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Update doc for Truncate (#1173) 

Follow up after #1171, update the docs about TC and use the MinMsgSize
constant for 512 in the code.

Signed-off-by: Miek Gieben <miek@miek.nl>
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Miek Gieben 2020-10-14 08:42:57 +02:00 committed by GitHub
parent 5579226123
commit ef286f8f39
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1 changed files with 5 additions and 4 deletions
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9
msg_truncate.go
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@ -9,7 +9,8 @@ package dns
// requested buffer size.
//
// The TC bit will be set if any records were excluded from the message.
// This indicates to that the client should retry over TCP.
// If the TC bit is already set on the message it will be retained.
// TC indicates that the client should retry over TCP.
//
// According to RFC 2181, the TC bit should only be set if not all of the
// "required" RRs can be included in the response. Unfortunately, we have
@ -28,11 +29,11 @@ func (dns *Msg) Truncate(size int) {
}
// RFC 6891 mandates that the payload size in an OPT record
// less than 512 bytes must be treated as equal to 512 bytes.
// less than 512 (MinMsgSize) bytes must be treated as equal to 512 bytes.
//
// For ease of use, we impose that restriction here.
if size < 512 {
size = 512
if size < MinMsgSize {
size = MinMsgSize
}
l := msgLenWithCompressionMap(dns, nil) // uncompressed length