fix(hook): observe every network connection at the socket driver by donislawdev · Pull Request #47 · donislawdev/ChronoMock

donislawdev · 2026-09-23T14:31:46Z

What was wrong

The audit is meant to raise source.network_at_start when an application opens a network connection, because it may then take the time from a server that no local substitution reaches. The README promises it ("connect observed, warned"). The observer was a detour on ws2_32's connect export, and two of the three ways to connect never call it:

WSAConnect goes straight to the provider.
ConnectEx is an extension function obtained through WSAIoctl, not an export. WSAConnectByName, WSAConnectByList, WinHTTP and WinINet all connect through it, and so do the .NET, Node.js and Go runtimes.

Measured under a real session, 8 of 13 runtime connection paths were counted as zero, with no caution and a works verdict: WinHTTP, .NET (HttpClient, Socket.Connect, ConnectAsync), Node.js (http, net) and Go (net/http, net.Dial). Only Python and Java were seen.

The fix

Every Winsock connection attempt reaches the socket driver through ntdll!NtDeviceIoControlFile with one of two control codes: 0x12007 for connect and WSAConnect, and 0x120C7 for ConnectEx. Measured on x64 and x86 across eleven paths (blocking, non-blocking, UDP and IPv6 connect, WSAConnect, ConnectEx, WSAConnectByName, WSAConnectByList, WinHTTP, WinINet), each attempt sends exactly one of them and never both. A datagram sent without a connection sends neither. The codes are not documented by Microsoft, and reverse engineering of the driver names their handlers AfdConnect and AfdSuperConnect.

The detour reads the control code, a plain number, and nothing else. It never dereferences an argument, so no undocumented driver structure is parsed. It counts a connection and forwards the call untouched.
Cost: 200 000 socket polls through the same function, five alternating pairs per bitness. x64 differed by -40 ns against a run-to-run spread of about 100 ns, x86 by +5 ns on about 1 170 ns.
The channel keeps its name, connect, because it is a contract key. ChannelDef::export() now names the symbol the hook detours, so the name on the wire and the export can differ for this one channel. Without it, make_hook would look for connect in ntdll and the channel would quietly land in unobserved.
The detour on ws2_32's connect is removed. Keeping it would count every connect twice. The channel also leaves the late-install path, because ntdll is present from the start, so a session without --scale-duration no longer has any late channel to look for.
wait.network_timeouts_scaled now fires when the process opened a connection, rather than when ws2_32 is loaded. The observer is installed in every process now, so its install bit no longer says anything about the network stack, and a counted connection is the narrower signal. This also resolves the open review point from fix(hook): detour the duration axis and the waits where their code lives #46 about inferring ws2_32's presence from a hook that may have failed. The first sentence of the caution changes to match, in the CLI text and in both languages.

After the change, the same 13 runtime paths are all counted, each exactly once (Java's HttpClient counts 2, as it did before the change), and each raises the caution.

Guards, each checked by reverting the fix

crates/cli/tests/network_observer.rs (CI). This test binary connects under a session through connect, WSAConnect and ConnectEx to a loopback listener. It expects exactly three connections, plus the caution, after a control run without a session. With the old observer (hook and ctl reverted) it counted Some(1). With the funnel but without the ConnectEx code, Some(2). It is registered in network.rs for spawn, socket and winsock, each with its reason.
Unit tests:
- is_connection_attempt on the measured codes and their neighbours: bind, datagram, poll, and a name-resolution code in the ordinary CTL_CODE layout.
- ChannelDef::export.
- The rewritten warning rule in mech.
A local harness scenario on both bitnesses. It covers four paths, WinHTTP included, and expects exactly four, so a server-side accept cannot be counted either. It also checks that the timeouts caution appears only under --scale-duration. The old observer failed it with connect=1,1.

Changed ratchet, stated rather than buried

The frozen count of too_many_arguments allows in tests/shape.rs goes from 4 to 5. The new detour mirrors NtDeviceIoControlFile's ten parameters, the same class as the three process-creation detours already counted there. On 32-bit the callee pops them, so the list cannot be shorter.

Not covered, and said so

A datagram sent without a connection. It is not one, and counting datagrams would count every packet of a game. The README now says this.
A Winsock provider other than the system's own, and direct system calls that skip ntdll.

Checks

The full tools/gates.ps1 -Env run was 14/15, red only on the shape ratchet above: test-cs 627, harness 199/199 on x64 and on x86, lint 65 files. After the ratchet change only the red gate was rerun, together with both clippy gates, and all three passed: test-rust 527 (524 + 3). clippy --all-targets -D warnings is clean on every touched crate. The wire, Cov, CTL_LAYOUT_VERSION (6) and CHANNEL_COUNT (41) are unchanged.

🤖 Generated with Claude Code

Summary by CodeRabbit

Bug Fixes
- Network connection detection now tracks connection attempts more accurately across supported networking APIs, including .NET, Node.js, Go, Java, and Python. Unconnected datagrams are not counted.
- Timeout warnings now appear when a connection is observed while sped-up timers are active, rather than when the network stack is merely loaded.

The audit warns source.network_at_start when an application opens a network connection, because it may then take the time from a server. The observer sat on ws2_32's connect export, and two of the three ways to connect never call it: WSAConnect, and ConnectEx, which WSAConnectByName, WSAConnectByList, WinHTTP and WinINet use and which the .NET, Node.js and Go runtimes connect through. Measured under a real session, 8 of 13 runtime connection paths were counted as zero, with no caution and a clean verdict. Every Winsock connection attempt reaches the socket driver through ntdll!NtDeviceIoControlFile with one of two control codes, 0x12007 for connect and WSAConnect and 0x120C7 for ConnectEx. Measured on both bitnesses across eleven paths, each attempt sends exactly one of them, and a datagram sent without a connection sends neither. The detour reads the control code and nothing else, counts a connection and forwards the call untouched. Its cost stayed inside the run-to-run noise against 200 000 socket polls. The channel keeps its name, connect, which is a contract key. ChannelDef::export now names the symbol the hook detours, so the name on the wire and the export can differ for this one channel. The old detour on ws2_32 is gone, since keeping it would count every connect twice, and the channel leaves the late-install path because ntdll is present from the start. wait.network_timeouts_scaled now fires when the process opened a connection rather than when ws2_32 is loaded. The observer is installed in every process now, so its install bit no longer says anything about the network stack, and a counted connection is the narrower and truer signal. The frozen count of too_many_arguments allows in tests/shape.rs goes from four to five. The new detour mirrors NtDeviceIoControlFile's ten parameters, the same class as the three process-creation detours already counted there, and on 32-bit the callee pops them, so the list cannot be made shorter. Guards, each checked by reverting the fix: a CI test that connects through connect, WSAConnect and ConnectEx under a session and expects exactly three (the old observer counted one, dropping the ConnectEx code gave two), and unit tests for the control codes, ChannelDef::export and the warning rule. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

coderabbitai · 2026-09-23T14:32:00Z

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📝 Walkthrough

Walkthrough

The connection observer moves from Winsock’s connect export to NtDeviceIoControlFile in ntdll. The observer counts specified connection attempts. Network-timeout warnings now depend on an observed connection and installed tick-count channels.

Changes

Network connection observation

Layer / File(s)	Summary
Channel mapping and hook routing `crates/ctl/src/lib.rs`, `crates/hook/src/lib.rs`	The connection channel keeps the report name `connect` and maps to `NtDeviceIoControlFile` in `ntdll`. Hook resolution uses channel export names, and `connect` is removed from the late Winsock channel.
Native connection observer and validation `crates/hook/src/lib.rs`, `crates/cli/tests/network_observer.rs`, `crates/cli/tests/network.rs`, `crates/cli/tests/shape.rs`, `crates/cli/tests/hygiene.rs`, `gui/ChronoMock.Protocol.Tests/BinaryImportsTests.cs`	The hook counts two specified device-control codes and forwards calls through `NtDeviceIoControlFile`. A Windows integration test checks connections through `TcpStream`, `WSAConnect`, and `ConnectEx`. Related test permissions and shape checks are updated.
Connection-based timeout warning `crates/mech/src/lib.rs`, `crates/cli/src/report.rs`, `gui/ChronoMock.App/Localization/Strings.*.json`, `README.md`, `CHANGELOG.md`	The warning requires duration scaling, an observed connection, and at least one tick-count channel. Tests, warning text, and network-support documentation reflect the connection-based condition.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Sequence Diagram(s)

sequenceDiagram
  participant TargetProcess
  participant h_ntdiocf
  participant NtDeviceIoControlFile
  participant gather_coverage
  TargetProcess->>h_ntdiocf: Call NtDeviceIoControlFile
  h_ntdiocf->>h_ntdiocf: Count recognized connection control codes
  h_ntdiocf->>NtDeviceIoControlFile: Forward call arguments
  h_ntdiocf->>gather_coverage: Pass observed connection state
  gather_coverage->>TargetProcess: Include network-timeout warning when conditions match

Suggested labels: bug, security, performance, ui

Merge Risk: 🔵 Low · up to 9b572

Connection auditing now happens at the system socket driver, and the timeout warning fires only after a real connection. The change is mergeable with a small documentation fix. The support matrix should not promise that every connection is observed, because traffic through non-system Winsock providers is not seen.

🚥 Pre-merge checks | ✅ 11 | ❌ 3

❌ Failed checks (3 warnings)

Check name	Status	Explanation	Resolution
System Changes Are Reversible	⚠️ Warning	The PR changes process-hooking state. It moves the connection detour to `ntdll!NtDeviceIoControlFile` (`ChannelDef::module` changes to `Ntdll`, `export()` returns `NtDeviceIoControlFile`, and `install…	Add lifecycle cleanup for every injected process. Save the original detoured bytes and module state before enabling each hook, then disable and remove every MinHook detour, restore the original bytes, unmap session state, and unload the inj…
Clear User-Facing Text	⚠️ Warning	The PR changes user-facing warnings but leaves inconsistent terminology. In the CLI `warnings:` list, `wait.network_timeouts_scaled` says “this application opened a network connection”, while `source.…	Use one subject and one event term in all warning, README, changelog, and localization text. For example: “This application attempted to open a network connection. It may read the time from a server, which no local clock can change.” Use th…
No Resource Leaks	⚠️ Warning	The new Windows probe has two resource-lifecycle gaps in `crates/cli/tests/network_observer.rs`. `probe_connects_three_ways` calls `WSAStartup` at line 188 but never calls `WSACleanup`; the Winsock st…	Use RAII cleanup. Add a Winsock guard that calls `WSACleanup` when `WSAStartup` succeeds, including paths that fail while writing output or asserting results. Use `tempfile::TempDir` or a local `Drop` guard for the scratch directory so its …

✅ Passed checks (11 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: moving network-connection observation to the socket driver. It is specific, user- and code-relevant, and 64 characters long.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Tests For Changed Behavior	✅ Passed	The PR changes runtime connection observation and warning behavior, and it adds or updates tests for that behavior. `crates/cli/tests/network_observer.rs` adds a non-ignored integration test that exer…
No Secrets Or Debug Leftovers	✅ Passed	No prohibited files or content were added. The authoritative diff changes 13 existing paths and adds only `crates/cli/tests/network_observer.rs`; it adds no `CLAUDE.md`, `CLAUDE.local.md`, `AGENTS.md`…
No Hardcoded Ui Styling	✅ Passed	The pull request does not change GUI code or control styling. It only changes two localization strings and a C# binary-import test; no XAML, Slint, Fyne, Tkinter, or WPF code-behind is modified.
No Obvious Performance Problems	✅ Passed	No explicit performance failure condition is introduced. The new `NtDeviceIoControlFile` detour performs two comparisons and increments the counter only for the two connection codes, then forwards the…
Desktop Robustness	✅ Passed	The changed production code only observes target connections at `ntdll!NtDeviceIoControlFile` and forwards them. It does not initiate network calls, add settings or asset loading, change culture-sensi…
Safe File Parsing	✅ Passed	No unsafe file parsing was introduced. The new test parses only session JSON lines with `serde_json::from_str::<serde_json::Value>` and skips malformed lines. It writes and reads two controlled `.txt`…
Scope, Duplication And Docs	✅ Passed	PASS: The reviewed diff is scoped to the titled network-observer fix. It moves the connection hook to `NtDeviceIoControlFile`, updates the existing `ChannelDef` resolution path, changes the related ti…

Full details: System Changes Are Reversible

Explanation

The PR changes process-hooking state. It moves the connection detour to ntdll!NtDeviceIoControlFile (ChannelDef::module changes to Ntdll, export() returns NtDeviceIoControlFile, and install() creates h_ntdiocf). The hook is enabled with MinHook and injected into the target process. The stop path does not restore the original process state: Session::Drop only unmaps the control view and closes handles, while the code states that the target keeps its hooks after detach and calls full residue cleanup a later slice. No hook disable/remove or DLL-unload path exists. Therefore the new detour remains installed after session stop or core failure, and there is no restoration path for stop, crash, or next start. The visible stop action only ends the core or terminates the target; it does not restore hooks in a surviving target.

Resolution

Add lifecycle cleanup for every injected process. Save the original detoured bytes and module state before enabling each hook, then disable and remove every MinHook detour, restore the original bytes, unmap session state, and unload the injected DLL when the session stops. Run this cleanup on normal stop, application close, core crash, and startup recovery before a new session reuses the control state. Keep cleanup scoped to processes selected for the session and expose the cleanup result through the existing stop/recovery UI.

Full details: Clear User-Facing Text

Explanation

The PR changes user-facing warnings but leaves inconsistent terminology. In the CLI warnings: list, wait.network_timeouts_scaled says “this application opened a network connection”, while source.network_at_start says “the target opened a network connection” for the same process. The README and the changed hook identify the event as a “connection attempt”; the hook increments the count before forwarding NtDeviceIoControlFile, so the text also implies a successful connection when the implementation counts an attempt. The GUI strings consistently use “application”, but they retain the same success-oriented wording.

Resolution

Use one subject and one event term in all warning, README, changelog, and localization text. For example: “This application attempted to open a network connection. It may read the time from a server, which no local clock can change.” Use the equivalent lower-case CLI text and Polish translation, and replace the CLI source warning’s “the target opened” with “this application attempted to open”.

Full details: No Resource Leaks

Explanation

The new Windows probe has two resource-lifecycle gaps in crates/cli/tests/network_observer.rs. probe_connects_three_ways calls WSAStartup at line 188 but never calls WSACleanup; the Winsock startup reference remains active until the child process exits. every_way_to_connect_reaches_the_connection_observer creates a scratch directory at lines 249-251 and removes it only at line 287, so any failed assertion or later error leaves control.txt, session.txt, and the directory in the system temporary folder. The socket and event handles do have normal-path closes.

Resolution

Use RAII cleanup. Add a Winsock guard that calls WSACleanup when WSAStartup succeeds, including paths that fail while writing output or asserting results. Use tempfile::TempDir or a local Drop guard for the scratch directory so its files and directory are removed during unwinding as well as on success. Preserve the existing closesocket and CloseHandle cleanup for the native socket and event handles.

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Inline comments:
In `@crates/hook/src/lib.rs`:
- Line 1783: Replace the repeated status-code literal in the None branch with
the existing STATUS_UNSUCCESSFUL constant, matching its use in h_ntqsi,
h_ntdelay, and h_ntcup.

In `@README.md`:
- Line 361: Update the README network-coverage row to limit its claim to
connection attempts reaching the system AFD provider through
ntdll!NtDeviceIoControlFile, identify the listed runtime paths as covered, and
state that non-system Winsock providers are outside coverage. Preserve the
existing datagram distinction; do not add documentation about direct system
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📒 Files selected for processing (13)

CHANGELOG.md
README.md
crates/cli/src/report.rs
crates/cli/tests/hygiene.rs
crates/cli/tests/network.rs
crates/cli/tests/network_observer.rs
crates/cli/tests/shape.rs
crates/ctl/src/lib.rs
crates/hook/src/lib.rs
crates/mech/src/lib.rs
gui/ChronoMock.App/Localization/Strings.en.json
gui/ChronoMock.App/Localization/Strings.pl.json
gui/ChronoMock.Protocol.Tests/BinaryImportsTests.cs

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