static short tamperProcess(PacketNode *head, PacketNode *tail) {
short tampered = FALSE;
PacketNode *pac = head->next;
while (pac != tail) {
if (checkDirection(pac->addr.Direction, tamperInbound, tamperOutbound)
&& calcChance(chance)) {
char *data = NULL;
UINT dataLen = 0;
if (DivertHelperParsePacket(pac->packet, pac->packetLen, NULL, NULL, NULL,
NULL, NULL, NULL, (PVOID*)&data, &dataLen)
&& data != NULL && dataLen != 0) {
// trying to tamper the more center part of the packet,
// since common packets put their checksum at head or tail
if (dataLen <= 4) {
// for short packet just tamper it all
tamper_buf(data, dataLen);
LOG("tampered w/ chance %.1f, dochecksum: %d, short packet changed all", chance/10.0, doChecksum);
} else {
// for longer ones process 1/4 of the lens start somewhere in the middle
UINT len = dataLen;
UINT len_d4 = len / 4;
tamper_buf(data + len/2 - len_d4/2 + 1, len_d4);
LOG("tampered w/ chance %.1f, dochecksum: %d, changing %d bytes out of %u", chance/10.0, doChecksum, len_d4, len);
}
// FIXME checksum seems to have some problem
if (doChecksum) {
DivertHelperCalcChecksums(pac->packet, pac->packetLen, 0);
}
tampered = TRUE;
}
}
pac = pac->next;
}
return tampered;
}
/*
* Entry.
*/
int __cdecl main(int argc, char **argv)
{
HANDLE handle, console;
UINT i;
INT16 priority = 0;
char packet[MAXBUF];
UINT packet_len;
DIVERT_ADDRESS recv_addr, send_addr;
PDIVERT_IPHDR ip_header;
PDIVERT_IPV6HDR ipv6_header;
PDIVERT_ICMPHDR icmp_header;
PDIVERT_ICMPV6HDR icmpv6_header;
PDIVERT_TCPHDR tcp_header;
PDIVERT_UDPHDR udp_header;
UINT payload_len;
TCPPACKET reset0;
PTCPPACKET reset = &reset0;
UINT8 dnr0[sizeof(ICMPPACKET) + 0x0F*sizeof(UINT32) + 8 + 1];
PICMPPACKET dnr = (PICMPPACKET)dnr0;
TCPV6PACKET resetv6_0;
PTCPV6PACKET resetv6 = &resetv6_0;
UINT8 dnrv6_0[sizeof(ICMPV6PACKET) + sizeof(DIVERT_IPV6HDR) +
sizeof(DIVERT_TCPHDR)];
PICMPV6PACKET dnrv6 = (PICMPV6PACKET)dnrv6_0;
// Check arguments.
switch (argc)
{
case 2:
break;
case 3:
priority = (INT16)atoi(argv[2]);
break;
default:
fprintf(stderr, "usage: %s divert-filter [priority]\n",
argv[0]);
fprintf(stderr, "examples:\n");
fprintf(stderr, "\t%s true\n", argv[0]);
fprintf(stderr, "\t%s \"outbound and tcp.DstPort == 80\" 1000\n",
argv[0]);
fprintf(stderr, "\t%s \"inbound and tcp.Syn\" -4000\n", argv[0]);
exit(EXIT_FAILURE);
}
// Initialize all packets.
PacketIpTcpInit(reset);
reset->tcp.Rst = 1;
reset->tcp.Ack = 1;
PacketIpIcmpInit(dnr);
dnr->icmp.Type = 3; // Destination not reachable.
dnr->icmp.Code = 3; // Port not reachable.
PacketIpv6TcpInit(resetv6);
resetv6->tcp.Rst = 1;
resetv6->tcp.Ack = 1;
PacketIpv6Icmpv6Init(dnrv6);
dnrv6->ipv6.Length = htons(sizeof(DIVERT_ICMPV6HDR) + 4 +
sizeof(DIVERT_IPV6HDR) + sizeof(DIVERT_TCPHDR));
dnrv6->icmpv6.Type = 1; // Destination not reachable.
dnrv6->icmpv6.Code = 4; // Port not reachable.
// Get console for pretty colors.
console = GetStdHandle(STD_OUTPUT_HANDLE);
// Divert traffic matching the filter:
handle = DivertOpen(argv[1], 0, priority, 0);
if (handle == INVALID_HANDLE_VALUE)
{
if (GetLastError() == ERROR_INVALID_PARAMETER)
{
fprintf(stderr, "error: filter syntax error\n");
exit(EXIT_FAILURE);
}
fprintf(stderr, "error: failed to open Divert device (%d)\n",
GetLastError());
exit(EXIT_FAILURE);
}
// Main loop:
while (TRUE)
{
// Read a matching packet.
if (!DivertRecv(handle, packet, sizeof(packet), &recv_addr,
&packet_len))
{
fprintf(stderr, "warning: failed to read packet\n");
continue;
}
// Print info about the matching packet.
DivertHelperParse(packet, packet_len, &ip_header, &ipv6_header,
&icmp_header, &icmpv6_header, &tcp_header, &udp_header, NULL,
&payload_len);
if (ip_header == NULL && ipv6_header == NULL)
{
continue;
}
// Dump packet info:
SetConsoleTextAttribute(console, FOREGROUND_RED);
fputs("BLOCK ", stdout);
SetConsoleTextAttribute(console,
FOREGROUND_RED | FOREGROUND_GREEN | FOREGROUND_BLUE);
if (ip_header != NULL)
{
UINT8 *src_addr = (UINT8 *)&ip_header->SrcAddr;
UINT8 *dst_addr = (UINT8 *)&ip_header->DstAddr;
printf("ip.SrcAddr=%u.%u.%u.%u ip.DstAddr=%u.%u.%u.%u ",
src_addr[0], src_addr[1], src_addr[2], src_addr[3],
dst_addr[0], dst_addr[1], dst_addr[2], dst_addr[3]);
}
if (ipv6_header != NULL)
{
UINT16 *src_addr = (UINT16 *)&ipv6_header->SrcAddr;
UINT16 *dst_addr = (UINT16 *)&ipv6_header->DstAddr;
fputs("ipv6.SrcAddr=", stdout);
for (i = 0; i < 8; i++)
{
printf("%x%c", ntohs(src_addr[i]), (i == 7? ' ': ':'));
}
fputs(" ipv6.DstAddr=", stdout);
for (i = 0; i < 8; i++)
{
printf("%x%c", ntohs(dst_addr[i]), (i == 7? ' ': ':'));
}
putchar(' ');
}
if (icmp_header != NULL)
{
printf("icmp.Type=%u icmp.Code=%u ",
icmp_header->Type, icmp_header->Code);
// Simply drop ICMP
}
if (icmpv6_header != NULL)
{
printf("icmpv6.Type=%u icmpv6.Code=%u ",
icmpv6_header->Type, icmpv6_header->Code);
// Simply drop ICMPv6
}
if (tcp_header != NULL)
{
printf("tcp.SrcPort=%u tcp.DstPort=%u tcp.Flags=",
ntohs(tcp_header->SrcPort), ntohs(tcp_header->DstPort));
if (tcp_header->Fin)
{
fputs("[FIN]", stdout);
}
if (tcp_header->Rst)
{
fputs("[RST]", stdout);
}
if (tcp_header->Urg)
{
fputs("[URG]", stdout);
}
if (tcp_header->Syn)
{
fputs("[SYN]", stdout);
}
if (tcp_header->Psh)
{
fputs("[PSH]", stdout);
}
if (tcp_header->Ack)
{
fputs("[ACK]", stdout);
}
putchar(' ');
if (ip_header != NULL)
{
reset->ip.SrcAddr = ip_header->DstAddr;
reset->ip.DstAddr = ip_header->SrcAddr;
reset->tcp.SrcPort = tcp_header->DstPort;
reset->tcp.DstPort = tcp_header->SrcPort;
reset->tcp.SeqNum =
(tcp_header->Ack? tcp_header->AckNum: 0);
reset->tcp.AckNum =
(tcp_header->Syn?
htonl(ntohl(tcp_header->SeqNum) + 1):
htonl(ntohl(tcp_header->SeqNum) + payload_len));
DivertHelperCalcChecksums((PVOID)reset, sizeof(TCPPACKET), 0);
memcpy(&send_addr, &recv_addr, sizeof(send_addr));
send_addr.Direction = !recv_addr.Direction;
if (!DivertSend(handle, (PVOID)reset, sizeof(TCPPACKET),
&send_addr, NULL))
{
fprintf(stderr, "warning: failed to send TCP reset (%d)\n",
GetLastError());
}
}
if (ipv6_header != NULL)
{
memcpy(resetv6->ipv6.SrcAddr, ipv6_header->DstAddr,
sizeof(resetv6->ipv6.SrcAddr));
memcpy(resetv6->ipv6.DstAddr, ipv6_header->SrcAddr,
sizeof(resetv6->ipv6.DstAddr));
resetv6->tcp.SrcPort = tcp_header->DstPort;
resetv6->tcp.DstPort = tcp_header->SrcPort;
resetv6->tcp.SeqNum =
(tcp_header->Ack? tcp_header->AckNum: 0);
resetv6->tcp.AckNum =
(tcp_header->Syn?
htonl(ntohl(tcp_header->SeqNum) + 1):
htonl(ntohl(tcp_header->SeqNum) + payload_len));
DivertHelperCalcChecksums((PVOID)resetv6, sizeof(TCPV6PACKET),
0);
memcpy(&send_addr, &recv_addr, sizeof(send_addr));
send_addr.Direction = !recv_addr.Direction;
if (!DivertSend(handle, (PVOID)resetv6, sizeof(TCPV6PACKET),
&send_addr, NULL))
{
fprintf(stderr, "warning: failed to send TCP (IPV6) "
"reset (%d)\n", GetLastError());
}
}
}
if (udp_header != NULL)
{
printf("udp.SrcPort=%u udp.DstPort=%u ",
ntohs(udp_header->SrcPort), ntohs(udp_header->DstPort));
if (ip_header != NULL)
{
// NOTE: For some ICMP error messages, WFP does not seem to
// support INBOUND injection. As a work-around, we
// always inject OUTBOUND.
UINT icmp_length = ip_header->HdrLength*sizeof(UINT32) + 8;
memcpy(dnr->data, ip_header, icmp_length);
icmp_length += sizeof(ICMPPACKET);
dnr->ip.Length = htons((UINT16)icmp_length);
dnr->ip.SrcAddr = ip_header->DstAddr;
dnr->ip.DstAddr = ip_header->SrcAddr;
DivertHelperCalcChecksums((PVOID)dnr, icmp_length, 0);
memcpy(&send_addr, &recv_addr, sizeof(send_addr));
send_addr.Direction = DIVERT_DIRECTION_OUTBOUND;
if (!DivertSend(handle, (PVOID)dnr, icmp_length, &send_addr,
NULL))
{
fprintf(stderr, "warning: failed to send ICMP message "
"(%d)\n", GetLastError());
}
}
if (ipv6_header != NULL)
{
UINT icmpv6_length = sizeof(DIVERT_IPV6HDR) +
sizeof(DIVERT_TCPHDR);
memcpy(dnrv6->data, ipv6_header, icmpv6_length);
icmpv6_length += sizeof(ICMPV6PACKET);
memcpy(dnrv6->ipv6.SrcAddr, ipv6_header->DstAddr,
sizeof(dnrv6->ipv6.SrcAddr));
memcpy(dnrv6->ipv6.DstAddr, ipv6_header->SrcAddr,
sizeof(dnrv6->ipv6.DstAddr));
DivertHelperCalcChecksums((PVOID)dnrv6, icmpv6_length, 0);
memcpy(&send_addr, &recv_addr, sizeof(send_addr));
send_addr.Direction = DIVERT_DIRECTION_OUTBOUND;
if (!DivertSend(handle, (PVOID)dnrv6, icmpv6_length,
&send_addr, NULL))
{
fprintf(stderr, "warning: failed to send ICMPv6 message "
"(%d)\n", GetLastError());
}
}
}
putchar('\n');
}
}
