[🐛 Bug]: "Invalid Host Header" in Firefox 106 w/ geckodriver 0.32.0

What happened?

I’m using Firefox 106 with selenium-firefox-driver:4.5.0 for Java and geckodriver 0.32.0 (via Selenide 6.9.0)

Selenium GeckoDriverService launches geckodriver and when starting a new browser session it calls PUT http://localhost:<port>/session

However, since the --allow-hosts localhost flag is not provided when starting geckodriver, requests to geckodriver always return 500 Invalid Host Header

Source of geckodriver arguments:

https://github.com/SeleniumHQ/selenium/blob/7fdaf217b8e58033b7cd01d916e3063c8198a403/java/src/org/openqa/selenium/firefox/GeckoDriverService.java#L187-L211

Source of target url for reqeusts to geckodriver:

https://github.com/SeleniumHQ/selenium/blob/7fdaf217b8e58033b7cd01d916e3063c8198a403/java/src/org/openqa/selenium/remote/service/DriverService.java#L172-L174

---

My suggestion would be to update GeckoDriverService to either include --allow-hosts localhost or override ::getPort(int) to http://127.0.0.1:%d.

How can we reproduce the issue?

Breaks 100% of the time with the specified versions:

import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.firefox.FirefoxOptions;

public class Main {
    public static void main(String[] args) throws Exception {
        var options = new FirefoxOptions();
        System.setProperty("webdriver.gecko.driver", "/usr/bin/geckodriver"); // geckodriver 0.32.0
        options.setBinary("/usr/bin/firefox"); // firefox 106 installed

        var driver = new FirefoxDriver(options);
        driver.get("https://www.stackoverflow.com");
    }
}

Relevant log output

1668526366108	geckodriver	INFO	Listening on 127.0.0.1:55726
1668526366212	webdriver::server	WARN	Rejected request with Host header localhost:55726, allowed values are []
Exception in thread "main" org.openqa.selenium.SessionNotCreatedException: Could not start a new session. Response code 500. Message: Invalid Host header localhost:55726

Operating System

linux

Selenium version

java 4.5.0

What are the browser(s) and version(s) where you see this issue?

Firefox 106

What are the browser driver(s) and version(s) where you see this issue?

geckodriver 0.32.0

[titusfortner]

Well, you should be able to create your own GeckoDriverService with the arguments specified, but I haven’t tested it to see if they get overridden somewhere (FirefoxService code is a bit weird for legacy reasons). The code itself encourages using the Builder, though, and that doesn’t support adding arguments. I want us to do a review of it all soon.

[zireael-0]

@diemol To be honest, I don’t think this is a misconfig. Yes, I was able to work around the issue by updating my system configuration. However, if you ask me, having an empty /etc/hosts file is not a misconfiguration - it’s even the default on my distro.

I don’t know if it’s necessary to change this within selenium per-se. But in my opinion there should at least be a way to pass additional parameters to geckodriver for cases like this. Right now, I can set parameters to launch firefox via FirefoxOptions, but not geckodrvier itself.

If I had no su access to the machine I am working on, I wouldn’t have been able to resolve this.