Merge pull request #1218 from wpaulino/filter-type-verification

server: ensure we only fetch filters we know of

server.go

@@ -762,8 +762,21 @@ func (sp *serverPeer) OnGetCFilters(_ *peer.Peer, msg *wire.MsgGetCFilters) {
 		return
 	}
 
-	hashes, err := sp.server.chain.HeightToHashRange(int32(msg.StartHeight),
+	// We'll also ensure that the remote party is requesting a set of
-		&msg.StopHash, wire.MaxGetCFiltersReqRange)
+	// filters that we actually currently maintain.
+	switch msg.FilterType {
+	case wire.GCSFilterRegular:
+		break
+
+	default:
+		peerLog.Debug("Filter request for unknown filter: %v",
+			msg.FilterType)
+		return
+	}
+
+	hashes, err := sp.server.chain.HeightToHashRange(
+		int32(msg.StartHeight), &msg.StopHash, wire.MaxGetCFiltersReqRange,
+	)
 	if err != nil {
 		peerLog.Debugf("Invalid getcfilters request: %v", err)
 		return
@@ -776,8 +789,9 @@ func (sp *serverPeer) OnGetCFilters(_ *peer.Peer, msg *wire.MsgGetCFilters) {
 		hashPtrs[i] = &hashes[i]
 	}
 
-	filters, err := sp.server.cfIndex.FiltersByBlockHashes(hashPtrs,
+	filters, err := sp.server.cfIndex.FiltersByBlockHashes(
-		msg.FilterType)
+		hashPtrs, msg.FilterType,
+	)
 	if err != nil {
 		peerLog.Errorf("Error retrieving cfilters: %v", err)
 		return
@@ -785,10 +799,14 @@ func (sp *serverPeer) OnGetCFilters(_ *peer.Peer, msg *wire.MsgGetCFilters) {
 
 	for i, filterBytes := range filters {
 		if len(filterBytes) == 0 {
-			peerLog.Warnf("Could not obtain cfilter for %v", hashes[i])
+			peerLog.Warnf("Could not obtain cfilter for %v",
+				hashes[i])
 			return
 		}
-		filterMsg := wire.NewMsgCFilter(msg.FilterType, &hashes[i], filterBytes)
+
+		filterMsg := wire.NewMsgCFilter(
+			msg.FilterType, &hashes[i], filterBytes,
+		)
 		sp.QueueMessage(filterMsg, nil)
 	}
 }
@@ -800,19 +818,32 @@ func (sp *serverPeer) OnGetCFHeaders(_ *peer.Peer, msg *wire.MsgGetCFHeaders) {
 		return
 	}
 
+	// We'll also ensure that the remote party is requesting a set of
+	// headers for filters that we actually currently maintain.
+	switch msg.FilterType {
+	case wire.GCSFilterRegular:
+		break
+
+	default:
+		peerLog.Debug("Filter request for unknown headers for "+
+			"filter: %v", msg.FilterType)
+		return
+	}
+
 	startHeight := int32(msg.StartHeight)
 	maxResults := wire.MaxCFHeadersPerMsg
 
-	// If StartHeight is positive, fetch the predecessor block hash so we can
+	// If StartHeight is positive, fetch the predecessor block hash so we
-	// populate the PrevFilterHeader field.
+	// can populate the PrevFilterHeader field.
 	if msg.StartHeight > 0 {
 		startHeight--
 		maxResults++
 	}
 
 	// Fetch the hashes from the block index.
-	hashList, err := sp.server.chain.HeightToHashRange(startHeight,
+	hashList, err := sp.server.chain.HeightToHashRange(
-		&msg.StopHash, maxResults)
+		startHeight, &msg.StopHash, maxResults,
+	)
 	if err != nil {
 		peerLog.Debugf("Invalid getcfheaders request: %v", err)
 	}
@@ -833,8 +864,9 @@ func (sp *serverPeer) OnGetCFHeaders(_ *peer.Peer, msg *wire.MsgGetCFHeaders) {
 	}
 
 	// Fetch the raw filter hash bytes from the database for all blocks.
-	filterHashes, err := sp.server.cfIndex.FilterHashesByBlockHashes(hashPtrs,
+	filterHashes, err := sp.server.cfIndex.FilterHashesByBlockHashes(
-		msg.FilterType)
+		hashPtrs, msg.FilterType,
+	)
 	if err != nil {
 		peerLog.Errorf("Error retrieving cfilter hashes: %v", err)
 		return
@@ -892,6 +924,7 @@ func (sp *serverPeer) OnGetCFHeaders(_ *peer.Peer, msg *wire.MsgGetCFHeaders) {
 
 	headersMsg.FilterType = msg.FilterType
 	headersMsg.StopHash = msg.StopHash
+
 	sp.QueueMessage(headersMsg, nil)
 }
 
@@ -902,42 +935,78 @@ func (sp *serverPeer) OnGetCFCheckpt(_ *peer.Peer, msg *wire.MsgGetCFCheckpt) {
 		return
 	}
 
-	blockHashes, err := sp.server.chain.IntervalBlockHashes(&msg.StopHash,
+	// We'll also ensure that the remote party is requesting a set of
-		wire.CFCheckptInterval)
+	// checkpoints for filters that we actually currently maintain.
+	switch msg.FilterType {
+	case wire.GCSFilterRegular:
+		break
+
+	default:
+		peerLog.Debug("Filter request for unknown checkpoints for "+
+			"filter: %v", msg.FilterType)
+		return
+	}
+
+	// Now that we know the client is fetching a filter that we know of,
+	// we'll fetch the block hashes et each check point interval so we can
+	// compare against our cache, and create new check points if necessary.
+	blockHashes, err := sp.server.chain.IntervalBlockHashes(
+		&msg.StopHash, wire.CFCheckptInterval,
+	)
 	if err != nil {
 		peerLog.Debugf("Invalid getcfilters request: %v", err)
 		return
 	}
 
+	checkptMsg := wire.NewMsgCFCheckpt(
+		msg.FilterType, &msg.StopHash, len(blockHashes),
+	)
+
+	// Fetch the current existing cache so we can decide if we need to
+	// extend it or if its adequate as is.
+	sp.server.cfCheckptCachesMtx.Lock()
+	checkptCache := sp.server.cfCheckptCaches[msg.FilterType]
+
+	// If the set of block hashes is beyond the current size of the cache,
+	// then we'll expand the size of the cache and also retain the write
+	// lock.
 	var updateCache bool
-	var checkptCache []cfHeaderKV
-
 	if len(blockHashes) > len(checkptCache) {
-		// Update the cache if the checkpoint chain is longer than the cached
+		// Now that we know we'll need to modify the size of the cache,
-		// one. This ensures that the cache is relatively stable and mostly
+		// we'll defer the release of the write lock so we don't
-		// overlaps with the best chain, since it follows the longest chain
+		// forget.
-		// heuristic.
-		updateCache = true
-
-		// Take write lock because we are going to update cache.
-		sp.server.cfCheckptCachesMtx.Lock()
 		defer sp.server.cfCheckptCachesMtx.Unlock()
 
-		// Grow the checkptCache to be the length of blockHashes.
+		// We'll mark that we need to update the cache for below and
+		// also expand the size of the cache in place.
+		updateCache = true
+
 		additionalLength := len(blockHashes) - len(checkptCache)
-		checkptCache = append(sp.server.cfCheckptCaches[msg.FilterType],
+		newEntries := make([]cfHeaderKV, additionalLength)
-			make([]cfHeaderKV, additionalLength)...)
+
+		peerLog.Infof("Growing size of checkpoint cache from %v to %v "+
+			"block hashes", len(checkptCache), len(blockHashes))
+
+		checkptCache = append(
+			sp.server.cfCheckptCaches[msg.FilterType],
+			newEntries...,
+		)
 	} else {
-		updateCache = false
+		// Otherwise, we'll release the write lock, then grab the read
-
+		// lock, as the cache is already properly sized.
-		// Take reader lock because we are not going to update cache.
+		sp.server.cfCheckptCachesMtx.Unlock()
 		sp.server.cfCheckptCachesMtx.RLock()
-		defer sp.server.cfCheckptCachesMtx.RUnlock()
 
-		checkptCache = sp.server.cfCheckptCaches[msg.FilterType]
+		peerLog.Tracef("Serving stale cache of size %v",
+			len(checkptCache))
+
+		defer sp.server.cfCheckptCachesMtx.RUnlock()
 	}
 
-	// Iterate backwards until the block hash is found in the cache.
+	// Now that we know the cache is of an appropriate size, we'll iterate
+	// backwards until the find the block hash. We do this as it's possible
+	// a re-org has occurred so items in the db are now in the main china
+	// while the cache has been partially invalidated.
 	var forkIdx int
 	for forkIdx = len(checkptCache); forkIdx > 0; forkIdx-- {
 		if checkptCache[forkIdx-1].blockHash == blockHashes[forkIdx-1] {
@@ -945,29 +1014,33 @@ func (sp *serverPeer) OnGetCFCheckpt(_ *peer.Peer, msg *wire.MsgGetCFCheckpt) {
 		}
 	}
 
-	// Populate results with cached checkpoints.
+	// Now that we know the how much of the cache is relevant for this
-	checkptMsg := wire.NewMsgCFCheckpt(msg.FilterType, &msg.StopHash,
+	// query, we'll populate our check point message with the cache as is.
-		len(blockHashes))
+	// Shortly below, we'll populate the new elements of the cache.
 	for i := 0; i < forkIdx; i++ {
 		checkptMsg.AddCFHeader(&checkptCache[i].filterHeader)
 	}
 
-	// Look up any filter headers that aren't cached.
+	// We'll now collect the set of hashes that are beyond our cache so we
+	// can look up the filter headers to populate the final cache.
 	blockHashPtrs := make([]*chainhash.Hash, 0, len(blockHashes)-forkIdx)
 	for i := forkIdx; i < len(blockHashes); i++ {
 		blockHashPtrs = append(blockHashPtrs, &blockHashes[i])
 	}
-
+	filterHeaders, err := sp.server.cfIndex.FilterHeadersByBlockHashes(
-	filterHeaders, err := sp.server.cfIndex.FilterHeadersByBlockHashes(blockHashPtrs,
+		blockHashPtrs, msg.FilterType,
-		msg.FilterType)
+	)
 	if err != nil {
 		peerLog.Errorf("Error retrieving cfilter headers: %v", err)
 		return
 	}
 
+	// Now that we have the full set of filter headers, we'll add them to
+	// the checkpoint message, and also update our cache in line.
 	for i, filterHeaderBytes := range filterHeaders {
 		if len(filterHeaderBytes) == 0 {
-			peerLog.Warnf("Could not obtain CF header for %v", blockHashPtrs[i])
+			peerLog.Warnf("Could not obtain CF header for %v",
+				blockHashPtrs[i])
 			return
 		}
 
@@ -979,6 +1052,9 @@ func (sp *serverPeer) OnGetCFCheckpt(_ *peer.Peer, msg *wire.MsgGetCFCheckpt) {
 		}
 
 		checkptMsg.AddCFHeader(filterHeader)
+
+		// If the new main chain is longer than what's in the cache,
+		// then we'll override it beyond the fork point.
 		if updateCache {
 			checkptCache[forkIdx+i] = cfHeaderKV{
 				blockHash:    blockHashes[forkIdx+i],
@@ -987,6 +1063,8 @@ func (sp *serverPeer) OnGetCFCheckpt(_ *peer.Peer, msg *wire.MsgGetCFCheckpt) {
 		}
 	}
 
+	// Finally, we'll update the cache if we need to, and send the final
+	// message back to the requesting peer.
 	if updateCache {
 		sp.server.cfCheckptCaches[msg.FilterType] = checkptCache
 	}