// The Go Failing TCP Connection Challenge!
//
// Print the source IP address and port number of an outgoing TCP connection
// that times out and doesn't connect to the remote host.
//
// Rules:
//
// 1. You can't set the local address or port number.  The local address must
//    be 0.0.0.0 (INADDR_ANY), and the port number must be 0 (so the kernel
//    selects an ephemeral port).
//
// 2. You can't use the "unsafe" package.
//
// 3. Whatever you do needs to return a net.Conn.
package main

import (
	"fmt"
	"net"
	"time"
)

func main() {
	if conn, err := net.DialTimeout("tcp4", "google.com:7357", time.Second); err != nil {
		fmt.Printf("Connection timed out:\n%#v\n%q\n", err, err)
		// &net.OpError{Op:"dial", Net:"tcp4", Source:net.Addr(nil), Addr:(*net.TCPAddr)(0xc000112630), Err:(*net.timeoutError)(0x1209ce0)}
		// "dial tcp4 172.217.10.46:7357: i/o timeout" <-- shows destination but not source
	} else {
		fmt.Printf("Connection succeeded:\n%#v\n%v -> %v\n", conn, conn.LocalAddr(), conn.RemoteAddr())
	}
}

#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

int main() {
	struct addrinfo hints;
	memset(&hints, 0, sizeof hints);
	hints.ai_family = AF_INET;
	hints.ai_socktype = SOCK_STREAM;

	struct addrinfo *results;
	getaddrinfo("google.com", "7357", &hints, &results);

	int fd;
	struct addrinfo *r = results;

	fd = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
	fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, NULL) | O_NONBLOCK);
	connect(fd, r->ai_addr, r->ai_addrlen);

	struct sockaddr_in sal;
	socklen_t sal_len = sizeof sal;
	getsockname(fd, (struct sockaddr *)&sal, &sal_len);

	char la[256], ra[256];
	strlcpy(la, inet_ntoa(sal.sin_addr), 256);
	strlcpy(ra, inet_ntoa(((struct sockaddr_in *)(r->ai_addr))->sin_addr), 256);

	printf(
	  "%s:%u -> %s:%u\n",
	  la, ntohs(sal.sin_port),
	  ra, ntohs(((struct sockaddr_in *)(r->ai_addr))->sin_port)
	);
	return 0;
}