#define _POSIX_SOURCE

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

#define MAXSIZE 1024

/*
 * client.c: Implementation of a very simple tcp client.
 */
int main(int argc, char *argv[])
{
	struct addrinfo hints;	/* specify our needs */
	struct addrinfo *res;	/* resulting address structure */
	struct addrinfo *r;	/* iterator */
	int err;		/* status of getaddrinfo() */
	int s;			/* socket  */
	char c1;		/* compared to 'y' */
	char c2;		/* compared to '\n' */
	char line[MAXSIZE];	/* message buffer */

	/* Enforce correct usage */
	if (argc != 3)
	{
		printf("Usage: %s [server] [port]\n", argv[0]);
		exit(EXIT_FAILURE);
	}

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_INET;		/* IPv4 */
	hints.ai_socktype = SOCK_STREAM;	/* Stream socket */
	hints.ai_protocol = 0;			/* Any (TCP) */

	/*
		$ man getaddrinfo
		[...]
		Given node and service, which identify an Internet host and a
		service, getaddrinfo() returns one or more addrinfo structures,
		each of which contains an Internet address that can be specified
		in a call to bind(2) or connect(2).
		[...]
	*/
	err = getaddrinfo(argv[1], argv[2], &hints, &res);
	if (err != 0)
	{
		fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(err));
		exit(EXIT_FAILURE);
	}

	/* Loop through the address structures */
	for (r = res; r != NULL; r = r->ai_next)
	{
		/* Create the socket */
		s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
		if (s < 0)
		{
			perror("socket");
			continue;
		}

		/* Connect to the server */
		if (connect(s, res->ai_addr, res->ai_addrlen) < 0)
		{
			close(s);
			perror("connect");
			continue;
		}

		/* Success */
		break;
	}

	/* Give up */
	if (r == NULL)
	{
		fprintf(stderr, "Connecting failed!\n");
		exit(EXIT_FAILURE);
	}

	/* No longer needed */
	freeaddrinfo(res);

	printf("Connection established...\n");
	printf("-------------------------\n");

	/* Infinitely offering to send more */
	for (;;)
	{
		printf("\nType 'y' to send one (more) message: ");

		c1 = getchar();
		c2 = getchar();

		if ((c1 == 'y') && (c2 == '\n'))
		{
			/* Clear message buffer */
			memset(line, 0, sizeof(line));

			/*
				$ man fgets
				[...]
				gets() and fgets() return s on success, and NULL
				on error or when end of file occurs while no
				characters have been read.
				[...]
			*/
			if (fgets(line, sizeof(line), stdin))
			{
				/* Finally: Send user's message to server */
				if (send(s, line, sizeof(line), 0) < 0)
				{
					perror("send");
					exit(EXIT_FAILURE);
				}
			}
		}
		else
		{
			break;
		}
	}

	printf("\n-----\n");
	printf("Exit!\n");

	/* Clean up */
	shutdown(s, 2);
	close(s);

	return EXIT_SUCCESS;
}