NPM-8th ex

8th ex:-

PROGRAM:

#include<unistd.h>

#include<stdio.h>

#include<sys/socket.h>

#include<netinet/ip.h>

#include<netinet/udp.h>

#define PCKT_LEN 8192

struct ipheader

{

unsigned char iph_ihl:5,iph_ver:4;

unsigned char iph_tos;

unsigned short int iph_len;

unsigned short int iph_ident;

unsigned short int iph_offset;

unsigned char iph_ttl;

unsigned char iph_protocol;

unsigned short int iph_chksum;

unsigned int iph_sourceip;

unsigned int iph_destip;

};

struct udpheader

{

unsigned short int udph_srcport;

unsigned short int udph_destport;

unsigned short int udph_len;

unsigned short int udph_chksum;

};

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);

}

int main(int argc,char *argv[])

{

int sd;

char buffer[PCKT_LEN];

struct ipheader *ip=(struct ipheader *)buffer;

struct udpheader  *udp=(struct  udpheader *)(buffer+sizeof(struct ipheader));

struct sockaddr_in sin,din;

int one=1;

const int *val=&one;

memset(buffer,0,PCKT_LEN);

if(argc!=5)

{

printf("-invalid parameters!!!\n");

printf("-usage %s<source hostname/IP><source port><target hostname/IP><target po

rt>\n",argv[0]);

exit(-1);

}

sd=socket(PF_INET,SOCK_RAW,IPPROTO_UDP);

if(sd<0)

{

perror("socket()error");

exit(-1);

}

else

printf("socket()-using SOCK_RAW socket and udp protocol is ok.\n");

sin.sin_family=AF_INET;

din.sin_family=AF_INET;

sin.sin_port=htons(atoi(argv[2]));

din.sin_port=htons(atoi(argv[4]));

sin.sin_addr.s_addr=inet_addr(argv[1]);

din.sin_addr.s_addr=inet_addr(argv[3]);

ip->iph_ihl=5;

ip->iph_ver=4;

ip->iph_tos=16;

ip->iph_len=sizeof(struct ipheader)+sizeof(struct udpheader);

ip->iph_ident=htons(54321);

ip->iph_ttl=64;

ip->iph_protocol=17;

ip->iph_sourceip=inet_addr(argv[1]);

ip->iph_destip=inet_addr(argv[3]);

udp->udph_srcport=htons(atoi(argv[2]));

udp->udph_destport=htons(atoi(argv[4]));

udp->udph_len=htons(sizeof(struct udpheader));

ip->iph_chksum=csum((unsigned short *)buffer,sizeof(struct ipheader)+sizeof(stru

ct udpheader));

if(setsockopt(sd,IPPROTO_IP,IP_HDRINCL,val,sizeof(one))<0)

{

perror("setsockopt()error");

exit(-1);

}

else

printf("setsockopt() is ok.\n");

printf("trying...\n");

printf("using raw socket and udp protocol\n");

printf("using source IP:%u,target IP:%s port:%u \n",argv[1],atoi(argv[2]),argv[3

],atoi(argv[4]));

int count;

for(count=1;count<=20;count++)

{

if(sendto(sd,buffer,ip->iph_len,0,(struct sockaddr *)&sin,sizeof(sin))<0)

{

perror("sendto()error");

exit(-1);

}

else

{

printf("count #%u -sendto() is ok.\n",count);

sleep(2);

}

}

close(sd);

return 0;

}

OUTPUT:

[root@localhost~]#./a.out 172.16.6.4 2345 172.16.6.4 2345
socket()–using SOCK_RAW socket and udp protocol is ok

Setsockopt() is ok

Trying

Using raw socket and udp protocol

Using source ip:172.16.6.4 port:2345 target ip:172.16.6.4 port:2345

Count#1-sentto()is ok

Count#2-sentto()is ok

Count#3-sentto()is ok

Count#4-sentto()is ok

Count#5-sentto()is ok

Count#6-sentto()is ok

Count#7-sentto()is ok

Count#8-sentto()is ok

Count#9-sentto()is ok

Count#10-sentto()is ok

Count#11-sentto()is ok

Count#12-sentto()is ok

Count#13-sentto()is ok

Count#14-sentto()is ok

Count#15-sentto()is ok

Count#16-sentto()is ok

Count#17-sentto()is ok

Count#18-sentto()is ok

Count#19-sentto()is ok

Count#20-sentto()is ok