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fix: Don't send uplinks when connection isn't established #58

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Merged
YuKitsune merged 1 commit into from
Sep 6, 2026
Merged

fix: Don't send uplinks when connection isn't established #58

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77 changes: 17 additions & 60 deletions source/CPDLCServer.Tests/Handlers/DownlinkReceivedNotificationHandlerTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,17 +14,13 @@ public class DownlinkReceivedNotificationHandlerTests
{
static DownlinkReceivedNotificationHandler BuildHandler(
TestAircraftRepository aircraftRepository,
TestClientManager clientManager,
TestMessageIdProvider messageIdProvider,
IMediator mediator,
TestClock clock,
TestControllerRepository controllerRepository,
TestDialogueRepository dialogueRepository,
IHubContext<ControllerHub> hubContext) =>
new(
aircraftRepository,
clientManager,
messageIdProvider,
mediator,
clock,
controllerRepository,
Expand Down Expand Up @@ -65,10 +61,8 @@ public async Task Handle_PublishesDialogueChangedNotification()
hubContext.Clients.Clients(Arg.Any<IReadOnlyList<string>>()).Returns(clientProxy);

var dialogueRepository = new TestDialogueRepository();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftManager, clientManager, messageIdProvider, mediator, clock, controllerManager, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftManager, mediator, clock, controllerManager, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
1,
Expand Down Expand Up @@ -124,10 +118,8 @@ public async Task Handle_StillCreatesDialogueWhenNoControllersMatch()
hubContext.Clients.Clients(Arg.Any<IReadOnlyList<string>>()).Returns(clientProxy);

var dialogueRepository = new TestDialogueRepository();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftManager, clientManager, messageIdProvider, mediator, clock, controllerManager, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftManager, mediator, clock, controllerManager, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
1,
Expand Down Expand Up @@ -179,10 +171,8 @@ public async Task Handle_PromotesAircraftToCurrentDataAuthorityOnFirstDownlink()
hubContext.Clients.Clients(Arg.Any<IReadOnlyList<string>>()).Returns(clientProxy);

var dialogueRepository = new TestDialogueRepository();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftManager, clientManager, messageIdProvider, mediator, clock, controllerManager, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftManager, mediator, clock, controllerManager, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
1,
Expand Down Expand Up @@ -253,10 +243,8 @@ public async Task Handle_DoesNotPromoteToCurrentDataAuthority_WhenNotCurrentData
hubContext.Clients.Clients(Arg.Any<IReadOnlyList<string>>()).Returns(clientProxy);

var dialogueRepository = new TestDialogueRepository();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftManager, clientManager, messageIdProvider, mediator, clock, controllerManager, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftManager, mediator, clock, controllerManager, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
1,
Expand Down Expand Up @@ -321,10 +309,8 @@ public async Task Handle_UpdatesLastSeen()
clock.SetUtcNow(expectedLastSeen);

var dialogueRepository = new TestDialogueRepository();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftManager, clientManager, messageIdProvider, mediator, clock, controllerManager, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftManager, mediator, clock, controllerManager, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
1,
Expand Down Expand Up @@ -365,10 +351,8 @@ public async Task Handle_CreatesNewDialogue_ForDownlinkWithNoReference()
var dialogueRepository = new TestDialogueRepository();
var mediator = Substitute.For<IMediator>();
var hubContext = Substitute.For<IHubContext<ControllerHub>>();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftRepository, clientManager, messageIdProvider, mediator, clock, controllerRepository, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftRepository, mediator, clock, controllerRepository, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
1,
Expand Down Expand Up @@ -409,8 +393,6 @@ public async Task Handle_AppendsToExistingDialogue_ForDownlinkWithReference()
var dialogueRepository = new TestDialogueRepository();
var mediator = Substitute.For<IMediator>();
var hubContext = Substitute.For<IHubContext<ControllerHub>>();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

// Create existing dialogue with an uplink
var existingDialogue = new Dialogue("UAL123");
Expand All @@ -425,7 +407,7 @@ public async Task Handle_AppendsToExistingDialogue_ForDownlinkWithReference()
clock.UtcNow());
await dialogueRepository.Add(existingDialogue, CancellationToken.None);

var handler = BuildHandler(aircraftRepository, clientManager, messageIdProvider, mediator, clock, controllerRepository, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftRepository, mediator, clock, controllerRepository, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
10,
Expand Down Expand Up @@ -468,10 +450,8 @@ public async Task Handle_FallsBackToNewDialogue_WhenNoOpenDialogueMatchesReferen
var dialogueRepository = new TestDialogueRepository();
var mediator = Substitute.For<IMediator>();
var hubContext = Substitute.For<IHubContext<ControllerHub>>();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftRepository, clientManager, messageIdProvider, mediator, clock, controllerRepository, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftRepository, mediator, clock, controllerRepository, dialogueRepository, hubContext);

// Downlink has a MessageReference (uplink ID=99) but no open dialogue exists for it
var downlink = new ReceivedDownlink(
Expand Down Expand Up @@ -518,8 +498,6 @@ public async Task Handle_DoesNotAppendToClosedDialogue_WhenAircraftReusesMessage
var dialogueRepository = new TestDialogueRepository();
var mediator = Substitute.For<IMediator>();
var hubContext = Substitute.For<IHubContext<ControllerHub>>();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

// Prior session: uplink ID=5 was sent and fully replied to (dialogue is now closed)
var priorDialogue = new Dialogue("UAL123");
Expand All @@ -535,7 +513,7 @@ public async Task Handle_DoesNotAppendToClosedDialogue_WhenAircraftReusesMessage

Assert.True(priorDialogue.IsClosed);

var handler = BuildHandler(aircraftRepository, clientManager, messageIdProvider, mediator, clock, controllerRepository, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftRepository, mediator, clock, controllerRepository, dialogueRepository, hubContext);

// New session: aircraft re-uses MessageReference=5 (same uplink ID as in the old session)
var downlink = new ReceivedDownlink(
Expand Down Expand Up @@ -578,10 +556,8 @@ public async Task Handle_LogoffMessage_TerminatesConnectionAndCreatesDialogue()
var dialogueRepository = new TestDialogueRepository();
var mediator = Substitute.For<IMediator>();
var hubContext = Substitute.For<IHubContext<ControllerHub>>();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftRepository, clientManager, messageIdProvider, mediator, clock, controllerRepository, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftRepository, mediator, clock, controllerRepository, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
1, null, "UAL123",
Expand Down Expand Up @@ -620,10 +596,8 @@ public async Task Handle_LogonRequest_DispatchesLogonCommand()
var dialogueRepository = new TestDialogueRepository();
var mediator = Substitute.For<IMediator>();
var hubContext = Substitute.For<IHubContext<ControllerHub>>();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftRepository, clientManager, messageIdProvider, mediator, clock, controllerRepository, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftRepository, mediator, clock, controllerRepository, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
1,
Expand Down Expand Up @@ -655,21 +629,19 @@ await mediator.Received(1).Send(
}

[Fact]
public async Task Handle_UnknownAircraft_CreatesDialogueAndTransmitsError()
public async Task Handle_UnknownAircraft_IgnoresDownlink()
{
// Branch 2: a downlink arrives from an aircraft we have no connection for. The handler
// creates a dialogue (downlink + system error uplink) and transmits the error via ACARS.
// ignores it. We do not send messages to an aircraft that has no connection.
// Arrange
var clock = new TestClock();
var aircraftRepository = new TestAircraftRepository();
var controllerRepository = new TestControllerRepository();
var dialogueRepository = new TestDialogueRepository();
var mediator = Substitute.For<IMediator>();
var hubContext = Substitute.For<IHubContext<ControllerHub>>();
var clientManager = new TestClientManager();
var messageIdProvider = new TestMessageIdProvider();

var handler = BuildHandler(aircraftRepository, clientManager, messageIdProvider, mediator, clock, controllerRepository, dialogueRepository, hubContext);
var handler = BuildHandler(aircraftRepository, mediator, clock, controllerRepository, dialogueRepository, hubContext);

var downlink = new ReceivedDownlink(
7,
Expand All @@ -685,25 +657,10 @@ public async Task Handle_UnknownAircraft_CreatesDialogueAndTransmitsError()
// Act
await handler.Handle(notification, CancellationToken.None);

// Assert - dialogue contains both the original downlink and the error uplink
// Assert - no dialogue created and nothing published
var dialogues = await dialogueRepository.All(CancellationToken.None);
Assert.Single(dialogues);
Assert.Equal("GHOST1", dialogues[0].AircraftCallsign);
Assert.Equal(2, dialogues[0].Messages.Count);

var receivedDownlink = Assert.IsType<DownlinkMessage>(dialogues[0].Messages[0]);
Assert.Equal(7, receivedDownlink.MessageId);

var errorUplink = Assert.IsType<UplinkMessage>(dialogues[0].Messages[1]);
Assert.Equal("ERROR. CONNECTION NOT ESTABLISHED.", errorUplink.Content);
Assert.Equal("GHOST1", errorUplink.Recipient);
Assert.Equal(7, errorUplink.MessageReference);

// Assert - error uplink transmitted via the ACARS client
var client = (TestAcarsClient)await clientManager.GetAcarsClient("hoppies-ybbb", CancellationToken.None);
Assert.Single(client.SentMessages);
Assert.Equal("ERROR. CONNECTION NOT ESTABLISHED.", client.SentMessages[0].Content);
Assert.Empty(dialogues);

await mediator.Received(1).Publish(Arg.Any<DialogueChangedNotification>(), Arg.Any<CancellationToken>());
await mediator.DidNotReceive().Publish(Arg.Any<DialogueChangedNotification>(), Arg.Any<CancellationToken>());
}
}
47 changes: 1 addition & 46 deletions source/CPDLCServer/Handlers/DownlinkReceivedNotificationHandler.cs
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Original file line number Diff line number Diff line change
@@ -1,19 +1,15 @@
using CPDLCServer.Clients;
using CPDLCServer.Hubs;
using CPDLCServer.Infrastructure;
using CPDLCServer.Messages;
using CPDLCServer.Model;
using CPDLCServer.Persistence;
using CPDLCServer.Services;
using MediatR;
using Microsoft.AspNetCore.SignalR;

namespace CPDLCServer.Handlers;

public class DownlinkReceivedNotificationHandler(
IAircraftRepository aircraftRepository,
IClientManager clientManager,
IMessageIdProvider messageIdProvider,
IMediator mediator,
IClock clock,
IControllerRepository controllerRepository,
Expand Down Expand Up @@ -51,8 +47,7 @@ await mediator.Send(
// Scenario 2: Unknown aircraft
if (aircraftConnection is null)
{
logger.Information("{Callsign} is not known by this ATSU, sending error uplink", downlink.Sender);
await SendUnknownAircraftError(notification, downlink, cancellationToken);
logger.Information("{Callsign} is not known by this ATSU, ignoring downlink", downlink.Sender);
return;
}

Expand Down Expand Up @@ -143,44 +138,4 @@ await hubContext.Clients
await mediator.Publish(new DialogueChangedNotification(dialogue), cancellationToken);
}
}

async Task SendUnknownAircraftError(
DownlinkReceivedNotification notification,
ReceivedDownlink downlink,
CancellationToken cancellationToken)
{
var dialogue = new Dialogue(downlink.Sender);
dialogue.AddDownlink(
downlink.MessageId,
downlink.MessageReference,
downlink.Sender,
downlink.ResponseType,
downlink.AlertType,
downlink.Content,
downlink.Received);

var messageId = await messageIdProvider.GetNextMessageId(
notification.AcarsClientId,
downlink.Sender,
cancellationToken);

var uplinkMessage = dialogue.AddUplink(
messageId,
downlink.MessageId,
downlink.Sender,
"SYSTEM",
CpdlcUplinkResponseType.NoResponse,
AlertType.None,
"ERROR. CONNECTION NOT ESTABLISHED.",
clock.UtcNow());

await dialogueRepository.Add(dialogue, cancellationToken);
logger.Information("Dialogue {DialogueId} created for unknown aircraft {Callsign}", dialogue.Id, downlink.Sender);

await mediator.Publish(new DialogueChangedNotification(dialogue), cancellationToken);

var client = await clientManager.GetAcarsClient(notification.AcarsClientId, cancellationToken);
await client.Send(uplinkMessage, cancellationToken);
logger.Information("Sent CPDLC message from SYSTEM to {Callsign}", downlink.Sender);
}
}
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