1 files changed, 97 insertions, 0 deletions
diff --git a/table/table.go b/table/table.go
index b1ec94a1..bad0e824 100644
--- a/table/table.go
+++ b/table/table.go
@@ -16,6 +16,7 @@
 package table
 
 import (
+	"fmt"
 	"net"
 	"sort"
 
@@ -24,6 +25,26 @@ import (
 	"github.com/osrg/gobgp/packet/bgp"
 )
 
+type LookupOption uint8
+
+const (
+	LOOKUP_EXACT LookupOption = iota
+	LOOKUP_LONGER
+	LOOKUP_SHORTER
+)
+
+type LookupPrefix struct {
+	Prefix string
+	LookupOption
+}
+
+type TableSelectOption struct {
+	ID             string
+	LookupPrefixes []*LookupPrefix
+	VRF            *Vrf
+	adj            bool
+}
+
 type Table struct {
 	routeFamily  bgp.RouteFamily
 	destinations map[string]*Destination
@@ -287,3 +308,79 @@ func (t *Table) GetKnownPathList(id string) []*Path {
 	}
 	return paths
 }
+
+func (t *Table) Select(option ...TableSelectOption) (*Table, error) {
+	id := GLOBAL_RIB_NAME
+	var vrf *Vrf
+	adj := false
+	prefixes := make([]*LookupPrefix, 0, len(option))
+	for _, o := range option {
+		if o.ID != "" {
+			id = o.ID
+		}
+		if o.VRF != nil {
+			vrf = o.VRF
+		}
+		adj = o.adj
+		prefixes = append(prefixes, o.LookupPrefixes...)
+	}
+	dsts := make(map[string]*Destination)
+	if (t.routeFamily == bgp.RF_IPv4_UC || t.routeFamily == bgp.RF_IPv6_UC) && len(prefixes) > 0 {
+		f := func(id, key string) (bool, error) {
+			if dst := t.GetDestination(key); dst != nil {
+				if d := dst.Select(DestinationSelectOption{ID: id, adj: adj}); d != nil {
+					dsts[key] = d
+					return true, nil
+				}
+			}
+			return false, nil
+		}
+		for _, p := range prefixes {
+			key := p.Prefix
+			switch p.LookupOption {
+			case LOOKUP_LONGER:
+				ds, err := t.GetLongerPrefixDestinations(key)
+				if err != nil {
+					return nil, err
+				}
+				for _, dst := range ds {
+					dsts[dst.GetNlri().String()] = dst.Select(DestinationSelectOption{ID: id, adj: adj})
+				}
+			case LOOKUP_SHORTER:
+				_, prefix, err := net.ParseCIDR(key)
+				if err != nil {
+					return nil, err
+				}
+				ones, bits := prefix.Mask.Size()
+				for i := ones; i > 0; i-- {
+					prefix.Mask = net.CIDRMask(i, bits)
+					f(id, prefix.String())
+				}
+			default:
+				if _, err := f(id, key); err != nil {
+					if host := net.ParseIP(key); host != nil {
+						masklen := 32
+						if t.routeFamily == bgp.RF_IPv6_UC {
+							masklen = 128
+						}
+						for i := masklen; i > 0; i-- {
+							if y, _ := f(id, fmt.Sprintf("%s/%d", key, i)); y {
+								break
+							}
+						}
+					}
+				}
+			}
+		}
+	} else {
+		for k, dst := range t.GetDestinations() {
+			if d := dst.Select(DestinationSelectOption{ID: id, VRF: vrf, adj: adj}); d != nil {
+				dsts[k] = d
+			}
+		}
+	}
+	return &Table{
+		routeFamily:  t.routeFamily,
+		destinations: dsts,
+	}, nil
+}