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DNS query with small edns bufsize fail #404

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MaltertheGreat opened this issue Jan 16, 2021 · 1 comment
Closed

DNS query with small edns bufsize fail #404

MaltertheGreat opened this issue Jan 16, 2021 · 1 comment

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@MaltertheGreat
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MaltertheGreat commented Jan 16, 2021 •
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According to https://tools.ietf.org/html/rfc6891#section-6.2.3 responder should round the 'UDP Payload Size' up to 512 (at least I think so). However, for values smaller than 12 Unbound returns SERVFAIL.

How to reproduce:

dig +bufsize=0 +edns .

Expected output:

DNS record for '.'

Acctual output:

SERVFAIL
@wcawijngaards
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There is an option to make unbound behave like this: harden-short-bufsize: yes in unbound.conf.
https://www.nlnetlabs.nl/documentation/unbound/unbound.conf/#harden-short-bufsize

But the default is 'off' for this option. The default can be on if you think that is more compliant with the RFC.

jedisct1 added a commit to jedisct1/unbound that referenced this issue Jan 20, 2021
@jedisct1
Merge remote-tracking branch 'nlnet/master'
3ea27d7 
* nlnet/master: (33 commits)
  rpl tests for nsid
  example.conf.in entry for nsid
  - Fix declaration before statement and signed comparison warning in   dns64.
  - Fix NLnetLabs#404: DNS query with small edns bufsize fail.
  Changelog entry for NLnetLabs#402. - Merge NLnetLabs#402 from fobser: Implement IPv4-Embedded addresses according   to RFC6052.
  Implement IPv4-Embedded addresses according to RFC6052.
  - Fix for NLnetLabs#93: dynlibmodule import library is named libunbound.dll.a.
  - Fix for NLnetLabs#93: dynlibmodule link fix for Windows.
  Nicer changelog note for NLnetLabs#399 - Merge NLnetLabs#399 from xiangbao227: The lock of lruhash table should   unlocked after markdel entry.
  Changelog note for NLnetLabs#399 - Merge NLnetLabs#399 from xiangbao227: The function rrset_cache_touch can   touch an entry to the lru while markdelling the entry in   lruhash_remove.
  I found that in function lruhash_remove, table was locked at first ,then lru_remove the entry , then unlock the table, and then markdel entry , but in function rrset_cache_touch , the entry will be touched to lru again before markdelling entry in function lruhash_remove. This is a bug!
  And man page documentation for them.
  - Fix so local zone types always_nodata and always_deny can be used   from the config file.
  - Fix NLnetLabs#397: [Feature request] add new type always_null to local-zone   similar to always_nxdomain.
  - Fix clang analysis warning.
  - Add comment documentation.
  - For NLnetLabs#391: more double casts in python start time calculation.
  - For NLnetLabs#391: fix indentation.
  - For NLnetLabs#391: use struct timeval* start_time for callback information.
  Changelog note for NLnetLabs#391 - Merge PR NLnetLabs#391 from fhriley: Add start_time to reply callbacks so   modules can compute the response time.
  ...
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@wcawijngaards @MaltertheGreat