TLS-Client

Preface

This TLS Client is built upon https://github.com/Carcraftz/fhttp and https://github.com/Carcraftz/utls (https://github.com/refraction-networking/utls). Big thanks to all contributors so far. Sadly it seems that the original repositories from Carcraftz are not maintained anymore.

What is TLS Fingerprinting?

Some people think it is enough to change the user-agent header of a request to let the server think that the client requesting a resource is a specific browser. Nowadays this is not enough, because the server might use a technique to detect the client browser which is called TLS Fingerprinting.

Even though this article is about TLS Fingerprinting in NodeJS it well describes the technique in general. https://httptoolkit.tech/blog/tls-fingerprinting-node-js/#how-does-tls-fingerprinting-work

Why is this library needed?

With this library you are able to create a http client implementing an interface which is similar to golangs net/http client interface. This TLS Client allows you to specify the Client (Browser and Version) you want to use, when requesting a server.

The Interface of the HTTP Client looks like the following and extends the base net/http Client Interface by some useful functions. Most likely you will use the Do() function like you did before with net/http Client.

type HttpClient interface {
    GetCookies(u *url.URL) []*http.Cookie
    SetCookies(u *url.URL, cookies []*http.Cookie)
    SetCookieJar(jar http.CookieJar)
    GetCookieJar() http.CookieJar
    SetProxy(proxyUrl string) error
    GetProxy() string
    SetFollowRedirect(followRedirect bool)
    GetFollowRedirect() bool
    CloseIdleConnections()
    Do(req *http.Request) (*http.Response, error)
    Get(url string) (resp *http.Response, err error)
    Head(url string) (resp *http.Response, err error)
    Post(url, contentType string, body io.Reader) (resp *http.Response, err error)
}

Quick Usage Example

package main

import (
	"fmt"
	"io"
	"log"

	http "github.com/bogdanfinn/fhttp"
	tls_client "github.com/bogdanfinn/tls-client"
	"github.com/bogdanfinn/tls-client/profiles"
)

func main() {
    jar := tls_client.NewCookieJar()
	options := []tls_client.HttpClientOption{
		tls_client.WithTimeoutSeconds(30),
		tls_client.WithClientProfile(profiles.Chrome_120),
		tls_client.WithNotFollowRedirects(),
		tls_client.WithCookieJar(jar), // create cookieJar instance and pass it as argument
	}

	client, err := tls_client.NewHttpClient(tls_client.NewNoopLogger(), options...)
	if err != nil {
		log.Println(err)
		return
	}

	req, err := http.NewRequest(http.MethodGet, "https://tls.peet.ws/api/all", nil)
	if err != nil {
		log.Println(err)
		return
	}

	req.Header = http.Header{
		"accept":                    {"*/*"},
		"accept-language":           {"de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7"},
		"user-agent":                {"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36"},
		http.HeaderOrderKey: {
			"accept",
			"accept-language",
			"user-agent",
		},
	}

	resp, err := client.Do(req)
	if err != nil {
		log.Println(err)
		return
	}

	defer resp.Body.Close()

	log.Println(fmt.Sprintf("status code: %d", resp.StatusCode))

	readBytes, err := io.ReadAll(resp.Body)
	if err != nil {
		log.Println(err)
		return
	}

	log.Println(string(readBytes))
}