diff --git a/outbound/dns.go b/outbound/dns.go index fcb67d45..0f003377 100644 --- a/outbound/dns.go +++ b/outbound/dns.go @@ -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 +}