ddd

#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/errno.h>
#include "stdafx.h"

const unsigned short int PORT = 1234;
char buffer[255];

int sendall(int fd, const char *data, int *len)
{
	int transfered = 0; // Bytes already sent
	int left = *len; // Bytes still to send
	int i;

	while (transfered < *len)
	{
		i = send(fd, data + transfered, left, 0);
		if (i == -1)
		{
			break;
		}; // Error!
		transfered += i;
		left -= i;
	};

	*len = transfered;
	return i == -1 ? -1 : 0;
}
int main(void)
{
	int fd, connectionfd;
	struct sockaddr_in ownAddress;
	struct sockaddr_in remAddress;
	int addrlen;
	char str[INET_ADDRSTRLEN];

	//create a socket:
	if ((fd = socket(PF_INET, SOCK_STREAM, 0)) == -1)
	{
		perror("socket");
		exit(1);
	}

	//IP address and port number of the server:
	ownAddress.sin_family = AF_INET;  //AF_INET= IPv4
	ownAddress.sin_port = htons(PORT);  //htons=change Host byte order TO Network byte order, Short data
	ownAddress.sin_addr.s_addr = INADDR_ANY;  //INADDR_ANY=listen on each
											  //available network interface;
											  //can also listen on a specific address
	memset(&(ownAddress.sin_zero), '\0', 8);

	//bind to the address and port:
	if (bind(fd, (struct sockaddr *) &ownAddress, sizeof(struct sockaddr)) == -1)
	{
		perror("bind");
		exit(2);
	}

	//listen (wait) for incoming connections from clients:
	if (listen(fd, 5) == -1)  //5=backlog (waiting queue length), usually between 5 and 10
	{
		perror("listen");
		exit(3);
	}

	puts("Waiting for incoming connections...");

	//accept the incoming connection, ie. establish communication with a client:
	addrlen = sizeof(struct sockaddr_in);
	if ((connectionfd = accept(fd, (struct sockaddr *)&remAddress, &addrlen)) == -1)
	{
		perror("accept");
		exit(4);
	}

	//now we have a working connection between this server and some client;
	//we can receive and send data

	//we can also check the address of the connected client:
	inet_ntop(AF_INET, &(remAddress.sin_addr), str, INET_ADDRSTRLEN);
	//(ntop=Network byte order TO (textual) Presentation);
	//a similar function, inet_ntoa(remAddress.sin_addr), is now deprecated
	printf("Connection from: %s\n", str);


	char *message = "Hello";
	int messlen;
	messlen = strlen(message);
	if (sendall(connectionfd, message, &messlen) == -1)
	{
		fprintf(stderr, "Only %d bytes was transferred because of an error!\n", messlen);
	}
	else
	{
		printf("Transfer completed successfully!");
	}


	while (recv(connectionfd, buffer, sizeof(buffer), 0) != -1)
	{
		size_t size = recv(connectionfd, buffer, sizeof(buffer), 0);
		printf(buffer);

		messlen = strlen(buffer);
		if (sendall(connectionfd, buffer, &messlen) == -1)
		{
			fprintf(stderr, "Only %d bytes was transferred because of an error!\n", messlen);
		}
		else
		{
			printf("Transfer completed successfully!");
		}

		*buffer = NULL;
		close(connectionfd); //close connection when finished with this client
	}

	close(fd);  //close server's socket when all server work is finished
	return 0;
}