ShadowServer

shadowserver is an asynchronous HTTP proxy server library using aiohttp, designed to forward requests from clients to a target server. It handles HTTP and WebSocket connections, provides CORS support, and offers flexible SSL verification options, making it ideal for backend service proxying and server simulations in testing environments.

Features

• HTTP Proxying: Supports forwarding HTTP requests to a specified target.
• CORS Support: Automatically adds headers to enable cross-origin requests.
• WebSocket Support: Forwards WebSocket connections between client and target server.
• Flexible SSL Verification: Allows disabling SSL verification for outgoing HTTPS requests.
• Route Support: Ability to append a custom route to the proxy server URL.
• Asynchronous Design: Built with aiohttp for handling multiple concurrent requests efficiently.

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Installation

You can install shadowserver via pip:

pip install shadowserver

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Usage

Below is a basic example of how to set up and run shadowserver.

Basic Example

from shadowserver import ShadowServer
import asyncio

async def main():
    # Initialize the server with the target URL and optional settings
    proxy = ShadowServer(
        target_base_url="https://example.com",
        timeout=30,
        max_conn=100,
        open_on_browser=True,
        verify_ssl=True
    )

    # Start the server
    await proxy.start_server(host="127.0.0.1", port=8080)

# Run the server
asyncio.run(main())

Disabling SSL Verification

To disable SSL verification for outgoing HTTPS requests, pass verify_ssl=False during initialization:

proxy = ShadowServer(
    target_base_url="https://example.com",
    verify_ssl=False  # Disables SSL verification for HTTPS requests
)

This can be useful for development environments where the target server uses a self-signed certificate.

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ShadowServer URL Redirection

The ShadowServer class includes an optional redirect feature to automatically redirect requests from the base URL to a specified URL. This is enabled by passing a redirect_url and setting redirects=True.

Parameters

• redirect_url: str
  The URL to redirect to when the base URL (/) is accessed.
• redirects: bool
  Enables or disables the redirect from the base URL to redirect_url.

Example Usage

Here are some examples showing how to configure the ShadowServer with URL redirection.

Example 1: Redirecting Requests from Base URL to Another URL

In this example, requests to the base URL (/) will be redirected to the URL specified in redirect_url:

from shadowserver import ShadowServer
import asyncio

BASE_URL = "https://example.com/api"
REDIRECT_URL = "https://example.com/home"

server = ShadowServer(
    target_base_url=BASE_URL,
    redirect_url=REDIRECT_URL,
    redirects=True
)

asyncio.run(server.start_server(
    host="127.0.0.1",
    port=3000
))

• Requests to http://127.0.0.1:3000/ will automatically redirect to https://example.com/home.
• All other requests (e.g., http://127.0.0.1:3000/some/path) will be proxied to https://example.com/api/some/path.

Example 2: Disabling Redirection

To use ShadowServer as a proxy without redirection, omit redirect_url and set redirects=False:

from shadowserver import ShadowServer
import asyncio

BASE_URL = "https://example.com/api"

server = ShadowServer(
    target_base_url=BASE_URL,
    redirects=False  # Disables redirection
)

asyncio.run(server.start_server(
    host="127.0.0.1",
    port=3000
))

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Advanced Configuration

Setting a Custom Route

You can specify a custom route that will be appended to the base URL. This is useful when you want the server to be accessible via a specific route.

proxy = ShadowServer(
    target_base_url="https://example.com",
    route="/customroute"
)

asyncio.run(proxy.start_server(host="127.0.0.1", port=8080))

Setting Timeout and Maximum Connections

To configure custom timeouts and connection limits during initialization:

proxy = ShadowServer(target_base_url="https://example.com", timeout=60, max_conn=200)

This example sets a 60-second timeout and allows up to 200 concurrent connections.

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API Reference

ShadowServer

The main class for setting up and running the proxy server.

class ShadowServer:
    def __init__(self, target_base_url, timeout=30, max_conn=100)

• Parameters:
  • target_base_url (str): The base URL to which all proxied requests are forwarded.
  • timeout (int, optional): Timeout in seconds for requests to the target server. Default is 30.
  • max_conn (int, optional): Maximum number of concurrent connections. Default is 100.
  • redirect_url (str, optional): URL for redirecting requests from the base URL.
  • redirects (bool, optional): If True, enables redirection to redirect_url. Default is False.
  • open_on_browser (bool, optional): Automatically opens the server URL in a browser when started. Default is True.
  • verify_ssl (bool, optional): If False, disables SSL verification. Default is True.
  • route (str, optional): Appends a custom route to the server URL.

Methods

1. start_server

   async def start_server(self, host='127.0.0.1', port=8080)
   

   Starts the proxy server.

   • Parameters:

     • host (str, optional): The host IP on which the server runs. Default is '127.0.0.1'.
     • port (int, optional): The port on which the server listens. Default is 8080.

2. close

   async def close(self)
   

   Closes the server session and frees up resources.

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Request Handling

The ShadowServer proxy server processes requests as follows:

1. handle_request: Forwards HTTP and HTTPS requests to the target server and returns the response to the client.
2. handle_websocket: Forwards WebSocket connections to the target server.
3. build_response: Builds the response, applies custom headers (such as CORS), and sends it to the client.

Example of Proxying a GET Request

Once the server is running, you can make a GET request to any endpoint available on the target server:

curl http://127.0.0.1:8080/api/resource

This request will be proxied to https://example.com/api/resource.

WebSocket Proxying

The proxy supports WebSocket connections. You can connect to the WebSocket server via the proxy as shown below:

import websockets
import asyncio

async def connect():
    uri = "ws://127.0.0.1:8080/socket"
    async with websockets.connect(uri) as websocket:
        await websocket.send("Hello, World!")
        response = await websocket.recv()
        print(response)

asyncio.run(connect())

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Troubleshooting

CORS Errors

If you encounter CORS issues, ensure that the client request headers include the correct Origin.

SSL Verification Errors

To disable SSL verification, set verify_ssl=False when initializing the server.