Public Access
Say when a vault has moved, so nobody waits out the minute
The delta pull was cheap enough to run on a timer and the client did, once a minute. That is fine for a machine and wrong for two people: an edit a colleague makes is up to a minute stale, which is long enough for both of them to make it and produce a conflict neither needed to have. Shortening the interval is the obvious answer and the wrong one — it costs a request per client per interval whether or not anything happened, and it converges on a busier server that is still late. So the server now says so. A client holds a WebSocket open at GET /api/v1/events, subprotocol dodossh.events.v1, and gets a line down it when something it can read has changed. ADR 0012 has the reasoning; three parts of it are worth repeating here, because they are what everything else rests on. **What crosses the socket is a notice, never data.** A frame names a vault and how far its change log has got. No item, no ciphertext, not even which item it was. The client's answer is the delta pull it would have run anyway, so there is still exactly one code path that applies a change to a keychain, and it is not this one. Pushing the items themselves would save a round trip and fork that path in two, with the cursor, the merge and the tombstone rules duplicated across both — ADR 0003 put every mutation through one write path for that reason, and this keeps every read on one for the same one. It also makes a dropped notice harmless, which is what lets the fan-out below be as simple as it is. **Polling stays, and is what guarantees a pass.** The minute timer is unchanged. A network that eats WebSockets, a server with Events:Enabled off, an older server, a proxy that will not upgrade, a notice dropped under backpressure — every one of those leaves a client behaving exactly as it did before this commit. Nothing is reachable only over the socket and nothing is meant to become so; VaultViewModel's AutoSyncInterval remark now says that where somebody changing it will read it. **The bearer token authorises the upgrade, unlike the relay's ticket.** Not an inconsistency with ADR 0004: the relay's socket is a byte pipe whose whole authorization decision — which host, which IPs, which port — is made before it opens and never revisited, and it is the extraction seam for a process that must hold no ACL code. This one is a view of the caller's own vault list and has to keep answering "what may this account read" for as long as it is held. A ticket would carry that answer in a token and be wrong the moment the account's access changed. The two bounds that arrangement needs are met rather than waved at: the socket is closed at the token's exp with close code 4401 and the client comes straight back with a fresh one, and the vault set is re-resolved every few minutes as well as on the changes known to affect it. Both bound *metadata*, because a notice contains nothing else and reading a vault still needs a key this server has never held. **The fan-out.** VaultEventHub is a singleton holding the sockets this node accepted; publishing walks them and asks each whether it cares, rather than keeping a vault-to-subscriber index that every re-subscription would have to move entries between under a lock publishing also takes. At a few hundred sockets per node and an event rate bounded by how often people edit keychains, the walk is not measurable and its races are obvious. Per-connection queues are bounded and drop the *oldest*: a notice means "pull vault X, which is at least at sequence N", so the newest subsumes what it displaces and the client's answer is identical either way — which is what lets the publish path be void, never block, and never fail. Announced from the endpoint rather than from SyncService, and that placement is the point: by then the push has committed and released the per-vault advisory lock. From inside it would name a sequence no reader can see yet and would hold the lock that serialises writers across a socket write. Only the highest *applied* sequence, so a batch of pure conflicts announces nothing, and a duplicate — already announced when it first landed — announces nothing either. Grants and membership publish too, and those take the *recipient* rather than the actor. This is what AdmitNewVaultsAsync has been apologising for since sharing shipped — "the recipient is handed nothing, there is no push channel" — and the README with it. A vault shared with somebody now turns up as it is shared. The comment and the README paragraph both say what is true now, and both keep saying that the pass is what *discovers* the vault, because a client with no socket has to arrive at the same place. **On the client**, VaultEventStream is really a reconnection policy wrapped round a ClientWebSocket: a dropped socket is the ordinary case here — laptops sleep, proxies time out, tokens expire, servers are redeployed — so nothing in it treats a failure as exceptional, and every path ends in "wait, then dial again". A connection that lived long enough to say hello resets the backoff, so a laptop that woke, worked, and lost its network an hour later does not inherit a minute-long wait it has already proved it need not take. A 4401 close skips the backoff entirely and asks the token provider again, which is the whole reason that close code is distinct. A server that does not advertise the events feature gets IdleVaultEventStream, which never delivers — so IVaultServer.Events is never null and every caller stays on one shape, because the correct behaviour without a socket is the behaviour with a silent one. The shell's background loop now selects between the timer and a notice, and both waits are held across iterations. That is load-bearing rather than tidy: PeriodicTimer permits one outstanding WaitForNextTickAsync and throws on a second, and an abandoned channel read stays registered and consumes the next notice written. Either defect leaves the first notice working and every one after it silently lost, which is why NoticesKeepWakingTheLoop_NotJustTheFirst pushes three and not one. Notices are coalesced over a quarter of a second, so one person's save — a host and its log entry are two items — and a colleague clearing a folder each cost one pass rather than a dozen. **The kind is a string, not an enum**, and that is a compatibility decision. UseStringEnumConverter throws on a value it does not know, so a newer server sending a kind an older client had never heard of would not add an unreadable frame — it would break that client's socket outright. A string is ignored instead. ProblemCodes is the same shape for the same reason. **Tested on both sides, through the real pipeline.** The endpoint suite opens a genuine socket against TestServer and proves a push produces a notice, that another account's push does not reach it, that a ping is answered, and that a frame this server cannot parse does not end the connection. Two of those assert on *ordering* rather than on absence within a timeout — the stranger's write goes first, so a socket that leaked would have announced it before the one the test waits for — because "nothing arrived in two seconds" is a test that passes on a slow machine for the wrong reason. And ANoticeCarriesNoCiphertext asserts on the bytes that crossed the wire rather than on the record's fields, since the latter would only prove that this type has no payload member, which is a tautology; the former is what catches a field added later without anybody thinking about disclosure. The client suite drives VaultEventStream through an injected connector, because the one thing a test cannot do to a real network is make it fail on cue — and failure is the entire subject. The shell suite proves a notice produces a pull inside ten seconds against a sixty-second timer, so the timer cannot be what caused it. **Two limits, stated rather than left to be discovered.** Fan-out is in-process, so a deployment running more than one API replica only pushes for writes its own replica handled and the rest arrive on the timer. IVaultEventPublisher is the seam a PostgreSQL LISTEN/NOTIFY backplane implements and it is deliberately not implemented: an untested backplane is worse than a documented gap, and multiple replicas degrade to the behaviour before this commit rather than breaking. And a client is notified of its own writes; it pushed, so it already pulled, and the extra pass finds nothing. Suppressing that echo correctly needs a per-device identity on the socket, and the same user's other machines must still be told. Manual checks phase 15 covers what no test here can reach, which is the network in between: a proxy that will not upgrade, one that drops an idle socket without telling either end, a laptop lid, a token expiring. Every one of those is invisible inside a test host, and every check there passes only if the change arrives quickly *and* still arrives with the socket taken away. ADR 0012 also fixes one thing about the shared terminal session this is the transport for, so it need not be renegotiated later: session data will be binary frames on this same socket, because base64 in a JSON envelope is the wrong shape for the one payload here that is continuous rather than occasional. Two questions it explicitly does not answer by implication — whether those bytes go through the API at all, and what end-to-end encryption means when the second party watches a stream rather than holding a key — are ADR 0001 questions and get their own decision. 1512 tests pass. DodoSSH.SystemTests was not run — it needs the whole compose stack — so the end-to-end path is unverified for this change beyond what the manual checks describe.
This commit is contained in:
@@ -0,0 +1,388 @@
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using System.Net.WebSockets;
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using System.Text;
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using System.Text.Json;
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using System.Threading.Channels;
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using DodoSSH.Client.Api;
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using DodoSSH.Contracts;
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namespace DodoSSH.Client.Api.Tests;
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/// <summary>
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/// The reconnection policy, which is what this class actually is.
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/// </summary>
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/// <remarks>
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/// <para>
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/// A dropped socket is the ordinary case here rather than the exception — laptops sleep, proxies time
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/// out, tokens expire, servers are redeployed — so the behaviour worth covering is what happens
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/// <em>after</em> a failure, not the happy path. Driven through the injected connector, because the one
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/// thing a test cannot do to a real network is make it fail on cue.
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/// </para>
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/// <para>
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/// The backoff is configured down to milliseconds throughout. What is under test is the shape of the
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/// policy — does it try again, does it wait, does it stop waiting when told the token was the problem —
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/// and none of that depends on the intervals a shipped client uses.
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/// </para>
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/// </remarks>
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public sealed class VaultEventStreamTests
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{
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private static readonly Uri Server = new("https://dodossh.example");
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private static readonly VaultEventStreamOptions Impatient = new()
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{
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InitialBackoff = TimeSpan.FromMilliseconds(1),
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MaxBackoff = TimeSpan.FromMilliseconds(5),
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InitialSilenceTimeout = TimeSpan.FromSeconds(30),
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};
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[Fact]
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public async Task ItDialsTheWebSocketFormOfTheServersUrl()
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{
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// https becomes wss, and the path is the one in the contract. Getting either wrong is a client
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// that reconnects against a 404 for the whole session, which from outside is indistinguishable
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// from a network that eats WebSockets.
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var dialled = new List<Uri>();
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var socket = new FakeWebSocket();
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await using var stream = Stream(
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(url, _, _) =>
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{
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dialled.Add(url);
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return Task.FromResult<WebSocket>(socket);
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});
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 1));
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await stream.ReadAsync(Token);
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dialled[0].ShouldBe(new Uri("wss://dodossh.example/api/v1/events"));
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}
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[Fact]
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public async Task ItSendsTheBearerTokenOnTheUpgrade()
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{
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// The whole of this socket's authorization, unlike the relay's ticket. See ADR 0012.
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var presented = new List<string>();
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var socket = new FakeWebSocket();
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await using var stream = Stream(
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(_, token, _) =>
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{
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presented.Add(token);
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return Task.FromResult<WebSocket>(socket);
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});
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 1));
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await stream.ReadAsync(Token);
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presented[0].ShouldBe(StubTokens.Token);
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}
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[Fact]
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public async Task ANoticeReachesTheReader()
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{
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var vaultId = Guid.CreateVersion7();
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var socket = new FakeWebSocket();
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await using var stream = Stream((_, _, _) => Task.FromResult<WebSocket>(socket));
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, vaultId, 42));
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var notice = await stream.ReadAsync(Token);
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notice.Kind.ShouldBe(VaultEventKinds.VaultChanged);
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notice.VaultId.ShouldBe(vaultId);
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notice.Sequence.ShouldBe(42);
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}
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[Fact]
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public async Task AHeartbeatIsAnsweredAndNotHandedToTheReader()
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{
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// A ping is housekeeping between the two ends. Passing it up would wake a synchronisation loop
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// every thirty seconds for a frame that says nothing happened.
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var socket = new FakeWebSocket();
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await using var stream = Stream((_, _, _) => Task.FromResult<WebSocket>(socket));
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socket.Deliver(new VaultEvent(VaultEventKinds.Ping, HeartbeatSeconds: 30));
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 1));
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var first = await stream.ReadAsync(Token);
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first.Kind.ShouldBe(VaultEventKinds.VaultChanged, "the ping should not have been forwarded");
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var answered = await socket.SentAsync(Token);
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answered.Kind.ShouldBe(VaultEventKinds.Pong);
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}
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[Fact]
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public async Task AKindThisBuildDoesNotKnow_IsStillHandedOver()
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{
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// What makes the frame table extensible: this class must not decide what a newer server may
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// say. Deciding to ignore it is the caller's, and costs that caller one redundant pass.
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var socket = new FakeWebSocket();
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await using var stream = Stream((_, _, _) => Task.FromResult<WebSocket>(socket));
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socket.Deliver(new VaultEvent("session.offered"));
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var notice = await stream.ReadAsync(Token);
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notice.Kind.ShouldBe("session.offered");
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}
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[Fact]
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public async Task AFailedDial_IsRetried()
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{
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// No server yet, or no network. Neither is an error to report: the caller's synchronisation
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// timer is running regardless, which is what lets this stay silent and keep trying.
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var attempts = 0;
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var socket = new FakeWebSocket();
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await using var stream = Stream((_, _, _) =>
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{
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if (++attempts < 3)
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{
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throw new WebSocketException("no route to host");
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}
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return Task.FromResult<WebSocket>(socket);
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});
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 1));
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var notice = await stream.ReadAsync(Token);
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notice.Kind.ShouldBe(VaultEventKinds.VaultChanged);
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attempts.ShouldBe(3);
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}
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[Fact]
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public async Task ADroppedSocket_IsReplaced()
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{
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// The case that decides whether this feature survives a laptop lid. A stream that gave up on
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// the first close would work all morning and be silently dead after lunch.
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var sockets = new List<FakeWebSocket>();
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await using var stream = Stream((_, _, _) =>
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{
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var socket = new FakeWebSocket();
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sockets.Add(socket);
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if (sockets.Count == 1)
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{
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 1));
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socket.Close(WebSocketCloseStatus.EndpointUnavailable);
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}
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else
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{
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 2));
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}
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return Task.FromResult<WebSocket>(socket);
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});
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(await stream.ReadAsync(Token)).Sequence.ShouldBe(1);
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(await stream.ReadAsync(Token)).Sequence.ShouldBe(2);
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sockets.Count.ShouldBeGreaterThanOrEqualTo(2);
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}
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[Fact]
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public async Task AnExpiredTokenClose_ReconnectsAndAsksForAFreshToken()
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{
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// The bound that lets a long-lived socket be authorised by a short-lived credential: the server
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// closes at the token's expiry and the client comes straight back with a new one. The token
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// provider being asked again is the half that matters — reconnecting with the spent token would
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// be an unbroken loop of closes.
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var tokens = new StubTokens();
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var sockets = 0;
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await using var stream = new VaultEventStream(
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Server,
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tokens,
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TimeProvider.System,
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(_, _, _) =>
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{
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var socket = new FakeWebSocket();
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if (++sockets == 1)
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{
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socket.Close((WebSocketCloseStatus)VaultEvents.TokenExpiredCloseCode);
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}
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else
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{
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 7));
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}
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return Task.FromResult<WebSocket>(socket);
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},
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Impatient);
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(await stream.ReadAsync(Token)).Sequence.ShouldBe(7);
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tokens.Requests.ShouldBeGreaterThanOrEqualTo(2);
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}
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[Fact]
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public async Task TryRead_TakesWhatIsWaitingAndSaysWhenNothingIs()
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{
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// How a caller coalesces a burst: read one, wait a moment, swallow the rest. Without this a
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// colleague tidying a folder would produce a synchronisation pass per item.
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var socket = new FakeWebSocket();
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await using var stream = Stream((_, _, _) => Task.FromResult<WebSocket>(socket));
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 1));
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socket.Deliver(new VaultEvent(VaultEventKinds.VaultChanged, Guid.CreateVersion7(), 2));
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(await stream.ReadAsync(Token)).Sequence.ShouldBe(1);
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// Delivery is asynchronous, so the second may not have landed yet; this is the same
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// wait-then-drain the caller performs.
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await Task.Delay(TimeSpan.FromMilliseconds(200), Token);
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stream.TryRead(out var queued).ShouldBeTrue();
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queued.Sequence.ShouldBe(2);
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stream.TryRead(out _).ShouldBeFalse();
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}
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[Fact]
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public async Task AnIdleStream_NeverDelivers()
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{
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// What a server without the feature supplies. Waiting for ever rather than completing is the
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// point: a caller selecting between this and a timer has to fall through to the timer, and a
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// read that returned at once would spin that loop as fast as the machine allows.
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using var stream = IdleVaultEventStream.Instance;
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using var giveUp = CancellationTokenSource.CreateLinkedTokenSource(Token);
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giveUp.CancelAfter(TimeSpan.FromMilliseconds(100));
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await Should.ThrowAsync<OperationCanceledException>(
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async () => await stream.ReadAsync(giveUp.Token));
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stream.TryRead(out _).ShouldBeFalse();
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stream.IsConnected.ShouldBeFalse();
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}
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private static CancellationToken Token => TestContext.Current.CancellationToken;
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private static VaultEventStream Stream(
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Func<Uri, string, CancellationToken, Task<WebSocket>> connect) =>
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new(Server, new StubTokens(), TimeProvider.System, connect, Impatient);
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/// <summary>A token provider that hands out one value and counts who asked.</summary>
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private sealed class StubTokens : IAccessTokenProvider
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{
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internal const string Token = "access-token";
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internal int Requests { get; private set; }
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public ValueTask<string> GetAccessTokenAsync(CancellationToken cancellationToken)
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{
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Requests++;
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return ValueTask.FromResult(Token);
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}
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}
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/// <summary>
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/// A socket a test writes the server's half of.
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/// </summary>
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/// <remarks>
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/// Frames queued with <see cref="Deliver"/> are handed out by <see cref="ReceiveAsync"/> in order;
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/// once the queue is empty the receive waits, which is what an idle connection does. <see
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/// cref="Close"/> queues the close instead, so a test can script "two notices and then the server
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/// went away" as a value rather than as a race.
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/// </remarks>
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private sealed class FakeWebSocket : WebSocket
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{
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private readonly Channel<byte[]> inbound = Channel.CreateUnbounded<byte[]>();
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private readonly Channel<VaultEvent> outbound = Channel.CreateUnbounded<VaultEvent>();
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private WebSocketCloseStatus? closing;
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private WebSocketState state = WebSocketState.Open;
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public override WebSocketCloseStatus? CloseStatus => closing;
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public override string? CloseStatusDescription => null;
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public override WebSocketState State => state;
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public override string? SubProtocol => VaultEvents.SubProtocol;
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/// <summary>Queues a frame for the client to read.</summary>
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internal void Deliver(VaultEvent frame) =>
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inbound.Writer.TryWrite(
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JsonSerializer.SerializeToUtf8Bytes(frame, DodoSshJsonContext.Default.VaultEvent));
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/// <summary>Ends the socket, after everything already queued has been read.</summary>
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internal void Close(WebSocketCloseStatus status)
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{
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closing = status;
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inbound.Writer.TryWrite([]);
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}
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/// <summary>The next frame the client sent.</summary>
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internal ValueTask<VaultEvent> SentAsync(CancellationToken cancellationToken) =>
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outbound.Reader.ReadAsync(cancellationToken);
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public override async Task<WebSocketReceiveResult> ReceiveAsync(
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ArraySegment<byte> buffer,
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CancellationToken cancellationToken)
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{
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var frame = await inbound.Reader.ReadAsync(cancellationToken);
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// The empty frame Close queues. Reported as a close, exactly as a real socket does once the
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// peer's close frame arrives.
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if (frame.Length == 0)
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{
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state = WebSocketState.Closed;
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return new WebSocketReceiveResult(
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0, WebSocketMessageType.Close, endOfMessage: true, closing, null);
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}
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frame.CopyTo(buffer.Array!, buffer.Offset);
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return new WebSocketReceiveResult(frame.Length, WebSocketMessageType.Text, endOfMessage: true);
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}
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public override Task SendAsync(
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ArraySegment<byte> buffer,
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WebSocketMessageType messageType,
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bool endOfMessage,
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CancellationToken cancellationToken)
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{
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var json = Encoding.UTF8.GetString(buffer.Array!, buffer.Offset, buffer.Count);
|
||||
|
||||
if (JsonSerializer.Deserialize(json, DodoSshJsonContext.Default.VaultEvent) is { } frame)
|
||||
{
|
||||
outbound.Writer.TryWrite(frame);
|
||||
}
|
||||
|
||||
return Task.CompletedTask;
|
||||
}
|
||||
|
||||
public override void Abort() => state = WebSocketState.Aborted;
|
||||
|
||||
public override Task CloseAsync(
|
||||
WebSocketCloseStatus closeStatus,
|
||||
string? statusDescription,
|
||||
CancellationToken cancellationToken) => CloseOutputAsync(
|
||||
closeStatus, statusDescription, cancellationToken);
|
||||
|
||||
public override Task CloseOutputAsync(
|
||||
WebSocketCloseStatus closeStatus,
|
||||
string? statusDescription,
|
||||
CancellationToken cancellationToken)
|
||||
{
|
||||
state = WebSocketState.Closed;
|
||||
|
||||
return Task.CompletedTask;
|
||||
}
|
||||
|
||||
public override void Dispose() => state = WebSocketState.Closed;
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user