fix(web): report unexpected HTTP serve failures (#6210)

* fix(web): report unexpected HTTP serve failures

* test(web): cover normal close and all HTTP servers

---------

Co-authored-by: n0ctal <293235942+n0ctal@users.noreply.github.com>

internal/sub/sub.go

@@ -371,9 +371,7 @@ func (s *Server) Start() (err error) {
 		IdleTimeout:       120 * time.Second,
 	}
 
-	go func() {
-		_ = s.httpServer.Serve(listener)
-	}()
+	go network.ServeHTTP(s.httpServer, listener, "Subscription server")
 
 	return nil
 }

internal/web/network/serve.go

@@ -0,0 +1,17 @@
+package network
+
+import (
+	"errors"
+	"net"
+	"net/http"
+
+	"github.com/mhsanaei/3x-ui/v3/internal/logger"
+)
+
+// ServeHTTP runs a panel HTTP server and records unexpected listener failures.
+// A normal Shutdown returns http.ErrServerClosed and is intentionally silent.
+func ServeHTTP(server *http.Server, listener net.Listener, name string) {
+	if err := server.Serve(listener); err != nil && !errors.Is(err, http.ErrServerClosed) {
+		logger.Error(name, " stopped unexpectedly: ", err)
+	}
+}

internal/web/network/serve_test.go

@@ -0,0 +1,111 @@
+package network
+
+import (
+	"errors"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"net"
+	"net/http"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/mhsanaei/3x-ui/v3/internal/logger"
+)
+
+type failingListener struct{ err error }
+
+func (l failingListener) Accept() (net.Conn, error) { return nil, l.err }
+func (failingListener) Close() error                { return nil }
+func (failingListener) Addr() net.Addr              { return testAddr("failing") }
+
+type testAddr string
+
+func (a testAddr) Network() string { return string(a) }
+func (a testAddr) String() string  { return string(a) }
+
+func TestServeHTTPLogsUnexpectedListenerFailure(t *testing.T) {
+	errInjected := errors.New("injected listener failure")
+	ServeHTTP(&http.Server{}, failingListener{err: errInjected}, "Test server")
+
+	for _, line := range logger.GetLogs(100, "error") {
+		if strings.Contains(line, errInjected.Error()) {
+			return
+		}
+	}
+	t.Fatal("unexpected listener failure was not recorded in the panel log")
+}
+
+func TestServeHTTPSuppressesNormalServerClose(t *testing.T) {
+	const marker = "normal-close-must-stay-silent"
+	ServeHTTP(&http.Server{}, failingListener{err: http.ErrServerClosed}, marker)
+
+	for _, line := range logger.GetLogs(100, "error") {
+		if strings.Contains(line, marker) {
+			t.Fatalf("normal http.ErrServerClosed was recorded as an error: %s", line)
+		}
+	}
+}
+
+func TestProductionHTTPServersUseServeHTTPWrapper(t *testing.T) {
+	_, currentFile, _, ok := runtime.Caller(0)
+	if !ok {
+		t.Fatal("locate test source")
+	}
+	repoRoot := filepath.Clean(filepath.Join(filepath.Dir(currentFile), "../../.."))
+	fset := token.NewFileSet()
+
+	err := filepath.WalkDir(repoRoot, func(path string, entry os.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+		if entry.IsDir() {
+			if entry.Name() == ".git" || entry.Name() == "vendor" || entry.Name() == "node_modules" {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+		if !strings.HasSuffix(path, ".go") || strings.HasSuffix(path, "_test.go") || path == currentFile || path == filepath.Join(filepath.Dir(currentFile), "serve.go") {
+			return nil
+		}
+
+		parsed, err := parser.ParseFile(fset, path, nil, parser.ImportsOnly)
+		if err != nil {
+			return err
+		}
+		usesHTTP := false
+		for _, imp := range parsed.Imports {
+			if imp.Path.Value == `"net/http"` {
+				usesHTTP = true
+				break
+			}
+		}
+		if !usesHTTP {
+			return nil
+		}
+
+		parsed, err = parser.ParseFile(fset, path, nil, 0)
+		if err != nil {
+			return err
+		}
+		ast.Inspect(parsed, func(node ast.Node) bool {
+			call, ok := node.(*ast.CallExpr)
+			if !ok {
+				return true
+			}
+			selector, ok := call.Fun.(*ast.SelectorExpr)
+			if ok && selector.Sel.Name == "Serve" {
+				position := fset.Position(call.Pos())
+				t.Errorf("direct Serve call at %s; production HTTP servers must use network.ServeHTTP", position)
+			}
+			return true
+		})
+		return nil
+	})
+	if err != nil {
+		t.Fatalf("scan production Go files: %v", err)
+	}
+}

internal/web/web.go

@@ -591,9 +591,7 @@ func (s *Server) start(restartXray bool, startTgBot bool) (err error) {
 		IdleTimeout:       120 * time.Second,
 	}
 
-	go func() {
-		_ = s.httpServer.Serve(listener)
-	}()
+	go network.ServeHTTP(s.httpServer, listener, "Web server")
 
 	// Create event bus before startTask so jobs can use it
 	s.bus = eventbus.New(eventbus.DefaultBufferSize)