From da9371284625d2481ed496921505c8afd2dae1f0 Mon Sep 17 00:00:00 2001
From: Adam Ierymenko <adam.ierymenko@gmail.com>
Date: Wed, 28 Oct 2015 09:11:30 -0700
Subject: [PATCH] Clean up PUSH_DIRECT_PATH limits a bit more and make them a
 bit smarter.

---
 node/Constants.hpp      | 10 +++++-----
 node/IncomingPacket.cpp | 25 +++++++++++++++----------
 node/InetAddress.hpp    |  8 +++++++-
 3 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/node/Constants.hpp b/node/Constants.hpp
index 53cc64c7e..5a4d4a4de 100644
--- a/node/Constants.hpp
+++ b/node/Constants.hpp
@@ -347,11 +347,6 @@
  */
 #define ZT_DIRECT_PATH_PUSH_INTERVAL 120000
 
-/**
- * Maximum number of endpoints to contact per address type (to limit pushes like GitHub issue #235)
- */
-#define ZT_PUSH_DIRECT_PATHS_MAX_ENDPOINTS_PER_TYPE 5
-
 /**
  * Time horizon for push direct paths cutoff
  */
@@ -366,6 +361,11 @@
  */
 #define ZT_PUSH_DIRECT_PATHS_CUTOFF_LIMIT 5
 
+/**
+ * Maximum number of paths per IP scope (e.g. global, link-local) and family (e.g. v4/v6)
+ */
+#define ZT_PUSH_DIRECT_PATHS_MAX_PER_SCOPE_AND_FAMILY 1
+
 /**
  * A test pseudo-network-ID that can be joined
  *
diff --git a/node/IncomingPacket.cpp b/node/IncomingPacket.cpp
index e985b34c4..f06eb30c3 100644
--- a/node/IncomingPacket.cpp
+++ b/node/IncomingPacket.cpp
@@ -901,16 +901,19 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,const Sha
 {
 	try {
 		const uint64_t now = RR->node->now();
+
+		// First, subject this to a rate limit
 		if (!peer->shouldRespondToDirectPathPush(now)) {
 			TRACE("dropped PUSH_DIRECT_PATHS from %s(%s): circuit breaker tripped",source().toString().c_str(),_remoteAddress.toString().c_str());
 			return true;
 		}
 
-		const Path *currentBest = peer->getBestPath(now);
+		// Second, limit addresses by scope and type
+		uint8_t countPerScope[ZT_INETADDRESS_MAX_SCOPE+1][2]; // [][0] is v4, [][1] is v6
+		memset(countPerScope,0,sizeof(countPerScope));
 
 		unsigned int count = at<uint16_t>(ZT_PACKET_IDX_PAYLOAD);
 		unsigned int ptr = ZT_PACKET_IDX_PAYLOAD + 2;
-		unsigned int v4Count = 0,v6Count = 0;
 
 		while (count--) { // if ptr overflows Buffer will throw
 			// TODO: some flags are not yet implemented
@@ -925,20 +928,22 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,const Sha
 				case 4: {
 					InetAddress a(field(ptr,4),4,at<uint16_t>(ptr + 4));
 					if ( ((flags & 0x01) == 0) && (Path::isAddressValidForPath(a)) ) {
-						TRACE("attempting to contact %s at pushed direct path %s",peer->address().toString().c_str(),a.toString().c_str());
-						if (v4Count++ < ZT_PUSH_DIRECT_PATHS_MAX_ENDPOINTS_PER_TYPE) {
-							if ((!currentBest)||(currentBest->address() != a))
-								peer->attemptToContactAt(RR,_localAddress,a,now);
+						if (++countPerScope[(int)a.ipScope()][0] <= ZT_PUSH_DIRECT_PATHS_MAX_PER_SCOPE_AND_FAMILY) {
+							TRACE("attempting to contact %s at pushed direct path %s",peer->address().toString().c_str(),a.toString().c_str());
+							peer->attemptToContactAt(RR,_localAddress,a,now);
+						} else {
+							TRACE("ignoring contact for %s at %s -- too many per scope",peer->address().toString().c_str(),a.toString().c_str());
 						}
 					}
 				}	break;
 				case 6: {
 					InetAddress a(field(ptr,16),16,at<uint16_t>(ptr + 16));
 					if ( ((flags & 0x01) == 0) && (Path::isAddressValidForPath(a)) ) {
-						TRACE("attempting to contact %s at pushed direct path %s",peer->address().toString().c_str(),a.toString().c_str());
-						if (v6Count++ < ZT_PUSH_DIRECT_PATHS_MAX_ENDPOINTS_PER_TYPE) {
-							if ((!currentBest)||(currentBest->address() != a))
-								peer->attemptToContactAt(RR,_localAddress,a,now);
+						if (++countPerScope[(int)a.ipScope()][1] <= ZT_PUSH_DIRECT_PATHS_MAX_PER_SCOPE_AND_FAMILY) {
+							TRACE("attempting to contact %s at pushed direct path %s",peer->address().toString().c_str(),a.toString().c_str());
+							peer->attemptToContactAt(RR,_localAddress,a,now);
+						} else {
+							TRACE("ignoring contact for %s at %s -- too many per scope",peer->address().toString().c_str(),a.toString().c_str());
 						}
 					}
 				}	break;
diff --git a/node/InetAddress.hpp b/node/InetAddress.hpp
index fcbed4b15..5e5eb06ee 100644
--- a/node/InetAddress.hpp
+++ b/node/InetAddress.hpp
@@ -42,6 +42,11 @@
 
 namespace ZeroTier {
 
+/**
+ * Maximum integer value of enum IpScope
+ */
+#define ZT_INETADDRESS_MAX_SCOPE 7
+
 /**
  * Extends sockaddr_storage with friendly C++ methods
  *
@@ -66,7 +71,8 @@ struct InetAddress : public sockaddr_storage
 	 * IP address scope
 	 *
 	 * Note that these values are in ascending order of path preference and
-	 * MUST remain that way or Path must be changed to reflect.
+	 * MUST remain that way or Path must be changed to reflect. Also be sure
+	 * to change ZT_INETADDRESS_MAX_SCOPE if the max changes.
 	 */
 	enum IpScope
 	{