Release 2.1.2

fix typo

.gitignore

@@ -12,3 +12,5 @@
 
 # Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736
 .glide/
+
+.idea/

Changelog.md

@@ -4,6 +4,54 @@ This Changelog records major changes between versions.
 
 Not all changes are recorded. Please check git log for details.
 
+## Version 2.1.2
+
+- Update address for google's resolver
+- Fix a typo
+
+## Version 2.1.1
+
+- Add a set of Dockerfile contributed by the community
+- Include DNS.SB's resolver in example configuration
+
+## Version 2.1.0
+
+- Add `local_addr` configuration for doh-server (#39)
+- Fix a problem when compiling on macOS 10.14.4 or newer
+- Add Quad9 DoH server to the example `doh-client.conf`
+- Use TCP when appropriate for the given query type/response (AXFR/IXFR)
+
+## 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.
+- Remove dns.ErrTruncated according to <https://github.com/miekg/dns/pull/815>.
+
+## Version 1.4.1
+
+- Add a configuration option: `debug_http_headers` (e.g. Add `CF-Ray` to diagnose Cloudflare's resolver)
+- Add a configuration option: `passrthrough`
+- macOS logger is rebuilt with static libswiftCore
+- Fix HTTP stream leaking problem, which may cause massive half-open connections if HTTP/1 is in use
+- Utilize Go's cancelable context to detect timeouts more reliably.
+- Fix interoperation problems with gDNS
+- CORS is enabled by default in doh-server
+- Documentation updates
+
+## Version 1.3.10
+
+- Enable application/dns-message (draft-13) by default, since Google has finally supported it
+
 ## Version 1.3.9
 
 - Fix client crash with `no_cookies = true`

Dockerfile.client

@@ -0,0 +1,22 @@
+FROM golang:alpine AS build-env
+
+RUN apk add --no-cache git make
+
+WORKDIR /src
+ADD . /src
+RUN make doh-client/doh-client
+
+FROM alpine:latest
+
+COPY --from=build-env /src/doh-client/doh-client /doh-client
+
+ADD doh-client/doh-client.conf /doh-client.conf
+
+RUN sed -i '$!N;s/"127.0.0.1:53",.*"127.0.0.1:5380",/":53",/;P;D' /doh-client.conf
+RUN sed -i '$!N;s/"\[::1\]:53",.*"\[::1\]:5380",/":5380",/;P;D' /doh-client.conf
+
+EXPOSE 53
+EXPOSE 5380
+
+ENTRYPOINT ["/doh-client"]
+CMD ["-conf", "/doh-client.conf"]

Dockerfile.server

@@ -0,0 +1,20 @@
+FROM golang:alpine AS build-env
+
+RUN apk add --no-cache git make
+
+WORKDIR /src
+ADD . /src
+RUN make doh-server/doh-server
+
+FROM alpine:latest
+
+COPY --from=build-env /src/doh-server/doh-server /doh-server
+
+ADD doh-server/doh-server.conf /doh-server.conf
+
+RUN sed -i '$!N;s/"127.0.0.1:8053",\s*"\[::1\]:8053",/":8053",/;P;D' /doh-server.conf
+
+EXPOSE 8053
+
+ENTRYPOINT ["/doh-server"]
+CMD ["-conf", "/doh-server.conf"]

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

Readme.md

@@ -2,11 +2,15 @@ DNS-over-HTTPS
 ==============
 
 Client and server software to query DNS over HTTPS, using [Google DNS-over-HTTPS protocol](https://developers.google.com/speed/public-dns/docs/dns-over-https)
-and [draft-ietf-doh-dns-over-https](https://github.com/dohwg/draft-ietf-doh-dns-over-https).
+and [IETF DNS-over-HTTPS (RFC 8484)](https://www.rfc-editor.org/rfc/rfc8484.txt).
 
-## Easy start
+## Guide
 
-Install [Go](https://golang.org), at least version 1.9.
+[Tutorial to setup your own DNS-over-HTTPS (DoH) server](https://www.aaflalo.me/2018/10/tutorial-setup-dns-over-https-server/). (Thanks to Antoine Aflalo)
+
+## Installing
+
+Install [Go](https://golang.org), at least version 1.10.
 
 (Note for Debian/Ubuntu users: You need to set `$GOROOT` if you could not get your new version of Go selected by the Makefile.)
 
@@ -109,11 +113,9 @@ except for absolute expire time is preferred to relative TTL value. Refer to
 [json-dns/response.go](json-dns/response.go) for a complete description of the
 API.
 
-### IETF DNS-over-HTTPS Protocol (Draft)
+### IETF DNS-over-HTTPS Protocol
 
-DNS-over-HTTPS uses a protocol compatible to [draft-ietf-doh-dns-over-https](https://github.com/dohwg/draft-ietf-doh-dns-over-https).
-This protocol is in draft stage. Any incompatibility may be introduced before
-it is finished.
+DNS-over-HTTPS uses a protocol compatible to [IETF DNS-over-HTTPS (RFC 8484)](https://www.rfc-editor.org/rfc/rfc8484.txt).
 
 ### Supported features
 

doh-client/client.go

@@ -25,23 +25,32 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"log"
 	"math/rand"
 	"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"
+	"golang.org/x/net/idna"
 )
 
 type Client struct {
-	conf                 *config
+	conf                 *config.Config
 	bootstrap            []string
+	passthrough          []string
+	udpClient            *dns.Client
+	tcpClient            *dns.Client
 	udpServers           []*dns.Server
 	tcpServers           []*dns.Server
 	bootstrapResolver    *net.Resolver
@@ -50,6 +59,7 @@ type Client struct {
 	httpTransport        *http.Transport
 	httpClient           *http.Client
 	httpClientLastCreate time.Time
+	selector             selector.Selector
 }
 
 type DNSRequest struct {
@@ -62,13 +72,22 @@ 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,
 	}
 
 	udpHandler := dns.HandlerFunc(c.udpHandlerFunc)
 	tcpHandler := dns.HandlerFunc(c.tcpHandlerFunc)
+	c.udpClient = &dns.Client{
+		Net:     "udp",
+		UDPSize: dns.DefaultMsgSize,
+		Timeout: time.Duration(conf.Other.Timeout) * time.Second,
+	}
+	c.tcpClient = &dns.Client{
+		Net:     "tcp",
+		Timeout: time.Duration(conf.Other.Timeout) * time.Second,
+	}
 	for _, addr := range conf.Listen {
 		c.udpServers = append(c.udpServers, &dns.Server{
 			Addr:    addr,
@@ -83,9 +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")
@@ -105,38 +124,120 @@ func NewClient(conf *config) (c *Client, err error) {
 				return conn, err
 			},
 		}
+		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
+				}
+				c.passthrough[i] = "." + strings.ToLower(strings.Trim(passthrough, ".")) + "."
+			}
+		}
 	}
 	// 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
 		}
+	} else {
+		c.cookieJar = nil
 	}
+
 	c.httpClientMux = new(sync.RWMutex)
 	err = c.newHTTPClient()
 	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.Now().Sub(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,
@@ -145,10 +246,9 @@ func (c *Client) newHTTPClient() error {
 		MaxIdleConns:          100,
 		MaxIdleConnsPerHost:   10,
 		Proxy:                 http.ProxyFromEnvironment,
-		ResponseHeaderTimeout: time.Duration(c.conf.Timeout) * time.Second,
-		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"
@@ -180,6 +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 {
@@ -187,65 +290,152 @@ func (c *Client) Start() error {
 		}
 	}
 	close(results)
+
 	return nil
 }
 
 func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
-	if r.Response == true {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(c.conf.Other.Timeout)*time.Second)
+	defer cancel()
+
+	if r.Response {
 		log.Println("Received a response packet")
 		return
 	}
 
-	requestType := ""
-	if len(c.conf.UpstreamIETF) == 0 {
-		requestType = "application/dns-json"
-	} else if len(c.conf.UpstreamGoogle) == 0 {
-		requestType = "application/dns-message"
+	if len(r.Question) != 1 {
+		log.Println("Number of questions is not 1")
+		reply := jsonDNS.PrepareReply(r)
+		reply.Rcode = dns.RcodeFormatError
+		w.WriteMsg(reply)
+		return
+	}
+	question := &r.Question[0]
+	questionName := question.Name
+	questionClass := ""
+	if qclass, ok := dns.ClassToString[question.Qclass]; ok {
+		questionClass = qclass
 	} 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"
+		questionClass = strconv.FormatUint(uint64(question.Qclass), 10)
+	}
+	questionType := ""
+	if qtype, ok := dns.TypeToString[question.Qtype]; ok {
+		questionType = qtype
+	} else {
+		questionType = strconv.FormatUint(uint64(question.Qtype), 10)
+	}
+	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)
+	}
+
+	shouldPassthrough := false
+	passthroughQuestionName := questionName
+	if punycode, err := idna.ToASCII(passthroughQuestionName); err != nil {
+		passthroughQuestionName = punycode
+	}
+	passthroughQuestionName = "." + strings.ToLower(strings.Trim(passthroughQuestionName, ".")) + "."
+	for _, passthrough := range c.passthrough {
+		if strings.HasSuffix(passthroughQuestionName, passthrough) {
+			shouldPassthrough = true
+			break
 		}
 	}
+	if shouldPassthrough {
+		numServers := len(c.bootstrap)
+		upstream := c.bootstrap[rand.Intn(numServers)]
+		log.Printf("Request \"%s %s %s\" is passed through %s.\n", questionName, questionClass, questionType, upstream)
+		var reply *dns.Msg
+		var err error
+		if !isTCP {
+			reply, _, err = c.udpClient.Exchange(r, upstream)
+		} else {
+			reply, _, err = c.tcpClient.Exchange(r, upstream)
+		}
+		if err == nil {
+			w.WriteMsg(reply)
+			return
+		}
+		log.Println(err)
+		reply = jsonDNS.PrepareReply(r)
+		reply.Rcode = dns.RcodeServerFailure
+		w.WriteMsg(reply)
+		return
+	}
+
+	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(w, r, isTCP)
-	} else if requestType == "application/dns-message" {
-		req = c.generateRequestIETF(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.err != nil {
+		if urlErr, ok := req.err.(*url.Error); ok {
+			// should we only check timeout?
+			if urlErr.Timeout() {
+				c.selector.ReportUpstreamStatus(upstream, selector.Timeout)
+			}
+		}
+
 		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" {
-		c.parseResponseGoogle(w, r, isTCP, req)
-	} else if contentType == "application/dns-message" {
-		c.parseResponseIETF(w, r, isTCP, req)
-	} else {
-		panic("Unknown response Content-Type")
+	candidateType := strings.SplitN(req.response.Header.Get("Content-Type"), ";", 2)[0]
+
+	switch candidateType {
+	case "application/json":
+		c.parseResponseGoogle(ctx, w, r, isTCP, req)
+
+	case "application/dns-message", "application/dns-udpwireformat":
+		c.parseResponseIETF(ctx, w, r, isTCP, req)
+
+	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)
 	}
 }
 
@@ -264,7 +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"
@@ -29,20 +29,42 @@ import (
 	"github.com/BurntSushi/toml"
 )
 
-type config struct {
-	Listen         []string `toml:"listen"`
-	UpstreamGoogle []string `toml:"upstream_google"`
-	UpstreamIETF   []string `toml:"upstream_ietf"`
-	Bootstrap      []string `toml:"bootstrap"`
-	Timeout        uint     `toml:"timeout"`
-	NoCookies      bool     `toml:"no_cookies"`
-	NoECS          bool     `toml:"no_ecs"`
-	NoIPv6         bool     `toml:"no_ipv6"`
-	Verbose        bool     `toml:"verbose"`
+const (
+	Random   = "random"
+	NginxWRR = "weighted_round_robin"
+	LVSWRR   = "lvs_weighted_round_robin"
+)
+
+type upstreamDetail struct {
+	URL    string `toml:"url"`
+	Weight int32  `toml:"weight"`
 }
 
-func loadConfig(path string) (*config, error) {
-	conf := &config{}
+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"`
+	NoCookies        bool     `toml:"no_cookies"`
+	NoECS            bool     `toml:"no_ecs"`
+	NoIPv6           bool     `toml:"no_ipv6"`
+	Verbose          bool     `toml:"verbose"`
+	DebugHTTPHeaders []string `toml:"debug_http_headers"`
+}
+
+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
@@ -54,11 +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

@@ -4,43 +4,59 @@ listen = [
     "127.0.0.1:5380",
     "[::1]:53",
     "[::1]:5380",
+
+    ## To listen on both 0.0.0.0:53 and [::]:53, use the following line
+    # ":53",
 ]
 
 # 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 resolver, good ECS, good DNSSEC
+#[[upstream.upstream_ietf]]
+#    url = "https://dns.google/dns-query"
+#    weight = 50
 
-    # Google's experimental resolver, good ECS, good DNSSEC
-    #"https://dns.google.com/experimental",
+## CloudFlare's resolver, bad ECS, good DNSSEC
+## ECS is disabled for privacy by design: https://developers.cloudflare.com/1.1.1.1/nitty-gritty-details/#edns-client-subnet
+[[upstream.upstream_ietf]]
+    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
+## ECS is disabled for privacy by design: https://developers.cloudflare.com/1.1.1.1/nitty-gritty-details/#edns-client-subnet
+## Note that some ISPs have problems connecting to 1.1.1.1, try 1.0.0.1 if problems happen.
+#[[upstream.upstream_ietf]]
+#    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",
+## DNS.SB's resolver, good ECS, good DNSSEC
+## The provider claims no logging: https://dns.sb/doh/
+#[[upstream.upstream_ietf]]
+#    url = "https://doh.dns.sb/dns-query"
+#    weight = 50
 
-]
+## Quad9's resolver, bad ECS, good DNSSEC
+## ECS is disabled for privacy by design: https://www.quad9.net/faq/#What_is_EDNS_Client-Subnet
+#[[upstream.upstream_ietf]]
+#    url = "https://9.9.9.9/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/
+#[[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.
@@ -58,7 +74,25 @@ bootstrap = [
 
 ]
 
-# Timeout for upstream request
+# The domain names here are directly passed to bootstrap servers listed above,
+# allowing captive portal detection and systems without RTC to work.
+# Only effective if at least one bootstrap server is configured.
+passthrough = [
+    "captive.apple.com",
+    "connectivitycheck.gstatic.com",
+    "detectportal.firefox.com",
+    "msftconnecttest.com",
+    "nmcheck.gnome.org",
+
+    "pool.ntp.org",
+    "time.apple.com",
+    "time.asia.apple.com",
+    "time.euro.apple.com",
+    "time.nist.gov",
+    "time.windows.com",
+]
+
+# Timeout for upstream request in seconds
 timeout = 30
 
 # Disable HTTP Cookies

doh-client/google.go

@@ -24,48 +24,41 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"log"
-	"math/rand"
 	"net/http"
 	"net/url"
 	"strconv"
 	"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) generateRequestGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP bool) *DNSRequest {
-	reply := jsonDNS.PrepareReply(r)
-
-	if len(r.Question) != 1 {
-		log.Println("Number of questions is not 1")
-		reply.Rcode = dns.RcodeFormatError
+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
+	if questionClass != dns.ClassINET {
+		reply := jsonDNS.PrepareReply(r)
+		reply.Rcode = dns.RcodeRefused
 		w.WriteMsg(reply)
 		return &DNSRequest{
 			err: &dns.Error{},
 		}
 	}
-	question := &r.Question[0]
-	questionName := question.Name
 	questionType := ""
 	if qtype, ok := dns.TypeToString[question.Qtype]; ok {
 		questionType = qtype
 	} else {
-		questionType = strconv.Itoa(int(question.Qtype))
+		questionType = strconv.FormatUint(uint64(question.Qtype), 10)
 	}
 
-	if c.conf.Verbose {
-		fmt.Printf("%s - - [%s] \"%s IN %s\"\n", w.RemoteAddr(), time.Now().Format("02/Jan/2006:15:04:05 -0700"), questionName, questionType)
-	}
-
-	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"
@@ -81,28 +74,39 @@ func (c *Client) generateRequestGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP b
 		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)
 		reply.Rcode = dns.RcodeServerFailure
 		w.WriteMsg(reply)
 		return &DNSRequest{
 			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 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)
 		reply.Rcode = dns.RcodeServerFailure
 		w.WriteMsg(reply)
-		err1 := c.newHTTPClient()
-		if err1 != nil {
-			log.Fatalln(err1)
-		}
 		return &DNSRequest{
 			err: err,
 		}
@@ -110,16 +114,16 @@ func (c *Client) generateRequestGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP b
 
 	return &DNSRequest{
 		response:          resp,
-		reply:             reply,
+		reply:             jsonDNS.PrepareReply(r),
 		udpSize:           udpSize,
 		ednsClientAddress: ednsClientAddress,
 		ednsClientNetmask: ednsClientNetmask,
-		currentUpstream:   upstream,
+		currentUpstream:   upstream.URL,
 	}
 }
 
-func (c *Client) parseResponseGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
-	if req.response.StatusCode != 200 {
+func (c *Client) parseResponseGoogle(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
+	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

@@ -25,47 +25,22 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"encoding/base64"
 	"fmt"
 	"io/ioutil"
 	"log"
-	"math/rand"
 	"net"
 	"net/http"
-	"strconv"
 	"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(w dns.ResponseWriter, r *dns.Msg, isTCP bool) *DNSRequest {
-	reply := jsonDNS.PrepareReply(r)
-
-	if len(r.Question) != 1 {
-		log.Println("Number of questions is not 1")
-		reply.Rcode = dns.RcodeFormatError
-		w.WriteMsg(reply)
-		return &DNSRequest{
-			err: &dns.Error{},
-		}
-	}
-
-	question := &r.Question[0]
-	questionName := question.Name
-	questionType := ""
-	if qtype, ok := dns.TypeToString[question.Qtype]; ok {
-		questionType = qtype
-	} else {
-		questionType = strconv.Itoa(int(question.Qtype))
-	}
-
-	if c.conf.Verbose {
-		fmt.Printf("%s - - [%s] \"%s IN %s\"\n", w.RemoteAddr(), time.Now().Format("02/Jan/2006:15:04:05 -0700"), questionName, questionType)
-	}
-
-	question.Name = questionName
+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 {
@@ -115,6 +90,7 @@ func (c *Client) generateRequestIETF(w dns.ResponseWriter, r *dns.Msg, isTCP boo
 	requestBinary, err := r.Pack()
 	if err != nil {
 		log.Println(err)
+		reply := jsonDNS.PrepareReply(r)
 		reply.Rcode = dns.RcodeFormatError
 		w.WriteMsg(reply)
 		return &DNSRequest{
@@ -124,26 +100,27 @@ func (c *Client) generateRequestIETF(w dns.ResponseWriter, r *dns.Msg, isTCP boo
 	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-udpwireformat&dns=%s", upstream, requestBase64)
-	//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 {
-			// Do not respond, silently fail to prevent caching of SERVFAIL
 			log.Println(err)
+			reply := jsonDNS.PrepareReply(r)
+			reply.Rcode = dns.RcodeServerFailure
+			w.WriteMsg(reply)
 			return &DNSRequest{
 				err: err,
 			}
 		}
 	} else {
-		req, err = http.NewRequest("POST", upstream, bytes.NewReader(requestBinary))
+		req, err = http.NewRequest(http.MethodPost, upstream.URL, bytes.NewReader(requestBinary))
 		if err != nil {
-			// Do not respond, silently fail to prevent caching of SERVFAIL
 			log.Println(err)
+			reply := jsonDNS.PrepareReply(r)
+			reply.Rcode = dns.RcodeServerFailure
+			w.WriteMsg(reply)
 			return &DNSRequest{
 				err: err,
 			}
@@ -152,17 +129,25 @@ func (c *Client) generateRequestIETF(w dns.ResponseWriter, r *dns.Msg, isTCP boo
 	}
 	req.Header.Set("Accept", "application/dns-message, application/dns-udpwireformat, application/json")
 	req.Header.Set("User-Agent", USER_AGENT)
+	req = req.WithContext(ctx)
 	c.httpClientMux.RLock()
 	resp, err := c.httpClient.Do(req)
 	c.httpClientMux.RUnlock()
+
+	// 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)
 		reply.Rcode = dns.RcodeServerFailure
 		w.WriteMsg(reply)
-		err1 := c.newHTTPClient()
-		if err1 != nil {
-			log.Fatalln(err1)
-		}
 		return &DNSRequest{
 			err: err,
 		}
@@ -170,16 +155,16 @@ func (c *Client) generateRequestIETF(w dns.ResponseWriter, r *dns.Msg, isTCP boo
 
 	return &DNSRequest{
 		response:          resp,
-		reply:             reply,
+		reply:             jsonDNS.PrepareReply(r),
 		udpSize:           udpSize,
 		ednsClientAddress: ednsClientAddress,
 		ednsClientNetmask: ednsClientNetmask,
-		currentUpstream:   upstream,
+		currentUpstream:   upstream.URL,
 	}
 }
 
-func (c *Client) parseResponseIETF(w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
-	if req.response.StatusCode != 200 {
+func (c *Client) parseResponseIETF(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
+	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

@@ -25,21 +25,91 @@ package main
 
 import (
 	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
 	"log"
+	"os"
+	"runtime"
+	"strconv"
+
+	"github.com/m13253/dns-over-https/doh-client/config"
 )
 
+func checkPIDFile(pidFile string) (bool, error) {
+retry:
+	f, err := os.OpenFile(pidFile, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0666)
+	if os.IsExist(err) {
+		pidStr, err := ioutil.ReadFile(pidFile)
+		if err != nil {
+			return false, err
+		}
+		pid, err := strconv.ParseUint(string(pidStr), 10, 0)
+		if err != nil {
+			return false, err
+		}
+		_, err = os.Stat(fmt.Sprintf("/proc/%d", pid))
+		if os.IsNotExist(err) {
+			err = os.Remove(pidFile)
+			if err != nil {
+				return false, err
+			}
+			goto retry
+		} else if err != nil {
+			return false, err
+		}
+		log.Printf("Already running on PID %d, exiting.\n", pid)
+		return false, nil
+	} else if err != nil {
+		return false, err
+	}
+	defer f.Close()
+	_, err = io.WriteString(f, strconv.FormatInt(int64(os.Getpid()), 10))
+	if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
 func main() {
 	confPath := flag.String("conf", "doh-client.conf", "Configuration file")
 	verbose := flag.Bool("verbose", false, "Enable logging")
+	showVersion := flag.Bool("version", false, "Show software version and exit")
+	var pidFile *string
+
+	// I really want to push the technology forward by recommending cgroup-based
+	// process tracking. But I understand some cloud service providers have
+	// their own monitoring system. So this feature is only enabled on Linux and
+	// BSD series platforms which lacks functionality similar to cgroup.
+	switch runtime.GOOS {
+	case "dragonfly", "freebsd", "linux", "netbsd", "openbsd":
+		pidFile = flag.String("pid-file", "", "PID file for legacy supervision systems lacking support for reliable cgroup-based process tracking")
+	}
+
 	flag.Parse()
 
-	conf, err := loadConfig(*confPath)
+	if *showVersion {
+		fmt.Printf("doh-client %s\nHomepage: https://github.com/m13253/dns-over-https\n", VERSION)
+		return
+	}
+
+	if pidFile != nil && *pidFile != "" {
+		ok, err := checkPIDFile(*pidFile)
+		if err != nil {
+			log.Printf("Error checking PID file: %v\n", err)
+		}
+		if !ok {
+			return
+		}
+	}
+
+	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    = "1.3.9"
+	VERSION    = "2.1.2"
 	USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"
 )

doh-server/config.go

@@ -30,15 +30,18 @@ import (
 )
 
 type config struct {
-	Listen   []string `toml:"listen"`
-	Cert     string   `toml:"cert"`
-	Key      string   `toml:"key"`
-	Path     string   `toml:"path"`
-	Upstream []string `toml:"upstream"`
-	Timeout  uint     `toml:"timeout"`
-	Tries    uint     `toml:"tries"`
-	TCPOnly  bool     `toml:"tcp_only"`
-	Verbose  bool     `toml:"verbose"`
+	Listen           []string `toml:"listen"`
+	LocalAddr        string   `toml:"local_addr"`
+	Cert             string   `toml:"cert"`
+	Key              string   `toml:"key"`
+	Path             string   `toml:"path"`
+	Upstream         []string `toml:"upstream"`
+	Timeout          uint     `toml:"timeout"`
+	Tries            uint     `toml:"tries"`
+	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

@@ -2,8 +2,15 @@
 listen = [
     "127.0.0.1:8053",
     "[::1]:8053",
+
+    ## To listen on both 0.0.0.0:8053 and [::]:8053, use the following line
+    # ":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 +45,7 @@ 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/google.go

@@ -24,6 +24,7 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -38,7 +39,7 @@ import (
 	"golang.org/x/net/idna"
 )
 
-func (s *Server) parseRequestGoogle(w http.ResponseWriter, r *http.Request) *DNSRequest {
+func (s *Server) parseRequestGoogle(ctx context.Context, w http.ResponseWriter, r *http.Request) *DNSRequest {
 	name := r.FormValue("name")
 	if name == "" {
 		return &DNSRequest{
@@ -71,9 +72,9 @@ func (s *Server) parseRequestGoogle(w http.ResponseWriter, r *http.Request) *DNS
 
 	cdStr := r.FormValue("cd")
 	cd := false
-	if cdStr == "1" || cdStr == "true" {
+	if cdStr == "1" || strings.EqualFold(cdStr, "true") {
 		cd = true
-	} else if cdStr == "0" || cdStr == "false" || cdStr == "" {
+	} else if cdStr == "0" || strings.EqualFold(cdStr, "false") || cdStr == "" {
 	} else {
 		return &DNSRequest{
 			errcode: 400,
@@ -168,7 +169,7 @@ func (s *Server) parseRequestGoogle(w http.ResponseWriter, r *http.Request) *DNS
 	}
 }
 
-func (s *Server) generateResponseGoogle(w http.ResponseWriter, r *http.Request, req *DNSRequest) {
+func (s *Server) generateResponseGoogle(ctx context.Context, w http.ResponseWriter, r *http.Request, req *DNSRequest) {
 	respJSON := jsonDNS.Marshal(req.response)
 	respStr, err := json.Marshal(respJSON)
 	if err != nil {
@@ -184,9 +185,9 @@ func (s *Server) generateResponseGoogle(w http.ResponseWriter, r *http.Request,
 	w.Header().Set("Vary", "Accept")
 	if respJSON.HaveTTL {
 		if req.isTailored {
-			w.Header().Set("Cache-Control", "private, max-age="+strconv.Itoa(int(respJSON.LeastTTL)))
+			w.Header().Set("Cache-Control", "private, max-age="+strconv.FormatUint(uint64(respJSON.LeastTTL), 10))
 		} else {
-			w.Header().Set("Cache-Control", "public, max-age="+strconv.Itoa(int(respJSON.LeastTTL)))
+			w.Header().Set("Cache-Control", "public, max-age="+strconv.FormatUint(uint64(respJSON.LeastTTL), 10))
 		}
 		w.Header().Set("Expires", respJSON.EarliestExpires.Format(http.TimeFormat))
 	}

doh-server/ietf.go

@@ -25,10 +25,12 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"encoding/base64"
 	"fmt"
 	"io/ioutil"
 	"log"
+	"net"
 	"net/http"
 	"strconv"
 	"strings"
@@ -38,7 +40,7 @@ import (
 	"github.com/miekg/dns"
 )
 
-func (s *Server) parseRequestIETF(w http.ResponseWriter, r *http.Request) *DNSRequest {
+func (s *Server) parseRequestIETF(ctx context.Context, w http.ResponseWriter, r *http.Request) *DNSRequest {
 	requestBase64 := r.FormValue("dns")
 	requestBinary, err := base64.RawURLEncoding.DecodeString(requestBase64)
 	if err != nil {
@@ -85,15 +87,23 @@ func (s *Server) parseRequestIETF(w http.ResponseWriter, r *http.Request) *DNSRe
 		if qclass, ok := dns.ClassToString[question.Qclass]; ok {
 			questionClass = qclass
 		} else {
-			questionClass = strconv.Itoa(int(question.Qclass))
+			questionClass = strconv.FormatUint(uint64(question.Qclass), 10)
 		}
 		questionType := ""
 		if qtype, ok := dns.TypeToString[question.Qtype]; ok {
 			questionType = qtype
 		} else {
-			questionType = strconv.Itoa(int(question.Qtype))
+			questionType = strconv.FormatUint(uint64(question.Qtype), 10)
+		}
+		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)
 		}
-		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
@@ -145,7 +155,7 @@ func (s *Server) parseRequestIETF(w http.ResponseWriter, r *http.Request) *DNSRe
 	}
 }
 
-func (s *Server) generateResponseIETF(w http.ResponseWriter, r *http.Request, req *DNSRequest) {
+func (s *Server) generateResponseIETF(ctx context.Context, w http.ResponseWriter, r *http.Request, req *DNSRequest) {
 	respJSON := jsonDNS.Marshal(req.response)
 	req.response.Id = req.transactionID
 	respBytes, err := req.response.Pack()
@@ -165,9 +175,9 @@ func (s *Server) generateResponseIETF(w http.ResponseWriter, r *http.Request, re
 
 	if respJSON.HaveTTL {
 		if req.isTailored {
-			w.Header().Set("Cache-Control", "private, max-age="+strconv.Itoa(int(respJSON.LeastTTL)))
+			w.Header().Set("Cache-Control", "private, max-age="+strconv.FormatUint(uint64(respJSON.LeastTTL), 10))
 		} else {
-			w.Header().Set("Cache-Control", "public, max-age="+strconv.Itoa(int(respJSON.LeastTTL)))
+			w.Header().Set("Cache-Control", "public, max-age="+strconv.FormatUint(uint64(respJSON.LeastTTL), 10))
 		}
 		w.Header().Set("Expires", respJSON.EarliestExpires.Format(http.TimeFormat))
 	}

doh-server/main.go

@@ -25,14 +25,82 @@ package main
 
 import (
 	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
 	"log"
+	"os"
+	"runtime"
+	"strconv"
 )
 
+func checkPIDFile(pidFile string) (bool, error) {
+retry:
+	f, err := os.OpenFile(pidFile, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0666)
+	if os.IsExist(err) {
+		pidStr, err := ioutil.ReadFile(pidFile)
+		if err != nil {
+			return false, err
+		}
+		pid, err := strconv.ParseUint(string(pidStr), 10, 0)
+		if err != nil {
+			return false, err
+		}
+		_, err = os.Stat(fmt.Sprintf("/proc/%d", pid))
+		if os.IsNotExist(err) {
+			err = os.Remove(pidFile)
+			if err != nil {
+				return false, err
+			}
+			goto retry
+		} else if err != nil {
+			return false, err
+		}
+		log.Printf("Already running on PID %d, exiting.\n", pid)
+		return false, nil
+	} else if err != nil {
+		return false, err
+	}
+	defer f.Close()
+	_, err = io.WriteString(f, strconv.FormatInt(int64(os.Getpid()), 10))
+	if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
 func main() {
 	confPath := flag.String("conf", "doh-server.conf", "Configuration file")
 	verbose := flag.Bool("verbose", false, "Enable logging")
+	showVersion := flag.Bool("version", false, "Show software version and exit")
+	var pidFile *string
+
+	// I really want to push the technology forward by recommending cgroup-based
+	// process tracking. But I understand some cloud service providers have
+	// their own monitoring system. So this feature is only enabled on Linux and
+	// BSD series platforms which lacks functionality similar to cgroup.
+	switch runtime.GOOS {
+	case "dragonfly", "freebsd", "linux", "netbsd", "openbsd":
+		pidFile = flag.String("pid-file", "", "PID file for legacy supervision systems lacking support for reliable cgroup-based process tracking")
+	}
+
 	flag.Parse()
 
+	if *showVersion {
+		fmt.Printf("doh-server %s\nHomepage: https://github.com/m13253/dns-over-https\n", VERSION)
+		return
+	}
+
+	if pidFile != nil && *pidFile != "" {
+		ok, err := checkPIDFile(*pidFile)
+		if err != nil {
+			log.Printf("Error checking PID file: %v\n", err)
+		}
+		if !ok {
+			return
+		}
+	}
+
 	conf, err := loadConfig(*confPath)
 	if err != nil {
 		log.Fatalln(err)
@@ -42,6 +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

@@ -24,6 +24,7 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"math/rand"
@@ -55,22 +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 {
@@ -105,13 +125,31 @@ func (s *Server) Start() error {
 }
 
 func (s *Server) handlerFunc(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+
+	w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
+	w.Header().Set("Access-Control-Allow-Methods", "GET, HEAD, OPTIONS, POST")
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Access-Control-Max-Age", "3600")
 	w.Header().Set("Server", USER_AGENT)
 	w.Header().Set("X-Powered-By", USER_AGENT)
 
+	if r.Method == "OPTIONS" {
+		w.Header().Set("Content-Length", "0")
+		return
+	}
+
 	if r.Form == nil {
 		const maxMemory = 32 << 20 // 32 MB
 		r.ParseMultipartForm(maxMemory)
 	}
+
+	for _, header := range s.conf.DebugHTTPHeaders {
+		if value := r.Header.Get(header); value != "" {
+			log.Printf("%s: %s\n", header, value)
+		}
+	}
+
 	contentType := r.Header.Get("Content-Type")
 	if ct := r.FormValue("ct"); ct != "" {
 		contentType = ct
@@ -151,11 +189,11 @@ func (s *Server) handlerFunc(w http.ResponseWriter, r *http.Request) {
 
 	var req *DNSRequest
 	if contentType == "application/dns-json" {
-		req = s.parseRequestGoogle(w, r)
+		req = s.parseRequestGoogle(ctx, w, r)
 	} else if contentType == "application/dns-message" {
-		req = s.parseRequestIETF(w, r)
+		req = s.parseRequestIETF(ctx, w, r)
 	} else if contentType == "application/dns-udpwireformat" {
-		req = s.parseRequestIETF(w, r)
+		req = s.parseRequestIETF(ctx, w, r)
 	} else {
 		jsonDNS.FormatError(w, fmt.Sprintf("Invalid argument value: \"ct\" = %q", contentType), 415)
 		return
@@ -171,16 +209,16 @@ func (s *Server) handlerFunc(w http.ResponseWriter, r *http.Request) {
 	req = s.patchRootRD(req)
 
 	var err error
-	req, err = s.doDNSQuery(req)
+	req, err = s.doDNSQuery(ctx, req)
 	if err != nil {
 		jsonDNS.FormatError(w, fmt.Sprintf("DNS query failure (%s)", err.Error()), 503)
 		return
 	}
 
 	if responseType == "application/json" {
-		s.generateResponseGoogle(w, r, req)
+		s.generateResponseGoogle(ctx, w, r, req)
 	} else if responseType == "application/dns-message" {
-		s.generateResponseIETF(w, r, req)
+		s.generateResponseIETF(ctx, w, r, req)
 	} else {
 		panic("Unknown response Content-Type")
 	}
@@ -225,18 +263,38 @@ func (s *Server) patchRootRD(req *DNSRequest) *DNSRequest {
 	return req
 }
 
-func (s *Server) doDNSQuery(req *DNSRequest) (resp *DNSRequest, err error) {
+// Return the position index for the question of qtype from a DNS msg, otherwise return -1
+func (s *Server) indexQuestionType(msg *dns.Msg, qtype uint16) int {
+	for i, question := range msg.Question {
+		if question.Qtype == qtype {
+			return i
+		}
+	}
+	return -1
+}
+
+func (s *Server) doDNSQuery(ctx context.Context, req *DNSRequest) (resp *DNSRequest, err error) {
+	// TODO(m13253): Make ctx work. Waiting for a patch for ExchangeContext from miekg/dns.
 	numServers := len(s.conf.Upstream)
 	for i := uint(0); i < s.conf.Tries; i++ {
 		req.currentUpstream = s.conf.Upstream[rand.Intn(numServers)]
-		if !s.conf.TCPOnly {
+
+		// Use TCP if always configured to or if the Query type dictates it (AXFR)
+		if s.conf.TCPOnly || (s.indexQuestionType(req.request, dns.TypeAXFR) > -1) {
+			req.response, _, err = s.tcpClient.Exchange(req.request, req.currentUpstream)
+		} else {
 			req.response, _, err = s.udpClient.Exchange(req.request, req.currentUpstream)
-			if err == dns.ErrTruncated {
+			if err == nil && req.response != nil && req.response.Truncated {
 				log.Println(err)
 				req.response, _, err = s.tcpClient.Exchange(req.request, req.currentUpstream)
 			}
-		} else {
-			req.response, _, err = s.tcpClient.Exchange(req.request, req.currentUpstream)
+
+			// Retry with TCP if this was an IXFR request and we only received an SOA
+			if (s.indexQuestionType(req.request, dns.TypeIXFR) > -1) &&
+				(len(req.response.Answer) == 1) &&
+				(req.response.Answer[0].Header().Rrtype == dns.TypeSOA) {
+				req.response, _, err = s.tcpClient.Exchange(req.request, req.currentUpstream)
+			}
 		}
 		if err == nil {
 			return req, nil

doh-server/version.go

@@ -24,6 +24,6 @@
 package main
 
 const (
-	VERSION    = "1.3.9"
+	VERSION    = "2.1.2"
 	USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"
 )

go.mod

@@ -0,0 +1,12 @@
+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 v1.1.14
+	golang.org/x/crypto v0.0.0-20190621222207-cc06ce4a13d4 // indirect
+	golang.org/x/net v0.0.0-20190620200207-3b0461eec859
+	golang.org/x/sys v0.0.0-20190621203818-d432491b9138 // indirect
+)

go.sum

@@ -0,0 +1,18 @@
+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 v1.1.14 h1:wkQWn9wIp4mZbwW8XV6Km6owkvRPbOiV004ZM2CkGvA=
+github.com/miekg/dns v1.1.14/go.mod h1:W1PPwlIAgtquWBMBEV9nkV9Cazfe8ScdGz/Lj7v3Nrg=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20190621222207-cc06ce4a13d4 h1:ydJNl0ENAG67pFbB+9tfhiL2pYqLhfoaZFw/cjLhY4A=
+golang.org/x/crypto v0.0.0-20190621222207-cc06ce4a13d4/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859 h1:R/3boaszxrf1GEUWTVDzSKVwLmSJpwZ1yqXm8j0v2QI=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190621203818-d432491b9138 h1:t8BZD9RDjkm9/h7yYN6kE8oaeov5r9aztkB7zKA5Tkg=
+golang.org/x/sys v0.0.0-20190621203818-d432491b9138/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=

json-dns/marshal.go

@@ -90,7 +90,7 @@ func Marshal(msg *dns.Msg) *Response {
 					} else if ipv4 := clientAddress.To4(); ipv4 != nil {
 						clientAddress = ipv4
 					}
-					resp.EdnsClientSubnet = clientAddress.String() + "/" + strconv.Itoa(int(edns0.SourceScope))
+					resp.EdnsClientSubnet = clientAddress.String() + "/" + strconv.FormatUint(uint64(edns0.SourceScope), 10)
 				}
 			}
 			continue