fix: unify Anthropic TLS fingerprint to Bun BoringSSL

internal/auth/claude/anthropic_auth.go

@@ -50,19 +50,26 @@ type ClaudeAuth struct {
 }
 
 // NewClaudeAuth creates a new Anthropic authentication service.
-// It initializes the HTTP client with a custom TLS transport that uses Firefox
-// fingerprint to bypass Cloudflare's TLS fingerprinting on Anthropic domains.
+// It initializes the HTTP client with a custom TLS transport that uses Bun BoringSSL
+// fingerprint to match real Claude Code CLI behavior.
+//
+// An optional proxyURL may be provided to override the proxy in cfg.SDKConfig.
+// This allows callers to pass a pre-resolved proxy URL (e.g. from ResolveProxyURL)
+// so that both request and refresh paths share the same proxy priority logic.
 //
 // Parameters:
 //   - cfg: The application configuration containing proxy settings
+//   - proxyURL: Optional pre-resolved proxy URL that overrides cfg.SDKConfig.ProxyURL
 //
 // Returns:
 //   - *ClaudeAuth: A new Claude authentication service instance
-func NewClaudeAuth(cfg *config.Config) *ClaudeAuth {
-	// Use custom HTTP client with Firefox TLS fingerprint to bypass
-	// Cloudflare's bot detection on Anthropic domains
+func NewClaudeAuth(cfg *config.Config, proxyURL ...string) *ClaudeAuth {
+	pURL := cfg.SDKConfig.ProxyURL
+	if len(proxyURL) > 0 && proxyURL[0] != "" {
+		pURL = proxyURL[0]
+	}
 	return &ClaudeAuth{
-		httpClient: NewAnthropicHttpClient(&cfg.SDKConfig),
+		httpClient: NewAnthropicHttpClient(pURL),
 	}
 }
 

internal/auth/claude/bun_tls_spec.go

@@ -0,0 +1,131 @@
+// Bun v1.3.x (BoringSSL) TLS ClientHello Spec for utls
+// Captured from real Claude Code 2.1.71 / Bun v1.3.8 via tls.peet.ws
+//
+// JA3 Hash: 50027c67d7d68e24c00d233bca146d88
+// JA3: 771,4865-4866-4867-49195-49199-49196-49200-52393-52392-49161-49171-49162-49172-156-157-47-53,0-65037-23-65281-10-11-35-16-5-13-18-51-45-43-21,29-23-24,0
+// JA4: t13d1715h1_5b57614c22b0_7baf387fc6ff
+//
+// Key differences from Chrome:
+//   - No GREASE (Chrome injects random GREASE values)
+//   - ALPN: http/1.1 only (Chrome: h2 + http/1.1)
+//   - Fewer extensions (no compress_certificate, no delegated_credentials)
+//   - ECH extension 65037 present (BoringSSL-specific)
+
+package claude
+
+import (
+	tls "github.com/refraction-networking/utls"
+)
+
+// BunBoringSSLSpec returns a utls ClientHelloSpec that exactly matches
+// Bun v1.3.x's BoringSSL TLS fingerprint, as used by Claude Code CLI.
+//
+// This ensures TLS fingerprint consistency between API requests and
+// token refresh, matching what Anthropic sees from real Claude Code users.
+func BunBoringSSLSpec() *tls.ClientHelloSpec {
+	return &tls.ClientHelloSpec{
+		TLSVersMin: tls.VersionTLS12,
+		TLSVersMax: tls.VersionTLS13,
+		CipherSuites: []uint16{
+			// TLS 1.3 suites
+			tls.TLS_AES_128_GCM_SHA256,       // 0x1301
+			tls.TLS_AES_256_GCM_SHA384,       // 0x1302
+			tls.TLS_CHACHA20_POLY1305_SHA256,  // 0x1303
+			// TLS 1.2 ECDHE suites
+			tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,       // 0xC02B
+			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,         // 0xC02F
+			tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,       // 0xC02C
+			tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,         // 0xC030
+			tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256, // 0xCCA9
+			tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,   // 0xCCA8
+			tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,          // 0xC009
+			tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,            // 0xC013
+			tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,          // 0xC00A
+			tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,            // 0xC014
+			// TLS 1.2 RSA suites
+			tls.TLS_RSA_WITH_AES_128_GCM_SHA256, // 0x009C
+			tls.TLS_RSA_WITH_AES_256_GCM_SHA384, // 0x009D
+			tls.TLS_RSA_WITH_AES_128_CBC_SHA,    // 0x002F
+			tls.TLS_RSA_WITH_AES_256_CBC_SHA,    // 0x0035
+		},
+		Extensions: []tls.TLSExtension{
+			// 0 - Server Name Indication
+			&tls.SNIExtension{},
+
+			// 65037 - Encrypted Client Hello (BoringSSL-specific)
+			&tls.GenericExtension{Id: 65037},
+
+			// 23 - Extended Master Secret
+			&tls.ExtendedMasterSecretExtension{},
+
+			// 65281 - Renegotiation Info
+			&tls.RenegotiationInfoExtension{Renegotiation: tls.RenegotiateOnceAsClient},
+
+			// 10 - Supported Groups
+			&tls.SupportedCurvesExtension{
+				Curves: []tls.CurveID{
+					tls.X25519,    // 29
+					tls.CurveP256, // 23
+					tls.CurveP384, // 24
+				},
+			},
+
+			// 11 - EC Point Formats
+			&tls.SupportedPointsExtension{
+				SupportedPoints: []byte{0x00}, // uncompressed
+			},
+
+			// 35 - Session Ticket
+			&tls.SessionTicketExtension{},
+
+			// 16 - ALPN (http/1.1 ONLY — Bun does not negotiate h2)
+			&tls.ALPNExtension{
+				AlpnProtocols: []string{"http/1.1"},
+			},
+
+			// 5 - Status Request (OCSP)
+			&tls.StatusRequestExtension{},
+
+			// 13 - Signature Algorithms
+			&tls.SignatureAlgorithmsExtension{
+				SupportedSignatureAlgorithms: []tls.SignatureScheme{
+					tls.ECDSAWithP256AndSHA256, // 0x0403
+					tls.PSSWithSHA256,          // 0x0804
+					tls.PKCS1WithSHA256,        // 0x0401
+					tls.ECDSAWithP384AndSHA384, // 0x0503
+					tls.PSSWithSHA384,          // 0x0805
+					tls.PKCS1WithSHA384,        // 0x0501
+					tls.PSSWithSHA512,          // 0x0806
+					tls.PKCS1WithSHA512,        // 0x0601
+					tls.PKCS1WithSHA1,          // 0x0201
+				},
+			},
+
+			// 18 - Signed Certificate Timestamp (SCT)
+			&tls.SCTExtension{},
+
+			// 51 - Key Share (X25519)
+			&tls.KeyShareExtension{
+				KeyShares: []tls.KeyShare{
+					{Group: tls.X25519},
+				},
+			},
+
+			// 45 - PSK Key Exchange Modes
+			&tls.PSKKeyExchangeModesExtension{
+				Modes: []uint8{tls.PskModeDHE}, // psk_dhe_ke (1)
+			},
+
+			// 43 - Supported Versions
+			&tls.SupportedVersionsExtension{
+				Versions: []uint16{
+					tls.VersionTLS13, // 0x0304
+					tls.VersionTLS12, // 0x0303
+				},
+			},
+
+			// 21 - Padding
+			&tls.UtlsPaddingExtension{GetPaddingLen: tls.BoringPaddingStyle},
+		},
+	}
+}

internal/auth/claude/utls_transport.go

@@ -1,162 +1,98 @@
 // Package claude provides authentication functionality for Anthropic's Claude API.
-// This file implements a custom HTTP transport using utls to bypass TLS fingerprinting.
+// This file implements a custom HTTP transport using utls to mimic Bun's BoringSSL
+// TLS fingerprint, matching the real Claude Code CLI.
 package claude
 
 import (
+	"context"
+	"fmt"
+	"net"
 	"net/http"
-	"strings"
-	"sync"
 
 	tls "github.com/refraction-networking/utls"
-	"github.com/router-for-me/CLIProxyAPI/v6/sdk/config"
 	"github.com/router-for-me/CLIProxyAPI/v6/sdk/proxyutil"
 	log "github.com/sirupsen/logrus"
-	"golang.org/x/net/http2"
 	"golang.org/x/net/proxy"
 )
 
-// utlsRoundTripper implements http.RoundTripper using utls with Chrome fingerprint
-// to bypass Cloudflare's TLS fingerprinting on Anthropic domains.
+// utlsRoundTripper implements http.RoundTripper using utls with Bun BoringSSL
+// fingerprint to match the real Claude Code CLI's TLS characteristics.
+//
+// It uses HTTP/1.1 (Bun's ALPN only offers http/1.1) and delegates connection
+// pooling to the standard http.Transport.
 type utlsRoundTripper struct {
-	// mu protects the connections map and pending map
-	mu sync.Mutex
-	// connections caches HTTP/2 client connections per host
-	connections map[string]*http2.ClientConn
-	// pending tracks hosts that are currently being connected to (prevents race condition)
-	pending map[string]*sync.Cond
-	// dialer is used to create network connections, supporting proxies
-	dialer proxy.Dialer
+	transport *http.Transport
+	dialer    proxy.Dialer
 }
 
-// newUtlsRoundTripper creates a new utls-based round tripper with optional proxy support
-func newUtlsRoundTripper(cfg *config.SDKConfig) *utlsRoundTripper {
+// newUtlsRoundTripper creates a new utls-based round tripper with optional proxy support.
+// The proxyURL parameter is the pre-resolved proxy URL string; an empty string means
+// no proxy (direct connection).
+func newUtlsRoundTripper(proxyURL string) *utlsRoundTripper {
 	var dialer proxy.Dialer = proxy.Direct
-	if cfg != nil {
-		proxyDialer, mode, errBuild := proxyutil.BuildDialer(cfg.ProxyURL)
+	if proxyURL != "" {
+		proxyDialer, mode, errBuild := proxyutil.BuildDialer(proxyURL)
 		if errBuild != nil {
-			log.Errorf("failed to configure proxy dialer for %q: %v", cfg.ProxyURL, errBuild)
+			log.Errorf("failed to configure proxy dialer for %q: %v", proxyURL, errBuild)
 		} else if mode != proxyutil.ModeInherit && proxyDialer != nil {
 			dialer = proxyDialer
 		}
 	}
 
-	return &utlsRoundTripper{
-		connections: make(map[string]*http2.ClientConn),
-		pending:     make(map[string]*sync.Cond),
-		dialer:      dialer,
+	rt := &utlsRoundTripper{dialer: dialer}
+	rt.transport = &http.Transport{
+		// Inject our custom TLS dial function so every connection uses
+		// the Bun BoringSSL fingerprint via utls.
+		DialTLSContext: rt.dialTLS,
+		// Force HTTP/1.1 — do not attempt h2 upgrade.
+		ForceAttemptHTTP2: false,
 	}
+	return rt
 }
 
-// getOrCreateConnection gets an existing connection or creates a new one.
-// It uses a per-host locking mechanism to prevent multiple goroutines from
-// creating connections to the same host simultaneously.
-func (t *utlsRoundTripper) getOrCreateConnection(host, addr string) (*http2.ClientConn, error) {
-	t.mu.Lock()
-
-	// Check if connection exists and is usable
-	if h2Conn, ok := t.connections[host]; ok && h2Conn.CanTakeNewRequest() {
-		t.mu.Unlock()
-		return h2Conn, nil
-	}
-
-	// Check if another goroutine is already creating a connection
-	if cond, ok := t.pending[host]; ok {
-		// Wait for the other goroutine to finish
-		cond.Wait()
-		// Check if connection is now available
-		if h2Conn, ok := t.connections[host]; ok && h2Conn.CanTakeNewRequest() {
-			t.mu.Unlock()
-			return h2Conn, nil
-		}
-		// Connection still not available, we'll create one
-	}
-
-	// Mark this host as pending
-	cond := sync.NewCond(&t.mu)
-	t.pending[host] = cond
-	t.mu.Unlock()
-
-	// Create connection outside the lock
-	h2Conn, err := t.createConnection(host, addr)
-
-	t.mu.Lock()
-	defer t.mu.Unlock()
-
-	// Remove pending marker and wake up waiting goroutines
-	delete(t.pending, host)
-	cond.Broadcast()
-
+// dialTLS establishes a TLS connection using utls with the Bun BoringSSL spec.
+// This is called by http.Transport for every new TLS connection.
+func (t *utlsRoundTripper) dialTLS(ctx context.Context, network, addr string) (net.Conn, error) {
+	host, _, err := net.SplitHostPort(addr)
 	if err != nil {
-		return nil, err
+		// addr might not have a port; use as-is for ServerName
+		host = addr
 	}
 
-	// Store the new connection
-	t.connections[host] = h2Conn
-	return h2Conn, nil
-}
-
-// createConnection creates a new HTTP/2 connection with Chrome TLS fingerprint.
-// Chrome's TLS fingerprint is closer to Node.js/OpenSSL (which real Claude Code uses)
-// than Firefox, reducing the mismatch between TLS layer and HTTP headers.
-func (t *utlsRoundTripper) createConnection(host, addr string) (*http2.ClientConn, error) {
 	conn, err := t.dialer.Dial("tcp", addr)
 	if err != nil {
 		return nil, err
 	}
 
 	tlsConfig := &tls.Config{ServerName: host}
-	tlsConn := tls.UClient(conn, tlsConfig, tls.HelloChrome_Auto)
-
-	if err := tlsConn.Handshake(); err != nil {
+	tlsConn := tls.UClient(conn, tlsConfig, tls.HelloCustom)
+	if err := tlsConn.ApplyPreset(BunBoringSSLSpec()); err != nil {
 		conn.Close()
-		return nil, err
+		return nil, fmt.Errorf("apply Bun TLS spec: %w", err)
 	}
 
-	tr := &http2.Transport{}
-	h2Conn, err := tr.NewClientConn(tlsConn)
-	if err != nil {
-		tlsConn.Close()
+	if err := tlsConn.Handshake(); err != nil {
+		conn.Close()
 		return nil, err
 	}
 
-	return h2Conn, nil
+	return tlsConn, nil
 }
 
-// RoundTrip implements http.RoundTripper
+// RoundTrip implements http.RoundTripper by delegating to the underlying
+// http.Transport which uses our custom TLS dial function.
 func (t *utlsRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
-	host := req.URL.Host
-	addr := host
-	if !strings.Contains(addr, ":") {
-		addr += ":443"
-	}
-
-	// Get hostname without port for TLS ServerName
-	hostname := req.URL.Hostname()
-
-	h2Conn, err := t.getOrCreateConnection(hostname, addr)
-	if err != nil {
-		return nil, err
-	}
-
-	resp, err := h2Conn.RoundTrip(req)
-	if err != nil {
-		// Connection failed, remove it from cache
-		t.mu.Lock()
-		if cached, ok := t.connections[hostname]; ok && cached == h2Conn {
-			delete(t.connections, hostname)
-		}
-		t.mu.Unlock()
-		return nil, err
-	}
-
-	return resp, nil
+	return t.transport.RoundTrip(req)
 }
 
-// NewAnthropicHttpClient creates an HTTP client that bypasses TLS fingerprinting
-// for Anthropic domains by using utls with Chrome fingerprint.
-// It accepts optional SDK configuration for proxy settings.
-func NewAnthropicHttpClient(cfg *config.SDKConfig) *http.Client {
+// NewAnthropicHttpClient creates an HTTP client that uses Bun BoringSSL TLS
+// fingerprint for all connections, matching real Claude Code CLI behavior.
+//
+// The proxyURL parameter is the pre-resolved proxy URL (e.g. from ResolveProxyURL).
+// Pass an empty string for direct connections.
+func NewAnthropicHttpClient(proxyURL string) *http.Client {
 	return &http.Client{
-		Transport: newUtlsRoundTripper(cfg),
+		Transport: newUtlsRoundTripper(proxyURL),
 	}
 }
+