/* Program for Master */

/* Header files */

#include<stdio.h>

#include<stdlib.h>

#include<pcap.h>

#include<netinet/in.h>

#include<arpa/inet.h>

#include<netinet/if_ether.h>

#include <linux/if_packet.h>

#include <linux/if_ether.h>

#include<string.h>

#include<sys/types.h>

#include<sys/time.h>

#include<signal.h>

#define TIMEOUT_SECS 10

struct timespec t,t1;

struct timeval t2,t3;

unsigned char* packet;

pcap_t *descr;

int len;

struct ethhdr *eth;

/* Function handlet for SIGALRM */

void CatchAlarm(int signum)

{

printf("\n\t\tTIMEOUT :-(\n");

pcap_breakloop(descr);

pcap_close(descr);

}

/* end of function */

void ether_head()

{

/* Source address (Master) */

eth->h_source[0]=0x00;

eth->h_source[1]=0x1F;

eth->h_source[2]=0xD0;

eth->h_source[3]=0x3F;

eth->h_source[4]=0x28;

eth->h_source[5]=0x52;

eth->h_proto=0x00;

memcpy(packet,eth,len);

}

/* end of function */

void my_callback(u_char *useless,const struct pcap_pkthdr* pkthdr,const u_char* packet)

{

char str[100],*p,*q,str1[100],s_dest[200];

int id;

int len1=6,j=0;

const u_char *p1=packet ;

p = (char *)malloc(100);

q = (char *)malloc(100);

p1+=6;

strcpy(str,packet+14);

p = strtok(str," ");

if(strcmp(p,"INIT")!=0)

{

q = strtok(NULL,"\0");

strcpy(str1,q);

}

if(strcmp(p,"SYN")==0)

{

strcpy(q,str1);

q=strtok(q,".");

strcpy(str1,q);

id=atoi(str1);

if(id ==2)

{

t.tv_sec = pkthdr->ts.tv_sec;

t.tv_nsec = pkthdr->ts.tv_usec;

}

}

else if(strcmp(p,"REP") == 0)

{

strcpy(q,str1);

q=strtok(q,".");

strcpy(str1,q);

id=atoi(str1);

}

else if(strcmp(p,"INIT")==0)

{

printf("\n\t\tReceived INIT packet....\n");

while(len1--)

{

eth->h_dest[j]=*p1;

p1++,j++;

}

}

else

printf("\n\t\tother packet\n\n");

}

/* end of function */

/* main function */

int main()

{

char *dev;

char erbuf[PCAP_ERRBUF_SIZE];

struct timeval tim;

struct pcap_pkthdr hdr;

char *point;

char str1[50];

int i=0,j=0,counter=0;

char ptr[200];

pcap_t *descr1;

/* For setting signal handler */

struct sigaction myAction;

struct itimerval timer;

eth=(struct ethhdr *)malloc(sizeof(struct ethhdr));

len=sizeof(struct ethhdr);

strcpy(str1,"\0");

packet=(char*)malloc(1514);

point=(char *)malloc(100);

dev=pcap_lookupdev(erbuf);

if(dev==NULL)

{

printf("\n\t\terrbuf : %s\n\n",erbuf);

exit(1);

}

descr=pcap_open_live(dev,BUFSIZ,0,-1,erbuf);

if(descr==NULL)

{

printf("\n\t\tCannot open:%s\n",erbuf);

exit(1);

}

do

{

printf("\n\t\tWaiting for INIT packet from client : %d \n",counter+1);

i=pcap_loop(descr,1,my_callback,NULL);// wait for INIT packet

ether_head();

strcpy(str1,"\0");

strcpy(str1,"SYN 1.");

memcpy(packet+14,str1,sizeof(str1));

printf("\n\t\tSending SYNC packet to client : %d\n",counter+1);

counter++;

/* Send sync packet containing T1 */

i=pcap_sendpacket(descr,packet,1514);

if(i==-1)

{

pcap_perror(descr,ptr);

printf("\n\t\tERROR : %s\n",ptr);

printf("\n\t\tError in inject function!!!\n");

}

memset(&myAction,0,sizeof(struct sigaction));

myAction.sa_handler = CatchAlarm;

/* block everything in handler */

if (sigfillset(&myAction.sa_mask) < 0)

printf("sigfillset() failed");

myAction.sa_flags = 0;

if (sigaction(SIGALRM, &myAction, 0) < 0)

printf("sigaction() failed for SIGALRM");

alarm(TIMEOUT_SECS);

pcap_setdirection(descr,PCAP_D_IN);

/* Wait for packet containig loop for T3 */

i=pcap_loop(descr,1,my_callback,NULL);

if(i==-1)

printf("\n\n\t\tError in pcap_loop\n");

else if(i==-2)

{

strcpy(str1,"\0");

strcpy(str1,"ERROR "); //new

descr1=pcap_open_live(dev,BUFSIZ,0,-1,erbuf);

if(descr1==NULL)

{

printf("\n\t\tCannot open:%s\n",erbuf);

exit(1);

}

memcpy(packet+14,str1,sizeof(str1));

i=pcap_sendpacket(descr1,packet,1514); /* Sending error packet */

if(i==-1)

pcap_perror(descr1,point);

printf("\n\t\tT3 not received... exiting\n");

continue;

pcap_close(descr1);

}

else

{

alarm(0);

printf("\n\t\tDelay request packet received in time\n");

}

ether_head();

//T4 time sent

strcpy(str1,"\0");

strcpy(str1,"SYN 3.");

memcpy(packet+14,str1,sizeof(str1));

sprintf(str1,"%ld.%ld",t.tv_sec,t.tv_nsec);

memcpy(packet+20,str1,sizeof(str1));

i=pcap_sendpacket(descr,packet,1514); //sending T4

if(i==-1)

printf("\n\n\t\tError in sending Delay response packet\n");

/* Set signal handler for alarm signal */

myAction.sa_handler = CatchAlarm;

if (sigfillset(&myAction.sa_mask) < 0) /* block everything in handler */

printf("sigfillset() failed");

myAction.sa_flags = 0;

if (sigaction(SIGALRM, &myAction, 0) < 0)

printf("sigaction() failed for SIGALRM");

alarm(TIMEOUT_SECS);

pcap_setdirection(descr,PCAP_D_IN);

i=pcap_loop(descr,1,my_callback,NULL); //T4 reply

if(i==-1)

printf("\n\t\tError in pcap_loop()\n");

else if(i==-2)

{

strcpy(str1,"\0");

strcpy(str1,"ERROR "); //new

memcpy(packet+14,str1,sizeof(str1));

i=pcap_sendpacket(descr,packet,1514); //sending error

printf("\n\t\tT4 reply not received... exiting\n\n");

continue;

}

else

{

alarm(0);

printf("\n\t\tT4 reply received in time\n");

printf("\n\t\tClient %d : Request satisfied!!!\n\n\n\n\n",counter);

}

}while(1);

return 0;

}