server_fork.c

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

void sigchld_handler(int signo)
{
	while(waitpid(-1, NULL, WHOHANG) > 0);
}

int main() {

	int def_sock, new_sock;
	struct sockaddr_in s_addr;
	struct sockaddr_in n_addr;
	socklen_t addr_size;
	char buffer[1024];
	int result;
	int nread;
	pid_t pid;

	/*---- Create the socket. The three arguments are: ----*/
	/* 1) Internet domain 2) Stream socket 3) Default protocol (TCP in this case) */
	def_sock = socket(AF_INET, SOCK_STREAM, 0);

	if  (def_sock == -1) {
		printf("Socket can't be created, exit script");
		exit(1);
	}


	/*---- Configure settings of the server address struct ----*/
	s_addr.sin_family = AF_INET;
	s_addr.sin_port = htons(5001);
	s_addr.sin_addr.s_addr = INADDR_ANY;

	memset(s_addr.sin_zero, '0', sizeof s_addr.sin_zero);
	printf("Port = '%d'\n", s_addr.sin_port);

	/*---- Bind the address struct to the socket ----*/
	result = bind(def_sock, (struct sockaddr *) &s_addr, sizeof(s_addr));
	if (result < 0) {
		printf("Can't bind socket, exiting\n");
		exit(1);
	}



	/*---- Listen on the socket, with 5 max connection requests queued ----*/
	if (listen(def_sock, 5) == 0) {
		printf("Listening\n");
	}
	else {
		printf("Listening can't be started\n");
		exit(1);
	}

	signal(SIGCHLD, sigchld_handler);


	/*---- Accept call creates a new socket for the incoming connection ----*/
	printf("Original pid = '%i'\n", getpid());

	while (1) {
		printf("Test1\n");
		printf("Test3\n");
		addr_size = sizeof n_addr;
		if ((new_sock = accept(def_sock, (struct sockaddr *) &n_addr, &addr_size)) < 0) {
			printf("Hello!\n");
		}
		else {
			printf("Hello2!\n");
		}
		printf("Test4\n");

		if ( new_sock == -1 ) {
			printf("Can't create socket for connection\n");
			exit(1);
		}
		printf("Test2\n");

		pid = fork();
		printf("Fork returned %d\n", (int) pid);

		if ((pid = fork()) == 0) {
			printf("Test1\n");
			printf("Child process %i created\n", getpid());
			close(def_sock);

			nread = recv(new_sock, buffer, 25, 0);
			printf("Test1\n");
			buffer[nread] = '\0';
			printf("%s\n", buffer);
			send(new_sock, buffer, nread, 0);
			close(new_sock);
			sleep(5);
			printf("child process %i finished\n", getpid());
			exit(0);
		}
		printf("Test2\n");
		wait(NULL);

		close(new_sock);

		/*---- Send message to the socket of the incoming connection ----*/
		//memset(buffer, 0, sizeof buffer);
		//strcpy(buffer,"Hello World!\n");
		//send(new_sock,buffer,13,0);

		////*---- Read the message from the client into the buffer ----*/
		////memset(buffer, 0, sizeof buffer);
		//if (recv(new_sock, buffer, sizeof(buffer), 0) < 0) {
			//printf("Can't get message from client\n");
		//}
		//else {
			//printf("Client said %s\n", buffer);
		//}


	}

	return 0;
}