policy: add prefix filter

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

1 files changed, 274 insertions, 0 deletions

diff --git a/policy/policy.go b/policy/policy.go
new file mode 100644
index 00000000..9bb4bc8c
--- /dev/null
+++ b/policy/policy.go
@@ -0,0 +1,274 @@
+// Copyright (C) 2014,2015 Nippon Telegraph and Telephone Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package policy
+
+import (
+	"fmt"
+	log "github.com/Sirupsen/logrus"
+	"github.com/osrg/gobgp/config"
+	"github.com/osrg/gobgp/packet"
+	"github.com/osrg/gobgp/table"
+	"net"
+	"strconv"
+	"strings"
+)
+
+type RouteType int
+
+const (
+	ROUTE_TYPE_NONE = iota
+	ROUTE_TYPE_ACCEPT
+	ROUTE_TYPE_REJECT
+)
+
+type MaskLengthRangeType int
+
+const (
+	MASK_LENGTH_RANGE_MIN = iota
+	MASK_LENGTH_RANGE_MAX
+)
+
+type Policy struct {
+	Name       string
+	Statements []Statement
+}
+
+func NewPolicy(name string, pd config.PolicyDefinition, cdf config.DefinedSets) *Policy {
+	cst := pd.StatementList
+	st := make([]Statement, 0)
+	p := &Policy{
+		Name:       name,
+		Statements: st,
+	}
+	for _, cs := range cst {
+		pName := cs.Conditions.MatchPrefixSet
+		npl := make([]Prefix, 0)
+		for _, psl := range cdf.PrefixSetList {
+			if psl.PrefixSetName == pName {
+				for _, ps := range psl.PrefixList {
+					npl = append(npl, NewPrefix(ps.Address, ps.Masklength, ps.MasklengthRange))
+				}
+			}
+		}
+		nName := cs.Conditions.MatchNeighborSet
+		nnl := make([]net.IP, 0)
+		for _, nsl := range cdf.NeighborSetList {
+			if nsl.NeighborSetName == nName {
+				for _, nl := range nsl.NeighborInfoList {
+					nnl = append(nnl, nl.Address)
+				}
+			}
+		}
+		con := Conditions{
+			PrefixList:   npl,
+			NeighborList: nnl,
+		}
+		act := Actions{
+			AcceptRoute: cs.Actions.AcceptRoute,
+			RejectRoute: cs.Actions.RejectRoute,
+		}
+		s := Statement{
+			Name:       cs.Name,
+			Conditions: con,
+			Actions:    act,
+		}
+		st = append(st, s)
+	}
+	p.Statements = st
+	return p
+}
+
+type Statement struct {
+	Name       string
+	Conditions Conditions
+	Actions    Actions
+}
+
+type Conditions struct {
+	//CallPolicy       string
+	PrefixList   []Prefix
+	NeighborList []net.IP
+}
+
+type Actions struct {
+	AcceptRoute bool
+	RejectRoute bool
+}
+
+type Prefix struct {
+	Address         net.IP
+	Masklength      uint8
+	MasklengthRange map[MaskLengthRangeType]uint8
+}
+
+func NewPrefix(addr net.IP, maskLen uint8, maskRange string) Prefix {
+	mlr := make(map[MaskLengthRangeType]uint8)
+	p := Prefix{
+		Address:         addr,
+		Masklength:      maskLen,
+		MasklengthRange: make(map[MaskLengthRangeType]uint8),
+	}
+	idx := strings.Index(maskRange, "..")
+	if idx == -1 {
+		log.WithFields(log.Fields{
+			"Topic":      "Policy",
+			"Address":    addr,
+			"Masklength": maskLen,
+		}).Warn("mask length range of condition is invalid format")
+		return p
+	}
+	if idx != 0 {
+		min, e := strconv.ParseUint(maskRange[:idx], 10, 8)
+		if e != nil {
+			log.WithFields(log.Fields{
+				"Topic": "Policy",
+				"Error": e,
+			}).Error("failed to parse the min length of mask length range")
+			return p
+		}
+		mlr[MASK_LENGTH_RANGE_MIN] = uint8(min)
+	}
+	if idx != len(maskRange)-1 {
+		max, e := strconv.ParseUint(maskRange[idx+2:], 10, 8)
+		if e != nil {
+			log.WithFields(log.Fields{
+				"Topic": "Policy",
+				"Error": e,
+			}).Error("failed to parse the max length of mask length range")
+			return p
+		}
+		mlr[MASK_LENGTH_RANGE_MAX] = uint8(max)
+	}
+	p.MasklengthRange = mlr
+	return p
+}
+
+//compare path and condition of policy
+//and, subsequent comparison skip if that matches the conditions.
+func (p *Policy) Apply(path table.Path) (bool, RouteType, table.Path) {
+	for _, statement := range p.Statements {
+		matchPrefix := false
+		matchNeighbor := false
+		if len(statement.Conditions.PrefixList) <= 0 && len(statement.Conditions.NeighborList) <= 0 {
+			return false, ROUTE_TYPE_NONE, nil
+		} else if len(statement.Conditions.PrefixList) <= 0 && len(statement.Conditions.NeighborList) > 0 {
+			matchPrefix = true
+			matchNeighbor = statement.compareNeighbor(path)
+		} else if len(statement.Conditions.NeighborList) <= 0 && len(statement.Conditions.PrefixList) > 0 {
+			matchPrefix = statement.comparePrefix(path)
+			matchNeighbor = true
+		} else {
+			matchPrefix = statement.comparePrefix(path)
+			matchNeighbor = statement.compareNeighbor(path)
+		}
+		an := statement.Actions
+
+		//if match the one of the prefix list and match to any of tye neighbor list,
+		//determines that matches the conditions of the statement
+		if matchPrefix && matchNeighbor {
+			if an.AcceptRoute {
+				// accept the path
+				// and return the path updated in acction definition
+				// TODO update path using acction definition.
+				//      implementation waiting for yang.
+				newPath := path
+				log.WithFields(log.Fields{
+					"Topic":   "Policy",
+					"Type":    "ROUTE_ACCEPT",
+					"OldPath": path,
+					"NewPath": newPath,
+				}).Debug("Apply policy to path")
+				return true, ROUTE_TYPE_ACCEPT, newPath
+
+			} else {
+				// reject the path
+				// and return the path updated in acction definition
+				// TODO update path using acction definition.
+				//      implementation waiting for yang.
+				newPath := path
+				log.WithFields(log.Fields{
+					"Topic":   "Policy",
+					"Type":    "ROUTE_REJECT",
+					"OldPath": path,
+					"NewPath": newPath,
+				}).Debug("Apply policy to path")
+				return true, ROUTE_TYPE_REJECT, nil
+			}
+		}
+	}
+	return false, ROUTE_TYPE_NONE, nil
+}
+
+//compare prefix of condition policy and nlri of path
+//and, subsequent comparison skip if that matches the conditions.
+func (s *Statement) comparePrefix(path table.Path) bool {
+	for _, cp := range s.Conditions.PrefixList {
+		if IpPrefixCalcurate(path, cp) {
+			return true
+		}
+	}
+	return false
+}
+
+//compare neighbor ipaddress of condition policy and source of path
+//and, subsequent comparison skip if that matches the conditions.
+func (s *Statement) compareNeighbor(path table.Path) bool {
+	for _, neighbor := range s.Conditions.NeighborList {
+		cAddr := neighbor
+		pAddr := path.GetSource().Address
+		if pAddr.Equal(cAddr) {
+			return true
+		}
+
+	}
+	return false
+}
+
+func IpPrefixCalcurate(path table.Path, cPrefix Prefix) bool {
+	pAddr := path.GetNlri().(*bgp.NLRInfo).IPAddrPrefix.Prefix
+	pMaskLen := path.GetNlri().(*bgp.NLRInfo).IPAddrPrefix.Length
+	cp := fmt.Sprintf("%s/%d", cPrefix.Address, cPrefix.Masklength)
+	rMin, okMin := cPrefix.MasklengthRange[MASK_LENGTH_RANGE_MIN]
+	rMax, okMax := cPrefix.MasklengthRange[MASK_LENGTH_RANGE_MAX]
+
+	//TODO add conditional processing by RouteFamily.
+
+	if !okMin && !okMax {
+		if pAddr.Equal(cPrefix.Address) && pMaskLen == cPrefix.Masklength {
+			return true
+		} else {
+			return false
+		}
+	} else if !okMin {
+		rMin = uint8(0)
+	} else if !okMax {
+		rMax = uint8(32)
+	}
+
+	_, ipNet, e := net.ParseCIDR(cp)
+	if e != nil {
+		log.WithFields(log.Fields{
+			"Topic":  "Policy",
+			"Prefix": ipNet,
+			"Error":  e,
+		}).Error("failed to parse the prefix of condition")
+		return false
+	}
+	if ipNet.Contains(pAddr) && (rMin <= pMaskLen && pMaskLen <= rMax) {
+		return true
+	}
+	return false
+}