dnscrypt-proxy/dnscrypt-proxy/plugin_get_set_payload_size.go

49 lines
1.3 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
opt := msg.IsEdns0()
dnssec := false
if opt != nil {
pluginsState.originalMaxPayloadSize = Min(int(opt.UDPSize())-ResponseOverhead, pluginsState.originalMaxPayloadSize)
dnssec = opt.Do()
}
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)
}
}
msg.Extra = extra2
msg.SetEdns0(uint16(pluginsState.maxPayloadSize), dnssec)
}
return nil
}