respondc.py

lib/respondc.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+import socket
+import zlib
+import json
+import sys
+
+def request(ifname, request, target='ff02::2', timeout=0.5, singleshot=False):
+  try:
+    if_id = socket.if_nametoindex(ifname)
+  except OSError:
+    print('interface \'{}\' not found'.format(sys.argv[1]), file=sys.stderr)
+    return []
+
+  sock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
+
+  # request
+  message = bytes('GET {}'.format(request), 'utf-8')
+  sock.sendto(message, (target, 1001, 0, if_id))
+
+  print('+ {:s}'.format(str(message)), file=sys.stderr)
+
+  sock.settimeout(timeout)
+
+  # receive
+  responses = {}
+  rsp, err = 0, 0
+  while True:
+    print('\r+ {rsp} responses, {err} errors'.format(**locals()), end='', file=sys.stderr)
+
+    try:
+      buffer, address = sock.recvfrom(2048)
+    except socket.timeout:
+      print('\n+ no replies for %f seconds, continuing...' % timeout, file=sys.stderr)
+      break
+
+    try:
+      source = address[0].split('%')[0]
+      data = zlib.decompress(buffer, -15)
+      nodeinfo = json.loads(data.decode('utf-8'))
+      responses[source] = nodeinfo
+      rsp += 1
+    except (zlib.error, UnicodeDecodeError, ValueError):
+      err += 1
+      print('- unreadable answer from {addr}'.format(addr=source), file=sys.stderr)
+
+    if singleshot:
+      break
+
+  return responses.values()
+