Store the normalized qName in the plugin state

We now enforce the fact that a query always include a question.
It holds true for all practical use cases of dnscrypt-proxy.

This avoids quite a lot of redundant code in plugins, and is faster.

dnscrypt-proxy/dnsutils.go

@@ -2,9 +2,11 @@ package main
 
 import (
 	"encoding/binary"
+	"errors"
 	"net"
 	"strings"
 	"time"
+	"unicode/utf8"
 
 	"github.com/miekg/dns"
 )
@@ -42,7 +44,9 @@ func RefusedResponseFromMessage(srcMsg *dns.Msg, refusedCode bool, ipv4 net.IP,
 	} else {
 		dstMsg.Rcode = dns.RcodeSuccess
 		questions := srcMsg.Question
-		if len(questions) > 0 {
+		if len(questions) == 0 {
+			return dstMsg
+		}
 		question := questions[0]
 		sendHInfoResponse := true
 
@@ -73,7 +77,6 @@ func RefusedResponseFromMessage(srcMsg *dns.Msg, refusedCode bool, ipv4 net.IP,
 			dstMsg.Answer = []dns.RR{hinfo}
 		}
 	}
-	}
 	return dstMsg
 }
 
@@ -93,7 +96,7 @@ func Rcode(packet []byte) uint8 {
 	return packet[3] & 0xf
 }
 
-func NormalizeName(name *[]byte) {
+func NormalizeRawQName(name *[]byte) {
 	for i, c := range *name {
 		if c >= 65 && c <= 90 {
 			(*name)[i] = c + 32
@@ -101,11 +104,33 @@ func NormalizeName(name *[]byte) {
 	}
 }
 
-func StripTrailingDot(str string) string {
+func NormalizeQName(str string) (string, error) {
-	if len(str) > 1 && strings.HasSuffix(str, ".") {
+	if len(str) == 0 || str == "." {
-		str = str[:len(str)-1]
+		return ".", nil
 	}
-	return str
+	hasUpper := false
+	str = strings.TrimSuffix(str, ".")
+	strLen := len(str)
+	for i := 0; i < strLen; i++ {
+		c := str[i]
+		if c >= utf8.RuneSelf {
+			return str, errors.New("Query name is not an ASCII string")
+		}
+		hasUpper = hasUpper || ('A' <= c && c <= 'Z')
+	}
+	if !hasUpper {
+		return str, nil
+	}
+	var b strings.Builder
+	b.Grow(len(str))
+	for i := 0; i < strLen; i++ {
+		c := str[i]
+		if 'A' <= c && c <= 'Z' {
+			c += 'a' - 'A'
+		}
+		b.WriteByte(c)
+	}
+	return b.String(), nil
 }
 
 func getMinTTL(msg *dns.Msg, minTTL uint32, maxTTL uint32, cacheNegMinTTL uint32, cacheNegMaxTTL uint32) time.Duration {

dnscrypt-proxy/plugin_block_ip.go

@@ -122,14 +122,7 @@ func (plugin *PluginBlockIP) Eval(pluginsState *PluginsState, msg *dns.Msg) erro
 		pluginsState.action = PluginsActionReject
 		pluginsState.returnCode = PluginsReturnCodeReject
 		if plugin.logger != nil {
-			questions := msg.Question
+			qName := pluginsState.qName
-			if len(questions) != 1 {
-				return nil
-			}
-			qName := strings.ToLower(StripTrailingDot(questions[0].Name))
-			if len(qName) < 2 {
-				return nil
-			}
 			var clientIPStr string
 			if pluginsState.clientProto == "udp" {
 				clientIPStr = (*pluginsState.clientAddr).(*net.UDPAddr).IP.String()

dnscrypt-proxy/plugin_block_ipv6.go

@@ -29,11 +29,7 @@ func (plugin *PluginBlockIPv6) Reload() error {
 }
 
 func (plugin *PluginBlockIPv6) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
+	question := msg.Question[0]
-	if len(questions) != 1 {
-		return nil
-	}
-	question := questions[0]
 	if question.Qclass != dns.ClassINET || question.Qtype != dns.TypeAAAA {
 		return nil
 	}

dnscrypt-proxy/plugin_block_name.go

@@ -25,10 +25,9 @@ const aliasesLimit = 8
 var blockedNames *BlockedNames
 
 func (blockedNames *BlockedNames) check(pluginsState *PluginsState, qName string, aliasFor *string) (bool, error) {
-	qName = strings.ToLower(StripTrailingDot(qName))
 	reject, reason, xweeklyRanges := blockedNames.patternMatcher.Eval(qName)
 	if aliasFor != nil {
-		reason = reason + " (alias for [" + StripTrailingDot(*aliasFor) + "])"
+		reason = reason + " (alias for [" + *aliasFor + "])"
 	}
 	var weeklyRanges *WeeklyRanges
 	if xweeklyRanges != nil {
@@ -144,11 +143,7 @@ func (plugin *PluginBlockName) Eval(pluginsState *PluginsState, msg *dns.Msg) er
 	if blockedNames == nil || pluginsState.sessionData["whitelisted"] != nil {
 		return nil
 	}
-	questions := msg.Question
+	_, err := blockedNames.check(pluginsState, pluginsState.qName, nil)
-	if len(questions) != 1 {
-		return nil
-	}
-	_, err := blockedNames.check(pluginsState, questions[0].Name, nil)
 	return err
 }
 
@@ -181,11 +176,7 @@ func (plugin *PluginBlockNameResponse) Eval(pluginsState *PluginsState, msg *dns
 	if blockedNames == nil || pluginsState.sessionData["whitelisted"] != nil {
 		return nil
 	}
-	questions := msg.Question
+	aliasFor := pluginsState.qName
-	if len(questions) != 1 {
-		return nil
-	}
-	aliasFor := questions[0].Name
 	aliasesLeft := aliasesLimit
 	answers := msg.Answer
 	for _, answer := range answers {
@@ -193,7 +184,11 @@ func (plugin *PluginBlockNameResponse) Eval(pluginsState *PluginsState, msg *dns
 		if header.Class != dns.ClassINET || header.Rrtype != dns.TypeCNAME {
 			continue
 		}
-		if blocked, err := blockedNames.check(pluginsState, answer.(*dns.CNAME).Target, &aliasFor); blocked || err != nil {
+		target, err := NormalizeQName(answer.(*dns.CNAME).Target)
+		if err != nil {
+			return err
+		}
+		if blocked, err := blockedNames.check(pluginsState, target, &aliasFor); blocked || err != nil {
 			return err
 		}
 		aliasesLeft--

dnscrypt-proxy/plugin_block_undelegated.go

@@ -3,7 +3,6 @@ package main
 import (
 	"github.com/k-sone/critbitgo"
 	"github.com/miekg/dns"
-	"strings"
 )
 
 var undelegatedSet = []string{
@@ -179,11 +178,7 @@ func (plugin *PluginBlockUndelegated) Reload() error {
 }
 
 func (plugin *PluginBlockUndelegated) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
+	revQname := StringReverse(pluginsState.qName)
-	if len(questions) != 1 {
-		return nil
-	}
-	revQname := strings.ToLower(StringReverse(questions[0].Name))
 	match, _, found := plugin.suffixes.LongestPrefix([]byte(revQname))
 	if !found {
 		return nil

dnscrypt-proxy/plugin_block_unqualified.go

@@ -30,17 +30,11 @@ func (plugin *PluginBlockUnqualified) Reload() error {
 }
 
 func (plugin *PluginBlockUnqualified) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
+	question := msg.Question[0]
-	if len(questions) != 1 {
-		return nil
-	}
-	question := questions[0]
 	if question.Qclass != dns.ClassINET || (question.Qtype != dns.TypeA && question.Qtype != dns.TypeAAAA) {
 		return nil
 	}
-	qName := question.Name
+	if strings.IndexByte(pluginsState.qName, '.') >= 0 {
-	idx := strings.IndexByte(qName, '.')
-	if idx == -1 || (idx == 0 || idx+1 != len(qName)) {
 		return nil
 	}
 	synth := EmptyResponseFromMessage(msg)

dnscrypt-proxy/plugin_cache.go

@@ -3,7 +3,6 @@ package main
 import (
 	"crypto/sha512"
 	"encoding/binary"
-	"errors"
 	"sync"
 	"time"
 
@@ -23,12 +22,8 @@ type CachedResponses struct {
 
 var cachedResponses CachedResponses
 
-func computeCacheKey(pluginsState *PluginsState, msg *dns.Msg) ([32]byte, error) {
+func computeCacheKey(pluginsState *PluginsState, msg *dns.Msg) [32]byte {
-	questions := msg.Question
+	question := msg.Question[0]
-	if len(questions) != 1 {
-		return [32]byte{}, errors.New("No question present")
-	}
-	question := questions[0]
 	h := sha512.New512_256()
 	var tmp [5]byte
 	binary.LittleEndian.PutUint16(tmp[0:2], question.Qtype)
@@ -37,12 +32,13 @@ func computeCacheKey(pluginsState *PluginsState, msg *dns.Msg) ([32]byte, error)
 		tmp[4] = 1
 	}
 	h.Write(tmp[:])
-	normalizedName := []byte(question.Name)
+	normalizedRawQName := []byte(question.Name)
-	NormalizeName(&normalizedName)
+	NormalizeRawQName(&normalizedRawQName)
-	h.Write(normalizedName)
+	h.Write(normalizedRawQName)
 	var sum [32]byte
 	h.Sum(sum[:0])
-	return sum, nil
+
+	return sum
 }
 
 // ---
@@ -71,10 +67,7 @@ func (plugin *PluginCache) Reload() error {
 }
 
 func (plugin *PluginCache) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	cacheKey, err := computeCacheKey(pluginsState, msg)
+	cacheKey := computeCacheKey(pluginsState, msg)
-	if err != nil {
-		return nil
-	}
 	cachedResponses.RLock()
 	defer cachedResponses.RUnlock()
 	if cachedResponses.cache == nil {
@@ -134,10 +127,7 @@ func (plugin *PluginCacheResponse) Eval(pluginsState *PluginsState, msg *dns.Msg
 	if msg.Truncated {
 		return nil
 	}
-	cacheKey, err := computeCacheKey(pluginsState, msg)
+	cacheKey := computeCacheKey(pluginsState, msg)
-	if err != nil {
-		return err
-	}
 	ttl := getMinTTL(msg, pluginsState.cacheMinTTL, pluginsState.cacheMaxTTL, pluginsState.cacheNegMinTTL, pluginsState.cacheNegMaxTTL)
 	cachedResponse := CachedResponse{
 		expiration: time.Now().Add(ttl),
@@ -145,6 +135,7 @@ func (plugin *PluginCacheResponse) Eval(pluginsState *PluginsState, msg *dns.Msg
 	}
 	cachedResponses.Lock()
 	if cachedResponses.cache == nil {
+		var err error
 		cachedResponses.cache, err = lru.NewARC(pluginsState.cacheSize)
 		if err != nil {
 			cachedResponses.Unlock()

dnscrypt-proxy/plugin_cloak.go

@@ -100,21 +100,13 @@ func (plugin *PluginCloak) Reload() error {
 }
 
 func (plugin *PluginCloak) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
+	question := msg.Question[0]
-	if len(questions) != 1 {
-		return nil
-	}
-	question := questions[0]
 	if question.Qclass != dns.ClassINET || (question.Qtype != dns.TypeA && question.Qtype != dns.TypeAAAA) {
 		return nil
 	}
-	qName := strings.ToLower(StripTrailingDot(questions[0].Name))
-	if len(qName) < 2 {
-		return nil
-	}
 	now := time.Now()
 	plugin.RLock()
-	_, _, xcloakedName := plugin.patternMatcher.Eval(qName)
+	_, _, xcloakedName := plugin.patternMatcher.Eval(pluginsState.qName)
 	if xcloakedName == nil {
 		plugin.RUnlock()
 		return nil

dnscrypt-proxy/plugin_firefox.go

@@ -34,16 +34,12 @@ func (plugin *PluginFirefox) Reload() error {
 }
 
 func (plugin *PluginFirefox) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
+	question := msg.Question[0]
-	if len(questions) != 1 {
-		return nil
-	}
-	question := questions[0]
 	if question.Qclass != dns.ClassINET || (question.Qtype != dns.TypeA && question.Qtype != dns.TypeAAAA) {
 		return nil
 	}
-	qName := strings.ToLower(question.Name)
+	qName := pluginsState.qName
-	if qName != "use-application-dns.net." && !strings.HasSuffix(qName, ".use-application-dns.net.") {
+	if qName != "use-application-dns.net" && !strings.HasSuffix(qName, ".use-application-dns.net") {
 		return nil
 	}
 	synth := EmptyResponseFromMessage(msg)

dnscrypt-proxy/plugin_forward.go

@@ -71,19 +71,15 @@ func (plugin *PluginForward) Reload() error {
 }
 
 func (plugin *PluginForward) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
+	qName := pluginsState.qName
-	if len(questions) != 1 {
+	qNameLen := len(qName)
-		return nil
-	}
-	question := strings.ToLower(StripTrailingDot(questions[0].Name))
-	questionLen := len(question)
 	var servers []string
 	for _, candidate := range plugin.forwardMap {
 		candidateLen := len(candidate.domain)
-		if candidateLen > questionLen {
+		if candidateLen > qNameLen {
 			continue
 		}
-		if question[questionLen-candidateLen:] == candidate.domain && (candidateLen == questionLen || (question[questionLen-candidateLen-1] == '.')) {
+		if qName[qNameLen-candidateLen:] == candidate.domain && (candidateLen == qNameLen || (qName[qNameLen-candidateLen-1] == '.')) {
 			servers = candidate.servers
 			break
 		}

dnscrypt-proxy/plugin_nx_log.go

@@ -43,11 +43,7 @@ func (plugin *PluginNxLog) Eval(pluginsState *PluginsState, msg *dns.Msg) error
 	if msg.Rcode != dns.RcodeNameError {
 		return nil
 	}
-	questions := msg.Question
+	question := msg.Question[0]
-	if len(questions) == 0 {
-		return nil
-	}
-	question := questions[0]
 	qType, ok := dns.TypeToString[question.Qtype]
 	if !ok {
 		qType = string(qType)
@@ -58,7 +54,7 @@ func (plugin *PluginNxLog) Eval(pluginsState *PluginsState, msg *dns.Msg) error
 	} else {
 		clientIPStr = (*pluginsState.clientAddr).(*net.TCPAddr).IP.String()
 	}
-	qName := StripTrailingDot(question.Name)
+	qName := pluginsState.qName
 
 	var line string
 	if plugin.format == "tsv" {

dnscrypt-proxy/plugin_query_log.go

@@ -43,11 +43,7 @@ func (plugin *PluginQueryLog) Reload() error {
 }
 
 func (plugin *PluginQueryLog) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
+	question := msg.Question[0]
-	if len(questions) == 0 {
-		return nil
-	}
-	question := questions[0]
 	qType, ok := dns.TypeToString[question.Qtype]
 	if !ok {
 		qType = string(qType)
@@ -65,7 +61,7 @@ func (plugin *PluginQueryLog) Eval(pluginsState *PluginsState, msg *dns.Msg) err
 	} else {
 		clientIPStr = (*pluginsState.clientAddr).(*net.TCPAddr).IP.String()
 	}
-	qName := StripTrailingDot(question.Name)
+	qName := pluginsState.qName
 
 	if pluginsState.cacheHit {
 		pluginsState.serverName = "-"

dnscrypt-proxy/plugin_querymeta.go

@@ -34,10 +34,6 @@ func (plugin *PluginQueryMeta) Reload() error {
 }
 
 func (plugin *PluginQueryMeta) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
-	if len(questions) == 0 {
-		return nil
-	}
 	msg.Extra = []dns.RR{plugin.queryMetaRR}
 	return nil
 }

dnscrypt-proxy/plugin_whitelist_name.go

@@ -82,11 +82,7 @@ func (plugin *PluginWhitelistName) Reload() error {
 }
 
 func (plugin *PluginWhitelistName) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	questions := msg.Question
+	qName := pluginsState.qName
-	if len(questions) != 1 {
-		return nil
-	}
-	qName := strings.ToLower(StripTrailingDot(questions[0].Name))
 	whitelist, reason, xweeklyRanges := plugin.patternMatcher.Eval(qName)
 	var weeklyRanges *WeeklyRanges
 	if xweeklyRanges != nil {

dnscrypt-proxy/plugins.go

@@ -80,6 +80,7 @@ type PluginsState struct {
 	cacheMaxTTL                      uint32
 	rejectTTL                        uint32
 	questionMsg                      *dns.Msg
+	qName                            string
 	requestStart                     time.Time
 	requestEnd                       time.Time
 	cacheHit                         bool
@@ -235,25 +236,31 @@ func NewPluginsState(proxy *Proxy, clientProto string, clientAddr *net.Addr, sta
 		cacheMaxTTL:                      proxy.cacheMaxTTL,
 		rejectTTL:                        proxy.rejectTTL,
 		questionMsg:                      nil,
+		qName:                            "",
 		requestStart:                     start,
 		maxUnencryptedUDPSafePayloadSize: MaxDNSUDPSafePacketSize,
 	}
 }
 
 func (pluginsState *PluginsState) ApplyQueryPlugins(pluginsGlobals *PluginsGlobals, packet []byte, serverName string) ([]byte, error) {
-	if len(*pluginsGlobals.queryPlugins) == 0 && len(*pluginsGlobals.loggingPlugins) == 0 {
-		return packet, nil
-	}
 	pluginsState.serverName = serverName
 	pluginsState.action = PluginsActionForward
 	msg := dns.Msg{}
 	if err := msg.Unpack(packet); err != nil {
 		return packet, err
 	}
-	if len(msg.Question) > 1 {
+	if len(msg.Question) != 1 {
 		return packet, errors.New("Unexpected number of questions")
 	}
+	qName, err := NormalizeQName(msg.Question[0].Name)
+	if err != nil {
+		return packet, err
+	}
+	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 {
@@ -307,7 +314,6 @@ func (pluginsState *PluginsState) ApplyResponsePlugins(pluginsGlobals *PluginsGl
 		}
 		if pluginsState.action == PluginsActionReject {
 			synth := RefusedResponseFromMessage(&msg, pluginsGlobals.refusedCodeInResponses, pluginsGlobals.respondWithIPv4, pluginsGlobals.respondWithIPv6, pluginsState.rejectTTL)
-			dlog.Infof("Blocking [%s]", synth.Question[0].Name)
 			pluginsState.synthResponse = synth
 		}
 		if pluginsState.action != PluginsActionForward {
@@ -330,8 +336,8 @@ func (pluginsState *PluginsState) ApplyLoggingPlugins(pluginsGlobals *PluginsGlo
 	}
 	pluginsState.requestEnd = time.Now()
 	questionMsg := pluginsState.questionMsg
-	if questionMsg == nil || len(questionMsg.Question) > 1 {
+	if questionMsg == nil {
-		return errors.New("Unexpected number of questions")
+		return errors.New("Question not found")
 	}
 	pluginsGlobals.RLock()
 	defer pluginsGlobals.RUnlock()