#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h>

#include "proxy.h"

static int parse_host(const char *host, const char *port, struct addrinfo **addr)
{
	struct addrinfo hints = {
		.ai_family   = AF_UNSPEC,
		.ai_socktype = SOCK_STREAM,
		.ai_flags    = AI_PASSIVE,
	};

	int err;
	if ((err = getaddrinfo(host, port, &hints, addr))) {
		fprintf(stderr, "getaddrinfo failed: %s\n", gai_strerror(err));
		return -1;
	}

	return 0;
}

static int listen_source(struct addrinfo *source)
{
	int fd = -1;
	for (struct addrinfo *a = source; a; a = a->ai_next) {
		if ((fd = socket(a->ai_family, a->ai_socktype, a->ai_protocol)) == -1)
			continue;
		if (!bind(fd, a->ai_addr, a->ai_addrlen) && !listen(fd, 1))
			break;
		close(fd);
		fd = -1;
	}
	return fd;
}

static int connect_target(struct addrinfo *target)
{
	int fd = -1;
	for (struct addrinfo *a = target; a; a = a->ai_next) {
		if ((fd = socket(a->ai_family, a->ai_socktype, a->ai_protocol)) == -1)
			continue;
		if (connect(fd, a->ai_addr, a->ai_addrlen) != -1)
			break;
		close(fd);
		fd = -1;
	}
	return fd;
}

int main(int argc, char **argv)
{
	struct addrinfo *source;
	struct addrinfo *target;

	if (argc != 3) {
		fprintf(stderr, "usage: %s targethost targetport\n", argv[0]);
		return -1;
	}

	if (parse_host(NULL, "1234", &source))
		return -1;
	if (parse_host(argv[1], argv[2], &target))
		return -1;

	int listenfd = listen_source(source);
	if (listenfd < 0) {
		perror("listen_source");
		return -1;
	}

	for (;;) {
		int sourcefd = accept(listenfd, NULL, NULL);
		if (sourcefd == -1) break;

		int targetfd = connect_target(target);
		if (targetfd == -1) {
			perror("connect_target");
			close(sourcefd);
			break;
		}

		proxy(sourcefd, targetfd, 500);

		close(targetfd);
		close(sourcefd);
	}

	close(listenfd);
	return 0;
}