From 0a666df164f2ef04a15acd6378ab3ef64dde3246 Mon Sep 17 00:00:00 2001
From: akwizgran <michael@briarproject.org>
Date: Thu, 12 Mar 2020 16:43:46 +0000
Subject: [PATCH] Correctly handle connectivity events on IPv6-only networks.

---
 .../plugin/tcp/AndroidLanTcpPlugin.java       | 21 ++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java b/bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java
index 3510e571b..cabb2f653 100644
--- a/bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java
+++ b/bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java
@@ -252,7 +252,7 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 		connectionStatusExecutor.execute(() -> {
 			State s = getState();
 			if (s != ACTIVE && s != INACTIVE) return;
-			Pair<InetAddress, Boolean> wifi = getWifiIpv4Address();
+			Pair<InetAddress, Boolean> wifi = getPreferredWifiAddress();
 			if (wifi == null) {
 				LOG.info("Not connected to wifi");
 				socketFactory = SocketFactory.getDefault();
@@ -280,4 +280,23 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 			}
 		});
 	}
+
+	/**
+	 * Returns a {@link Pair} where the first element is an IP address (IPv4 if
+	 * available, otherwise IPv6) of the wifi interface and the second element
+	 * is true if this device is providing an access point, or false if this
+	 * device is a client. Returns null if this device isn't connected to wifi
+	 * as an access point or client.
+	 */
+	@Nullable
+	private Pair<InetAddress, Boolean> getPreferredWifiAddress() {
+		Pair<InetAddress, Boolean> wifi = getWifiIpv4Address();
+		// If there's no wifi IPv4 address, we might be a client on an
+		// IPv6-only wifi network. We can only detect this on API 21+
+		if (wifi == null && SDK_INT >= 21) {
+			InetAddress ipv6 = getWifiClientIpv6Address();
+			if (ipv6 != null) return new Pair<>(ipv6, false);
+		}
+		return wifi;
+	}
 }
\ No newline at end of file