selective_server.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <fcntl.h>
void rsendd(int ch, int c_sock)
 {
	char buff2[60];
	bzero(buff2, sizeof(buff2));
	strcpy(buff2, "Retransmission message: ");
	buff2[strlen(buff2)] = (ch) + '0';
	buff2[strlen(buff2)] = '\0';
	printf("Resending Message to client: %s \n", buff2);
	write(c_sock, buff2, sizeof(buff2));
	usleep(1000);
}
int main() 
{
	int s_sock, c_sock;
	s_sock = socket(AF_INET, SOCK_STREAM, 0);
	struct sockaddr_in server, other;
	memset(&server, 0, sizeof(server));
	memset(&other, 0, sizeof(other));
	server.sin_family = AF_INET;
	server.sin_port = htons(7004);
	server.sin_addr.s_addr = INADDR_ANY;
	socklen_t add;
	if (bind(s_sock, (struct sockaddr *)&server, sizeof(server)) == -1) {
	printf("Binding failed\n");
	return 0;
	}
	printf("\nSelective repeat - Server\n\n");
	printf("Total frames to be send:9\n");
	printf("Window Size:3\n");
	listen(s_sock, 10);
	add = sizeof(other);
	c_sock = accept(s_sock, (struct sockaddr *)&other, &add);
	time_t t1, t2;
	char msg[50] = "Server message: ";
	char buff[50];
	int flag = 0;
	fd_set set1, set2, set3;
	struct timeval timeout1, timeout2, timeout3;
	int rv1, rv2, rv3;
	int tot = 0;
	int ok[20];
	memset(ok, 0, sizeof(ok));
	while (tot < 9)
	{
		int toti = tot;
		for (int j = (0 + toti); j < (3 + toti); j++) 
		{
			bzero(buff, sizeof(buff));
			char buff2[60];
			bzero(buff2, sizeof(buff2));
			strcpy(buff2, "Server message: ");
			buff2[strlen(buff2)] = (j) + '0';
			buff2[strlen(buff2)] = '\0';
			printf("Message sent to client: %s \n", buff2);
			write(c_sock, buff2, sizeof(buff2));
			usleep(1000);
		}
		for (int k = 0 + toti; k < (toti + 3); k++)
		 {
			qq:
			FD_ZERO(&set1);
			FD_SET(c_sock, &set1);
			timeout1.tv_sec = 2;
			timeout1.tv_usec = 0;
			rv1 = select(c_sock + 1, &set1, NULL, NULL, &timeout1);
			if (rv1 == -1)
			perror("select error");
			else if (rv1 == 0) 
			{
			printf("Timeout for message: %d \n", k);
			rsendd(k, c_sock);
			goto qq;
			}
			else 
			{
			  read(c_sock, buff, sizeof(buff));
			   printf("Message from Client: %s\n", buff);
			   if (buff[0] == 'n') 
			   {
			      printf("Corrupted message acknowledgement (msg %d) \n",buff[strlen(buff) -1]-'0');
			      rsendd((buff[strlen(buff) - 1] - '0'), c_sock);
			      goto qq;
			    }
			    else
			      tot++;
			}
		}
	}
	close(c_sock);
	close(s_sock);
	return 0;
	}