Commit Graph
6 Commits
Author SHA1 Message Date
jaap-jan 9ead42171c Stop a flooding remote growing the process, and let an ended session go
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The terminal's memory was bounded by an argument that is not true of the SSH
library underneath it, and the whole of CreditWindow's remark was that argument:
the pump stops reading when the renderer falls behind, SSH's own receive window
closes, the remote sshd blocks on write, and the backpressure reaches the process
producing the output. The middle step does not happen. Renci.SshNet's
Channels.Channel.OnData calls its window adjustment before it raises DataReceived
and re-opens the channel window as soon as it drops below one packet, and
ShellStream's own handler copies the bytes into a System.Net.ArrayBuffer without
blocking and without a ceiling — a buffer that doubles on demand and is not given
back until the stream is disposed. So a reader that stopped reading slowed the
remote down by nothing at all. It only chose whose buffer the flood landed in,
and it chose the one nothing bounds.

Measured against the container this repository already runs sshd in: a reader
that reads nothing while `yes` runs leaves ShellStream holding 8.9 MB after one
second, 26.8 MB after three and 44.3 MB after five, its capacity stepping 16 → 32
→ 64 MB. That is the report of "a massive memory leak on Windows"; it is not a
Windows fault, it is simply where long sessions with heavy output live.

The fix is to read continuously, which is what keeps SSH.NET's buffer empty, and
to put the bound where it can actually be enforced. OutputBacklog is that bound:
a byte-capped queue of unsent output, 4 MiB by default, which drops its oldest
bytes when full and counts what it discarded. Oldest rather than newest, because
the tail of a flood is the prompt somebody is waiting for.

The two bounds are now separate and each is enforced where it means something.
The backlog bounds what is waiting to be sent. The credit window goes on bounding
what has been sent and not yet drawn — the queue inside the WebView that nothing
on this side can measure — and is reserved against in the flush loop rather than
the read loop. Reading is part of neither, because reading was never what the
remote was waiting on.

Dropping is announced rather than silent. A terminal quietly showing a different
transcript from the one the remote sent is worse than one that says it could not
keep up, because the second can be believed. The line goes out under its own
opcode, TerminalServerOpcode.OutputDropped, rather than spliced into the output
stream: what this application says about the transcript is not part of the
transcript, and keeping them apart is also what makes the arithmetic hold — every
byte read is either in an Output payload or counted in BytesDropped. It opens
with an SGR reset, because the cut lands at an arbitrary offset and whatever
escape sequence the remote was in the middle of has been left half-said.

Frames are now capped at 64 KiB and taken straight into the frame buffer. The cap
is the large-object-heap threshold rather than a guess — a quarter-megabyte array
allocated sixty times a second is collected only by a generation 2 pass — and the
direct take removes an allocation and a copy of every byte the terminal shows.

The second half is the one that made the first half's cost persist. Nothing gave
a session back when the remote hung up: TerminalWorkspace kept the entry, and
with it an undisposed ISshConnection — an authenticated socket, its cipher state,
and a keep-alive putting a packet on the wire every thirty seconds — plus the
pump and SSH.NET's read buffer at whatever size the session's busiest moment had
grown it to, for as long as the tab stayed open. A tab somebody typed `exit` into
an hour ago was indistinguishable from a live one in everything except what it
drew. ReleaseAsync disposes both, from AnnounceEndedAsync and after the
announcement: the tab is told first, because tearing down an SSH connection in
front of that would be latency on the one thing the user is watching for. The
dictionary entry stays, because LiveSessionCount, IsSessionLive and the tab's own
ENDED and RECONNECT all read it. SendInputAsync therefore asks about liveness
rather than presence, since the shell channel is gone the moment the remote is.

Two faults introduced on the way here and fixed, both worth naming because
neither would have been visible from the outside:

The read loop left through a condition on its cancellation token, and RunAsync
reads a read loop that returns as the remote having closed the channel. A tab the
user closed would have reported itself as a shell that exited on its own. It
throws instead.

With the reader finished and a renderer that had stopped acknowledging, the flush
loop span: output to send, no credit to send it with, and a wait for more output
that returned at once because there was some. RunAsync never completed, so the tab
was never told and the connection was never released — a session invisible and
permanent. The loop now leaves for the drain as soon as the backlog is complete,
and RunAsync resets the credit window alongside completing it so a flusher already
parked on an acknowledgement that will never come is released.

Four tests asserted the old contract and now assert its reverse, which is the
point rather than a relaxation — WhenCreditRunsOut_ThePumpStopsReading is now
WhenCreditRunsOut_ThePumpKeepsReadingAndTheBacklogHoldsTheLine, and has to prove
both halves at once. The throughput harness gained a counting transport, because
a consumer that copies every frame into a 32 MB list was the slowest thing in the
pipeline and a harness whose consumer cannot keep up measures itself. The fake
shell gained a pace, so "a renderer that keeps up loses nothing" can be asked of a
producer a network could actually deliver rather than of one running at memory
bandwidth.

The test that would have caught this in the first place is
ARunawayRemote_KeepsBeingReadAndStaysInsideTheBacklog, and it needs the real
SSH.NET and the real sshd to say anything: a fake shell hands over bytes when it
is asked, and a real channel hands them over when they arrive. Under the old code
its BytesRead would have stopped at exactly WindowBytes.

121 terminal tests pass over three consecutive runs with no flakes, 105 against
the container, and the app, session, layout and remaining suites are unchanged and
green. Manual checks 1.10a and 1.10b cover the two symptoms a person can see: a
working set that plateaus under `yes`, and a connection that goes when the shell
does rather than when the tab does.
2026-09-04 17:16:23 +02:00
laurensandClaude Opus 5 1908189100 Make the terminal's right button copy and paste, and never open a menu
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Selecting output and right-clicking it opened the WebView's own context menu with
Copy on it, which is correct behaviour for a web page and wrong for a terminal.
What a terminal's right button has meant since the Windows console got QuickEdit,
and since PuTTY shipped, is this: with something selected it copies and drops the
selection, with nothing selected it pastes. No menu, no second click.

The gesture can only live in the page. The selection is drawn into a canvas the
host never sees, and once a terminal has focus the host's window receives no input
events at all — the same reason the Ctrl+plus chords are handled there.

◆ THE CLIPBOARD IS THE HOST'S IN BOTH DIRECTIONS, AND THE READING IS WHY.

navigator.clipboard.readText() is gated behind the clipboard-read permission in
every Chromium, and an embedded WebView with no PermissionRequested handler
answers a permission request by putting a prompt on the screen. Trading a context
menu for a permission dialog is not this change. So the page asks and the host
answers, exactly as requestFontSizeStep does.

Writing does not go the other way either, although navigator.clipboard.writeText
would have worked from the page on Windows: a clipboard that is the host's in one
direction and the page's in the other is two mechanisms to keep working across
WebView2, WebKitGTK and Android's WebView. The host has owned a clipboard delegate
since the keychain grew its COPY buttons, so each App.axaml.cs grows a
ClipboardReader beside its ClipboardWriter and MainWindowViewModel takes it.

Three opcodes: client ClipboardCopy and ClipboardPaste, server Clipboard.

◆ Clipboard IS NOT Paste, AND THE DIFFERENCE IS THE BRACKETING.

Paste carries a snippet off the sidebar, and the page deliberately *types* a
single-line one rather than bracketing it, because bash marks a bracketed paste as
an active region and a snippet should read as though it had been typed. A clipboard
paste is the case those markers are for — readline uses them to decide it has been
pasted into — so Clipboard is always bracketed and never followed by an Enter. One
opcode for both would have needed a flag meaning "which of the two kinds of paste
is this", on a payload whose existing flag byte means something else.

Both client frames are dispatched before the session lookup, which is what keeps
the gesture working in a pane whose shell has just ended: squinting at the message
a remote left behind is exactly when somebody copies the line. Dispatch was past
MA0051's length once it grew a second such branch, so the frames no pump needs to
see moved into Announce() and the font-size chord went with them.

◆ CAPTURED AND STOPPED, RATHER THAN MERELY PREVENTED.

preventDefault alone suppresses the menu and still lets xterm's own contextmenu
handler run, which moves its helper textarea under the pointer at z-index 1000 and
leaves the selection sitting in it, selected. Both of those exist to serve the
native menu. Taking the event in the capture phase on the pane and stopping it
there is what keeps the gesture wholly the page's.

rightClickSelectsWord is now false, which on macOS is a change of default rather
than a restatement of it: xterm sets it true there alone, so a right-click would
have selected the word under the pointer and copied that instead of pasting —
wrong on one platform only, which is the worst way for it to be wrong.

The renderer harness grows the pane it has been inviting since
RendererReconnectionTests: a fake Terminal, the two addons, and a real UTF-8 codec,
because both directions run through the page's own TextEncoder and TextDecoder and
a Latin-1 stub would pass a test with an em dash in the selection. Its warning
about declaring names terminal.js declares now covers the half that does not
SyntaxError — a harness frame() was silently replaced by the page's frame() and
failed six tests on a type error a long way from the cause.

Manual checks 1.11 and 11.13 are what is left for a person: that a real contextmenu
event reaches a capture listener, that no native menu is drawn once it is
prevented, and that xterm's real paste() brackets. 11.13 also records what is
unverified — whether Android's WebView delivers a pointer's secondary click as a
contextmenu event at all. ClipboardReader is wired on that head regardless,
because the alternative is a head where the paste half silently does nothing and
nobody finds out; that head is not compiled here either, this machine having no
android workload.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-25 14:46:36 +02:00
jaap-janandClaude Opus 5 c00e5dbc5c Let the terminal's text be made bigger, and remember how big
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Taking pinch-zoom off the phone left nothing in its place, and there was nothing on the desktop
either. This is the replacement, and it is deliberately not the thing that was removed: zoom scales
what has already been drawn, so the remote goes on wrapping to a width that is no longer on screen.
Changing the font size refits the grid and reports the new column count, so the far end is told it
has fewer columns. That round trip is the feature.

The size is one number, owned by the shell. It has to be, for two reasons that pull the same way: it
must survive a relaunch, and it must be reachable from a phone that has no Ctrl key to press. So the
page asks and the host decides — a signed step over a new client opcode, answered with a size over a
new server opcode. The phone's buttons and the desktop's chords arrive at the same place, and a size
set by either is the size both remember.

Stored in settings.json beside the cache rather than in it, and that is not laziness about a
migration. The cache is encrypted and unreadable until a vault is unlocked, and the first terminal of
a locked launch needs the size already. Nothing secret may go in that file; ClientSettings says so
out loud, because the next person to add a preference is the one who needs to read it.

Where it is reachable from differs per head, and only here. The phone gets A− and A+ on the
connection line — not in the accessory row, which scrolls, and a control that fixes unreadable text
must never be the thing that is off-screen. The desktop gets the three chords every terminal
emulator has, answered by the page while a terminal has focus and by the window when it does not,
plus a row in preferences that shows the current value and names the chords rather than replacing
them. Someone whose terminal is too small to read is not in a position to go looking.

Clamped 8 to 32. Below eight a monospace grid stops being legible and becomes a texture, and every
column of it is still a column the remote is being told exists; above thirty-two a phone in portrait
has too few columns to hold a prompt. The buttons disable at the ends rather than accepting presses
that do nothing, which on a terminal reads as the application having stopped responding.

The preferences screen's header comment claimed none of the design's terminal settings could be
saved, and listed the three things that were missing to make one work. All three now exist, so it
says which one is real and why the other five still are not.

Verified with the protocol suite — including that the step byte round-trips signed, since read
unsigned a step down arrives as 255 and clamps to the largest font, making "smaller" do the most
dramatic available version of "larger" — a data-plane test that the chord is heard with no session
registered, and five shell tests: the default matches the renderer's, both clamps hold, reset works,
and a size chosen in one shell is there in a second one over the same profile directory. Layout
suite and both heads build.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-02 13:15:11 +02:00
jaap-jan d07b336868 Free the terminal from the Hosts screen, and fill the room it left
The WebView sat inside the Hosts grid, so navigating to Files or the keychain
hid every open terminal and the strip that named them. A connection you had
opened was invisible from four of the five screens. The window now has two
surfaces rather than one: a nav rail that says which page you are on, and a
terminal strip that is always there and switches the whole content area to a
shell. Screen keeps meaning "which page" and never becomes a sixth kind of
page, which is why this is two properties instead of one enum with a terminal
member in it.

Every screen lives inside one wrapper panel that collapses when a terminal is
showing. That is not tidiness — the WebView hosts a Win32 child window that
composites above everything Avalonia draws, so a screen left visible over its
rectangle is a screen sliced in half, and this window has shipped that defect
once already. One decision point, IsTerminalShowing, and a nested panel rather
than five compound bindings nobody would remember to extend.

The focus choreography is the part no test in this repo can see. Every reveal
path now focuses in the same turn the WebView appeared, so all three of them
post at DispatcherPriority.Loaded and let the native control re-push its bounds
first. Going the other way had a real bug: the screen-changed branch called a
bare Focus() where it had to release the keyboard from the native child, so
switching from a terminal to Files silently ate the first keystrokes. Rare
before this commit and the primary gesture after it.

The tab strip grew a cross inside each tab, a plus that opens the quick-connect
palette, and middle-click close. Nested buttons are correct here: Avalonia
handles a left press on the cross and deliberately does not handle other
buttons, which is exactly what lets middle-click bubble up from the cross as
well as the tab. The test is PointerUpdateKind rather than
IsMiddleButtonPressed, because the latter reports button state and is also true
for a left press made while the middle button happens to be held. The handler
is on the tab and not the strip, so the background closes nothing by
construction. Plus opens the palette rather than a flyout, since a menu
dropping into the WebView's rectangle may or may not composite above a child
HWND and this repo does not make rendering claims it has not photographed.

Everything a user reads now says keychain. The wire, the database and the
cryptographic spec still say vault, deliberately: renaming those is a migration
and a protocol change for a word. That split is written down rather than left
to be rediscovered as an inconsistency.

Four things that were squeezed into the keychain's category rail, or into
nothing at all, now have screens. Pinned host keys get one, with fingerprints
never truncated and a filter that matches them, because comparing what you have
against what the operator published is the whole workflow; the approved date is
read out of the item's UUIDv7 rather than added as a column, and says so, since
it means first approval and not last use. Keys can be generated in the client,
which needed the openssh-key-v1 container written by hand — there is no BCL or
NSec helper, and the PKCS#8 route is unverified in the SSH library this uses.
The armour carries no passphrase: encrypting it needs bcrypt_pbkdf, which is
Blowfish with a swizzle, in a project whose crypto is otherwise entirely
libsodium, for a protection the key's own remarks argue is redundant inside a
vault. Generation fills the existing editor and stops, so SAVE stays the one
thing that writes. ~/.ssh/config can be imported behind a preview that is
ticked per row and writes nothing until the button; IdentityFile records the
path and imports the key material only on an explicit opt-in, because reading
somebody's private key into a vault is precisely the act this product exists to
make deliberate. Match blocks and ProxyJump are reported rather than obeyed —
one cannot be evaluated statically and the other has nothing behind it to route
with, and a preview that implied otherwise would be worse than one that admits
it.

Files can be dragged in all four directions that are honestly available. Remote
to Explorer does not ship and is not pretended to: the shell wants the bytes
during the drop, which needs a virtual file and a native COM data object,
outside what Avalonia offers. Note for the next person that Avalonia 12
replaced the drag model outright — DataObject and DataFormats are no-op stubs
and IDataObject is not in the reference assembly, so every tutorial written for
11 does not compile here.

Hosts can be grouped, flat and never nested. A parent id merged as a scalar
lets two offline clients each re-parent A under B and B under A, producing a
cycle inside an encrypted payload that no server can police and every reader
would have to detect for ever. Membership lives in that payload rather than in
the one plaintext concession ADR 0001 allows, whose test is that the relay
cannot function without it — nothing on the server reads a group, so what
plaintext would hand over is a clustering of the estate for nothing. The
plaintext column reserved for it is dropped, provably always null, and the
server now refuses a client that sends one; it was never populated, was copied
on apply, and was not cleared on delete, so a group id would have outlived the
host it described.

Snippets insert through xterm rather than through the pump, because xterm is
the only thing that knows whether the remote has bracketed paste on, and that
is what makes a shell treat embedded newlines as text instead of as execute.
The host process moves opaque bytes and never parses output, so it would have
to guess, and guessing wrong runs every line. Running is off by default and the
copy says the text goes into whatever is there — the terminal has no notion of
being at a prompt, and may be in vi or at a password prompt with echo off, so
the Enter the user presses themselves is the entire safety property.

Connections and keychain changes are recorded as synced encrypted items, which
is what makes them auditable by a team later and costs the server knowledge of
connection rate and timing from row counts alone. ADR 0001 already concedes it
cannot hide that class of metadata; the trade is now written into it rather
than left implicit. A connection entry is written once, at close, which is what
makes a synced log tractable: nothing to merge, one outbox row, no chance of
colliding with itself. Live sessions come from memory, not from the log. The
write is void by contract and posts to a bounded channel, because putting an
encrypt-and-write on the teardown path of every session is how closing the
application comes to take four seconds. A ticket opened before a lock still
closes afterwards, since a shell outlives the vault. The activity log hooks the
one generic repository every kind writes through, so it cannot miss a caller —
which is also why the log kinds themselves declare they are not audited, or the
first entry would write an entry about writing an entry. It records the names
of the fields that changed and never their values; a log with an old password
in it would be a plaintext credential store with no vault around it. Retention
is 90 days or 5,000 entries, whichever bites first, pruned on the sync loop
rather than on a second timer.

That log traffic then broke the status line, which is worth recording because
the fix is a shape and not a patch: background sync counted its own log rows as
pushed items, so the quiet rule stopped being quiet and every action's message
was overwritten a second later by a sync report. The report now separates log
rows from user items and the rule reads the latter.

S3 buckets appear as a remote in the file browser, behind the same interface an
SFTP session implements, so the queue and both panes did not have to learn what
they are talking to. Uploads go through a pipe, because the queue wants to
write and the SDK wants to read; memory is then bounded by the part size
instead of buffering a file to disk twice.

Finally, the Windows device key store moved out of the session project, which
was the one thing keeping it from being portable — everything else in it is
platform-neutral, and a Windows CNG dependency in the middle of the vault code
meant a second head could not reference it without dragging Windows along. The
seam that made the move free was already there. docs/android-port.md is the
audit behind that: what ports, what does not, in order of cost, the four
decisions taken, and an inventory of every screen and state the interface has
to carry, written so a design can be made from it directly.

dotnet build, dotnet test and dotnet format --verify-no-changes are all clean:
1240 tests at zero warnings, including the end-to-end suite against real
containers. The manual checks that headless Avalonia cannot make — the drag
from Explorer, a generated key against a real host, twelve tabs at the minimum
window width — are listed in docs/manual-checks.md and are still outstanding.
2026-07-31 20:30:05 +02:00
jaap-jan 9a76eced14 Give hosts and terminals their own screen, and the rest of the vault another
ci / build and test (ubuntu) (pull_request) Canceled after 0s
ci / build (windows) (pull_request) Canceled after 0s
Rebuilds the client's shell from an imported design: a titlebar and nav rail
it draws itself, real multi-session tabs over the one WebView, a Ctrl+K host
search, and a vault screen that merges keys, passwords and pinned host keys
into one table. Hosts left the vault column for their own screen beside the
terminal, which is what the design asks for and turned out to be the better
split anyway.

Two screens the design shows have nothing behind them yet — file transfer
and teams — and say so plainly rather than rendering invented data; every
other gap between the design and this build is recorded in
docs/design-import-gaps.md.
2026-07-31 08:39:37 +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