Discovery: wide-area bridge DNS-SD

# Conflicts:
#	apps/ios/Sources/Bridge/BridgeDiscoveryModel.swift
#	src/cli/dns-cli.ts

apps/android/app/src/main/java/com/steipete/clawdis/node/bridge/BonjourEscapes.kt

@@ -0,0 +1,30 @@
+package com.steipete.clawdis.node.bridge
+
+object BonjourEscapes {
+  fun decode(input: String): String {
+    if (input.isEmpty()) return input
+
+    val out = StringBuilder(input.length)
+    var i = 0
+    while (i < input.length) {
+      if (input[i] == '\\' && i + 3 < input.length) {
+        val d0 = input[i + 1]
+        val d1 = input[i + 2]
+        val d2 = input[i + 3]
+        if (d0.isDigit() && d1.isDigit() && d2.isDigit()) {
+          val value =
+            ((d0.code - '0'.code) * 100) + ((d1.code - '0'.code) * 10) + (d2.code - '0'.code)
+          if (value in 0..0x10FFFF) {
+            out.appendCodePoint(value)
+            i += 4
+            continue
+          }
+        }
+      }
+
+      out.append(input[i])
+      i += 1
+    }
+    return out.toString()
+  }
+}

apps/android/app/src/main/java/com/steipete/clawdis/node/bridge/BridgeDiscovery.kt

@@ -1,10 +1,12 @@
 package com.steipete.clawdis.node.bridge
 
 import android.content.Context
+import android.net.ConnectivityManager
 import android.net.nsd.NsdManager
 import android.net.nsd.NsdServiceInfo
 import android.os.Build
 import java.net.InetAddress
+import java.time.Duration
 import java.util.concurrent.ConcurrentHashMap
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
@@ -14,6 +16,7 @@ import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.launch
+import org.xbill.DNS.ExtendedResolver
 import org.xbill.DNS.Lookup
 import org.xbill.DNS.PTRRecord
 import org.xbill.DNS.SRVRecord
@@ -25,6 +28,7 @@ class BridgeDiscovery(
   private val scope: CoroutineScope,
 ) {
   private val nsd = context.getSystemService(NsdManager::class.java)
+  private val connectivity = context.getSystemService(ConnectivityManager::class.java)
   private val serviceType = "_clawdis-bridge._tcp."
   private val wideAreaDomain = "clawdis.internal."
 
@@ -100,8 +104,10 @@ class BridgeDiscovery(
           val port = resolved.port
           if (port <= 0) return
 
-          val displayName = txt(resolved, "displayName") ?: resolved.serviceName
-          val id = stableId(resolved.serviceName, "local.")
+          val rawServiceName = resolved.serviceName
+          val serviceName = BonjourEscapes.decode(rawServiceName)
+          val displayName = BonjourEscapes.decode(txt(resolved, "displayName") ?: serviceName)
+          val id = stableId(serviceName, "local.")
           localById[id] = BridgeEndpoint(stableId = id, name = displayName, host = host, port = port)
           publish()
         }
@@ -133,13 +139,15 @@ class BridgeDiscovery(
   }
 
   private suspend fun refreshUnicast(domain: String) {
+    val resolver = createUnicastResolver()
     val ptrName = "${serviceType}${domain}"
-    val ptrRecords = lookup(ptrName, Type.PTR).mapNotNull { it as? PTRRecord }
+    val ptrRecords = lookup(ptrName, Type.PTR, resolver).mapNotNull { it as? PTRRecord }
 
     val next = LinkedHashMap<String, BridgeEndpoint>()
     for (ptr in ptrRecords) {
       val instanceFqdn = ptr.target.toString()
-      val srv = lookup(instanceFqdn, Type.SRV).firstOrNull { it is SRVRecord } as? SRVRecord ?: continue
+      val srv =
+        lookup(instanceFqdn, Type.SRV, resolver).firstOrNull { it is SRVRecord } as? SRVRecord ?: continue
       val port = srv.port
       if (port <= 0) continue
 
@@ -152,9 +160,9 @@ class BridgeDiscovery(
           null
         } ?: continue
 
-      val txt = lookup(instanceFqdn, Type.TXT).mapNotNull { it as? TXTRecord }
-      val instanceName = decodeInstanceName(instanceFqdn, domain)
-      val displayName = txtValue(txt, "displayName") ?: instanceName
+      val txt = lookup(instanceFqdn, Type.TXT, resolver).mapNotNull { it as? TXTRecord }
+      val instanceName = BonjourEscapes.decode(decodeInstanceName(instanceFqdn, domain))
+      val displayName = BonjourEscapes.decode(txtValue(txt, "displayName") ?: instanceName)
       val id = stableId(instanceName, domain)
       next[id] = BridgeEndpoint(stableId = id, name = displayName, host = host, port = port)
     }
@@ -179,15 +187,41 @@ class BridgeDiscovery(
     return raw.removeSuffix(".")
   }
 
-  private fun lookup(name: String, type: Int): List<org.xbill.DNS.Record> {
+  private fun lookup(name: String, type: Int, resolver: org.xbill.DNS.Resolver?): List<org.xbill.DNS.Record> {
     return try {
-      val out = Lookup(name, type).run() ?: return emptyList()
+      val lookup = Lookup(name, type)
+      if (resolver != null) {
+        lookup.setResolver(resolver)
+        lookup.setCache(null)
+      }
+      val out = lookup.run() ?: return emptyList()
       out.toList()
     } catch (_: Throwable) {
       emptyList()
     }
   }
 
+  private fun createUnicastResolver(): org.xbill.DNS.Resolver? {
+    val cm = connectivity ?: return null
+    val net = cm.activeNetwork ?: return null
+    val dnsServers = cm.getLinkProperties(net)?.dnsServers ?: return null
+    val addrs =
+      dnsServers
+        .mapNotNull { it.hostAddress }
+        .map { it.trim() }
+        .filter { it.isNotEmpty() }
+        .distinct()
+    if (addrs.isEmpty()) return null
+
+    return try {
+      ExtendedResolver(addrs.toTypedArray()).apply {
+        setTimeout(Duration.ofMillis(1500))
+      }
+    } catch (_: Throwable) {
+      null
+    }
+  }
+
   private fun txtValue(records: List<TXTRecord>, key: String): String? {
     val prefix = "$key="
     for (r in records) {

apps/android/app/src/test/java/com/steipete/clawdis/node/bridge/BonjourEscapesTest.kt

@@ -0,0 +1,19 @@
+package com.steipete.clawdis.node.bridge
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class BonjourEscapesTest {
+  @Test
+  fun decodeNoop() {
+    assertEquals("", BonjourEscapes.decode(""))
+    assertEquals("hello", BonjourEscapes.decode("hello"))
+  }
+
+  @Test
+  fun decodeDecodesDecimalEscapes() {
+    assertEquals("Clawdis Gateway", BonjourEscapes.decode("Clawdis\\032Gateway"))
+    assertEquals("A B", BonjourEscapes.decode("A\\032B"))
+  }
+}
+