Release 1.4.2

Refine runtime.GOOS check, use switch case to replace a long if

Changelog.md

@@ -4,6 +4,22 @@ This Changelog records major changes between versions.
 
 Not all changes are recorded. Please check git log for details.
 
+## 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

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
 

darwin-wrapper/Makefile

@@ -6,7 +6,7 @@ PREFIX = /usr/local
 all: doh-logger
 
 doh-logger: doh-logger.swift
-	$(SWIFTC) -o $@ -O $<
+	$(SWIFTC) -o $@ -O -static-stdlib $<
 
 clean:
 	rm -f doh-logger

doh-client/client.go

@@ -25,11 +25,13 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"log"
 	"math/rand"
 	"net"
 	"net/http"
 	"net/http/cookiejar"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -37,11 +39,15 @@ import (
 	"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
 	bootstrap            []string
+	passthrough          []string
+	udpClient            *dns.Client
+	tcpClient            *dns.Client
 	udpServers           []*dns.Server
 	tcpServers           []*dns.Server
 	bootstrapResolver    *net.Resolver
@@ -69,6 +75,15 @@ func NewClient(conf *config) (c *Client, err error) {
 
 	udpHandler := dns.HandlerFunc(c.udpHandlerFunc)
 	tcpHandler := dns.HandlerFunc(c.tcpHandlerFunc)
+	c.udpClient = &dns.Client{
+		Net:     "udp",
+		UDPSize: dns.DefaultMsgSize,
+		Timeout: time.Duration(conf.Timeout) * time.Second,
+	}
+	c.tcpClient = &dns.Client{
+		Net:     "tcp",
+		Timeout: time.Duration(conf.Timeout) * time.Second,
+	}
 	for _, addr := range conf.Listen {
 		c.udpServers = append(c.udpServers, &dns.Server{
 			Addr:    addr,
@@ -105,6 +120,15 @@ 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 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,
@@ -114,7 +138,10 @@ func NewClient(conf *config) (c *Client, err error) {
 		if err != nil {
 			return nil, err
 		}
+	} else {
+		c.cookieJar = nil
 	}
+
 	c.httpClientMux = new(sync.RWMutex)
 	err = c.newHTTPClient()
 	if err != nil {
@@ -126,7 +153,7 @@ func NewClient(conf *config) (c *Client, err error) {
 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.Timeout)*time.Second {
 		return nil
 	}
 	if c.httpTransport != nil {
@@ -145,7 +172,6 @@ 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,
 	}
 	if c.conf.NoIPv6 {
@@ -191,11 +217,73 @@ func (c *Client) Start() error {
 }
 
 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.Timeout)*time.Second)
+	defer cancel()
+
+	if r.Response {
 		log.Println("Received a response packet")
 		return
 	}
 
+	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 {
+		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.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
+	}
+
 	requestType := ""
 	if len(c.conf.UpstreamIETF) == 0 {
 		requestType = "application/dns-json"
@@ -213,13 +301,21 @@ func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
 
 	var req *DNSRequest
 	if requestType == "application/dns-json" {
-		req = c.generateRequestGoogle(w, r, isTCP)
+		req = c.generateRequestGoogle(ctx, w, r, isTCP)
 	} else if requestType == "application/dns-message" {
-		req = c.generateRequestIETF(w, r, isTCP)
+		req = c.generateRequestIETF(ctx, w, r, isTCP)
 	} else {
 		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 {
 		return
 	}
@@ -241,9 +337,9 @@ func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
 	}
 
 	if contentType == "application/json" {
-		c.parseResponseGoogle(w, r, isTCP, req)
+		c.parseResponseGoogle(ctx, w, r, isTCP, req)
 	} else if contentType == "application/dns-message" {
-		c.parseResponseIETF(w, r, isTCP, req)
+		c.parseResponseIETF(ctx, w, r, isTCP, req)
 	} else {
 		panic("Unknown response Content-Type")
 	}

doh-client/config.go

@@ -30,15 +30,17 @@ import (
 )
 
 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"`
+	Listen           []string `toml:"listen"`
+	UpstreamGoogle   []string `toml:"upstream_google"`
+	UpstreamIETF     []string `toml:"upstream_ietf"`
+	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"`
 }
 
 func loadConfig(path string) (*config, error) {

doh-client/doh-client.conf

@@ -58,6 +58,24 @@ bootstrap = [
 
 ]
 
+# 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
 timeout = 30
 

doh-client/google.go

@@ -24,6 +24,7 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -33,34 +34,28 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
-	"time"
 
 	"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) *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))
-	}
-
-	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)
+		questionType = strconv.FormatUint(uint64(question.Qtype), 10)
 	}
 
 	numServers := len(c.conf.UpstreamGoogle)
@@ -84,6 +79,7 @@ func (c *Client) generateRequestGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP b
 	req, err := http.NewRequest("GET", requestURL, nil)
 	if err != nil {
 		log.Println(err)
+		reply := jsonDNS.PrepareReply(r)
 		reply.Rcode = dns.RcodeServerFailure
 		w.WriteMsg(reply)
 		return &DNSRequest{
@@ -92,17 +88,22 @@ func (c *Client) generateRequestGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP b
 	}
 	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 {
+		// 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,
 		}
@@ -110,7 +111,7 @@ 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,
@@ -118,7 +119,7 @@ func (c *Client) generateRequestGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP b
 	}
 }
 
-func (c *Client) parseResponseGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
+func (c *Client) parseResponseGoogle(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
 	if req.response.StatusCode != 200 {
 		log.Printf("HTTP error from upstream %s: %s\n", req.currentUpstream, req.response.Status)
 		req.reply.Rcode = dns.RcodeServerFailure

doh-client/ietf.go

@@ -25,6 +25,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"encoding/base64"
 	"fmt"
 	"io/ioutil"
@@ -32,7 +33,6 @@ import (
 	"math/rand"
 	"net"
 	"net/http"
-	"strconv"
 	"strings"
 	"time"
 
@@ -40,32 +40,7 @@ import (
 	"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) *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{
@@ -132,8 +108,10 @@ func (c *Client) generateRequestIETF(w dns.ResponseWriter, r *dns.Msg, isTCP boo
 	if len(requestURL) < 2048 {
 		req, err = http.NewRequest("GET", 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,
 			}
@@ -141,8 +119,10 @@ func (c *Client) generateRequestIETF(w dns.ResponseWriter, r *dns.Msg, isTCP boo
 	} else {
 		req, err = http.NewRequest("POST", upstream, 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,
 			}
@@ -151,17 +131,22 @@ 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 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,
 		}
@@ -169,7 +154,7 @@ 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,
@@ -177,7 +162,7 @@ func (c *Client) generateRequestIETF(w dns.ResponseWriter, r *dns.Msg, isTCP boo
 	}
 }
 
-func (c *Client) parseResponseIETF(w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
+func (c *Client) parseResponseIETF(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
 	if req.response.StatusCode != 200 {
 		log.Printf("HTTP error from upstream %s: %s\n", req.currentUpstream, req.response.Status)
 		req.reply.Rcode = dns.RcodeServerFailure

doh-client/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-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()
 
+	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)

doh-client/version.go

@@ -24,6 +24,6 @@
 package main
 
 const (
-	VERSION    = "1.3.10"
+	VERSION    = "1.4.2"
 	USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"
 )

doh-server/config.go

@@ -30,15 +30,16 @@ 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"`
+	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"`
 }
 
 func loadConfig(path string) (*config, error) {

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

@@ -25,6 +25,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"encoding/base64"
 	"fmt"
 	"io/ioutil"
@@ -38,7 +39,7 @@ 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 {
@@ -85,13 +86,13 @@ 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)
 		}
 		fmt.Printf("%s - - [%s] \"%s %s %s\"\n", r.RemoteAddr, time.Now().Format("02/Jan/2006:15:04:05 -0700"), questionName, questionClass, questionType)
 	}
@@ -145,7 +146,7 @@ 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 +166,9 @@ 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)

doh-server/server.go

@@ -24,6 +24,7 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"math/rand"
@@ -105,13 +106,31 @@ 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 +170,11 @@ 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 +190,16 @@ 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")
 	}
@@ -225,13 +244,14 @@ func (s *Server) patchRootRD(req *DNSRequest) *DNSRequest {
 	return req
 }
 
-func (s *Server) doDNSQuery(req *DNSRequest) (resp *DNSRequest, err error) {
+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 {
 			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)
 			}

doh-server/version.go

@@ -24,6 +24,6 @@
 package main
 
 const (
-	VERSION    = "1.3.10"
+	VERSION    = "1.4.2"
 	USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"
 )

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