Moderate efficiency improvement on multicast gather result parsing, and go ahead and keep track of total known peers.

node/IncomingPacket.cpp

@@ -892,20 +892,9 @@ void IncomingPacket::_sendErrorNeedCertificate(const RuntimeEnvironment *RR,cons
 
 void IncomingPacket::_parseGatherResults(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer,uint64_t nwid,const MulticastGroup &mg,unsigned int offset)
 {
-	//unsigned int totalKnown = at<uint32_t>(offset);
+	unsigned int totalKnown = at<uint32_t>(offset);
 	unsigned int count = at<uint16_t>(offset + 4);
-	const unsigned char *p = (const unsigned char *)data() + offset + 6;
-	const unsigned char *e = (const unsigned char *)data() + size();
-	Address atmp;
-	uint64_t now = Utils::now();
-	for(unsigned int i=0;i<count;++i) {
-		const unsigned char *n = p + ZT_ADDRESS_LENGTH;
-		if (n > e)
-			break;
-		atmp.setTo(p,ZT_ADDRESS_LENGTH);
-		RR->mc->add(now,nwid,mg,peer->address(),atmp);
-		p = n;
-	}
+	RR->mc->addMultiple(Utils::now(),nwid,mg,peer->address(),field(offset + 6,count * 5),count,totalKnown);
 }
 
 } // namespace ZeroTier

node/Multicaster.cpp

@@ -52,6 +52,20 @@ Multicaster::~Multicaster()
 {
 }
 
+void Multicaster::addMultiple(uint64_t now,uint64_t nwid,const MulticastGroup &mg,const Address &learnedFrom,const void *addresses,unsigned int count,unsigned int totalKnown)
+{
+	const unsigned char *p = (const unsigned char *)addresses;
+	const unsigned char *e = p + (5 * count);
+	Mutex::Lock _l(_groups_m);
+	MulticastGroupStatus &gs = _groups[std::pair<uint64_t,MulticastGroup>(nwid,mg)];
+	while (p != e) {
+		_add(now,nwid,mg,gs,learnedFrom,Address(p,5));
+		p += 5;
+	}
+	if (RR->topology->isSupernode(learnedFrom))
+		gs.totalKnownMembers = totalKnown;
+}
+
 unsigned int Multicaster::gather(const Address &queryingPeer,uint64_t nwid,const MulticastGroup &mg,Packet &appendTo,unsigned int limit) const
 {
 	unsigned char *p;
@@ -337,7 +351,7 @@ void Multicaster::clean(uint64_t now)
 				 * learned peers. For peers with no active Peer record, we use the time we last learned
 				 * about them minus one day (a large constant) to put these at the bottom of the list.
 				 * List is sorted in ascending order of rank and multicasts are sent last-to-first. */
-				if (writer->learnedFrom) {
+				if (writer->learnedFrom != writer->address) {
 					SharedPtr<Peer> p(RR->topology->getPeer(writer->learnedFrom));
 					if (p)
 						writer->rank = (RR->topology->amSupernode() ? p->lastDirectReceive() : p->lastUnicastFrame()) - ZT_MULTICAST_LIKE_EXPIRE;
@@ -381,9 +395,7 @@ void Multicaster::_add(uint64_t now,uint64_t nwid,const MulticastGroup &mg,Multi
 	// Update timestamp and learnedFrom if existing
 	for(std::vector<MulticastGroupMember>::iterator m(gs.members.begin());m!=gs.members.end();++m) {
 		if (m->address == member) {
-			// learnedFrom is NULL (zero) if we've learned this directly via MULTICAST_LIKE, at which
-			// point this becomes a first-order connection.
-			if (m->learnedFrom)
+			if (m->learnedFrom != member) // once we learn it directly, remember this forever
 				m->learnedFrom = learnedFrom;
 			m->timestamp = now;
 			return;

node/Multicaster.hpp

@@ -62,7 +62,7 @@ private:
 		MulticastGroupMember(const Address &a,const Address &lf,uint64_t ts) : address(a),learnedFrom(lf),timestamp(ts),rank(0) {}
 
 		Address address;
-		Address learnedFrom; // NULL/0 for addresses directly learned from LIKE
+		Address learnedFrom;
 		uint64_t timestamp; // time of last LIKE/OK(GATHER)
 		uint64_t rank; // used by sorting algorithm in clean()
 
@@ -72,9 +72,10 @@ private:
 
 	struct MulticastGroupStatus
 	{
-		MulticastGroupStatus() : lastExplicitGather(0) {}
+		MulticastGroupStatus() : lastExplicitGather(0),totalKnownMembers(0) {}
 
 		uint64_t lastExplicitGather;
+		unsigned int totalKnownMembers; // 0 if unknown
 		std::list<OutboundMulticast> txQueue; // pending outbound multicasts
 		std::vector<MulticastGroupMember> members; // members of this group
 	};
@@ -89,7 +90,7 @@ public:
 	 * @param now Current time
 	 * @param nwid Network ID
 	 * @param mg Multicast group
-	 * @param learnedFrom Address from which we learned this member or NULL/0 Address if direct
+	 * @param learnedFrom Address from which we learned this member
 	 * @param member New member address
 	 */
 	inline void add(uint64_t now,uint64_t nwid,const MulticastGroup &mg,const Address &learnedFrom,const Address &member)
@@ -98,6 +99,21 @@ public:
 		_add(now,nwid,mg,_groups[std::pair<uint64_t,MulticastGroup>(nwid,mg)],learnedFrom,member);
 	}
 
+	/**
+	 * Add multiple addresses from a binary array of 5-byte address fields
+	 *
+	 * It's up to the caller to check bounds on the array before calling this.
+	 *
+	 * @param now Current time
+	 * @param nwid Network ID
+	 * @param mg Multicast group
+	 * @param learnedFrom Peer from which we received this list
+	 * @param addresses Raw binary addresses in big-endian format, as a series of 5-byte fields
+	 * @param count Number of addresses
+	 * @param totalKnown Total number of known addresses as reported by peer
+	 */
+	void addMultiple(uint64_t now,uint64_t nwid,const MulticastGroup &mg,const Address &learnedFrom,const void *addresses,unsigned int count,unsigned int totalKnown);
+
 	/**
 	 * Append gather results to a packet by choosing registered multicast recipients at random
 	 *