private void addMetadataIter(CfgManipulator cfgManipulator, GraphRandomStateGenerator randomStateGenerator, MethodCfg originalMethodCfg, MethodCfg methodCfg, BasicBlock startBasicBlock, LocalDefinition intStateLocal, LocalDefinition currentNodeLocal) {
int currentValidPathId;
// create transformation metadata for the start basic block
GraphTransformerMetadataBasicBlock metadata = new GraphTransformerMetadataBasicBlock();
for (currentValidPathId = 0; currentValidPathId < this.graph.graphValidPathCount; currentValidPathId++) {
BasicBlockGraphNodeLink link = new BasicBlockGraphNodeLink(this.graph.startingNode, currentValidPathId);
metadata.correspondingGraphNodes.Add(link);
}
startBasicBlock.transformationMetadata.Add(metadata);
// create a list of basic blocks that still have to be processed by the algorithm
List<BasicBlock> basicBlocksToProcess = new List<BasicBlock>(methodCfg.basicBlocks);
basicBlocksToProcess.Remove(startBasicBlock);
System.Console.WriteLine("Basic Blocks to process (Metadata): " + basicBlocksToProcess.Count());
// add metadata to all basic blocks
while (true) {
List<BasicBlock> copiedList = new List<BasicBlock>(basicBlocksToProcess);
foreach (BasicBlock currentBasicBlock in copiedList) {
// check if the current basic block was already visited => it is already used for the graph obfuscation => skip it
bool hasGraphMetadata = false;
for (int i = 0; i < currentBasicBlock.transformationMetadata.Count(); i++) {
// get graph transformer metadata for basic blocks
if ((currentBasicBlock.transformationMetadata.ElementAt(i) as IGraphTransformerMetadata) == null) {
continue;
}
hasGraphMetadata = true;
break;
}
if (hasGraphMetadata) {
basicBlocksToProcess.Remove(currentBasicBlock);
continue;
}
if (!this.createAndAddMetadata(currentBasicBlock)) {
continue;
}
// remove current basic block from the list of basic blocks to process
basicBlocksToProcess.Remove(currentBasicBlock);
}
System.Console.WriteLine("Basic Blocks to process (Metadata): " + basicBlocksToProcess.Count());
// check if basic blocks exist to process => if not break loop
if (basicBlocksToProcess.Count() == 0) {
break;
}
}
}
// this functions creates metadata for the given basic block and adds it
private bool createAndAddMetadata(BasicBlock currentBasicBlock) {
// get metadata of entry basic block (if exists)
IGraphTransformerMetadata previousMetadata = null;
BasicBlock previousBasicBlock = null;
IBranchTarget previousExitBranch = null;
for (int i = 0; i < currentBasicBlock.entryBranches.Count(); i++) {
previousBasicBlock = currentBasicBlock.entryBranches.ElementAt(i).sourceBasicBlock;
for (int j = 0; j < previousBasicBlock.transformationMetadata.Count(); j++) {
// get graph transformer metadata for basic blocks
if ((previousBasicBlock.transformationMetadata.ElementAt(j) as IGraphTransformerMetadata) == null) {
continue;
}
previousMetadata = (previousBasicBlock.transformationMetadata.ElementAt(j) as IGraphTransformerMetadata);
previousExitBranch = currentBasicBlock.entryBranches.ElementAt(i);
break;
}
if (previousMetadata != null) {
break;
}
}
// skip basic block if there is no metadata in one of the entry basic blocks
if (previousMetadata == null) { // TODO: here is room for optimization => do not skip it
return false;
}
List<BasicBlockGraphNodeLink> previousLinks = previousMetadata.correspondingGraphNodes;
// choose the next nodes of the obfuscation graph for the current basic block
NodeObject[] currentNodes = new NodeObject[this.graph.graphValidPathCount];
// check if previous basic block has links to the obfuscation graph for all existing valid paths
// (if previous basic block for example was a "state change" basic block it can only have one link to the obfuscation graph)
// => just copy obfuscation graph nodes of previous basic block if it contains all valid paths
if (previousLinks.Count() == this.graph.graphValidPathCount) {
for (int currentValidPathId = 0; currentValidPathId < this.graph.graphValidPathCount; currentValidPathId++) {
bool found = false;
for (int i = 0; i < previousLinks.Count(); i++) {
if (previousLinks.ElementAt(i).validPathId == currentValidPathId) {
currentNodes[currentValidPathId] = previousLinks.ElementAt(i).graphNode;
found = true;
break;
}
}
if (!found) {
throw new ArgumentException("Was not able to find link to obfuscation graph in previous basic block for at least one valid path.");
}
}
}
// previous basic block does not contain all valid paths
// => copy all existing valid paths links and choose random links for the missing ones
else {
for (int currentValidPathId = 0; currentValidPathId < this.graph.graphValidPathCount; currentValidPathId++) {
bool found = false;
for (int i = 0; i < previousLinks.Count(); i++) {
if (previousLinks.ElementAt(i).validPathId == currentValidPathId) {
currentNodes[currentValidPathId] = previousLinks.ElementAt(i).graphNode;
found = true;
break;
}
}
// if a link for the current valid path does not exist
// => choose randomly a node in the obfuscation graph on the current valid path
if (!found) {
int moveCount = this.prng.Next(this.graphDepth);
NodeObject nextNode = this.graph.startingNode;
for (int move = 0; move < moveCount; move++) {
for (int i = 0; i < nextNode.nodeObjects.Count(); i++) {
// if the child node does not belong to a valid path
// => skip it
if (nextNode.nodeObjects[i].elementOfValidPath.Count() == 0) {
continue;
}
// the child node belongs to a valid path
// => check if it is the correct valid path
else {
// if the child node belongs to the correct valid path
// => set next node to it
if (nextNode.nodeObjects[i].elementOfValidPath.Contains(currentValidPathId)) {
nextNode = nextNode.nodeObjects[i];
break;
}
}
}
if (nextNode == null) {
throw new ArgumentException("Not able to find correct child node.");
}
}
currentNodes[currentValidPathId] = nextNode;
}
}
}
NodeObject[] nextNodes = new NodeObject[this.graph.graphValidPathCount];
for (int currentValidPathId = 0; currentValidPathId < currentNodes.Count(); currentValidPathId++) {
// choose randomly if the pointer of the current valid path should be moved forward
// => move the pointer of the current valid path forward
if (this.prng.Next(2) == 0) {
// get the next node of the valid path
NodeObject nextNode = null;
int nextNodeIdx = 0;
this.getNextNode(ref nextNode, ref nextNodeIdx, currentNodes, currentValidPathId);
nextNodes[currentValidPathId] = nextNode;
}
// => do not move the pointer of the current valid path forward
else {
// set next node in the graph to the current one (it was not changed)
nextNodes[currentValidPathId] = currentNodes[currentValidPathId];
}
}
// create transformation metadata for the current basic block
GraphTransformerMetadataBasicBlock metadata = new GraphTransformerMetadataBasicBlock();
for (int currentValidPathId = 0; currentValidPathId < this.graph.graphValidPathCount; currentValidPathId++) {
BasicBlockGraphNodeLink link = new BasicBlockGraphNodeLink(nextNodes[currentValidPathId], currentValidPathId);
metadata.correspondingGraphNodes.Add(link);
}
currentBasicBlock.transformationMetadata.Add(metadata);
return true;
}
