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

#define MYPORT 3490    // the port users will be connecting to

#define BACKLOG 10     // how many pending connections queue will hold

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

int main(void)
{
	int sockfd, new_fd;  // listen on sock_fd, new connection on new_fd
	struct sockaddr_in my_addr;    // my address information
	struct sockaddr_in their_addr; // connector's address information
	socklen_t sin_size;
	struct sigaction sa;
	int yes=1;
	char buf[255];
	socklen_t len=254;
	security_context_t con = NULL;

	if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
		perror("socket");
		exit(1);
	}

	if (setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(int)) == -1) {
		perror("setsockopt");
		exit(1);
	}

	my_addr.sin_family = AF_INET;         // host byte order
	my_addr.sin_port = htons(MYPORT);     // short, network byte order
	my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP
	memset(&(my_addr.sin_zero), '\0', 8); // zero the rest of the struct

	if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr))
			== -1) {
		perror("bind");
		exit(1);
	}

	if (listen(sockfd, BACKLOG) == -1) {
		perror("listen");
		exit(1);
	}

	sa.sa_handler = sigchld_handler; // reap all dead processes
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = SA_RESTART;
	if (sigaction(SIGCHLD, &sa, NULL) == -1) {
		perror("sigaction");
		exit(1);
	}

	while(1) {  // main accept() loop
		sin_size = sizeof(struct sockaddr_in);
		if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr,
						&sin_size)) == -1) {
			perror("accept");
			continue;
		}
// 		if (getsockopt(new_fd, SOL_SOCKET, SO_PEERSEC, con, &len)) {
		if (getpeercon(new_fd, &con)) {
			perror("getsockopt");
		}
		printf("server: got connection from %s, %s\n",
				inet_ntoa(their_addr.sin_addr), con);
		if (!fork()) { // this is the child process
			close(sockfd); // child doesn't need the listener
			sprintf(buf, "Hello, %s", con);
			if (send(new_fd, buf, strlen(buf), 0) == -1)
				perror("send");
			close(new_fd);
			exit(0);
		}
		close(new_fd);  // parent doesn't need this
	}

	return 0;
}