fix: log cmpp packet decode failures

gateway/internal/inbound/server.go

@@ -25,6 +25,7 @@ type Server struct {
 	Addr                 string
 	APIBaseURL           string
 	HTTPClient           *http.Client
+	LogWriter            io.Writer
 	PendingFlushInterval time.Duration
 	PresenceStore        PresenceStore
 	RecoveryStore        RecoveryStore
@@ -116,7 +117,7 @@ func (s Server) ListenAndServe() error {
 	s.logRecoveryCandidates(log.Default())
 	go s.recoverPendingCandidates(log.Default())
 	go s.runPendingFlusher(log.Default())
-	return cmpp.ListenAndServe(addr, cmpp.V30, 30*time.Second, 3, nil,
+	return cmpp.ListenAndServe(addr, cmpp.V30, 30*time.Second, 3, s.LogWriter,
 		cmpp.HandlerFunc(s.handleLogin),
 		cmpp.HandlerFunc(s.handleSubmit),
 	)
@@ -158,7 +159,7 @@ func (s Server) handleLogin(response *cmpp.Response, packet *cmpp.Packet, logger
 	go s.flushPending(defaultString(auth.Account, account), logger)
 	logger.Printf(
 		"cmpp inbound event=login_accepted protocol=%s requested_version=0x%02x response_version=0x30 account=%s remote=%s",
-		cmppVersionName(req.Version), req.Version, account, packet.Conn.Conn.RemoteAddr(),
+		cmppVersionName(req.Version), uint8(req.Version), account, packet.Conn.Conn.RemoteAddr(),
 	)
 	return false, nil
 }

gateway/internal/inbound/server_test.go

@@ -3,11 +3,13 @@ package inbound
 import (
 	"bytes"
 	"context"
+	"encoding/binary"
 	"encoding/json"
 	"log"
 	"net"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -26,6 +28,23 @@ type memoryRecoveryStore struct {
 	completed []DownstreamRecoveryStatus
 }
 
+type synchronizedBuffer struct {
+	mu     sync.Mutex
+	buffer bytes.Buffer
+}
+
+func (b *synchronizedBuffer) Write(data []byte) (int, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buffer.Write(data)
+}
+
+func (b *synchronizedBuffer) String() string {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buffer.String()
+}
+
 func (m *memoryPresenceStore) TouchAccount(_ context.Context, snapshot DownstreamPresence) error {
 	if m.snapshots == nil {
 		m.snapshots = map[string]DownstreamPresence{}
@@ -181,6 +200,33 @@ func TestPostIncludesAPIErrorResponseBody(t *testing.T) {
 	}
 }
 
+func TestInboundServerLogsReadUnpackFailure(t *testing.T) {
+	addr := reserveTCPAddr(t)
+	var logs synchronizedBuffer
+	go func() {
+		_ = (Server{Addr: addr, LogWriter: &logs}).ListenAndServe()
+	}()
+	time.Sleep(300 * time.Millisecond)
+
+	conn, err := net.DialTimeout("tcp", addr, time.Second)
+	if err != nil {
+		t.Fatalf("connect inbound server: %v", err)
+	}
+	defer conn.Close()
+	if err := binary.Write(conn, binary.BigEndian, uint32(1)); err != nil {
+		t.Fatalf("write invalid packet length: %v", err)
+	}
+
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		if strings.Contains(logs.String(), "read/unpack packet failed") && strings.Contains(logs.String(), "total_length") {
+			return
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	t.Fatalf("missing read/unpack failure log: %s", logs.String())
+}
+
 func TestNormalizeInboundSubmitSupportsCMPP2AndCMPP3(t *testing.T) {
 	tests := []struct {
 		name     string