Proxy

starlette/proxy.py

@@ -0,0 +1,40 @@
+from starlette.request import Request
+from starlette.response import Response
+from urllib.parse import unquote
+import asyncio
+import aiohttp
+
+
+class Proxy:
+    def __init__(self, base_url, max_concurrency=20):
+        self.base_url = base_url
+        self.session = None
+        self.semaphore = asyncio.Semaphore(max_concurrency)
+
+    def __call__(self, scope):
+        if self.session is None:
+            self.session = aiohttp.ClientSession()
+        return _ProxyResponder(scope, self.base_url, self.session, self.semaphore)
+
+
+class _ProxyResponder:
+    def __init__(self, scope, base_url, session, semaphore):
+        self.scope = scope
+        self.base_url = base_url
+        self.session = session
+        self.semaphore = semaphore
+
+    async def __call__(self, receive, send):
+        request = Request(self.scope, receive)
+        method = request.method
+        url = self.base_url + request.relative_url
+        headers = request.headers.mutablecopy()
+        del headers["host"]
+        headers["connection"] = "keep-alive"
+        data = await request.body()
+        kwargs = {"method": method, "url": url, "data": data, "headers": headers}
+        async with self.semaphore:
+            original = await self.session.request(**kwargs)
+            body = await original.read()
+        response = Response(body, status_code=original.status, headers=original.headers)
+        await response(receive, send)