[client] Android - Create the Android fake IP manager lazily on DNS flag enable - #6989
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pappz wants to merge 1 commit into
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[client] Android - Create the Android fake IP manager lazily on DNS flag enable#6989pappz wants to merge 1 commit into
pappz wants to merge 1 commit into
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The fake IP manager was only created at route manager construction, from the DNS feature flag fetched by the initial GetNetworkMap call. When the flag flipped to true mid-session, UpdateRoutes set useNewDNSRoute but never created the manager, so domain routes added after the flip got a DNS interceptor with a nil fake IP manager. internalDnatFw only checked for a firewall and GOOS, so the interceptor took the DNAT path and called GetFakeIP/AllocateFakeIP on the nil *fakeip.Manager. These methods lock m.mu first, which is a nil pointer dereference: the first DNS answer for such a route panicked and crashed the VPN service. The fake IP blocks (240.0.0.0/8 and its v6 pair) also never reached the TUN, since only the constructor registered them. Create the manager and its TUN routes from UpdateRoutes when the flag turns on, notify so the fake IP blocks get into the TUN without a client route change, and treat a nil manager as no internal DNAT. This is groundwork for removing the initial GetNetworkMap fetch, after which every startup goes through the flag-off-to-on transition.
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📝 WalkthroughWalkthroughAndroid fake-IP route creation is now conditional and reusable during setup and runtime route updates. The Android notifier emits a network-change notification when fake routes are assigned, and internal DNAT requires an initialized fake-IP manager. ChangesAndroid fake-IP route lifecycle
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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 `@client/internal/routemanager/manager.go`:
- Around line 472-474: Publish fake-IP route changes only after the complete
route state is committed: in client/internal/routemanager/manager.go:472-474
defer notification until the normal route update has committed currentRoutes;
initialize the notifier route state before its first notification at
manager.go:168-171; separate fake-route assignment from notification at
manager.go:194-195; and in
client/internal/routemanager/notifier/notifier_android.go:42-44 serialize or
coalesce callbacks so notifications occur only with a complete, ordered
snapshot.
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📒 Files selected for processing (3)
client/internal/routemanager/dnsinterceptor/handler.goclient/internal/routemanager/manager.goclient/internal/routemanager/notifier/notifier_android.go
Comment on lines
+472
to
+474
| if runtime.GOOS == "android" && useNewDNSRoute && m.fakeIPManager == nil { | ||
| m.enableFakeIPRoutes() | ||
| } |
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🗄️ Data Integrity & Integration | 🟠 Major | 🏗️ Heavy lift
Publish fake-IP route changes only after the complete route state is committed.
The current flow emits an intermediate snapshot before initial/current routes are installed, and asynchronous callbacks can arrive out of order, potentially leaving the TUN with stale or missing routes.
client/internal/routemanager/manager.go#L472-L474: defer notification until the normal route update has committedcurrentRoutes.client/internal/routemanager/manager.go#L168-L171: initialize the notifier’s route state before the first notification.client/internal/routemanager/manager.go#L194-L195: separate fake-route assignment from notification.client/internal/routemanager/notifier/notifier_android.go#L42-L44: serialize or coalesce callbacks, or notify only after the full snapshot is ready.
📍 Affects 2 files
client/internal/routemanager/manager.go#L472-L474(this comment)client/internal/routemanager/manager.go#L168-L171client/internal/routemanager/manager.go#L194-L195client/internal/routemanager/notifier/notifier_android.go#L42-L44
🤖 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 `@client/internal/routemanager/manager.go` around lines 472 - 474, Publish
fake-IP route changes only after the complete route state is committed: in
client/internal/routemanager/manager.go:472-474 defer notification until the
normal route update has committed currentRoutes; initialize the notifier route
state before its first notification at manager.go:168-171; separate fake-route
assignment from notification at manager.go:194-195; and in
client/internal/routemanager/notifier/notifier_android.go:42-44 serialize or
coalesce callbacks so notifications occur only with a complete, ordered
snapshot.
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lixmal
approved these changes
Jul 31, 2026
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Describe your changes
The fake IP manager was only created at route manager construction, from the DNS feature flag fetched by the initial GetNetworkMap call. When the flag flipped to true mid-session, UpdateRoutes set useNewDNSRoute but never created the manager, so domain routes added after the flip got a DNS interceptor with a nil fake IP manager.
internalDnatFw only checked for a firewall and GOOS, so the interceptor took the DNAT path and called GetFakeIP/AllocateFakeIP on the nil *fakeip.Manager. These methods lock m.mu first, which is a nil pointer dereference: the first DNS answer for such a route panicked and crashed the VPN service. The fake IP blocks (240.0.0.0/8 and its v6 pair) also never reached the TUN, since only the constructor registered them.
Create the manager and its TUN routes from UpdateRoutes when the flag turns on, notify so the fake IP blocks get into the TUN without a client route change, and treat a nil manager as no internal DNAT.
This is groundwork for removing the initial GetNetworkMap fetch, after which every startup goes through the flag-off-to-on transition.
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