modify tcp packet payload with Windivert but than connection finished - c

Question

i am working on an project and i need to edit a tcp packet data. I use Windivert for this, I can find my packet and edit also i dont vhange packet length just replace some walues with random values(i try this with socket rediretion and edit it will work but i want to use windivert) but when re-inject this server responde with FIN,ACK Flags. Here is my code, I can' figure out problem if anyone can help me i will be happy.
#include <winsock2.h>
#include <windows.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "windivert.h"
#define MAXBUF WINDIVERT_MTU_MAX
#define PROXY_PORT 34010
#define ALT_PORT 43010
#define MAX_LINE 65
/*
* Proxy server configuration.
*/
typedef struct
{
UINT16 proxy_port;
UINT16 alt_port;
} PROXY_CONFIG, *PPROXY_CONFIG;
typedef struct
{
SOCKET s;
UINT16 alt_port;
struct in_addr dest;
} PROXY_CONNECTION_CONFIG, *PPROXY_CONNECTION_CONFIG;
typedef struct
{
BOOL inbound;
SOCKET s;
SOCKET t;
} PROXY_TRANSFER_CONFIG, *PPROXY_TRANSFER_CONFIG;
/*
* Lock to sync output.
*/
static HANDLE lock;
/*
* Prototypes.
*/
static DWORD proxy(LPVOID arg);
static DWORD proxy_connection_handler(LPVOID arg);
static DWORD proxy_transfer_handler(LPVOID arg);
/*
* Error handling.
*/
static void message(const char *msg, ...)
{
va_list args;
va_start(args, msg);
WaitForSingleObject(lock, INFINITE);
vfprintf(stderr, msg, args);
putc('\n', stderr);
ReleaseMutex(lock);
va_end(args);
}
#define error(msg, ...) \
do { \
message("error: " msg, ## __VA_ARGS__); \
exit(EXIT_FAILURE); \
} while (FALSE)
#define warning(msg, ...) \
message("warning: " msg, ## __VA_ARGS__)
int generate_random(int l, int r) { //this will generate random number in range l and r
int rand_num = (rand() % (r - l + 1)) + l;
return rand_num;
}
/*
* Entry.
*/
int __cdecl main(int argc, char **argv)
{
HANDLE handle, thread;
UINT16 port, proxy_port, alt_port;
int r;
char filter[256];
INT16 priority = 123; // Arbitrary.
PPROXY_CONFIG config;
unsigned char packet[MAXBUF];
UINT packet_len;
WINDIVERT_ADDRESS addr;
PWINDIVERT_IPHDR ip_header;
PWINDIVERT_TCPHDR tcp_header;
DWORD len;
// Init.
if (argc != 2)
{
fprintf(stderr, "usage: %s dest-port\n", argv[0]);
exit(EXIT_FAILURE);
}
port = (UINT16)atoi(argv[1]);
if (port < 0 || port > 0xFFFF)
{
fprintf(stderr, "error: invalid port number (%d)\n", port);
exit(EXIT_FAILURE);
}
proxy_port = (port == PROXY_PORT? PROXY_PORT+1: PROXY_PORT);
alt_port = (port == ALT_PORT? ALT_PORT+1: ALT_PORT);
lock = CreateMutex(NULL, FALSE, NULL);
if (lock == NULL)
{
fprintf(stderr, "error: failed to create mutex (%d)\n",
GetLastError());
exit(EXIT_FAILURE);
}
// Divert all traffic to/from `port', `proxy_port' and `alt_port'.
r = snprintf(filter, sizeof(filter),
"tcp and "
"(tcp.DstPort == %d or tcp.DstPort == %d or tcp.DstPort == %d or "
"tcp.SrcPort == %d or tcp.SrcPort == %d or tcp.SrcPort == %d)",
port, proxy_port, alt_port, port, proxy_port, alt_port);
if (r < 0 || r >= sizeof(filter))
{
error("failed to create filter string");
}
handle = WinDivertOpen(filter, WINDIVERT_LAYER_NETWORK, priority, 0);
if (handle == INVALID_HANDLE_VALUE)
{
error("failed to open the WinDivert device (%d)", GetLastError());
}
// Spawn proxy thread,
config = (PPROXY_CONFIG)malloc(sizeof(PROXY_CONFIG));
if (config == NULL)
{
error("failed to allocate memory");
}
config->proxy_port = proxy_port;
config->alt_port = alt_port;
thread = CreateThread(NULL, 1, (LPTHREAD_START_ROUTINE)proxy,
(LPVOID)config, 0, NULL);
if (thread == NULL)
{
error("failed to create thread (%d)", GetLastError());
}
CloseHandle(thread);
// Main loop:
while (TRUE)
{
if (!WinDivertRecv(handle, packet, sizeof(packet), &packet_len, &addr))
{
warning("failed to read packet (%d)", GetLastError());
continue;
}
WinDivertHelperParsePacket(packet, packet_len, &ip_header, NULL, NULL,
NULL, NULL, &tcp_header, NULL, NULL, NULL, NULL, NULL);
if (ip_header == NULL || tcp_header == NULL)
{
warning("failed to parse packet (%d)", GetLastError());
continue;
}
if (addr.Outbound)
{
if (tcp_header->DstPort == htons(port))
{
// Reflect: PORT ---> PROXY
UINT32 dst_addr = ip_header->DstAddr;
tcp_header->DstPort = htons(proxy_port);
ip_header->DstAddr = ip_header->SrcAddr;
ip_header->SrcAddr = dst_addr;
addr.Outbound = FALSE;
if ((UINT8)packet[40] == 128 && (UINT8)packet[41] == 0 && (UINT8)packet[42] == 119 && (UINT8)packet[43] == 162 && (UINT8)packet[172] == 185)
{
srand(time(0));
printf(" \n founded \n");
(UINT8)packet[168] = generate_random(1, 155);
(UINT8)packet[172] = generate_random(1, 155);
WinDivertHelperCalcChecksums(packet, packet_len, &addr, 0);
if (!WinDivertSend(handle, packet, packet_len, NULL, &addr))
{
// Handle send error
continue;
}
}
}
else if (tcp_header->SrcPort == htons(proxy_port))
{
// Reflect: PROXY ---> PORT
UINT32 dst_addr = ip_header->DstAddr;
tcp_header->SrcPort = htons(port);
ip_header->DstAddr = ip_header->SrcAddr;
ip_header->SrcAddr = dst_addr;
addr.Outbound = FALSE;
}
else if (tcp_header->DstPort == htons(alt_port))
{
// Redirect: ALT ---> PORT
tcp_header->DstPort = htons(port);
}
}
else
{
if (tcp_header->SrcPort == htons(port))
{
// Redirect: PORT ---> ALT
tcp_header->SrcPort = htons(alt_port);
}
}
WinDivertHelperCalcChecksums(packet, packet_len, &addr, 0);
if (!WinDivertSend(handle, packet, packet_len, NULL, &addr))
{
warning("failed to send packet (%d)", GetLastError());
continue;
}
}
return 0;
}
/*
* Proxy server thread.
*/
static DWORD proxy(LPVOID arg)
{
PPROXY_CONFIG config = (PPROXY_CONFIG)arg;
UINT16 proxy_port = config->proxy_port;
UINT16 alt_port = config->alt_port;
int on = 1;
WSADATA wsa_data;
WORD wsa_version = MAKEWORD(2, 2);
struct sockaddr_in addr;
SOCKET s;
HANDLE thread;
free(config);
if (WSAStartup(wsa_version, &wsa_data) != 0)
{
error("failed to start WSA (%d)", GetLastError());
}
s = socket(AF_INET, SOCK_STREAM, 0);
if (s == INVALID_SOCKET)
{
error("failed to create socket (%d)", WSAGetLastError());
}
if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char*)&on, sizeof(int))
== SOCKET_ERROR)
{
error("failed to re-use address (%d)", GetLastError());
}
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(proxy_port);
if (bind(s, (SOCKADDR *)&addr, sizeof(addr)) == SOCKET_ERROR)
{
error("failed to bind socket (%d)", WSAGetLastError());
}
if (listen(s, 16) == SOCKET_ERROR)
{
error("failed to listen socket (%d)", WSAGetLastError());
}
while (TRUE)
{
// Wait for a new connection.
PPROXY_CONNECTION_CONFIG config;
int size = sizeof(addr);
SOCKET t = accept(s, (SOCKADDR *)&addr, &size);
if (t == INVALID_SOCKET)
{
warning("failed to accept socket (%d)", WSAGetLastError());
continue;
}
// Spawn proxy connection handler thread.
config = (PPROXY_CONNECTION_CONFIG)
malloc(sizeof(PROXY_CONNECTION_CONFIG));
if (config == NULL)
{
error("failed to allocate memory");
}
config->s = t;
config->alt_port = alt_port;
config->dest = addr.sin_addr;
thread = CreateThread(NULL, 1,
(LPTHREAD_START_ROUTINE)proxy_connection_handler,
(LPVOID)config, 0, NULL);
if (thread == NULL)
{
warning("failed to create thread (%d)", GetLastError());
closesocket(t);
free(config);
continue;
}
CloseHandle(thread);
}
}
/*
* Proxy connection handler thread.
*/
static DWORD proxy_connection_handler(LPVOID arg)
{
PPROXY_TRANSFER_CONFIG config1, config2;
HANDLE thread;
PPROXY_CONNECTION_CONFIG config = (PPROXY_CONNECTION_CONFIG)arg;
SOCKET s = config->s, t;
UINT16 alt_port = config->alt_port;
struct in_addr dest = config->dest;
struct sockaddr_in addr;
free(config);
t = socket(AF_INET, SOCK_STREAM, 0);
if (t == INVALID_SOCKET)
{
warning("failed to create socket (%d)", WSAGetLastError());
closesocket(s);
return 0;
}
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(alt_port);
addr.sin_addr = dest;
if (connect(t, (SOCKADDR *)&addr, sizeof(addr)) == SOCKET_ERROR)
{
warning("failed to connect socket (%d)", WSAGetLastError());
closesocket(s);
closesocket(t);
return 0;
}
config1 = (PPROXY_TRANSFER_CONFIG)malloc(sizeof(PROXY_TRANSFER_CONFIG));
config2 = (PPROXY_TRANSFER_CONFIG)malloc(sizeof(PROXY_TRANSFER_CONFIG));
if (config1 == NULL || config2 == NULL)
{
error("failed to allocate memory");
}
config1->inbound = FALSE;
config2->inbound = TRUE;
config2->t = config1->s = s;
config2->s = config1->t = t;
thread = CreateThread(NULL, 1,
(LPTHREAD_START_ROUTINE)proxy_transfer_handler, (LPVOID)config1, 0,
NULL);
if (thread == NULL)
{
warning("failed to create thread (%d)", GetLastError());
closesocket(s);
closesocket(t);
free(config1);
free(config2);
return 0;
}
proxy_transfer_handler((LPVOID)config2);
WaitForSingleObject(thread, INFINITE);
CloseHandle(thread);
closesocket(s);
closesocket(t);
return 0;
}
/*
* Handle the transfer of data from one socket to another.
*/
static DWORD proxy_transfer_handler(LPVOID arg)
{
PPROXY_TRANSFER_CONFIG config = (PPROXY_TRANSFER_CONFIG)arg;
BOOL inbound = config->inbound;
SOCKET s = config->s, t = config->t;
char buf[8192];
int len, len2, i;
HANDLE console;
free(config);
while (TRUE)
{
1
len = recv(s, buf, sizeof(buf), 0);
if (len == SOCKET_ERROR)
{
warning("failed to recv from socket (%d)", WSAGetLastError());
shutdown(s, SD_BOTH);
shutdown(t, SD_BOTH);
return 0;
}
if (len == 0)
{
shutdown(s, SD_RECEIVE);
shutdown(t, SD_SEND);
return 0;
}
// Dump stream information to the screen.
console = GetStdHandle(STD_OUTPUT_HANDLE);
WaitForSingleObject(lock, INFINITE);
printf("[%.4d] ", len);
SetConsoleTextAttribute(console,
(inbound? FOREGROUND_RED: FOREGROUND_GREEN));
for (i = 0; i < len && i < MAX_LINE; i++)
{
putchar((isprint(buf[i])? buf[i]: '.'));
}
SetConsoleTextAttribute(console,
FOREGROUND_RED | FOREGROUND_GREEN | FOREGROUND_BLUE);
printf("%s\n", (len > MAX_LINE? "...": ""));
ReleaseMutex(lock);
// Send data to t.
int i;
for (i = 0; i < len; )
{
len2 = send(t, buf+i, len-i, 0);
if (len2 == SOCKET_ERROR)
{
warning("failed to send to socket (%d)", WSAGetLastError());
shutdown(s, SD_BOTH);
shutdown(t, SD_BOTH);
return 0;
}
i += len2;
}
}
return 0;
}
wireshark outputs are here ;
When i don't edit packet here is wireshark output;
Wireshark Output without edit
When I try to edit packet it is edited but wireshark output is like that (editted packets length is 188);
Wireshark Output With Edit