64 lines
1.6 KiB
Go
64 lines
1.6 KiB
Go
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package main
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import (
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"github.com/miekg/dns"
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)
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type PluginsAction int
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const (
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PluginsActionNone = 0
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PluginsActionForward = 1
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)
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type PluginsState struct {
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sessionData map[string]interface{}
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action PluginsAction
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originalMaxPayloadSize int
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maxPayloadSize int
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proto string
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}
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func NewPluginsState() PluginsState {
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return PluginsState{action: PluginsActionForward, maxPayloadSize: MaxDNSUDPPacketSize - ResponseOverhead}
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}
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func (pluginsState *PluginsState) ApplyQueryPlugins(packet []byte) ([]byte, error) {
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msg := dns.Msg{}
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if err := msg.Unpack(packet); err != nil {
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return packet, err
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}
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if ret := pluginsState.BuiltinPluginsGetSetPayloadSize(&msg); ret != nil {
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return packet, ret
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}
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packet2, err := msg.PackBuffer(packet)
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if err != nil {
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return packet, err
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}
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return packet2, nil
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}
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func (pluginsState *PluginsState) BuiltinPluginsGetSetPayloadSize(msg *dns.Msg) error {
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pluginsState.originalMaxPayloadSize = 512 - ResponseOverhead
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opt := msg.IsEdns0()
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dnssec := false
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if opt != nil {
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pluginsState.originalMaxPayloadSize = Min(int(opt.UDPSize())-ResponseOverhead, pluginsState.originalMaxPayloadSize)
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dnssec = opt.Do()
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}
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pluginsState.maxPayloadSize = Min(MaxDNSUDPPacketSize-ResponseOverhead, Max(pluginsState.originalMaxPayloadSize, pluginsState.maxPayloadSize))
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if pluginsState.maxPayloadSize > 512 {
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extra2 := []dns.RR{}
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for _, extra := range msg.Extra {
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if extra.Header().Rrtype != dns.TypeOPT {
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extra2 = append(extra2, extra)
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}
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}
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msg.Extra = extra2
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msg.SetEdns0(uint16(pluginsState.maxPayloadSize), dnssec)
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}
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return nil
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}
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