How to Listen to HTTPS and HTTP on the Same Port Depending on Host with GO?

Welcome to this informative article, where we’ll dive into the world of GO programming and explore how to listen to both HTTPS and HTTP requests on the same port, depending on the host. This might seem like a complex task, but fear not, dear reader, as we’ll break it down into manageable chunks, making it easy for you to follow along.

Why Do We Need to Listen to Both HTTPS and HTTP?

In today’s digital landscape, securing online communications is of utmost importance. HTTPS (Hypertext Transfer Protocol Secure) provides an additional layer of security by encrypting data in transit. However, there might be scenarios where you need to support both HTTPS and HTTP connections, such as:

• Legacy system integration: You might need to support older systems that don’t support HTTPS.
• Development and testing: You might want to test your application using HTTP for simplicity and then switch to HTTPS for production.
• Load balancing: You might need to distribute traffic between HTTPS and HTTP servers.

The GO Programming Language

GO, also known as Golang, is a statically typed, compiled, and designed to be concurrent and garbage-collected programming language developed by Google. It’s an excellent choice for building scalable and concurrent systems, making it a popular choice for web development.

The Challenge: Listening to Both HTTPS and HTTP on the Same Port

The main challenge lies in configuring your GO application to listen to both HTTPS and HTTP requests on the same port. By default, the GO `net/http` package doesn’t allow you to listen to both protocols on the same port. But fear not, we’ll show you how to overcome this limitation.

The Solution: Using a Reverse Proxy

One way to listen to both HTTPS and HTTP requests on the same port is by using a reverse proxy. A reverse proxy is a server that sits between the client and the origin server, forwarding requests and responses between them. We’ll use the GO `net/http` package to create a reverse proxy that listens to both HTTPS and HTTP requests.

Step 1: Create a GO Project

Create a new GO project and add the following code to your `main.go` file:

package main

import (
	"fmt"
	"net/http"
)

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprint(w, "Hello, World!")
	})

	http.ListenAndServe(":8080", nil)
}

This code sets up an HTTP server that listens on port 8080 and responds with “Hello, World!” to any request.

Step 2: Create a Reverse Proxy

To create a reverse proxy, we’ll use the `net/http/httputil` package. Add the following code to your `main.go` file:

package main

import (
	"fmt"
	"net/http"
	"net/http/httputil"
)

func main() {
	proxy := httputil.NewSingleHostReverseProxy(&url.URL{
		Scheme: "https",
		Host:   "example.com:443",
	})

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		proxy.ServeHTTP(w, r)
	})

	http.ListenAndServe(":8080", nil)
}

This code creates a reverse proxy that forwards requests to `https://example.com:443`. We’ll modify this code to listen to both HTTPS and HTTP requests.

Step 3: Configure the Reverse Proxy to Listen to Both HTTPS and HTTP

To listen to both HTTPS and HTTP requests, we’ll modify the reverse proxy to inspect the `Host` header of the incoming request and forward it to the appropriate server. Add the following code to your `main.go` file:

package main

import (
	"fmt"
	"net/http"
	"net/http/httputil"
)

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		var target *url.URL
		if r.Host == "example.com:443" {
			target = &url.URL{
				Scheme: "https",
				Host:   "example.com:443",
			}
		} else {
			target = &url.URL{
				Scheme: "http",
				Host:   "example.com:80",
			}
		}

		proxy := httputil.NewSingleHostReverseProxy(target)
		proxy.ServeHTTP(w, r)
	})

	http.ListenAndServe(":8080", nil)
}

This code inspects the `Host` header of the incoming request and forwards it to either the HTTPS or HTTP server depending on the host.

SSL/TLS Certificates

To enable HTTPS, you’ll need to obtain an SSL/TLS certificate for your domain. You can obtain a free SSL/TLS certificate from Let’s Encrypt or purchase one from a trusted certificate authority.

Step 4: Configure SSL/TLS Certificates

Once you have obtained your SSL/TLS certificate, you’ll need to configure it in your GO application. Add the following code to your `main.go` file:

package main

import (
	"fmt"
	"net/http"
	"net/http/httputil"
	"log"
	"crypto/tls"
)

func main() {
	cert, err := tls.LoadX509KeyPair("cert.pem", "key.pem")
	if err != nil {
		log.Fatal(err)
	}

	config := &tls.Config{
		Certificates: []tls.Certificate{cert},
	}

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		var target *url.URL
		if r.Host == "example.com:443" {
			target = &url.URL{
				Scheme: "https",
				Host:   "example.com:443",
			}
		} else {
			target = &url.URL{
				Scheme: "http",
				Host:   "example.com:80",
			}
		}

		proxy := httputil.NewSingleHostReverseProxy(target)
		proxy.ServeHTTP(w, r)
	})

	server := &http.Server{
		Addr:      ":8080",
		TLSConfig: config,
	}

	log.Println("Listening on :8080...")
	server.ListenAndServeTLS("cert.pem", "key.pem")
}

This code loads the SSL/TLS certificate and configures the GO application to use it for HTTPS requests.

Conclusion

In this article, we’ve demonstrated how to listen to both HTTPS and HTTP requests on the same port using a reverse proxy in GO. By following these steps, you can configure your GO application to support both protocols, depending on the host. Remember to obtain an SSL/TLS certificate and configure it in your application to enable HTTPS.

Keyword	Description
GO	GO programming language
HTTPS	Hypertext Transfer Protocol Secure
HTTP	Hypertext Transfer Protocol
Reverse Proxy	A server that sits between the client and the origin server
SSL/TLS Certificate	A digital certificate that enables HTTPS

We hope this article has been informative and helpful in guiding you through the process of listening to both HTTPS and HTTP requests on the same port using a reverse proxy in GO. Happy coding!

1. GO Programming Language
2. Let’s Encrypt
3. SSL/TLS Certificates

Frequently Asked Question

Confused about how to listen to HTTPS and HTTP on the same port depending on the host with GO? Let’s break it down with these 5 FAQs!