Supply missing pieces of path change

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

2 files changed, 12 insertions, 10 deletions

diff --git a/WireGuard/WireGuardNetworkExtension/PacketTunnelProvider.swift b/WireGuard/WireGuardNetworkExtension/PacketTunnelProvider.swift
index 04e9637..f5f0296 100644
--- a/WireGuard/WireGuardNetworkExtension/PacketTunnelProvider.swift
+++ b/WireGuard/WireGuardNetworkExtension/PacketTunnelProvider.swift
@@ -95,16 +95,18 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
         networkMonitor = NWPathMonitor()
         networkMonitor?.pathUpdateHandler = { path in
             guard handle >= 0 else { return }
-            
             if path.status == .satisfied {
-                let endpointString = packetTunnelSettingsGenerator.endpointUapiConfiguration()
-                
-                let endpointGoString = endpointString.withCString {
-                    gostring_t(p: $0, n: endpointString.utf8.count)
+                wg_log(.debug, message: "Network change detected, re-establishing sockets and IPs: \(path.availableInterfaces)")
+                let endpointString = packetTunnelSettingsGenerator.endpointUapiConfiguration(currentListenPort: wgGetListenPort(handle))
+                let err = endpointString.withCString {
+                    wgSetConfig(handle,  gostring_t(p: $0, n: endpointString.utf8.count))
+                }
+                if err == -EADDRINUSE {
+                    let endpointString = packetTunnelSettingsGenerator.endpointUapiConfiguration(currentListenPort: 0)
+                    _ = endpointString.withCString {
+                        wgSetConfig(handle,  gostring_t(p: $0, n: endpointString.utf8.count))
+                    }
                 }
-                
-                wg_log(.debug, staticMessage: "Network change detected, calling wgSetConfig")
-                wgSetConfig(handle, endpointGoString)
             }
         }
         networkMonitor?.start(queue: DispatchQueue(label: "NetworkMonitor"))
diff --git a/WireGuard/WireGuardNetworkExtension/PacketTunnelSettingsGenerator.swift b/WireGuard/WireGuardNetworkExtension/PacketTunnelSettingsGenerator.swift
index 0eea95a..61e161e 100644
--- a/WireGuard/WireGuardNetworkExtension/PacketTunnelSettingsGenerator.swift
+++ b/WireGuard/WireGuardNetworkExtension/PacketTunnelSettingsGenerator.swift
@@ -15,8 +15,8 @@ class PacketTunnelSettingsGenerator {
         self.resolvedEndpoints = resolvedEndpoints
     }
 
-    func endpointUapiConfiguration() -> String {
-        var wgSettings = "listen_port=\(tunnelConfiguration.interface.listenPort ?? 0)\n"
+    func endpointUapiConfiguration(currentListenPort: UInt16) -> String {
+        var wgSettings = "listen_port=\(tunnelConfiguration.interface.listenPort ?? currentListenPort)\n"
 
         for (i, peer) in tunnelConfiguration.peers.enumerated() {
             wgSettings.append("public_key=\(peer.publicKey.hexEncodedString())\n")