How does headless_chrome (Rust) handle redirects?

headless_chrome, a Rust crate, is a high-level API over the Chrome DevTools Protocol, typically used for web scraping, automated testing, and headless browser requirements. It allows you to control a real Chrome browser, but without the overhead of a GUI. When dealing with web pages, handling redirects is an important aspect.

In headless_chrome, redirects are generally handled automatically by the underlying Chrome instance, just as they would be in a normal browser session. When you navigate to a URL that responds with a redirect (e.g., HTTP status codes 301, 302, 307, etc.), the browser follows the redirect to the new location transparently.

When you are using headless_chrome to interact with web pages, if you want to track redirects or check the final URL after redirects, you will need to monitor the navigation events or check the browser/tab state after the navigation command.

Here is a basic example of how you might use headless_chrome in Rust to navigate to a URL and print out the final URL after any redirects. Note that this example assumes you have already added headless_chrome as a dependency in your Cargo.toml file:

use headless_chrome::{Browser, protocol::page::methods::Navigate};

fn main() -> Result<(), failure::Error> {
    // Launch a new browser instance
    let browser = Browser::default()?;

    // Create a new tab
    let tab = browser.wait_for_initial_tab()?;

    // Navigate to a URL
    let nav_response = tab.navigate_to("http://example.com")?;

    // Wait for the network to be idle (no more requests for half a second)
    tab.wait_until_navigated()?;

    // After navigation, the browser may have been redirected.
    // Retrieve the final URL
    let final_url = tab.get_url();

    println!("Final URL after redirects: {}", final_url);

    Ok(())
}

In this example:

• We create a new browser instance.
• We open a new tab.
• We navigate to the specified URL.
• We wait for the navigation to complete.
• We retrieve the final URL from the tab.

The navigate_to method will initiate the navigation, and if the server responds with a redirect, Chrome will automatically follow it. The wait_until_navigated call will wait for the navigation to complete, which includes following any redirects.

Since headless_chrome is a wrapper around Chrome's DevTools Protocol, you have access to detailed events about the navigation process if you need them. For instance, you could listen to Network.requestWillBeSent events to see all network requests, including redirects.

Keep in mind that the above code is a simple example and doesn't include error handling, nor does it deal with more complex situations like JavaScript-triggered redirects, which may require listening for different events or even evaluating JavaScript code in the page context to determine the final URL.