fix LIVI not connecting

The head unit speaks first and gave up while the phone spent a second unlocking its
certificate before reading. Read straight away and unlock the certificate alongside it,
and keep it unlocked between connections.

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

@@ -47,7 +47,10 @@ object CertProvider {
         val kind: Kind = Kind.SELF_SIGNED,
     )
 
-    /** Loaded fresh each call, so a newly imported or pushed cert takes effect on the next connect. */
+    /**
+     * The identity for the next connection. A newly imported or pushed cert takes effect on the
+     * next connect: see [loadFromFiles] for how the cache notices.
+     */
     fun load(context: Context): Identity = loadFromFiles(context) ?: run {
         val generated = SelfSignedCert.generate()
         Identity(
@@ -65,7 +68,38 @@ object CertProvider {
      */
     fun loadSupplied(context: Context): Identity? = loadFromFiles(context)
 
+    /**
+     * Unlocking a PKCS#12 file takes about a second on a Pixel 6, which a head unit waiting for
+     * its first reply may not wait out. So the unlocked identity is kept, keyed on the files it
+     * could come from: importing, downloading, removing or pushing a cert changes the key.
+     */
+    @Volatile private var cached: Pair<String, Identity>? = null
+
+    private fun sourcesKey(context: Context): String {
+        val dir = context.getExternalFilesDir(null)
+        val files = listOf(
+            importedFile(context, P12_NAME),
+            downloadedFile(context, P12_NAME),
+            dir?.let { File(it, P12_NAME) },
+            dir?.let { File(it, PASS_NAME) },
+        )
+        return files.joinToString("|") { f -> f?.let { "${it.path}:${it.lastModified()}:${it.length()}" } ?: "-" }
+    }
+
+    /** Unlocks the certificate ahead of time, so the first connection doesn't wait on it. */
+    fun warm(context: Context) {
+        runCatching { loadFromFiles(context) }
+    }
+
     private fun loadFromFiles(context: Context): Identity? {
+        val key = sourcesKey(context)
+        cached?.let { (k, identity) -> if (k == key) return identity }
+        val identity = unlockFromFiles(context) ?: return null
+        cached = key to identity
+        return identity
+    }
+
+    private fun unlockFromFiles(context: Context): Identity? {
         val imported = importedFile(context, P12_NAME)
         if (imported.isFile) {
             runCatching {

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

@@ -10,6 +10,7 @@ import app.seb3thehacker.gearslip.car.CarServices
 import app.seb3thehacker.gearslip.car.CarSettings
 import java.io.InputStream
 import java.io.OutputStream
+import java.util.concurrent.FutureTask
 
 /**
  * Drives the phone side of the control-channel handshake far enough to answer one question:
@@ -38,7 +39,10 @@ class GearslipRunner(
 
     private val parser = Frames.Parser()
     private val assembler = Frames.Assembler()
-    private lateinit var tls: PhoneTls
+    private lateinit var identityTask: FutureTask<PhoneTls>
+
+    /** Waits for the certificate only when TLS is first needed; see [run]. */
+    private val tls: PhoneTls by lazy { identityTask.get() }
 
     @Volatile private var state = State.WAIT_VERSION
     @Volatile private var lastProgress = System.currentTimeMillis()
@@ -76,14 +80,19 @@ class GearslipRunner(
         SessionStatus.connecting("Connected to the head unit")
         log.i("device=${Build.MANUFACTURER} ${Build.MODEL}  android=${Build.VERSION.RELEASE} (sdk ${Build.VERSION.SDK_INT})")
 
-        val identity = identityProvider()
+        // The head unit speaks first, and some give up if the phone doesn't read within about a
-        val cert = identity.certificate
+        // second. The version exchange needs no certificate, so read at once and unlock the
-        log.i("phone certificate source: ${identity.source}")
+        // certificate alongside; the TLS handshake waits for it.
-        SessionReport.certificate(identity.source.toString(), cert.issuerX500Principal.toString())
+        identityTask = FutureTask {
-        log.i("  subject = ${cert.subjectX500Principal}")
+            val identity = identityProvider()
-        log.i("  issuer  = ${cert.issuerX500Principal}")
+            val cert = identity.certificate
-        log.i("  serial  = ${cert.serialNumber}  valid ${cert.notBefore}..${cert.notAfter}")
+            log.i("phone certificate source: ${identity.source}")
-        tls = PhoneTls(identity.keyStore, identity.password)
+            SessionReport.certificate(identity.source.toString(), cert.issuerX500Principal.toString())
+            log.i("  subject = ${cert.subjectX500Principal}")
+            log.i("  issuer  = ${cert.issuerX500Principal}")
+            log.i("  serial  = ${cert.serialNumber}  valid ${cert.notBefore}..${cert.notAfter}")
+            PhoneTls(identity.keyStore, identity.password)
+        }.also { Thread(it, "gearslip-identity").start() }
 
         startWatchdog()
 

gearslip/src/main/java/app/seb3thehacker/gearslip/car/Prefetch.kt

@@ -1,13 +1,15 @@
 package app.seb3thehacker.gearslip.car
 
 import android.content.Context
+import app.seb3thehacker.gearslip.CertProvider
 import app.seb3thehacker.gearslip.GearslipLog
 import app.seb3thehacker.gearslip.mirror.PhoneApps
 import java.util.concurrent.Executors
 
 /**
  * Loads what the car screens show before anyone opens them: the car and media apps with their
- * icons, the phone's launcher apps, the weather and the calendar. Each screen paints from these
+ * icons, the phone's launcher apps, the weather and the calendar. Also unlocks the certificate,
+ * so a head unit's first message is answered at once. Each screen paints from these
  * results at once and refreshes behind them, so nothing waits on the package manager, the
  * network or the calendar provider.
  *
@@ -28,6 +30,7 @@ object Prefetch {
         val app = context.applicationContext
         worker.execute {
             val start = System.currentTimeMillis()
+            step("certificate") { CertProvider.warm(app) }
             step("launcher apps") { warmLauncherApps(app) }
             step("phone apps") { PhoneApps.warm(app) }
             step("weather and calendar") { warmDashboard(app) }