Examples with SmtOneAnswerElement org.batfish.symbolic.answers.SmtOneAnswerElement used on opensource projects

Example 1 with SmtOneAnswerElement

use of org.batfish.symbolic.answers.SmtOneAnswerElement in project batfish by batfish.

the class PropertyChecker method checkRoutingLoop.

/*
   * Checks for routing loops in the network. For efficiency reasons,
   * we only check for loops with routers that use static routes since
   * these can override the usual loop-prevention mechanisms.
   */
public AnswerElement checkRoutingLoop(HeaderQuestion q) {
    Graph graph = new Graph(_batfish);
    // Collect all relevant destinations
    List<Prefix> prefixes = new ArrayList<>();
    graph.getStaticRoutes().forEach((router, ifaceName, srs) -> {
        for (StaticRoute sr : srs) {
            prefixes.add(sr.getNetwork());
        }
    });
    SortedSet<IpWildcard> pfxs = new TreeSet<>();
    for (Prefix prefix : prefixes) {
        pfxs.add(new IpWildcard(prefix));
    }
    q.getHeaderSpace().setDstIps(pfxs);
    // Collect all routers that use static routes as a
    // potential node along a loop
    List<String> routers = new ArrayList<>();
    for (Entry<String, Configuration> entry : graph.getConfigurations().entrySet()) {
        String router = entry.getKey();
        Configuration conf = entry.getValue();
        if (conf.getDefaultVrf().getStaticRoutes().size() > 0) {
            routers.add(router);
        }
    }
    Encoder enc = new Encoder(_settings, graph, q);
    enc.computeEncoding();
    Context ctx = enc.getCtx();
    EncoderSlice slice = enc.getMainSlice();
    PropertyAdder pa = new PropertyAdder(slice);
    BoolExpr someLoop = ctx.mkBool(false);
    for (String router : routers) {
        BoolExpr hasLoop = pa.instrumentLoop(router);
        someLoop = ctx.mkOr(someLoop, hasLoop);
    }
    enc.add(someLoop);
    VerificationResult result = enc.verify().getFirst();
    return new SmtOneAnswerElement(result);
}

Example 2 with SmtOneAnswerElement

use of org.batfish.symbolic.answers.SmtOneAnswerElement in project batfish by batfish.

the class PropertyChecker method checkBlackHole.

/*
   * Compute if there can ever be a black hole for routers that are
   * not at the edge of the network. This is almost certainly a bug.
   */
public AnswerElement checkBlackHole(HeaderQuestion q) {
    Graph graph = new Graph(_batfish);
    Encoder enc = new Encoder(_settings, graph, q);
    enc.computeEncoding();
    Context ctx = enc.getCtx();
    EncoderSlice slice = enc.getMainSlice();
    // Collect routers that have no host/environment edge
    List<String> toCheck = new ArrayList<>();
    for (Entry<String, List<GraphEdge>> entry : graph.getEdgeMap().entrySet()) {
        String router = entry.getKey();
        List<GraphEdge> edges = entry.getValue();
        boolean check = true;
        for (GraphEdge edge : edges) {
            if (edge.getEnd() == null) {
                check = false;
                break;
            }
        }
        if (check) {
            toCheck.add(router);
        }
    }
    // Ensure the router never receives traffic and then drops the traffic
    BoolExpr someBlackHole = ctx.mkBool(false);
    for (String router : toCheck) {
        Map<GraphEdge, BoolExpr> edges = slice.getSymbolicDecisions().getDataForwarding().get(router);
        BoolExpr doesNotFwd = ctx.mkBool(true);
        for (Map.Entry<GraphEdge, BoolExpr> entry : edges.entrySet()) {
            BoolExpr dataFwd = entry.getValue();
            doesNotFwd = ctx.mkAnd(doesNotFwd, ctx.mkNot(dataFwd));
        }
        BoolExpr isFwdTo = ctx.mkBool(false);
        Set<String> neighbors = graph.getNeighbors().get(router);
        for (String n : neighbors) {
            for (Map.Entry<GraphEdge, BoolExpr> entry : slice.getSymbolicDecisions().getDataForwarding().get(n).entrySet()) {
                GraphEdge ge = entry.getKey();
                BoolExpr fwd = entry.getValue();
                if (router.equals(ge.getPeer())) {
                    isFwdTo = ctx.mkOr(isFwdTo, fwd);
                }
            }
        }
        someBlackHole = ctx.mkOr(someBlackHole, ctx.mkAnd(isFwdTo, doesNotFwd));
    }
    enc.add(someBlackHole);
    VerificationResult result = enc.verify().getFirst();
    return new SmtOneAnswerElement(result);
}

Example 3 with SmtOneAnswerElement

use of org.batfish.symbolic.answers.SmtOneAnswerElement in project batfish by batfish.

the class PropertyChecker method checkForwarding.

/*
   * Compute the forwarding behavior for the network. This adds no
   * additional constraints on top of the base network encoding.
   * Forwarding will be determined only for a particular network
   * environment, failure scenario, and data plane packet.
   */
public AnswerElement checkForwarding(HeaderQuestion question) {
    long totalTime = System.currentTimeMillis();
    HeaderQuestion q = new HeaderQuestion(question);
    q.setFailures(0);
    Tuple<Stream<Supplier<NetworkSlice>>, Long> ecs = findAllNetworkSlices(q, null, true);
    Stream<Supplier<NetworkSlice>> stream = ecs.getFirst();
    Long timeAbstraction = ecs.getSecond();
    Optional<Supplier<NetworkSlice>> opt = stream.findFirst();
    if (!opt.isPresent()) {
        throw new BatfishException("Unexpected Error: checkForwarding");
    }
    long timeEc = System.currentTimeMillis();
    Supplier<NetworkSlice> sup = opt.get();
    NetworkSlice slice = sup.get();
    timeEc = System.currentTimeMillis() - timeEc;
    Graph g = slice.getGraph();
    q = new HeaderQuestion(q);
    q.setHeaderSpace(slice.getHeaderSpace());
    long timeEncoding = System.currentTimeMillis();
    Encoder encoder = new Encoder(_settings, g, q);
    encoder.computeEncoding();
    addEnvironmentConstraints(encoder, q.getBaseEnvironmentType());
    timeEncoding = System.currentTimeMillis() - timeEncoding;
    VerificationResult result = encoder.verify().getFirst();
    totalTime = System.currentTimeMillis() - totalTime;
    VerificationStats stats = result.getStats();
    if (q.getBenchmark()) {
        stats.setTimeCreateBdds((double) timeAbstraction);
        stats.setTotalTime(totalTime);
        stats.setAvgComputeEcTime(timeEc);
        stats.setMaxComputeEcTime(timeEc);
        stats.setMinComputeEcTime(timeEc);
        stats.setAvgEncodingTime(timeEncoding);
        stats.setMaxEncodingTime(timeEncoding);
        stats.setMinEncodingTime(timeEncoding);
        stats.setTimeCreateBdds((double) timeAbstraction);
    }
    return new SmtOneAnswerElement(result);
}

Example 4 with SmtOneAnswerElement

use of org.batfish.symbolic.answers.SmtOneAnswerElement in project batfish by batfish.

the class PropertyChecker method checkBoundedLength.

/*
   * Compute whether the path length will always be bounded by a constant k
   * for a collection of source routers to any of a number of destination ports.
   */
public AnswerElement checkBoundedLength(HeaderLocationQuestion q, int k) {
    return checkProperty(q, (enc, srcRouters, destPorts) -> {
        ArithExpr bound = enc.mkInt(k);
        PropertyAdder pa = new PropertyAdder(enc.getMainSlice());
        Map<String, ArithExpr> lenVars = pa.instrumentPathLength(destPorts);
        Map<String, BoolExpr> boundVars = new HashMap<>();
        lenVars.forEach((n, ae) -> boundVars.put(n, enc.mkLe(ae, bound)));
        return boundVars;
    }, (vp) -> new SmtOneAnswerElement(vp.getResult()));
}

Example 5 with SmtOneAnswerElement

use of org.batfish.symbolic.answers.SmtOneAnswerElement in project batfish by batfish.

the class PropertyChecker method checkMultipathConsistency.

/*
   * Computes multipath consistency, which ensures traffic that travels
   * multiple paths will be treated equivalently by each path
   * (i.e., dropped or accepted by each).
   */
public AnswerElement checkMultipathConsistency(HeaderLocationQuestion q) {
    if (q.getNegate()) {
        throw new BatfishException("Negation not implemented for smt-multipath-consistency.");
    }
    PathRegexes p = new PathRegexes(q);
    Graph graph = new Graph(_batfish);
    Set<GraphEdge> destPorts = findFinalInterfaces(graph, p);
    inferDestinationHeaderSpace(graph, destPorts, q);
    Encoder enc = new Encoder(_settings, graph, q);
    enc.computeEncoding();
    EncoderSlice slice = enc.getMainSlice();
    PropertyAdder pa = new PropertyAdder(slice);
    Map<String, BoolExpr> reachableVars = pa.instrumentReachability(destPorts);
    BoolExpr acc = enc.mkFalse();
    for (Map.Entry<String, Configuration> entry : graph.getConfigurations().entrySet()) {
        String router = entry.getKey();
        BoolExpr reach = reachableVars.get(router);
        BoolExpr all = enc.mkTrue();
        for (GraphEdge edge : graph.getEdgeMap().get(router)) {
            BoolExpr dataFwd = slice.getForwardsAcross().get(router, edge);
            BoolExpr ctrFwd = slice.getSymbolicDecisions().getControlForwarding().get(router, edge);
            assert (ctrFwd != null);
            BoolExpr peerReach = enc.mkTrue();
            if (edge.getPeer() != null) {
                peerReach = reachableVars.get(edge.getPeer());
            }
            BoolExpr imp = enc.mkImplies(ctrFwd, enc.mkAnd(dataFwd, peerReach));
            all = enc.mkAnd(all, imp);
        }
        acc = enc.mkOr(acc, enc.mkNot(enc.mkImplies(reach, all)));
    }
    enc.add(acc);
    VerificationResult res = enc.verify().getFirst();
    return new SmtOneAnswerElement(res);
}