Examples with AddCommunity org.batfish.datamodel.routing_policy.statement.AddCommunity used on opensource projects

Example 1 with AddCommunity

use of org.batfish.datamodel.routing_policy.statement.AddCommunity in project batfish by batfish.

the class Graph method findAllCommunities.

public Set<CommunityVar> findAllCommunities(String router) {
    Set<CommunityVar> comms = new HashSet<>();
    Configuration conf = getConfigurations().get(router);
    for (RoutingPolicy pol : conf.getRoutingPolicies().values()) {
        AstVisitor v = new AstVisitor();
        v.visit(conf, pol.getStatements(), stmt -> {
            if (stmt instanceof SetCommunity) {
                SetCommunity sc = (SetCommunity) stmt;
                comms.addAll(findAllCommunities(conf, sc.getExpr()));
            }
            if (stmt instanceof AddCommunity) {
                AddCommunity ac = (AddCommunity) stmt;
                comms.addAll(findAllCommunities(conf, ac.getExpr()));
            }
            if (stmt instanceof DeleteCommunity) {
                DeleteCommunity dc = (DeleteCommunity) stmt;
                comms.addAll(findAllCommunities(conf, dc.getExpr()));
            }
            if (stmt instanceof RetainCommunity) {
                RetainCommunity rc = (RetainCommunity) stmt;
                comms.addAll(findAllCommunities(conf, rc.getExpr()));
            }
        }, expr -> {
            if (expr instanceof MatchCommunitySet) {
                MatchCommunitySet m = (MatchCommunitySet) expr;
                CommunitySetExpr ce = m.getExpr();
                comms.addAll(findAllCommunities(conf, ce));
            }
        });
    }
    return comms;
}

Example 2 with AddCommunity

use of org.batfish.datamodel.routing_policy.statement.AddCommunity in project batfish by batfish.

the class PsThenCommunityAdd method applyTo.

@Override
public void applyTo(List<Statement> statements, JuniperConfiguration juniperVendorConfiguration, Configuration c, Warnings warnings) {
    CommunityList namedList = _configuration.getCommunityLists().get(_name);
    if (namedList == null) {
        warnings.redFlag("Reference to undefined community: \"" + _name + "\"");
        return;
    } else {
        SortedSet<Long> communities = new TreeSet<>();
        for (CommunityListLine clLine : namedList.getLines()) {
            // assuming that regex here is actually a literal community
            String communityStr = clLine.getRegex();
            long communityLong = CommonUtil.communityStringToLong(communityStr);
            communities.add(communityLong);
        }
        statements.add(new AddCommunity(new InlineCommunitySet(communities)));
    }
}

Example 3 with AddCommunity

use of org.batfish.datamodel.routing_policy.statement.AddCommunity in project batfish by batfish.

the class TransferBDD method compute.

/*
   * Convert a list of statements into a Z3 boolean expression for the transfer function.
   */
private TransferResult<TransferReturn, BDD> compute(List<Statement> statements, TransferParam<BDDRoute> p) {
    boolean doesReturn = false;
    TransferResult<TransferReturn, BDD> result = new TransferResult<>();
    result = result.setReturnValue(new TransferReturn(p.getData(), factory.zero())).setFallthroughValue(factory.zero()).setReturnAssignedValue(factory.zero());
    for (Statement stmt : statements) {
        if (stmt instanceof StaticStatement) {
            StaticStatement ss = (StaticStatement) stmt;
            switch(ss.getType()) {
                case ExitAccept:
                    doesReturn = true;
                    p.debug("ExitAccept");
                    result = returnValue(result, true);
                    break;
                case ReturnTrue:
                    doesReturn = true;
                    p.debug("ReturnTrue");
                    result = returnValue(result, true);
                    break;
                case ExitReject:
                    doesReturn = true;
                    p.debug("ExitReject");
                    result = returnValue(result, false);
                    break;
                case ReturnFalse:
                    doesReturn = true;
                    p.debug("ReturnFalse");
                    result = returnValue(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(result, true);
                    } else {
                        result = returnValue(result, false);
                    }
                    break;
                case FallThrough:
                    p.debug("Fallthrough");
                    result = fallthrough(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<TransferReturn, BDD> r = compute(i.getGuard(), p.indent());
            BDD guard = r.getReturnValue().getSecond();
            p.debug("guard: ");
            BDDRoute current = result.getReturnValue().getFirst();
            TransferParam<BDDRoute> pTrue = p.indent().setData(current.deepCopy());
            TransferParam<BDDRoute> pFalse = p.indent().setData(current.deepCopy());
            p.debug("True Branch");
            TransferResult<TransferReturn, BDD> trueBranch = compute(i.getTrueStatements(), pTrue);
            p.debug("True Branch: " + trueBranch.getReturnValue().getFirst().hashCode());
            p.debug("False Branch");
            TransferResult<TransferReturn, BDD> falseBranch = compute(i.getFalseStatements(), pFalse);
            p.debug("False Branch: " + trueBranch.getReturnValue().getFirst().hashCode());
            BDDRoute r1 = trueBranch.getReturnValue().getFirst();
            BDDRoute r2 = falseBranch.getReturnValue().getFirst();
            BDDRoute recordVal = ite(guard, r1, r2);
            // update return values
            BDD returnVal = ite(guard, trueBranch.getReturnValue().getSecond(), falseBranch.getReturnValue().getSecond());
            // p.debug("New Return Value (neg): " + returnVal.not());
            BDD returnAss = ite(guard, trueBranch.getReturnAssignedValue(), falseBranch.getReturnAssignedValue());
            // p.debug("New Return Assigned: " + returnAss);
            BDD fallThrough = ite(guard, trueBranch.getFallthroughValue(), falseBranch.getFallthroughValue());
            // p.debug("New fallthrough: " + fallThrough);
            result = result.setReturnValue(new TransferReturn(recordVal, returnVal)).setReturnAssignedValue(returnAss).setFallthroughValue(fallThrough);
            p.debug("If return: " + result.getReturnValue().getFirst().hashCode());
        } else if (stmt instanceof SetDefaultPolicy) {
            p.debug("SetDefaultPolicy");
            p = p.setDefaultPolicy((SetDefaultPolicy) stmt);
        } else if (stmt instanceof SetMetric) {
            p.debug("SetMetric");
            SetMetric sm = (SetMetric) stmt;
            LongExpr ie = sm.getMetric();
            BDD isBGP = p.getData().getProtocolHistory().value(Protocol.BGP);
            BDD updateMed = isBGP.and(result.getReturnAssignedValue());
            BDD updateMet = isBGP.not().and(result.getReturnAssignedValue());
            BDDInteger newValue = applyLongExprModification(p.indent(), p.getData().getMetric(), ie);
            BDDInteger med = ite(updateMed, p.getData().getMed(), newValue);
            BDDInteger met = ite(updateMet, p.getData().getMetric(), newValue);
            p.getData().setMetric(met);
            p.getData().setMetric(med);
        } else if (stmt instanceof SetOspfMetricType) {
            p.debug("SetOspfMetricType");
            SetOspfMetricType somt = (SetOspfMetricType) stmt;
            OspfMetricType mt = somt.getMetricType();
            BDDDomain<OspfType> current = result.getReturnValue().getFirst().getOspfMetric();
            BDDDomain<OspfType> newValue = new BDDDomain<>(current);
            if (mt == OspfMetricType.E1) {
                p.indent().debug("Value: E1");
                newValue.setValue(OspfType.E1);
            } else {
                p.indent().debug("Value: E2");
                newValue.setValue(OspfType.E1);
            }
            newValue = ite(result.getReturnAssignedValue(), p.getData().getOspfMetric(), newValue);
            p.getData().setOspfMetric(newValue);
        } else if (stmt instanceof SetLocalPreference) {
            p.debug("SetLocalPreference");
            SetLocalPreference slp = (SetLocalPreference) stmt;
            IntExpr ie = slp.getLocalPreference();
            BDDInteger newValue = applyIntExprModification(p.indent(), p.getData().getLocalPref(), ie);
            newValue = ite(result.getReturnAssignedValue(), p.getData().getLocalPref(), newValue);
            p.getData().setLocalPref(newValue);
        } else if (stmt instanceof AddCommunity) {
            p.debug("AddCommunity");
            AddCommunity ac = (AddCommunity) stmt;
            Set<CommunityVar> comms = _graph.findAllCommunities(_conf, ac.getExpr());
            for (CommunityVar cvar : comms) {
                if (!_policyQuotient.getCommsAssignedButNotMatched().contains(cvar)) {
                    p.indent().debug("Value: " + cvar);
                    BDD comm = p.getData().getCommunities().get(cvar);
                    BDD newValue = ite(result.getReturnAssignedValue(), comm, factory.one());
                    p.indent().debug("New Value: " + newValue);
                    p.getData().getCommunities().put(cvar, newValue);
                }
            }
        } else if (stmt instanceof SetCommunity) {
            p.debug("SetCommunity");
            SetCommunity sc = (SetCommunity) stmt;
            Set<CommunityVar> comms = _graph.findAllCommunities(_conf, sc.getExpr());
            for (CommunityVar cvar : comms) {
                if (!_policyQuotient.getCommsAssignedButNotMatched().contains(cvar)) {
                    p.indent().debug("Value: " + cvar);
                    BDD comm = p.getData().getCommunities().get(cvar);
                    BDD newValue = ite(result.getReturnAssignedValue(), comm, factory.one());
                    p.indent().debug("New Value: " + newValue);
                    p.getData().getCommunities().put(cvar, newValue);
                }
            }
        } else if (stmt instanceof DeleteCommunity) {
            p.debug("DeleteCommunity");
            DeleteCommunity ac = (DeleteCommunity) stmt;
            Set<CommunityVar> comms = _graph.findAllCommunities(_conf, ac.getExpr());
            Set<CommunityVar> toDelete = new HashSet<>();
            // Find comms to delete
            for (CommunityVar cvar : comms) {
                if (cvar.getType() == Type.REGEX) {
                    toDelete.addAll(_commDeps.get(cvar));
                } else {
                    toDelete.add(cvar);
                }
            }
            // Delete the comms
            for (CommunityVar cvar : toDelete) {
                if (!_policyQuotient.getCommsAssignedButNotMatched().contains(cvar)) {
                    p.indent().debug("Value: " + cvar.getValue() + ", " + cvar.getType());
                    BDD comm = p.getData().getCommunities().get(cvar);
                    BDD newValue = ite(result.getReturnAssignedValue(), comm, factory.zero());
                    p.indent().debug("New Value: " + newValue);
                    p.getData().getCommunities().put(cvar, newValue);
                }
            }
        } 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());
            p.indent().debug("Cost: " + prependCost);
            BDDInteger met = p.getData().getMetric();
            BDDInteger newValue = met.add(BDDInteger.makeFromValue(met.getFactory(), 32, prependCost));
            newValue = ite(result.getReturnAssignedValue(), p.getData().getMetric(), newValue);
            p.getData().setMetric(newValue);
        } else if (stmt instanceof SetOrigin) {
            p.debug("SetOrigin");
        // System.out.println("Warning: use of unimplemented feature SetOrigin");
        // TODO: implement me
        } else if (stmt instanceof SetNextHop) {
            p.debug("SetNextHop");
        // System.out.println("Warning: use of unimplemented feature SetNextHop");
        // TODO: implement me
        } else {
            throw new BatfishException("TODO: statement transfer function: " + stmt);
        }
    }
    // 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(result, true);
            } else {
                result = returnValue(result, false);
            }
        }
        // Set all the values to 0 if the return is not true;
        TransferReturn ret = result.getReturnValue();
        BDDRoute retVal = ite(ret.getSecond(), ret.getFirst(), zeroedRecord());
        result = result.setReturnValue(new TransferReturn(retVal, ret.getSecond()));
    }
    return result;
}

Example 4 with AddCommunity

use of org.batfish.datamodel.routing_policy.statement.AddCommunity in project batfish by batfish.

the class RouteMapSetAdditiveCommunityListLine method applyTo.

@Override
public void applyTo(List<Statement> statements, CiscoConfiguration cc, Configuration c, Warnings w) {
    SortedSet<Long> communities = new TreeSet<>();
    for (String communityListName : _communityLists) {
        CommunityList communityList = c.getCommunityLists().get(communityListName);
        if (communityList != null) {
            StandardCommunityList scl = cc.getStandardCommunityLists().get(communityListName);
            if (scl != null) {
                for (StandardCommunityListLine line : scl.getLines()) {
                    if (line.getAction() == LineAction.ACCEPT) {
                        communities.addAll(line.getCommunities());
                    } else {
                        w.redFlag("Expected only permit lines in standard community-list referred to by route-map " + "set community community-list line: \"" + communityListName + "\"");
                    }
                }
            } else {
                w.redFlag("Expected standard community list in route-map set community community-list line " + "but got expanded instead: \"" + communityListName + "\"");
            }
        } else {
            cc.undefined(CiscoStructureType.COMMUNITY_LIST, communityListName, CiscoStructureUsage.ROUTE_MAP_ADD_COMMUNITY, _statementLine);
        }
    }
    statements.add(new AddCommunity(new InlineCommunitySet(communities)));
}

Example 5 with AddCommunity

use of org.batfish.datamodel.routing_policy.statement.AddCommunity 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;
}