67 lines
1.8 KiB
Go
67 lines
1.8 KiB
Go
package main
|
|
|
|
import "github.com/miekg/dns"
|
|
|
|
type PluginGetSetPayloadSize struct{}
|
|
|
|
func (plugin *PluginGetSetPayloadSize) Name() string {
|
|
return "get_set_payload_size"
|
|
}
|
|
|
|
func (plugin *PluginGetSetPayloadSize) Description() string {
|
|
return "Adjusts the maximum payload size advertised in queries sent to upstream servers."
|
|
}
|
|
|
|
func (plugin *PluginGetSetPayloadSize) Init(proxy *Proxy) error {
|
|
return nil
|
|
}
|
|
|
|
func (plugin *PluginGetSetPayloadSize) Drop() error {
|
|
return nil
|
|
}
|
|
|
|
func (plugin *PluginGetSetPayloadSize) Reload() error {
|
|
return nil
|
|
}
|
|
|
|
func (plugin *PluginGetSetPayloadSize) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
|
|
pluginsState.originalMaxPayloadSize = 512 - ResponseOverhead
|
|
edns0 := msg.IsEdns0()
|
|
dnssec := false
|
|
if edns0 != nil {
|
|
pluginsState.maxUnencryptedUDPSafePayloadSize = int(edns0.UDPSize())
|
|
pluginsState.originalMaxPayloadSize = Max(
|
|
pluginsState.maxUnencryptedUDPSafePayloadSize-ResponseOverhead,
|
|
pluginsState.originalMaxPayloadSize,
|
|
)
|
|
dnssec = edns0.Do()
|
|
}
|
|
var options *[]dns.EDNS0
|
|
pluginsState.dnssec = dnssec
|
|
pluginsState.maxPayloadSize = Min(
|
|
MaxDNSUDPPacketSize-ResponseOverhead,
|
|
Max(pluginsState.originalMaxPayloadSize, pluginsState.maxPayloadSize),
|
|
)
|
|
if pluginsState.maxPayloadSize > 512 {
|
|
extra2 := []dns.RR{}
|
|
for _, extra := range msg.Extra {
|
|
if extra.Header().Rrtype != dns.TypeOPT {
|
|
extra2 = append(extra2, extra)
|
|
} else if xoptions := &extra.(*dns.OPT).Option; len(*xoptions) > 0 && options == nil {
|
|
options = xoptions
|
|
}
|
|
}
|
|
msg.Extra = extra2
|
|
msg.SetEdns0(uint16(pluginsState.maxPayloadSize), dnssec)
|
|
if options != nil {
|
|
for _, extra := range msg.Extra {
|
|
if extra.Header().Rrtype == dns.TypeOPT {
|
|
extra.(*dns.OPT).Option = *options
|
|
break
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return nil
|
|
}
|