R74: recv handler panics, cache TTL race fix

internal/cache/backends/memory_shard.go

@@ -33,13 +33,14 @@ func newCacheShard(maxSize, maxMemory int64) *cacheShard {
 func (s *cacheShard) get(key string) (interface{}, bool, bool) {
 	s.mu.RLock()
 	item, exists := s.items[key]
+	expired := exists && item.isExpired()
 	s.mu.RUnlock()
 
 	if !exists {
 		return nil, false, false
 	}
 
-	if item.isExpired() {
+	if expired {
 		return nil, true, true // exists but expired
 	}
 
@@ -47,16 +48,19 @@ func (s *cacheShard) get(key string) (interface{}, bool, bool) {
 	s.mu.Lock()
 	// Re-check item exists (could have been deleted)
 	item, exists = s.items[key]
-	if exists && !item.isExpired() {
-		item.accessedAt = time.Now()
-		item.accessCount++
-		if elem, ok := item.element.(*list.Element); ok && elem != nil {
-			s.lruList.MoveToFront(elem)
+	if exists {
+		expired = item.isExpired()
+		if !expired {
+			item.accessedAt = time.Now()
+			item.accessCount++
+			if elem, ok := item.element.(*list.Element); ok && elem != nil {
+				s.lruList.MoveToFront(elem)
+			}
 		}
 	}
 	s.mu.Unlock()
 
-	if !exists || item.isExpired() {
+	if !exists || expired {
 		return nil, false, false
 	}
 
@@ -139,30 +143,32 @@ func (s *cacheShard) deleteIfExpired(key string) bool {
 func (s *cacheShard) exists(key string) bool {
 	s.mu.RLock()
 	item, exists := s.items[key]
+	expired := exists && item.isExpired()
 	s.mu.RUnlock()
 
-	if !exists {
-		return false
-	}
-
-	return !item.isExpired()
+	return exists && !expired
 }
 
 // ttl returns the remaining TTL for a key
 func (s *cacheShard) ttl(key string) (time.Duration, bool) {
 	s.mu.RLock()
 	item, exists := s.items[key]
+	expired := exists && item.isExpired()
+	var expiresAt time.Time
+	if exists {
+		expiresAt = item.expiresAt
+	}
 	s.mu.RUnlock()
 
-	if !exists || item.isExpired() {
+	if !exists || expired {
 		return 0, false
 	}
 
-	if item.expiresAt.IsZero() {
+	if expiresAt.IsZero() {
 		return 0, true // No expiration
 	}
 
-	remaining := time.Until(item.expiresAt)
+	remaining := time.Until(expiresAt)
 	if remaining < 0 {
 		return 0, false
 	}

internal/cache/backends/race_regression_test.go

@@ -0,0 +1,50 @@
+package backends
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+)
+
+// TestCache_TTLReadUnderConcurrentExpire exercises get/exists/ttl fast
+// paths racing with an in-place Expire that mutates expiresAt. Before
+// the fix the fast paths read expiresAt outside the lock, so under -race
+// this reports a data race on memoryCacheItem.expiresAt.
+func TestCache_TTLReadUnderConcurrentExpire(t *testing.T) {
+	c := NewMemoryCacheBackend(10000, 1024*1024*64, 0)
+	defer c.Close()
+
+	ctx := context.Background()
+	if err := c.Set(ctx, "k", "v", time.Hour); err != nil {
+		t.Fatalf("set: %v", err)
+	}
+
+	stop := make(chan struct{})
+	var wg sync.WaitGroup
+	for i := 0; i < 4; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for {
+				select {
+				case <-stop:
+					return
+				default:
+				}
+				_, _ = c.Get(ctx, "k")
+				_, _ = c.Exists(ctx, "k")
+				_, _ = c.TTL(ctx, "k")
+			}
+		}()
+	}
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		for i := 0; i < 2000; i++ {
+			_ = c.Expire(ctx, "k", time.Hour)
+		}
+		close(stop)
+	}()
+	wg.Wait()
+}

middleware.go

@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"fmt"
 	"net/http"
+	"runtime/debug"
 	"strings"
 	"sync/atomic"
 	"time"
@@ -172,6 +173,19 @@ func (t *TraefikOidc) applyBypassUserHeaders(req *http.Request, reason string) (
 //   - rw: The HTTP response writer.
 //   - req: The incoming HTTP request.
 func (t *TraefikOidc) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
+	// Recover from any panic in the handler chain (session decode, token
+	// validation, header injection, authorize-url build) so a bug answers a
+	// single clean 500 (and logs a stack) instead of escaping to net/http,
+	// which closes/truncates the connection. WriteHeader is idempotent, so
+	// this is safe even if a handler already wrote headers; Write appends.
+	defer func() {
+		if r := recover(); r != nil {
+			t.logger.Errorf("OIDC handler panic recovered: %v\n%s", r, debug.Stack())
+			rw.WriteHeader(http.StatusInternalServerError)
+			_, _ = rw.Write([]byte("Internal Server Error"))
+		}
+	}()
+
 	// Log request entry for debugging routing issues
 	t.logger.Debugf("Incoming request: %s %s", req.Method, req.URL.Path)
 

review_r74_test.go

@@ -0,0 +1,29 @@
+package traefikoidc
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+// TestServeHTTP_RecoversHandlerPanic regresses the request-handler path
+// having no panic recovery: a panic in the chain (here, the downstream
+// backend) now answers a clean 500 + body instead of escaping to
+// net/http (which closes/truncates the connection).
+func TestServeHTTP_RecoversHandlerPanic(t *testing.T) {
+	oidc := &TraefikOidc{
+		next: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			panic("boom")
+		}),
+		logger:       NewLogger("error"),
+		excludedURLs: map[string]struct{}{"/health": {}},
+	}
+
+	rw := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/health", nil)
+	oidc.ServeHTTP(rw, req) // must not panic
+
+	if rw.Code != http.StatusInternalServerError {
+		t.Fatalf("expected 500 from recovered panic, got %d", rw.Code)
+	}
+}