Clearer messages when the car's clock is wrong or a start gets stuck

A certificate the car calls not valid yet or expired, but that is fine by the
phone's clock, now says to set the car's date and time. A start that hasn't
reached the car's screen after 45 seconds says what to try, for cable and wireless.

gearslip/src/main/java/app/seb3thehacker/gearslip/GearslipRunner.kt

@@ -58,6 +58,8 @@ class GearslipRunner(
     private val parser = Frames.Parser()
     private val assembler = Frames.Assembler()
     private lateinit var identityTask: FutureTask<PhoneTls>
+    /** The certificate in use, to tell a wrong date on the car from a certificate that's really out of date. */
+    @Volatile private var phoneCert: java.security.cert.X509Certificate? = null
 
     /** Sends every message, in order, so no other thread ever blocks on the USB link. See [send]. */
     private val writer = java.util.concurrent.Executors.newSingleThreadExecutor {
@@ -130,6 +132,7 @@ class GearslipRunner(
         identityTask = FutureTask {
             val identity = identityProvider()
             val cert = identity.certificate
+            phoneCert = cert
             log.i("phone certificate source: ${identity.source}")
             SessionReport.certificate(identity.source.toString(), cert.issuerX500Principal.toString())
             log.i("  subject = ${cert.subjectX500Principal}")
@@ -407,8 +410,7 @@ class GearslipRunner(
             }
             -2, -23, -24 -> {
                 val reason = when (status) {
-                    -23 -> "The phone's certificate is not valid yet."
+                    -23, -24 -> certificateDates(status)
-                    -24 -> "The phone's certificate has expired."
                     else -> "The head unit refused the phone's certificate."
                 }
                 SessionReport.fail(SessionReport.Category.CERTIFICATE, "AuthComplete status $status", state.name, "auth $status")
@@ -449,6 +451,30 @@ class GearslipRunner(
         if (authenticationFailed) running = false
     }
 
+    /**
+     * The car checks the certificate's dates against its own clock. When they're fine by the
+     * phone's clock, the car's clock is the one that's wrong, which a flat battery or a car
+     * that never got the time from GPS leaves behind.
+     */
+    private fun certificateDates(status: Int): String {
+        val cert = phoneCert ?: return if (status == -23) "The phone's certificate is not valid yet." else "The phone's certificate has expired."
+        val now = java.util.Date()
+        val day = java.text.DateFormat.getDateInstance(java.text.DateFormat.LONG)
+        return when {
+            status == -23 && now.before(cert.notBefore) ->
+                "The phone's certificate is not valid until ${day.format(cert.notBefore)}."
+            status == -24 && now.after(cert.notAfter) ->
+                "The phone's certificate expired on ${day.format(cert.notAfter)}. Get a new one under Certificate in Settings."
+            else -> {
+                val side = if (status == -23) "behind" else "ahead"
+                log.w("the certificate's dates are fine by the phone's clock, so the car's clock is $side")
+                "The car's clock looks wrong: the certificate is valid today, but the car thinks it " +
+                    (if (status == -23) "isn't valid yet" else "has expired") +
+                    ". Set the car's date and time, then connect again."
+            }
+        }
+    }
+
     /**
      * What a real phone sends here: its icon at three sizes (fields 1 to 3), a label, its model,
      * and a session ID that's new each connection (field 6). A 2017 Hyundai on protocol 1.0
@@ -1443,6 +1469,9 @@ class GearslipRunner(
         SessionReport.print()
     }
 
+    private val startedAt = System.currentTimeMillis()
+    private var toldStuck = false
+
     private fun startWatchdog() {
         Thread {
             var lastFrames = 0
@@ -1454,6 +1483,11 @@ class GearslipRunner(
                     val idle = System.currentTimeMillis() - lastProgress
                     if (idle > 10_000) log.w("stalled in state $state for ${idle / 1000}s")
                 }
+                if (!videoStarted && !toldStuck && System.currentTimeMillis() - startedAt > STUCK_MS) {
+                    toldStuck = true
+                    log.w("still not on the car's screen after ${STUCK_MS / 1000}s, in state $state")
+                    SessionStatus.stillConnecting(if (wireless) SessionStatus.Link.WIRELESS else SessionStatus.Link.CABLE)
+                }
 
                 // Stream health. Without this a drive cannot tell "streaming fine" from
                 // "stalled after three frames" - the per-frame logging is deliberately sparse.
@@ -1546,6 +1580,9 @@ class GearslipRunner(
         /** The stats window adaptive bitrate reads, matching the watchdog's sleep. */
         const val ADAPT_WINDOW_MS = 5_000L
 
+        /** A car shows its screen within seconds; this long without one, Home says what to try. */
+        const val STUCK_MS = 45_000L
+
         // protobuf/aap_protobuf/service/control/ControlMessageType.proto:7-17
         const val MSG_VERSION_REQUEST = 1
         const val MSG_VERSION_RESPONSE = 2

gearslip/src/main/java/app/seb3thehacker/gearslip/SessionStatus.kt

@@ -14,7 +14,10 @@ object SessionStatus {
 
     enum class Phase { IDLE, CONNECTING, PROJECTING, FAILED, DISCONNECTED }
 
-    data class Snapshot(val phase: Phase, val headline: String, val detail: String)
+    /** [stuckOn] is set when connecting has gone on too long: the cable or Wi-Fi, for what to try. */
+    data class Snapshot(val phase: Phase, val headline: String, val detail: String, val stuckOn: Link? = null)
+
+    enum class Link { CABLE, WIRELESS }
 
     private val flow = MutableStateFlow(
         Snapshot(
@@ -30,6 +33,12 @@ object SessionStatus {
         flow.value = Snapshot(Phase.CONNECTING, "Connecting", stage)
     }
 
+    /** Still connecting after [GearslipRunner]'s patience ran out: Home says what to try. */
+    fun stillConnecting(link: Link) {
+        val now = flow.value
+        if (now.phase == Phase.CONNECTING) flow.value = now.copy(stuckOn = link)
+    }
+
     fun projecting() {
         flow.value = Snapshot(Phase.PROJECTING, "Projecting", "Streaming to the head unit.")
     }

gearslip/src/main/java/app/seb3thehacker/gearslip/ui/HomeScreen.kt

@@ -307,6 +307,11 @@ private fun StatusCard(status: SessionStatus.Snapshot) {
                     )
                     SessionStatus.Phase.PROJECTING -> stringResource(R.string.status_projecting_detail)
                     SessionStatus.Phase.DISCONNECTED -> stringResource(R.string.status_disconnected_detail)
+                    SessionStatus.Phase.CONNECTING -> when (status.stuckOn) {
+                        SessionStatus.Link.CABLE -> stringResource(R.string.status_stuck_cable)
+                        SessionStatus.Link.WIRELESS -> stringResource(R.string.status_stuck_wireless)
+                        null -> status.detail
+                    }
                     else -> status.detail
                 }
                 Text(headline, style = MaterialTheme.typography.headlineSmall, fontWeight = FontWeight.SemiBold)

gearslip/src/main/res/values/strings.xml

@@ -862,6 +862,8 @@
     <string name="status_idle_detail">Plug into the car\'s USB port, or connect wirelessly. Gearslip opens by itself when the car answers.</string>
     <string name="status_no_car">The phone is charging, but no car has answered. Some cables only charge; try one that carries data.</string>
     <string name="status_no_car_graphene">The phone is charging, but no car has answered. Check that USB-C port control, under Security &amp; privacy, allows data and isn\'t set to Charging-only.</string>
+    <string name="status_stuck_cable">The car hasn\'t shown Gearslip yet. Unplug the cable, wait a few seconds, and plug it back in. If it keeps happening, try another cable or USB port, and share the log in an issue.</string>
+    <string name="status_stuck_wireless">The car hasn\'t shown Gearslip yet. Turn the car off and on again, or connect with a cable. If it keeps happening, share the log in an issue.</string>
     <string name="status_open_settings">Open settings</string>
     <string name="status_connecting">Connecting</string>
     <string name="status_projecting">Projecting</string>