Initial support for DNS-over-HTTP2 -- Yes, it works with Google.

dnscrypt-proxy/dnscrypt-proxy.toml

@@ -14,7 +14,7 @@
 ## List of servers to use
 ## If this line is commented, all registered servers will be used
 
-# server_names = ['scaleway-fr']
+server_names = ['google']
 
 
 ## List of local addresses and ports to listen to. Can be IPv4 and/or IPv6.
@@ -258,6 +258,6 @@ format = 'tsv'
 ## Optional, local, static list of additional servers
 ## Mostly useful for testing your own servers.
 
-# [static]
-#   [static.'example.com']
-#   stamp = 'sdns://AQMAAAAAAAAAEjIxMi40Ny4yMjguMTM2OjQ0MyDoAbhOpga_sLrAzkNEW7FeumSwL6PEqjGuEGNqB5AyTR8yLmRuc2NyeXB0LWNlcnQuZnIuZG5zY3J5cHQub3Jn'
+ [static]
+   [static.'google']
+   stamp = 'sdns://AgAAAAAAAAAADjIxNi41OC4yMDQuMTQyAA5kbnMuZ29vZ2xlLmNvbQ0vZXhwZXJpbWVudGFs'

dnscrypt-proxy/main.go

@@ -1,10 +1,13 @@
 package main
 
 import (
+	"bytes"
 	"crypto/rand"
 	"flag"
 	"fmt"
+	"io/ioutil"
 	"net"
+	"net/http"
 	"os"
 	"path/filepath"
 	"sync"
@@ -53,6 +56,7 @@ type Proxy struct {
 	urlsToPrefetch               []URLToPrefetch
 	clientsCount                 uint32
 	maxClients                   uint32
+	httpTransport                *http.Transport
 }
 
 type App struct {
@@ -151,6 +155,15 @@ func (proxy *Proxy) StartProxy() {
 	for _, registeredServer := range proxy.registeredServers {
 		proxy.serversInfo.registerServer(proxy, registeredServer.name, registeredServer.stamp)
 	}
+	proxy.httpTransport = &http.Transport{
+		DisableKeepAlives:      false,
+		DisableCompression:     true,
+		MaxIdleConns:           1,
+		IdleConnTimeout:        proxy.timeout,
+		ResponseHeaderTimeout:  proxy.timeout,
+		ExpectContinueTimeout:  proxy.timeout,
+		MaxResponseHeaderBytes: 4096,
+	}
 	for _, listenAddrStr := range proxy.listenAddresses {
 		listenUDPAddr, err := net.ResolveUDPAddr("udp", listenAddrStr)
 		if err != nil {
@@ -353,6 +366,7 @@ func (proxy *Proxy) processIncomingQuery(serverInfo *ServerInfo, clientProto str
 		}
 	}
 	if len(response) == 0 {
+		if serverInfo.Proto == StampProtoTypeDNSCrypt {
 			encryptedQuery, clientNonce, err := proxy.Encrypt(serverInfo, query, serverProto)
 			if err != nil {
 				return
@@ -367,8 +381,46 @@ func (proxy *Proxy) processIncomingQuery(serverInfo *ServerInfo, clientProto str
 				serverInfo.noticeFailure(proxy)
 				return
 			}
+		} else if serverInfo.Proto == StampProtoTypeDoH {
+			req := &http.Request{
+				Method: "POST",
+				URL:    serverInfo.URL,
+				Host:   serverInfo.HostName,
+				Header: map[string][]string{
+					"Accept":       {"application/dns-udpwireformat"},
+					"Content-Type": {"application/dns-udpwireformat"},
+					"User-Agent":   {"dnscrypt-proxy"},
+				},
+				Close: false,
+				Body:  ioutil.NopCloser(bytes.NewReader(query)),
+			}
+			client := http.Client{
+				Transport: proxy.httpTransport,
+				Timeout:   proxy.timeout,
+			}
+			resp, err := client.Do(req)
+			if err == nil && resp != nil && (resp.StatusCode < 200 || resp.StatusCode > 299) {
+				return
+			} else if err != nil || resp == nil {
+				return
+			}
+			response, err = ioutil.ReadAll(resp.Body)
+			if err != nil {
+				return
+			}
+		} else {
+			dlog.Fatal("Unsupported protocol")
+		}
+		if err != nil {
+			serverInfo.noticeFailure(proxy)
+			return
+		}
 		response, _ = pluginsState.ApplyResponsePlugins(&proxy.pluginsGlobals, response)
 	}
+	if len(response) < MinDNSPacketSize || len(response) > MaxDNSPacketSize {
+		serverInfo.noticeFailure(proxy)
+		return
+	}
 	if clientProto == "udp" {
 		if len(response) > MaxDNSUDPPacketSize {
 			response, err = TruncatedResponse(response)

dnscrypt-proxy/serversInfo.go

@@ -1,9 +1,15 @@
 package main
 
 import (
+	"bytes"
 	"encoding/hex"
+	"errors"
+	"fmt"
+	"io/ioutil"
 	"math/rand"
 	"net"
+	"net/http"
+	"net/url"
 	"strings"
 	"sync"
 	"time"
@@ -32,12 +38,15 @@ type RegisteredServer struct {
 
 type ServerInfo struct {
 	sync.RWMutex
+	Proto              StampProtoType
 	MagicQuery         [8]byte
 	ServerPk           [32]byte
 	SharedKey          [32]byte
 	CryptoConstruction CryptoConstruction
 	Name               string
 	Timeout            time.Duration
+	URL                *url.URL
+	HostName           string
 	UDPAddr            *net.UDPAddr
 	TCPAddr            *net.TCPAddr
 	lastActionTS       time.Time
@@ -142,6 +151,15 @@ func (serversInfo *ServersInfo) getOne() *ServerInfo {
 }
 
 func (serversInfo *ServersInfo) fetchServerInfo(proxy *Proxy, name string, stamp ServerStamp) (ServerInfo, error) {
+	if stamp.proto == StampProtoTypeDNSCrypt {
+		return serversInfo.fetchDNSCryptServerInfo(proxy, name, stamp)
+	} else if stamp.proto == StampProtoTypeDoH {
+		return serversInfo.fetchDoHServerInfo(proxy, name, stamp)
+	}
+	return ServerInfo{}, errors.New("Unsupported protocol")
+}
+
+func (serversInfo *ServersInfo) fetchDNSCryptServerInfo(proxy *Proxy, name string, stamp ServerStamp) (ServerInfo, error) {
 	if len(stamp.serverPk) != ed25519.PublicKeySize {
 		serverPk, err := hex.DecodeString(strings.Replace(string(stamp.serverPk), ":", "", -1))
 		if err != nil || len(serverPk) != ed25519.PublicKeySize {
@@ -163,6 +181,7 @@ func (serversInfo *ServersInfo) fetchServerInfo(proxy *Proxy, name string, stamp
 		return ServerInfo{}, err
 	}
 	serverInfo := ServerInfo{
+		Proto:              StampProtoTypeDNSCrypt,
 		MagicQuery:         certInfo.MagicQuery,
 		ServerPk:           certInfo.ServerPk,
 		SharedKey:          certInfo.SharedKey,
@@ -176,6 +195,59 @@ func (serversInfo *ServersInfo) fetchServerInfo(proxy *Proxy, name string, stamp
 	return serverInfo, nil
 }
 
+func (serversInfo *ServersInfo) fetchDoHServerInfo(proxy *Proxy, name string, stamp ServerStamp) (ServerInfo, error) {
+	url := &url.URL{
+		Scheme: "https",
+		Host:   stamp.providerName,
+		Path:   stamp.path,
+	}
+	body := ioutil.NopCloser(bytes.NewReader([]byte{
+		0x00, 0x00, 0x01, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01,
+	}))
+	req := &http.Request{
+		Method: "POST",
+		URL:    url,
+		Header: map[string][]string{
+			"Accept":       {"application/dns-udpwireformat"},
+			"Content-Type": {"application/dns-udpwireformat"},
+			"User-Agent":   {"dnscrypt-proxy"},
+		},
+		Close: false,
+		Host:  stamp.providerName,
+		Body:  body,
+	}
+	client := http.Client{
+		Transport: proxy.httpTransport,
+		Timeout:   proxy.timeout,
+	}
+	start := time.Now()
+	resp, err := client.Do(req)
+	elapsed := time.Since(start)
+	if err == nil && resp != nil && (resp.StatusCode < 200 || resp.StatusCode > 299) {
+		return ServerInfo{}, fmt.Errorf("Webserver returned code %d", resp.StatusCode)
+	} else if err != nil {
+		return ServerInfo{}, err
+	} else if resp == nil {
+		return ServerInfo{}, errors.New("Webserver returned an error")
+	}
+	respBody, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return ServerInfo{}, err
+	}
+	if len(respBody) < MinDNSPacketSize || len(respBody) > MaxDNSPacketSize {
+		return ServerInfo{}, errors.New("Webserver returned an unexpected response")
+	}
+	serverInfo := ServerInfo{
+		Proto:      StampProtoTypeDoH,
+		Name:       name,
+		Timeout:    proxy.timeout,
+		URL:        url,
+		HostName:   stamp.providerName,
+		initialRtt: int(elapsed.Nanoseconds() / 1000000),
+	}
+	return serverInfo, nil
+}
+
 func (serverInfo *ServerInfo) noticeFailure(proxy *Proxy) {
 	serverInfo.Lock()
 	serverInfo.rtt.Set(float64(proxy.timeout.Nanoseconds()))