#include <iostream>
#include <cstdlib>

#include <strings.h>	//for bzero
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
using namespace std;

int main(int argc, char **argv)
{
	//file descriptor for accepting a client
	const int s = socket(AF_INET, SOCK_STREAM, 0);
	if (s < 0) {
		perror(argv[0]);
		return 1;
	}

	int reuseaddr = 1;
	if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
		&reuseaddr, sizeof reuseaddr) != 0) {
		perror(argv[0]);
		return 2;
	}

	reuseaddr = 0;
	size_t opt_length = sizeof reuseaddr;
	if (getsockopt(s, SOL_SOCKET, SO_REUSEADDR, &reuseaddr, &opt_length)
		!= 0) {
		perror(argv[0]);
		return 3;
	}

	cout << "The SO_REUSEADDR option of the socket is " << reuseaddr
		<< ".\n";

	//In real life, the TCP/IP echo server is always bound to port 7,
	//not port 3000.
	struct sockaddr_in serveraddress;
	bzero(&serveraddress, sizeof serveraddress);
	serveraddress.sin_family = AF_INET;
	serveraddress.sin_port = htons(3000);
	serveraddress.sin_addr.s_addr = INADDR_ANY;

	if (bind(s, reinterpret_cast<struct sockaddr *>(&serveraddress),
		sizeof serveraddress) != 0) {
		perror(argv[0]);
		return 4;
	}

	if (listen(s, SOMAXCONN) != 0) {
		perror(argv[0]);
		return 5;
	}

	struct sockaddr_in clientaddress;
	socklen_t length = sizeof clientaddress;

	//file descriptor for talking to client
	const int client = accept(s,
		reinterpret_cast<struct sockaddr *>(&clientaddress), &length);
	if (client < 0) {
		perror(argv[0]);
		return 6;
	}

	char dotted[INET6_ADDRSTRLEN];
	if (inet_ntop(AF_INET, &clientaddress.sin_addr, dotted, sizeof dotted)
		== NULL) {
		perror(argv[0]);
		return 7;
	}

	cout << "I have accepted a client whose IP address is "
		<< dotted << ".\n";

	//The service provided by this server is to input and output one
	//character.
	char c;
	if (read(client, &c, 1) != 1) {
		perror(argv[0]);
		return 8;
	}

	if (write(client, &c, 1) != 1) {
		perror(argv[0]);
		return 9;
	}

	if (shutdown(client, SHUT_RDWR) != 0) {
		perror(argv[0]);
		return 10;
	}

	return EXIT_SUCCESS;
}