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Add EDNS ECSOption #74

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Add EDNS ECSOption #74

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34 changes: 33 additions & 1 deletion dnslib/dns.py
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Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,9 @@ def unknown_qtype(name,key,forward):
OPCODE = Bimap('OPCODE',{0:'QUERY', 1:'IQUERY', 2:'STATUS', 4:'NOTIFY', 5:'UPDATE'},
DNSError)

EDNS0OPT = Bimap('EDNS0OPT',{8:'ECS'},
DNSError)

def label(label,origin=None):
if label.endswith("."):
return DNSLabel(label)
Expand Down Expand Up @@ -798,6 +801,32 @@ def __eq__(self,other):
attrs = ('code','data')
return all([getattr(self,x) == getattr(other,x) for x in attrs])

class ECSOption(EDNSOption):

family = H('family')
src_prefix_len = B('src_prefix_len')
scope_prefix_len = B('scope_prefix_len')

def __init__(self,code,data):
super(ECSOption,self).__init__(code,data)
self.family,self.src_prefix_len,self.scope_prefix_len = struct.unpack("!HBB",data[:4])
self.addr_bytes = data[4:]
self.total_bytes = (self.src_prefix_len + 7) // 8
self.address = self.addr_bytes[:self.total_bytes] + b"\x00" * (4**self.family - self.total_bytes)

def pack(self,buffer):
addr_bytes = self.addr_bytes[:self.total_bytes]
option_data = struct.pack("!HBB", self.family,
self.src_prefix_len,
self.scope_prefix_len) + addr_bytes

buffer.pack("!HH", self.code, len(option_data))
buffer.append(option_data)

def toZone(self):
return "; EDNS: code %s, - family: %i; prefix length: %i; scope length: %i; address: %s" % (
self.code,self.family,self.src_prefix_len,self.scope_prefix_len,self.address)

class RR(object):

"""
Expand All @@ -821,7 +850,10 @@ def parse(cls,buffer):
while option_buffer.remaining() > 4:
code,length = option_buffer.unpack("!HH")
data = option_buffer.get(length)
options.append(EDNSOption(code,data))
if(code == EDNS0OPT.ECS):
options.append(ECSOption(code,data))
else:
options.append(EDNSOption(code,data))
rdata = options
else:
if rdlength:
Expand Down