April 1st is already over in some time zones :)

This reverts commit dac52ab42a.

dnscrypt-proxy/config.go

@@ -43,6 +43,7 @@ type Config struct {
 	SourceRequireDNSSEC   bool                       `toml:"require_dnssec"`
 	SourceRequireNoLog    bool                       `toml:"require_nolog"`
 	SourceRequireNoFilter bool                       `toml:"require_nofilter"`
+	SourceDNSCrypt        bool                       `toml:"dnscrypt_servers"`
 	SourceDoH             bool                       `toml:"doh_servers"`
 	SourceIPv4            bool                       `toml:"ipv4_servers"`
 	SourceIPv6            bool                       `toml:"ipv6_servers"`
@@ -71,6 +72,7 @@ func newConfig() Config {
 		SourceRequireNoFilter: true,
 		SourceIPv4:            true,
 		SourceIPv6:            false,
+		SourceDNSCrypt:        true,
 		SourceDoH:             true,
 		MaxClients:            250,
 		FallbackResolver:      DefaultFallbackResolver,
@@ -285,6 +287,7 @@ func ConfigLoad(proxy *Proxy, svcFlag *string) error {
 		config.SourceRequireNoLog = false
 		config.SourceIPv4 = true
 		config.SourceIPv6 = true
+		config.SourceDNSCrypt = true
 		config.SourceDoH = true
 	}
 
@@ -435,7 +438,8 @@ func (config *Config) loadSource(proxy *Proxy, requiredProps ServerInformalPrope
 				continue
 			}
 		}
-		if !(config.SourceDoH && registeredServer.stamp.proto == StampProtoTypeDoH) {
+		if !((config.SourceDNSCrypt && registeredServer.stamp.proto == StampProtoTypeDNSCrypt) ||
+			(config.SourceDoH && registeredServer.stamp.proto == StampProtoTypeDoH)) {
 			continue
 		}
 		dlog.Debugf("Adding [%s] to the set of wanted resolvers", registeredServer.name)

dnscrypt-proxy/dnscrypt_certs.go

@@ -0,0 +1,182 @@
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"strings"
+	"time"
+
+	"github.com/jedisct1/dlog"
+	"github.com/jedisct1/xsecretbox"
+	"github.com/miekg/dns"
+	"golang.org/x/crypto/ed25519"
+	"golang.org/x/crypto/nacl/box"
+)
+
+type CertInfo struct {
+	ServerPk           [32]byte
+	SharedKey          [32]byte
+	MagicQuery         [ClientMagicLen]byte
+	CryptoConstruction CryptoConstruction
+	ForwardSecurity    bool
+}
+
+func FetchCurrentDNSCryptCert(proxy *Proxy, serverName *string, proto string, pk ed25519.PublicKey, serverAddress string, providerName string, isNew bool) (CertInfo, int, error) {
+	if len(pk) != ed25519.PublicKeySize {
+		return CertInfo{}, 0, errors.New("Invalid public key length")
+	}
+	if !strings.HasSuffix(providerName, ".") {
+		providerName = providerName + "."
+	}
+	if serverName == nil {
+		serverName = &providerName
+	}
+	query := new(dns.Msg)
+	query.SetQuestion(providerName, dns.TypeTXT)
+	client := dns.Client{Net: proto, UDPSize: uint16(MaxDNSUDPPacketSize)}
+	in, rtt, err := client.Exchange(query, serverAddress)
+	if err != nil {
+		dlog.Noticef("[%s] TIMEOUT", *serverName)
+		return CertInfo{}, 0, err
+	}
+	now := uint32(time.Now().Unix())
+	certInfo := CertInfo{CryptoConstruction: UndefinedConstruction}
+	highestSerial := uint32(0)
+	for _, answerRr := range in.Answer {
+		binCert, err := packTxtString(strings.Join(answerRr.(*dns.TXT).Txt, ""))
+		if err != nil {
+			dlog.Warnf("[%v] Unable to unpack the certificate", providerName)
+			continue
+		}
+		if len(binCert) < 124 {
+			dlog.Warnf("[%v] Certificate too short", providerName)
+			continue
+		}
+		if !bytes.Equal(binCert[:4], CertMagic[:4]) {
+			dlog.Warnf("[%v] Invalid cert magic", providerName)
+			continue
+		}
+		cryptoConstruction := CryptoConstruction(0)
+		switch esVersion := binary.BigEndian.Uint16(binCert[4:6]); esVersion {
+		case 0x0001:
+			cryptoConstruction = XSalsa20Poly1305
+		case 0x0002:
+			cryptoConstruction = XChacha20Poly1305
+		default:
+			dlog.Noticef("[%v] Unsupported crypto construction", providerName)
+			continue
+		}
+		signature := binCert[8:72]
+		signed := binCert[72:]
+		if !ed25519.Verify(pk, signed, signature) {
+			dlog.Warnf("[%v] Incorrect signature", providerName)
+			continue
+		}
+		serial := binary.BigEndian.Uint32(binCert[112:116])
+		tsBegin := binary.BigEndian.Uint32(binCert[116:120])
+		tsEnd := binary.BigEndian.Uint32(binCert[120:124])
+		if tsBegin >= tsEnd {
+			dlog.Warnf("[%v] certificate ends before it starts (%v >= %v)", providerName, tsBegin, tsEnd)
+			continue
+		}
+		ttl := tsEnd - tsBegin
+		if ttl > 86400*7 {
+			dlog.Infof("[%v] the key validity period for this server is excessively long (%d days), significantly reducing reliability and forward security.", providerName, ttl/86400)
+			daysLeft := (tsEnd - now) / 86400
+			if daysLeft < 1 {
+				dlog.Criticalf("[%v] certificate will expire today -- Switch to a different resolver as soon as possible", providerName)
+			} else if daysLeft <= 7 {
+				dlog.Warnf("[%v] certificate is about to expire -- if you don't manage this server, tell the server operator about it", providerName)
+			} else if daysLeft <= 30 {
+				dlog.Infof("[%v] certificate will expire in %d days", providerName, daysLeft)
+			}
+			certInfo.ForwardSecurity = false
+		} else {
+			certInfo.ForwardSecurity = true
+		}
+		if !proxy.certIgnoreTimestamp {
+			if now > tsEnd || now < tsBegin {
+				dlog.Debugf("[%v] Certificate not valid at the current date", providerName)
+				continue
+			}
+		}
+		if serial < highestSerial {
+			dlog.Debugf("[%v] Superseded by a previous certificate", providerName)
+			continue
+		}
+		if serial == highestSerial {
+			if cryptoConstruction < certInfo.CryptoConstruction {
+				dlog.Debugf("[%v] Keeping the previous, preferred crypto construction", providerName)
+				continue
+			} else {
+				dlog.Debugf("[%v] Upgrading the construction from %v to %v", providerName, certInfo.CryptoConstruction, cryptoConstruction)
+			}
+		}
+		if cryptoConstruction != XChacha20Poly1305 && cryptoConstruction != XSalsa20Poly1305 {
+			dlog.Noticef("[%v] Cryptographic construction %v not supported", providerName, cryptoConstruction)
+			continue
+		}
+		var serverPk [32]byte
+		copy(serverPk[:], binCert[72:104])
+		var sharedKey [32]byte
+		if cryptoConstruction == XChacha20Poly1305 {
+			sharedKey, err = xsecretbox.SharedKey(proxy.proxySecretKey, serverPk)
+			if err != nil {
+				dlog.Criticalf("[%v] Weak public key", providerName)
+				continue
+			}
+		} else {
+			box.Precompute(&sharedKey, &serverPk, &proxy.proxySecretKey)
+		}
+		certInfo.SharedKey = sharedKey
+		highestSerial = serial
+		certInfo.CryptoConstruction = cryptoConstruction
+		copy(certInfo.ServerPk[:], serverPk[:])
+		copy(certInfo.MagicQuery[:], binCert[104:112])
+		if isNew {
+			dlog.Noticef("[%s] OK (crypto v%d) - rtt: %dms", *serverName, cryptoConstruction, rtt.Nanoseconds()/1000000)
+		} else {
+			dlog.Infof("[%s] OK (crypto v%d) - rtt: %dms", *serverName, cryptoConstruction, rtt.Nanoseconds()/1000000)
+		}
+	}
+	if certInfo.CryptoConstruction == UndefinedConstruction {
+		return certInfo, 0, errors.New("No useable certificate found")
+	}
+	return certInfo, int(rtt.Nanoseconds() / 1000000), nil
+}
+
+func isDigit(b byte) bool { return b >= '0' && b <= '9' }
+
+func dddToByte(s []byte) byte {
+	return byte((s[0]-'0')*100 + (s[1]-'0')*10 + (s[2] - '0'))
+}
+
+func packTxtString(s string) ([]byte, error) {
+	bs := make([]byte, len(s))
+	msg := make([]byte, 0)
+	copy(bs, s)
+	for i := 0; i < len(bs); i++ {
+		if bs[i] == '\\' {
+			i++
+			if i == len(bs) {
+				break
+			}
+			if i+2 < len(bs) && isDigit(bs[i]) && isDigit(bs[i+1]) && isDigit(bs[i+2]) {
+				msg = append(msg, dddToByte(bs[i:]))
+				i += 2
+			} else if bs[i] == 't' {
+				msg = append(msg, '\t')
+			} else if bs[i] == 'r' {
+				msg = append(msg, '\r')
+			} else if bs[i] == 'n' {
+				msg = append(msg, '\n')
+			} else {
+				msg = append(msg, bs[i])
+			}
+		} else {
+			msg = append(msg, bs[i])
+		}
+	}
+	return msg, nil
+}

dnscrypt-proxy/proxy.go

@@ -271,7 +271,22 @@ func (proxy *Proxy) processIncomingQuery(serverInfo *ServerInfo, clientProto str
 	}
 	if len(response) == 0 {
 		var ttl *uint32
-		if serverInfo.Proto == StampProtoTypeDoH {
+		if serverInfo.Proto == StampProtoTypeDNSCrypt {
+			encryptedQuery, clientNonce, err := proxy.Encrypt(serverInfo, query, serverProto)
+			if err != nil {
+				return
+			}
+			serverInfo.noticeBegin(proxy)
+			if serverProto == "udp" {
+				response, err = proxy.exchangeWithUDPServer(serverInfo, encryptedQuery, clientNonce)
+			} else {
+				response, err = proxy.exchangeWithTCPServer(serverInfo, encryptedQuery, clientNonce)
+			}
+			if err != nil {
+				serverInfo.noticeFailure(proxy)
+				return
+			}
+		} else if serverInfo.Proto == StampProtoTypeDoH {
 			tid := TransactionID(query)
 			SetTransactionID(query, 0)
 			serverInfo.noticeBegin(proxy)

dnscrypt-proxy/serversInfo.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"crypto/sha256"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -16,6 +17,7 @@ import (
 
 	"github.com/VividCortex/ewma"
 	"github.com/jedisct1/dlog"
+	"golang.org/x/crypto/ed25519"
 )
 
 const (
@@ -205,12 +207,49 @@ func (serversInfo *ServersInfo) getOne() *ServerInfo {
 }
 
 func (serversInfo *ServersInfo) fetchServerInfo(proxy *Proxy, name string, stamp ServerStamp, isNew bool) (ServerInfo, error) {
-	if stamp.proto == StampProtoTypeDoH {
+	if stamp.proto == StampProtoTypeDNSCrypt {
+		return serversInfo.fetchDNSCryptServerInfo(proxy, name, stamp, isNew)
+	} else if stamp.proto == StampProtoTypeDoH {
 		return serversInfo.fetchDoHServerInfo(proxy, name, stamp, isNew)
 	}
 	return ServerInfo{}, errors.New("Unsupported protocol")
 }
 
+func (serversInfo *ServersInfo) fetchDNSCryptServerInfo(proxy *Proxy, name string, stamp ServerStamp, isNew bool) (ServerInfo, error) {
+	if len(stamp.serverPk) != ed25519.PublicKeySize {
+		serverPk, err := hex.DecodeString(strings.Replace(string(stamp.serverPk), ":", "", -1))
+		if err != nil || len(serverPk) != ed25519.PublicKeySize {
+			dlog.Fatalf("Unsupported public key for [%s]: [%s]", name, stamp.serverPk)
+		}
+		dlog.Warnf("Public key [%s] shouldn't be hex-encoded any more", string(stamp.serverPk))
+		stamp.serverPk = serverPk
+	}
+	certInfo, rtt, err := FetchCurrentDNSCryptCert(proxy, &name, proxy.mainProto, stamp.serverPk, stamp.serverAddrStr, stamp.providerName, isNew)
+	if err != nil {
+		return ServerInfo{}, err
+	}
+	remoteUDPAddr, err := net.ResolveUDPAddr("udp", stamp.serverAddrStr)
+	if err != nil {
+		return ServerInfo{}, err
+	}
+	remoteTCPAddr, err := net.ResolveTCPAddr("tcp", stamp.serverAddrStr)
+	if err != nil {
+		return ServerInfo{}, err
+	}
+	return ServerInfo{
+		Proto:              StampProtoTypeDNSCrypt,
+		MagicQuery:         certInfo.MagicQuery,
+		ServerPk:           certInfo.ServerPk,
+		SharedKey:          certInfo.SharedKey,
+		CryptoConstruction: certInfo.CryptoConstruction,
+		Name:               name,
+		Timeout:            proxy.timeout,
+		UDPAddr:            remoteUDPAddr,
+		TCPAddr:            remoteTCPAddr,
+		initialRtt:         rtt,
+	}, nil
+}
+
 func (serversInfo *ServersInfo) fetchDoHServerInfo(proxy *Proxy, name string, stamp ServerStamp, isNew bool) (ServerInfo, error) {
 	if len(stamp.serverAddrStr) > 0 {
 		addrStr := stamp.serverAddrStr

dnscrypt-proxy/sources.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/csv"
 	"errors"
 	"fmt"
 	"io"
@@ -208,13 +209,58 @@ func NewSource(xTransport *XTransport, urls []string, minisignKeyStr string, cac
 }
 
 func (source *Source) Parse(prefix string) ([]RegisteredServer, error) {
-	if source.format == SourceFormatV2 {
+	if source.format == SourceFormatV1 {
+		return source.parseV1(prefix)
+	} else if source.format == SourceFormatV2 {
 		return source.parseV2(prefix)
 	}
 	dlog.Fatal("Unexpected source format")
 	return []RegisteredServer{}, nil
 }
 
+func (source *Source) parseV1(prefix string) ([]RegisteredServer, error) {
+	var registeredServers []RegisteredServer
+
+	csvReader := csv.NewReader(strings.NewReader(source.in))
+	records, err := csvReader.ReadAll()
+	if err != nil {
+		return registeredServers, nil
+	}
+	for lineNo, record := range records {
+		if len(record) == 0 {
+			continue
+		}
+		if len(record) < 14 {
+			return registeredServers, fmt.Errorf("Parse error at line %d", 1+lineNo)
+		}
+		if lineNo == 0 {
+			continue
+		}
+		name := prefix + record[0]
+		description := record[2]
+		serverAddrStr := record[10]
+		providerName := record[11]
+		serverPkStr := record[12]
+		props := ServerInformalProperties(0)
+		if strings.EqualFold(record[7], "yes") {
+			props |= ServerInformalPropertyDNSSEC
+		}
+		if strings.EqualFold(record[8], "yes") {
+			props |= ServerInformalPropertyNoLog
+		}
+		stamp, err := NewDNSCryptServerStampFromLegacy(serverAddrStr, serverPkStr, providerName, props)
+		if err != nil {
+			return registeredServers, err
+		}
+		registeredServer := RegisteredServer{
+			name: name, stamp: stamp, description: description,
+		}
+		dlog.Debugf("Registered [%s] with stamp [%s]", name, stamp.String())
+		registeredServers = append(registeredServers, registeredServer)
+	}
+	return registeredServers, nil
+}
+
 func (source *Source) parseV2(prefix string) ([]RegisteredServer, error) {
 	var registeredServers []RegisteredServer
 	in := string(source.in)

dnscrypt-proxy/stamps.go

@@ -3,6 +3,7 @@ package main
 import (
 	"encoding/base64"
 	"encoding/binary"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"net"
@@ -10,19 +11,23 @@ import (
 	"strings"
 
 	"github.com/jedisct1/dlog"
+	"golang.org/x/crypto/ed25519"
 )
 
 type StampProtoType uint8
 
 const (
-	StampProtoTypePlain = StampProtoType(0x00)
+	StampProtoTypePlain    = StampProtoType(0x00)
-	StampProtoTypeDoH   = StampProtoType(0x02)
+	StampProtoTypeDNSCrypt = StampProtoType(0x01)
+	StampProtoTypeDoH      = StampProtoType(0x02)
 )
 
 func (stampProtoType *StampProtoType) String() string {
 	switch *stampProtoType {
 	case StampProtoTypePlain:
 		return "Plain"
+	case StampProtoTypeDNSCrypt:
+		return "DNSCrypt"
 	case StampProtoTypeDoH:
 		return "DoH"
 	default:
@@ -40,6 +45,23 @@ type ServerStamp struct {
 	proto         StampProtoType
 }
 
+func NewDNSCryptServerStampFromLegacy(serverAddrStr string, serverPkStr string, providerName string, props ServerInformalProperties) (ServerStamp, error) {
+	if net.ParseIP(serverAddrStr) != nil {
+		serverAddrStr = fmt.Sprintf("%s:%d", serverAddrStr, DefaultPort)
+	}
+	serverPk, err := hex.DecodeString(strings.Replace(serverPkStr, ":", "", -1))
+	if err != nil || len(serverPk) != ed25519.PublicKeySize {
+		return ServerStamp{}, fmt.Errorf("Unsupported public key: [%s]", serverPkStr)
+	}
+	return ServerStamp{
+		serverAddrStr: serverAddrStr,
+		serverPk:      serverPk,
+		providerName:  providerName,
+		props:         props,
+		proto:         StampProtoTypeDNSCrypt,
+	}, nil
+}
+
 func NewServerStampFromString(stampStr string) (ServerStamp, error) {
 	if !strings.HasPrefix(stampStr, "sdns://") && !strings.HasPrefix(stampStr, "dnsc://") {
 		return ServerStamp{}, errors.New("Stamps are expected to start with sdns://")
@@ -51,12 +73,58 @@ func NewServerStampFromString(stampStr string) (ServerStamp, error) {
 	if len(bin) < 1 {
 		return ServerStamp{}, errors.New("Stamp is too short")
 	}
-	if bin[0] == uint8(StampProtoTypeDoH) {
+	if bin[0] == uint8(StampProtoTypeDNSCrypt) {
+		return newDNSCryptServerStamp(bin)
+	} else if bin[0] == uint8(StampProtoTypeDoH) {
 		return newDoHServerStamp(bin)
 	}
 	return ServerStamp{}, errors.New("Unsupported stamp version or protocol")
 }
 
+// id(u8)=0x01 props addrLen(1) serverAddr pkStrlen(1) pkStr providerNameLen(1) providerName
+
+func newDNSCryptServerStamp(bin []byte) (ServerStamp, error) {
+	stamp := ServerStamp{proto: StampProtoTypeDNSCrypt}
+	if len(bin) < 66 {
+		return stamp, errors.New("Stamp is too short")
+	}
+	stamp.props = ServerInformalProperties(binary.LittleEndian.Uint64(bin[1:9]))
+	binLen := len(bin)
+	pos := 9
+
+	len := int(bin[pos])
+	if 1+len >= binLen-pos {
+		return stamp, errors.New("Invalid stamp")
+	}
+	pos++
+	stamp.serverAddrStr = string(bin[pos : pos+len])
+	pos += len
+	if net.ParseIP(strings.TrimRight(strings.TrimLeft(stamp.serverAddrStr, "["), "]")) != nil {
+		stamp.serverAddrStr = fmt.Sprintf("%s:%d", stamp.serverAddrStr, DefaultPort)
+	}
+
+	len = int(bin[pos])
+	if 1+len >= binLen-pos {
+		return stamp, errors.New("Invalid stamp")
+	}
+	pos++
+	stamp.serverPk = bin[pos : pos+len]
+	pos += len
+
+	len = int(bin[pos])
+	if len >= binLen-pos {
+		return stamp, errors.New("Invalid stamp")
+	}
+	pos++
+	stamp.providerName = string(bin[pos : pos+len])
+	pos += len
+
+	if pos != binLen {
+		return stamp, errors.New("Invalid stamp (garbage after end)")
+	}
+	return stamp, nil
+}
+
 // id(u8)=0x02 props addrLen(1) serverAddr hashLen(1) hash providerNameLen(1) providerName pathLen(1) path
 
 func newDoHServerStamp(bin []byte) (ServerStamp, error) {
@@ -120,13 +188,38 @@ func newDoHServerStamp(bin []byte) (ServerStamp, error) {
 }
 
 func (stamp *ServerStamp) String() string {
-	if stamp.proto == StampProtoTypeDoH {
+	if stamp.proto == StampProtoTypeDNSCrypt {
+		return stamp.dnsCryptString()
+	} else if stamp.proto == StampProtoTypeDoH {
 		return stamp.dohString()
 	}
 	dlog.Fatal("Unsupported protocol")
 	return ""
 }
 
+func (stamp *ServerStamp) dnsCryptString() string {
+	bin := make([]uint8, 9)
+	bin[0] = uint8(StampProtoTypeDNSCrypt)
+	binary.LittleEndian.PutUint64(bin[1:9], uint64(stamp.props))
+
+	serverAddrStr := stamp.serverAddrStr
+	if strings.HasSuffix(serverAddrStr, ":"+strconv.Itoa(DefaultPort)) {
+		serverAddrStr = serverAddrStr[:len(serverAddrStr)-1-len(strconv.Itoa(DefaultPort))]
+	}
+	bin = append(bin, uint8(len(serverAddrStr)))
+	bin = append(bin, []uint8(serverAddrStr)...)
+
+	bin = append(bin, uint8(len(stamp.serverPk)))
+	bin = append(bin, stamp.serverPk...)
+
+	bin = append(bin, uint8(len(stamp.providerName)))
+	bin = append(bin, []uint8(stamp.providerName)...)
+
+	str := base64.RawURLEncoding.EncodeToString(bin)
+
+	return "sdns://" + str
+}
+
 func (stamp *ServerStamp) dohString() string {
 	bin := make([]uint8, 9)
 	bin[0] = uint8(StampProtoTypeDoH)