How does Pholcus deal with CAPTCHAs?

Pholcus is a distributed, high-concurrency, and powerful web crawler software written in Go. It's designed for vertical search engines, but it can also be used as a general-purpose web crawler. However, like many other web crawlers, Pholcus itself does not have built-in capabilities to deal with CAPTCHAs, as CAPTCHAs are specifically designed to prevent automated access by bots and scripts, which includes web crawlers.

When you encounter CAPTCHAs while scraping websites using Pholcus or any other web scraping tool, you typically have a few options:

1. Manual Solving: Pause the scraping process and solve the CAPTCHA manually. This is not scalable or efficient for large-scale scraping tasks.

2. CAPTCHA Solving Services: Use third-party CAPTCHA solving services that provide APIs to programmatically send CAPTCHAs and receive the solved responses. Services like Anti-CAPTCHA, 2Captcha, or DeathByCaptcha can be integrated into your scraping script to automate the CAPTCHA-solving process. You would need to modify your Pholcus code to send the CAPTCHA to the service and wait for the solved response before proceeding with the scraping.

3. Avoidance Strategies: Modify your scraping behavior to avoid triggering CAPTCHAs. This might include slowing down your request rate, changing IP addresses using proxies, using browser headers that mimic real user behavior, or using cookies to maintain a session that may be less likely to be presented with a CAPTCHA.

4. ReCAPTCHA Solving: For Google's reCAPTCHA, some services offer automated solving using various techniques, such as audio CAPTCHA solving or exploiting other weaknesses in the CAPTCHA system.

5. Advanced Techniques: Machine learning and image recognition techniques can sometimes be used to solve simple CAPTCHA challenges, although this approach requires significant expertise and resources to develop and maintain.

Here's a conceptual example of how you might integrate a CAPTCHA solving service into a Python-based web scraper (though Pholcus is Go-based, the idea is similar):

import requests
from captcha_solver import CaptchaSolver

solver = CaptchaSolver('2captcha', api_key='YOUR_2CAPTCHA_API_KEY')

def get_captcha_solution(captcha_image_url):
    raw_data = requests.get(captcha_image_url).content
    return solver.solve_captcha(raw_data)

# Imagine you've encountered a CAPTCHA on a page and extracted the image URL
captcha_image_url = 'http://example.com/captcha.jpg'
solution = get_captcha_solution(captcha_image_url)

# Now you can submit the solution along with your form or request

The CaptchaSolver class is a hypothetical class you would write to interact with the CAPTCHA solving service's API.

For Pholcus or another Go-based crawler, you'd write similar logic in Go, making HTTP requests to the solving service and handling the responses appropriately.

Keep in mind that using automated tools to bypass CAPTCHAs may violate the terms of service of the website you are scraping and could be considered unethical or even illegal, depending on the jurisdiction and specific circumstances. Always ensure that you have permission to scrape a site and that you are in compliance with any applicable laws and regulations.