Add shorter prefix search

Adds a shorter-prefixes search mode that finds any identical-or-less-specific routes
than the input values.

Bug-Url: #1006

Signed-off-by: Ben Agricola bagricola@squiz.co.uk

5 files changed, 31 insertions, 18 deletions

diff --git a/api/gobgp.pb.go b/api/gobgp.pb.go
index 8edf8624..0021c995 100644
--- a/api/gobgp.pb.go
+++ b/api/gobgp.pb.go
@@ -1502,9 +1502,10 @@ func (*Path) ProtoMessage()               {}
 func (*Path) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{92} }
 
 type Destination struct {
-	Prefix         string  `protobuf:"bytes,1,opt,name=prefix" json:"prefix,omitempty"`
-	Paths          []*Path `protobuf:"bytes,2,rep,name=paths" json:"paths,omitempty"`
-	LongerPrefixes bool    `protobuf:"varint,3,opt,name=longer_prefixes,json=longerPrefixes" json:"longer_prefixes,omitempty"`
+	Prefix          string  `protobuf:"bytes,1,opt,name=prefix" json:"prefix,omitempty"`
+	Paths           []*Path `protobuf:"bytes,2,rep,name=paths" json:"paths,omitempty"`
+	LongerPrefixes  bool    `protobuf:"varint,3,opt,name=longer_prefixes,json=longerPrefixes" json:"longer_prefixes,omitempty"`
+	ShorterPrefixes bool    `protobuf:"varint,4,opt,name=shorter_prefixes,json=shorterPrefixes" json:"shorter_prefixes,omitempty"`
 }
 
 func (m *Destination) Reset()                    { *m = Destination{} }
diff --git a/api/gobgp.proto b/api/gobgp.proto
index 8f6f87d6..71a30185 100644
--- a/api/gobgp.proto
+++ b/api/gobgp.proto
@@ -489,6 +489,7 @@ message Destination {
   string prefix = 1;
   repeated Path paths = 2;
   bool longer_prefixes = 3;
+  bool shorter_prefixes = 4;
 }
 
 message Table {
diff --git a/docs/sources/cli-command-syntax.md b/docs/sources/cli-command-syntax.md
index 2ebfec23..c7e359a2 100644
--- a/docs/sources/cli-command-syntax.md
+++ b/docs/sources/cli-command-syntax.md
@@ -40,7 +40,7 @@ gobgp has six subcommands.
 # show all Route information
 % gobgp global rib [-a <address family>]
 # show a specific route information
-% gobgp global rib [<prefix>|<host>] [longer-prefixes] [-a <address family>]
+% gobgp global rib [<prefix>|<host>] [longer-prefixes|shorter-prefixes] [-a <address family>]
 ```
 
 #### - example
@@ -118,7 +118,7 @@ The following options can be specified in the global subcommand:
 # show all routes in [local|adj-in|adj-out] table
 % gobgp neighbor <neighbor address> [local|adj-in|adj-out] [-a <address family>]
 # show a specific route in [local|adj-in|adj-out] table
-% gobgp neighbor <neighbor address> [local|adj-in|adj-out] [<prefix>|<host>] [longer-prefixes] [-a <address family>]
+% gobgp neighbor <neighbor address> [local|adj-in|adj-out] [<prefix>|<host>] [longer-prefixes|shorter-prefixes] [-a <address family>]
 ```
 
 #### - example
diff --git a/gobgp/cmd/neighbor.go b/gobgp/cmd/neighbor.go
index 9c93bbd2..bf687772 100644
--- a/gobgp/cmd/neighbor.go
+++ b/gobgp/cmd/neighbor.go
@@ -483,16 +483,21 @@ func showNeighborRib(r string, name string, args []string) error {
 			return fmt.Errorf("route filtering is only supported for IPv4/IPv6 unicast routes")
 		}
 		longerPrefixes := false
+		shorterPrefixes := false
 		if len(args) > 1 {
-			if args[1] != "longer-prefixes" {
+			if args[1] == "longer-prefixes" {
+				longerPrefixes = true
+			} else if args[1] == "shorter-prefixes" {
+				shorterPrefixes = true
+			} else {
 				return fmt.Errorf("invalid format for route filtering")
 			}
-			longerPrefixes = true
 		}
 		arg.Destinations = []*api.Destination{
 			&api.Destination{
-				Prefix:         args[0],
-				LongerPrefixes: longerPrefixes,
+				Prefix:          args[0],
+				LongerPrefixes:  longerPrefixes,
+				ShorterPrefixes: shorterPrefixes,
 			},
 		}
 	}
diff --git a/server/server.go b/server/server.go
index 6a766261..286ff85b 100644
--- a/server/server.go
+++ b/server/server.go
@@ -1605,7 +1605,21 @@ func (server *BgpServer) handleGrpc(grpcReq *GrpcRequest) {
 			}
 			for _, dst := range arg.Table.Destinations {
 				key := dst.Prefix
-				if _, err := f(id, key); err != nil {
+				if dst.LongerPrefixes {
+					_, prefix, _ := net.ParseCIDR(key)
+					for _, dst := range rib.Tables[af].GetLongerPrefixDestinations(prefix.String()) {
+						if d := dst.ToApiStruct(id); d != nil {
+							dsts = append(dsts, d)
+						}
+					}
+				} else if dst.ShorterPrefixes {
+					_, prefix, _ := net.ParseCIDR(key)
+					ones, bits := prefix.Mask.Size()
+					for i := ones; i > 0; i-- {
+						prefix.Mask = net.CIDRMask(i, bits)
+						f(id, prefix.String())
+					}
+				} else if _, err := f(id, key); err != nil {
 					if host := net.ParseIP(key); host != nil {
 						masklen := 32
 						if af == bgp.RF_IPv6_UC {
@@ -1617,14 +1631,6 @@ func (server *BgpServer) handleGrpc(grpcReq *GrpcRequest) {
 							}
 						}
 					}
-				} else if dst.LongerPrefixes {
-					_, prefix, _ := net.ParseCIDR(key)
-
-					for _, dst := range rib.Tables[af].GetLongerPrefixDestinations(prefix.String()) {
-						if d := dst.ToApiStruct(id); d != nil {
-							dsts = append(dsts, d)
-						}
-					}
 				}
 			}
 		} else {