justuuu

#include<stdio.h>
#include<string.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<arpa/inet.h>
#include<stdlib.h>
#include<unistd.h>
#include<pthread.h>
#define timeoutvalue 5
#define packetcount 10
#define windowsize 3
typedef struct Packet
{
int id;
int send;
}Packet;
Packet packets[packetcount];
pthread_t thread[packetcount],receiveThread;
int sockfd;
struct sockaddr_in addr;
int windowStart,windowEnd;
int nextToSend;
void*sendPacket(void*sendPacket)
{
Packet*packet=(Packet*)sendPacket;
char buffer[1024];
while(packet->send==0)
{
printf("client:sending packet %d\n",packet->id);
bzero(buffer,1024);
sprintf(buffer,"%d",packet->id);
sendto(sockfd,buffer,1024,0,(struct sockaddr*)&addr,sizeof(addr));
sleep(timeoutvalue);
if(packet->send==0)
printf("client:timeout for packet %d\n",packet->id);
}
}
void*receivePacket()
{
socklen_t addr_size=sizeof(addr);
char buffer[1024];
while(1)
{
bzero(buffer,1024);
recvfrom(sockfd,buffer,1024,0,(struct sockaddr*)&addr,&addr_size);
char msg[20];
int packetID;
sscanf(buffer,"%s%d",msg,&packetID);
if(strcmp(msg,"NACK")==0)
{
printf("client received -ve acknowledgement for packet %d \n sending again\n",packetID);
pthread_cancel(thread[packetID-1]);
pthread_create(&thread[packetID-1],NULL,sendPacket,(void*)&packets[packetID-1]);
}
else if(strcmp(msg,"ACK")==0)
{
printf("client:recieved acknowledgemnt for packet %d\n",packetID);
packets[packetID-1].send=1;
if(windowStart==packetID-1)
{
while(packets[windowStart].send==1)
{
windowStart++;
if(windowEnd<packetcount)
windowEnd++;
}
}
}
else
printf("client:invalidmessage\n");
}
}
void main()
{
for(int i=0;i<packetcount;++i)
{
packets[i].id=i+1;
packets[i].send=0;
}
char*ip="127.0.0.100";
int port=5570;
char buffer[1024];
socklen_t addr_size;
sockfd=socket(AF_INET,SOCK_DGRAM,0);
if(sockfd<0)
{
perror("[-]socket error \n");
exit(1);
}
memset(&addr,'\0',sizeof(addr));
addr.sin_family=AF_INET;
addr.sin_port=htons(port);
addr.sin_addr.s_addr=inet_addr(ip);
pthread_create(&receiveThread,NULL,receivePacket,NULL);
windowStart=0;
windowEnd=windowStart+windowsize-1;
for(int i=windowStart;i<=windowEnd;++i)
pthread_create(&thread[i],NULL,sendPacket,(void*)&packets[i]);
nextToSend=windowEnd+1;
while(windowStart!=windowEnd)
{
if(nextToSend<=windowEnd && nextToSend<packetcount)
{
pthread_create(&thread[nextToSend],NULL,sendPacket,(void*)&packets[nextToSend]);
nextToSend++;
}
}
close(sockfd);
}