Add a type to represent the NDP Router Advertisement message.
This change is in preparation for NDP Router Discovery where the stack will need
to handle NDP Router Advertisments.
Tests: Test that given an NDP Router Advertisement buffer (body of an ICMPv6
packet, correct values are returned by the field getters).
PiperOrigin-RevId: 276146817
diff --git a/tcpip/header/ndp_neighbor_advert.go b/tcpip/header/ndp_neighbor_advert.go
index 3abc5e1..6fbbf77 100644
--- a/tcpip/header/ndp_neighbor_advert.go
+++ b/tcpip/header/ndp_neighbor_advert.go
@@ -18,6 +18,8 @@
// NDPNeighborAdvert is an NDP Neighbor Advertisement message. It will
// only contain the body of an ICMPv6 packet.
+//
+// See RFC 4861 section 4.4 for more details.
type NDPNeighborAdvert []byte
const (
diff --git a/tcpip/header/ndp_neighbor_solicit.go b/tcpip/header/ndp_neighbor_solicit.go
index 2637759..d5a3208 100644
--- a/tcpip/header/ndp_neighbor_solicit.go
+++ b/tcpip/header/ndp_neighbor_solicit.go
@@ -18,6 +18,8 @@
// NDPNeighborSolicit is an NDP Neighbor Solicitation message. It will only
// contain the body of an ICMPv6 packet.
+//
+// See RFC 4861 section 4.3 for more details.
type NDPNeighborSolicit []byte
const (
diff --git a/tcpip/header/ndp_router_advert.go b/tcpip/header/ndp_router_advert.go
new file mode 100644
index 0000000..bf76108
--- /dev/null
+++ b/tcpip/header/ndp_router_advert.go
@@ -0,0 +1,112 @@
+// Copyright 2019 The gVisor Authors.
+//
+// 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 header
+
+import (
+ "encoding/binary"
+ "time"
+)
+
+// NDPRouterAdvert is an NDP Router Advertisement message. It will only contain
+// the body of an ICMPv6 packet.
+//
+// See RFC 4861 section 4.2 for more details.
+type NDPRouterAdvert []byte
+
+const (
+ // NDPRAMinimumSize is the minimum size of a valid NDP Router
+ // Advertisement message (body of an ICMPv6 packet).
+ NDPRAMinimumSize = 12
+
+ // ndpRACurrHopLimitOffset is the byte of the Curr Hop Limit field
+ // within an NDPRouterAdvert.
+ ndpRACurrHopLimitOffset = 0
+
+ // ndpRAFlagsOffset is the byte with the NDP RA bit-fields/flags
+ // within an NDPRouterAdvert.
+ ndpRAFlagsOffset = 1
+
+ // ndpRAManagedAddrConfFlagMask is the mask of the Managed Address
+ // Configuration flag within the bit-field/flags byte of an
+ // NDPRouterAdvert.
+ ndpRAManagedAddrConfFlagMask = (1 << 7)
+
+ // ndpRAOtherConfFlagMask is the mask of the Other Configuration flag
+ // within the bit-field/flags byte of an NDPRouterAdvert.
+ ndpRAOtherConfFlagMask = (1 << 6)
+
+ // ndpRARouterLifetimeOffset is the start of the 2-byte Router Lifetime
+ // field within an NDPRouterAdvert.
+ ndpRARouterLifetimeOffset = 2
+
+ // ndpRAReachableTimeOffset is the start of the 4-byte Reachable Time
+ // field within an NDPRouterAdvert.
+ ndpRAReachableTimeOffset = 4
+
+ // ndpRARetransTimerOffset is the start of the 4-byte Retrans Timer
+ // field within an NDPRouterAdvert.
+ ndpRARetransTimerOffset = 8
+
+ // ndpRAOptionsOffset is the start of the NDP options in an
+ // NDPRouterAdvert.
+ ndpRAOptionsOffset = 12
+)
+
+// CurrHopLimit returns the value of the Curr Hop Limit field.
+func (b NDPRouterAdvert) CurrHopLimit() uint8 {
+ return b[ndpRACurrHopLimitOffset]
+}
+
+// ManagedAddrConfFlag returns the value of the Managed Address Configuration
+// flag.
+func (b NDPRouterAdvert) ManagedAddrConfFlag() bool {
+ return b[ndpRAFlagsOffset]&ndpRAManagedAddrConfFlagMask != 0
+}
+
+// OtherConfFlag returns the value of the Other Configuration flag.
+func (b NDPRouterAdvert) OtherConfFlag() bool {
+ return b[ndpRAFlagsOffset]&ndpRAOtherConfFlagMask != 0
+}
+
+// RouterLifetime returns the lifetime associated with the default router. A
+// value of 0 means the source of the Router Advertisement is not a default
+// router and SHOULD NOT appear on the default router list. Note, a value of 0
+// only means that the router should not be used as a default router, it does
+// not apply to other information contained in the Router Advertisement.
+func (b NDPRouterAdvert) RouterLifetime() time.Duration {
+ // The field is the time in seconds, as per RFC 4861 section 4.2.
+ return time.Second * time.Duration(binary.BigEndian.Uint16(b[ndpRARouterLifetimeOffset:]))
+}
+
+// ReachableTime returns the time that a node assumes a neighbor is reachable
+// after having received a reachability confirmation. A value of 0 means
+// that it is unspecified by the source of the Router Advertisement message.
+func (b NDPRouterAdvert) ReachableTime() time.Duration {
+ // The field is the time in milliseconds, as per RFC 4861 section 4.2.
+ return time.Millisecond * time.Duration(binary.BigEndian.Uint32(b[ndpRAReachableTimeOffset:]))
+}
+
+// RetransTimer returns the time between retransmitted Neighbor Solicitation
+// messages. A value of 0 means that it is unspecified by the source of the
+// Router Advertisement message.
+func (b NDPRouterAdvert) RetransTimer() time.Duration {
+ // The field is the time in milliseconds, as per RFC 4861 section 4.2.
+ return time.Millisecond * time.Duration(binary.BigEndian.Uint32(b[ndpRARetransTimerOffset:]))
+}
+
+// Options returns an NDPOptions of the the options body.
+func (b NDPRouterAdvert) Options() NDPOptions {
+ return NDPOptions(b[ndpRAOptionsOffset:])
+}
diff --git a/tcpip/header/ndp_test.go b/tcpip/header/ndp_test.go
index 7d66e70..aee6793 100644
--- a/tcpip/header/ndp_test.go
+++ b/tcpip/header/ndp_test.go
@@ -17,6 +17,7 @@
import (
"bytes"
"testing"
+ "time"
"github.com/google/netstack/tcpip"
)
@@ -117,6 +118,40 @@
}
}
+func TestNDPRouterAdvert(t *testing.T) {
+ b := []byte{
+ 64, 128, 1, 2,
+ 3, 4, 5, 6,
+ 7, 8, 9, 10,
+ }
+
+ ra := NDPRouterAdvert(b)
+
+ if got := ra.CurrHopLimit(); got != 64 {
+ t.Fatalf("got ra.CurrHopLimit = %d, want = 64", got)
+ }
+
+ if got := ra.ManagedAddrConfFlag(); !got {
+ t.Fatalf("got ManagedAddrConfFlag = false, want = true")
+ }
+
+ if got := ra.OtherConfFlag(); got {
+ t.Fatalf("got OtherConfFlag = true, want = false")
+ }
+
+ if got, want := ra.RouterLifetime(), time.Second*258; got != want {
+ t.Fatalf("got ra.RouterLifetime = %d, want = %d", got, want)
+ }
+
+ if got, want := ra.ReachableTime(), time.Millisecond*50595078; got != want {
+ t.Fatalf("got ra.ReachableTime = %d, want = %d", got, want)
+ }
+
+ if got, want := ra.RetransTimer(), time.Millisecond*117967114; got != want {
+ t.Fatalf("got ra.RetransTimer = %d, want = %d", got, want)
+ }
+}
+
// TestNDPTargetLinkLayerAddressOptionSerialize tests serializing a
// NDPTargetLinkLayerAddressOption.
func TestNDPTargetLinkLayerAddressOptionSerialize(t *testing.T) {
