Commit Graph
6 Commits
Author SHA1 Message Date
jaap-jan e2733e5cbc Notice when a shell ends, say which way it ended, and offer the way back
ci / build and test (push) Successful in 3m28s
ci / android head (push) Successful in 4m48s
ci / desktop nightly (push) Successful in 1m17s
ci / api image (push) Successful in 28s
A terminal whose machine rebooted stayed green for ever. Not "went stale and
recovered late" — for ever: the tab claimed CONNECTED, the elapsed timer went
on counting, and the only thing that ever corrected it was closing the
application. That is the defect this fixes, and it turned out to be two
separate failures wearing one symptom.

◆ THE HANG IS IN SSH.NET, AND KEEP-ALIVE ALONE WOULD NOT HAVE FIXED IT.

ShellStream ends a blocked read from exactly two places: its channel being
closed, and the session raising Disconnected. A shell that exits gives the
first. But Session raises Disconnected from one method only — OnDisconnectReceived,
for a server that politely says goodbye — and a socket that simply fails goes
down a different path entirely: RaiseError fires the error event, sets the
disconnecting flag and disposes the socket, without ever raising Disconnected.
So the stream was never disposed, its Monitor.Wait was never pulsed, and the
read blocked until the process ended. The transport was gone, the client knew
the transport was gone, and nothing woke the one thread that was waiting.

That is why the first attempt at a test for this sat at thirty seconds and
failed. Both halves are needed and neither is sufficient:

  - Keep-alive makes the failure HAPPEN. An idle SSH session is a socket
    nobody writes to, and TCP has no way to discover that the far end has gone
    without writing to it — nothing was asked, so nothing could fail. Thirty
    seconds, matching OpenSSH's own ServerAliveInterval examples. It is the
    write that matters and not a reply: SSH_MSG_IGNORE need not be answered,
    so this is traffic rather than a heartbeat with a deadline, and there is
    no timeout invented here to be wrong about a slow link.

  - Disposing the stream from the error handler makes it ARRIVE. Queued to the
    thread pool and not done inline, which is not tidiness: this runs on
    SSH.NET's message-listener thread, and closing a channel waits for the
    server's close — processed by that same thread — so an inline dispose is
    the listener thread waiting on itself.

SFTP gets the keep-alive too. Its operations are request/response and bounded
by ConnectionInfo.Timeout already, so it needs no equivalent wake-up.

◆ exit AND reboot ARE TOLD APART BY A LATCH, BECAUSE THE OBVIOUS WAY IS A RACE.

Wait for the read to end and then ask whether the transport is still up, and
against a real server the answer is wrong about half the time: this was the
only channel on the connection, so sshd hangs up a millisecond after closing
it. By the time anything could ask, the transport is gone either way — and a
poll would report every ordinary `exit` as a dropped connection.

So ISshShellSession.TransportFailure is set at the moment SSH.NET raises the
failure, which its own ordering puts strictly before the disconnect that wakes
the read. A read that has just returned zero consults a settled value: set if
the transport failed, still null if the remote merely closed the channel. The
pump turns that into a TerminalSessionOutcome — RemoteClosed, ConnectionLost,
ClosedLocally — carried on SessionEnded, which used to hand over a session id
and nothing else. A subscriber cannot work this out afterwards; by the time it
hears, there is no transport left to interrogate.

Deliberately no fourth value for "the remote rebooted". Nothing on the wire
distinguishes a reboot from a cable being pulled, and a name this client
cannot check would be a guess dressed as a fact.

◆ WHAT IS DRAWN, AND WHY IT IS NOT DRAWN OVER THE PANE.

The status bar says DISCONNECTED or SHELL EXITED where it used to say NOT
CONNECTED for both — a word that is honest about a tab still dialling and
useless about one whose shell has stopped. Red for the first and grey for the
second: one is a machine that stopped answering and the other is work
finished, and crying wolf on the ordinary end of every session is its own bug.
The tab strip's dot gains the same fourth state, on both heads.

Under the terminal, a strip carrying the reason and two buttons. It takes its
own Auto grid row rather than overlaying the renderer, and that is forced
rather than chosen: the WebView is a native child view composited above
everything Avalonia draws, so the alternative is collapsing the terminal — and
the scrollback is precisely what the user wants to read, because the last
thing the remote said is usually why it went. terminal.js already writes the
same sentence into the pane; this is the copy that does not scroll away.

RECONNECT reuses the tab in place, which is what the word means to somebody
who pressed it: the terminal they were working in comes back, where it was.
It dials through the vault's ordinary connect path, so every refusal — a key
that has left the keychain, an unknown host key, a group default that has
changed since — is decided in the one place that already decides them; what
this adds is which tab the attempt belongs to. The old session is closed as
part of it, because a dead shell still holds an authenticated connection this
process has stopped reading, and its pane still holds an xterm, a scrollback
and a WebGL context, of which a browser hands out about sixteen.

Two refusals it makes rather than pretending: a host reached by typing an
address has no keychain entry to redial, and one that wants a password typed
goes to the keychain with the sheet raised rather than being dialled with an
empty box. Both say so on the strip where the button was pressed, not only in
the vault's status on a screen that surface is not.

TRY AGAIN appears on a refused connection for the same reason, and it is worth
as much: the commonest refusal is a host that was not up yet.

◆ WHAT IS ACTUALLY VERIFIED.

Two tests against a real sshd in a container. `exit` is reported as the remote
closing the session — the one a polling implementation fails, and a fake shell
cannot show it because a fake has no server behind it deciding to hang up. And
a live shell losing its transport is reported as a lost connection, produced
by dialling through a plain TCP relay the test owns and then cutting it; the
container is shared by the collection, so killing sshd was never an option.

The first draft of that second test used LoopbackProxyTests' SOCKS forward and
timed out: disconnecting the carrier of a ForwardedPortDynamic does not close
the loopback socket it accepted. Recorded in the test, because it is a
property of SSH.NET's forwarder rather than of anything here, and it is not
what a dying machine looks like.

What no test reproduces is the waiting. A relay that closes sends a FIN, so
the socket reports itself at once; a machine switched off sends nothing, and
finding that out is the keep-alive's business and the OS's retransmit budget's
— neither of which a test can hurry along without a clock this code does not
own. A reboot is prompt in practice because the machine comes back and RSTs.

Beside those: three pump outcomes, three workspace announcements, and seven
shell-flow tests covering the drop, the clean exit, reuse of the tab, retry
after a refusal, and both ways a reconnect can honestly come to nothing.

Also fixed in passing: SshNetShellSession.IsOpen read ShellStream.CanRead,
which is documented as always true — the stream stays readable after disposal
so buffered output can be drained — so it had answered "yes" for every shell
that ever existed. It reads CanWrite now. And MainWindowViewModel's session-
ended handler moved from Dispatcher.UIThread.Post to the injected post
delegate, which is what makes any of the shell half testable at all; the
remark listing the three unreachable posts is one shorter.
2026-08-24 10:36:15 +02:00
jaap-jan 8a77b7ca68 Say how far a connection has got while it is still being made
ci / build and test (pull_request) Failing after 2m34s
ci / desktop nightly (pull_request) Skipped
ci / api image (pull_request) Skipped
ci / android head (pull_request) Successful in 3m28s
The connecting card set its status string once, when the tab was created, and
never touched it again. Every connection therefore looked identical from the
outside: one three seconds into a key exchange, one waiting out a fifteen-second
timeout against a machine that is asleep, and one that had hung all drew the
same "connecting…". The card now draws the five steps of getting there, each lit
at the moment the handshake reports reaching it, over an amber track that fills
as they finish.

◆ NOTHING ON THE LIST IS INVENTED. Every row changes state because a layer below
it said so, at the instant the thing it names actually began.

That is the whole reason it is worth showing, and it is why most of this commit
is plumbing rather than XAML: there was no progress reporting anywhere in the
stack to hook a step list onto, and a card animating plausible progress would
have been indistinguishable from one that had stopped receiving any.

SshConnectionPhase names four phases and deliberately not more. SSH.NET runs the
entire handshake inside one ConnectAsync and raises exactly one event from the
middle of it — HostKeyReceived, once the key exchange has produced a key to show
— so that event is the only interior moment there is to report. Everything
before it is Reaching and everything after it is Authenticating. A fifth phase
in that assembly would have to be a timer, so there is not one. OpeningShell is
reported by TerminalWorkspace instead, because that is where it happens: the
factory's work ends with an authenticated connection, and asking for a
pseudo-terminal on one is a separate round trip. The SFTP path passes null — a
second connection opened behind an already-open shell has nobody watching a step
list for it.

The card's fifth step, "Starting the terminal", is the renderer wait and lives
in the shell rather than in the SSH assembly, which has never heard of a
renderer. On the first connection after a cold start it is a real wait with a
real failure mode of its own — a missing WebView2 runtime — so a list that began
at "reaching the host" would leave the one wait most likely to hang unnamed.

Amber for the step in flight, and that follows the palette's rule rather than
bending it. Green is what is true and purple is what you can press; a step still
happening is neither, and it is exactly the caveat-worth-reading that amber
exists for. Steps behind it go green as they become true. Nothing animates,
which is the argument TransfersScreen.axaml already makes for its own track,
reaching a screen with far more reason to want a spinner: a spinner is furniture
invented to fill a state nobody measured, and these states are measured, so the
track fills to what has finished and then waits there.

A refusal keeps the step it stopped on, in red, with the ones behind it still
green. That is the half a progress bar could not do, and it is the difference
between "that host is not there" and "that host is there and would not have me"
— a question the reason sentence alone frequently does not settle.

The strip's dot goes amber while a tab is connecting, on both heads. It was
grey, and so is a tab whose shell has exited: the two states in that strip with
the least in common, one worth waiting for and one over. PhoneShell's own
comment already recorded half of this — the dot stopped being green before
anything had answered — and this is the other half.

Progress is raised inline rather than through System.Progress<T>, which captures
whatever synchronisation context it was constructed on and posts to it. That
reads like a convenience and is really a second place the marshalling decision
gets made: silently, differently under a test with no context, and out of order
with respect to the failure that follows a phase. The shell marshals once, in
one handler, through a new optional post parameter on MainWindowViewModel — the
same seam TransfersViewModel already uses, and for the reason its own remark
gives. The three Dispatcher.UIThread.Post calls that predate it are the ones
this suite's comments record as out of reach; they are left alone rather than
swept in here.

Both heads draw the list. They differ in one place: Phone.axaml's mono class
sets a colour and a size along with the family, so the caption rule names its
own family instead of composing the two and asking two rules for one Foreground.
The desktop's mono sets the family alone, which is why ConnectingCard does
compose them. Each head also gains SHOW LOGS beside the button that gives up —
the step list is this attempt and the log is every other one, which is what a
connection taking too long actually raises.

Seven tests, and the two that matter most run against the container rather than
a fake: a real handshake reports its phases in order, and a host-key refusal
never claims to have authenticated. A fake asserting what it was written to
assert would have established nothing about either. The rest cover the tab
advancing while the connection is gated, the step a refusal stops on, and a
phase reported after the user has given up on the tab. 1,861 tests, none
failing.

The Android head's layout is not verified by anything. It compiles, and
compiled bindings mean every new binding path resolves, but that project is not
in DodoSSH.slnx, there is no test project for it and no device here — so unlike
the desktop card, whose shapes the layout harness measures, these rows have not
been drawn. Vertical fit is reasoned, not observed.
2026-08-10 15:47:45 +02:00
jaap-jan 4d1f07f253 Replay the live sessions to a renderer that just attached
Each live session gets its credit window reset — the unacknowledged
bytes died with the old page, and their acknowledgement is never
coming — and its SessionOpened frame again, flagged as a replay so the
page can tell a reattach from a genuinely new session. A session whose
shell already ended gets nothing: its scrollback lived only in the page
that is gone, and a frame implying otherwise would lie.

RendererReattached is the seam for what the workspace has no business
owning: the font size and the selected tab live in the shell, which
re-pushes them from its own subscription.
2026-08-09 10:54:29 +02:00
jaap-jan 8209f15741 Let a session's transport say what it negotiated
ISshConnection and ISftpSession both carry Cipher now — the server-to-client
algorithm off SSH.NET's own ConnectionInfo, captured once because a rekey is
not an event that library raises — and TerminalWorkspace.GetSessionFacts hands
that plus the host key's algorithm back per session, without ever handing over
the connection itself. Nothing reads either yet; the status bar that will is
the next commit.
2026-08-08 20:54:14 +02:00
jaap-jan 5a899afd78 Decide what Lock does to a running shell, and say it
Pressing Lock nulled and disposed the vault view model and touched nothing else.
TerminalWorkspace is injected from App.axaml.cs and outlives every lock, so the SSH
connection, the pty and the pump all kept running while the window said "Unlock your
vault" — and since 0500e43 collapsed the WebView while locked, that live session was
invisible as well as unstopped. CloseSessionAsync was reachable in production only from
DisposeAsync, i.e. shutdown. None of this was written down anywhere, so it was neither a
policy nor a bug, which is the actual problem.

Shells now deliberately outlive the lock, and every layer says so.

The reason to prefer this over making Lock a disconnect: locking is what a person does
when they walk away from the machine, which is exactly when a long upgrade, build or
transfer is most likely to be in flight. Ending every shell would make Lock a button that
destroys work, and the predictable response is to stop pressing it and leave the vault
open instead. The idle auto-lock this will grow decides it outright — an unattended
timeout that killed a running job would be worse than the exposure it removes. Closing
the channel also buys less than it looks: the session was authorised at connect time by a
credential the remote verified itself, and no vault key participates in keeping it alive,
so locking cannot retroactively un-authorise it any more than removing a member can.

Stated honestly rather than implied, because the lock screen is what hides it:

- The unlock screen shows how many shells are still connected, and that locking closes
  the vault and not the connections — so a machine still holding authenticated SSH
  channels does not present itself as merely "locked". Shown only when there is something
  to disclose. Quitting is what ends them, and the text admits that.
- The Lock button carries the same thing in a tooltip, since its name implies the
  opposite of what it does to a shell.
- README lists it as a third architecture consequence beside non-retroactive revocation,
  which is the same shape of honest limit; docs/crypto.md §10 records it as a threat-model
  boundary; TerminalWorkspace and LockAsync carry the argument next to the code.

LiveSessionCount deliberately does not count dictionary entries. Nothing removes a
session when the remote closes the channel by itself — RunSessionAsync only drops the
renderer registration — so sessions.Count would report a shell that exited half an hour
ago as still running, on the one screen where a user is deciding whether it is safe to
walk away. A completed Run task is what "the shell is gone" actually looks like. While
locked the number can only fall, since opening a session needs the vault, so a stale
value over-reports rather than under-reports.

Both new tests fail when the policy is reverted: the count test times out against
sessions.Count, and the shell test reports "workspace.LiveSessionCount should be 1 but was
0" when Lock closes sessions. ShellFlowTests also stops building its workspace with a real
SshNetConnectionFactory that nothing ever called, which had made the suite's independence
from the network a coincidence rather than a property.

Verified by hand with a live shell, which nothing had done: a harness mirroring
MainWindow.axaml's 340,* grid with a real NativeWebView, the shipped WebAssets, a real
sshd in a container, and an ISshShellSession decorator recording every window-change the
remote is actually told about. Across lock and unlock, no window-change reached the remote
at all, stty size answered 50 118 before and after, the renderer's own buffer came back
byte for byte with the wrapped line intact, and the session stayed live throughout. A
control run that never hides the WebView behaves identically, so nothing above is startup
or idle behaviour. Keystrokes injected while locked reach nothing: twelve of twelve
SendInput events accepted with the harness confirmed as the foreground window, no probe
character in the remote's output, and a following Ctrl-U answered BEL, so nothing was
queued in the line editor either. A hidden WS_CHILD window is not eligible for keyboard
focus, which is what makes surviving the lock defensible rather than merely convenient.

Correction to a claim made in f80b3d4: terminal.js's guard comment listed "a host that
hides the WebView while the vault is locked" among the paths that reach a degenerate fit.
It does not. Collapsing the control hides a native child window without resizing it, so
the page still reports paneWidth 840 and paneHeight 760 with unchanged cols and rows, no
ResizeObserver callback fires and the fit never runs. Establishing that rather than
assuming it: the same cycle with MINIMUM_FITTABLE_PIXELS patched to 0 — the guard fully
disabled — is equally clean. The guard is still right for minimising and for a splitter
dragged to the edge; it is simply not what makes locking safe, and must not be cited as
though it were.

Recorded, not fixed:

- Nothing closes one terminal from the interface, so a user reading "1 shell is still
  connected" can only act on it by quitting. CloseSessionAsync is tested and correct;
  VaultViewModel discards the session id it would need.
- A session whose remote exits keeps its ISshConnection, and the thread ShellStream parks,
  until the process ends.
- Suspected and seen once: before the harness waited for the window's scale to settle, a
  DPI settle pushed a 2202x1328 pane for a window 1180 logical units wide and a later
  re-push reflowed the wrapped line. Three later runs at RenderScaling 1.00 never showed
  it, so it is filed as a lead, not a finding.
- WebView2 fails to initialise with CO_E_SERVER_EXEC_FAILURE when the host executable
  sits under a very long path. Cost an hour on the harness; relevant to packaging.
2026-07-29 14:44:02 +02:00
jaap-jan eb354bcdd9 Add the SSH session layer and the terminal data plane
The throughput harness the plan requires before any UI, plus the SSH
plumbing under it. 94 new tests, no WebView involved.

Credit-based flow control is what makes `yes` survivable. A terminal renders
at 60 Hz at best while a remote produces output as fast as the network
allows, and the difference has to accumulate somewhere or be refused.
Credit is reserved *before* reading, never after: because the pump cannot
read more than the renderer has room for, the coalescing buffer is bounded
by the window rather than by how fast the remote can talk. When credit runs
out the pump stops reading, SSH's own receive window closes, and the remote
sshd blocks -- backpressure to the source with no custom protocol.

Verified by falsification, not just by passing: with the credit gate removed
three tests fail, including the throughput harness's bounded-memory
assertion. Acknowledgements are clamped because they cross into JavaScript,
where a buggy or hostile page could otherwise claim to have rendered a
gigabyte and talk the host into an unbounded read.

Host key trust is enforced by *failing* the connection rather than
prompting inside the handshake. SSH.NET raises verification synchronously,
so consulting the user there would block the handshake on a UI round trip
and deadlock the first time the prompt needed the UI thread. Unknown host
and changed key become distinct exceptions the caller resolves
asynchronously. A mismatch has no retry path at all: a dialog offering to
continue is how users are trained to click through the one warning that
actually indicates interception. A legitimately rebuilt server is handled by
removing the pin in settings, away from the moment of connecting.

The data plane serves the renderer page from the same loopback listener as
the socket, which makes Origin predictable -- always http://127.0.0.1:{port}
-- where a WebView virtual-host mapping would give a different origin per
backend and nothing to validate. The token is substituted at serve time, so
it never touches disk and never appears in a URL. Being clear about what
that buys: not protection from a process running as this user, which can
read our memory anyway, but from a page in the user's browser attempting
WebSocket connections to loopback ports, which is a real and routine thing.

Two bugs the tests caught. The accept loop handled connections serially, so
an upgraded WebSocket parked it inside the receive loop and every later
request went unanswered -- the page's own script among them. The suite hung
rather than failed, which is how I found it. And SHA-1 is unavoidable here:
RFC 6455 mandates it for Sec-WebSocket-Accept, where it authenticates
nothing. Suppressed narrowly with that reasoning; the alternative,
HttpListener.AcceptWebSocketAsync, throws PlatformNotSupportedException off
Windows.
2026-07-28 21:58:55 +02:00