Preliminary implementation of stamps

dnscrypt-proxy/config.go

@@ -227,7 +227,7 @@ func ConfigLoad(proxy *Proxy, svcFlag *string, config_file string) error {
 		var stamp ServerStamp
 		var err error
 		if len(serverConfig.Stamp) > 0 {
-			dlog.Fatal("Stamps are not implemented yet")
+			stamp, err = NewServerStampFromString(serverConfig.Stamp)
 		} else {
 			props := ServerInformalProperties(0)
 			if serverConfig.DNSSEC {
@@ -237,9 +237,9 @@ func ConfigLoad(proxy *Proxy, svcFlag *string, config_file string) error {
 				props |= ServerInformalPropertyNoLog
 			}
 			stamp, err = NewServerStampFromLegacy(serverConfig.Address, serverConfig.PublicKey, serverConfig.ProviderName, props)
-			if err != nil {
-				return err
-			}
+		}
+		if err != nil {
+			return err
 		}
 		proxy.registeredServers = append(proxy.registeredServers,
 			RegisteredServer{name: serverName, stamp: stamp})

dnscrypt-proxy/dnscrypt-proxy.toml

@@ -205,6 +205,4 @@ format = 'tsv'
 
 [servers]
   [servers.'dnscrypt.org-fr']
-  provider_name = '2.dnscrypt-cert.fr.dnscrypt.org'
-  address = '212.47.228.136:443'
-  public_key = 'E801:B84E:A606:BFB0:BAC0:CE43:445B:B15E:BA64:B02F:A3C4:AA31:AE10:636A:0790:324D'
+  stamp = 'dnsc://AQMAAAAAAAAAEjIxMi40Ny4yMjguMTM2OjQ0M09FODAxOkI4NEU6QTYwNjpCRkIwOkJBQzA6Q0U0Mzo0NDVCOkIxNUU6QkE2NDpCMDJGOkEzQzQ6QUEzMTpBRTEwOjYzNkE6MDc5MDozMjREHzIuZG5zY3J5cHQtY2VydC5mci5kbnNjcnlwdC5vcmc'

dnscrypt-proxy/stamps.go

@@ -3,8 +3,10 @@ package main
 import (
 	"encoding/base64"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"net"
+	"strings"
 )
 
 type ServerStamp struct {
@@ -30,6 +32,50 @@ func NewServerStampFromLegacy(serverAddrStr string, serverPkStr string, provider
 
 func NewServerStampFromString(stampStr string) (ServerStamp, error) {
 	stamp := ServerStamp{}
+	if !strings.HasPrefix(stampStr, "dnsc://") {
+		return stamp, errors.New("Stamps are expected to start with dnsc://")
+	}
+	bin, err := base64.RawURLEncoding.DecodeString(stampStr[7:])
+	if err != nil {
+		return stamp, err
+	}
+	if len(bin) < 24 {
+		return stamp, errors.New("Stamp is too short")
+	}
+	if bin[0] != 0x01 {
+		return stamp, errors.New("Unsupported stamp version")
+	}
+	stamp.props = ServerInformalProperties(binary.LittleEndian.Uint64(bin[1:9]))
+	binLen := len(bin)
+	pos := 9
+
+	len := int(bin[pos])
+	if len >= binLen-pos {
+		return stamp, errors.New("Invalid stamp")
+	}
+	pos++
+	stamp.serverAddrStr = string(bin[pos : pos+len])
+	pos += len
+
+	len = int(bin[pos])
+	if len >= binLen-pos {
+		return stamp, errors.New("Invalid stamp")
+	}
+	pos++
+	stamp.serverPkStr = string(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
 }