Preserve default transport settings for proxy clients

sdk/proxyutil/proxy.go

@@ -68,14 +68,18 @@ func Parse(raw string) (Setting, error) {
 	}
 }
 
+func cloneDefaultTransport() *http.Transport {
+	if transport, ok := http.DefaultTransport.(*http.Transport); ok && transport != nil {
+		return transport.Clone()
+	}
+	return &http.Transport{}
+}
+
 // NewDirectTransport returns a transport that bypasses environment proxies.
 func NewDirectTransport() *http.Transport {
-	if transport, ok := http.DefaultTransport.(*http.Transport); ok && transport != nil {
+	clone := cloneDefaultTransport()
-		clone := transport.Clone()
+	clone.Proxy = nil
-		clone.Proxy = nil
+	return clone
-		return clone
-	}
-	return &http.Transport{Proxy: nil}
 }
 
 // BuildHTTPTransport constructs an HTTP transport for the provided proxy setting.
@@ -102,14 +106,16 @@ func BuildHTTPTransport(raw string) (*http.Transport, Mode, error) {
 			if errSOCKS5 != nil {
 				return nil, setting.Mode, fmt.Errorf("create SOCKS5 dialer failed: %w", errSOCKS5)
 			}
-			return &http.Transport{
+			transport := cloneDefaultTransport()
-				Proxy: nil,
+			transport.Proxy = nil
-				DialContext: func(_ context.Context, network, addr string) (net.Conn, error) {
+			transport.DialContext = func(_ context.Context, network, addr string) (net.Conn, error) {
-					return dialer.Dial(network, addr)
+				return dialer.Dial(network, addr)
-				},
+			}
-			}, setting.Mode, nil
+			return transport, setting.Mode, nil
 		}
-		return &http.Transport{Proxy: http.ProxyURL(setting.URL)}, setting.Mode, nil
+		transport := cloneDefaultTransport()
+		transport.Proxy = http.ProxyURL(setting.URL)
+		return transport, setting.Mode, nil
 	default:
 		return nil, setting.Mode, nil
 	}

sdk/proxyutil/proxy_test.go

@@ -5,6 +5,16 @@ import (
 	"testing"
 )
 
+func mustDefaultTransport(t *testing.T) *http.Transport {
+	t.Helper()
+
+	transport, ok := http.DefaultTransport.(*http.Transport)
+	if !ok || transport == nil {
+		t.Fatal("http.DefaultTransport is not an *http.Transport")
+	}
+	return transport
+}
+
 func TestParse(t *testing.T) {
 	t.Parallel()
 
@@ -86,4 +96,44 @@ func TestBuildHTTPTransportHTTPProxy(t *testing.T) {
 	if proxyURL == nil || proxyURL.String() != "http://proxy.example.com:8080" {
 		t.Fatalf("proxy URL = %v, want http://proxy.example.com:8080", proxyURL)
 	}
+
+	defaultTransport := mustDefaultTransport(t)
+	if transport.ForceAttemptHTTP2 != defaultTransport.ForceAttemptHTTP2 {
+		t.Fatalf("ForceAttemptHTTP2 = %v, want %v", transport.ForceAttemptHTTP2, defaultTransport.ForceAttemptHTTP2)
+	}
+	if transport.IdleConnTimeout != defaultTransport.IdleConnTimeout {
+		t.Fatalf("IdleConnTimeout = %v, want %v", transport.IdleConnTimeout, defaultTransport.IdleConnTimeout)
+	}
+	if transport.TLSHandshakeTimeout != defaultTransport.TLSHandshakeTimeout {
+		t.Fatalf("TLSHandshakeTimeout = %v, want %v", transport.TLSHandshakeTimeout, defaultTransport.TLSHandshakeTimeout)
+	}
+}
+
+func TestBuildHTTPTransportSOCKS5ProxyInheritsDefaultTransportSettings(t *testing.T) {
+	t.Parallel()
+
+	transport, mode, errBuild := BuildHTTPTransport("socks5://proxy.example.com:1080")
+	if errBuild != nil {
+		t.Fatalf("BuildHTTPTransport returned error: %v", errBuild)
+	}
+	if mode != ModeProxy {
+		t.Fatalf("mode = %d, want %d", mode, ModeProxy)
+	}
+	if transport == nil {
+		t.Fatal("expected transport, got nil")
+	}
+	if transport.Proxy != nil {
+		t.Fatal("expected SOCKS5 transport to bypass http proxy function")
+	}
+
+	defaultTransport := mustDefaultTransport(t)
+	if transport.ForceAttemptHTTP2 != defaultTransport.ForceAttemptHTTP2 {
+		t.Fatalf("ForceAttemptHTTP2 = %v, want %v", transport.ForceAttemptHTTP2, defaultTransport.ForceAttemptHTTP2)
+	}
+	if transport.IdleConnTimeout != defaultTransport.IdleConnTimeout {
+		t.Fatalf("IdleConnTimeout = %v, want %v", transport.IdleConnTimeout, defaultTransport.IdleConnTimeout)
+	}
+	if transport.TLSHandshakeTimeout != defaultTransport.TLSHandshakeTimeout {
+		t.Fatalf("TLSHandshakeTimeout = %v, want %v", transport.TLSHandshakeTimeout, defaultTransport.TLSHandshakeTimeout)
+	}
 }