fix(ws): raise bounded agent message limit

internal/agent/wsclient/client_test.go

@@ -2,12 +2,16 @@ package wsclient
 
 import (
 	"context"
+	"encoding/json"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 	"time"
 
 	"github.com/coder/websocket"
+
+	"gitea.dcglab.co.uk/steve/restic-manager/internal/api"
 )
 
 func TestConnectOnceCleanDisconnectDoesNotPanic(t *testing.T) {
@@ -44,3 +48,56 @@ func TestConnectOnceCleanDisconnectDoesNotPanic(t *testing.T) {
 		t.Fatalf("server websocket: %v", err)
 	}
 }
+
+func TestConnectOnceAcceptsMessageLargerThanDefaultReadLimit(t *testing.T) {
+	received := make(chan struct{}, 1)
+	serverErr := make(chan error, 1)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		conn, err := websocket.Accept(w, r, nil)
+		if err != nil {
+			serverErr <- err
+			return
+		}
+		defer conn.CloseNow() //nolint:errcheck
+		if _, _, err := conn.Read(r.Context()); err != nil {
+			serverErr <- err
+			return
+		}
+		env := api.Envelope{
+			Type:    api.MsgConfigUpdate,
+			Payload: json.RawMessage(`{"padding":"` + strings.Repeat("x", 40*1024) + `"}`),
+		}
+		raw, _ := json.Marshal(env)
+		serverErr <- conn.Write(r.Context(), websocket.MessageText, raw)
+		<-r.Context().Done()
+	}))
+	defer srv.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	done := make(chan error, 1)
+	go func() {
+		done <- connectOnce(ctx, Config{
+			ServerURL:       srv.URL,
+			AgentToken:      "test-token",
+			HeartbeatPeriod: time.Hour,
+		}, func(_ context.Context, env api.Envelope, _ Sender) error {
+			if env.Type == api.MsgConfigUpdate {
+				received <- struct{}{}
+				cancel()
+			}
+			return nil
+		})
+	}()
+
+	select {
+	case <-received:
+	case <-time.After(5 * time.Second):
+		t.Fatal("agent did not receive oversized server message")
+	}
+	if err := <-serverErr; err != nil {
+		t.Fatalf("server websocket: %v", err)
+	}
+	if err := <-done; err == nil {
+		t.Fatal("connectOnce returned nil")
+	}
+}