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Fix UDP DNS response not truncated

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世界 2024-02-01 12:10:39 +08:00
parent f76b21b02c
commit 17aebc56c1
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GPG Key ID: CD109927C34A63C4
1 changed files with 20 additions and 1 deletions
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21
outbound/dns.go
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@ -241,7 +241,8 @@ func (d *DNS) newPacketConnection(ctx context.Context, conn N.PacketConn, readWa
return err
}
timeout.Update()
responseBuffer := buf.NewPacket()
response = truncateDNSMessage(response, 512) // TODO: add an option to custom UDP buffer size
responseBuffer := buf.NewSize(dns.FixedPacketSize)
responseBuffer.Resize(1024, 0)
n, err := response.PackBuffer(responseBuffer.FreeBytes())
if err != nil {
@ -263,3 +264,21 @@ func (d *DNS) newPacketConnection(ctx context.Context, conn N.PacketConn, readWa
})
return group.Run(fastClose)
}
func truncateDNSMessage(response *mDNS.Msg, maxLen int) *mDNS.Msg {
responseLen := response.Len()
if responseLen <= maxLen {
return response
}
response = response.Copy()
for len(response.Answer) > 0 && responseLen > maxLen {
response.Answer = response.Answer[:len(response.Answer)-1]
response.Truncated = true
responseLen = response.Len()
}
if responseLen > maxLen {
response.Ns = nil
response.Extra = nil
}
return response
}