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BgpAdvertisement: cleanup, comment, factor out main code (#6607)
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Understandability, readability, and reusability.
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@dhalperi
dhalperi committed Feb 2, 2021
1 parent cbe1a1f commit 738882b
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31 changes: 31 additions & 0 deletions projects/batfish-common-protocol/src/main/java/org/batfish/datamodel/BgpAdvertisement.java
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,37 @@ public enum BgpAdvertisementType {
IBGP_RECEIVED,
IBGP_SENT;

/** Returns true if this advertisement is from an ebgp peer. */
public boolean isEbgp() {
switch (this) {
case EBGP_ORIGINATED:
case EBGP_RECEIVED:
case EBGP_SENT:
return true;
default:
return false;
}
}

/**
* Returns true if this advertisement is from a device's local view of the route, aka, it has
* already been processed/filtered by import policy. These routes are installed directly in the
* RIB.
*/
public boolean isReceived() {
switch (this) {
case EBGP_RECEIVED:
case IBGP_RECEIVED:
return true;
case EBGP_SENT:
case IBGP_SENT:
return false;
default:
// include originated.
throw new BatfishException("Missing or invalid bgp advertisement type");
}
}

private static final Map<String, BgpAdvertisementType> _map = buildMap();

private static Map<String, BgpAdvertisementType> buildMap() {
Expand Down
270 changes: 115 additions & 155 deletions projects/batfish/src/main/java/org/batfish/dataplane/ibdp/BgpRoutingProcess.java
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,6 @@
import javax.annotation.ParametersAreNonnullByDefault;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.batfish.common.BatfishException;
import org.batfish.datamodel.AbstractRoute;
import org.batfish.datamodel.AbstractRouteDecorator;
import org.batfish.datamodel.AnnotatedRoute;
Expand Down Expand Up @@ -1417,6 +1416,112 @@ Bgpv4Route exportNonBgpRouteToBgp(
return transformedOutgoingRoute;
}

private void processExternalBgpAdvertisement(
BgpAdvertisement advert, Map<Bgpv4Rib, RibDelta.Builder<Bgpv4Route>> ribDeltas) {
Ip srcIp = advert.getSrcIp();
// TODO: support passive and unnumbered bgp connections
Prefix srcPrefix = srcIp.toPrefix();
BgpPeerConfig neighbor = _process.getActiveNeighbors().get(srcPrefix);
assert neighbor != null; // invariant of being processed

// Build a route based on the type of this advertisement
BgpAdvertisementType type = advert.getType();
boolean ebgp = type.isEbgp();

Bgpv4Rib targetRib = ebgp ? _ebgpv4Rib : _ibgpv4Rib;
RoutingProtocol targetProtocol = ebgp ? RoutingProtocol.BGP : RoutingProtocol.IBGP;

// Route advertisement does not contain its admin distance.
int admin = _process.getAdminCost(targetProtocol);

if (type.isReceived()) {
// Since the route is received, it is from a post-import-chain view of the route.
// Copy its attributes directly where possible then directly import it into the RIB.
Bgpv4Route route =
Bgpv4Route.testBuilder()
.setAdmin(admin)
.setAsPath(advert.getAsPath())
.setClusterList(advert.getClusterList())
.setCommunities(advert.getCommunities())
.setLocalPreference(advert.getLocalPreference())
.setMetric(advert.getMed())
.setNetwork(advert.getNetwork())
.setNextHopIp(advert.getNextHopIp())
.setOriginatorIp(advert.getOriginatorIp())
.setOriginType(advert.getOriginType())
.setProtocol(targetProtocol)
.setReceivedFromIp(advert.getSrcIp())
// TODO: support external route reflector clients
.setReceivedFromRouteReflectorClient(false)
.setSrcProtocol(advert.getSrcProtocol())
// TODO: possibly support setting tag
.setWeight(advert.getWeight())
.build();
ribDeltas.get(targetRib).from(targetRib.mergeRouteGetDelta(route));
} else {
// Since the route was logged after sending, it is from a pre-import-chain view of the route.
// Override some attributes with local ones, then send it through the import policy.
long localPreference;
if (ebgp) {
localPreference = Bgpv4Route.DEFAULT_LOCAL_PREFERENCE;
} else {
localPreference = advert.getLocalPreference();
}
Bgpv4Route transformedOutgoingRoute =
Bgpv4Route.testBuilder()
.setAsPath(advert.getAsPath())
.setClusterList(advert.getClusterList())
.setCommunities(ImmutableSortedSet.copyOf(advert.getCommunities()))
.setLocalPreference(localPreference)
.setMetric(advert.getMed())
.setNetwork(advert.getNetwork())
.setNextHopIp(advert.getNextHopIp())
.setOriginatorIp(advert.getOriginatorIp())
.setOriginType(advert.getOriginType())
.setProtocol(targetProtocol)
.setReceivedFromIp(advert.getSrcIp())
// TODO .setReceivedFromRouteReflectorClient(...)
.setSrcProtocol(advert.getSrcProtocol())
.build();
Bgpv4Route.Builder transformedIncomingRouteBuilder =
Bgpv4Route.testBuilder()
.setAdmin(admin)
.setAsPath(transformedOutgoingRoute.getAsPath())
.setClusterList(transformedOutgoingRoute.getClusterList())
.setCommunities(transformedOutgoingRoute.getCommunities().getCommunities())
.setLocalPreference(transformedOutgoingRoute.getLocalPreference())
.setMetric(transformedOutgoingRoute.getMetric())
.setNetwork(transformedOutgoingRoute.getNetwork())
.setNextHopIp(transformedOutgoingRoute.getNextHopIp())
.setOriginType(transformedOutgoingRoute.getOriginType())
.setOriginatorIp(transformedOutgoingRoute.getOriginatorIp())
.setReceivedFromIp(transformedOutgoingRoute.getReceivedFromIp())
.setReceivedFromRouteReflectorClient(
transformedOutgoingRoute.getReceivedFromRouteReflectorClient())
.setProtocol(targetProtocol)
.setSrcProtocol(targetProtocol);
String importPolicyName = neighbor.getIpv4UnicastAddressFamily().getImportPolicy();
// TODO: ensure there is always an import policy

/*
* CREATE INCOMING ROUTE
*/
boolean acceptIncoming = true;
if (importPolicyName != null) {
RoutingPolicy importPolicy = _policies.get(importPolicyName).orElse(null);
if (importPolicy != null) {
// TODO Figure out whether transformedOutgoingRoute ought to have an annotation
acceptIncoming =
importPolicy.process(transformedOutgoingRoute, transformedIncomingRouteBuilder, IN);
}
}
if (acceptIncoming) {
Bgpv4Route transformedIncomingRoute = transformedIncomingRouteBuilder.build();
ribDeltas.get(targetRib).from(targetRib.mergeRouteGetDelta(transformedIncomingRoute));
}
}
}

/**
* Initializes BGP RIBs prior to any dataplane iterations based on the external BGP advertisements
* coming into the network.
Expand All @@ -1435,7 +1540,6 @@ void processExternalBgpAdvertisements(
ribDeltas.put(_ebgpv4Rib, RibDelta.builder());
ribDeltas.put(_ibgpv4Rib, RibDelta.builder());

Bgpv4Route.Builder outgoingRouteBuilder = Bgpv4Route.testBuilder();
// Process each BGP advertisement
for (BgpAdvertisement advert : externalAdverts) {

Expand All @@ -1460,161 +1564,17 @@ void processExternalBgpAdvertisements(
continue;
}

// Build a route based on the type of this advertisement
BgpAdvertisementType type = advert.getType();
boolean ebgp;
boolean received;
switch (type) {
case EBGP_RECEIVED:
ebgp = true;
received = true;
break;

case EBGP_SENT:
ebgp = true;
received = false;
break;

case IBGP_RECEIVED:
ebgp = false;
received = true;
break;

case IBGP_SENT:
ebgp = false;
received = false;
break;

case EBGP_ORIGINATED:
case IBGP_ORIGINATED:
default:
throw new BatfishException("Missing or invalid bgp advertisement type");
if (advert.getType().isEbgp()
&& advert.getAsPath().containsAs(neighbor.getLocalAs())
&& !neighbor
.getIpv4UnicastAddressFamily()
.getAddressFamilyCapabilities()
.getAllowLocalAsIn()) {
// skip routes containing this peer's AS unless the session is configured to allow loops.
continue;
}

Bgpv4Rib targetRib = ebgp ? _ebgpv4Rib : _ibgpv4Rib;
RoutingProtocol targetProtocol = ebgp ? RoutingProtocol.BGP : RoutingProtocol.IBGP;
int admin = _process.getAdminCost(targetProtocol);

if (received) {
Bgpv4Route.Builder builder = Bgpv4Route.testBuilder();
builder.setAdmin(admin);
builder.setAsPath(advert.getAsPath());
builder.setClusterList(advert.getClusterList());
builder.setCommunities(advert.getCommunities());
builder.setLocalPreference(advert.getLocalPreference());
builder.setMetric(advert.getMed());
builder.setNetwork(advert.getNetwork());
builder.setNextHopIp(advert.getNextHopIp());
builder.setOriginatorIp(advert.getOriginatorIp());
builder.setOriginType(advert.getOriginType());
builder.setProtocol(targetProtocol);
// TODO: support external route reflector clients
builder.setReceivedFromIp(advert.getSrcIp());
builder.setReceivedFromRouteReflectorClient(false);
builder.setSrcProtocol(advert.getSrcProtocol());
// TODO: possibly support setting tag
builder.setWeight(advert.getWeight());
Bgpv4Route route = builder.build();
ribDeltas.get(targetRib).from(targetRib.mergeRouteGetDelta(route));
} else {
long localPreference;
if (ebgp) {
localPreference = Bgpv4Route.DEFAULT_LOCAL_PREFERENCE;
} else {
localPreference = advert.getLocalPreference();
}
outgoingRouteBuilder.setAsPath(advert.getAsPath());
outgoingRouteBuilder.setCommunities(ImmutableSortedSet.copyOf(advert.getCommunities()));
outgoingRouteBuilder.setLocalPreference(localPreference);
outgoingRouteBuilder.setMetric(advert.getMed());
outgoingRouteBuilder.setNetwork(advert.getNetwork());
outgoingRouteBuilder.setNextHopIp(advert.getNextHopIp());
outgoingRouteBuilder.setOriginatorIp(advert.getOriginatorIp());
outgoingRouteBuilder.setOriginType(advert.getOriginType());
outgoingRouteBuilder.setProtocol(targetProtocol);
outgoingRouteBuilder.setReceivedFromIp(advert.getSrcIp());
// TODO:
// outgoingRouteBuilder.setReceivedFromRouteReflectorClient(...);
outgoingRouteBuilder.setSrcProtocol(advert.getSrcProtocol());
Bgpv4Route transformedOutgoingRoute = outgoingRouteBuilder.build();
Bgpv4Route.Builder transformedIncomingRouteBuilder = Bgpv4Route.testBuilder();

// Incoming originatorIp
transformedIncomingRouteBuilder.setOriginatorIp(transformedOutgoingRoute.getOriginatorIp());

// Incoming receivedFromIp
transformedIncomingRouteBuilder.setReceivedFromIp(
transformedOutgoingRoute.getReceivedFromIp());

// Incoming clusterList
transformedIncomingRouteBuilder.addClusterList(transformedOutgoingRoute.getClusterList());

// Incoming receivedFromRouteReflectorClient
transformedIncomingRouteBuilder.setReceivedFromRouteReflectorClient(
transformedOutgoingRoute.getReceivedFromRouteReflectorClient());

// Incoming asPath
transformedIncomingRouteBuilder.setAsPath(transformedOutgoingRoute.getAsPath());

// Incoming communities
transformedIncomingRouteBuilder.addCommunities(
transformedOutgoingRoute.getCommunities().getCommunities());

// Incoming protocol
transformedIncomingRouteBuilder.setProtocol(targetProtocol);

// Incoming network
transformedIncomingRouteBuilder.setNetwork(transformedOutgoingRoute.getNetwork());

// Incoming nextHopIp
transformedIncomingRouteBuilder.setNextHopIp(transformedOutgoingRoute.getNextHopIp());

// Incoming originType
transformedIncomingRouteBuilder.setOriginType(transformedOutgoingRoute.getOriginType());

// Incoming localPreference
transformedIncomingRouteBuilder.setLocalPreference(
transformedOutgoingRoute.getLocalPreference());

// Incoming admin
transformedIncomingRouteBuilder.setAdmin(admin);

// Incoming metric
transformedIncomingRouteBuilder.setMetric(transformedOutgoingRoute.getMetric());

// Incoming srcProtocol
transformedIncomingRouteBuilder.setSrcProtocol(targetProtocol);
String importPolicyName = neighbor.getIpv4UnicastAddressFamily().getImportPolicy();
// TODO: ensure there is always an import policy

if (ebgp
&& transformedOutgoingRoute.getAsPath().containsAs(neighbor.getLocalAs())
&& !neighbor
.getIpv4UnicastAddressFamily()
.getAddressFamilyCapabilities()
.getAllowLocalAsIn()) {
// skip routes containing peer's AS unless
// disable-peer-as-check (getAllowRemoteAsOut) is set
continue;
}

/*
* CREATE INCOMING ROUTE
*/
boolean acceptIncoming = true;
if (importPolicyName != null) {
RoutingPolicy importPolicy = _policies.get(importPolicyName).orElse(null);
if (importPolicy != null) {
// TODO Figure out whether transformedOutgoingRoute ought to have an annotation
acceptIncoming =
importPolicy.process(transformedOutgoingRoute, transformedIncomingRouteBuilder, IN);
}
}
if (acceptIncoming) {
Bgpv4Route transformedIncomingRoute = transformedIncomingRouteBuilder.build();
ribDeltas.get(targetRib).from(targetRib.mergeRouteGetDelta(transformedIncomingRoute));
}
}
processExternalBgpAdvertisement(advert, ribDeltas);
}

// Propagate received routes through all the RIBs
Expand Down

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