echo_server.c

Socket programming server/client

#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<strings.h>
#include<unistd.h>
#include<arpa/inet.h>


#define ERROR	-1
#define MAX_DATA	1024
int main(int argc, char **argv)
{
	if(argc < 2) {printf("./server port\n"); exit(-1);}
	int sock;
	// create a socket	
	if((sock = socket(AF_INET, SOCK_STREAM, 0)) == ERROR)
	{
		perror("server socket: ");
		exit(-1);
	}

	struct sockaddr_in server;
	bzero(&server, sizeof(server));
	server.sin_family = AF_INET;
	server.sin_port = htons(atoi(argv[1]));
	server.sin_addr.s_addr = INADDR_ANY;
	// bind a socket
	if((bind(sock, (struct sockaddr *)&server, sizeof(server))) == ERROR)
	{
		perror("bind : ");
		exit(-1);
	}

#define MAX_CLIENTS	2
	// listen a socket	
	if((listen(sock, MAX_CLIENTS)) == ERROR)
	{
		perror("listen");
		exit(-1);
	}

	int cli;
	struct sockaddr_in client;
	int sockaddr_len = sizeof(struct sockaddr_in);
	int data_len;
	char data[MAX_DATA];
	while(1) // Better signal handling required
	{
		if((cli = accept(sock, (struct sockaddr *)&client, &sockaddr_len)) == ERROR)
		{
			perror("accept");
			exit(-1);
		}
		printf("New Client connected from port no %d and IP %s\n", ntohs(client.sin_port), inet_ntoa(client.sin_addr));
		do
		{
			printf("wait data from client..\n");
			data_len = read(cli, data, MAX_DATA);
			
			if(data_len > 0)
			{
				data[data_len] = '\0';
				printf("%d bytes is sent: %s", data_len, data);
				write(cli, data, data_len);
			} else {
				perror("read");
			}
			 
		}while(data_len > 0);
		printf("Client disconnected\n");
		close(cli);
	}
	close(sock);
	return 0;
}