diff options
Diffstat (limited to 'project2/proj2_s4498062/dns/domainname.py')
| -rw-r--r-- | project2/proj2_s4498062/dns/domainname.py | 29 |
1 files changed, 14 insertions, 15 deletions
diff --git a/project2/proj2_s4498062/dns/domainname.py b/project2/proj2_s4498062/dns/domainname.py index 85e14bf..6dbb039 100644 --- a/project2/proj2_s4498062/dns/domainname.py +++ b/project2/proj2_s4498062/dns/domainname.py @@ -1,5 +1,3 @@ -#!/usr/bin/env python2 - """ Parsing and composing domain names This module contains two classes for converting domain names to and from bytes. @@ -14,20 +12,20 @@ import struct class Composer(object): def __init__(self): self.offsets = dict() - + def to_bytes(self, offset, dnames): # Convert each domain name in to bytes result = b"" - for i, dname in enumerate(dnames): + for _, dname in enumerate(dnames): # Split domain name into labels labels = dname.split(".") - + # Determine keys of subdomains in offset dict keys = [] for label in reversed(labels): name = label if keys: - name += "." + keys[-1] + name += "." + keys[-1] keys.append(name) keys.reverse() @@ -43,9 +41,10 @@ class Composer(object): break else: self.offsets[keys[j]] = offset - result += struct.pack("!B{}s".format(len(label)), - len(label), - label) + result += struct.pack( + "!B{}s".format(len(label)), + len(label), + label) offset += 1 + len(label) # Add null character at end @@ -61,11 +60,10 @@ class Parser(object): self.labels = dict() def from_bytes(self, packet, offset, num): - begin_offset = offset dnames = [] # Read the domain names - for i in range(num): + for _ in range(num): # Read a new domain name dname = "" prev_offsets = [] @@ -78,7 +76,7 @@ class Parser(object): if llength == 0: offset += 1 break - + # Compression label elif (llength >> 6) == 3: new_offset = offset + 2 @@ -90,8 +88,9 @@ class Parser(object): # Normal label else: new_offset = offset + llength + 1 - label = struct.unpack_from("{}s".format(llength), - packet, offset+1)[0] + label = struct.unpack_from( + "{}s".format(llength), + packet, offset+1)[0] # Add label to dictionary self.labels[offset] = label @@ -109,5 +108,5 @@ class Parser(object): # Append domain name to list dnames.append(dname) - + return dnames, offset |