fix relative path

* Add local_addr configuration for doh-server

This commit adds a `local_addr` string value to `doh-server.conf`, specifying the IP address and port from which outgoing calls to upstream DNS resolvers should originate. This value is set as the `udpClient`'s and `tcpClient`'s `Dialer.LocalAddr` when initializing a `NewServer`. If the value is left empty in `doh-server.conf`, it defaults to the first `listen` address (which in turn defaults to `"127.0.0.1:8053"`).

One use case for this would be if `doh-server` is proxying requests to a local DNS resolver (e.g. `unbound` or Pi-hole). Up to version 2.0.0, all DNS queries from `doh-server` are sent from `127.0.0.1` (even if the `listen` address is set to a different loopback IP address), making it hard to distinguish them from all other local DNS queries from the same machine in the query logs.

* Revert defaulting of local_addr to listen address

This commit reverts to the existing behavior when `conf.LocalAddr == ""`, i.e. letting `dns.Client` instantiate its own `Dialer` with the default local address.

* Fixup comment in configuration file

* Log errors from Dialer instantiation (e.g. if LocalAddr port is missing)

* Fixup other comment in configuration file

* Return error and log fatal

.gitignore

@@ -3,6 +3,7 @@
 *.dll
 *.so
 *.dylib
+build/
 
 # Test binary, build with `go test -c`
 *.test
@@ -12,3 +13,5 @@
 
 # Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736
 .glide/
+
+.idea/

Changelog.md

@@ -4,6 +4,17 @@ This Changelog records major changes between versions.
 
 Not all changes are recorded. Please check git log for details.
 
+## Version 2.0.1
+
+- Fix a crash with the random load balancing algorithm.
+
+## Version 2.0.0
+
+**This is a breaking change!** Please update the configuration file after upgrading.
+
+- Implemented two upstream server selector algorithms: `weighted_round_robin` and `lvs_weighted_round_robin`.
+- Add a configuration option for doh-server: `log_guessed_client_ip`.
+
 ## Version 1.4.2
 
 - Add PID file feature for systems which lacks a cgroup-based process tracker.

Makefile

@@ -62,7 +62,7 @@ deps:
 	$(GOGET_UPDATE) github.com/m13253/dns-over-https/json-dns
 	$(GOGET) ./doh-client ./doh-server
 
-doh-client/doh-client: deps doh-client/client.go doh-client/config.go doh-client/google.go doh-client/ietf.go doh-client/main.go doh-client/version.go json-dns/error.go json-dns/globalip.go json-dns/marshal.go json-dns/response.go json-dns/unmarshal.go
+doh-client/doh-client: deps doh-client/client.go doh-client/config/config.go doh-client/google.go doh-client/ietf.go doh-client/main.go doh-client/version.go json-dns/error.go json-dns/globalip.go json-dns/marshal.go json-dns/response.go json-dns/unmarshal.go
 	cd doh-client && $(GOBUILD)
 
 doh-server/doh-server: deps doh-server/config.go doh-server/google.go doh-server/ietf.go doh-server/main.go doh-server/server.go doh-server/version.go json-dns/error.go json-dns/globalip.go json-dns/marshal.go json-dns/response.go json-dns/unmarshal.go

contrib/package.sh

@@ -0,0 +1,173 @@
+#!/bin/bash 
+set -euo pipefail
+
+# This is a script used for automated packaging.
+# Debian maintainers please don't use this.
+# 
+# Environment assumption:
+#  * Ubuntu 16.04
+#  * run with normal user
+#  * sudo with no password
+#  * go and fpm is pre-installed
+#  * rpmbuild is required if you need rpm packages
+#
+# Compatible with Azure DevOps hosted Ubuntu 16.04 agent
+
+export DEBIAN_FRONTEND="noninteractive"
+export DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"/..
+export BUILD_BINARIESDIRECTORY="${BUILD_BINARIESDIRECTORY:-${DIR}/build/bin}"
+export BUILD_ARTIFACTSTAGINGDIRECTORY="${BUILD_ARTIFACTSTAGINGDIRECTORY:-${DIR}/build/packages}"
+export TMP_DIRECTORY="/tmp/dohbuild"
+export GOPATH="${GOPATH:-/tmp/go}"
+export GOBIN="${GOBIN:-/tmp/go/bin}"
+
+function prepare_env() {
+    echo "Checking dependencies"
+
+    if ! [ -x "$(command -v go)" ]; then
+        echo "Please install golang"
+        exit 1
+    fi
+
+    if [ -x "$(command -v apt-get)" ]; then
+        sudo apt-get -y update
+    fi
+
+    if ! [ -x "$(command -v rpmbuild)" ]; then
+        # TODO: correctly install rpmbuild
+        ! sudo apt-get -y install rpmbuild
+    fi
+
+    # if ! [ -x "$(command -v upx)" ]; then
+    #     sudo apt-get -y install upx
+    # fi
+
+    echo "Creating directories"
+
+    mkdir -p "${BUILD_BINARIESDIRECTORY}/nm-dispatcher"
+    mkdir -p "${BUILD_BINARIESDIRECTORY}/launchd"
+    mkdir -p "${BUILD_BINARIESDIRECTORY}/systemd"
+    mkdir -p "${BUILD_BINARIESDIRECTORY}/config"
+    mkdir -p "${BUILD_ARTIFACTSTAGINGDIRECTORY}"
+    mkdir -p "${TMP_DIRECTORY}"
+}
+
+function build_common() {
+    cp NetworkManager/dispatcher.d/* "${BUILD_BINARIESDIRECTORY}"/nm-dispatcher
+    cp launchd/*.plist "${BUILD_BINARIESDIRECTORY}"/launchd
+    cp systemd/*.service "${BUILD_BINARIESDIRECTORY}"/systemd
+    cp doh-server/doh-server.conf "${BUILD_BINARIESDIRECTORY}"/config
+    cp doh-client/doh-client.conf "${BUILD_BINARIESDIRECTORY}"/config
+}
+
+# used to get version
+function build_native() {
+    echo "Building a native binary..."
+
+    go build -ldflags="-s -w" -o ${BUILD_BINARIESDIRECTORY}/"${EXE}"-native
+}
+
+function build() {
+    echo "Building ${EXE} for OS=$1 ARCH=$2"
+    env GOOS="$1" GOARCH="$2" go build -ldflags="-s -w" -o ${BUILD_BINARIESDIRECTORY}/"${EXE}"-"$3"
+
+    # echo "Compressing executable"
+    # ! upx --ultra-brute ${BUILD_BINARIESDIRECTORY}/${EXE}-"$3" || true
+}
+
+function package() {
+    VERSION=$("${BUILD_BINARIESDIRECTORY}/${EXE}-native" --version | head -n 1 | cut -d" " -f2)
+    REVISION=$(git log --pretty=format:'%h' -n 1)
+
+    echo "Packaging ${EXE} ${VERSION} for OS=$1 ARCH=$2 TYPE=$3 DST=$4"
+
+    ! rm -rf "${TMP_DIRECTORY}"/*
+
+    mkdir -p "${TMP_DIRECTORY}"/usr/bin
+    cp "${BUILD_BINARIESDIRECTORY}"/"${EXE}"-"$3" "${TMP_DIRECTORY}"/usr/bin/"${EXE}"
+
+    mkdir -p "${TMP_DIRECTORY}"/usr/lib/systemd/system
+    cp "${BUILD_BINARIESDIRECTORY}"/systemd/"${EXE}".service "${TMP_DIRECTORY}"/usr/lib/systemd/system
+
+    mkdir -p "${TMP_DIRECTORY}"/etc/dns-over-https
+    cp "${BUILD_BINARIESDIRECTORY}"/config/"${EXE}".conf "${TMP_DIRECTORY}"/etc/dns-over-https
+
+    mkdir -p "${TMP_DIRECTORY}"/etc/NetworkManager/dispatcher.d
+    cp "${BUILD_BINARIESDIRECTORY}"/nm-dispatcher/"${EXE}" "${TMP_DIRECTORY}"/etc/NetworkManager/dispatcher.d
+
+    # call fpm
+    fpm --input-type dir \
+        --output-type $4 \
+        --chdir "${TMP_DIRECTORY}" \
+        --package "${BUILD_ARTIFACTSTAGINGDIRECTORY}" \
+        --name "${EXE}" \
+        --description "${DESCR}" \
+        --version "${VERSION}" \
+        --iteration "${REVISION}" \
+        --url "https://github.com/m13253/dns-over-https" \
+        --vendor "Star Brilliant <coder@poorlab.com>" \
+        --license "MIT License" \
+        --category "net" \
+        --maintainer "James Swineson <autopkg@public.swineson.me>" \
+        --architecture "$2" \
+        --force \
+        .
+}
+
+cd "${DIR}"/..
+prepare_env
+make deps
+build_common
+
+pushd doh-server
+export EXE="doh-server"
+export DESCR="DNS-over-HTTPS Server"
+
+build_native
+
+build linux amd64 linux-amd64
+package linux amd64 linux-amd64 deb
+! package linux amd64 linux-amd64 rpm
+package linux amd64 linux-amd64 pacman
+
+build linux arm linux-armhf
+package linux arm linux-armhf deb
+! package linux arm linux-armhf rpm
+package linux arm linux-armhf pacman
+
+build linux arm64 linux-arm64
+package linux arm64 linux-arm64 deb
+! package linux arm64 linux-arm64 rpm
+package linux arm64 linux-arm64 pacman
+
+# build darwin amd64 darwin-amd64
+# build windows 386 windows-x86.exe
+# build windows amd64 windows-amd64.exe
+popd
+
+pushd doh-client
+export EXE="doh-client"
+export DESCR="DNS-over-HTTPS Client"
+
+build_native
+
+build linux amd64 linux-amd64
+package linux amd64 linux-amd64 deb
+! package linux amd64 linux-amd64 rpm
+package linux amd64 linux-amd64 pacman
+
+build linux arm linux-armhf
+package linux arm linux-armhf deb
+! package linux arm linux-armhf rpm
+package linux arm linux-armhf pacman
+
+build linux arm64 linux-arm64
+package linux arm64 linux-arm64 deb
+! package linux arm64 linux-arm64 rpm
+package linux arm64 linux-arm64 pacman
+
+# build darwin amd64 darwin-amd64
+# build windows 386 windows-x86.exe
+# build windows amd64 windows-amd64.exe
+popd
+

doh-client/client.go

@@ -31,11 +31,14 @@ import (
 	"net"
 	"net/http"
 	"net/http/cookiejar"
+	"net/url"
 	"strconv"
 	"strings"
 	"sync"
 	"time"
 
+	"github.com/m13253/dns-over-https/doh-client/config"
+	"github.com/m13253/dns-over-https/doh-client/selector"
 	"github.com/m13253/dns-over-https/json-dns"
 	"github.com/miekg/dns"
 	"golang.org/x/net/http2"
@@ -43,7 +46,7 @@ import (
 )
 
 type Client struct {
-	conf                 *config
+	conf                 *config.Config
 	bootstrap            []string
 	passthrough          []string
 	udpClient            *dns.Client
@@ -56,6 +59,7 @@ type Client struct {
 	httpTransport        *http.Transport
 	httpClient           *http.Client
 	httpClientLastCreate time.Time
+	selector             selector.Selector
 }
 
 type DNSRequest struct {
@@ -68,7 +72,7 @@ type DNSRequest struct {
 	err               error
 }
 
-func NewClient(conf *config) (c *Client, err error) {
+func NewClient(conf *config.Config) (c *Client, err error) {
 	c = &Client{
 		conf: conf,
 	}
@@ -78,11 +82,11 @@ func NewClient(conf *config) (c *Client, err error) {
 	c.udpClient = &dns.Client{
 		Net:     "udp",
 		UDPSize: dns.DefaultMsgSize,
-		Timeout: time.Duration(conf.Timeout) * time.Second,
+		Timeout: time.Duration(conf.Other.Timeout) * time.Second,
 	}
 	c.tcpClient = &dns.Client{
 		Net:     "tcp",
-		Timeout: time.Duration(conf.Timeout) * time.Second,
+		Timeout: time.Duration(conf.Other.Timeout) * time.Second,
 	}
 	for _, addr := range conf.Listen {
 		c.udpServers = append(c.udpServers, &dns.Server{
@@ -98,9 +102,9 @@ func NewClient(conf *config) (c *Client, err error) {
 		})
 	}
 	c.bootstrapResolver = net.DefaultResolver
-	if len(conf.Bootstrap) != 0 {
-		c.bootstrap = make([]string, len(conf.Bootstrap))
-		for i, bootstrap := range conf.Bootstrap {
+	if len(conf.Other.Bootstrap) != 0 {
+		c.bootstrap = make([]string, len(conf.Other.Bootstrap))
+		for i, bootstrap := range conf.Other.Bootstrap {
 			bootstrapAddr, err := net.ResolveUDPAddr("udp", bootstrap)
 			if err != nil {
 				bootstrapAddr, err = net.ResolveUDPAddr("udp", "["+bootstrap+"]:53")
@@ -120,9 +124,9 @@ func NewClient(conf *config) (c *Client, err error) {
 				return conn, err
 			},
 		}
-		if len(conf.Passthrough) != 0 {
-			c.passthrough = make([]string, len(conf.Passthrough))
-			for i, passthrough := range conf.Passthrough {
+		if len(conf.Other.Passthrough) != 0 {
+			c.passthrough = make([]string, len(conf.Other.Passthrough))
+			for i, passthrough := range conf.Other.Passthrough {
 				if punycode, err := idna.ToASCII(passthrough); err != nil {
 					passthrough = punycode
 				}
@@ -133,7 +137,7 @@ func NewClient(conf *config) (c *Client, err error) {
 	// Most CDNs require Cookie support to prevent DDoS attack.
 	// Disabling Cookie does not effectively prevent tracking,
 	// so I will leave it on to make anti-DDoS services happy.
-	if !c.conf.NoCookies {
+	if !c.conf.Other.NoCookies {
 		c.cookieJar, err = cookiejar.New(nil)
 		if err != nil {
 			return nil, err
@@ -147,23 +151,93 @@ func NewClient(conf *config) (c *Client, err error) {
 	if err != nil {
 		return nil, err
 	}
+
+	switch c.conf.Upstream.UpstreamSelector {
+	case config.NginxWRR:
+		if c.conf.Other.Verbose {
+			log.Println(config.NginxWRR, "mode start")
+		}
+
+		s := selector.NewNginxWRRSelector(time.Duration(c.conf.Other.Timeout) * time.Second)
+		for _, u := range c.conf.Upstream.UpstreamGoogle {
+			if err := s.Add(u.URL, selector.Google, u.Weight); err != nil {
+				return nil, err
+			}
+		}
+
+		for _, u := range c.conf.Upstream.UpstreamIETF {
+			if err := s.Add(u.URL, selector.IETF, u.Weight); err != nil {
+				return nil, err
+			}
+		}
+
+		c.selector = s
+
+	case config.LVSWRR:
+		if c.conf.Other.Verbose {
+			log.Println(config.LVSWRR, "mode start")
+		}
+
+		s := selector.NewLVSWRRSelector(time.Duration(c.conf.Other.Timeout) * time.Second)
+		for _, u := range c.conf.Upstream.UpstreamGoogle {
+			if err := s.Add(u.URL, selector.Google, u.Weight); err != nil {
+				return nil, err
+			}
+		}
+
+		for _, u := range c.conf.Upstream.UpstreamIETF {
+			if err := s.Add(u.URL, selector.IETF, u.Weight); err != nil {
+				return nil, err
+			}
+		}
+
+		c.selector = s
+
+	default:
+		if c.conf.Other.Verbose {
+			log.Println(config.Random, "mode start")
+		}
+
+		// if selector is invalid or random, use random selector, or should we stop program and let user knows he is wrong?
+		s := selector.NewRandomSelector()
+		for _, u := range c.conf.Upstream.UpstreamGoogle {
+			if err := s.Add(u.URL, selector.Google); err != nil {
+				return nil, err
+			}
+		}
+
+		for _, u := range c.conf.Upstream.UpstreamIETF {
+			if err := s.Add(u.URL, selector.IETF); err != nil {
+				return nil, err
+			}
+		}
+
+		c.selector = s
+	}
+
+	if c.conf.Other.Verbose {
+		if reporter, ok := c.selector.(selector.DebugReporter); ok {
+			reporter.ReportWeights()
+		}
+	}
+
 	return c, nil
 }
 
 func (c *Client) newHTTPClient() error {
 	c.httpClientMux.Lock()
 	defer c.httpClientMux.Unlock()
-	if !c.httpClientLastCreate.IsZero() && time.Since(c.httpClientLastCreate) < time.Duration(c.conf.Timeout)*time.Second {
+	if !c.httpClientLastCreate.IsZero() && time.Since(c.httpClientLastCreate) < time.Duration(c.conf.Other.Timeout)*time.Second {
 		return nil
 	}
 	if c.httpTransport != nil {
 		c.httpTransport.CloseIdleConnections()
 	}
 	dialer := &net.Dialer{
-		Timeout:   time.Duration(c.conf.Timeout) * time.Second,
+		Timeout:   time.Duration(c.conf.Other.Timeout) * time.Second,
 		KeepAlive: 30 * time.Second,
-		DualStack: true,
-		Resolver:  c.bootstrapResolver,
+		// DualStack: true,
+		Resolver: c.bootstrapResolver,
 	}
 	c.httpTransport = &http.Transport{
 		DialContext:           dialer.DialContext,
@@ -172,9 +246,9 @@ func (c *Client) newHTTPClient() error {
 		MaxIdleConns:          100,
 		MaxIdleConnsPerHost:   10,
 		Proxy:                 http.ProxyFromEnvironment,
-		TLSHandshakeTimeout:   time.Duration(c.conf.Timeout) * time.Second,
+		TLSHandshakeTimeout:   time.Duration(c.conf.Other.Timeout) * time.Second,
 	}
-	if c.conf.NoIPv6 {
+	if c.conf.Other.NoIPv6 {
 		c.httpTransport.DialContext = func(ctx context.Context, network, address string) (net.Conn, error) {
 			if strings.HasPrefix(network, "tcp") {
 				network = "tcp4"
@@ -206,6 +280,9 @@ func (c *Client) Start() error {
 		}(srv)
 	}
 
+	// start evaluation loop
+	c.selector.StartEvaluate()
+
 	for i := 0; i < cap(results); i++ {
 		err := <-results
 		if err != nil {
@@ -213,11 +290,12 @@ func (c *Client) Start() error {
 		}
 	}
 	close(results)
+
 	return nil
 }
 
 func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
-	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(c.conf.Timeout)*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(c.conf.Other.Timeout)*time.Second)
 	defer cancel()
 
 	if r.Response {
@@ -246,7 +324,7 @@ func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
 	} else {
 		questionType = strconv.FormatUint(uint64(question.Qtype), 10)
 	}
-	if c.conf.Verbose {
+	if c.conf.Other.Verbose {
 		fmt.Printf("%s - - [%s] \"%s %s %s\"\n", w.RemoteAddr(), time.Now().Format("02/Jan/2006:15:04:05 -0700"), questionName, questionClass, questionType)
 	}
 
@@ -284,64 +362,80 @@ func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
 		return
 	}
 
-	requestType := ""
-	if len(c.conf.UpstreamIETF) == 0 {
-		requestType = "application/dns-json"
-	} else if len(c.conf.UpstreamGoogle) == 0 {
-		requestType = "application/dns-message"
-	} else {
-		numServers := len(c.conf.UpstreamGoogle) + len(c.conf.UpstreamIETF)
-		random := rand.Intn(numServers)
-		if random < len(c.conf.UpstreamGoogle) {
-			requestType = "application/dns-json"
-		} else {
-			requestType = "application/dns-message"
-		}
+	upstream := c.selector.Get()
+	requestType := upstream.RequestType
+
+	if c.conf.Other.Verbose {
+		log.Println("choose upstream:", upstream)
 	}
 
 	var req *DNSRequest
-	if requestType == "application/dns-json" {
-		req = c.generateRequestGoogle(ctx, w, r, isTCP)
-	} else if requestType == "application/dns-message" {
-		req = c.generateRequestIETF(ctx, w, r, isTCP)
-	} else {
+	switch requestType {
+	case "application/dns-json":
+		req = c.generateRequestGoogle(ctx, w, r, isTCP, upstream)
+
+	case "application/dns-message":
+		req = c.generateRequestIETF(ctx, w, r, isTCP, upstream)
+
+	default:
 		panic("Unknown request Content-Type")
 	}
 
-	if req.response != nil {
-		defer req.response.Body.Close()
-		for _, header := range c.conf.DebugHTTPHeaders {
-			if value := req.response.Header.Get(header); value != "" {
-				log.Printf("%s: %s\n", header, value)
+	if req.err != nil {
+		if urlErr, ok := req.err.(*url.Error); ok {
+			// should we only check timeout?
+			if urlErr.Timeout() {
+				c.selector.ReportUpstreamStatus(upstream, selector.Timeout)
 			}
 		}
-	}
-	if req.err != nil {
+
 		return
 	}
 
-	contentType := ""
-	candidateType := strings.SplitN(req.response.Header.Get("Content-Type"), ";", 2)[0]
-	if candidateType == "application/json" {
-		contentType = "application/json"
-	} else if candidateType == "application/dns-message" {
-		contentType = "application/dns-message"
-	} else if candidateType == "application/dns-udpwireformat" {
-		contentType = "application/dns-message"
-	} else {
-		if requestType == "application/dns-json" {
-			contentType = "application/json"
-		} else if requestType == "application/dns-message" {
-			contentType = "application/dns-message"
+	// if req.err == nil, req.response != nil
+	defer req.response.Body.Close()
+
+	for _, header := range c.conf.Other.DebugHTTPHeaders {
+		if value := req.response.Header.Get(header); value != "" {
+			log.Printf("%s: %s\n", header, value)
 		}
 	}
 
-	if contentType == "application/json" {
+	candidateType := strings.SplitN(req.response.Header.Get("Content-Type"), ";", 2)[0]
+
+	switch candidateType {
+	case "application/json":
 		c.parseResponseGoogle(ctx, w, r, isTCP, req)
-	} else if contentType == "application/dns-message" {
+
+	case "application/dns-message", "application/dns-udpwireformat":
 		c.parseResponseIETF(ctx, w, r, isTCP, req)
-	} else {
-		panic("Unknown response Content-Type")
+
+	default:
+		switch requestType {
+		case "application/dns-json":
+			c.parseResponseGoogle(ctx, w, r, isTCP, req)
+
+		case "application/dns-message":
+			c.parseResponseIETF(ctx, w, r, isTCP, req)
+
+		default:
+			panic("Unknown response Content-Type")
+		}
+	}
+
+	// https://developers.cloudflare.com/1.1.1.1/dns-over-https/request-structure/ says
+	// returns code will be 200 / 400 / 413 / 415 / 504, some server will return 503, so
+	// I think if status code is 5xx, upstream must has some problems
+	/*if req.response.StatusCode/100 == 5 {
+		c.selector.ReportUpstreamStatus(upstream, selector.Medium)
+	}*/
+
+	switch req.response.StatusCode / 100 {
+	case 5:
+		c.selector.ReportUpstreamStatus(upstream, selector.Error)
+
+	case 2:
+		c.selector.ReportUpstreamStatus(upstream, selector.OK)
 	}
 }
 
@@ -360,7 +454,7 @@ var (
 
 func (c *Client) findClientIP(w dns.ResponseWriter, r *dns.Msg) (ednsClientAddress net.IP, ednsClientNetmask uint8) {
 	ednsClientNetmask = 255
-	if c.conf.NoECS {
+	if c.conf.Other.NoECS {
 		return net.IPv4(0, 0, 0, 0), 0
 	}
 	if opt := r.IsEdns0(); opt != nil {

doh-client/config/config.go

@@ -21,7 +21,7 @@
    DEALINGS IN THE SOFTWARE.
 */
 
-package main
+package config
 
 import (
 	"fmt"
@@ -29,10 +29,24 @@ import (
 	"github.com/BurntSushi/toml"
 )
 
-type config struct {
-	Listen           []string `toml:"listen"`
-	UpstreamGoogle   []string `toml:"upstream_google"`
-	UpstreamIETF     []string `toml:"upstream_ietf"`
+const (
+	Random   = "random"
+	NginxWRR = "weighted_round_robin"
+	LVSWRR   = "lvs_weighted_round_robin"
+)
+
+type upstreamDetail struct {
+	URL    string `toml:"url"`
+	Weight int32  `toml:"weight"`
+}
+
+type upstream struct {
+	UpstreamGoogle   []upstreamDetail `toml:"upstream_google"`
+	UpstreamIETF     []upstreamDetail `toml:"upstream_ietf"`
+	UpstreamSelector string           `toml:"upstream_selector"` // usable: random or weighted_random
+}
+
+type others struct {
 	Bootstrap        []string `toml:"bootstrap"`
 	Passthrough      []string `toml:"passthrough"`
 	Timeout          uint     `toml:"timeout"`
@@ -43,8 +57,14 @@ type config struct {
 	DebugHTTPHeaders []string `toml:"debug_http_headers"`
 }
 
-func loadConfig(path string) (*config, error) {
-	conf := &config{}
+type Config struct {
+	Listen   []string `toml:"listen"`
+	Upstream upstream `toml:"upstream"`
+	Other    others   `toml:"others"`
+}
+
+func LoadConfig(path string) (*Config, error) {
+	conf := &Config{}
 	metaData, err := toml.DecodeFile(path, conf)
 	if err != nil {
 		return nil, err
@@ -56,11 +76,15 @@ func loadConfig(path string) (*config, error) {
 	if len(conf.Listen) == 0 {
 		conf.Listen = []string{"127.0.0.1:53", "[::1]:53"}
 	}
-	if len(conf.UpstreamGoogle) == 0 && len(conf.UpstreamIETF) == 0 {
-		conf.UpstreamGoogle = []string{"https://dns.google.com/resolve"}
+	if len(conf.Upstream.UpstreamGoogle) == 0 && len(conf.Upstream.UpstreamIETF) == 0 {
+		conf.Upstream.UpstreamGoogle = []upstreamDetail{{URL: "https://dns.google.com/resolve", Weight: 50}}
 	}
-	if conf.Timeout == 0 {
-		conf.Timeout = 10
+	if conf.Other.Timeout == 0 {
+		conf.Other.Timeout = 10
+	}
+
+	if conf.Upstream.UpstreamSelector == "" {
+		conf.Upstream.UpstreamSelector = Random
 	}
 
 	return conf, nil

doh-client/doh-client.conf

@@ -7,40 +7,53 @@ listen = [
 ]
 
 # HTTP path for upstream resolver
-# If multiple servers are specified, a random one will be chosen each time.
-upstream_google = [
 
-    # Google's productive resolver, good ECS, bad DNSSEC
-    "https://dns.google.com/resolve",
+[upstream]
 
-    # CloudFlare's resolver, bad ECS, good DNSSEC
-    #"https://cloudflare-dns.com/dns-query",
-    #"https://1.1.1.1/dns-query",
-    #"https://1.0.0.1/dns-query",
+# available selector: random or weighted_round_robin or lvs_weighted_round_robin
+upstream_selector = "random"
 
-    # CloudFlare's resolver for Tor, available only with Tor
-    # Remember to disable ECS below when using Tor!
-    # Blog: https://blog.cloudflare.com/welcome-hidden-resolver/
-    #"https://dns4torpnlfs2ifuz2s2yf3fc7rdmsbhm6rw75euj35pac6ap25zgqad.onion/dns-query",
+# weight should in (0, 100], if upstream_selector is random, weight will be ignored
 
-]
-upstream_ietf = [
+## Google's productive resolver, good ECS, bad DNSSEC
+#[[upstream.upstream_google]]
+#    url = "https://dns.google.com/resolve"
+#    weight = 50
 
-    # Google's experimental resolver, good ECS, good DNSSEC
-    #"https://dns.google.com/experimental",
+## CloudFlare's resolver, bad ECS, good DNSSEC
+#[[upstream.upstream_google]]
+#    url = "https://cloudflare-dns.com/dns-query"
+#    weight = 50
 
-    # CloudFlare's resolver, bad ECS, good DNSSEC
-    #"https://cloudflare-dns.com/dns-query",
-    #"https://1.1.1.1/dns-query",
-    #"https://1.0.0.1/dns-query",
+## CloudFlare's resolver, bad ECS, good DNSSEC
+#[[upstream.upstream_google]]
+#    url = "https://1.1.1.1/dns-query"
+#    weight = 50
 
-    # CloudFlare's resolver for Tor, available only with Tor
-    # Remember to disable ECS below when using Tor!
-    # Blog: https://blog.cloudflare.com/welcome-hidden-resolver/
-    #"https://dns4torpnlfs2ifuz2s2yf3fc7rdmsbhm6rw75euj35pac6ap25zgqad.onion/dns-query",
+# CloudFlare's resolver, bad ECS, good DNSSEC
+[[upstream.upstream_ietf]]
+    url = "https://cloudflare-dns.com/dns-query"
+    weight = 50
 
-]
+## CloudFlare's resolver, bad ECS, good DNSSEC
+#[[upstream.upstream_ietf]]
+#    url = "https://1.1.1.1/dns-query"
+#    weight = 50
 
+## Google's experimental resolver, good ECS, good DNSSEC
+#[[upstream.upstream_ietf]]
+#    url = "https://dns.google.com/experimental"
+#    weight = 50
+
+## CloudFlare's resolver for Tor, available only with Tor
+## Remember to disable ECS below when using Tor!
+## Blog: https://blog.cloudflare.com/welcome-hidden-resolver/
+#[[upstream.upstream_ietf]]
+#    url = "https://dns4torpnlfs2ifuz2s2yf3fc7rdmsbhm6rw75euj35pac6ap25zgqad.onion/dns-query"
+#    weight = 50
+
+
+[others]
 # Bootstrap DNS server to resolve the address of the upstream resolver
 # If multiple servers are specified, a random one will be chosen each time.
 # If empty, use the system DNS settings.
@@ -76,7 +89,7 @@ passthrough = [
     "time.windows.com",
 ]
 
-# Timeout for upstream request
+# Timeout for upstream request in seconds
 timeout = 30
 
 # Disable HTTP Cookies

doh-client/google.go

@@ -29,17 +29,17 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
-	"math/rand"
 	"net/http"
 	"net/url"
 	"strconv"
 	"strings"
 
+	"github.com/m13253/dns-over-https/doh-client/selector"
 	"github.com/m13253/dns-over-https/json-dns"
 	"github.com/miekg/dns"
 )
 
-func (c *Client) generateRequestGoogle(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool) *DNSRequest {
+func (c *Client) generateRequestGoogle(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, upstream *selector.Upstream) *DNSRequest {
 	question := &r.Question[0]
 	questionName := question.Name
 	questionClass := question.Qclass
@@ -58,9 +58,7 @@ func (c *Client) generateRequestGoogle(ctx context.Context, w dns.ResponseWriter
 		questionType = strconv.FormatUint(uint64(question.Qtype), 10)
 	}
 
-	numServers := len(c.conf.UpstreamGoogle)
-	upstream := c.conf.UpstreamGoogle[rand.Intn(numServers)]
-	requestURL := fmt.Sprintf("%s?ct=application/dns-json&name=%s&type=%s", upstream, url.QueryEscape(questionName), url.QueryEscape(questionType))
+	requestURL := fmt.Sprintf("%s?ct=application/dns-json&name=%s&type=%s", upstream.URL, url.QueryEscape(questionName), url.QueryEscape(questionType))
 
 	if r.CheckingDisabled {
 		requestURL += "&cd=1"
@@ -76,7 +74,7 @@ func (c *Client) generateRequestGoogle(ctx context.Context, w dns.ResponseWriter
 		requestURL += fmt.Sprintf("&edns_client_subnet=%s/%d", ednsClientAddress.String(), ednsClientNetmask)
 	}
 
-	req, err := http.NewRequest("GET", requestURL, nil)
+	req, err := http.NewRequest(http.MethodGet, requestURL, nil)
 	if err != nil {
 		log.Println(err)
 		reply := jsonDNS.PrepareReply(r)
@@ -86,19 +84,24 @@ func (c *Client) generateRequestGoogle(ctx context.Context, w dns.ResponseWriter
 			err: err,
 		}
 	}
+
 	req.Header.Set("Accept", "application/json, application/dns-message, application/dns-udpwireformat")
 	req.Header.Set("User-Agent", USER_AGENT)
 	req = req.WithContext(ctx)
+
 	c.httpClientMux.RLock()
 	resp, err := c.httpClient.Do(req)
 	c.httpClientMux.RUnlock()
-	if err == context.DeadlineExceeded {
+
+	// if http Client.Do returns non-nil error, it always *url.Error
+	/*if err == context.DeadlineExceeded {
 		// Do not respond, silently fail to prevent caching of SERVFAIL
 		log.Println(err)
 		return &DNSRequest{
 			err: err,
 		}
-	}
+	}*/
+
 	if err != nil {
 		log.Println(err)
 		reply := jsonDNS.PrepareReply(r)
@@ -115,12 +118,12 @@ func (c *Client) generateRequestGoogle(ctx context.Context, w dns.ResponseWriter
 		udpSize:           udpSize,
 		ednsClientAddress: ednsClientAddress,
 		ednsClientNetmask: ednsClientNetmask,
-		currentUpstream:   upstream,
+		currentUpstream:   upstream.URL,
 	}
 }
 
 func (c *Client) parseResponseGoogle(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
-	if req.response.StatusCode != 200 {
+	if req.response.StatusCode != http.StatusOK {
 		log.Printf("HTTP error from upstream %s: %s\n", req.currentUpstream, req.response.Status)
 		req.reply.Rcode = dns.RcodeServerFailure
 		contentType := req.response.Header.Get("Content-Type")

doh-client/ietf.go

@@ -30,17 +30,17 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
-	"math/rand"
 	"net"
 	"net/http"
 	"strings"
 	"time"
 
+	"github.com/m13253/dns-over-https/doh-client/selector"
 	"github.com/m13253/dns-over-https/json-dns"
 	"github.com/miekg/dns"
 )
 
-func (c *Client) generateRequestIETF(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool) *DNSRequest {
+func (c *Client) generateRequestIETF(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, upstream *selector.Upstream) *DNSRequest {
 	opt := r.IsEdns0()
 	udpSize := uint16(512)
 	if opt == nil {
@@ -100,13 +100,11 @@ func (c *Client) generateRequestIETF(ctx context.Context, w dns.ResponseWriter,
 	r.Id = requestID
 	requestBase64 := base64.RawURLEncoding.EncodeToString(requestBinary)
 
-	numServers := len(c.conf.UpstreamIETF)
-	upstream := c.conf.UpstreamIETF[rand.Intn(numServers)]
-	requestURL := fmt.Sprintf("%s?ct=application/dns-message&dns=%s", upstream, requestBase64)
+	requestURL := fmt.Sprintf("%s?ct=application/dns-message&dns=%s", upstream.URL, requestBase64)
 
 	var req *http.Request
 	if len(requestURL) < 2048 {
-		req, err = http.NewRequest("GET", requestURL, nil)
+		req, err = http.NewRequest(http.MethodGet, requestURL, nil)
 		if err != nil {
 			log.Println(err)
 			reply := jsonDNS.PrepareReply(r)
@@ -117,7 +115,7 @@ func (c *Client) generateRequestIETF(ctx context.Context, w dns.ResponseWriter,
 			}
 		}
 	} else {
-		req, err = http.NewRequest("POST", upstream, bytes.NewReader(requestBinary))
+		req, err = http.NewRequest(http.MethodPost, upstream.URL, bytes.NewReader(requestBinary))
 		if err != nil {
 			log.Println(err)
 			reply := jsonDNS.PrepareReply(r)
@@ -135,13 +133,16 @@ func (c *Client) generateRequestIETF(ctx context.Context, w dns.ResponseWriter,
 	c.httpClientMux.RLock()
 	resp, err := c.httpClient.Do(req)
 	c.httpClientMux.RUnlock()
-	if err == context.DeadlineExceeded {
+
+	// if http Client.Do returns non-nil error, it always *url.Error
+	/*if err == context.DeadlineExceeded {
 		// Do not respond, silently fail to prevent caching of SERVFAIL
 		log.Println(err)
 		return &DNSRequest{
 			err: err,
 		}
-	}
+	}*/
+
 	if err != nil {
 		log.Println(err)
 		reply := jsonDNS.PrepareReply(r)
@@ -158,12 +159,12 @@ func (c *Client) generateRequestIETF(ctx context.Context, w dns.ResponseWriter,
 		udpSize:           udpSize,
 		ednsClientAddress: ednsClientAddress,
 		ednsClientNetmask: ednsClientNetmask,
-		currentUpstream:   upstream,
+		currentUpstream:   upstream.URL,
 	}
 }
 
 func (c *Client) parseResponseIETF(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
-	if req.response.StatusCode != 200 {
+	if req.response.StatusCode != http.StatusOK {
 		log.Printf("HTTP error from upstream %s: %s\n", req.currentUpstream, req.response.Status)
 		req.reply.Rcode = dns.RcodeServerFailure
 		contentType := req.response.Header.Get("Content-Type")

doh-client/main.go

@@ -32,6 +32,8 @@ import (
 	"os"
 	"runtime"
 	"strconv"
+
+	"github.com/m13253/dns-over-https/doh-client/config"
 )
 
 func checkPIDFile(pidFile string) (bool, error) {
@@ -101,13 +103,13 @@ func main() {
 		}
 	}
 
-	conf, err := loadConfig(*confPath)
+	conf, err := config.LoadConfig(*confPath)
 	if err != nil {
 		log.Fatalln(err)
 	}
 
 	if *verbose {
-		conf.Verbose = true
+		conf.Other.Verbose = true
 	}
 
 	client, err := NewClient(conf)

doh-client/selector/lvsWRRSelector.go

@@ -0,0 +1,262 @@
+package selector
+
+import (
+	"encoding/json"
+	"errors"
+	"log"
+	"net/http"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+type LVSWRRSelector struct {
+	upstreams     []*Upstream // upstreamsInfo
+	client        http.Client // http client to check the upstream
+	lastChoose    int32
+	currentWeight int32
+}
+
+func NewLVSWRRSelector(timeout time.Duration) *LVSWRRSelector {
+	return &LVSWRRSelector{
+		client:     http.Client{Timeout: timeout},
+		lastChoose: -1,
+	}
+}
+
+func (ls *LVSWRRSelector) Add(url string, upstreamType UpstreamType, weight int32) (err error) {
+	if weight < 1 {
+		return errors.New("weight is 1")
+	}
+
+	switch upstreamType {
+	case Google:
+		ls.upstreams = append(ls.upstreams, &Upstream{
+			Type:            Google,
+			URL:             url,
+			RequestType:     "application/dns-json",
+			weight:          weight,
+			effectiveWeight: weight,
+		})
+
+	case IETF:
+		ls.upstreams = append(ls.upstreams, &Upstream{
+			Type:            IETF,
+			URL:             url,
+			RequestType:     "application/dns-message",
+			weight:          weight,
+			effectiveWeight: weight,
+		})
+
+	default:
+		return errors.New("unknown upstream type")
+	}
+
+	return nil
+}
+
+func (ls *LVSWRRSelector) StartEvaluate() {
+	go func() {
+		for {
+			wg := sync.WaitGroup{}
+
+			for i := range ls.upstreams {
+				wg.Add(1)
+
+				go func(i int) {
+					defer wg.Done()
+
+					upstreamURL := ls.upstreams[i].URL
+					var acceptType string
+
+					switch ls.upstreams[i].Type {
+					case Google:
+						upstreamURL += "?name=www.example.com&type=A"
+						acceptType = "application/dns-json"
+
+					case IETF:
+						// www.example.com
+						upstreamURL += "?dns=q80BAAABAAAAAAAAA3d3dwdleGFtcGxlA2NvbQAAAQAB"
+						acceptType = "application/dns-message"
+					}
+
+					req, err := http.NewRequest(http.MethodGet, upstreamURL, nil)
+					if err != nil {
+						/*log.Println("upstream:", upstreamURL, "type:", typeMap[upstream.Type], "check failed:", err)
+						continue*/
+
+						// should I only log it? But if there is an error, I think when query the server will return error too
+						panic("upstream: " + upstreamURL + " type: " + typeMap[ls.upstreams[i].Type] + " check failed: " + err.Error())
+					}
+
+					req.Header.Set("accept", acceptType)
+
+					resp, err := ls.client.Do(req)
+					if err != nil {
+						// should I check error in detail?
+						if atomic.AddInt32(&ls.upstreams[i].effectiveWeight, -5) < 1 {
+							atomic.StoreInt32(&ls.upstreams[i].effectiveWeight, 1)
+						}
+						return
+					}
+
+					switch ls.upstreams[i].Type {
+					case Google:
+						ls.checkGoogleResponse(resp, ls.upstreams[i])
+
+					case IETF:
+						ls.checkIETFResponse(resp, ls.upstreams[i])
+					}
+				}(i)
+			}
+
+			wg.Wait()
+
+			time.Sleep(15 * time.Second)
+		}
+	}()
+}
+
+func (ls *LVSWRRSelector) Get() *Upstream {
+	if len(ls.upstreams) == 1 {
+		return ls.upstreams[0]
+	}
+
+	for {
+		atomic.StoreInt32(&ls.lastChoose, (atomic.LoadInt32(&ls.lastChoose)+1)%int32(len(ls.upstreams)))
+
+		if atomic.LoadInt32(&ls.lastChoose) == 0 {
+			atomic.AddInt32(&ls.currentWeight, -ls.gcdWeight())
+
+			if atomic.LoadInt32(&ls.currentWeight) <= 0 {
+				atomic.AddInt32(&ls.currentWeight, ls.maxWeight())
+
+				if atomic.LoadInt32(&ls.currentWeight) == 0 {
+					panic("current weight is 0")
+				}
+			}
+		}
+
+		if atomic.LoadInt32(&ls.upstreams[atomic.LoadInt32(&ls.lastChoose)].effectiveWeight) >= atomic.LoadInt32(&ls.currentWeight) {
+			return ls.upstreams[atomic.LoadInt32(&ls.lastChoose)]
+		}
+	}
+}
+
+func (ls *LVSWRRSelector) gcdWeight() (res int32) {
+	res = gcd(atomic.LoadInt32(&ls.upstreams[0].effectiveWeight), atomic.LoadInt32(&ls.upstreams[0].effectiveWeight))
+
+	for i := 1; i < len(ls.upstreams); i++ {
+		res = gcd(res, atomic.LoadInt32(&ls.upstreams[i].effectiveWeight))
+	}
+
+	return
+}
+
+func (ls *LVSWRRSelector) maxWeight() (res int32) {
+	for _, upstream := range ls.upstreams {
+		w := atomic.LoadInt32(&upstream.effectiveWeight)
+		if w > res {
+			res = w
+		}
+	}
+
+	return
+}
+
+func gcd(x, y int32) int32 {
+	for {
+		if x < y {
+			x, y = y, x
+		}
+
+		tmp := x % y
+		if tmp == 0 {
+			return y
+		}
+
+		x = tmp
+	}
+}
+
+func (ls *LVSWRRSelector) ReportUpstreamStatus(upstream *Upstream, upstreamStatus upstreamStatus) {
+	switch upstreamStatus {
+	case Timeout:
+		if atomic.AddInt32(&upstream.effectiveWeight, -5) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+
+	case Error:
+		if atomic.AddInt32(&upstream.effectiveWeight, -2) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+
+	case OK:
+		if atomic.AddInt32(&upstream.effectiveWeight, 1) > upstream.weight {
+			atomic.StoreInt32(&upstream.effectiveWeight, upstream.weight)
+		}
+	}
+}
+
+func (ls *LVSWRRSelector) checkGoogleResponse(resp *http.Response, upstream *Upstream) {
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		// server error
+		if atomic.AddInt32(&upstream.effectiveWeight, -3) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+		return
+	}
+
+	m := make(map[string]interface{})
+	if err := json.NewDecoder(resp.Body).Decode(&m); err != nil {
+		// should I check error in detail?
+		if atomic.AddInt32(&upstream.effectiveWeight, -2) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+		return
+	}
+
+	if status, ok := m["Status"]; ok {
+		if statusNum, ok := status.(float64); ok && statusNum == 0 {
+			if atomic.AddInt32(&upstream.effectiveWeight, 5) > upstream.weight {
+				atomic.StoreInt32(&upstream.effectiveWeight, upstream.weight)
+			}
+			return
+		}
+	}
+
+	// should I check error in detail?
+	if atomic.AddInt32(&upstream.effectiveWeight, -2) < 1 {
+		atomic.StoreInt32(&upstream.effectiveWeight, 1)
+	}
+}
+
+func (ls *LVSWRRSelector) checkIETFResponse(resp *http.Response, upstream *Upstream) {
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		// server error
+		if atomic.AddInt32(&upstream.effectiveWeight, -3) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+		return
+	}
+
+	if atomic.AddInt32(&upstream.effectiveWeight, 5) > upstream.weight {
+		atomic.StoreInt32(&upstream.effectiveWeight, upstream.weight)
+	}
+}
+
+func (ls *LVSWRRSelector) ReportWeights() {
+	go func() {
+		for {
+			time.Sleep(15 * time.Second)
+
+			for _, u := range ls.upstreams {
+				log.Printf("%s, effect weight: %d", u, atomic.LoadInt32(&u.effectiveWeight))
+			}
+		}
+	}()
+}

doh-client/selector/nginxWRRSelector.go

@@ -0,0 +1,215 @@
+package selector
+
+import (
+	"encoding/json"
+	"errors"
+	"log"
+	"net/http"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+type NginxWRRSelector struct {
+	upstreams []*Upstream // upstreamsInfo
+	client    http.Client // http client to check the upstream
+}
+
+func NewNginxWRRSelector(timeout time.Duration) *NginxWRRSelector {
+	return &NginxWRRSelector{
+		client: http.Client{Timeout: timeout},
+	}
+}
+
+func (ws *NginxWRRSelector) Add(url string, upstreamType UpstreamType, weight int32) (err error) {
+	switch upstreamType {
+	case Google:
+		ws.upstreams = append(ws.upstreams, &Upstream{
+			Type:            Google,
+			URL:             url,
+			RequestType:     "application/dns-json",
+			weight:          weight,
+			effectiveWeight: weight,
+		})
+
+	case IETF:
+		ws.upstreams = append(ws.upstreams, &Upstream{
+			Type:            IETF,
+			URL:             url,
+			RequestType:     "application/dns-message",
+			weight:          weight,
+			effectiveWeight: weight,
+		})
+
+	default:
+		return errors.New("unknown upstream type")
+	}
+
+	return nil
+}
+
+func (ws *NginxWRRSelector) StartEvaluate() {
+	go func() {
+		for {
+			wg := sync.WaitGroup{}
+
+			for i := range ws.upstreams {
+				wg.Add(1)
+
+				go func(i int) {
+					defer wg.Done()
+
+					upstreamURL := ws.upstreams[i].URL
+					var acceptType string
+
+					switch ws.upstreams[i].Type {
+					case Google:
+						upstreamURL += "?name=www.example.com&type=A"
+						acceptType = "application/dns-json"
+
+					case IETF:
+						// www.example.com
+						upstreamURL += "?dns=q80BAAABAAAAAAAAA3d3dwdleGFtcGxlA2NvbQAAAQAB"
+						acceptType = "application/dns-message"
+					}
+
+					req, err := http.NewRequest(http.MethodGet, upstreamURL, nil)
+					if err != nil {
+						/*log.Println("upstream:", upstreamURL, "type:", typeMap[upstream.Type], "check failed:", err)
+						continue*/
+
+						// should I only log it? But if there is an error, I think when query the server will return error too
+						panic("upstream: " + upstreamURL + " type: " + typeMap[ws.upstreams[i].Type] + " check failed: " + err.Error())
+					}
+
+					req.Header.Set("accept", acceptType)
+
+					resp, err := ws.client.Do(req)
+					if err != nil {
+						// should I check error in detail?
+						if atomic.AddInt32(&ws.upstreams[i].effectiveWeight, -10) < 1 {
+							atomic.StoreInt32(&ws.upstreams[i].effectiveWeight, 1)
+						}
+						return
+					}
+
+					switch ws.upstreams[i].Type {
+					case Google:
+						ws.checkGoogleResponse(resp, ws.upstreams[i])
+
+					case IETF:
+						ws.checkIETFResponse(resp, ws.upstreams[i])
+					}
+				}(i)
+			}
+
+			wg.Wait()
+
+			time.Sleep(15 * time.Second)
+		}
+	}()
+}
+
+// nginx wrr like
+func (ws *NginxWRRSelector) Get() *Upstream {
+	var (
+		total             int32
+		bestUpstreamIndex = -1
+	)
+
+	for i := range ws.upstreams {
+		effectiveWeight := atomic.LoadInt32(&ws.upstreams[i].effectiveWeight)
+		atomic.AddInt32(&ws.upstreams[i].currentWeight, effectiveWeight)
+		total += effectiveWeight
+
+		if bestUpstreamIndex == -1 || atomic.LoadInt32(&ws.upstreams[i].currentWeight) > atomic.LoadInt32(&ws.upstreams[bestUpstreamIndex].currentWeight) {
+			bestUpstreamIndex = i
+		}
+	}
+
+	atomic.AddInt32(&ws.upstreams[bestUpstreamIndex].currentWeight, -total)
+
+	return ws.upstreams[bestUpstreamIndex]
+}
+
+func (ws *NginxWRRSelector) ReportUpstreamStatus(upstream *Upstream, upstreamStatus upstreamStatus) {
+	switch upstreamStatus {
+	case Timeout:
+		if atomic.AddInt32(&upstream.effectiveWeight, -5) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+
+	case Error:
+		if atomic.AddInt32(&upstream.effectiveWeight, -3) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+
+	case OK:
+		if atomic.AddInt32(&upstream.effectiveWeight, 1) > upstream.weight {
+			atomic.StoreInt32(&upstream.effectiveWeight, upstream.weight)
+		}
+	}
+}
+
+func (ws *NginxWRRSelector) checkGoogleResponse(resp *http.Response, upstream *Upstream) {
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		// server error
+		if atomic.AddInt32(&upstream.effectiveWeight, -3) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+		return
+	}
+
+	m := make(map[string]interface{})
+	if err := json.NewDecoder(resp.Body).Decode(&m); err != nil {
+		// should I check error in detail?
+		if atomic.AddInt32(&upstream.effectiveWeight, -2) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+		return
+	}
+
+	if status, ok := m["Status"]; ok {
+		if statusNum, ok := status.(float64); ok && statusNum == 0 {
+			if atomic.AddInt32(&upstream.effectiveWeight, 5) > upstream.weight {
+				atomic.StoreInt32(&upstream.effectiveWeight, upstream.weight)
+			}
+			return
+		}
+	}
+
+	// should I check error in detail?
+	if atomic.AddInt32(&upstream.effectiveWeight, -2) < 1 {
+		atomic.StoreInt32(&upstream.effectiveWeight, 1)
+	}
+}
+
+func (ws *NginxWRRSelector) checkIETFResponse(resp *http.Response, upstream *Upstream) {
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		// server error
+		if atomic.AddInt32(&upstream.effectiveWeight, -5) < 1 {
+			atomic.StoreInt32(&upstream.effectiveWeight, 1)
+		}
+		return
+	}
+
+	if atomic.AddInt32(&upstream.effectiveWeight, 5) > upstream.weight {
+		atomic.StoreInt32(&upstream.effectiveWeight, upstream.weight)
+	}
+}
+
+func (ws *NginxWRRSelector) ReportWeights() {
+	go func() {
+		for {
+			time.Sleep(15 * time.Second)
+
+			for _, u := range ws.upstreams {
+				log.Printf("%s, effect weight: %d", u, atomic.LoadInt32(&u.effectiveWeight))
+			}
+		}
+	}()
+}

doh-client/selector/randomSelector.go

@@ -0,0 +1,50 @@
+package selector
+
+import (
+	"errors"
+	"math/rand"
+	"time"
+)
+
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
+type RandomSelector struct {
+	upstreams []*Upstream
+}
+
+func NewRandomSelector() *RandomSelector {
+	return new(RandomSelector)
+}
+
+func (rs *RandomSelector) Add(url string, upstreamType UpstreamType) (err error) {
+	switch upstreamType {
+	case Google:
+		rs.upstreams = append(rs.upstreams, &Upstream{
+			Type:        Google,
+			URL:         url,
+			RequestType: "application/dns-json",
+		})
+
+	case IETF:
+		rs.upstreams = append(rs.upstreams, &Upstream{
+			Type:        IETF,
+			URL:         url,
+			RequestType: "application/dns-message",
+		})
+
+	default:
+		return errors.New("unknown upstream type")
+	}
+
+	return nil
+}
+
+func (rs *RandomSelector) Get() *Upstream {
+	return rs.upstreams[rand.Intn(len(rs.upstreams))]
+}
+
+func (rs *RandomSelector) StartEvaluate() {}
+
+func (rs *RandomSelector) ReportUpstreamStatus(upstream *Upstream, upstreamStatus upstreamStatus) {}

doh-client/selector/selector.go

@@ -0,0 +1,17 @@
+package selector
+
+type Selector interface {
+	// Get returns a upstream
+	Get() *Upstream
+
+	// StartEvaluate start upstream evaluation loop
+	StartEvaluate()
+
+	// ReportUpstreamStatus report upstream status
+	ReportUpstreamStatus(upstream *Upstream, upstreamStatus upstreamStatus)
+}
+
+type DebugReporter interface {
+	// ReportWeights starts a goroutine to report all upstream weights, recommend interval is 15s
+	ReportWeights()
+}

doh-client/selector/upstream.go

@@ -0,0 +1,28 @@
+package selector
+
+import "fmt"
+
+type UpstreamType int
+
+const (
+	Google UpstreamType = iota
+	IETF
+)
+
+var typeMap = map[UpstreamType]string{
+	Google: "Google",
+	IETF:   "IETF",
+}
+
+type Upstream struct {
+	Type            UpstreamType
+	URL             string
+	RequestType     string
+	weight          int32
+	effectiveWeight int32
+	currentWeight   int32
+}
+
+func (u Upstream) String() string {
+	return fmt.Sprintf("upstream type: %s, upstream url: %s", typeMap[u.Type], u.URL)
+}

doh-client/selector/upstreamStatus.go

@@ -0,0 +1,14 @@
+package selector
+
+type upstreamStatus int
+
+const (
+	// when query upstream timeout, usually upstream is unavailable for a long time
+	Timeout upstreamStatus = iota
+
+	// when query upstream return 5xx response, upstream still alive, maybe just a lof of query for him
+	Error
+
+	// when query upstream ok, means upstream is available
+	OK
+)

doh-client/version.go

@@ -24,6 +24,6 @@
 package main
 
 const (
-	VERSION    = "1.4.2"
+	VERSION    = "2.0.1"
 	USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"
 )

doh-server/config.go

@@ -31,6 +31,7 @@ import (
 
 type config struct {
 	Listen           []string `toml:"listen"`
+	LocalAddr        string   `toml:"local_addr"`
 	Cert             string   `toml:"cert"`
 	Key              string   `toml:"key"`
 	Path             string   `toml:"path"`
@@ -40,6 +41,7 @@ type config struct {
 	TCPOnly          bool     `toml:"tcp_only"`
 	Verbose          bool     `toml:"verbose"`
 	DebugHTTPHeaders []string `toml:"debug_http_headers"`
+	LogGuessedIP     bool     `toml:"log_guessed_client_ip"`
 }
 
 func loadConfig(path string) (*config, error) {

doh-server/doh-server.conf

@@ -4,6 +4,10 @@ listen = [
     "[::1]:8053",
 ]
 
+# Local address and port for upstream DNS
+# If left empty, a local address is automatically chosen.
+local_addr = ""
+
 # TLS certification file
 # If left empty, plain-text HTTP will be used.
 # You are recommended to leave empty and to use a server load balancer (e.g.
@@ -38,3 +42,7 @@ tcp_only = false
 
 # Enable logging
 verbose = false
+
+# Enable log IP from HTTPS-reverse proxy header: X-Forwarded-For or X-Real-IP
+# Note: http uri/useragent log cannot be controlled by this config
+log_guessed_client_ip = false

doh-server/ietf.go

@@ -30,6 +30,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	"net"
 	"net/http"
 	"strconv"
 	"strings"
@@ -94,7 +95,15 @@ func (s *Server) parseRequestIETF(ctx context.Context, w http.ResponseWriter, r
 		} else {
 			questionType = strconv.FormatUint(uint64(question.Qtype), 10)
 		}
-		fmt.Printf("%s - - [%s] \"%s %s %s\"\n", r.RemoteAddr, time.Now().Format("02/Jan/2006:15:04:05 -0700"), questionName, questionClass, questionType)
+		var clientip net.IP = nil
+		if s.conf.LogGuessedIP {
+			clientip = s.findClientIP(r)
+		}
+		if clientip != nil {
+			fmt.Printf("%s - - [%s] \"%s %s %s\"\n", clientip, time.Now().Format("02/Jan/2006:15:04:05 -0700"), questionName, questionClass, questionType)
+		} else {
+			fmt.Printf("%s - - [%s] \"%s %s %s\"\n", r.RemoteAddr, time.Now().Format("02/Jan/2006:15:04:05 -0700"), questionName, questionClass, questionType)
+		}
 	}
 
 	transactionID := msg.Id

doh-server/main.go

@@ -110,6 +110,9 @@ func main() {
 		conf.Verbose = true
 	}
 
-	server := NewServer(conf)
+	server, err := NewServer(conf)
+	if err != nil {
+		log.Fatalln(err)
+	}
 	_ = server.Start()
 }

doh-server/server.go

@@ -56,22 +56,41 @@ type DNSRequest struct {
 	errtext         string
 }
 
-func NewServer(conf *config) (s *Server) {
-	s = &Server{
+func NewServer(conf *config) (*Server, error) {
+	timeout := time.Duration(conf.Timeout) * time.Second
+	s := &Server{
 		conf: conf,
 		udpClient: &dns.Client{
 			Net:     "udp",
 			UDPSize: dns.DefaultMsgSize,
-			Timeout: time.Duration(conf.Timeout) * time.Second,
+			Timeout: timeout,
 		},
 		tcpClient: &dns.Client{
 			Net:     "tcp",
-			Timeout: time.Duration(conf.Timeout) * time.Second,
+			Timeout: timeout,
 		},
 		servemux: http.NewServeMux(),
 	}
+	if conf.LocalAddr != "" {
+		udpLocalAddr, err := net.ResolveUDPAddr("udp", conf.LocalAddr)
+		if err != nil {
+			return nil, err
+		}
+		tcpLocalAddr, err := net.ResolveTCPAddr("tcp", conf.LocalAddr)
+		if err != nil {
+			return nil, err
+		}
+		s.udpClient.Dialer = &net.Dialer{
+			Timeout:   timeout,
+			LocalAddr: udpLocalAddr,
+		}
+		s.tcpClient.Dialer = &net.Dialer{
+			Timeout:   timeout,
+			LocalAddr: tcpLocalAddr,
+		}
+	}
 	s.servemux.HandleFunc(conf.Path, s.handlerFunc)
-	return
+	return s, nil
 }
 
 func (s *Server) Start() error {

doh-server/version.go

@@ -24,6 +24,6 @@
 package main
 
 const (
-	VERSION    = "1.4.2"
+	VERSION    = "2.0.1"
 	USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"
 )

go.mod

@@ -0,0 +1,13 @@
+module github.com/m13253/dns-over-https
+
+go 1.12
+
+require (
+	github.com/BurntSushi/toml v0.3.1
+	github.com/gorilla/handlers v1.4.0
+	github.com/miekg/dns v1.1.6
+	golang.org/x/crypto v0.0.0-20190313024323-a1f597ede03a // indirect
+	golang.org/x/net v0.0.0-20190311183353-d8887717615a
+	golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6 // indirect
+	golang.org/x/sys v0.0.0-20190312061237-fead79001313 // indirect
+)

go.sum

@@ -0,0 +1,25 @@
+github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/gorilla/handlers v1.4.0 h1:XulKRWSQK5uChr4pEgSE4Tc/OcmnU9GJuSwdog/tZsA=
+github.com/gorilla/handlers v1.4.0/go.mod h1:Qkdc/uu4tH4g6mTK6auzZ766c4CA0Ng8+o/OAirnOIQ=
+github.com/miekg/dns v1.1.4 h1:rCMZsU2ScVSYcAsOXgmC6+AKOK+6pmQTOcw03nfwYV0=
+github.com/miekg/dns v1.1.4/go.mod h1:W1PPwlIAgtquWBMBEV9nkV9Cazfe8ScdGz/Lj7v3Nrg=
+github.com/miekg/dns v1.1.6 h1:jVwb4GDwD65q/gtItR/lIZHjNH93QfeGxZUkzJcW9mc=
+github.com/miekg/dns v1.1.6/go.mod h1:W1PPwlIAgtquWBMBEV9nkV9Cazfe8ScdGz/Lj7v3Nrg=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20190313024323-a1f597ede03a h1:YX8ljsm6wXlHZO+aRz9Exqr0evNhKRNe5K/gi+zKh4U=
+golang.org/x/crypto v0.0.0-20190313024323-a1f597ede03a/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190301231341-16b79f2e4e95 h1:fY7Dsw114eJN4boqzVSbpVHO6rTdhq6/GnXeu+PKnzU=
+golang.org/x/net v0.0.0-20190301231341-16b79f2e4e95/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a h1:oWX7TPOiFAMXLq8o0ikBYfCJVlRHBcsciT5bXOrH628=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6 h1:bjcUS9ztw9kFmmIxJInhon/0Is3p+EHBKNgquIzo1OI=
+golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190308023053-584f3b12f43e h1:K7CV15oJ823+HLXQ+M7MSMrUg8LjfqY7O3naO+8Pp/I=
+golang.org/x/sys v0.0.0-20190308023053-584f3b12f43e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190312061237-fead79001313 h1:pczuHS43Cp2ktBEEmLwScxgjWsBSzdaQiKzUyf3DTTc=
+golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=