sync from refraction-networking/utls upstream

.github/workflows/go.yml

@@ -0,0 +1,28 @@
+# This workflow will build a golang project
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-go
+
+name: Go
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Set up Go
+      uses: actions/setup-go@v3
+      with:
+        go-version: 1.19
+
+    - name: Build
+      run: go build -v ./...
+
+    - name: Test
+      run: go test -v ./...

README.md

@@ -1,14 +1,17 @@
 # ![uTLS](logo_small.png) uTLS
-[![Build Status](https://travis-ci.org/refraction-networking/utls.svg?branch=master)](https://travis-ci.org/refraction-networking/utls)
+[![Build Status](https://github.com/refraction-networking/utls/actions/workflows/go.yml/badge.svg?branch=master)](https://github.com/refraction-networking/utls/actions)
 [![godoc](https://img.shields.io/badge/godoc-reference-blue.svg)](https://godoc.org/github.com/refraction-networking/utls#UConn)
 ---
 uTLS is a fork of "crypto/tls", which provides ClientHello fingerprinting resistance, low-level access to handshake, fake session tickets and some other features. Handshake is still performed by "crypto/tls", this library merely changes ClientHello part of it and provides low-level access.  
-Golang 1.11+ is required.  
-If you have any questions, bug reports or contributions, you are welcome to publish those on GitHub. If you want to do so in private, you can contact one of developers personally via [email protected]
+Golang 1.19+ is required.  
+
+If you have any questions, bug reports or contributions, you are welcome to publish those on GitHub. If you want to do so in private, you can contact one of developers personally via [email protected].
 
 Documentation below may not keep up with all the changes and new features at all times,
 so you are encouraged to use [godoc](https://godoc.org/github.com/refraction-networking/utls#UConn).
 
+*Note: Information provided below in this README.md could be obsolete.*
+
 # Features
 ## Low-level access to handshake
 * Read/write access to all bits of client hello message.  
@@ -161,6 +164,72 @@ To reuse tickets, create a shared cache and set it on current and further config
 func (uconn *UConn) SetSessionCache(cache ClientSessionCache)
 ```
 
+## Custom TLS extensions
+If you want to add your own fake (placeholder, without added functionality) extension for mimicry purposes, you can embed `*tls.GenericExtension` into your own struct and override `Len()` and `Read()` methods. For example, [DelegatedCredentials](https://datatracker.ietf.org/doc/draft-ietf-tls-subcerts/) extension can be implemented as follows:
+
+```Golang
+const FakeDelegatedCredentials uint16 = 0x0022
+
+type FakeDelegatedCredentialsExtension struct {
+	*tls.GenericExtension
+	SignatureAlgorithms []tls.SignatureScheme
+}
+
+func (e *FakeDelegatedCredentialsExtension) Len() int {
+	return 6 + 2*len(e.SignatureAlgorithms)
+}
+
+func (e *FakeDelegatedCredentialsExtension) Read(b []byte) (n int, err error) {
+	if len(b) < e.Len() {
+		return 0, io.ErrShortBuffer
+	}
+	offset := 0
+	appendUint16 := func(val uint16) {
+		b[offset] = byte(val >> 8)
+		b[offset+1] = byte(val & 0xff)
+		offset += 2
+	}
+
+	// Extension type
+	appendUint16(fakeDelegatedCredentials)
+
+	algosLength := 2 * len(e.SignatureAlgorithms)
+
+	// Extension data length
+	appendUint16(uint16(algosLength) + 2)
+
+	// Algorithms list length
+	appendUint16(uint16(algosLength))
+
+	// Algorithms list
+	for _, a := range e.SignatureAlgorithms {
+		appendUint16(uint16(a))
+	}
+	return e.Len(), io.EOF
+}
+```
+
+Then it can be used just like normal extension:
+
+```Golang
+&tls.ClientHelloSpec{
+	//...
+	Extensions: []tls.TLSExtension{
+		//...
+		&FakeDelegatedCredentialsExtension{
+			SignatureAlgorithms: []tls.SignatureScheme{
+				tls.ECDSAWithP256AndSHA256,
+				tls.ECDSAWithP384AndSHA384,
+				tls.ECDSAWithP521AndSHA512,
+				tls.ECDSAWithSHA1,
+			},
+		},
+		//...
+	}
+	//...
+}
+```
+
 # Client Hello IDs
 See full list of `clientHelloID` values [here](https://godoc.org/github.com/refraction-networking/utls#ClientHelloID).  
 There are different behaviors you can get, depending  on your `clientHelloID`:

alert.go

@@ -15,61 +15,75 @@ const (
 )
 
 const (
-	alertCloseNotify            alert = 0
-	alertUnexpectedMessage      alert = 10
-	alertBadRecordMAC           alert = 20
-	alertDecryptionFailed       alert = 21
-	alertRecordOverflow         alert = 22
-	alertDecompressionFailure   alert = 30
-	alertHandshakeFailure       alert = 40
-	alertBadCertificate         alert = 42
-	alertUnsupportedCertificate alert = 43
-	alertCertificateRevoked     alert = 44
-	alertCertificateExpired     alert = 45
-	alertCertificateUnknown     alert = 46
-	alertIllegalParameter       alert = 47
-	alertUnknownCA              alert = 48
-	alertAccessDenied           alert = 49
-	alertDecodeError            alert = 50
-	alertDecryptError           alert = 51
-	alertProtocolVersion        alert = 70
-	alertInsufficientSecurity   alert = 71
-	alertInternalError          alert = 80
-	alertInappropriateFallback  alert = 86
-	alertUserCanceled           alert = 90
-	alertNoRenegotiation        alert = 100
-	alertMissingExtension       alert = 109
-	alertUnsupportedExtension   alert = 110
-	alertNoApplicationProtocol  alert = 120
+	alertCloseNotify                  alert = 0
+	alertUnexpectedMessage            alert = 10
+	alertBadRecordMAC                 alert = 20
+	alertDecryptionFailed             alert = 21
+	alertRecordOverflow               alert = 22
+	alertDecompressionFailure         alert = 30
+	alertHandshakeFailure             alert = 40
+	alertBadCertificate               alert = 42
+	alertUnsupportedCertificate       alert = 43
+	alertCertificateRevoked           alert = 44
+	alertCertificateExpired           alert = 45
+	alertCertificateUnknown           alert = 46
+	alertIllegalParameter             alert = 47
+	alertUnknownCA                    alert = 48
+	alertAccessDenied                 alert = 49
+	alertDecodeError                  alert = 50
+	alertDecryptError                 alert = 51
+	alertExportRestriction            alert = 60
+	alertProtocolVersion              alert = 70
+	alertInsufficientSecurity         alert = 71
+	alertInternalError                alert = 80
+	alertInappropriateFallback        alert = 86
+	alertUserCanceled                 alert = 90
+	alertNoRenegotiation              alert = 100
+	alertMissingExtension             alert = 109
+	alertUnsupportedExtension         alert = 110
+	alertCertificateUnobtainable      alert = 111
+	alertUnrecognizedName             alert = 112
+	alertBadCertificateStatusResponse alert = 113
+	alertBadCertificateHashValue      alert = 114
+	alertUnknownPSKIdentity           alert = 115
+	alertCertificateRequired          alert = 116
+	alertNoApplicationProtocol        alert = 120
 )
 
 var alertText = map[alert]string{
-	alertCloseNotify:            "close notify",
-	alertUnexpectedMessage:      "unexpected message",
-	alertBadRecordMAC:           "bad record MAC",
-	alertDecryptionFailed:       "decryption failed",
-	alertRecordOverflow:         "record overflow",
-	alertDecompressionFailure:   "decompression failure",
-	alertHandshakeFailure:       "handshake failure",
-	alertBadCertificate:         "bad certificate",
-	alertUnsupportedCertificate: "unsupported certificate",
-	alertCertificateRevoked:     "revoked certificate",
-	alertCertificateExpired:     "expired certificate",
-	alertCertificateUnknown:     "unknown certificate",
-	alertIllegalParameter:       "illegal parameter",
-	alertUnknownCA:              "unknown certificate authority",
-	alertAccessDenied:           "access denied",
-	alertDecodeError:            "error decoding message",
-	alertDecryptError:           "error decrypting message",
-	alertProtocolVersion:        "protocol version not supported",
-	alertInsufficientSecurity:   "insufficient security level",
-	alertInternalError:          "internal error",
-	alertInappropriateFallback:  "inappropriate fallback",
-	alertUserCanceled:           "user canceled",
-	alertNoRenegotiation:        "no renegotiation",
-	alertMissingExtension:       "missing extension",
-	alertUnsupportedExtension:   "unsupported extension",
-	alertNoApplicationProtocol:  "no application protocol",
+	alertCloseNotify:                  "close notify",
+	alertUnexpectedMessage:            "unexpected message",
+	alertBadRecordMAC:                 "bad record MAC",
+	alertDecryptionFailed:             "decryption failed",
+	alertRecordOverflow:               "record overflow",
+	alertDecompressionFailure:         "decompression failure",
+	alertHandshakeFailure:             "handshake failure",
+	alertBadCertificate:               "bad certificate",
+	alertUnsupportedCertificate:       "unsupported certificate",
+	alertCertificateRevoked:           "revoked certificate",
+	alertCertificateExpired:           "expired certificate",
+	alertCertificateUnknown:           "unknown certificate",
+	alertIllegalParameter:             "illegal parameter",
+	alertUnknownCA:                    "unknown certificate authority",
+	alertAccessDenied:                 "access denied",
+	alertDecodeError:                  "error decoding message",
+	alertDecryptError:                 "error decrypting message",
+	alertExportRestriction:            "export restriction",
+	alertProtocolVersion:              "protocol version not supported",
+	alertInsufficientSecurity:         "insufficient security level",
+	alertInternalError:                "internal error",
+	alertInappropriateFallback:        "inappropriate fallback",
+	alertUserCanceled:                 "user canceled",
+	alertNoRenegotiation:              "no renegotiation",
+	alertMissingExtension:             "missing extension",
+	alertUnsupportedExtension:         "unsupported extension",
+	alertCertificateUnobtainable:      "certificate unobtainable",
+	alertUnrecognizedName:             "unrecognized name",
+	alertBadCertificateStatusResponse: "bad certificate status response",
+	alertBadCertificateHashValue:      "bad certificate hash value",
+	alertUnknownPSKIdentity:           "unknown PSK identity",
+	alertCertificateRequired:          "certificate required",
+	alertNoApplicationProtocol:        "no application protocol",
 }
 
 func (e alert) String() string {