socket_client

//============================================================================
// Name        : socket_demo.cpp
// Author      : aGuegu
// Version     :
// Copyright   : GPL v2.0
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

void error(const char *msg) {
	perror(msg);
	exit(0);
}

int main(int argc, char *argv[]) {
	if (argc < 3) {
		fprintf(stderr, "usage %s hostname port\n", argv[0]);
		exit(0);
	}
	int port_number = atoi(argv[2]);

	int socket_fd = socket(AF_INET, SOCK_STREAM, 0);
	if (socket_fd < 0)
		error("ERROR opening socket");

	struct hostent * server = gethostbyname(argv[1]);
	if (server == NULL) {
		fprintf(stderr, "ERROR, no such host\n");
		exit(0);
	}

	struct sockaddr_in server_address;
	bzero((char *) &server_address, sizeof(server_address));
	server_address.sin_family = AF_INET;
	bcopy((char *) server->h_addr, (char *)&server_address.sin_addr.s_addr, server->h_length);

	server_address.sin_port = htons(port_number);

	if (connect(socket_fd, (struct sockaddr *) &server_address, sizeof(server_address)) < 0)
		error("ERROR connecting");

	printf("Please enter the message: ");

	char buffer[256];
	bzero(buffer, 256);
	fgets(buffer, 255, stdin);

	int n = write(socket_fd, buffer, strlen(buffer));
	if (n < 0)
		error("ERROR writing to socket");

	bzero(buffer, 256);

	n = read(socket_fd, buffer, 255);
	if (n < 0)
		error("ERROR reading from socket");

	printf("%s\n", buffer);
	close(socket_fd);
	return EXIT_SUCCESS;
}

socket_server

//============================================================================
// Name        : socket_server_demo.cpp
// Author      : aGuegu
// Version     :
// Copyright   : GPL v2.0
// Description : Hello World in C++, Ansi-style
//============================================================================

/* A simple server in the internet domain using TCP
 The port number is passed as an argument */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

void error(const char *msg) {
	perror(msg);
	exit(1);
}

int main(int argc, char *argv[]) {
	if (argc < 2) {
		fprintf(stderr, "ERROR, no port provided\n");
		exit(1);
	}
	int port_number = atoi(argv[1]);

	int socket_fd = socket(AF_INET, SOCK_STREAM, 0);
	if (socket_fd < 0)
		error("ERROR opening socket");

	struct sockaddr_in server_address;
	bzero((char *) &server_address, sizeof(server_address));

	server_address.sin_family = AF_INET;
	server_address.sin_addr.s_addr = INADDR_ANY;
	server_address.sin_port = htons(port_number);

	if (bind(socket_fd, (struct sockaddr *) &server_address, sizeof(server_address)) < 0)
		error("ERROR on binding");

	listen(socket_fd, 5);

	struct sockaddr_in client_address;
	socklen_t client_length = sizeof(client_address);
	int socket_fd_sub = accept(socket_fd, (struct sockaddr *) &client_address, &client_length);
	if (socket_fd_sub < 0)
		error("ERROR on accept");

	char buffer[256];
	bzero(buffer, 256);
	int n = read(socket_fd_sub, buffer, 255);

	if (n < 0)
		error("ERROR reading from socket");

	printf("Here is the message: %s\n", buffer);
	n = write(socket_fd_sub, "I got your message", 18);
	if (n < 0)
		error("ERROR writing to socket");

	close(socket_fd_sub);
	close(socket_fd);
	return EXIT_SUCCESS;
}