Add an example of modifying the headers

Author: julien-duponchelle

examples/modify_request_header.py

@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+"""
+An example of how to modify HTTP headers with asyncio-https-proxy.
+
+This example demonstrates how to create a custom proxy handler to intercept
+and modify HTTP requests before they are forwarded to the destination server.
+"""
+
+import asyncio
+
+from asyncio_https_proxy import HTTPSForwardProxyHandler, TLSStore, start_proxy_server
+
+
+class ModifyHeaderHandler(HTTPSForwardProxyHandler):
+    """
+    A custom proxy handler that adds a 'X-Custom-Header' to all requests.
+    """
+
+    async def on_request_received(self):
+        """
+        Intercept the request and add a custom header.
+        """
+        print(f"Original request headers for {self.request.url()}:")
+        for key, value in self.request.headers:
+            print(f"  {key}: {value}")
+
+        # Add a custom header to the request
+        self.request.headers.headers.append(
+            ("X-Custom-Header", "Hello from the proxy!")
+        )
+
+        print("\nModified request headers:")
+        for key, value in self.request.headers:
+            print(f"  {key}: {value}")
+        print("---")
+
+        # Continue with the default request forwarding
+        await super().on_request_received()
+
+
+async def main():
+    """
+    Run the modifying forward proxy.
+    """
+
+    host = "127.0.0.1"
+    port = 8888
+
+    print(f"Starting HTTPS forward proxy on {host}:{port}")
+    print("This proxy will add a 'X-Custom-Header' to all requests.")
+    print("\nTest the proxy with:")
+    print(f"  curl --insecure --proxy http://{host}:{port} https://httpbin.org/headers")
+    print("\nPress Ctrl+C to stop the proxy")
+
+    # Initialize the TLS store for HTTPS interception
+    tls_store = TLSStore.generate_ca(
+        country="FR",
+        state="Ile-de-France",
+        locality="Paris",
+        organization="Modify Header Example",
+        common_name="Modify Header CA",
+    )
+
+    server = await start_proxy_server(
+        handler_builder=lambda: ModifyHeaderHandler(),
+        host=host,
+        port=port,
+        tls_store=tls_store,
+    )
+
+    async with server:
+        try:
+            await server.serve_forever()
+        except KeyboardInterrupt:
+            print("Shutting down proxy...")
+            server.close()
+            await server.wait_closed()
+            print("Proxy shut down.")
+
+
+if __name__ == "__main__":
+    asyncio.run(main())