Use a custom transport and a host->ip cache

maybe
Fixes #45

dnscrypt-proxy/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"crypto/rand"
 	"flag"
 	"fmt"
@@ -10,6 +11,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -21,6 +23,11 @@ import (
 
 const AppVersion = "2.0.0beta11"
 
+type CachedIPs struct {
+	sync.RWMutex
+	cache map[string]string
+}
+
 type Proxy struct {
 	proxyPublicKey               [32]byte
 	proxySecretKey               [32]byte
@@ -57,6 +64,7 @@ type Proxy struct {
 	clientsCount                 uint32
 	maxClients                   uint32
 	httpTransport                *http.Transport
+	cachedIPs                    CachedIPs
 }
 
 type App struct {
@@ -116,6 +124,7 @@ func main() {
 
 func (app *App) Start(service service.Service) error {
 	proxy := app.proxy
+	proxy.cachedIPs.cache = make(map[string]string)
 	if err := InitPluginsGlobals(&proxy.pluginsGlobals, &proxy); err != nil {
 		dlog.Fatal(err)
 	}
@@ -155,6 +164,11 @@ func (proxy *Proxy) StartProxy() {
 	for _, registeredServer := range proxy.registeredServers {
 		proxy.serversInfo.registerServer(proxy, registeredServer.name, registeredServer.stamp)
 	}
+	dialer := &net.Dialer{
+		Timeout:   proxy.timeout,
+		KeepAlive: proxy.timeout,
+		DualStack: true,
+	}
 	proxy.httpTransport = &http.Transport{
 		DisableKeepAlives:      false,
 		DisableCompression:     true,
@@ -163,6 +177,21 @@ func (proxy *Proxy) StartProxy() {
 		ResponseHeaderTimeout:  proxy.timeout,
 		ExpectContinueTimeout:  proxy.timeout,
 		MaxResponseHeaderBytes: 4096,
+		DialContext: func(ctx context.Context, network, addrStr string) (net.Conn, error) {
+			host := addrStr[:strings.LastIndex(addrStr, ":")]
+			ipOnly := host
+			proxy.cachedIPs.RLock()
+			cachedIP := proxy.cachedIPs.cache[host]
+			proxy.cachedIPs.RUnlock()
+			if len(cachedIP) > 0 {
+				ipOnly = cachedIP
+				dlog.Infof("[%s] IP address was cached: [%s]", host, ipOnly)
+			} else {
+				dlog.Infof("[%s] IP address was not cached", host)
+			}
+			addrStr = ipOnly + addrStr[strings.LastIndex(addrStr, ":"):]
+			return dialer.DialContext(ctx, network, addrStr)
+		},
 	}
 	for _, listenAddrStr := range proxy.listenAddresses {
 		listenUDPAddr, err := net.ResolveUDPAddr("udp", listenAddrStr)

dnscrypt-proxy/serversInfo.go

@@ -197,6 +197,13 @@ func (serversInfo *ServersInfo) fetchDNSCryptServerInfo(proxy *Proxy, name strin
 }
 
 func (serversInfo *ServersInfo) fetchDoHServerInfo(proxy *Proxy, name string, stamp ServerStamp) (ServerInfo, error) {
+	if len(stamp.serverAddrStr) > 0 {
+		addrStr := stamp.serverAddrStr
+		ipOnly := addrStr[:strings.LastIndex(addrStr, ":")]
+		proxy.cachedIPs.Lock()
+		proxy.cachedIPs.cache[stamp.providerName] = ipOnly
+		proxy.cachedIPs.Unlock()
+	}
 	url := &url.URL{
 		Scheme: "https",
 		Host:   stamp.providerName,

dnscrypt-proxy/stamps.go

@@ -70,7 +70,7 @@ func NewServerStampFromString(stampStr string) (ServerStamp, error) {
 // id(u8)=0x02 props addrLen(1) serverAddr pkStrlen(1) pkStr providerNameLen(1) providerName
 
 func newDNSCryptServerStamp(bin []byte) (ServerStamp, error) {
-	stamp := ServerStamp{proto:StampProtoTypeDNSCrypt}
+	stamp := ServerStamp{proto: StampProtoTypeDNSCrypt}
 	if len(bin) < 24 {
 		return stamp, errors.New("Stamp is too short")
 	}
@@ -85,6 +85,9 @@ func newDNSCryptServerStamp(bin []byte) (ServerStamp, error) {
 	pos++
 	stamp.serverAddrStr = string(bin[pos : pos+len])
 	pos += len
+	if net.ParseIP(stamp.serverAddrStr) != nil {
+		stamp.serverAddrStr = fmt.Sprintf("%s:%d", stamp.serverAddrStr, DefaultPort)
+	}
 
 	len = int(bin[pos])
 	if len >= binLen-pos {
@@ -111,7 +114,7 @@ func newDNSCryptServerStamp(bin []byte) (ServerStamp, error) {
 // id(u8)=0x02 props addrLen(1) serverAddr hashLen(1) hash providerNameLen(1) providerName pathLen(1) path
 
 func newDoHServerStamp(bin []byte) (ServerStamp, error) {
-	stamp := ServerStamp{proto:StampProtoTypeDoH}
+	stamp := ServerStamp{proto: StampProtoTypeDoH}
 
 	stamp.props = ServerInformalProperties(binary.LittleEndian.Uint64(bin[1:9]))
 	binLen := len(bin)
@@ -124,6 +127,9 @@ func newDoHServerStamp(bin []byte) (ServerStamp, error) {
 	pos++
 	stamp.serverAddrStr = string(bin[pos : pos+len])
 	pos += len
+	if net.ParseIP(stamp.serverAddrStr) != nil {
+		stamp.serverAddrStr = fmt.Sprintf("%s:%d", stamp.serverAddrStr, DefaultPort)
+	}
 
 	len = int(bin[pos])
 	if len >= binLen-pos {