Fix various issues when validating DNS response packets #27774
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ceolin
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ceolin
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Aug 25, 2020
This is not possible with valid DNS messages but is possible if we receive malformed DNS packet. Signed-off-by: Jukka Rissanen <[email protected]>
Make sure that IP address information is found in the received message. Signed-off-by: Jukka Rissanen <[email protected]>
As the answer might not be compressed, calculate next answer position correctly. Signed-off-by: Jukka Rissanen <[email protected]>
The ANCOUNT has nothing to do with label count so remove the original while loop and just go through all the labels until we have read all of them. Signed-off-by: Jukka Rissanen <[email protected]>
The DNS message must be long enough for id and flags fields. Signed-off-by: Jukka Rissanen <[email protected]>
Add more tests to verify that we discard malformed packets. In order to simplify the testing, separate message validation to dns_validate_msg() function in resolve.c. Allow that function to be called from unit test. This way we can construct invalid DNS messages in unit test and verify that they are discarded when needed. Signed-off-by: Jukka Rissanen <[email protected]>
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d3zd3z
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tbursztyka
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There is also a commit that tries to verify that we catch all the fixed issues.