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author | 2018-12-04 20:15:57 +0000 | |
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committer | 2018-12-04 20:15:57 +0000 | |
commit | 59a49c5ff7eeb6dad2e38ce8ccd5c4682e087005 (patch) | |
tree | 2bbb94f67f9299a246dc2f5c30eafa54e950e47b /request | |
parent | b53cc51f5310b82e04d687b8b25783cfd972383c (diff) | |
download | coredns-59a49c5ff7eeb6dad2e38ce8ccd5c4682e087005.tar.gz coredns-59a49c5ff7eeb6dad2e38ce8ccd5c4682e087005.tar.zst coredns-59a49c5ff7eeb6dad2e38ce8ccd5c4682e087005.zip |
Scrub: Do more to avoid fragmentation (#2333)
Automatically submitted.
Diffstat (limited to 'request')
-rw-r--r-- | request/request.go | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/request/request.go b/request/request.go index 260d73f5e..105cd8528 100644 --- a/request/request.go +++ b/request/request.go @@ -240,6 +240,23 @@ func (r *Request) Scrub(reply *dns.Msg) *dns.Msg { reply.Compress = false rl := reply.Len() if size >= rl { + if r.Proto() != "udp" { + return reply + } + + // Last ditch attempt to avoid fragmentation, if the size is bigger than the v4/v6 UDP fragmentation + // limit and sent via UDP compress it (in the hope we go under that limit). Limits taken from NSD: + // + // .., 1480 (EDNS/IPv4), 1220 (EDNS/IPv6), or the advertized EDNS buffer size if that is + // smaller than the EDNS default. + // See: https://open.nlnetlabs.nl/pipermail/nsd-users/2011-November/001278.html + if rl > 1480 && r.Family() == 1 { + reply.Compress = true + } + if rl > 1220 && r.Family() == 2 { + reply.Compress = true + } + return reply } |