Add peer-share toggle to lantern-core (Share My Connection PR 3/4)

[myleshorton]

PR 3 of 4 implementing the lantern-side wiring for Share My Connection (peer-proxy). Builds on radiance #458 (peer module) and #460 (LocalBackend wiring).

Blocked on radiance #460 merging. This PR temporarily bumps radiance to the tip of fisk/peer-localbackend so the new settings.PeerShareEnabledKey is available. Re-pin to a release tag after radiance #460 merges.

Lifecycle

```
Dart toggle → setPeerProxyEnabled(C.int)
→ LanternCore.SetPeerShareEnabled(bool)
→ ipc.Client.PatchSettings({PeerShareEnabledKey: ...})
→ radiance LocalBackend.PatchSettings dispatch
→ peer.Client.Start / Stop
```

What's in here

• lantern-core/core.go — new PeerShare interface (mirrors Ads / SmartRouting), embedded in Core. SetPeerShareEnabled patches via the radiance IPC client; IsPeerShareEnabled reads the snapshot.
• lantern-core/ffi/ffi.go — //export setPeerProxyEnabled and //export isPeerProxyEnabled, mirroring setBlockAdsEnabled / isBlockAdsEnabled exactly.
• lantern-core/mobile/mobile.go — gomobile-bind surface (SetPeerShareEnabled / IsPeerShareEnabled) so Android can toggle once Dart wires it up.
• go.mod / go.sum — provisional radiance bump to 6a238ce (fisk/peer-localbackend tip).

Naming

C export name uses PeerProxy to match the existing user-facing terminology in this repo (the toggle stub in lib/features/setting/vpn_setting.dart was drafted as "Peer Proxy"). Internal Go names use PeerShare to match the radiance setting key (PeerShareEnabledKey). The Dart side will route setPeerProxyEnabled in PR 4.

What's NOT in here (PR 4)

• ffigen regen for the auto-generated Dart bindings.
• LanternFFIService.setPeerProxyEnabled Dart method.
• app_setting_notifier.setPeerProxy() body rewrite (mirror setBlockAds rollback pattern).
• Optional status indicator wired to the new SSE (/peer/status/events from radiance Write a complete spec of Lantern in preparation for a security audit #460).

Test plan

• go build ./lantern-core/...
• go test ./lantern-core/...
• golangci-lint run --new-from-rev=origin/main ./lantern-core/...
• End-to-end manual deferred until PR 4 (when the Dart toggle lands).

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Added peer sharing controls, allowing users to enable or disable peer proxy sharing.
  • Added support for checking the current peer sharing status across core, FFI, and mobile interfaces.
  • Peer sharing settings remain accessible even when the core service is temporarily unavailable.

• Chores

  • Updated supporting dependencies to newer versions.

[Copilot]

Pull request overview

Adds Lantern-side wiring for the Share My Connection feature by introducing a new peer-share toggle in lantern-core, exposed through both gomobile bindings and the existing C FFI surface, and backed by a radiance settings patch.

Changes:

• Add a PeerShare interface to lantern-core and implement SetPeerShareEnabled / IsPeerShareEnabled via radiance settings (PatchSettings + snapshot read).
• Expose the toggle through FFI exports (setPeerProxyEnabled / isPeerProxyEnabled) and gomobile (SetPeerShareEnabled / IsPeerShareEnabled).
• Temporarily bump github.com/getlantern/radiance to a newer pseudo-version containing settings.PeerShareEnabledKey.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
lantern-core/mobile/mobile.go	Adds gomobile-facing setters/getters to toggle peer-share and query its current state.
lantern-core/ffi/ffi.go	Adds C-exported functions to toggle/query peer-share from the Dart/FFI layer.
lantern-core/core.go	Introduces PeerShare interface and core implementation backed by radiance settings.
go.mod	Updates the radiance dependency to a newer pseudo-version for the new settings key.
go.sum	Updates sums to match the radiance version bump.

---

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[teamlantern]

This PR has been inactive for 30 days.

Waiting on: none

It will be closed automatically in 7 days if no action is taken.

[teamlantern]

This PR has been inactive for 30 days.

Waiting on: none

It will be closed automatically in 7 days if no action is taken.

[coderabbitai]

📝 Walkthrough

Walkthrough

The core API now supports enabling and reading peer-sharing state. FFI and mobile bindings expose the feature. The dependency versions for radiance and lantern-box also change.

Changes

Peer sharing controls

Layer / File(s)	Summary
Core peer-sharing API lantern-core/core.go, go.mod	The Core interface includes peer-sharing methods. LanternCore reads and updates the setting through IPC-backed settings. Dependency versions are updated.
FFI peer-sharing endpoints lantern-core/ffi/ffi.go	FFI functions set peer sharing and return its state as 1 or 0.
Mobile peer-sharing bindings lantern-core/mobile/mobile.go	Mobile methods forward peer-sharing updates and return false when the core is unavailable or the lookup fails.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant MobileOrFFI
  participant LanternCore
  participant IPCSettings
  MobileOrFFI->>LanternCore: SetPeerShareEnabled(enabled)
  LanternCore->>IPCSettings: Patch peer-sharing setting
  MobileOrFFI->>LanternCore: IsPeerShareEnabled()
  LanternCore->>IPCSettings: Read peer-sharing setting
  IPCSettings-->>LanternCore: Return setting value
  LanternCore-->>MobileOrFFI: Return enabled state

Loading

Possibly related PRs

• getlantern/lantern#8883: Updates the same radiance and lantern-box dependencies.
• getlantern/lantern#8894: Updates the github.com/getlantern/radiance dependency.
• getlantern/lantern#8924: Updates the github.com/getlantern/radiance dependency.

Suggested reviewers: copilot, atavism, garmr-ulfr, jigar-f

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the peer-share toggle added to lantern-core and matches the main purpose of the changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fisk/peer-ffi

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated no new comments.

Suppressed comments (2)

lantern-core/mobile/mobile.go:222

• Function grouping/order looks inconsistent here: SetSmartRoutingEnabled is separated from IsSmartRoutingEnabled by the new PeerShare functions, whereas the surrounding toggles keep Set/Is pairs adjacent (e.g., BlockAds). Consider regrouping so each feature’s Set/Is functions remain together for easier scanning and future edits.

func SetSmartRoutingEnabled(enabled bool) error {
	slog.Info("smart-routing: SetSmartRoutingEnabled", "enabled", enabled)
	return withCore(func(c lanterncore.Core) error {
		return c.SetSmartRoutingEnabled(enabled)
	})
}

func SetPeerShareEnabled(enabled bool) error {
	slog.Info("peer-share: SetPeerShareEnabled", "enabled", enabled)
	return withCore(func(c lanterncore.Core) error {
		return c.SetPeerShareEnabled(enabled)
	})
}

func IsPeerShareEnabled() bool {
	ok, err := withCoreR(func(c lanterncore.Core) (bool, error) {
		return c.IsPeerShareEnabled(), nil
	})
	if err != nil {
		return false
	}
	return ok
}

go.mod:31

• The PR description says the temporary radiance bump is to commit 6a238ce, but go.mod is pinned to pseudo-version v0.0.0-20260805211630-2d796b8547f6 (commit 2d796b8547f6). Please reconcile this so reviewers and future pinning work are based on the intended radiance revision (either update the description or pin to the intended commit/tag).

require (
	github.com/alecthomas/assert/v2 v2.3.0
	github.com/getlantern/lantern-server-provisioner v0.0.0-20251031121934-8ea031fccfa9
	github.com/getlantern/radiance v0.0.0-20260805211630-2d796b8547f6
	github.com/sagernet/sing-box v1.12.22
	golang.org/x/mobile v0.0.0-20250711185624-d5bb5ecc55c0
	golang.org/x/sys v0.45.0

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@lantern-core/ffi/ffi.go`:
- Around line 1425-1426: Update the isPeerProxyEnabled getter around requireCore
so the unavailable-core path does not leak the allocated C error string: either
call lanternCore.Load() directly or capture and free the error pointer before
returning 0, while preserving the existing IsPeerShareEnabled check for an
available core.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 9e8cec18-a90e-43c4-b7a9-5911a739612f

📥 Commits

Reviewing files that changed from the base of the PR and between 8a9af4a and 72b2c69.

⛔ Files ignored due to path filters (1)

• go.sum is excluded by !**/*.sum

📒 Files selected for processing (4)

• go.mod
• lantern-core/core.go
• lantern-core/ffi/ffi.go
• lantern-core/mobile/mobile.go

[coderabbitai]

🩺 Stability & Availability | 🟠 Major | ⚡ Quick win

Release the error string allocated on the unavailable-core path.

When the core is unavailable, requireCore allocates a C.CString at Line 61. Line 1425 discards the returned pointer. Repeated calls to isPeerProxyEnabled before initialization can therefore grow the native heap without bound.

Read lanternCore.Load() directly for this getter, or free the error string before returning 0.

🐛 Proposed fix

 func isPeerProxyEnabled() C.int {
-	c, _ := requireCore()
-	if c != nil && c.IsPeerShareEnabled() {
+	c := lanternCore.Load()
+	if c != nil && (*c).IsPeerShareEnabled() {
 		return 1
 	}
 	return 0
 }

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

	c, _ := requireCore()
	if c != nil && c.IsPeerShareEnabled() {
	c := lanternCore.Load()
	if c != nil && (*c).IsPeerShareEnabled() {
	return 1
	}
	return 0
	}

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lantern-core/ffi/ffi.go` around lines 1425 - 1426, Update the
isPeerProxyEnabled getter around requireCore so the unavailable-core path does
not leak the allocated C error string: either call lanternCore.Load() directly
or capture and free the error pointer before returning 0, while preserving the
existing IsPeerShareEnabled check for an available core.