go_n_client.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
void main()
 {
	int cli_sock, i, j, flag = 1, note = 1;
	char msg1[50] = "ACK", write_buff[50], read_buff[100];
	struct sockaddr_in client;
	cli_sock = socket(AF_INET, SOCK_STREAM, 0);
	memset(&client, 0, sizeof(client));
	client.sin_family = AF_INET;
	client.sin_port = htons(7004);
	client.sin_addr.s_addr = inet_addr("127.0.0.1");
	if (connect(cli_sock, (struct sockaddr *)&client, sizeof(client)) == -1)
       {
	printf("Connection failed");
	exit(0);
	}
	printf("\nReceiver of Go Back N where N = 8\n\n");
	for (i = 0; i < 8; i++)
        {
		memset(&read_buff, 0, sizeof(read_buff));
		memset(&write_buff, 0, sizeof(write_buff));
		if (i == 5 && flag == 1)
	       {
			flag = 0;
			read(cli_sock, read_buff, sizeof(read_buff));
		}
		read(cli_sock, read_buff, sizeof(read_buff));
		if (read_buff[strlen(read_buff) - 1] != i + '0')
	        {
			printf("\n --- Packet from Sender %d Lost - %d Received Out of Order - Discarding ---\n", i, i + 1);
			i--;
		}
		else 
		{
			if (i == 0)
		       {
			printf("-> %s\n", read_buff);
			read(cli_sock, read_buff, sizeof(read_buff));
			i++;
			}
			printf("-> %s\n", read_buff);
			if ((i == 5) || (i == 3)) 
			{
			read(cli_sock, read_buff, sizeof(read_buff));
			printf("-> %s\n", read_buff);
			i++;
			}
			if (i == 7)
			{
			 j = 0;
			}
			else
			{
			j = i + 1;
			}
			if ((i == 6) || (i == 4) || (i == 1))
			printf("<- ACK %d - Cumulative Acknowledgement\n", j);
			else
			printf("<- ACK %d - Individual Acknowledgement\n", j);
			printf("-----------------------------------------------------\n");
			strcpy(write_buff, msg1);
			write_buff[strlen(msg1)] = j + '0';
			write(cli_sock, write_buff, sizeof(write_buff));
	        }
	}
	close(cli_sock);
}