adding miniFakeDns, a python-based mini DNS server, to use in testing

src/third_party/miniFakeDns/src/miniFakeDns.py

Index: src/third_party/miniFakeDns/src/miniFakeDns.py
diff --git a/src/third_party/miniFakeDns/src/miniFakeDns.py b/src/third_party/miniFakeDns/src/miniFakeDns.py
new file mode 100644
index 0000000000000000000000000000000000000000..8ffd4a47a0f89b456daf6241e4f0f0bf8f056c5a
--- /dev/null
+++ b/src/third_party/miniFakeDns/src/miniFakeDns.py
@@ -0,0 +1,43 @@
+import socket
+
+class DNSQuery:
+  def __init__(self, data):
+    self.data=data
+    self.dominio=''
+
+    tipo = (ord(data[2]) >> 3) & 15   # Opcode bits
+    if tipo == 0:                     # Standard query
+      ini=12
+      lon=ord(data[ini])
+      while lon != 0:
+        self.dominio+=data[ini+1:ini+lon+1]+'.'
+        ini+=lon+1
+        lon=ord(data[ini])
+
+  def respuesta(self, ip):
+    packet=''
+    if self.dominio:
+      packet+=self.data[:2] + "\x81\x80"
+      packet+=self.data[4:6] + self.data[4:6] + '\x00\x00\x00\x00'   # Questions and Answers Counts
+      packet+=self.data[12:]                                         # Original Domain Name Question
+      packet+='\xc0\x0c'                                             # Pointer to domain name
+      packet+='\x00\x01\x00\x01\x00\x00\x00\x3c\x00\x04'             # Response type, ttl and resource data length -> 4 bytes
+      packet+=str.join('',map(lambda x: chr(int(x)), ip.split('.'))) # 4bytes of IP
+    return packet
+
+if __name__ == '__main__':
+  ip='192.168.1.1'
+  print 'pyminifakeDNS:: dom.query. 60 IN A %s' % ip
+  
+  udps = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+  udps.bind(('',53))
+  
+  try:
+    while 1:
+      data, addr = udps.recvfrom(1024)
+      p=DNSQuery(data)
+      udps.sendto(p.respuesta(ip), addr)
+      print 'Respuesta: %s -> %s' % (p.dominio, ip)
+  except KeyboardInterrupt:
+    print 'Finalizando'
+    udps.close()