feat(auth): add custom HTTP client with utls for Claude API authentication

Introduce a custom HTTP client utilizing utls with Firefox TLS fingerprinting to bypass Cloudflare fingerprinting on Anthropic domains. Includes support for proxy configuration and enhanced connection management for HTTP/2.

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/joho/godotenv v1.5.1
 	github.com/klauspost/compress v1.17.4
 	github.com/minio/minio-go/v7 v7.0.66
+	github.com/refraction-networking/utls v1.8.2
 	github.com/sirupsen/logrus v1.9.3
 	github.com/skratchdot/open-golang v0.0.0-20200116055534-eef842397966
 	github.com/tidwall/gjson v1.18.0

go.sum

@@ -118,6 +118,8 @@ github.com/pjbgf/sha1cd v0.5.0 h1:a+UkboSi1znleCDUNT3M5YxjOnN1fz2FhN48FlwCxs0=
 github.com/pjbgf/sha1cd v0.5.0/go.mod h1:lhpGlyHLpQZoxMv8HcgXvZEhcGs0PG/vsZnEJ7H0iCM=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/refraction-networking/utls v1.8.2 h1:j4Q1gJj0xngdeH+Ox/qND11aEfhpgoEvV+S9iJ2IdQo=
+github.com/refraction-networking/utls v1.8.2/go.mod h1:jkSOEkLqn+S/jtpEHPOsVv/4V4EVnelwbMQl4vCWXAM=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
 github.com/rs/xid v1.5.0 h1:mKX4bl4iPYJtEIxp6CYiUuLQ/8DYMoz0PUdtGgMFRVc=

internal/auth/claude/anthropic_auth.go

@@ -14,7 +14,6 @@ import (
 	"time"
 
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
-	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -51,7 +50,8 @@ type ClaudeAuth struct {
 }
 
 // NewClaudeAuth creates a new Anthropic authentication service.
-// It initializes the HTTP client with proxy settings from the configuration.
+// It initializes the HTTP client with a custom TLS transport that uses Firefox
+// fingerprint to bypass Cloudflare's TLS fingerprinting on Anthropic domains.
 //
 // Parameters:
 //   - cfg: The application configuration containing proxy settings
@@ -59,8 +59,10 @@ type ClaudeAuth struct {
 // 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
 	return &ClaudeAuth{
-		httpClient: util.SetProxy(&cfg.SDKConfig, &http.Client{}),
+		httpClient: NewAnthropicHttpClient(&cfg.SDKConfig),
 	}
 }
 

internal/auth/claude/utls_transport.go

@@ -0,0 +1,165 @@
+// Package claude provides authentication functionality for Anthropic's Claude API.
+// This file implements a custom HTTP transport using utls to bypass TLS fingerprinting.
+package claude
+
+import (
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+
+	tls "github.com/refraction-networking/utls"
+	"github.com/router-for-me/CLIProxyAPI/v6/sdk/config"
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/net/http2"
+	"golang.org/x/net/proxy"
+)
+
+// utlsRoundTripper implements http.RoundTripper using utls with Firefox fingerprint
+// to bypass Cloudflare's TLS fingerprinting on Anthropic domains.
+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
+}
+
+// newUtlsRoundTripper creates a new utls-based round tripper with optional proxy support
+func newUtlsRoundTripper(cfg *config.SDKConfig) *utlsRoundTripper {
+	var dialer proxy.Dialer = proxy.Direct
+	if cfg != nil && cfg.ProxyURL != "" {
+		proxyURL, err := url.Parse(cfg.ProxyURL)
+		if err != nil {
+			log.Errorf("failed to parse proxy URL %q: %v", cfg.ProxyURL, err)
+		} else {
+			pDialer, err := proxy.FromURL(proxyURL, proxy.Direct)
+			if err != nil {
+				log.Errorf("failed to create proxy dialer for %q: %v", cfg.ProxyURL, err)
+			} else {
+				dialer = pDialer
+			}
+		}
+	}
+
+	return &utlsRoundTripper{
+		connections: make(map[string]*http2.ClientConn),
+		pending:     make(map[string]*sync.Cond),
+		dialer:      dialer,
+	}
+}
+
+// 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()
+
+	if err != nil {
+		return nil, err
+	}
+
+	// Store the new connection
+	t.connections[host] = h2Conn
+	return h2Conn, nil
+}
+
+// createConnection creates a new HTTP/2 connection with Firefox TLS fingerprint
+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.HelloFirefox_Auto)
+
+	if err := tlsConn.Handshake(); err != nil {
+		conn.Close()
+		return nil, err
+	}
+
+	tr := &http2.Transport{}
+	h2Conn, err := tr.NewClientConn(tlsConn)
+	if err != nil {
+		tlsConn.Close()
+		return nil, err
+	}
+
+	return h2Conn, nil
+}
+
+// RoundTrip implements http.RoundTripper
+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
+}
+
+// NewAnthropicHttpClient creates an HTTP client that bypasses TLS fingerprinting
+// for Anthropic domains by using utls with Firefox fingerprint.
+// It accepts optional SDK configuration for proxy settings.
+func NewAnthropicHttpClient(cfg *config.SDKConfig) *http.Client {
+	return &http.Client{
+		Transport: newUtlsRoundTripper(cfg),
+	}
+}

sdk/auth/claude.go

@@ -176,13 +176,16 @@ waitForCallback:
 	}
 
 	if result.State != state {
+		log.Errorf("State mismatch: expected %s, got %s", state, result.State)
 		return nil, claude.NewAuthenticationError(claude.ErrInvalidState, fmt.Errorf("state mismatch"))
 	}
 
 	log.Debug("Claude authorization code received; exchanging for tokens")
+	log.Debugf("Code: %s, State: %s", result.Code[:min(20, len(result.Code))], state)
 
 	authBundle, err := authSvc.ExchangeCodeForTokens(ctx, result.Code, state, pkceCodes)
 	if err != nil {
+		log.Errorf("Token exchange failed: %v", err)
 		return nil, claude.NewAuthenticationError(claude.ErrCodeExchangeFailed, err)
 	}