TCP Sockets written in C

c_tcp_client_server_threads.c

#include <arpa/inet.h>
#include <netdb.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

#define HOST "localhost"
#define SERVER_PORT 3107

#define STATUS_OK "OK"
#define FLAGS 0

pthread_barrier_t barrier_server_init;

void * tcp_server(void * args) {
	int sock_server = 0, sock_client = 0;
	struct sockaddr_in server, client;
	int c = sizeof(struct sockaddr_in);
	char client_message[1024] = {0};
	int read_size = 0;
	
	printf("SERVER: start \n");
	sock_server = socket(AF_INET , SOCK_STREAM , 0);
	if (sock_server == -1) {
		perror("ERROR socket: ");
		return NULL;
	}
	
	// Prepare the sockaddr_in structure
	server.sin_family = AF_INET;
	server.sin_addr.s_addr = INADDR_ANY;
	server.sin_port = htons(SERVER_PORT);
	
	// Bind
	printf("SERVER: bind \n");
	if(bind(sock_server, (struct sockaddr *)&server , sizeof(server)) < 0) {
		perror("ERROR bind: ");
		return NULL;
	}
	
	printf("SERVER: listen \n");
	if(listen(sock_server , 5) < 0) {
		perror("ERROR listen: ");
		return NULL;
	}
	
	pthread_barrier_wait(&barrier_server_init);
	
	while(1) {
		c = sizeof(struct sockaddr_in);
		sock_client = accept(sock_server, (struct sockaddr *)&client, (socklen_t*)&c);

		bzero(client_message, sizeof(client_message));
		read_size = recv(sock_client, client_message, sizeof(client_message), FLAGS);
		printf("SERVER: Receive message (%d bytes) \"%s\"\n", read_size, client_message);
		sleep(3);
		
		send(sock_client, STATUS_OK, strlen(STATUS_OK), FLAGS);
		
		close(sock_client);
		fflush(stdout);
	}
	
	return NULL;
}

void * tcp_client(void * args) {
	int sock;
	struct hostent * host;
	struct sockaddr_in server;
	char request[1024] , response[1024];
	
	pthread_barrier_wait(&barrier_server_init);
	
	// Create socket
	sock = socket(AF_INET , SOCK_STREAM , 0);
	if (sock == -1) {
		perror("ERROR socket: ");
	}
	
	host = gethostbyname(HOST);	
	memcpy(&server.sin_addr.s_addr, host->h_addr_list[0], sizeof(server.sin_addr.s_addr));
	// server.sin_addr.s_addr = inet_addr("127.0.0.1");
	server.sin_family = AF_INET;
	server.sin_port = htons(SERVER_PORT);

	// Connect to remote server
	if (connect(sock , (struct sockaddr *)&server , sizeof(server)) < 0) {
		perror("ERROR conncect: ");
		return NULL;
	}
	
	snprintf(request, sizeof(request), "Hello from client to server...");
	send(sock , request , strlen(request) , FLAGS);
	recv(sock , response , sizeof(response) , FLAGS);
	printf("CLIENT: Receive message \"%s\"\n", response);
	
	close(sock);

	printf("CLIENT: done \n");
	fflush(stdout);
	return NULL;
}

int main(int argc, char** argv) {
	pthread_t client, server;

	printf("Start...\n");

	pthread_barrier_init(&barrier_server_init, NULL, 2 /* Client and Server */);

	pthread_create(&client, NULL, &tcp_client, NULL);
	pthread_create(&server, NULL, &tcp_server, NULL);

	pthread_join(client, NULL);
	pthread_join(server, NULL);
	
	printf("Done...\n");

	return (EXIT_SUCCESS);
}