Define DeviceDNSMap: class the stores a specific device's DNS mappings.

diff --git a/parse_dns.py b/parse_dns.py
index 7c58c358761c497640f6544613fb2dcd1cb8858f..3bb7d0bf506c53ac96434ab523f120eeb314f55d 100644 (file)
--- a/parse_dns.py
+++ b/parse_dns.py
@@ -46,6 +46,46 @@ def main():
                        print "    -", hn
        print "====================================================================="
 
+class DeviceDNSMap:
+       def __init__(self, mac_address):
+               # MAC address of device
+               self.mac = mac_address
+               # Maps an external IP to a list of (timestamp,hostname) tuples.
+               # Entries in the list should be interpreted as follows:
+               # the timestamp indicates WHEN this device mapped the given ip (key in dict) to the hostname.
+               self.ip_mappings = defaultdict(list)
+
+       def hostname_for_ip_at_time(self, ip, timestamp):
+               # Does device have a mapping for the given IP?
+               if not ip in self.ip_mappings:
+                       return None
+               if not self.ip_mappings[ip]:
+                       # If list of (timestamp,hostname) tuples is empty, there is no mapping to report.
+                       return None
+               # Best fit mapping: the mapping immediately BEFORE timestamp parameter.
+               # Start with random pick (element 0).
+               best_fit = self.ip_mappings[ip][0]
+               for t in self.ip_mappings[ip]:
+                       # t is a (timestamp,hostname) tuple
+                       if t[0] < timestamp and t[0] > best_fit[0]:
+                               # t is a better fit if it happened BEFORE the input timestamp
+                               # and is LATER than the current best_fit
+                               best_fit = t
+               return best_fit
+
+       def add_mapping(self, ip, timestamp_hostname_tuple):
+               self.ip_mappings[ip].add(timestamp_hostname_tuple)
+
+       # --------------------------------------------------------------------------
+       # Define eq and hash such that instances of the class can be used as keys in dictionaries.
+       # Equality is based on MAC as a MAC uniquely identifies the device.
+       def __eq__(self, another):
+       return hasattr(another, 'mac') and self.mac == another.mac
+       def __hash__(self):
+               return hash(self.data)
+       # --------------------------------------------------------------------------
+
+
 # Convert JSON file containing DNS traffic to a tuple with two maps.
 # Index 0 of the tuple is a map in which a hostname points to its set of associated IPs.
 # Index 1 of the tuple is a map in which an ip points to its set of associated hostnames.