Add types to parse MLD messages
Preparing for upcoming CLs that add MLD functionality. Bug #4861 Test: header.TestMLD PiperOrigin-RevId: 343391556
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@ -16,6 +16,7 @@ go_library(
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"ipv6.go",
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"ipv6_extension_headers.go",
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"ipv6_fragment.go",
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"mld.go",
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"ndp_neighbor_advert.go",
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"ndp_neighbor_solicit.go",
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"ndp_options.go",
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@ -58,6 +59,7 @@ go_test(
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srcs = [
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"eth_test.go",
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"ipv6_extension_headers_test.go",
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"mld_test.go",
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"ndp_test.go",
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],
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library = ":header",
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@ -0,0 +1,96 @@
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// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package header
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import (
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"encoding/binary"
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"fmt"
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"time"
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"gvisor.dev/gvisor/pkg/tcpip"
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)
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const (
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// mldMaximumResponseDelayOffset is the offset to the Maximum Response Delay
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// field within MLD.
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mldMaximumResponseDelayOffset = 0
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// mldMulticastAddressOffset is the offset to the Multicast Address field
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// within MLD.
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mldMulticastAddressOffset = 4
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)
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// MLD is a Multicast Listener Discovery message in an ICMPv6 packet.
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//
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// MLD will only contain the body of an ICMPv6 packet.
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//
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// As per RFC 2710 section 3, MLD messages have the following format (MLD only
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// holds the bytes after the first four bytes in the diagram below):
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//
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// 0 1 2 3
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// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Type | Code | Checksum |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Maximum Response Delay | Reserved |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | |
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// + +
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// | |
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// + Multicast Address +
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// | |
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// + +
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// | |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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type MLD []byte
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// MaximumResponseDelay returns the Maximum Response Delay.
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func (m MLD) MaximumResponseDelay() time.Duration {
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// As per RFC 2710 section 3.4:
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//
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// The Maximum Response Delay field is meaningful only in Query
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// messages, and specifies the maximum allowed delay before sending a
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// responding Report, in units of milliseconds. In all other messages,
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// it is set to zero by the sender and ignored by receivers.
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return time.Duration(binary.BigEndian.Uint16(m[mldMaximumResponseDelayOffset:])) * time.Millisecond
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}
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// SetMaximumResponseDelay sets the Maximum Response Delay field.
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//
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// maxRespDelayMS is the value in milliseconds.
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func (m MLD) SetMaximumResponseDelay(maxRespDelayMS uint16) {
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binary.BigEndian.PutUint16(m[mldMaximumResponseDelayOffset:], maxRespDelayMS)
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}
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// MulticastAddress returns the Multicast Address.
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func (m MLD) MulticastAddress() tcpip.Address {
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// As per RFC 2710 section 3.5:
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//
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// In a Query message, the Multicast Address field is set to zero when
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// sending a General Query, and set to a specific IPv6 multicast address
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// when sending a Multicast-Address-Specific Query.
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//
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// In a Report or Done message, the Multicast Address field holds a
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// specific IPv6 multicast address to which the message sender is
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// listening or is ceasing to listen, respectively.
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return tcpip.Address(m[mldMulticastAddressOffset:][:IPv6AddressSize])
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}
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// SetMulticastAddress sets the Multicast Address field.
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func (m MLD) SetMulticastAddress(multicastAddress tcpip.Address) {
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if n := copy(m[mldMulticastAddressOffset:], multicastAddress); n != IPv6AddressSize {
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panic(fmt.Sprintf("copied %d bytes, expected to copy %d bytes", n, IPv6AddressSize))
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}
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}
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@ -0,0 +1,61 @@
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// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package header
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import (
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"encoding/binary"
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"testing"
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"time"
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"gvisor.dev/gvisor/pkg/tcpip"
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)
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func TestMLD(t *testing.T) {
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b := []byte{
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// Maximum Response Delay
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0, 0,
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// Reserved
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0, 0,
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// MulticastAddress
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1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6,
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}
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const maxRespDelay = 513
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binary.BigEndian.PutUint16(b, maxRespDelay)
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mld := MLD(b)
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if got, want := mld.MaximumResponseDelay(), maxRespDelay*time.Millisecond; got != want {
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t.Errorf("got mld.MaximumResponseDelay() = %s, want = %s", got, want)
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}
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const newMaxRespDelay = 1234
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mld.SetMaximumResponseDelay(newMaxRespDelay)
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if got, want := mld.MaximumResponseDelay(), newMaxRespDelay*time.Millisecond; got != want {
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t.Errorf("got mld.MaximumResponseDelay() = %s, want = %s", got, want)
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}
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if got, want := mld.MulticastAddress(), tcpip.Address([]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6}); got != want {
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t.Errorf("got mld.MulticastAddress() = %s, want = %s", got, want)
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}
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multicastAddress := tcpip.Address([]byte{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0})
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mld.SetMulticastAddress(multicastAddress)
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if got := mld.MulticastAddress(); got != multicastAddress {
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t.Errorf("got mld.MulticastAddress() = %s, want = %s", got, multicastAddress)
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}
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}
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