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dns: add HTTPS resource record type packing/unpacking (#676) #677

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dns: add HTTPS resource record type packing/unpacking (#676) #677

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48 changes: 48 additions & 0 deletions dpkt/dns.py
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,7 @@
DNS_AAAA = 28
DNS_SRV = 33
DNS_OPT = 41
DNS_HTTPS = 65

# RR classes
DNS_IN = 1
Expand Down Expand Up @@ -300,6 +301,15 @@ def pack_rdata(self, off, label_ptrs):
pack_name(self.srvname, off + 6, label_ptrs)
elif self.type == DNS_OPT:
return b'' # self.rdata
elif self.type == DNS_HTTPS:
l_ = []
l_.append(struct.pack('>H', self.svcpriority))
l_.append(pack_name(self.targetname, 0, {}))
for p in self.svcparams:
l_.append(struct.pack('>H', p[0])) # key
l_.append(struct.pack('>H', len(p[1]))) # value len
l_.append(p[1]) # value
return b''.join(l_)
else:
raise dpkt.PackError('RR type %s is not supported' % self.type)

Expand Down Expand Up @@ -336,6 +346,17 @@ def unpack_rdata(self, buf, off):
self.srvname, off = unpack_name(buf, off + 6)
elif self.type == DNS_OPT:
pass # RFC-6891: OPT is a pseudo-RR not carrying any DNS data
elif self.type == DNS_HTTPS:
self.svcpriority, = struct.unpack('>H', buf[off:off + 2])
off += 2
self.targetname, off = unpack_name(buf, off)
self.svcparams = []
while off < len(buf):
key, valuelen = struct.unpack('>HH', buf[off:off + 4])
off += 4
value = buf[off:off + valuelen]
self.svcparams.append((key, value))
off += valuelen
else:
raise dpkt.UnpackError('RR type %s is not supported' % self.type)

Expand Down Expand Up @@ -427,6 +448,11 @@ class TestData(object):
"a154818000010001000000000377777705676d61696c03636f6d0000010001c00"
"c000500010000545f000e046d61696c06676f6f676c65c016"
)
https_resp = unhexlify(
"9c3a8180000100010000000008796f7574756265690a676f6f676c65617069730"
"3636f6d0000410001c00c0041000100000723000d000100000100060268320268"
"33"
)
invalid_rr = unhexlify(
"000001000000000100000000046e616d650000150001000000000000"
)
Expand Down Expand Up @@ -782,6 +808,28 @@ def test_rdata_OPT():
assert packdata == correct


def test_rdata_HTTPS():
buf = define_testdata().https_resp
my_dns = DNS(buf)
assert my_dns.an[0].svcpriority == 1
assert my_dns.an[0].targetname == ''
assert len(my_dns.an[0].svcparams) == 1
key, value = my_dns.an[0].svcparams[0]
assert key == 1
assert value == b'\x02h2\x02h3'

rr = DNS.RR(
type=DNS_HTTPS,
svcpriority=1,
targetname="svc2.example.net",
svcparams=[(1, b'\x02h2\x02h3')],
)

packdata = rr.pack_rdata(9, {})
correct = b'\x00\x01\x04svc2\x07example\x03net\x00\x00\x01\x00\x06\x02h2\x02h3'
assert packdata == correct


def test_dns_len():
my_dns = DNS()
assert len(my_dns) == 12
Expand Down