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add dns.renderer.Renderer.add_multi_tsig() #2

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Merged
dhoeller merged 1 commit into from
Jan 12, 2018
Merged

add dns.renderer.Renderer.add_multi_tsig() #2

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38 changes: 36 additions & 2 deletions dns/renderer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -205,8 +205,6 @@ def add_tsig(self, keyname, secret, fudge, id, tsig_error, other_data,
request_mac, algorithm=dns.tsig.default_algorithm):
"""Add a TSIG signature to the message."""

self._set_section(ADDITIONAL)
before = self.output.tell()
s = self.output.getvalue()
(tsig_rdata, self.mac, ctx) = dns.tsig.sign(s,
keyname,
Expand All @@ -218,16 +216,52 @@ def add_tsig(self, keyname, secret, fudge, id, tsig_error, other_data,
other_data,
request_mac,
algorithm=algorithm)
self._write_tsig(tsig_rdata, keyname)

def add_multi_tsig(self, ctx, keyname, secret, fudge, id, tsig_error,
other_data, request_mac,
algorithm=dns.tsig.default_algorithm):
"""Add a TSIG signature to the message. Unlike add_tsig(), this can be
used for a series of consecutive DNS envelopes, e.g. for a zone
transfer over TCP [RFC2845, 4.4].

For the first message in the sequence, give ctx=None. For each
subsequent message, give the ctx that was returned from the
add_multi_tsig() call for the previous message."""

s = self.output.getvalue()
(tsig_rdata, self.mac, ctx) = dns.tsig.sign(s,
keyname,
secret,
int(time.time()),
fudge,
id,
tsig_error,
other_data,
request_mac,
ctx=ctx,
first=ctx is None,
multi=True,
algorithm=algorithm)
self._write_tsig(tsig_rdata, keyname)
return ctx

def _write_tsig(self, tsig_rdata, keyname):
self._set_section(ADDITIONAL)
before = self.output.tell()

keyname.to_wire(self.output, self.compress, self.origin)
self.output.write(struct.pack('!HHIH', dns.rdatatype.TSIG,
dns.rdataclass.ANY, 0, 0))
rdata_start = self.output.tell()
self.output.write(tsig_rdata)

after = self.output.tell()
assert after - rdata_start < 65536
if after >= self.max_size:
self._rollback(before)
raise dns.exception.TooBig

self.output.seek(rdata_start - 2)
self.output.write(struct.pack('!H', after - rdata_start))
self.counts[ADDITIONAL] += 1
Expand Down