feat: expose HTTP2 header and protocol limits

transport/http2/server.go

@@ -35,6 +35,7 @@ type Server struct {
 	MaxConnections        int
 	MaxConcurrentRequests int
 	MaxConcurrentStreams  uint32
+	MaxHeaderBytes        int
 	MaxBodyBytes          int64
 	IdleTimeout           time.Duration
 	TLSHandshakeTimeout   time.Duration
@@ -55,6 +56,7 @@ type Server struct {
 	accepted       atomic.Uint64
 	rejectedConns  atomic.Uint64
 	rejectedReqs   atomic.Uint64
+	protocolErrors atomic.Uint64
 	activeConns    atomic.Int64
 	activeRequests atomic.Int64
 	wg             sync.WaitGroup
@@ -66,6 +68,7 @@ type Stats struct {
 	AcceptedConnections uint64 `json:"acceptedConnections"`
 	RejectedConnections uint64 `json:"rejectedConnections"`
 	RejectedRequests    uint64 `json:"rejectedRequests"`
+	ProtocolErrors      uint64 `json:"protocolErrors"`
 	ActiveConnections   int64  `json:"activeConnections"`
 	ActiveRequests      int64  `json:"activeRequests"`
 }
@@ -89,6 +92,7 @@ func (s *Server) Stats() Stats {
 		AcceptedConnections: s.accepted.Load(),
 		RejectedConnections: s.rejectedConns.Load(),
 		RejectedRequests:    s.rejectedReqs.Load(),
+		ProtocolErrors:      s.protocolErrors.Load(),
 		ActiveConnections:   s.activeConns.Load(),
 		ActiveRequests:      s.activeRequests.Load(),
 	}
@@ -226,8 +230,11 @@ func (s *Server) Serve(ctx context.Context, listener net.Listener) error {
 	protocolServer := &xhttp2.Server{
 		MaxConcurrentStreams: s.MaxConcurrentStreams,
 		IdleTimeout:          s.IdleTimeout,
+		CountError: func(string) {
+			s.protocolErrors.Add(1)
+		},
 	}
-	shutdownConfig := &http.Server{IdleTimeout: s.IdleTimeout}
+	shutdownConfig := &http.Server{IdleTimeout: s.IdleTimeout, MaxHeaderBytes: s.MaxHeaderBytes}
 	if err := xhttp2.ConfigureServer(shutdownConfig, protocolServer); err != nil {
 		cancel()
 		s.mu.Lock()

transport/http2/server_test.go

@@ -14,6 +14,7 @@ import (
 	"math/big"
 	"net"
 	"net/http"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"testing"
@@ -175,6 +176,46 @@ func TestServerRejectsBodyAboveLimitAndRecovers(t *testing.T) {
 	}
 }
 
+func TestServerRejectsHeadersAboveLimitAndRecovers(t *testing.T) {
+	server := New(http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
+		_, _ = io.WriteString(writer, "ok")
+	}))
+	server.MaxHeaderBytes = 1024
+	address, stop := startServer(t, server)
+	defer stop()
+	transport := &xhttp2.Transport{
+		AllowHTTP: true,
+		DialTLSContext: func(ctx context.Context, network, address string, _ *tls.Config) (net.Conn, error) {
+			return (&net.Dialer{}).DialContext(ctx, network, address)
+		},
+	}
+	client := &http.Client{Transport: transport, Timeout: 3 * time.Second}
+	defer transport.CloseIdleConnections()
+
+	request, err := http.NewRequest(http.MethodGet, "http://"+address+"/too-large", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	request.Header.Set("X-Large", strings.Repeat("x", 2048))
+	response, err := client.Do(request)
+	if err == nil {
+		response.Body.Close()
+		if response.StatusCode < http.StatusBadRequest {
+			t.Fatalf("oversized headers unexpectedly succeeded with status %d", response.StatusCode)
+		}
+	}
+
+	response, err = client.Get("http://" + address + "/recovered")
+	if err != nil {
+		t.Fatal(err)
+	}
+	body, readErr := io.ReadAll(response.Body)
+	response.Body.Close()
+	if readErr != nil || response.StatusCode != http.StatusOK || string(body) != "ok" {
+		t.Fatalf("header limit did not recover: status=%d body=%q err=%v", response.StatusCode, body, readErr)
+	}
+}
+
 func TestServerMultiplexes128Streams(t *testing.T) {
 	started := make(chan struct{}, 128)
 	release := make(chan struct{})
@@ -196,7 +237,8 @@ func TestServerMultiplexes128Streams(t *testing.T) {
 	address, stop := startServer(t, server)
 	defer stop()
 	transport := &xhttp2.Transport{
-		AllowHTTP: true,
+		AllowHTTP:                  true,
+		StrictMaxConcurrentStreams: true,
 		DialTLSContext: func(ctx context.Context, network, address string, _ *tls.Config) (net.Conn, error) {
 			return (&net.Dialer{}).DialContext(ctx, network, address)
 		},