server.c

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

#define MAXPENDING 5    /* Max connection requests */
#define BUFFSIZE 32

void Die(char *mess)
{
	perror(mess);
	exit(1);
}

void HandleClient(int sock)
{
	char buffer[BUFFSIZE] = {0};
	int received = -1;
	/* Receive message */
	if ((received = recv(sock, buffer, BUFFSIZE, 0)) < 0)
	{
		Die("Failed to receive initial bytes from client");
	}
	
	fprintf(stdout, "server recv content: %s\n", buffer);
	
	/* Send bytes and check for more incoming data in loop */
	while (received > 0)
	{
		/* Send back received data */
		if (send(sock, buffer, received, 0) != received)
		{
        		Die("Failed to send bytes to client");
     		}
		
		/* Check for more data */
		if ((received = recv(sock, buffer, BUFFSIZE, 0)) < 0)
		{
			Die("Failed to receive additional bytes from client");
		}
		
		fprintf(stdout, "server received length: %d\n", received);
	}
	
	close(sock);
}

int main(int argc, char *argv[])
{
	int serversock = 0;
	int clientsock = 0;
	struct sockaddr_in echoserver;
	struct sockaddr_in echoclient;

	if (argc != 2)
	{
		fprintf(stderr, "USAGE: echoserver <port>\n");
		exit(1);
	}
	
	/* Create the TCP socket */
	if ((serversock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
	{
		Die("Failed to create socket");
	}

	/* Construct the server sockaddr_in structure */
	memset(&echoserver, 0, sizeof(echoserver));       /* Clear struct */
	echoserver.sin_family = AF_INET;                  /* Internet/IP */
	echoserver.sin_addr.s_addr = htonl(INADDR_ANY);   /* Incoming addr */
	echoserver.sin_port = htons(atoi(argv[1]));       /* server port */

	/* Bind the server socket */
	if (bind(serversock, (struct sockaddr *)&echoserver, sizeof(echoserver)) < 0)
	{
		Die("Failed to bind the server socket");
	}
	
	/* Listen on the server socket */
	if (listen(serversock, MAXPENDING) < 0)
	{
		Die("Failed to listen on server socket");
	}
	
	/* Run until cancelled */
	while (1)
	{
		unsigned int clientlen = sizeof(echoclient);
		/* Wait for client connection */
		if ((clientsock = accept(serversock, (struct sockaddr *)&echoclient, &clientlen)) < 0)
		{
			Die("Failed to accept client connection");
		}
		
		fprintf(stdout, "Client connected: %s\n", inet_ntoa(echoclient.sin_addr));
		HandleClient(clientsock);
	}
}