Clean up handling of COMs, network access control, and fix a backward compatiblity issue.

node/Membership.hpp

@@ -154,6 +154,21 @@ public:
 		return nconf.com.agreesWith(_com);
 	}
 
+	/**
+	 * @return True if this member has been on this network recently (or network is public)
+	 */
+	inline bool recentlyAllowedOnNetwork(const NetworkConfig &nconf) const
+	{
+		if (nconf.isPublic())
+			return true;
+		if (_com) {
+			const uint64_t a = _com.timestamp().first;
+			const std::pair<uint64_t,uint64_t> b(nconf.com.timestamp());
+			return ((a <= b.first) ? ((b.first - a) <= ZT_PEER_ACTIVITY_TIMEOUT) : true);
+		}
+		return false;
+	}
+
 	/**
 	 * Check whether a capability or tag is within its max delta from the timestamp of our network config and newer than any blacklist cutoff time
 	 *