when composing, do not allow witnessed level to retreat

parent_composer.js

@@ -32,22 +32,24 @@ function pickParentUnits(conn, arrWitnesses, onDone){
 			var count_required_matches = constants.COUNT_WITNESSES - constants.MAX_WITNESS_LIST_MUTATIONS;
 			// we need at least one compatible parent, otherwise go deep
 			if (rows.filter(function(row){ return (row.count_matching_witnesses >= count_required_matches); }).length === 0)
-				return pickDeepParentUnits(conn, arrWitnesses, onDone);
-			onDone(null, rows.map(function(row){ return row.unit; }));
+				return pickDeepParentUnits(conn, arrWitnesses, null, onDone);
+			var arrParentUnits = rows.map(function(row){ return row.unit; });
+			checkWitnessedLevelNotRetreatingAndLookDeeper(conn, arrWitnesses, arrParentUnits, onDone);
 		}
 	);
 }
 
 // if we failed to find compatible parents among free units. 
 // (This may be the case if an attacker floods the network trying to shift the witness list)
-function pickDeepParentUnits(conn, arrWitnesses, onDone){
+function pickDeepParentUnits(conn, arrWitnesses, max_wl, onDone){
 	// fixed: an attacker could cover all free compatible units with his own incompatible ones, then those that were not on MC will be never included
 	//var cond = bDeep ? "is_on_main_chain=1" : "is_free=1";
 
+	var and_wl = (max_wl === null) ? '' : "AND witnessed_level<="+max_wl;
 	conn.query(
 		"SELECT unit \n\
 		FROM units \n\
-		WHERE +sequence='good' \n\
+		WHERE +sequence='good' "+and_wl+" \n\
 			AND ( \n\
 				SELECT COUNT(*) \n\
 				FROM unit_witnesses \n\
@@ -58,11 +60,23 @@ function pickDeepParentUnits(conn, arrWitnesses, onDone){
 		function(rows){
 			if (rows.length === 0)
 				return onDone("failed to find compatible parents: no deep units");
-			onDone(null, rows.map(function(row){ return row.unit; }));
+			var arrParentUnits = rows.map(function(row){ return row.unit; });
+			checkWitnessedLevelNotRetreatingAndLookDeeper(conn, arrWitnesses, arrParentUnits, onDone);
 		}
 	);
 }
 
+function checkWitnessedLevelNotRetreatingAndLookDeeper(conn, arrWitnesses, arrParentUnits, onDone){
+	storage.determineWitnessedLevelAndBestParent(conn, arrParentUnits, arrWitnesses, function(witnessed_level, best_parent_unit){
+		storage.readStaticUnitProps(conn, best_parent_unit, function(props){
+			if (witnessed_level >= props.witnessed_level)
+				return onDone(null, arrParentUnits);
+			console.log("witness level would retreat if parents = "+arrParentUnits.join(', ')+", will look for older parents");
+			pickDeepParentUnits(conn, arrWitnesses, witnessed_level, onDone);
+		});
+	});
+}
+
 function findLastStableMcBall(conn, arrWitnesses, onDone){
 	conn.query(
 		"SELECT ball, unit, main_chain_index FROM units JOIN balls USING(unit) \n\
@@ -94,7 +108,7 @@ function adjustLastStableMcBallAndParents(conn, last_stable_mc_ball_unit, arrPar
 		}
 		console.log('will adjust last stable ball because '+last_stable_mc_ball_unit+' is not stable in view of parents '+arrParentUnits.join(', '));
 		if (arrParentUnits.length > 1){ // select only one parent
-			pickDeepParentUnits(conn, arrWitnesses, function(err, arrAdjustedParentUnits){
+			pickDeepParentUnits(conn, arrWitnesses, null, function(err, arrAdjustedParentUnits){
 				if (err)
 					throw Error("pickDeepParentUnits in adjust failed: "+err);
 				adjustLastStableMcBallAndParents(conn, last_stable_mc_ball_unit, arrAdjustedParentUnits, arrWitnesses, handleAdjustedLastStableUnit);

storage.js

@@ -567,6 +567,38 @@ function determineIfWitnessAddressDefinitionsHaveReferences(conn, arrWitnesses,
 	);
 }
 
+function determineWitnessedLevelAndBestParent(conn, arrParentUnits, arrWitnesses, handleWitnessedLevelAndBestParent){
+	var arrCollectedWitnesses = [];
+	var my_best_parent_unit;
+
+	function addWitnessesAndGoUp(start_unit){
+		readStaticUnitProps(conn, start_unit, function(props){
+			var best_parent_unit = props.best_parent_unit;
+			var level = props.level;
+			if (level === null)
+				throw Error("null level in updateWitnessedLevel");
+			if (level === 0) // genesis
+				return handleWitnessedLevelAndBestParent(0, null);
+			readUnitAuthors(conn, start_unit, function(arrAuthors){
+				for (var i=0; i<arrAuthors.length; i++){
+					var address = arrAuthors[i];
+					if (arrWitnesses.indexOf(address) !== -1 && arrCollectedWitnesses.indexOf(address) === -1)
+						arrCollectedWitnesses.push(address);
+				}
+				(arrCollectedWitnesses.length < constants.MAJORITY_OF_WITNESSES) 
+					? addWitnessesAndGoUp(best_parent_unit) : handleWitnessedLevelAndBestParent(level, my_best_parent_unit);
+			});
+		});
+	}
+
+	determineBestParent(conn, {parent_units: arrParentUnits, witness_list_unit: 'none'}, arrWitnesses, function(best_parent_unit){
+		if (!best_parent_unit)
+			throw Error("no best parent of "+arrParentUnits.join(', '));
+		my_best_parent_unit = best_parent_unit;
+		addWitnessesAndGoUp(best_parent_unit);
+	});
+}
+
 
 /*
 function readWitnessesOnMcUnit(conn, main_chain_index, handleWitnesses){
@@ -655,7 +687,7 @@ function isGenesisBall(ball){
 
 function readUnitProps(conn, unit, handleProps){
 	conn.query(
-		"SELECT unit, level, latest_included_mc_index, main_chain_index, is_on_main_chain, is_free, is_stable FROM units WHERE unit=?", 
+		"SELECT unit, level, latest_included_mc_index, main_chain_index, is_on_main_chain, is_free, is_stable, witnessed_level FROM units WHERE unit=?", 
 		[unit], 
 		function(rows){
 			if (rows.length !== 1)
@@ -1371,6 +1403,7 @@ exports.loadAssetWithListOfAttestedAuthors = loadAssetWithListOfAttestedAuthors;
 
 exports.filterNewOrUnstableUnits = filterNewOrUnstableUnits;
 
+exports.determineWitnessedLevelAndBestParent = determineWitnessedLevelAndBestParent;
 exports.determineBestParent = determineBestParent;
 exports.determineIfHasWitnessListMutationsAlongMc = determineIfHasWitnessListMutationsAlongMc;