Add Steam client signature cab2baf994ded9c9

internal/client/state.go

@@ -238,7 +238,9 @@ func (raw *RawConfig) ProcessRawConfig(worldState common.WorldState) (local Loca
 		case "firefox":
 			browser = &Firefox{}
 		case "chrome":
-			fallthrough
+			browser = &Chrome{}
+		case "steam":
+			browser = &Steam{}
 		default:
 			browser = &Chrome{}
 		}

internal/client/steam.go

@@ -0,0 +1,91 @@
+// Fingerprint of Steam Client
+
+package client
+
+import (
+	"encoding/binary"
+	"encoding/hex"
+)
+
+type Steam struct{}
+
+func (c *Steam) composeExtensions(serverName string, keyShare []byte) []byte {
+
+	makeSupportedGroups := func() []byte {
+		suppGroupListLen := []byte{0x00, 0x08}
+		ret := make([]byte, 2+8)
+		copy(ret[0:2], suppGroupListLen)
+		copy(ret[2:4], makeGREASE())
+		copy(ret[4:], []byte{0x00, 0x1d, 0x00, 0x17, 0x00, 0x18})
+		return ret
+	}
+
+	makeKeyShare := func(hidden []byte) []byte {
+		ret := make([]byte, 43)
+		ret[0], ret[1] = 0x00, 0x29 // length 41
+		copy(ret[2:4], makeGREASE())
+		ret[4], ret[5] = 0x00, 0x01 // length 1
+		ret[6] = 0x00
+		ret[7], ret[8] = 0x00, 0x1d  // group x25519
+		ret[9], ret[10] = 0x00, 0x20 // length 32
+		copy(ret[11:43], hidden)
+		return ret
+	}
+
+	// extension length is always 403, and server name length is variable
+
+	var ext [17][]byte
+	ext[0] = addExtRec(makeGREASE(), nil)                           // First GREASE
+	ext[1] = addExtRec([]byte{0x00, 0x00}, generateSNI(serverName)) // server name indication
+	ext[2] = addExtRec([]byte{0x00, 0x17}, nil)                     // extended_master_secret
+	ext[3] = addExtRec([]byte{0xff, 0x01}, []byte{0x00})            // renegotiation_info
+	ext[4] = addExtRec([]byte{0x00, 0x0a}, makeSupportedGroups())   // supported groups
+	ext[5] = addExtRec([]byte{0x00, 0x0b}, []byte{0x01, 0x00})      // ec point formats
+	ext[6] = addExtRec([]byte{0x00, 0x23}, nil)                     // Session tickets
+	ALPN, _ := hex.DecodeString("000c02683208687474702f312e31")
+	ext[7] = addExtRec([]byte{0x00, 0x10}, ALPN)                                 // app layer proto negotiation
+	ext[8] = addExtRec([]byte{0x00, 0x05}, []byte{0x01, 0x00, 0x00, 0x00, 0x00}) // status request
+	sigAlgo, _ := hex.DecodeString("001004030804040105030805050108060601")
+	ext[9] = addExtRec([]byte{0x00, 0x0d}, sigAlgo)                 // Signature Algorithms
+	ext[10] = addExtRec([]byte{0x00, 0x12}, nil)                    // signed cert timestamp
+	ext[11] = addExtRec([]byte{0x00, 0x33}, makeKeyShare(keyShare)) // key share
+	ext[12] = addExtRec([]byte{0x00, 0x2d}, []byte{0x01, 0x01})     // psk key exchange modes
+	suppVersions, _ := hex.DecodeString("0a9A9A0304030303020301")   // 9A9A needs to be a GREASE
+	copy(suppVersions[1:3], makeGREASE())
+	ext[13] = addExtRec([]byte{0x00, 0x2b}, suppVersions)             // supported versions
+	ext[14] = addExtRec([]byte{0x00, 0x1b}, []byte{0x02, 0x00, 0x02}) // compress certificate
+	ext[15] = addExtRec(makeGREASE(), []byte{0x00})                   // Last GREASE
+	// len(ext[1]) + 170 + len(ext[16]) = 403
+	// len(ext[16]) = 233 - len(ext[1])
+	// 2+2+len(padding) = 233 - len(ext[1])
+	// len(padding) = 229 - len(ext[1])
+	ext[16] = addExtRec([]byte{0x00, 0x15}, make([]byte, 229-len(ext[1]))) // padding
+	var ret []byte
+	for _, e := range ext {
+		ret = append(ret, e...)
+	}
+	return ret
+}
+
+func (c *Steam) composeClientHello(hd clientHelloFields) (ch []byte) {
+	var clientHello [12][]byte
+	clientHello[0] = []byte{0x01}             // handshake type
+	clientHello[1] = []byte{0x00, 0x01, 0xfc} // length 508
+	clientHello[2] = []byte{0x03, 0x03}       // client version
+	clientHello[3] = hd.random                // random
+	clientHello[4] = []byte{0x20}             // session id length 32
+	clientHello[5] = hd.sessionId             // session id
+	clientHello[6] = []byte{0x00, 0x20}       // cipher suites length 32
+	cipherSuites, _ := hex.DecodeString("130313011302cca9cca8c02bc02fc02cc030c013c014009c009d002f0035")
+	clientHello[7] = append(makeGREASE(), cipherSuites...) // cipher suites
+	clientHello[8] = []byte{0x01}                          // compression methods length 1
+	clientHello[9] = []byte{0x00}                          // compression methods
+	clientHello[11] = c.composeExtensions(hd.serverName, hd.x25519KeyShare)
+	clientHello[10] = []byte{0x00, 0x00} // extensions length 403
+	binary.BigEndian.PutUint16(clientHello[10], uint16(len(clientHello[11])))
+	var ret []byte
+	for _, c := range clientHello {
+		ret = append(ret, c...)
+	}
+	return ret
+}