1 files changed, 221 insertions, 0 deletions
diff --git a/packet/bgp/validate.go b/packet/bgp/validate.go
new file mode 100644
index 00000000..73697c4d
--- /dev/null
+++ b/packet/bgp/validate.go
@@ -0,0 +1,221 @@
+package bgp
+
+import (
+	"encoding/binary"
+	"fmt"
+	"net"
+	"strconv"
+)
+
+// Validator for BGPUpdate
+func ValidateUpdateMsg(m *BGPUpdate, rfs map[RouteFamily]bool, doConfedCheck bool) (bool, error) {
+	eCode := uint8(BGP_ERROR_UPDATE_MESSAGE_ERROR)
+	eSubCodeAttrList := uint8(BGP_ERROR_SUB_MALFORMED_ATTRIBUTE_LIST)
+	eSubCodeMissing := uint8(BGP_ERROR_SUB_MISSING_WELL_KNOWN_ATTRIBUTE)
+
+	if len(m.NLRI) > 0 || len(m.WithdrawnRoutes) > 0 {
+		if _, ok := rfs[RF_IPv4_UC]; !ok {
+			return false, NewMessageError(0, 0, nil, fmt.Sprintf("Address-family rf %d not avalible for session", RF_IPv4_UC))
+		}
+	}
+
+	seen := make(map[BGPAttrType]PathAttributeInterface)
+	// check path attribute
+	for _, a := range m.PathAttributes {
+		// check duplication
+		if _, ok := seen[a.GetType()]; !ok {
+			seen[a.GetType()] = a
+		} else {
+			eMsg := "the path attribute apears twice. Type : " + strconv.Itoa(int(a.GetType()))
+			return false, NewMessageError(eCode, eSubCodeAttrList, nil, eMsg)
+		}
+
+		//check specific path attribute
+		ok, e := ValidateAttribute(a, rfs, doConfedCheck)
+		if !ok {
+			return false, e
+		}
+	}
+
+	if len(m.NLRI) > 0 {
+		// check the existence of well-known mandatory attributes
+		exist := func(attrs []BGPAttrType) (bool, BGPAttrType) {
+			for _, attr := range attrs {
+				_, ok := seen[attr]
+				if !ok {
+					return false, attr
+				}
+			}
+			return true, 0
+		}
+		mandatory := []BGPAttrType{BGP_ATTR_TYPE_ORIGIN, BGP_ATTR_TYPE_AS_PATH, BGP_ATTR_TYPE_NEXT_HOP}
+		if ok, t := exist(mandatory); !ok {
+			eMsg := "well-known mandatory attributes are not present. type : " + strconv.Itoa(int(t))
+			data := []byte{byte(t)}
+			return false, NewMessageError(eCode, eSubCodeMissing, data, eMsg)
+		}
+	}
+	return true, nil
+}
+
+func ValidateAttribute(a PathAttributeInterface, rfs map[RouteFamily]bool, doConfedCheck bool) (bool, error) {
+
+	eCode := uint8(BGP_ERROR_UPDATE_MESSAGE_ERROR)
+	eSubCodeBadOrigin := uint8(BGP_ERROR_SUB_INVALID_ORIGIN_ATTRIBUTE)
+	eSubCodeBadNextHop := uint8(BGP_ERROR_SUB_INVALID_NEXT_HOP_ATTRIBUTE)
+	eSubCodeUnknown := uint8(BGP_ERROR_SUB_UNRECOGNIZED_WELL_KNOWN_ATTRIBUTE)
+	eSubCodeMalformedAspath := uint8(BGP_ERROR_SUB_MALFORMED_AS_PATH)
+
+	checkPrefix := func(l []AddrPrefixInterface) bool {
+		for _, prefix := range l {
+			rf := AfiSafiToRouteFamily(prefix.AFI(), prefix.SAFI())
+			if _, ok := rfs[rf]; !ok {
+				return false
+			}
+		}
+		return true
+	}
+
+	switch p := a.(type) {
+	case *PathAttributeMpUnreachNLRI:
+		rf := AfiSafiToRouteFamily(p.AFI, p.SAFI)
+		if _, ok := rfs[rf]; !ok {
+			return false, NewMessageError(0, 0, nil, fmt.Sprintf("Address-family rf %d not avalible for session", rf))
+		}
+		if checkPrefix(p.Value) == false {
+			return false, NewMessageError(0, 0, nil, fmt.Sprintf("Address-family rf %d not avalible for session", rf))
+		}
+	case *PathAttributeMpReachNLRI:
+		rf := AfiSafiToRouteFamily(p.AFI, p.SAFI)
+		if _, ok := rfs[rf]; !ok {
+			return false, NewMessageError(0, 0, nil, fmt.Sprintf("Address-family rf %d not avalible for session", rf))
+		}
+		if checkPrefix(p.Value) == false {
+			return false, NewMessageError(0, 0, nil, fmt.Sprintf("Address-family rf %d not avalible for session", rf))
+		}
+	case *PathAttributeOrigin:
+		v := uint8(p.Value[0])
+		if v != BGP_ORIGIN_ATTR_TYPE_IGP &&
+			v != BGP_ORIGIN_ATTR_TYPE_EGP &&
+			v != BGP_ORIGIN_ATTR_TYPE_INCOMPLETE {
+			data, _ := a.Serialize()
+			eMsg := "invalid origin attribute. value : " + strconv.Itoa(int(v))
+			return false, NewMessageError(eCode, eSubCodeBadOrigin, data, eMsg)
+		}
+	case *PathAttributeNextHop:
+
+		isZero := func(ip net.IP) bool {
+			res := ip[0] & 0xff
+			return res == 0x00
+		}
+
+		isClassDorE := func(ip net.IP) bool {
+			res := ip[0] & 0xe0
+			return res == 0xe0
+		}
+
+		//check IP address represents host address
+		if p.Value.IsLoopback() || isZero(p.Value) || isClassDorE(p.Value) {
+			eMsg := "invalid nexthop address"
+			data, _ := a.Serialize()
+			return false, NewMessageError(eCode, eSubCodeBadNextHop, data, eMsg)
+		}
+	case *PathAttributeAsPath:
+		if doConfedCheck {
+			for _, paramIf := range p.Value {
+				var segType uint8
+				asParam, y := paramIf.(*As4PathParam)
+				if y {
+					segType = asParam.Type
+				} else {
+					segType = paramIf.(*AsPathParam).Type
+				}
+
+				if segType == BGP_ASPATH_ATTR_TYPE_CONFED_SET || segType == BGP_ASPATH_ATTR_TYPE_CONFED_SEQ {
+					return false, NewMessageError(eCode, eSubCodeMalformedAspath, nil, fmt.Sprintf("segment type confederation(%d) found", segType))
+				}
+			}
+		}
+
+	case *PathAttributeUnknown:
+		if p.getFlags()&BGP_ATTR_FLAG_OPTIONAL == 0 {
+			eMsg := fmt.Sprintf("unrecognized well-known attribute %s", p.GetType())
+			data, _ := a.Serialize()
+			return false, NewMessageError(eCode, eSubCodeUnknown, data, eMsg)
+		}
+	}
+
+	return true, nil
+
+}
+
+// validator for PathAttribute
+func ValidateFlags(t BGPAttrType, flags BGPAttrFlag) (bool, string) {
+
+	/*
+	 * RFC 4271 P.17 For well-known attributes, the Transitive bit MUST be set to 1.
+	 */
+	if flags&BGP_ATTR_FLAG_OPTIONAL == 0 && flags&BGP_ATTR_FLAG_TRANSITIVE == 0 {
+		eMsg := fmt.Sprintf("well-known attribute %s must have transitive flag 1", t)
+		return false, eMsg
+	}
+	/*
+	 * RFC 4271 P.17 For well-known attributes and for optional non-transitive attributes,
+	 * the Partial bit MUST be set to 0.
+	 */
+	if flags&BGP_ATTR_FLAG_OPTIONAL == 0 && flags&BGP_ATTR_FLAG_PARTIAL != 0 {
+		eMsg := fmt.Sprintf("well-known attribute %s must have partial bit 0", t)
+		return false, eMsg
+	}
+	if flags&BGP_ATTR_FLAG_OPTIONAL != 0 && flags&BGP_ATTR_FLAG_TRANSITIVE == 0 && flags&BGP_ATTR_FLAG_PARTIAL != 0 {
+		eMsg := fmt.Sprintf("optional non-transitive attribute %s must have partial bit 0", t)
+		return false, eMsg
+	}
+
+	// check flags are correct
+	if f, ok := pathAttrFlags[t]; ok {
+		if f != flags & ^BGP_ATTR_FLAG_EXTENDED_LENGTH & ^BGP_ATTR_FLAG_PARTIAL {
+			eMsg := fmt.Sprintf("flags are invalid. attribute type: %s, expect: %s, actual: %s", t, f, flags)
+			return false, eMsg
+		}
+	}
+	return true, ""
+}
+
+func ValidateBGPMessage(m *BGPMessage) error {
+	if m.Header.Len > BGP_MAX_MESSAGE_LENGTH {
+		buf := make([]byte, 2)
+		binary.BigEndian.PutUint16(buf, m.Header.Len)
+		return NewMessageError(BGP_ERROR_MESSAGE_HEADER_ERROR, BGP_ERROR_SUB_BAD_MESSAGE_LENGTH, buf, "too long length")
+	}
+
+	return nil
+}
+
+func ValidateOpenMsg(m *BGPOpen, expectedAS uint32) error {
+	if m.Version != 4 {
+		return NewMessageError(BGP_ERROR_OPEN_MESSAGE_ERROR, BGP_ERROR_SUB_UNSUPPORTED_VERSION_NUMBER, nil, fmt.Sprintf("upsuppored version %d", m.Version))
+	}
+
+	as := uint32(m.MyAS)
+	for _, p := range m.OptParams {
+		paramCap, y := p.(*OptionParameterCapability)
+		if !y {
+			continue
+		}
+		for _, c := range paramCap.Capability {
+			if c.Code() == BGP_CAP_FOUR_OCTET_AS_NUMBER {
+				cap := c.(*CapFourOctetASNumber)
+				as = cap.CapValue
+			}
+		}
+	}
+	if as != expectedAS {
+		return NewMessageError(BGP_ERROR_OPEN_MESSAGE_ERROR, BGP_ERROR_SUB_BAD_PEER_AS, nil, fmt.Sprintf("as number mismatch expected %d, received %d", expectedAS, as))
+	}
+
+	if m.HoldTime < 3 && m.HoldTime != 0 {
+		return NewMessageError(BGP_ERROR_OPEN_MESSAGE_ERROR, BGP_ERROR_SUB_UNACCEPTABLE_HOLD_TIME, nil, fmt.Sprintf("unacceptable hold time %d", m.HoldTime))
+	}
+	return nil
+}