Ghidra script to cluster functions by their function ID, applying tags to functions in clusters of size >1. Helps identify functions that have identical or very similar behaviour.

ClusterFunctionsByFID.java

// Clusters functions by their function ID and applies tags to functions in clusters with a size larger than 1.
//@category FunctionID
//@author Graham Sutherland

import java.io.IOException;
import java.util.*;

import ghidra.app.script.GhidraScript;
import ghidra.feature.fid.hash.FidHashQuad;
import ghidra.feature.fid.plugin.HashLookupListMode;
import ghidra.feature.fid.service.FidService;
import ghidra.framework.model.DomainFile;
import ghidra.framework.model.DomainFolder;
import ghidra.program.database.ProgramContentHandler;
import ghidra.program.model.listing.*;
import ghidra.util.Msg;
import ghidra.util.NumericUtilities;
import ghidra.util.exception.CancelledException;
import ghidra.util.exception.VersionException;

public class ClusterFunctionsByFID extends GhidraScript
{
	FidService service;

	@Override
	protected void run() throws Exception
	{
		println("Finding hashes...");
		service = new FidService();
		FunctionManager functionManager = currentProgram.getFunctionManager();
		FunctionIterator functions = functionManager.getFunctions(true);
		Map<Long, ArrayList<Function>> fbh = new HashMap<Long, ArrayList<Function>>();
		for (Function function : functions)
		{
			if (monitor.isCancelled())
			{
				return;
			}
			FidHashQuad hashQuad = service.hashFunction(function);
			if (hashQuad == null)
			{
				continue;
			}
			long hash = hashQuad.getFullHash();
			fbh.putIfAbsent(hash, new ArrayList<Function>());
			fbh.get(hash).add(function);
		}
		for (Map.Entry<Long, ArrayList<Function>> entry : fbh.entrySet())
		{
			ArrayList<Function> cluster = entry.getValue();
			if (cluster.size() > 1)
			{
				// List<String> functionNames = new List<String>();
				printf("%x", entry.getKey());
				print(": ");
				for (int i = 0; i < cluster.size(); i++)
				{
					Function f = cluster.get(i);
					print(f.getName() + " ");
					f.addTag("fid_" + Long.toHexString(entry.getKey()));
				}
				print("\n");
			}
		}
	}
}