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Kevin KrakauerandgVisor bot
ef88b30bff
The important change here is in tcpip/tcpip.go, where tcpip.Address is defined. The rest is updating uses of tcpip.Address. This is preparation for netip.Addr or []byte based addresses, which should save us a bunch of allocations. Currently, we allocate every time we want to, say, get a tcpip.Address from a header. This is because the header is a byte slice, but Address is a string. Strings are immutable, so Go allocates and copies. PiperOrigin-RevId: 532284732
125 lines
4.0 KiB
Go
125 lines
4.0 KiB
Go
// Copyright 2022 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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"bytes"
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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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func mldv2AndIGMPv3QuerierQueryCodeToInterval(code uint8) time.Duration {
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// MLDv2: As per RFC 3810 section 5.1.19,
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//
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// The Querier's Query Interval Code field specifies the [Query
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// Interval] used by the Querier. The actual interval, called the
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// Querier's Query Interval (QQI), is represented in units of seconds,
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// and is derived from the Querier's Query Interval Code as follows:
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//
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// If QQIC < 128, QQI = QQIC
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//
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// If QQIC >= 128, QQIC represents a floating-point value as follows:
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//
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// 0 1 2 3 4 5 6 7
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// +-+-+-+-+-+-+-+-+
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// |1| exp | mant |
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// +-+-+-+-+-+-+-+-+
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//
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// QQI = (mant | 0x10) << (exp + 3)
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//
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// Multicast routers that are not the current Querier adopt the QQI
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// value from the most recently received Query as their own [Query
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// Interval] value, unless that most recently received QQI was zero, in
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// which case the receiving routers use the default [Query Interval]
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// value specified in section 9.2.
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//
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// IGMPv3: As per RFC 3376 section 4.1.7,
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//
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// The Querier's Query Interval Code field specifies the [Query
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// Interval] used by the querier. The actual interval, called the
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// Querier's Query Interval (QQI), is represented in units of seconds
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// and is derived from the Querier's Query Interval Code as follows:
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//
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// If QQIC < 128, QQI = QQIC
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//
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// If QQIC >= 128, QQIC represents a floating-point value as follows:
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//
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// 0 1 2 3 4 5 6 7
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// +-+-+-+-+-+-+-+-+
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// |1| exp | mant |
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// +-+-+-+-+-+-+-+-+
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//
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// QQI = (mant | 0x10) << (exp + 3)
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//
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// Multicast routers that are not the current querier adopt the QQI
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// value from the most recently received Query as their own [Query
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// Interval] value, unless that most recently received QQI was zero, in
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// which case the receiving routers use the default [Query Interval]
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// value specified in section 8.2.
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interval := time.Duration(code)
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if interval < 128 {
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return interval * time.Second
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}
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const expMask = 0b111
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const mantBits = 4
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mant := interval & ((1 << mantBits) - 1)
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exp := (interval >> mantBits) & expMask
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return (mant | 0x10) << (exp + 3) * time.Second
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}
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// MakeAddressIterator returns an AddressIterator.
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func MakeAddressIterator(addressSize int, buf *bytes.Buffer) AddressIterator {
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return AddressIterator{addressSize: addressSize, buf: buf}
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}
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// AddressIterator is an iterator over IPv6 addresses.
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type AddressIterator struct {
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addressSize int
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buf *bytes.Buffer
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}
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// Done indicates that the iterator has been exhausted/has no more elements.
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func (it *AddressIterator) Done() bool {
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return it.buf.Len() == 0
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}
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// Next returns the next address in the iterator.
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//
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// Returns false if the iterator has been exhausted.
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func (it *AddressIterator) Next() (tcpip.Address, bool) {
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if it.Done() {
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var emptyAddress tcpip.Address
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return emptyAddress, false
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}
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b := it.buf.Next(it.addressSize)
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if len(b) != it.addressSize {
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panic(fmt.Sprintf("got len(buf.Next(%d)) = %d, want = %d", it.addressSize, len(b), it.addressSize))
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}
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return tcpip.AddrFromSlice(b), true
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}
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func makeAddressIterator(b []byte, expectedAddresses uint16, addressSize int) (AddressIterator, bool) {
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expectedLen := int(expectedAddresses) * addressSize
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if len(b) < expectedLen {
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return AddressIterator{}, false
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}
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return MakeAddressIterator(addressSize, bytes.NewBuffer(b[:expectedLen])), true
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}
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