#include <iostream>
#include <cstdlib>

#include <strings.h>	//for bzero
#include <netdb.h>	//for getservbyname, h_errno
#include <sys/socket.h>	//for socket
#include <arpa/inet.h>  //for inet_ntop
using namespace std;

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

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

	//Change the string "localhost" to an IP address.
	struct hostent *entry = gethostbyname("localhost");
	if (entry == 0) {
		cerr << argv[0] << ": gethostbyname, h_errno == " << h_errno
			<< "\n";
		return 2;
	}
	address.sin_addr.s_addr =
		*reinterpret_cast<in_addr_t *>(entry->h_addr_list[0]);

	//Print the IP address as a string of numbers with dots.
	char buffer[INET_ADDRSTRLEN];
	if (inet_ntop(AF_INET, &address.sin_addr, buffer, sizeof buffer) == 0) {
		perror(argv[0]);
		return 3;
	}
	cout << "Trying " << buffer << "...\n";

	//Try to connect to the echo server.
	if (connect(s, reinterpret_cast<const struct sockaddr *>(&address),
		sizeof address) != 0) {
		perror(argv[0]);
		return 4;
	}

	//Print the hostname corresponding to the IP address.
	entry = gethostbyaddr(reinterpret_cast<const char *>(&address.sin_addr),
		sizeof address.sin_addr, AF_INET);
	if (entry == NULL) {
		cerr << argv[0] << ": gethostbyaddr, h_errno == " << h_errno
			<< "\n";
		return 5;
	}
	cout << "Connected to " << entry->h_name << ".\n";

	//Send one byte to the echo server.
	char c = 'A';
	if (write(s, &c, 1) != 1) {
		perror(argv[0]);
		return 6;
	}

	//Get one byte from the echo server.
	c = '\0';	//Prove that there's nothing up my sleve.
	if (read(s, &c, 1) != 1) {
		perror(argv[0]);
		return 7;
	}
	cout << c << "\n";

	if (shutdown(s, SHUT_RDWR) != 0) {
		perror(argv[0]);
		return 8;
	}

	return EXIT_SUCCESS;
}