2 files changed, 49 insertions, 1 deletions

diff --git a/java/src/com/zerotier/sdk/Node.java b/java/src/com/zerotier/sdk/Node.java
index 4bc6e184..7b111f74 100644
--- a/java/src/com/zerotier/sdk/Node.java
+++ b/java/src/com/zerotier/sdk/Node.java
@@ -74,6 +74,7 @@ public class Node {
     private final EventListener eventListener;
     private final VirtualNetworkFrameListener frameListener;
     private final VirtualNetworkConfigListener configListener;
+    private final PathChecker pathChecker;
     
     /**
      * Create a new ZeroTier One node
@@ -95,7 +96,8 @@ public class Node {
                 PacketSender sender,
                 EventListener eventListener,
                 VirtualNetworkFrameListener frameListener,
-                VirtualNetworkConfigListener configListener) throws NodeException
+                VirtualNetworkConfigListener configListener,
+                PathChecker pathChecker) throws NodeException
 	{
         this.nodeId = now;
 
@@ -105,6 +107,7 @@ public class Node {
         this.eventListener = eventListener;
         this.frameListener = frameListener;
         this.configListener = configListener;
+        this.pathChecker = pathChecker;
 
         ResultCode rc = node_init(now);
         if(rc != ResultCode.RESULT_OK)
diff --git a/java/src/com/zerotier/sdk/PathChecker.java b/java/src/com/zerotier/sdk/PathChecker.java
new file mode 100644
index 00000000..3e02f112
--- /dev/null
+++ b/java/src/com/zerotier/sdk/PathChecker.java
@@ -0,0 +1,45 @@
+/*
+ * ZeroTier One - Network Virtualization Everywhere
+ * Copyright (C) 2011-2017  ZeroTier, Inc.  https://www.zerotier.com/
+ */
+
+package com.zerotier.sdk;
+
+import java.net.InetSocketAddress;
+
+public interface PathChecker {
+    /**
+     * Callback to check whether a path should be used for ZeroTier traffic
+     *
+     * This function must return true if the path should be used.
+     *
+     * If no path check function is specified, ZeroTier will still exclude paths
+     * that overlap with ZeroTier-assigned and managed IP address blocks. But the
+     * use of a path check function is recommended to ensure that recursion does
+     * not occur in cases where addresses are assigned by the OS or managed by
+     * an out of band mechanism like DHCP. The path check function should examine
+     * all configured ZeroTier interfaces and check to ensure that the supplied
+     * addresses will not result in ZeroTier traffic being sent over a ZeroTier
+     * interface (recursion).
+     *
+     * Obviously this is not required in configurations where this can't happen,
+     * such as network containers or embedded.
+     *
+     * @param ztAddress ZeroTier address or 0 for none/any
+     * @param localAddress Local interface address
+     * @param remoteAddress remote address
+     */
+    boolean onPathCheck(long ztAddress, InetSocketAddress localAddress, InetSocketAddress remoteAddress);
+
+    /**
+     * Function to get physical addresses for ZeroTier peers
+     *
+     * If provided this function will be occasionally called to get physical
+     * addresses that might be tried to reach a ZeroTier address.
+     *
+     * @param ztAddress ZeroTier address (least significant 40 bits)
+     * @param ss_family desired address family or -1 for any
+     * @return address and port of ztAddress or null
+     */
+    InetSocketAddress onPathLookup(long ztAddress, int ss_family);
+}