11_redirect_302)) == 0 ||
memcmp(pktdata, http10_redirect_302, strlen(http10_redirect_302)) == 0)
{
/* Then check if this is a redirect to new http site with Connection: close */
if (dumb_memmem(pktdata, pktlen, location_http, strlen(location_http)) &&
dumb_memmem(pktdata, pktlen, connection_close, strlen(connection_close))) {
return TRUE;
}
}
return FALSE;
}
static int find_header_and_get_info(const char *pktdata, int pktlen,
const char *hdrname,
char **hdrnameaddr,
char **hdrvalueaddr, int *hdrvaluelen) {
char *data_addr_rn;
char *hdr_begin;
*hdrvaluelen = 0;
*hdrnameaddr = NULL;
*hdrvalueaddr = NULL;
/* Search for the header */
hdr_begin = dumb_memmem(pktdata, pktlen,
hdrname, strlen(hdrname));
if (!hdr_begin) return FALSE;
if ((PVOID)pktdata > (PVOID)hdr_begin) return FALSE;
/* Set header address */
*hdrnameaddr = hdr_begin;
*hdrvalueaddr = (PVOID)hdr_begin + strlen(hdrname);
/* Search for header end (\r\n) */
data_addr_rn = dumb_memmem(*hdrvalueaddr,
pktlen - ((PVOID)*hdrvalueaddr - (PVOID)pktdata),
"\r\n", 2);
if (data_addr_rn) {
*hdrvaluelen = (PVOID)data_addr_rn - (PVOID)*hdrvalueaddr;
if (*hdrvaluelen > 0 && *hdrvaluelen <= 512)
return TRUE;
}
return FALSE;
}
static inline void change_window_size(const PWINDIVERT_TCPHDR ppTcpHdr, int size) {
if (size >= 1 && size <= 65535) {
ppTcpHdr->Window = htons(size);
}
}
/* HTTP method end without trailing space */
static PVOID find_http_method_end(const char *pkt, int http_frag, int *is_fragmented) {
unsigned int i;
for (i = 0; i<(sizeof(http_methods) / sizeof(*http_methods)); i++) {
if (memcmp(pkt, http_methods[i], strlen(http_methods[i])) == 0) {
if (is_fragmented)
*is_fragmented = 0;
return (char*)pkt + strlen(http_methods[i]) - 1;
}
/* Try to find HTTP method in a second part of fragmented packet */
if ((http_frag == 1 || http_frag == 2) &&
memcmp(pkt, http_methods[i] + http_frag,
strlen(http_methods[i]) - http_frag) == 0
)
{
if (is_fragmented)
*is_fragmented = 1;
return (char*)pkt + strlen(http_methods[i]) - http_frag - 1;
}
}
return NULL;
}
int main(int argc, char *argv[]) {
static const char fragment_size_message[] =
"Fragment size should be in range [0 - 65535]\n";
int i, should_reinject, should_recalc_checksum = 0;
int opt;
HANDLE w_filter = NULL;
WINDIVERT_ADDRESS addr;
char packet[MAX_PACKET_SIZE];
PVOID packet_data;
UINT packetLen;
UINT packet_dataLen;
PWINDIVERT_IPHDR ppIpHdr;
PWINDIVERT_TCPHDR ppTcpHdr;
PWINDIVERT_UDPHDR ppUdpHdr;
conntrack_info_t dns_conn_info;
int do_passivedpi = 0, do_fragment_http = 0,
do_fragment_http_persistent = 0,
do_fragment_http_persistent_nowait = 0,
do_fragment_https = 0, do_host = 0,
do_host_removespace = 0, do_additional_space = 0,
do_http_allports = 0,
do_host_mixedcase = 0, do_dns_redirect = 0,
do_dns_verb = 0, do_blacklist = 0;
unsigned int http_fragment_size = 2;
unsigned int https_fragment_size = 2;
uint32_t dns_addr = 0;
uint16_t dns_port = htons(53);
char *host_addr, *useragent_addr, *method_addr;
int host_len, useragent_len;
int http_req_fragmented;
char *hdr_name_addr = NULL, *hdr_value_addr = NULL;
int hdr_value_len;
if (filter_string == NULL) {
filter_string = malloc(strlen(filter_string_template) + 1);
strcpy(filter_string, filter_string_template);
}
printf("GoodbyeDPI: Passive DPI blocker and Active DPI circumvention utility\n");
if (argc == 1) {
/* enable mode -1 by default */
do_passivedpi = do_host = do_host_removespace \
= do_fragment_http = do_fragment_https = 1;
}
while ((opt = getopt_long(argc, argv, "1234prsaf:e:mwk:n", long_options, NULL)) != -1) {
switch (opt) {
case '1':
do_passivedpi = do_host = do_host_removespace \
= do_fragment_http = do_fragment_https \
= do_fragment_http_persistent \
= do_fragment_http_persistent_nowait = 1;
break;
case '2':
do_passivedpi = do_host = do_host_removespace \
= do_fragment_http = do_fragment_https \
= do_fragment_http_persistent \
= do_fragment_http_persistent_nowait = 1;
https_fragment_size = 40;
break;
case '3':
do_passivedpi = do_host = do_host_removespace \
= do_fragment_https = 1;
https_fragment_size = 40;
break;
case '4':
do_passivedpi = do_host = do_host_removespace = 1;
break;
case 'p':
do_passivedpi = 1;
break;
case 'r':
do_host = 1;
break;
case 's':
do_host_removespace = 1;
break;
case 'a':
do_additional_space = 1;
do_host_removespace = 1;
break;
case 'm':
do_host_mixedcase = 1;
break;
case 'f':
do_fragment_http = 1;
SET_HTTP_FRAGMENT_SIZE_OPTION(atoi(optarg));
break;
case 'k':
do_fragment_http_persistent = 1;
SET_HTTP_FRAGMENT_SIZE_OPTION(atoi(optarg));
break;
case 'n':
do_fragment_http_persistent_nowait = 1;
break;
case 'e':
do_fragment_https = 1;
https_fragment_size = atoi(optarg);
if (https_fragment_size <= 0 || https_fragment_size > 65535) {
printf(fragment_size_message);
exit(EXIT_FAILURE);
}
break;
case 'w':
do_http_allports = 1;
break;
case 'z':
/* i is used as a temporary variable here */
i = atoi(optarg);
if (i <= 0 || i > 65535) {
printf("Port parameter error!\n");
exit(EXIT_FAILURE);
}
if (i != 80 && i != 443)
add_filter_str(IPPROTO_TCP, i);
i = 0;
break;
case 'd':
if (!do_dns_redirect) {
do_dns_redirect = 1;
dns_addr = inet_addr(optarg);
if (!dns_addr) {
printf("DNS address parameter error!\n");
exit(EXIT_FAILURE);
}
add_filter_str(IPPROTO_UDP, 53);
flush_dns_cache();
}
break;
case 'g':
if (!do_dns_redirect) {
printf("--dns-port should be used with --dns-addr!\n"
"Make sure you use --dns-addr and pass it before "
"--dns-port\n");
exit(EXIT_FAILURE);
}
dns_port = atoi(optarg);
if (atoi(optarg) <= 0 || atoi(optarg) > 65535) {
printf("DNS port parameter error!\n");
exit(EXIT_FAILURE);
}
if (dns_port != 53) {
add_filter_str(IPPROTO_UDP, dns_port);
}
dns_port = ntohs(dns_port);
break;
case 'v':
do_dns_verb = 1;
break;
case 'b':
do_blacklist = 1;
if (!blackwhitelist_load_list(optarg)) {
printf("Can't load blacklist from file!\n");
exit(EXIT_FAILURE);
}
break;
default:
printf("Usage: goodbyedpi.exe [OPTION...]\n"
" -p block passive DPI\n"
" -r replace Host with hoSt\n"
" -s remove space between host header and its value\n"
" -a additional space between Method and Request-URI (enables -s, may break sites)\n"
" -m mix Host header case (test.com -> tEsT.cOm)\n"
" -f [value] set HTTP fragmentation to value\n"
" -k [value] enable HTTP persistent (keep-alive) fragmentation and set it to value\n"
" -n do not wait for first segment ACK when -k is enabled\n"
" -e [value] set HTTPS fragmentation to value\n"
" -w try to find and parse HTTP traffic on all processed ports (not only on port 80)\n"
" --port [value] additional TCP port to perform fragmentation on (and HTTP tricks with -w)\n"
" --dns-addr [value] redirect UDP DNS requests to the supplied IP address (experimental)\n"
" --dns-port [value] redirect UDP DNS requests to the supplied port (53 by default)\n"
" --dns-verb print verbose DNS redirection messages\n"
" --blacklist [txtfile] perform HTTP tricks only to host names and subdomains from\n"
" supplied text file. This option can be supplied multiple times.\n"
"\n"
" -1 -p -r -s -f 2 -k 2 -n -e 2 (most compatible mode, default)\n"
" -2 -p -r -s -f 2 -k 2 -n -e 40 (better speed for HTTPS yet still compatible)\n"
" -3 -p -r -s -e 40 (better speed for HTTP and HTTPS)\n"
" -4 -p -r -s (best speed)\n");
exit(EXIT_FAILURE);
}
}
printf("Block passive: %d, Fragment HTTP: %d, Fragment persistent HTTP: %d, "
"Fragment HTTPS: %d, "
"hoSt: %d, Host no space: %d, Additional space: %d, Mix Host: %d, "
"HTTP AllPorts: %d, HTTP Persistent Nowait: %d, DNS redirect: %d\n",
do_passivedpi, (do_fragment_http ? http_fragment_size : 0),
(do_fragment_http_persistent ? http_fragment_size : 0),
(do_fragment_https ? https_fragment_size : 0),
do_host, do_host_removespace, do_additional_space, do_host_mixedcase,
do_http_allports, do_fragment_http_persistent_nowait, do_dns_redirect
);
if (do_fragment_http && http_fragment_size > 2) {
printf("WARNING: HTTP fragmentation values > 2 are not fully compatible "
"with other options. Please use values <= 2 or disable HTTP fragmentation "
"completely.\n");
}
printf("\nOpening filter\n");
filter_num = 0;
if (do_passivedpi) {
/* IPv4 filter for inbound RST packets with ID = 0 or 1 */
filters[filter_num] = init(
"inbound and ip and tcp and "
"(ip.Id == 0x0001 or ip.Id == 0x0000) and "
"(tcp.SrcPort == 443 or tcp.SrcPort == 80) and tcp.Rst and "
DIVERT_NO_LOCALNETS_SRC,
WINDIVERT_FLAG_DROP);
filter_num++;
}
/*
* IPv4 filter for inbound HTTP redirection packets and
* active DPI circumvention
*/
filters[filter_num] = init(filter_string, 0);
w_filter = filters[filter_num];
filter_num++;
for (i = 0; i < filter_num; i++) {
if (filters[i] == NULL)
die();
}
printf("Filter activated!\n");
signal(SIGINT, sigint_handler);
while (1) {
if (WinDivertRecv(w_filter, packet, sizeof(packet), &addr, &packetLen)) {
//printf("Got %s packet, len=%d!\n", addr.Direction ? "inbound" : "outbound",
// packetLen);
should_reinject = 1;
should_recalc_checksum = 0;
if (WinDivertHelperParsePacket(packet, packetLen, &ppIpHdr,
NULL, NULL, NULL, &ppTcpHdr, NULL, &packet_data, &packet_dataLen)) {
//printf("Got parsed packet, len=%d!\n", packet_dataLen);
/* Got a TCP packet WITH DATA */
/* Handle INBOUND packet with data and find HTTP REDIRECT in there */
if (addr.Direction == WINDIVERT_DIRECTION_INBOUND && packet_dataLen > 16) {
/* If INBOUND packet with DATA (tcp.Ack) */
/* Drop packets from filter with HTTP 30x Redirect */
if (do_passivedpi && is_passivedpi_redirect(packet_data, packet_dataLen)) {
//printf("Dropping HTTP Redirect packet!\n");
should_reinject = 0;
}
}
/* Handle OUTBOUND packet on port 80, search for Host header */
else if (addr.Direction == WINDIVERT_DIRECTION_OUTBOUND &&
packet_dataLen > 16 &&
(do_http_allports ? 1 : (ppTcpHdr->DstPort == htons(80))) &&
find_http_method_end(packet_data,
(do_fragment_http ? http_fragment_size : 0),
&http_req_fragmented) &&
(do_host || do_host_removespace ||
do_host_mixedcase || do_fragment_http_persistent))
{
/* Find Host header */
if (find_header_and_get_info(packet_data, packet_dataLen,
http_host_find, &hdr_name_addr, &hdr_value_addr, &hdr_value_len) &&
hdr_value_len > 0 && hdr_value_len <= HOST_MAXLEN &&
(do_blacklist ? blackwhitelist_check_hostname(hdr_value_addr, hdr_value_len) : 1))
{
host_addr = hdr_value_addr;
host_len = hdr_value_len;
/*
* Handle new HTTP request in new
* connection (when Window Size modification disabled)
* or already established connection (keep-alive).
* We split HTTP request into two packets: one of http_fragment_size length
* and another of original_size - http_fragment_size length.
*
* The second packet of a splitted part is not really needed to be sent
* as Windows understand that is hasn't been sent by checking
* ack number of received packet and retransmitting missing part again,
* but it's better to send it anyway since it eliminates one RTT.
*/
if (do_fragment_http_persistent && !http_req_fragmented &&
(packet_dataLen > http_fragment_size)
) {
ppIpHdr->Length = htons(
ntohs(ppIpHdr->Length) -
packet_dataLen + http_fragment_size
);
WinDivertHelperCalcChecksums(
packet, packetLen - packet_dataLen + http_fragment_size, 0
);
WinDivertSend(
w_filter, packet,
packetLen - packet_dataLen + http_fragment_size,
&addr, NULL
);
if (do_fragment_http_persistent_nowait) {
ppIpHdr->Length = htons(
ntohs(ppIpHdr->Length) -
http_fragment_size + packet_dataLen - http_fragment_size
);
memmove(packet_data,
packet_data + http_fragment_size,
packet_dataLen);
packet_dataLen -= http_fragment_size;
packetLen -= http_fragment_size;
hdr_value_addr -= http_fragment_size;
hdr_name_addr -= http_fragment_size;
host_addr = hdr_value_addr;
ppTcpHdr->SeqNum = htonl(ntohl(ppTcpHdr->SeqNum) + http_fragment_size);
should_recalc_checksum = 1;
}
else {
continue;
}
}
if (do_host_mixedcase) {
mix_case(host_addr, host_len);
should_recalc_checksum = 1;
}
if (do_host) {
/* Replace "Host: " with "hoSt: " */
memcpy(hdr_name_addr, http_host_replace, strlen(http_host_replace));
should_recalc_checksum = 1;
//printf("Replaced Host header!\n");
}
/* If removing space between host header and its value
* and adding additional space between Method and Request-URI */
if (do_additional_space && do_host_removespace) {
/* End of "Host:" without trailing space */
method_addr = find_http_method_end(packet_data,
(do_fragment_http ? http_fragment_size : 0),
NULL);
if (method_addr) {
memmove(method_addr + 1, method_addr,
(PVOID)host_addr - (PVOID)method_addr - 1);
should_recalc_checksum = 1;
}
}
/* If just removing space between host header and its value */
else if (do_host_removespace) {
if (find_header_and_get_info(packet_data, packet_dataLen,
http_useragent_find, &hdr_name_addr,
&hdr_value_addr, &hdr_value_len))
{
useragent_addr = hdr_value_addr;
useragent_len = hdr_value_len;
/* We move Host header value by one byte to the left and then
* "insert" stolen space to the end of User-Agent value because
* some web servers are not tolerant to additional space in the
* end of Host header.
*
* Nothing is done if User-Agent header is missing.
*/
if (useragent_addr && useragent_len > 0) {
/* useragent_addr is in the beginning of User-Agent value */
if (useragent_addr > host_addr) {
/* Move one byte to the LEFT from "Host:"
* to the end of User-Agent
*/
memmove(host_addr - 1, host_addr,
(PVOID)useragent_addr + useragent_len - (PVOID)host_addr);
host_addr -= 1;
/* Put space in the end of User-Agent header */
*(char*)((PVOID)useragent_addr + useragent_len - 1) = ' ';
should_recalc_checksum = 1;
//printf("Replaced Host header!\n");
}
else {
/* User-Agent goes BEFORE Host header */
/* Move one byte to the RIGHT from the end of User-Agent
* to the "Host:"
*/
memmove((PVOID)useragent_addr + useragent_len + 1,
(PVOID)useragent_addr + useragent_len,
(PVOID)host_addr - 1 - ((PVOID)useragent_addr + useragent_len));
/* Put space in the end of User-Agent header */
*(char*)((PVOID)useragent_addr + useragent_len) = ' ';
should_recalc_checksum = 1;
//printf("Replaced Host header!\n");
}
} /* if (host_len <= HOST_MAXLEN && useragent_addr) */
} /* if (find_header_and_get_info http_useragent) */
} /* else if (do_host_removespace) */
} /* if (find_header_and_get_info http_host) */
} /* Handle OUTBOUND packet with data */
} /* Handle TCP packet with data */
/* Else if we got TCP packet without data */
else if (WinDivertHelperParsePacket(packet, packetLen, &ppIpHdr,
NULL, NULL, NULL, &ppTcpHdr, NULL, NULL, NULL)) {
/* If we got INBOUND SYN+ACK packet */
if (addr.Direction == WINDIVERT_DIRECTION_INBOUND &&
ppTcpHdr->Syn == 1 && ppTcpHdr->Ack == 1) {
//printf("Changing Window Size!\n");
/*
* Window Size is changed even if do_fragment_http_persistent
* is enabled as there could be non-HTTP data on port 80
*/
if (do_fragment_http && ppTcpHdr->SrcPort == htons(80)) {
change_window_size(ppTcpHdr, http_fragment_size);
should_recalc_checksum = 1;
}
else if (do_fragment_https && ppTcpHdr->SrcPort != htons(80)) {
change_window_size(ppTcpHdr, https_fragment_size);
should_recalc_checksum = 1;
}
}
}
/* Else if we got UDP packet with data */
else if (do_dns_redirect && WinDivertHelperParsePacket(packet, packetLen, &ppIpHdr,
NULL, NULL, NULL, NULL, &ppUdpHdr, &packet_data, &packet_dataLen)) {
if (addr.Direction == WINDIVERT_DIRECTION_INBOUND) {
if (dns_handle_incoming(ppIpHdr->DstAddr, ppUdpHdr->DstPort,
packet_data, packet_dataLen,
&dns_conn_info))
{
/* Changing source IP and port to the values
* from DNS conntrack */
ppIpHdr->SrcAddr = dns_conn_info.dstip;
ppUdpHdr->DstPort = dns_conn_info.srcport;
ppUdpHdr->SrcPort = dns_conn_info.dstport;
should_recalc_checksum = 1;
}
else {
if (dns_is_dns_packet(packet_data, packet_dataLen, 0))
should_reinject = 0;
if (do_dns_verb && !should_reinject) {
printf("[DNS] Error handling incoming packet: srcport = %hu, dstport = %hu\n",
ntohs(ppUdpHdr->SrcPort), ntohs(ppUdpHdr->DstPort));
}
}
}
else if (addr.Direction == WINDIVERT_DIRECTION_OUTBOUND) {
if (dns_handle_outgoing(ppIpHdr->SrcAddr, ppUdpHdr->SrcPort,
ppIpHdr->DstAddr, ppUdpHdr->DstPort,
packet_data, packet_dataLen))
{
/* Changing destination IP and port to the values
* from configuration */
ppIpHdr->DstAddr = dns_addr;
ppUdpHdr->DstPort = dns_port;
should_recalc_checksum = 1;
}
else {
if (dns_is_dns_packet(packet_data, packet_dataLen, 1))
should_reinject = 0;
if (do_dns_verb && !should_reinject) {
printf("[DNS] Error handling outgoing packet: srcport = %hu, dstport = %hu\n",
ntohs(ppUdpHdr->SrcPort), ntohs(ppUdpHdr->DstPort));
}
}
}
}
if (should_reinject) {
//printf("Re-injecting!\n");
if (should_recalc_checksum) {
WinDivertHelperCalcChecksums(packet, packetLen, 0);
}
else {
WinDivertHelperCalcChecksums(packet, packetLen,
WINDIVERT_HELPER_NO_REPLACE);
}
WinDivertSend(w_filter, packet, packetLen, &addr, NULL);
}
}
else {
// error, ignore
printf("Error receiving packet!\n");
break;
}
}
}
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