Fix missing Close when error occurs and abused connection pool (#35658)

Fix #35649

* Use upstream `git-lfs-transfer`
* The Close should be called when error occurs (bug fix)
* The connection pool should be shared (bug fix)
* Add more tests to cover "LFS over SSH download"

modules/private/internal.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"os"
 	"strings"
+	"sync"
 	"time"
 
 	"code.gitea.io/gitea/modules/httplib"
@@ -33,6 +34,35 @@ func getClientIP() string {
 	return strings.Fields(sshConnEnv)[0]
 }
 
+func dialContextInternalAPI(ctx context.Context, network, address string) (conn net.Conn, err error) {
+	d := net.Dialer{Timeout: 10 * time.Second}
+	if setting.Protocol == setting.HTTPUnix {
+		conn, err = d.DialContext(ctx, "unix", setting.HTTPAddr)
+	} else {
+		conn, err = d.DialContext(ctx, network, address)
+	}
+	if err != nil {
+		return nil, err
+	}
+	if setting.LocalUseProxyProtocol {
+		if err = proxyprotocol.WriteLocalHeader(conn); err != nil {
+			_ = conn.Close()
+			return nil, err
+		}
+	}
+	return conn, nil
+}
+
+var internalAPITransport = sync.OnceValue(func() http.RoundTripper {
+	return &http.Transport{
+		DialContext: dialContextInternalAPI,
+		TLSClientConfig: &tls.Config{
+			InsecureSkipVerify: true,
+			ServerName:         setting.Domain,
+		},
+	}
+})
+
 func NewInternalRequest(ctx context.Context, url, method string) *httplib.Request {
 	if setting.InternalToken == "" {
 		log.Fatal(`The INTERNAL_TOKEN setting is missing from the configuration file: %q.
@@ -43,49 +73,11 @@ Ensure you are running in the correct environment or set the correct configurati
 		log.Fatal("Invalid internal request URL: %q", url)
 	}
 
-	req := httplib.NewRequest(url, method).
+	return httplib.NewRequest(url, method).
 		SetContext(ctx).
+		SetTransport(internalAPITransport()).
 		Header("X-Real-IP", getClientIP()).
-		Header("X-Gitea-Internal-Auth", "Bearer "+setting.InternalToken).
-		SetTLSClientConfig(&tls.Config{
-			InsecureSkipVerify: true,
-			ServerName:         setting.Domain,
-		})
-
-	if setting.Protocol == setting.HTTPUnix {
-		req.SetTransport(&http.Transport{
-			DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
-				var d net.Dialer
-				conn, err := d.DialContext(ctx, "unix", setting.HTTPAddr)
-				if err != nil {
-					return conn, err
-				}
-				if setting.LocalUseProxyProtocol {
-					if err = proxyprotocol.WriteLocalHeader(conn); err != nil {
-						_ = conn.Close()
-						return nil, err
-					}
-				}
-				return conn, err
-			},
-		})
-	} else if setting.LocalUseProxyProtocol {
-		req.SetTransport(&http.Transport{
-			DialContext: func(ctx context.Context, network, address string) (net.Conn, error) {
-				var d net.Dialer
-				conn, err := d.DialContext(ctx, network, address)
-				if err != nil {
-					return conn, err
-				}
-				if err = proxyprotocol.WriteLocalHeader(conn); err != nil {
-					_ = conn.Close()
-					return nil, err
-				}
-				return conn, err
-			},
-		})
-	}
-	return req
+		Header("X-Gitea-Internal-Auth", "Bearer "+setting.InternalToken)
 }
 
 func newInternalRequestAPI(ctx context.Context, url, method string, body ...any) *httplib.Request {
@@ -98,6 +90,6 @@ func newInternalRequestAPI(ctx context.Context, url, method string, body ...any)
 		log.Fatal("Too many arguments for newInternalRequestAPI")
 	}
 
-	req.SetTimeout(10*time.Second, 60*time.Second)
+	req.SetReadWriteTimeout(60 * time.Second)
 	return req
 }