added catchall dns implementation

__init__.py

@@ -1,5 +1,5 @@
 # phew! the Pico (or Python) HTTP Endpoint Wrangler
-from .phew import server, logging, connect_to_wifi
+from .phew import server, logging, dns, connect_to_wifi
 
 from .phew.server import redirect, serve_file
 from .phew.template import render_template

phew/dns.py

@@ -0,0 +1,32 @@
+import uasyncio, usocket
+from . import logging
+
+async def _handler(socket, ip_address):
+  while True:
+    try:
+      yield uasyncio.core._io_queue.queue_read(socket)
+      request, client = socket.recvfrom(256)
+      response = request[:2] # request id
+      response += b"\x81\x80" # response flags
+      response += request[4:6] + request[4:6] # qd/an count
+      response += b"\x00\x00\x00\x00" # ns/ar count
+      response += request[12:] # origional request body
+      response += b"\xC0\x0C" # pointer to domain name at byte 12
+      response += b"\x00\x01\x00\x01" # type and class (A record / IN class)
+      response += b"\x00\x00\x00\x3C" # time to live 60 seconds
+      response += b"\x00\x04" # response length (4 bytes = 1 ipv4 address)
+      response += bytes(map(int, ip_address.split("."))) # ip address parts
+      socket.sendto(response, client)
+    except Exception as e:
+      logging.error(e)
+
+def run_catchall(ip_address, port = 53):
+  logging.info("> starting catch all dns server on port {}".format(port))
+
+  _socket = usocket.socket(usocket.AF_INET, usocket.SOCK_DGRAM)
+  _socket.setblocking(False)
+  _socket.setsockopt(usocket.SOL_SOCKET, usocket.SO_REUSEADDR, 1)
+  _socket.bind(usocket.getaddrinfo(ip_address, port, 0, usocket.SOCK_DGRAM)[0][-1])
+
+  loop = uasyncio.get_event_loop()
+  loop.create_task(_handler(_socket, ip_address))

phew/server.py

@@ -348,7 +348,7 @@ def serve_file(file):
 
 
 def run(host = "0.0.0.0", port = 80):
-  logging.info("> starting webserver on port {}".format(port))
+  logging.info("> starting web server on port {}".format(port))
 
   loop = uasyncio.get_event_loop()
   loop.create_task(uasyncio.start_server(_handle_request, host, port))