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Skip getting a server candidate if unnecessary #2948

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72a5926
Skip getting a server candidate if unnecessary
lifenjoiner Sep 6, 2025
5b573a2
Skip getting a server candidate if unnecessary: reduce coupling
lifenjoiner Sep 7, 2025
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109 changes: 59 additions & 50 deletions dnscrypt-proxy/plugins.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import (
"time"

"github.com/jedisct1/dlog"
stamps "github.com/jedisct1/go-dnsstamps"
"github.com/miekg/dns"
)

Expand Down Expand Up @@ -273,58 +274,64 @@ func NewPluginsState(
func (pluginsState *PluginsState) ApplyQueryPlugins(
pluginsGlobals *PluginsGlobals,
packet []byte,
needsEDNS0Padding bool,
) ([]byte, error) {
getServerInfo func() *ServerInfo,
) ([]byte, *ServerInfo, error) {
msg := dns.Msg{}
if err := msg.Unpack(packet); err != nil {
return packet, err
return packet, nil, err
}
if len(msg.Question) != 1 {
return packet, errors.New("Unexpected number of questions")
return packet, nil, errors.New("Unexpected number of questions")
}
qName, err := NormalizeQName(msg.Question[0].Name)
if err != nil {
return packet, err
return packet, nil, err
}
dlog.Debugf("Handling query for [%v]", qName)
pluginsState.qName = qName
pluginsState.questionMsg = &msg
if len(*pluginsGlobals.queryPlugins) == 0 && len(*pluginsGlobals.loggingPlugins) == 0 {
return packet, nil
}
pluginsGlobals.RLock()
defer pluginsGlobals.RUnlock()
for _, plugin := range *pluginsGlobals.queryPlugins {
if err := plugin.Eval(pluginsState, &msg); err != nil {
pluginsState.action = PluginsActionDrop
return packet, err
}
if pluginsState.action == PluginsActionReject {
synth := RefusedResponseFromMessage(
&msg,
pluginsGlobals.refusedCodeInResponses,
pluginsGlobals.respondWithIPv4,
pluginsGlobals.respondWithIPv6,
pluginsState.rejectTTL,
)
pluginsState.synthResponse = synth
}
if pluginsState.action != PluginsActionContinue {
break
if len(*pluginsGlobals.queryPlugins) > 0 {
pluginsGlobals.RLock()
for _, plugin := range *pluginsGlobals.queryPlugins {
if err := plugin.Eval(pluginsState, &msg); err != nil {
pluginsState.action = PluginsActionDrop
return packet, nil, err
}
if pluginsState.action == PluginsActionReject {
synth := RefusedResponseFromMessage(
&msg,
pluginsGlobals.refusedCodeInResponses,
pluginsGlobals.respondWithIPv4,
pluginsGlobals.respondWithIPv6,
pluginsState.rejectTTL,
)
pluginsState.synthResponse = synth
}
if pluginsState.action != PluginsActionContinue {
break
}
}
pluginsGlobals.RUnlock()
}
needsEDNS0Padding := false
var serverInfo *ServerInfo
if pluginsState.action == PluginsActionContinue {
serverInfo = getServerInfo()
}
if serverInfo != nil {
needsEDNS0Padding = (serverInfo.Proto == stamps.StampProtoTypeDoH || serverInfo.Proto == stamps.StampProtoTypeTLS)
}

packet2, err := msg.PackBuffer(packet)
if err != nil {
return packet, err
return packet, serverInfo, err
}
if needsEDNS0Padding && pluginsState.action == PluginsActionContinue {
padLen := 63 - ((len(packet2) + 63) & 63)
if paddedPacket2, _ := addEDNS0PaddingIfNoneFound(&msg, packet2, padLen); paddedPacket2 != nil {
return paddedPacket2, nil
return paddedPacket2, serverInfo, nil
}
}
return packet2, nil
return packet2, serverInfo, nil
}

func (pluginsState *PluginsState) ApplyResponsePlugins(
Expand All @@ -350,26 +357,28 @@ func (pluginsState *PluginsState) ApplyResponsePlugins(
pluginsState.returnCode = PluginsReturnCodeResponseError
}
removeEDNS0Options(&msg)
pluginsGlobals.RLock()
defer pluginsGlobals.RUnlock()
for _, plugin := range *pluginsGlobals.responsePlugins {
if err := plugin.Eval(pluginsState, &msg); err != nil {
pluginsState.action = PluginsActionDrop
return packet, err
}
if pluginsState.action == PluginsActionReject {
synth := RefusedResponseFromMessage(
&msg,
pluginsGlobals.refusedCodeInResponses,
pluginsGlobals.respondWithIPv4,
pluginsGlobals.respondWithIPv6,
pluginsState.rejectTTL,
)
pluginsState.synthResponse = synth
}
if pluginsState.action != PluginsActionContinue {
break
if len(*pluginsGlobals.responsePlugins) > 0 {
pluginsGlobals.RLock()
for _, plugin := range *pluginsGlobals.responsePlugins {
if err := plugin.Eval(pluginsState, &msg); err != nil {
pluginsState.action = PluginsActionDrop
return packet, err
}
if pluginsState.action == PluginsActionReject {
synth := RefusedResponseFromMessage(
&msg,
pluginsGlobals.refusedCodeInResponses,
pluginsGlobals.respondWithIPv4,
pluginsGlobals.respondWithIPv6,
pluginsState.rejectTTL,
)
pluginsState.synthResponse = synth
}
if pluginsState.action != PluginsActionContinue {
break
}
}
pluginsGlobals.RUnlock()
}
if ttl != nil {
setMaxTTL(&msg, *ttl)
Expand Down
15 changes: 5 additions & 10 deletions dnscrypt-proxy/proxy.go
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Original file line number Diff line number Diff line change
Expand Up @@ -713,17 +713,11 @@ func (proxy *Proxy) processIncomingQuery(
// Initialize plugin state
pluginsState := NewPluginsState(proxy, clientProto, clientAddr, serverProto, start)

// Get server info and initialize parameters
serverName := "-"
needsEDNS0Padding := false
serverInfo := proxy.serversInfo.getOne()
if serverInfo != nil {
serverName = serverInfo.Name
needsEDNS0Padding = (serverInfo.Proto == stamps.StampProtoTypeDoH || serverInfo.Proto == stamps.StampProtoTypeTLS)
}
// Apply query plugins and get server info
query, serverInfo, _ := pluginsState.ApplyQueryPlugins(&proxy.pluginsGlobals, query, func() *ServerInfo {
return proxy.serversInfo.getOne()
})

// Apply query plugins
query, _ = pluginsState.ApplyQueryPlugins(&proxy.pluginsGlobals, query, needsEDNS0Padding)
if !validateQuery(query) {
return response
}
Expand Down Expand Up @@ -754,6 +748,7 @@ func (proxy *Proxy) processIncomingQuery(

// Process query with a DNS server if there's no cached response
if len(response) == 0 && serverInfo != nil {
serverName := serverInfo.Name
pluginsState.serverName = serverName

// Exchange DNS request with the server
Expand Down