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GoodbyeDPI
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Serious refactoring

This commit is contained in:
ValdikSS 2017-12-04 22:01:25 +03:00
parent 87c354addf
commit da1e2e8aac
1 changed files with 94 additions and 69 deletions
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163
goodbyedpi.c
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@ -4,6 +4,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>
@ -15,7 +16,7 @@
sleep(10); exit(EXIT_FAILURE); } while (0)
#define MAX_FILTERS 4
#define MAX_PACKET_SIZE 1516
#define MAX_PACKET_SIZE 9016
#define IPV4_HDR_LEN 20
#define TCP_HDR_LEN 20
#define IPV4_TOTALLEN_OFFSET 2
@ -57,7 +58,7 @@ static const char *http_methods[] = {
static char* dumb_memmem(const char* haystack, int hlen, const char* needle, int nlen) {
// naive implementation
if (nlen > hlen) return 0;
if (nlen > hlen) return NULL;
int i;
for (i=0; i<hlen-nlen+1; i++) {
if (memcmp(haystack+i,needle,nlen)==0) {
@ -83,9 +84,9 @@ static HANDLE init(char *filter, UINT64 flags) {
static int deinit(HANDLE handle) {
if (handle) {
WinDivertClose(handle);
return 1;
return TRUE;
}
return 0;
return FALSE;
}
static void deinit_all() {
@ -107,26 +108,49 @@ static int is_passivedpi_redirect(const char *pktdata, int pktlen) {
/* 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 1;
return TRUE;
}
}
return 0;
return FALSE;
}
/* Finds Host header with \r\n before it */
static PVOID find_host_header(const char *pktdata, int pktlen) {
return dumb_memmem(pktdata, pktlen,
http_host_find, strlen(http_host_find));
}
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;
/* Finds User-Agent header with \r\n before it */
static PVOID find_useragent_header(const char *pktdata, int pktlen) {
return dumb_memmem(pktdata, pktlen,
http_useragent_find, strlen(http_useragent_find));
*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 void change_window_size(const char *pkt, int size) {
*(uint16_t*)(pkt + IPV4_HDR_LEN + TCP_WINDOWSIZE_OFFSET) = htons(size);
if (size >= 1 && size <= 65535) {
*(uint16_t*)(pkt + IPV4_HDR_LEN + TCP_WINDOWSIZE_OFFSET) = htons(size);
}
}
/* HTTP method end without trailing space */
@ -167,8 +191,11 @@ int main(int argc, char *argv[]) {
do_host_removespace = 0, do_additional_space = 0;
int http_fragment_size = 2;
int https_fragment_size = 2;
char *data_addr, *data_addr_rn, *host_addr, *useragent_addr, *method_addr;
int data_len, host_len;
char *host_addr, *useragent_addr, *method_addr;
int host_len, useragent_len;
char *hdr_name_addr = NULL, *hdr_value_addr = NULL;
int hdr_value_len;
printf("GoodbyeDPI: Passive DPI blocker and Active DPI circumvention utility\n");
@ -316,7 +343,7 @@ int main(int argc, char *argv[]) {
should_reinject = 0;
}
}
/* Handle OUTBOUND packet, search for Host header */
/* Handle OUTBOUND packet on port 80, search for Host header */
else if (addr.Direction == WINDIVERT_DIRECTION_OUTBOUND &&
packet_dataLen > 16 && ppTcpHdr->DstPort == htons(80) &&
find_http_method_end(packet_data,
@ -324,34 +351,42 @@ int main(int argc, char *argv[]) {
(do_host || do_host_removespace))
{
data_addr = find_host_header(packet_data, packet_dataLen);
if (data_addr) {
/* 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)) {
host_addr = hdr_value_addr;
host_len = hdr_value_len;
if (do_host) {
/* Replace "Host: " with "hoSt: " */
memcpy(data_addr, http_host_replace, strlen(http_host_replace));
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 */
host_addr = data_addr + strlen(http_host_find) - 1;
method_addr = find_http_method_end(packet_data,
(do_fragment_http ? http_fragment_size : 0));
if (method_addr) {
memmove(method_addr + 1, method_addr, (PVOID)host_addr - (PVOID)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) {
host_addr = data_addr + strlen(http_host_find);
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;
data_addr_rn = dumb_memmem(host_addr,
packet_dataLen - ((PVOID)host_addr - packet_data),
"\r\n", 2);
if (data_addr_rn) {
/* 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
@ -359,58 +394,48 @@ int main(int argc, char *argv[]) {
*
* Nothing is done if User-Agent header is missing.
*/
host_len = data_addr_rn - host_addr;
useragent_addr = find_useragent_header(packet_data, packet_dataLen);
if (host_len <= 253 && useragent_addr) {
useragent_addr += strlen(http_useragent_find);
if (host_len > 0 && host_len <= 253 &&
useragent_addr && useragent_len > 0) {
/* useragent_addr is in the beginning of User-Agent value */
data_len = packet_dataLen - ((PVOID)useragent_addr - packet_data);
data_addr_rn = dumb_memmem(useragent_addr,
data_len, "\r\n", 2);
/* data_addr_rn is in the end 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, useragent_len);
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 */
if (data_addr_rn) {
if (useragent_addr > host_addr) {
/* User-Agent goes AFTER Host header */
data_len = (PVOID)data_addr_rn - (PVOID)host_addr;
/* Move one byte to the LEFT from "Host:"
* to the end of User-Agent
*/
memmove(host_addr - 1, host_addr, data_len);
/* Put space in the end of User-Agent header */
*(char*)(data_addr_rn - 1) = ' ';
should_recalc_checksum = 1;
//printf("Replaced Host header!\n");
}
else {
/* User-Agent goes BEFORE Host header */
data_len = (PVOID)host_addr - (PVOID)data_addr_rn - 1;
/* Move one byte to the RIGHT from the end of User-Agent
* to the "Host:"
*/
memmove(data_addr_rn + 1, data_addr_rn, data_len);
/* Put space in the end of User-Agent header */
*(char*)(data_addr_rn) = ' ';
should_recalc_checksum = 1;
//printf("Replaced Host header!\n");
}
} /* if (dara_addr_rn) */
/* 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,
useragent_len - 1);
/* 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 <= 253 && useragent_addr) */
} /* if (data_addr_rn) */
} /* if (find_header_and_get_info http_useragent) */
} /* else if (do_host_removespace) */
} /* if (data_addr) */
} /* if (find_header_and_get_info http_host) */
} /* Handle OUTBOUND packet with data */
} /* Handle 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 SYN+ACK packet */
/* If we got INBOUND SYN+ACK packet */
if (addr.Direction == WINDIVERT_DIRECTION_INBOUND &&
ppTcpHdr->Syn == 1) {
ppTcpHdr->Syn == 1 && ppTcpHdr->Ack == 1) {
//printf("Changing Window Size!\n");
if (do_fragment_http && ppTcpHdr->SrcPort == htons(80)) {
change_window_size(packet, http_fragment_size);