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Code

Added Client.AdjustPayloadSize field and more tests

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This commit is contained in:
Andrey Meshkov 2018-12-18 13:03:57 +03:00
parent 1215bb8b15
commit 45e0327548
2 changed files with 85 additions and 30 deletions
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44
dnscrypt.go
View file

@ -41,22 +41,24 @@ var (
)
const (
clientMagicLen = 8
nonceSize = xsecretbox.NonceSize
halfNonceSize = xsecretbox.NonceSize / 2
tagSize = xsecretbox.TagSize
publicKeySize = 32
queryOverhead = clientMagicLen + publicKeySize + halfNonceSize + tagSize
responseOverhead = len(serverMagic) + nonceSize + tagSize
clientMagicLen = 8
nonceSize = xsecretbox.NonceSize
halfNonceSize = xsecretbox.NonceSize / 2
tagSize = xsecretbox.TagSize
publicKeySize = 32
queryOverhead = clientMagicLen + publicKeySize + halfNonceSize + tagSize
// <min-query-len> is a variable length, initially set to 256 bytes, and
// must be a multiple of 64 bytes. (see https://dnscrypt.info/protocol)
// Some servers do not work if padded length is less than 256. Example: Quad9
minUdpQuestionSize = 256
)
// Client contains parameters for a DNSCrypt client
type Client struct {
Proto string // Protocol ("udp" or "tcp")
Timeout time.Duration // Timeout for read/write operations
Proto string // Protocol ("udp" or "tcp"). Empty means "udp".
Timeout time.Duration // Timeout for read/write operations
AdjustPayloadSize bool // If true, the client will automatically add a EDNS0 RR that will advertise a larger buffer
}
// CertInfo contains DnsCrypt server certificate data retrieved from the server
@ -113,7 +115,12 @@ func (c *Client) DialStamp(stamp dnsstamps.ServerStamp) (*ServerInfo, time.Durat
curve25519.ScalarBaseMult(&serverInfo.PublicKey, &serverInfo.SecretKey)
// Set the provider properties
serverInfo.Proto = c.Proto
proto := c.Proto
if proto == "" {
proto = "udp"
}
serverInfo.Proto = proto
serverInfo.ServerPublicKey = stamp.ServerPk
serverInfo.ServerAddress = stamp.ServerAddrStr
serverInfo.ProviderName = stamp.ProviderName
@ -138,7 +145,7 @@ func (c *Client) DialStamp(stamp dnsstamps.ServerStamp) (*ServerInfo, time.Durat
func (c *Client) Exchange(m *dns.Msg, s *ServerInfo) (*dns.Msg, time.Duration, error) {
now := time.Now()
conn, err := net.Dial(c.Proto, s.ServerAddress)
conn, err := net.Dial(s.Proto, s.ServerAddress)
if err != nil {
return nil, 0, err
}
@ -158,7 +165,9 @@ func (c *Client) Exchange(m *dns.Msg, s *ServerInfo) (*dns.Msg, time.Duration, e
func (c *Client) ExchangeConn(m *dns.Msg, s *ServerInfo, conn net.Conn) (*dns.Msg, time.Duration, error) {
now := time.Now()
c.adjustPayloadSize(m)
if c.AdjustPayloadSize {
c.adjustPayloadSize(m)
}
query, err := m.Pack()
if err != nil {
return nil, 0, err
@ -213,21 +222,20 @@ func (c *Client) ExchangeConn(m *dns.Msg, s *ServerInfo, conn net.Conn) (*dns.Ms
// Adjusts the maximum payload size advertised in queries sent to upstream servers
// See https://github.com/jedisct1/dnscrypt-proxy/blob/master/dnscrypt-proxy/plugin_get_set_payload_size.go
// TODO: I don't really understand why it is required :)
// See here also: https://github.com/jedisct1/dnscrypt-proxy/issues/667
func (c *Client) adjustPayloadSize(msg *dns.Msg) {
originalMaxPayloadSize := 512 - responseOverhead
originalMaxPayloadSize := dns.MinMsgSize
edns0 := msg.IsEdns0()
dnssec := false
if edns0 != nil {
originalMaxPayloadSize = min(int(edns0.UDPSize())-responseOverhead, originalMaxPayloadSize)
originalMaxPayloadSize = int(edns0.UDPSize())
dnssec = edns0.Do()
}
var options *[]dns.EDNS0
maxPayloadSize := maxDNSUDPPacketSize - responseOverhead
maxPayloadSize = min(maxDNSUDPPacketSize-responseOverhead, max(originalMaxPayloadSize, maxPayloadSize))
maxPayloadSize := min(maxDNSUDPPacketSize, originalMaxPayloadSize)
if maxPayloadSize > 512 {
if maxPayloadSize > dns.MinMsgSize {
var extra2 []dns.RR
for _, extra := range msg.Extra {
if extra.Header().Rrtype != dns.TypeOPT {

71
dnscrypt_test.go
View file

@ -42,61 +42,108 @@ func TestParseStamp(t *testing.T) {
log.Println("")
}
func TestInvalidStamp(t *testing.T) {
client := Client{}
_, _, err := client.Dial("sdns://AQIAAAAAAAAAFDE")
if err == nil {
t.Fatalf("Dial must not have been possible")
}
}
func TestTimeoutOnDialError(t *testing.T) {
// AdGuard DNS pointing to a wrong IP
stampStr := "sdns://AQIAAAAAAAAADDguOC44Ljg6NTQ0MyDRK0fyUtzywrv4mRCG6vec5EldixbIoMQyLlLKPzkIcyIyLmRuc2NyeXB0LmRlZmF1bHQubnMxLmFkZ3VhcmQuY29t"
client := Client{Timeout: 300 * time.Millisecond}
_, _, err := client.Dial(stampStr)
if err == nil {
t.Fatalf("Dial must not have been possible")
}
if err, ok := err.(net.Error); !ok || !err.Timeout() {
t.Fatalf("Not the timeout error")
}
}
func TestTimeoutOnDialExchange(t *testing.T) {
// AdGuard DNS
stampStr := "sdns://AQIAAAAAAAAAFDE3Ni4xMDMuMTMwLjEzMDo1NDQzINErR_JS3PLCu_iZEIbq95zkSV2LFsigxDIuUso_OQhzIjIuZG5zY3J5cHQuZGVmYXVsdC5uczEuYWRndWFyZC5jb20"
client := Client{Timeout: 300 * time.Millisecond}
serverInfo, _, err := client.Dial(stampStr)
if err != nil {
t.Fatalf("Could not establish connection with %s", stampStr)
}
// Point it to an IP where there's no DNSCrypt server
serverInfo.ServerAddress = "8.8.8.8:5443"
req := dns.Msg{}
req.Id = dns.Id()
req.RecursionDesired = true
req.Question = []dns.Question{
{Name: "google-public-dns-a.google.com.", Qtype: dns.TypeA, Qclass: dns.ClassINET},
}
//
_, _, err = client.Exchange(&req, serverInfo)
if err == nil {
t.Fatalf("Exchange must not have been possible")
}
if err, ok := err.(net.Error); !ok || !err.Timeout() {
t.Fatalf("Not the timeout error")
}
}
func TestDnsCryptResolver(t *testing.T) {
stamps := []struct {
stampStr string
udp bool
}{
{
// AdGuard DNS
stampStr: "sdns://AQIAAAAAAAAAFDE3Ni4xMDMuMTMwLjEzMDo1NDQzINErR_JS3PLCu_iZEIbq95zkSV2LFsigxDIuUso_OQhzIjIuZG5zY3J5cHQuZGVmYXVsdC5uczEuYWRndWFyZC5jb20",
udp: true,
},
{
// AdGuard DNS Family
stampStr: "sdns://AQIAAAAAAAAAFDE3Ni4xMDMuMTMwLjEzMjo1NDQzILgxXdexS27jIKRw3C7Wsao5jMnlhvhdRUXWuMm1AFq6ITIuZG5zY3J5cHQuZmFtaWx5Lm5zMS5hZGd1YXJkLmNvbQ",
udp: true,
},
{
// Cisco OpenDNS
stampStr: "sdns://AQAAAAAAAAAADjIwOC42Ny4yMjAuMjIwILc1EUAgbyJdPivYItf9aR6hwzzI1maNDL4Ev6vKQ_t5GzIuZG5zY3J5cHQtY2VydC5vcGVuZG5zLmNvbQ",
udp: true,
},
{
// Cisco OpenDNS Family Shield
stampStr: "sdns://AQAAAAAAAAAADjIwOC42Ny4yMjAuMTIzILc1EUAgbyJdPivYItf9aR6hwzzI1maNDL4Ev6vKQ_t5GzIuZG5zY3J5cHQtY2VydC5vcGVuZG5zLmNvbQ",
udp: true,
},
{
// Quad9 (anycast) dnssec/no-log/filter 9.9.9.9
stampStr: "sdns://AQMAAAAAAAAADDkuOS45Ljk6ODQ0MyBnyEe4yHWM0SAkVUO-dWdG3zTfHYTAC4xHA2jfgh2GPhkyLmRuc2NyeXB0LWNlcnQucXVhZDkubmV0",
udp: true,
},
{
// https://securedns.eu/
stampStr: "sdns://AQcAAAAAAAAAEzE0Ni4xODUuMTY3LjQzOjUzNTMgs6WXaRRXWwSJ4Z-unEPmefryjFcYlwAxf3u0likfsJUcMi5kbnNjcnlwdC1jZXJ0LnNlY3VyZWRucy5ldQ",
udp: true,
},
{
// Yandex DNS
stampStr: "sdns://AQQAAAAAAAAAEDc3Ljg4LjguNzg6MTUzNTMg04TAccn3RmKvKszVe13MlxTUB7atNgHhrtwG1W1JYyciMi5kbnNjcnlwdC1jZXJ0LmJyb3dzZXIueWFuZGV4Lm5ldA",
udp: true,
},
}
for _, test := range stamps {
if test.udp {
checkDnsCryptServer(t, test.stampStr, "udp")
}
checkDnsCryptServer(t, test.stampStr, "")
checkDnsCryptServer(t, test.stampStr, "tcp")
}
}
func checkDnsCryptServer(t *testing.T, stampStr string, proto string) {
client := Client{Proto: proto, Timeout: 10 * time.Second}
client := Client{Proto: proto, Timeout: 10 * time.Second, AdjustPayloadSize: true}
serverInfo, rtt, err := client.Dial(stampStr)
if err != nil {
t.Fatalf("Could not establish connection with %s", stampStr)