mirror of
https://github.com/DNSCrypt/dnscrypt-proxy.git
synced 2024-12-25 00:00:55 +01:00
Start implementing a basic cache
This commit is contained in:
parent
da3e3e61b4
commit
77cdc1db78
@ -14,10 +14,11 @@ type Config struct {
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ServerNames []string `toml:"server_names"`
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ListenAddresses []string `toml:"listen_addresses"`
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Daemonize bool
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ForceTCP bool `toml:"force_tcp"`
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Timeout int `toml:"timeout_ms"`
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CertRefreshDelay int `toml:"cert_refresh_delay"`
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BlockIPv6 bool `toml:"block_ipv6"`
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ForceTCP bool `toml:"force_tcp"`
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Timeout int `toml:"timeout_ms"`
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CertRefreshDelay int `toml:"cert_refresh_delay"`
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BlockIPv6 bool `toml:"block_ipv6"`
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Cache bool
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ServersConfig map[string]ServerConfig `toml:"servers"`
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}
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@ -58,6 +59,10 @@ func ConfigLoad(proxy *Proxy, config_file string) error {
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proxy.listenAddresses = config.ListenAddresses
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proxy.daemonize = config.Daemonize
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proxy.pluginBlockIPv6 = config.BlockIPv6
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proxy.cache = config.Cache
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proxy.negCacheMinTTL = 60
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proxy.minTTL = 60
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proxy.maxTTL = 86400
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if len(config.ServerNames) == 0 {
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for serverName := range config.ServersConfig {
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config.ServerNames = append(config.ServerNames, serverName)
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@ -48,6 +48,13 @@ cert_refresh_delay = 30
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block_ipv6 = false
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############## DNS Cache ##############
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## Enable a basic DNS cache to reduce outgoing traffic
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cache = true
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############## Servers ##############
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## Static list of available servers
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@ -1,6 +1,8 @@
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package main
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import (
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"time"
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"github.com/miekg/dns"
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)
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@ -30,3 +32,27 @@ func EmptyResponseFromMessage(srcMsg *dns.Msg) (*dns.Msg, error) {
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func HasTCFlag(packet []byte) bool {
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return packet[2]&2 == 2
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}
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func NormalizeName(name *[]byte) {
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for i, c := range *name {
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if c >= 65 && c <= 90 {
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(*name)[i] = c + 32
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}
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}
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}
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func getMinTTL(msg *dns.Msg, minTTL uint32, maxTTL uint32, negCacheMinTTL uint32) time.Duration {
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if len(msg.Answer) <= 0 {
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return time.Duration(negCacheMinTTL) * time.Second
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}
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ttl := uint32(maxTTL)
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for _, rr := range msg.Answer {
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if rr.Header().Ttl < ttl {
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ttl = rr.Header().Ttl
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}
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}
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if ttl < minTTL {
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ttl = minTTL
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}
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return time.Duration(ttl) * time.Second
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}
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@ -24,6 +24,10 @@ type Proxy struct {
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daemonize bool
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registeredServers []RegisteredServer
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pluginBlockIPv6 bool
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cache bool
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negCacheMinTTL uint32
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minTTL uint32
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maxTTL uint32
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}
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func main() {
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@ -191,6 +195,7 @@ func (proxy *Proxy) processIncomingQuery(serverInfo *ServerInfo, serverProto str
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serverInfo.noticeFailure(proxy)
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return
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}
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response, _ = pluginsState.ApplyResponsePlugins(response)
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}
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if clientAddr != nil {
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if len(response) > MaxDNSUDPPacketSize {
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@ -1,6 +1,13 @@
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package main
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import (
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"crypto/sha512"
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"encoding/binary"
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"errors"
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"math/rand"
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"sync"
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"time"
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"github.com/miekg/dns"
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)
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@ -23,6 +30,7 @@ type PluginsState struct {
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queryPlugins *[]Plugin
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responsePlugins *[]Plugin
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synthResponse *dns.Msg
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dnssec bool
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}
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type Plugin interface {
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@ -39,12 +47,25 @@ func NewPluginsState(proxy *Proxy, proto string) PluginsState {
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*queryPlugins = append(*queryPlugins, Plugin(new(PluginGetSetPayloadSize)))
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responsePlugins := &[]Plugin{}
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if proxy.cache {
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*responsePlugins = append(*responsePlugins, Plugin(new(PluginCache)))
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}
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return PluginsState{action: PluginsActionForward, maxPayloadSize: MaxDNSUDPPacketSize - ResponseOverhead,
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queryPlugins: queryPlugins, responsePlugins: responsePlugins, proto: proto}
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return PluginsState{
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action: PluginsActionForward,
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maxPayloadSize: MaxDNSUDPPacketSize - ResponseOverhead,
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queryPlugins: queryPlugins,
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responsePlugins: responsePlugins,
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proto: proto,
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}
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}
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// ---------------- Query plugins ----------------
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func (pluginsState *PluginsState) ApplyQueryPlugins(packet []byte) ([]byte, error) {
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if len(*pluginsState.queryPlugins) == 0 {
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return packet, nil
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}
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pluginsState.action = PluginsActionForward
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msg := dns.Msg{}
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if err := msg.Unpack(packet); err != nil {
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@ -86,6 +107,7 @@ func (plugin *PluginGetSetPayloadSize) Eval(pluginsState *PluginsState, msg *dns
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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.dnssec = dnssec
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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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@ -129,3 +151,108 @@ func (plugin *PluginBlockIPv6) Eval(pluginsState *PluginsState, msg *dns.Msg) er
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pluginsState.action = PluginsActionSynth
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return nil
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}
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// ---------------- Response plugins ----------------
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func (pluginsState *PluginsState) ApplyResponsePlugins(packet []byte) ([]byte, error) {
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if len(*pluginsState.responsePlugins) == 0 {
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return packet, nil
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}
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pluginsState.action = PluginsActionForward
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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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for _, plugin := range *pluginsState.responsePlugins {
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if ret := plugin.Eval(pluginsState, &msg); ret != nil {
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pluginsState.action = PluginsActionDrop
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return packet, ret
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}
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if pluginsState.action != PluginsActionForward {
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break
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}
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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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// -------- cache plugin --------
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type CachedResponse struct {
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expiration time.Time
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msg dns.Msg
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}
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type CachedResponses struct {
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sync.RWMutex
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cache map[[32]byte]CachedResponse
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}
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var cachedResponses CachedResponses
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type PluginCache struct {
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cachedResponses *CachedResponses
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}
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func (plugin *PluginCache) Name() string {
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return "cache"
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}
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func (plugin *PluginCache) Description() string {
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return "DNS cache."
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}
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func (plugin *PluginCache) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
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plugin.cachedResponses = &cachedResponses
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cacheKey, err := computeCacheKey(pluginsState, msg)
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if err != nil {
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return nil
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}
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ttl := getMinTTL(msg, 60, 86400, 60)
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cachedResponse := CachedResponse{
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expiration: time.Now().Add(ttl),
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msg: *msg,
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}
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plugin.cachedResponses.Lock()
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defer plugin.cachedResponses.Unlock()
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if plugin.cachedResponses.cache == nil {
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plugin.cachedResponses.cache = make(map[[32]byte]CachedResponse)
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}
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if len(plugin.cachedResponses.cache) > 1000 {
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z := byte(rand.Uint32())
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for k := range plugin.cachedResponses.cache {
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delete(plugin.cachedResponses.cache, k)
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if k[0] == z {
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break
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}
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}
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}
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plugin.cachedResponses.cache[cacheKey] = cachedResponse
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return nil
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}
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func computeCacheKey(pluginsState *PluginsState, msg *dns.Msg) ([32]byte, error) {
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questions := msg.Question
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if len(questions) != 1 {
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return [32]byte{}, errors.New("No question present")
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}
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question := questions[0]
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h := sha512.New512_256()
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var tmp [5]byte
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binary.LittleEndian.PutUint16(tmp[0:2], question.Qtype)
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binary.LittleEndian.PutUint16(tmp[2:4], question.Qclass)
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if pluginsState.dnssec {
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tmp[4] = 1
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}
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h.Write(tmp[:])
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normalizedName := []byte(question.Name)
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NormalizeName(&normalizedName)
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h.Write(normalizedName)
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var sum [32]byte
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h.Sum(sum[:])
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return sum, nil
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}
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