Examples with BitVecExpr com.microsoft.z3.BitVecExpr used on opensource projects

Example 11 with BitVecExpr

use of com.microsoft.z3.BitVecExpr in project batfish by batfish.

the class EncoderSlice method firstBitsEqual.

private BoolExpr firstBitsEqual(BitVecExpr x, long y, int n) {
    assert (n >= 0 && n <= 32);
    if (n == 0) {
        return mkTrue();
    }
    int m = 0;
    for (int i = 0; i < n; i++) {
        m |= (1 << (31 - i));
    }
    BitVecExpr mask = getCtx().mkBV(m, 32);
    BitVecExpr val = getCtx().mkBV(y, 32);
    return mkEq(getCtx().mkBVAND(x, mask), getCtx().mkBVAND(val, mask));
}

Example 12 with BitVecExpr

use of com.microsoft.z3.BitVecExpr in project batfish by batfish.

the class PropertyAdder method instrumentLoad.

/*
   * Instruments the network with load balancing information to destination
   * port for graph edge ge. Each router will split load according to the
   * number of neighbors it actively uses to get to ge.
   */
Map<String, ArithExpr> instrumentLoad(Set<GraphEdge> ges) {
    Context ctx = _encoderSlice.getCtx();
    Solver solver = _encoderSlice.getSolver();
    String sliceName = _encoderSlice.getSliceName();
    Map<String, ArithExpr> loadVars = new HashMap<>();
    Graph graph = _encoderSlice.getGraph();
    for (String router : graph.getRouters()) {
        String name = _encoderSlice.getEncoder().getId() + "_" + sliceName + "_load_" + router;
        ArithExpr var = ctx.mkIntConst(name);
        loadVars.put(router, var);
        _encoderSlice.getAllVariables().put(var.toString(), var);
    }
    loadVars.forEach((name, var) -> solver.add(ctx.mkGe(var, ctx.mkInt(0))));
    ArithExpr zero = ctx.mkInt(0);
    ArithExpr one = ctx.mkInt(1);
    for (Entry<String, List<GraphEdge>> entry : graph.getEdgeMap().entrySet()) {
        String router = entry.getKey();
        List<GraphEdge> edges = entry.getValue();
        ArithExpr load = loadVars.get(router);
        BoolExpr hasDirectRoute = ctx.mkFalse();
        BoolExpr isAbsorbed = ctx.mkFalse();
        SymbolicRoute r = _encoderSlice.getBestNeighborPerProtocol(router, Protocol.CONNECTED);
        for (GraphEdge ge : edges) {
            if (!ge.isAbstract() && ges.contains(ge)) {
                // if we leave the network
                if (ge.getPeer() == null) {
                    BoolExpr fwdIface = _encoderSlice.getForwardsAcross().get(ge.getRouter(), ge);
                    assert (fwdIface != null);
                    hasDirectRoute = ctx.mkOr(hasDirectRoute, fwdIface);
                }
                // if connected route and we use it despite not forwarding
                if (r != null) {
                    BitVecExpr dstIp = _encoderSlice.getSymbolicPacket().getDstIp();
                    BitVecExpr ip = ctx.mkBV(ge.getStart().getAddress().getIp().asLong(), 32);
                    BoolExpr reach = ctx.mkAnd(r.getPermitted(), ctx.mkEq(dstIp, ip));
                    isAbsorbed = ctx.mkOr(isAbsorbed, reach);
                }
            }
        }
        ArithExpr acc = ctx.mkInt(0);
        for (GraphEdge edge : edges) {
            if (!edge.isAbstract()) {
                BoolExpr fwd = _encoderSlice.getForwardsAcross().get(router, edge);
                assert (fwd != null);
                if (edge.getPeer() != null) {
                    ArithExpr peerLoad = loadVars.get(edge.getPeer());
                    ArithExpr x = (ArithExpr) ctx.mkITE(fwd, peerLoad, zero);
                    acc = ctx.mkAdd(acc, x);
                }
            }
        }
        solver.add(ctx.mkEq(load, acc));
        BoolExpr guard = _encoderSlice.mkOr(hasDirectRoute, isAbsorbed);
        BoolExpr cond = _encoderSlice.mkIf(guard, ctx.mkEq(load, one), ctx.mkEq(load, acc));
        solver.add(cond);
    }
    return loadVars;
}

Example 13 with BitVecExpr

use of com.microsoft.z3.BitVecExpr in project batfish by batfish.

the class TransferSSA method compute.

/*
   * Convert a list of statements into a Z3 boolean expression for the transfer function.
   */
private TransferResult<BoolExpr, BoolExpr> compute(List<Statement> statements, TransferParam<SymbolicRoute> p, TransferResult<BoolExpr, BoolExpr> result) {
    boolean doesReturn = false;
    for (Statement stmt : statements) {
        if (stmt instanceof StaticStatement) {
            StaticStatement ss = (StaticStatement) stmt;
            switch(ss.getType()) {
                case ExitAccept:
                    doesReturn = true;
                    p.debug("ExitAccept");
                    result = returnValue(p, result, true);
                    break;
                case ReturnTrue:
                    doesReturn = true;
                    p.debug("ReturnTrue");
                    result = returnValue(p, result, true);
                    break;
                case ExitReject:
                    doesReturn = true;
                    p.debug("ExitReject");
                    result = returnValue(p, result, false);
                    break;
                case ReturnFalse:
                    doesReturn = true;
                    p.debug("ReturnFalse");
                    result = returnValue(p, result, false);
                    break;
                case SetDefaultActionAccept:
                    p.debug("SetDefaulActionAccept");
                    p = p.setDefaultAccept(true);
                    break;
                case SetDefaultActionReject:
                    p.debug("SetDefaultActionReject");
                    p = p.setDefaultAccept(false);
                    break;
                case SetLocalDefaultActionAccept:
                    p.debug("SetLocalDefaultActionAccept");
                    p = p.setDefaultAcceptLocal(true);
                    break;
                case SetLocalDefaultActionReject:
                    p.debug("SetLocalDefaultActionReject");
                    p = p.setDefaultAcceptLocal(false);
                    break;
                case ReturnLocalDefaultAction:
                    p.debug("ReturnLocalDefaultAction");
                    // TODO: need to set local default action in an environment
                    if (p.getDefaultAcceptLocal()) {
                        result = returnValue(p, result, true);
                    } else {
                        result = returnValue(p, result, false);
                    }
                    break;
                case FallThrough:
                    p.debug("Fallthrough");
                    result = fallthrough(p, result);
                    break;
                case Return:
                    // TODO: assumming this happens at the end of the function, so it is ignored for now.
                    p.debug("Return");
                    break;
                case RemovePrivateAs:
                    p.debug("RemovePrivateAs");
                    System.out.println("Warning: use of unimplemented feature RemovePrivateAs");
                    break;
                default:
                    throw new BatfishException("TODO: computeTransferFunction: " + ss.getType());
            }
        } else if (stmt instanceof If) {
            p.debug("If");
            If i = (If) stmt;
            TransferResult<BoolExpr, BoolExpr> r = compute(i.getGuard(), p);
            result = result.addChangedVariables(r);
            BoolExpr guard = (BoolExpr) r.getReturnValue().simplify();
            String str = guard.toString();
            // If there are updates in the guard, add them to the parameter p before entering branches
            for (Pair<String, Expr> changed : r.getChangedVariables()) {
                p.debug("CHANGED: " + changed.getFirst());
                updateSingleValue(p, changed.getFirst(), changed.getSecond());
            }
            p.debug("guard: " + str);
            // If we know the branch ahead of time, then specialize
            switch(str) {
                case "true":
                    p.debug("True Branch");
                    result = compute(i.getTrueStatements(), p.indent(), result);
                    break;
                case "false":
                    p.debug("False Branch");
                    compute(i.getFalseStatements(), p.indent(), result);
                    break;
                default:
                    p.debug("True Branch");
                    // clear changed variables before proceeding
                    TransferParam<SymbolicRoute> p1 = p.indent().setData(p.getData().copy());
                    TransferParam<SymbolicRoute> p2 = p.indent().setData(p.getData().copy());
                    TransferResult<BoolExpr, BoolExpr> trueBranch = compute(i.getTrueStatements(), p1, initialResult());
                    p.debug("False Branch");
                    TransferResult<BoolExpr, BoolExpr> falseBranch = compute(i.getFalseStatements(), p2, initialResult());
                    p.debug("JOIN");
                    PList<Pair<String, Pair<Expr, Expr>>> pairs = trueBranch.mergeChangedVariables(falseBranch);
                    // Extract and deal with the return value first so that other
                    // variables have this reflected in their value
                    int idx = pairs.find(pair -> pair.getFirst().equals("RETURN"));
                    if (idx >= 0) {
                        Pair<String, Pair<Expr, Expr>> ret = pairs.get(idx);
                        pairs = pairs.minus(idx);
                        pairs = pairs.plus(pairs.size(), ret);
                    }
                    for (Pair<String, Pair<Expr, Expr>> pair : pairs) {
                        String s = pair.getFirst();
                        p.debug("CHANGED: " + s);
                        Pair<Expr, Expr> x = joinPoint(p, result, guard, pair);
                        result = result.addChangedVariable(s, x.getFirst());
                        if (s.equals("RETURN")) {
                            result = result.setReturnValue((BoolExpr) x.getFirst()).setReturnAssignedValue((BoolExpr) x.getSecond());
                        }
                        if (s.equals("FALLTHROUGH")) {
                            result = result.setFallthroughValue((BoolExpr) x.getFirst()).setReturnAssignedValue((BoolExpr) x.getSecond());
                        }
                    }
                    break;
            }
        } else if (stmt instanceof SetDefaultPolicy) {
            p.debug("SetDefaultPolicy");
            p = p.setDefaultPolicy((SetDefaultPolicy) stmt);
        } else if (stmt instanceof SetMetric) {
            p.debug("SetMetric");
            // TODO: what is the semantics for BGP? Is this MED?
            if (!_current.getProto().isBgp()) {
                SetMetric sm = (SetMetric) stmt;
                LongExpr ie = sm.getMetric();
                ArithExpr newValue = applyLongExprModification(p.getData().getMetric(), ie);
                newValue = _enc.mkIf(result.getReturnAssignedValue(), p.getData().getMetric(), newValue);
                ArithExpr x = createArithVariableWith(p, "METRIC", newValue);
                p.getData().setMetric(x);
                result = result.addChangedVariable("METRIC", x);
            }
        } else if (stmt instanceof SetOspfMetricType) {
            p.debug("SetOspfMetricType");
            SetOspfMetricType somt = (SetOspfMetricType) stmt;
            OspfMetricType mt = somt.getMetricType();
            SymbolicOspfType t;
            if (mt == OspfMetricType.E1) {
                t = new SymbolicOspfType(_enc, OspfType.E1);
            } else {
                t = new SymbolicOspfType(_enc, OspfType.E2);
            }
            BitVecExpr newValue = t.getBitVec();
            newValue = _enc.mkIf(result.getReturnAssignedValue(), p.getData().getOspfType().getBitVec(), newValue);
            BitVecExpr x = createBitVecVariableWith(p, "OSPF-TYPE", 2, newValue);
            p.getData().getOspfType().setBitVec(x);
            result = result.addChangedVariable("OSPF-TYPE", x);
        } else if (stmt instanceof SetLocalPreference) {
            p.debug("SetLocalPreference");
            SetLocalPreference slp = (SetLocalPreference) stmt;
            IntExpr ie = slp.getLocalPreference();
            ArithExpr newValue = applyIntExprModification(p.getData().getLocalPref(), ie);
            newValue = _enc.mkIf(result.getReturnAssignedValue(), p.getData().getLocalPref(), newValue);
            ArithExpr x = createArithVariableWith(p, "LOCAL-PREF", newValue);
            p.getData().setLocalPref(x);
            result = result.addChangedVariable("LOCAL-PREF", x);
        } else if (stmt instanceof AddCommunity) {
            p.debug("AddCommunity");
            AddCommunity ac = (AddCommunity) stmt;
            Set<CommunityVar> comms = _enc.getGraph().findAllCommunities(_conf, ac.getExpr());
            for (CommunityVar cvar : comms) {
                BoolExpr newValue = _enc.mkIf(result.getReturnAssignedValue(), p.getData().getCommunities().get(cvar), _enc.mkTrue());
                BoolExpr x = createBoolVariableWith(p, cvar.getValue(), newValue);
                p.getData().getCommunities().put(cvar, x);
                result = result.addChangedVariable(cvar.getValue(), x);
            }
        } else if (stmt instanceof SetCommunity) {
            p.debug("SetCommunity");
            SetCommunity sc = (SetCommunity) stmt;
            Set<CommunityVar> comms = _enc.getGraph().findAllCommunities(_conf, sc.getExpr());
            for (CommunityVar cvar : comms) {
                BoolExpr newValue = _enc.mkIf(result.getReturnAssignedValue(), p.getData().getCommunities().get(cvar), _enc.mkTrue());
                BoolExpr x = createBoolVariableWith(p, cvar.getValue(), newValue);
                p.getData().getCommunities().put(cvar, x);
                result = result.addChangedVariable(cvar.getValue(), x);
            }
        } else if (stmt instanceof DeleteCommunity) {
            p.debug("DeleteCommunity");
            DeleteCommunity ac = (DeleteCommunity) stmt;
            Set<CommunityVar> comms = _enc.getGraph().findAllCommunities(_conf, ac.getExpr());
            Set<CommunityVar> toDelete = new HashSet<>();
            // Find comms to delete
            for (CommunityVar cvar : comms) {
                if (cvar.getType() == Type.REGEX) {
                    toDelete.addAll(_enc.getCommunityDependencies().get(cvar));
                } else {
                    toDelete.add(cvar);
                }
            }
            // Delete each community
            for (CommunityVar cvar : toDelete) {
                BoolExpr newValue = _enc.mkIf(result.getReturnAssignedValue(), p.getData().getCommunities().get(cvar), _enc.mkFalse());
                BoolExpr x = createBoolVariableWith(p, cvar.getValue(), newValue);
                p.getData().getCommunities().put(cvar, x);
                result = result.addChangedVariable(cvar.getValue(), x);
            }
        } else if (stmt instanceof RetainCommunity) {
            p.debug("RetainCommunity");
        // no op
        } else if (stmt instanceof PrependAsPath) {
            p.debug("PrependAsPath");
            PrependAsPath pap = (PrependAsPath) stmt;
            Integer prependCost = prependLength(pap.getExpr());
            ArithExpr newValue = _enc.mkSum(p.getData().getMetric(), _enc.mkInt(prependCost));
            newValue = _enc.mkIf(result.getReturnAssignedValue(), p.getData().getMetric(), newValue);
            ArithExpr x = createArithVariableWith(p, "METRIC", newValue);
            p.getData().setMetric(x);
            result = result.addChangedVariable("METRIC", x);
        } else if (stmt instanceof SetOrigin) {
            p.debug("SetOrigin");
            System.out.println("Warning: use of unimplemented feature SetOrigin");
        } else if (stmt instanceof SetNextHop) {
            p.debug("SetNextHop");
            System.out.println("Warning: use of unimplemented feature SetNextHop");
        } else {
            String s = (_isExport ? "export" : "import");
            String msg = String.format("Unimplemented feature %s for %s transfer function on interface %s", stmt.toString(), s, _graphEdge.toString());
            throw new BatfishException(msg);
        }
    }
    // If this is the outermost call, then we relate the variables
    if (p.getInitialCall()) {
        p.debug("InitialCall finalizing");
        // Apply the default action
        if (!doesReturn) {
            p.debug("Applying default action: " + p.getDefaultAccept());
            if (p.getDefaultAccept()) {
                result = returnValue(p, result, true);
            } else {
                result = returnValue(p, result, false);
            }
        }
        BoolExpr related = relateVariables(p, result);
        BoolExpr retValue = _enc.mkIf(result.getReturnValue(), related, _enc.mkNot(_current.getPermitted()));
        result = result.setReturnValue(retValue);
    }
    return result;
}

Example 14 with BitVecExpr

use of com.microsoft.z3.BitVecExpr in project batfish by batfish.

the class TransferSSA method createBitVecVariableWith.

private BitVecExpr createBitVecVariableWith(TransferParam<SymbolicRoute> p, String name, int size, BitVecExpr e) {
    e = (BitVecExpr) e.simplify();
    if (canInline(e)) {
        p.debug(name + "=" + e);
        return e;
    }
    String s = "SSA_" + name + generateId();
    BitVecExpr x = _enc.getCtx().mkBVConst(s, size);
    // _enc.getAllVariables().add(x);
    BoolExpr eq = _enc.mkEq(x, e);
    _enc.add(eq);
    p.debug(eq.toString());
    return x;
}

Example 15 with BitVecExpr

use of com.microsoft.z3.BitVecExpr in project batfish by batfish.

the class AbstractNodJob method getOriginateVrfConstraints.

/**
 * Try to find a model for each OriginateVrf. If an OriginateVrf does not have an entry in the
 * Map, then the query is unsat when originating from there.
 */
protected Map<OriginateVrf, Map<String, Long>> getOriginateVrfConstraints(Context ctx, SmtInput smtInput) {
    Solver solver = ctx.mkSolver();
    solver.add(smtInput._expr);
    int originateVrfBvSize = _originateVrfInstrumentation.getFieldBits();
    BitVecExpr originateVrfFieldConst = ctx.mkBVConst(OriginateVrfInstrumentation.ORIGINATE_VRF_FIELD_NAME, originateVrfBvSize);
    ImmutableMap.Builder<OriginateVrf, Map<String, Long>> models = ImmutableMap.builder();
    // keep refining until no new models
    while (true) {
        try {
            Map<String, Long> constraints = getSolution(solver, smtInput._variablesAsConsts);
            int originateVrfId = Math.toIntExact(constraints.get(OriginateVrfInstrumentation.ORIGINATE_VRF_FIELD_NAME));
            OriginateVrf originateVrf = _originateVrfInstrumentation.getOriginateVrfs().get(originateVrfId);
            models.put(originateVrf, constraints);
            // refine: different OriginateVrf
            solver.add(ctx.mkNot(ctx.mkEq(originateVrfFieldConst, ctx.mkBV(originateVrfId, originateVrfBvSize))));
        } catch (QueryUnsatException e) {
            break;
        }
    }
    return models.build();
}