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Core module of the project. It include all the SpotBugs detectors. The resulting jar is the published plugin.

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/**
 * Find Security Bugs
 * Copyright (c) Philippe Arteau, All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3.0 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.
 */
package com.h3xstream.findsecbugs.taintanalysis;

import com.h3xstream.findsecbugs.BCELUtil;
import com.h3xstream.findsecbugs.FindSecBugsGlobalConfig;
import com.h3xstream.findsecbugs.common.ByteCode;
import com.h3xstream.findsecbugs.taintanalysis.data.TaintLocation;
import com.h3xstream.findsecbugs.taintanalysis.data.UnknownSource;
import com.h3xstream.findsecbugs.taintanalysis.data.UnknownSourceType;
import edu.umd.cs.findbugs.ba.AbstractFrameModelingVisitor;
import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
import edu.umd.cs.findbugs.ba.InvalidBytecodeException;
import edu.umd.cs.findbugs.ba.generic.GenericSignatureParser;
import edu.umd.cs.findbugs.classfile.MethodDescriptor;
import edu.umd.cs.findbugs.util.ClassName;

import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.apache.bcel.Const;
import org.apache.bcel.generic.*;

/**
 * Visitor to make instruction transfer of taint values easier
 *
 * @author David Formanek (Y Soft Corporation, a.s.)
 */
public class TaintFrameModelingVisitor extends AbstractFrameModelingVisitor {

    private static final Logger LOG = Logger.getLogger(TaintFrameModelingVisitor.class.getName());

    private static final Map REPLACE_TAGS;
    private final MethodDescriptor methodDescriptor;
    private final TaintConfig taintConfig;
    private final TaintMethodConfig analyzedMethodConfig;

    private final List visitors;
    private final MethodGen methodGen;
    private String regexValue;

    static {
        REPLACE_TAGS = new HashMap();
        REPLACE_TAGS.put("\r", Taint.Tag.CR_ENCODED);
        REPLACE_TAGS.put("\n", Taint.Tag.LF_ENCODED);
        REPLACE_TAGS.put("\"", Taint.Tag.QUOTE_ENCODED);
        REPLACE_TAGS.put("'", Taint.Tag.APOSTROPHE_ENCODED);
        REPLACE_TAGS.put("<", Taint.Tag.LT_ENCODED);
    }

    /**
     * Constructs the object and stores the parameters
     * 
     * @param cpg constant pool gen for super class
     * @param method descriptor of analysed method
     * @param taintConfig current configured and derived taint summaries
     * @throws NullPointerException if arguments method or taintConfig is null
     */
    public TaintFrameModelingVisitor(ConstantPoolGen cpg, MethodDescriptor method,
            TaintConfig taintConfig, List visitors,MethodGen methodGen) {
        super(cpg);
        if (method == null) {
            throw new NullPointerException("null method descriptor");
        }
        if (taintConfig == null) {
            throw new NullPointerException("null taint config");
        }
        this.methodDescriptor = method;
        this.taintConfig = taintConfig;
        this.analyzedMethodConfig = new TaintMethodConfig(false);
        analyzedMethodConfig.setTypeSignature(methodDescriptor.getClassDescriptor().getClassName() + "." + methodDescriptor.getName() + methodDescriptor.getSignature());
        this.visitors = visitors;
        this.methodGen = methodGen;
    }

    private Collection getMutableStackIndices(String signature) {
        assert signature != null && !signature.isEmpty();
        ArrayList indices = new ArrayList();
        int stackIndex = 0;
        GenericSignatureParser parser = new GenericSignatureParser(signature);
        Iterator iterator = parser.parameterSignatureIterator();
        while (iterator.hasNext()) {
            String parameter = iterator.next();
            if ((parameter.startsWith("L") || parameter.startsWith("["))
                    && !taintConfig.isClassImmutable(parameter)) {
                indices.add(stackIndex);
            }
            if (parameter.equals("D") || parameter.equals("J")) {
                // double and long types takes two slots
                stackIndex += 2;
            } else {
                stackIndex++;
            }
        }
        for (int i = 0; i < indices.size(); i++) {
            int reverseIndex = stackIndex - indices.get(i) - 1;
            assert reverseIndex >= 0;
            indices.set(i, reverseIndex);
        }
        return indices;
    }

    @Override
    public void analyzeInstruction(Instruction ins) throws DataflowAnalysisException {
        //Print the bytecode instruction if it is globally configured
        if (FindSecBugsGlobalConfig.getInstance().isDebugPrintInvocationVisited()
                && ins instanceof InvokeInstruction) {
            //System.out.println(getFrame().toString());
            ByteCode.printOpCode(ins, cpg);
        } else if (FindSecBugsGlobalConfig.getInstance().isDebugPrintInstructionVisited()) {
            ByteCode.printOpCode(ins, cpg);
        }
        super.analyzeInstruction(ins);
    }

    @Override
    public Taint getDefaultValue() {
        return new Taint(Taint.State.UNKNOWN);
    }

    @Override
    public void visitLDC(LDC ldc) {
        Taint taint = new Taint(Taint.State.SAFE);
        Object value = ldc.getValue(cpg);
        if (value instanceof String) {
            taint.setConstantValue((String) value);
        }
        if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
            if (value instanceof String) {
                taint.setDebugInfo("\"" + value + "\"");
            } else {
                taint.setDebugInfo("LDC " + ldc.getType(cpg).getSignature());
            }
        }
        getFrame().pushValue(taint);
    }

    @Override
    public void visitLDC2_W(LDC2_W obj) {
        // double and long type takes two slots in BCEL
        if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
            pushSafeDebug("partial long/double");
            pushSafeDebug("partial long/double");
        } else {
            pushSafe();
            pushSafe();
        }
    }

    @Override
    public void visitBIPUSH(BIPUSH obj) {
        Taint taint = new Taint(Taint.State.SAFE);
        // assume each pushed byte is a char
        taint.setConstantValue(String.valueOf((char) obj.getValue().byteValue()));
        getFrame().pushValue(taint);
    }
    
    @Override
    public void visitSIPUSH(SIPUSH obj) {
        Taint taint = new Taint(Taint.State.SAFE);
        // assume each pushed short is a char (for non-ASCII characters)
        taint.setConstantValue(String.valueOf((char) obj.getValue().shortValue()));
        getFrame().pushValue(taint);
    }

    @Override
    public void visitGETSTATIC(GETSTATIC obj) {
        // Scala uses some classes to represent null instances of objects
        // If we find one of them, we will handle it as a Java Null
        if (obj.getLoadClassType(getCPG()).getSignature().equals("Lscala/collection/immutable/Nil$;")) {

            if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
                getFrame().pushValue(new Taint(Taint.State.NULL).setDebugInfo("NULL"));
            } else {
                getFrame().pushValue(new Taint(Taint.State.NULL));
            }
        } else {
            Taint taint;

            String fieldSig = BCELUtil.getSlashedClassName(cpg, obj)+"."+obj.getName(cpg);
            Taint.State state = taintConfig.getFieldTaintState(fieldSig, Taint.State.INVALID);
            if (state == Taint.State.INVALID) {
                state = taintConfig.getClassTaintState(obj.getSignature(cpg), Taint.State.INVALID);
            }
            if (state == Taint.State.INVALID) {
                taint = taintConfig.getStaticFieldTaint(fieldSig, getDefaultValue());
            }
            else {
                taint = new Taint(state);
            }

            if (!state.equals(Taint.State.SAFE)){
                taint.addLocation(getTaintLocation(), false);
            }
            taint.addSource(new UnknownSource(UnknownSourceType.FIELD,state).setSignatureField(fieldSig));

            int numConsumed = getNumWordsConsumed(obj);
            int numProduced = getNumWordsProduced(obj);
            modelInstruction(obj, numConsumed, numProduced, taint);

            notifyAdditionalVisitorField(obj, methodGen, getFrame(), taint, numProduced);
        }
    }

    @Override
    public void visitACONST_NULL(ACONST_NULL obj) {
        if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
            getFrame().pushValue(new Taint(Taint.State.NULL).setDebugInfo("NULL"));
        } else {
            getFrame().pushValue(new Taint(Taint.State.NULL));
        }
    }

    @Override
     public void visitICONST(ICONST obj) {
        Taint t = new Taint(Taint.State.SAFE);
        if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
            t.setDebugInfo("" + obj.getValue().intValue());
        }
        getFrame().pushValue(t);
    }

    @Override
    public void visitGETFIELD(GETFIELD obj) {
        String fieldSig = BCELUtil.getSlashedClassName(cpg, obj)+"."+obj.getName(cpg);
        Taint.State state = taintConfig.getFieldTaintState(fieldSig, Taint.State.INVALID);
        if (state == Taint.State.INVALID) {
            state = taintConfig.getClassTaintState(obj.getSignature(cpg), Taint.State.INVALID);
        }
        if (state == Taint.State.INVALID) {
            state = Taint.State.UNKNOWN;
        }

        Taint taint = new Taint(state);

        if (!state.equals(Taint.State.SAFE)){
            taint.addLocation(getTaintLocation(), false);
        }
        taint.addSource(new UnknownSource(UnknownSourceType.FIELD,state).setSignatureField(fieldSig));
        if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
            taint.setDebugInfo("." + obj.getFieldName(cpg));
        }
        int numConsumed = getNumWordsConsumed(obj);
        int numProduced = getNumWordsProduced(obj);
        modelInstruction(obj, numConsumed, numProduced, taint);


        notifyAdditionalVisitorField(obj, methodGen, getFrame(), taint, numProduced);
    }

    @Override
    public void visitPUTFIELD(PUTFIELD obj) {
        visitPutFieldOp(obj);
    }

    @Override
    public void visitPUTSTATIC(PUTSTATIC obj) {
        try {
            String fieldSig = BCELUtil.getSlashedClassName(cpg, obj)+"."+obj.getName(cpg);
            Taint staticTaint = taintConfig.getStaticFieldTaint(fieldSig, null);
            Taint t = getFrame().getTopValue();
            t = Taint.merge(t, staticTaint);

            // we are escaping a method context into a global class context
            // method parameters and variables make no sense there
            // 1. clear any method parameters
            t.clearParameters();
            // 2. clear method variable indexes
            t.invalidateVariableIndex();

            taintConfig.putStaticFieldTaint(fieldSig, t);
        } catch (DataflowAnalysisException e) {
        }

        visitPutFieldOp(obj);
    }

    public void visitPutFieldOp(FieldInstruction obj) {

        //int numConsumed = getNumWordsConsumed(obj);
        int numProduced = getNumWordsProduced(obj);
        try {
            Taint t = getFrame().getTopValue();
            handleNormalInstruction(obj);
            notifyAdditionalVisitorField(obj, methodGen, getFrame(), t, numProduced);
        } catch (DataflowAnalysisException e) {

        }

    }

    private void notifyAdditionalVisitorField(FieldInstruction instruction, MethodGen methodGen, TaintFrame frame,
                                              Taint taintValue, int numProduced) {
        for(TaintFrameAdditionalVisitor visitor : visitors) {
            try {
                visitor.visitField(instruction, methodGen, frame, taintValue, numProduced, cpg);
            }
            catch (Throwable e) {
                LOG.log(Level.SEVERE,"Error while executing "+visitor.getClass().getName(),e);
            }
        }
    }

    @Override
    public void visitNEW(NEW obj) {
        Taint taint = new Taint(Taint.State.SAFE);
        ObjectType type = obj.getLoadClassType(cpg);
        taint.setRealInstanceClass(type);
        if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
            taint.setDebugInfo("new " + type.getClassName() + "()");
        }
        getFrame().pushValue(taint);
    }

    @Override
    public void handleStoreInstruction(StoreInstruction obj) {
        try {
            int numConsumed = obj.consumeStack(cpg);
            if (numConsumed == Const.UNPREDICTABLE) {
                throw new InvalidBytecodeException("Unpredictable stack consumption");
            }
            int index = obj.getIndex();
            while (numConsumed-- > 0) {
                Taint value = new Taint(getFrame().popValue());
//                Taint value = getFrame().popValue();
                value.setVariableIndex(index);
                getFrame().setValue(index++, value);
            }
        } catch (DataflowAnalysisException ex) {
            throw new InvalidBytecodeException(ex.toString(), ex);
        }
    }

    @Override
    public void handleLoadInstruction(LoadInstruction load) {
        int numProducedOrig = load.produceStack(cpg);
        int numProduced = numProducedOrig;
        if (numProduced == Const.UNPREDICTABLE) {
            throw new InvalidBytecodeException("Unpredictable stack production");
        }
        int index = load.getIndex() + numProduced;
        while (numProduced-- > 0) {
            Taint value = getFrame().getValue(--index);
            //assert value.hasValidVariableIndex() :
            if(!value.hasValidVariableIndex()) {
                throw new RuntimeException("index not set in " + methodDescriptor);
            }
            if(index != value.getVariableIndex()) {
                throw new RuntimeException("bad index in " + methodDescriptor);
            }
//            getFrame().pushValue(new Taint(value));
            getFrame().pushValue(value);
        }

        for(TaintFrameAdditionalVisitor visitor : visitors) {
            try {
                visitor.visitLoad(load, methodGen, getFrame(), numProducedOrig, cpg);
            }
            catch (Throwable e) {
                LOG.log(Level.SEVERE,"Error while executing "+visitor.getClass().getName(),e);
            }
        }
    }

    @Override
    public void visitINVOKEINTERFACE(INVOKEINTERFACE obj) {
        visitInvoke(obj);
    }

    @Override
    public void visitINVOKESPECIAL(INVOKESPECIAL obj) {
        visitInvoke(obj);
    }

    @Override
    public void visitINVOKESTATIC(INVOKESTATIC obj) {
        visitInvoke(obj);
    }

    @Override
    public void visitINVOKEVIRTUAL(INVOKEVIRTUAL obj) {
        visitInvoke(obj);
    }

    @Override
    public void visitINVOKEDYNAMIC(INVOKEDYNAMIC obj) {
        if(FindSecBugsGlobalConfig.getInstance().isWorkaroundVisitInvokeDynamic()) {
            visitInvoke(obj);
        } else {
            handleNormalInstruction(obj);
        }
    }
    @Override
    public void visitANEWARRAY(ANEWARRAY obj) {
        try {
            getFrame().popValue();
            if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
                pushSafeDebug("new " + obj.getLoadClassType(cpg).getClassName() + "[]");
            } else {
                pushSafe();
            }
        } catch (DataflowAnalysisException ex) {
            throw new InvalidBytecodeException("Array length not in the stack", ex);
        }
    }

    @Override
    public void visitAASTORE(AASTORE obj) {
        try {
            Taint valueTaint = getFrame().popValue(); //Value
            getFrame().popValue(); //Array index
            Taint arrayTaint = getFrame().popValue(); //Array ref

            Taint merge = Taint.merge(valueTaint, arrayTaint);
            setLocalVariableTaint(merge, arrayTaint);
            Taint stackTop = null;
            if (getFrame().getStackDepth() > 0) {
                stackTop = getFrame().getTopValue();
            }
            // varargs use duplicated values
            if (arrayTaint.equals(stackTop)) {
                getFrame().popValue();
                getFrame().pushValue(new Taint(merge));
            }
        } catch (DataflowAnalysisException ex) {
            throw new InvalidBytecodeException("Not enough values on the stack", ex);
        }
    }

    @Override
    public void visitAALOAD(AALOAD obj) {
        try {
            getFrame().popValue(); // array index
            // just transfer the taint from array to value at any index
        } catch (DataflowAnalysisException ex) {
            throw new InvalidBytecodeException("Not enough values on the stack", ex);
        }
    }


    @Override
    public void visitCHECKCAST(CHECKCAST obj) {
        // cast to a safe object type
        ObjectType objectType = obj.getLoadClassType(cpg);
        if (objectType == null) {
            return;
        }

        String objectTypeSignature = objectType.getSignature();

        if(!taintConfig.isClassTaintSafe(objectTypeSignature)) {
            return;
        }

        try {
            getFrame().popValue();
            pushSafe();
        }
        catch (DataflowAnalysisException ex) {
            throw new InvalidBytecodeException("empty stack for checkcast", ex);
        }
    }

    @Override
    public void visitReturnInstruction(ReturnInstruction obj) {
        List parametersLocalValueIndexes = new ArrayList<>();

        GenericSignatureParser genericSignatureParser = new GenericSignatureParser(methodDescriptor.getSignature());
        int localValueIndex = 0;
        //  non-static methods have the class instance as the first index
        if (!methodDescriptor.isStatic()) {
            localValueIndex++;
        }
        for (Iterator it = genericSignatureParser.parameterSignatureIterator(); it.hasNext();) {
            String parameter = it.next();
            switch (parameter.charAt(0)) {
                case 'D':
                case 'J':
                    // double and long occupy two slots
                    localValueIndex++;
                    break;
                case '[':
                    // back-propagate array taints
                    parametersLocalValueIndexes.add(localValueIndex);
                    break;
                case 'L':
                    // back-propagate mutable class taints
                    if (!taintConfig.isClassImmutable(parameter)) {
                        parametersLocalValueIndexes.add(localValueIndex);
                    }
                    else {
                        // back-propage immutable taints only when they transfer tags
                        Taint taint = getFrame().getValue(localValueIndex);
                        if (taint.hasTags() || taint.isRemovingTags()) {
                            parametersLocalValueIndexes.add(localValueIndex);
                        }
                    }
                    break;
            }

            localValueIndex++;
        }

        int parametersCount = localValueIndex;

        for (int parameterLocalValueIndex : parametersLocalValueIndexes) {
            Taint parameterTaint = getFrame().getValue(parameterLocalValueIndex);
            int stackIndex = (parametersCount - 1) - parameterLocalValueIndex;

            if (!parameterTaint.isUnknown()) {
                analyzedMethodConfig.setParameterOutputTaint(stackIndex, parameterTaint);
            }
            else if (parameterTaint.getNonParametricState() != Taint.State.INVALID) {
                analyzedMethodConfig.setParameterOutputTaint(stackIndex, parameterTaint);
            }
            else if (parameterTaint.hasTags() || parameterTaint.isRemovingTags()) {
                analyzedMethodConfig.setParameterOutputTaint(stackIndex, parameterTaint);
            }
            else if (parameterTaint.getParameters().size() > 1) {
                analyzedMethodConfig.setParameterOutputTaint(stackIndex, parameterTaint);
            }
        }

        analyzedMethodConfig.setParametersOutputTaintsProcessed(true);

        super.visitReturnInstruction(obj);
    }

    @Override
    public void visitARETURN(ARETURN obj) {
        Taint returnTaint = null;
        try {
            returnTaint = getFrame().getTopValue();
            Taint currentTaint = analyzedMethodConfig.getOutputTaint();
            analyzedMethodConfig.setOuputTaint(Taint.merge(returnTaint, currentTaint));
        } catch (DataflowAnalysisException ex) {
            throw new InvalidBytecodeException("empty stack before reference return", ex);
        }
        handleNormalInstruction(obj);

        for(TaintFrameAdditionalVisitor visitor : visitors) {
            try {
                visitor.visitReturn(methodGen, returnTaint, cpg);
            }
            catch (Throwable e) {
                LOG.log(Level.SEVERE,"Error while executing "+visitor.getClass().getName(),e);
            }
        }
    }

    /**
     * Regroup the method invocations (INVOKEINTERFACE, INVOKESPECIAL,
     * INVOKESTATIC, INVOKEVIRTUAL)
     *
     * @param obj one of the invoke instructions
     */
    private void visitInvoke(InvokeInstruction obj) {
        assert obj != null;
        try {
            TaintMethodConfig methodConfig = getMethodConfig(obj);
            Taint taint = getMethodTaint(methodConfig);
            assert taint != null;
            if (FindSecBugsGlobalConfig.getInstance().isDebugTaintState()) {
                taint.setDebugInfo(obj.getMethodName(cpg) + "()"); //TODO: Deprecated debug info
            }
            taint.addSource(new UnknownSource(UnknownSourceType.RETURN,taint.getState()).setSignatureMethod(BCELUtil.getSlashedClassName(cpg, obj)+"."+obj.getMethodName(cpg)+obj.getSignature(cpg)));
            taintMutableArguments(methodConfig, obj);
            transferTaintToMutables(methodConfig, taint); // adds variable index to taint too
//            Taint taintCopy = new Taint(taint);
            Taint taintCopy = taint;
            // return type is not always the instance type
            taintCopy.setRealInstanceClass(methodConfig != null && methodConfig.getOutputTaint() != null ? methodConfig.getOutputTaint().getRealInstanceClass() : null);

            TaintFrame tf = getFrame();

            int stackDepth = tf.getStackDepth();
            int nbParam = getNumWordsConsumed(obj);
            List parameters = new ArrayList<>(nbParam);
            for(int i=0;i()V");
                return config;
            } catch (DataflowAnalysisException ex) {
                throw new InvalidBytecodeException(ex.getMessage(), ex);
            }
        }
        return null;
    }

    private TaintMethodConfig getConfigWithReplaceTags(TaintMethodConfig config, String className, String methodName) {

        ObjectConfiguration objectConfiguration = new ObjectConfiguration(className, methodName);

        if (!objectConfiguration.isAClassThatCanReplaceString()) {
            return config;
        }

        /*
          When Kotlin compiles the String replace method (when using regex values) Kotlin creates several instructions in its place.

          One of the instructions is to create an instance of the Regex class (using the regex String as a parameter). The Regex instance is then used as a parameter to the replace method.
          In order to have access to the regex value when the String replace method is called,
          we need to store the value at the first pass (when the Regex instance is created) and then use it when the replace method is called.

          The below if code is to identify when a Regex instance is being created and store the value, to retrieve on the next pass.

         */
        if (objectConfiguration.isKotlinRegexMethodAndConstructorMethod()) {
            saveRegexValueForNextInstruction();
            return config;
        }

        if (!objectConfiguration.isAReplaceMethod()) {
            return config;
        }

        try {
            String toReplace = objectConfiguration.getStringParameterForReplaceMethod();

            if (toReplace == null) {
                // we don't know the exact value
                return config;
            }

            Taint taint = config.getOutputTaint();

            for (Map.Entry replaceTag : REPLACE_TAGS.entrySet()) {
                String tagString = replaceTag.getKey();
                if ((objectConfiguration.isAReplaceMethodWithRegexParameter() && toReplace.contains(tagString))
                        || toReplace.equals(tagString)) {
                    taint.addTag(replaceTag.getValue());
                }
            }

            TaintMethodConfig configCopy = new TaintMethodConfig(config);
            configCopy.setOuputTaint(taint);
            return configCopy;
        } catch (DataflowAnalysisException ex) {
            throw new InvalidBytecodeException(ex.getMessage(), ex);
        }
    }

    private String getRegexValueFromAPreviousInstruction() {
        String tmp = regexValue;
        regexValue = null; // clean up regex value so other instructions after the current one can't use it.
        return tmp;
    }

    private void saveRegexValueForNextInstruction() {
        regexValue = getFrame().getValue(getFrame().getNumSlots() - 1).getConstantValue();
    }

    private String getInstanceClassName(InvokeInstruction invoke) {
        try {
            int instanceIndex = getFrame().getNumArgumentsIncludingObjectInstance(invoke, cpg) - 1;
            if (instanceIndex != -1) {
                assert instanceIndex < getFrame().getStackDepth();
                Taint instanceTaint = getFrame().getStackValue(instanceIndex);
                String className = instanceTaint.getRealInstanceClassName();
                if (className != null) {
                    return className;
                }
            }
        } catch (DataflowAnalysisException ex) {
            assert false : ex.getMessage();
        }
        return BCELUtil.getSlashedClassName(cpg, invoke);
    }

    private static String getReturnType(String signature) {
        assert signature != null && signature.contains(")");
        return signature.substring(signature.indexOf(')') + 1);
    }

    private Taint getMethodTaint(TaintMethodConfig methodConfig) {
        if (methodConfig == null || methodConfig.getOutputTaint() == null) {
            return getDefaultValue();
        }
        Taint outputTaint = methodConfig.getOutputTaint();
        assert outputTaint != null;
        assert outputTaint != methodConfig.getOutputTaint() : "defensive copy not made";

        Taint taint = mergeTaintWithStack(outputTaint);

        if (taint.isTainted()) {
            taint.addLocation(getTaintLocation(), true);
        }
        else if (taint.isUnknown()) {
            taint.addLocation(getTaintLocation(), false);
        }

        return taint;
    }

    private Taint mergeTaintWithStack(Taint taint) {
        assert taint != null;
        Taint result = taint;
        if (taint.isUnknown() && taint.hasParameters()) {
            // taint consisting of merged parameters only
            Taint transferParametersTaint = mergeTransferParameters(taint.getParameters());
            assert transferParametersTaint != null;

            if (taint.getNonParametricState() != Taint.State.INVALID) {
                // if the method body has own inner state then merge with parameters
                result = Taint.merge(Taint.valueOf(taint.getNonParametricState()), transferParametersTaint);
            }
            else {
                result = transferParametersTaint;
            }

            result.addAllSources(taint.getSources());

            // merge removes tags so we made a taint copy before
            for (TaintLocation unknownLocation : taint.getUnknownLocations()) {
                result.addLocation(unknownLocation, false);
            }
            for (TaintLocation taintLocation : taint.getTaintedLocations()) {
                result.addLocation(taintLocation, true);
            }

            // don't add tags to safe values
            if (!result.isSafe() && taint.hasTags()) {
                for (Taint.Tag tag : taint.getTags()) {
                    result.addTag(tag);
                }
            }
            if (taint.isRemovingTags()) {
                for (Taint.Tag tag : taint.getTagsToRemove()) {
                    result.removeTag(tag);
                }
            }
        }
        return result;
    }

    private void taintMutableArguments(TaintMethodConfig methodConfig, InvokeInstruction obj) {
        if (methodConfig != null && methodConfig.isConfigured()) {
            return;
        }

        if (methodConfig != null && methodConfig.isParametersOutputTaintsProcessed()) {
            for (Map.Entry entry : methodConfig.getParametersOutputTaints().entrySet()) {
                int stackIndex = entry.getKey();
                assert stackIndex >= 0 && stackIndex < getFrame().getStackDepth();

                Taint parameterTaint = entry.getValue();
                assert parameterTaint != null;

                try {
                    Taint taint = new Taint(parameterTaint);
                    taint = mergeTaintWithStack(taint);

                    Taint stackValue = getFrame().getStackValue(stackIndex);
                    if (stackValue.hasValidVariableIndex()) {
                        // set back the index removed during merging
                        taint.setVariableIndex(stackValue.getVariableIndex());
                    }
                    taint.setRealInstanceClass(stackValue.getRealInstanceClass());
                    getFrame().setValue(getFrame().getStackLocation(stackIndex), taint);
                    setLocalVariableTaint(taint, stackValue);
                }
                catch (DataflowAnalysisException ex) {
                    throw new InvalidBytecodeException("Not enough values on the stack", ex);
                }
            }

            return;
        }

        Collection mutableStackIndices = getMutableStackIndices(obj.getSignature(cpg));
        for (Integer index : mutableStackIndices) {
            assert index >= 0 && index < getFrame().getStackDepth();
            try {
                Taint stackValue = getFrame().getStackValue(index);
                Taint taint = Taint.merge(stackValue, getDefaultValue());
                if (stackValue.hasValidVariableIndex()) {
                    // set back the index removed during merging
                    taint.setVariableIndex(stackValue.getVariableIndex());
                }
                taint.setRealInstanceClass(stackValue.getRealInstanceClass());
                taint.addLocation(getTaintLocation(), false);
                getFrame().setValue(getFrame().getStackLocation(index), taint);
                setLocalVariableTaint(taint, taint);
            } catch (DataflowAnalysisException ex) {
                throw new InvalidBytecodeException("Not enough values on the stack", ex);
            }
        }
    }

    private Taint mergeTransferParameters(Collection transferParameters) {
        assert transferParameters != null && !transferParameters.isEmpty();
        Taint taint = null;
        Taint safeTaint = null;
        for (Integer transferParameter : transferParameters) {
            try {
                Taint value = getFrame().getStackValue(transferParameter);
                if (value.isSafe()) {
                    safeTaint = Taint.merge(safeTaint, value);;
                } else {
                    taint = Taint.merge(taint, value);
                }
            } catch (DataflowAnalysisException ex) {
                throw new RuntimeException("Bad transfer parameter specification", ex);
            }
        }
        assert taint != null || safeTaint != null;
        if (taint == null) {
            return safeTaint;
        }
        return taint;
    }

    private void transferTaintToMutables(TaintMethodConfig methodConfig, Taint taint) {
        assert taint != null;
        if (methodConfig == null || !methodConfig.hasMutableStackIndices()) {
            return;
        }
        try {
            int stackDepth = getFrame().getStackDepth();
            for (Integer mutableStackIndex : methodConfig.getMutableStackIndices()) {
                assert mutableStackIndex >= 0;
                if (mutableStackIndex >= stackDepth) {
                    if (!Const.CONSTRUCTOR_NAME.equals(methodDescriptor.getName())
                            && !Const.STATIC_INITIALIZER_NAME.equals(methodDescriptor.getName())) {
                        assert false : "Out of bounds mutables in " + methodDescriptor + " Method Config: " + methodConfig.toString();
                    }
                    continue; // ignore if assertions disabled or if in constructor
                }
                Taint stackValue = getFrame().getStackValue(mutableStackIndex);
                setLocalVariableTaint(taint, stackValue);
                Taint taintCopy = new Taint(taint);
                // do not set instance to return values, can be different type
                taintCopy.setRealInstanceClass(stackValue.getRealInstanceClass());
                getFrame().setValue(getFrame().getStackLocation(mutableStackIndex), taintCopy);
            }
        } catch (DataflowAnalysisException ex) {
            assert false : ex.getMessage(); // stack depth is checked
        }
    }

    private void setLocalVariableTaint(Taint valueTaint, Taint indexTaint) {
        assert valueTaint != null && indexTaint != null;
        if (!indexTaint.hasValidVariableIndex()) {
            return;
        }
        int index = indexTaint.getVariableIndex();
        if (index >= getFrame().getNumLocals()) {
            assert false : "Out of bounds local variable index in " + methodDescriptor;
            return; // ignore if assertions disabled
        }

        if (valueTaint.hasValidVariableIndex() && valueTaint.getVariableIndex() != index) {
            valueTaint = new Taint(valueTaint);
        }

        valueTaint.setVariableIndex(index);
        getFrame().setValue(index, valueTaint);
    }

    /**
     * Push a value to the stack
     */
    private void pushSafe() {
        getFrame().pushValue(new Taint(Taint.State.SAFE));
    }

    /**
     * Push a value to the stack
     * The information passed will be viewable when the stack will be print. (See printStackState())
     * @param debugInfo String representation of the value push
     */
    private void pushSafeDebug(String debugInfo) {
        getFrame().pushValue(new Taint(Taint.State.SAFE).setDebugInfo(debugInfo));
    }

    private TaintLocation getTaintLocation() {
        return new TaintLocation(methodDescriptor, getLocation().getHandle().getPosition());
    }

    /**
     * This method must be called from outside at the end of the method analysis
     */
    public void finishAnalysis() {
        assert analyzedMethodConfig != null;
        Taint outputTaint = analyzedMethodConfig.getOutputTaint();
        if (outputTaint != null) {
            String returnType = getReturnType(methodDescriptor.getSignature());
            String realInstanceClassName = outputTaint.getRealInstanceClassName();
            if (returnType.equals("L" + realInstanceClassName + ";")) {
                // storing it in method summary is useless
                outputTaint.setRealInstanceClass(null);
                analyzedMethodConfig.setOuputTaint(outputTaint);
            }
        }
        String className = methodDescriptor.getSlashedClassName();
        String methodId = "." + methodDescriptor.getName() + methodDescriptor.getSignature();
        if (analyzedMethodConfig.isInformative()
                || taintConfig.getSuperMethodConfig(className, methodId) != null) {
            String fullMethodName = className.concat(methodId);
            if (!taintConfig.containsKey(fullMethodName)) {
                // prefer configured summaries to derived
                taintConfig.put(fullMethodName, analyzedMethodConfig);
            }
        }
    }

    private class ObjectConfiguration {

        private static final int JAVA_STRING_PARAMETER_INDEX = 1;
        private static final int KOTLIN_STRING_PARAMETER_INDEX = 4;

        private final String className;
        private final String methodName;

        private ObjectConfiguration(String className, String methodName) {
            this.className = className;
            this.methodName = methodName;
        }

        private boolean isJavaString() {
            return "java/lang/String".equals(className);
        }

        private boolean isKotlinString() {
            return "kotlin/text/StringsKt".equals(className);
        }

        private boolean isKotlinRegex() {
            return "kotlin/text/Regex".equals(className);
        }

        private boolean isConstructor() {
            return Const.CONSTRUCTOR_NAME.equals(methodName);
        }

        private boolean isKotlinRegexMethodAndConstructorMethod() {
            return isKotlinRegex() && isConstructor();
        }

        private boolean isJavaStringWithSimpleReplace() {
            return isJavaString() && "replace".equals(methodName);
        }

        private boolean isKotlinStringWithSimpleReplace() {
            return isKotlinString() && "replace$default".equals(methodName);
        }

        private boolean isJavaStringWithRegexReplace() {
            return isJavaString() && "replaceAll".equals(methodName);
        }

        private boolean isKotlinRegexWithReplace() {
            return isKotlinRegex() && "replace".equals(methodName);
        }

        private boolean isAClassThatCanReplaceString() {
            return isJavaString() || isKotlinString() || isKotlinRegex();
        }

        private boolean isAReplaceMethod() {
            return isJavaStringWithRegexReplace() || isKotlinRegexWithReplace() || isJavaStringWithSimpleReplace() || isKotlinStringWithSimpleReplace();
        }

        private boolean isAReplaceMethodWithRegexParameter() {
            return isJavaStringWithRegexReplace() || isKotlinRegexWithReplace();
        }

        private String getStringParameterForReplaceMethod() throws DataflowAnalysisException {

            if (isJavaString()) {
                return getFrame().getStackValue(JAVA_STRING_PARAMETER_INDEX).getConstantValue();
            } else if (isKotlinString()) {
                return getFrame().getStackValue(KOTLIN_STRING_PARAMETER_INDEX).getConstantValue();
            } else if (isKotlinRegexWithReplace()) {
                return getRegexValueFromAPreviousInstruction();
            }

            return null;
        }
    }

}




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