mirror of
https://git.zx2c4.com/wireguard-go
synced 2024-11-15 01:05:15 +01:00
d0bc03c707
Implement UDP GSO and GRO for the Linux tun.Device, which is made
possible by virtio extensions in the kernel's TUN driver starting in
v6.2.
secnetperf, a QUIC benchmark utility from microsoft/msquic@8e1eb1a, is
used to demonstrate the effect of this commit between two Linux
computers with i5-12400 CPUs. There is roughly ~13us of round trip
latency between them. secnetperf was invoked with the following command
line options:
-stats:1 -exec:maxtput -test:tput -download:10000 -timed:1 -encrypt:0
The first result is from commit 2e0774f without UDP GSO/GRO on the TUN.
[conn][0x55739a144980] STATS: EcnCapable=0 RTT=3973 us
SendTotalPackets=55859 SendSuspectedLostPackets=61
SendSpuriousLostPackets=59 SendCongestionCount=27
SendEcnCongestionCount=0 RecvTotalPackets=2779122
RecvReorderedPackets=0 RecvDroppedPackets=0
RecvDuplicatePackets=0 RecvDecryptionFailures=0
Result: 3654977571 bytes @ 2922821 kbps (10003.972 ms).
The second result is with UDP GSO/GRO on the TUN.
[conn][0x56493dfd09a0] STATS: EcnCapable=0 RTT=1216 us
SendTotalPackets=165033 SendSuspectedLostPackets=64
SendSpuriousLostPackets=61 SendCongestionCount=53
SendEcnCongestionCount=0 RecvTotalPackets=11845268
RecvReorderedPackets=25267 RecvDroppedPackets=0
RecvDuplicatePackets=0 RecvDecryptionFailures=0
Result: 15574671184 bytes @ 12458214 kbps (10001.222 ms).
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
994 lines
33 KiB
Go
994 lines
33 KiB
Go
/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2017-2023 WireGuard LLC. All Rights Reserved.
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*/
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package tun
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"io"
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"unsafe"
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"golang.org/x/sys/unix"
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"golang.zx2c4.com/wireguard/conn"
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)
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const tcpFlagsOffset = 13
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const (
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tcpFlagFIN uint8 = 0x01
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tcpFlagPSH uint8 = 0x08
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tcpFlagACK uint8 = 0x10
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)
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// virtioNetHdr is defined in the kernel in include/uapi/linux/virtio_net.h. The
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// kernel symbol is virtio_net_hdr.
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type virtioNetHdr struct {
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flags uint8
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gsoType uint8
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hdrLen uint16
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gsoSize uint16
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csumStart uint16
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csumOffset uint16
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}
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func (v *virtioNetHdr) decode(b []byte) error {
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if len(b) < virtioNetHdrLen {
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return io.ErrShortBuffer
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}
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copy(unsafe.Slice((*byte)(unsafe.Pointer(v)), virtioNetHdrLen), b[:virtioNetHdrLen])
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return nil
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}
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func (v *virtioNetHdr) encode(b []byte) error {
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if len(b) < virtioNetHdrLen {
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return io.ErrShortBuffer
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}
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copy(b[:virtioNetHdrLen], unsafe.Slice((*byte)(unsafe.Pointer(v)), virtioNetHdrLen))
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return nil
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}
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const (
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// virtioNetHdrLen is the length in bytes of virtioNetHdr. This matches the
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// shape of the C ABI for its kernel counterpart -- sizeof(virtio_net_hdr).
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virtioNetHdrLen = int(unsafe.Sizeof(virtioNetHdr{}))
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)
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// tcpFlowKey represents the key for a TCP flow.
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type tcpFlowKey struct {
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srcAddr, dstAddr [16]byte
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srcPort, dstPort uint16
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rxAck uint32 // varying ack values should not be coalesced. Treat them as separate flows.
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isV6 bool
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}
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// tcpGROTable holds flow and coalescing information for the purposes of TCP GRO.
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type tcpGROTable struct {
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itemsByFlow map[tcpFlowKey][]tcpGROItem
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itemsPool [][]tcpGROItem
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}
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func newTCPGROTable() *tcpGROTable {
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t := &tcpGROTable{
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itemsByFlow: make(map[tcpFlowKey][]tcpGROItem, conn.IdealBatchSize),
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itemsPool: make([][]tcpGROItem, conn.IdealBatchSize),
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}
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for i := range t.itemsPool {
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t.itemsPool[i] = make([]tcpGROItem, 0, conn.IdealBatchSize)
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}
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return t
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}
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func newTCPFlowKey(pkt []byte, srcAddrOffset, dstAddrOffset, tcphOffset int) tcpFlowKey {
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key := tcpFlowKey{}
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addrSize := dstAddrOffset - srcAddrOffset
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copy(key.srcAddr[:], pkt[srcAddrOffset:dstAddrOffset])
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copy(key.dstAddr[:], pkt[dstAddrOffset:dstAddrOffset+addrSize])
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key.srcPort = binary.BigEndian.Uint16(pkt[tcphOffset:])
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key.dstPort = binary.BigEndian.Uint16(pkt[tcphOffset+2:])
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key.rxAck = binary.BigEndian.Uint32(pkt[tcphOffset+8:])
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key.isV6 = addrSize == 16
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return key
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}
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// lookupOrInsert looks up a flow for the provided packet and metadata,
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// returning the packets found for the flow, or inserting a new one if none
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// is found.
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func (t *tcpGROTable) lookupOrInsert(pkt []byte, srcAddrOffset, dstAddrOffset, tcphOffset, tcphLen, bufsIndex int) ([]tcpGROItem, bool) {
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key := newTCPFlowKey(pkt, srcAddrOffset, dstAddrOffset, tcphOffset)
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items, ok := t.itemsByFlow[key]
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if ok {
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return items, ok
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}
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// TODO: insert() performs another map lookup. This could be rearranged to avoid.
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t.insert(pkt, srcAddrOffset, dstAddrOffset, tcphOffset, tcphLen, bufsIndex)
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return nil, false
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}
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// insert an item in the table for the provided packet and packet metadata.
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func (t *tcpGROTable) insert(pkt []byte, srcAddrOffset, dstAddrOffset, tcphOffset, tcphLen, bufsIndex int) {
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key := newTCPFlowKey(pkt, srcAddrOffset, dstAddrOffset, tcphOffset)
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item := tcpGROItem{
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key: key,
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bufsIndex: uint16(bufsIndex),
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gsoSize: uint16(len(pkt[tcphOffset+tcphLen:])),
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iphLen: uint8(tcphOffset),
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tcphLen: uint8(tcphLen),
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sentSeq: binary.BigEndian.Uint32(pkt[tcphOffset+4:]),
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pshSet: pkt[tcphOffset+tcpFlagsOffset]&tcpFlagPSH != 0,
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}
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items, ok := t.itemsByFlow[key]
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if !ok {
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items = t.newItems()
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}
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items = append(items, item)
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t.itemsByFlow[key] = items
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}
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func (t *tcpGROTable) updateAt(item tcpGROItem, i int) {
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items, _ := t.itemsByFlow[item.key]
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items[i] = item
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}
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func (t *tcpGROTable) deleteAt(key tcpFlowKey, i int) {
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items, _ := t.itemsByFlow[key]
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items = append(items[:i], items[i+1:]...)
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t.itemsByFlow[key] = items
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}
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// tcpGROItem represents bookkeeping data for a TCP packet during the lifetime
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// of a GRO evaluation across a vector of packets.
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type tcpGROItem struct {
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key tcpFlowKey
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sentSeq uint32 // the sequence number
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bufsIndex uint16 // the index into the original bufs slice
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numMerged uint16 // the number of packets merged into this item
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gsoSize uint16 // payload size
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iphLen uint8 // ip header len
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tcphLen uint8 // tcp header len
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pshSet bool // psh flag is set
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}
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func (t *tcpGROTable) newItems() []tcpGROItem {
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var items []tcpGROItem
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items, t.itemsPool = t.itemsPool[len(t.itemsPool)-1], t.itemsPool[:len(t.itemsPool)-1]
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return items
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}
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func (t *tcpGROTable) reset() {
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for k, items := range t.itemsByFlow {
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items = items[:0]
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t.itemsPool = append(t.itemsPool, items)
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delete(t.itemsByFlow, k)
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}
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}
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// udpFlowKey represents the key for a UDP flow.
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type udpFlowKey struct {
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srcAddr, dstAddr [16]byte
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srcPort, dstPort uint16
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isV6 bool
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}
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// udpGROTable holds flow and coalescing information for the purposes of UDP GRO.
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type udpGROTable struct {
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itemsByFlow map[udpFlowKey][]udpGROItem
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itemsPool [][]udpGROItem
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}
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func newUDPGROTable() *udpGROTable {
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u := &udpGROTable{
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itemsByFlow: make(map[udpFlowKey][]udpGROItem, conn.IdealBatchSize),
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itemsPool: make([][]udpGROItem, conn.IdealBatchSize),
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}
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for i := range u.itemsPool {
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u.itemsPool[i] = make([]udpGROItem, 0, conn.IdealBatchSize)
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}
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return u
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}
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func newUDPFlowKey(pkt []byte, srcAddrOffset, dstAddrOffset, udphOffset int) udpFlowKey {
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key := udpFlowKey{}
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addrSize := dstAddrOffset - srcAddrOffset
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copy(key.srcAddr[:], pkt[srcAddrOffset:dstAddrOffset])
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copy(key.dstAddr[:], pkt[dstAddrOffset:dstAddrOffset+addrSize])
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key.srcPort = binary.BigEndian.Uint16(pkt[udphOffset:])
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key.dstPort = binary.BigEndian.Uint16(pkt[udphOffset+2:])
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key.isV6 = addrSize == 16
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return key
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}
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// lookupOrInsert looks up a flow for the provided packet and metadata,
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// returning the packets found for the flow, or inserting a new one if none
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// is found.
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func (u *udpGROTable) lookupOrInsert(pkt []byte, srcAddrOffset, dstAddrOffset, udphOffset, bufsIndex int) ([]udpGROItem, bool) {
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key := newUDPFlowKey(pkt, srcAddrOffset, dstAddrOffset, udphOffset)
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items, ok := u.itemsByFlow[key]
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if ok {
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return items, ok
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}
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// TODO: insert() performs another map lookup. This could be rearranged to avoid.
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u.insert(pkt, srcAddrOffset, dstAddrOffset, udphOffset, bufsIndex, false)
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return nil, false
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}
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// insert an item in the table for the provided packet and packet metadata.
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func (u *udpGROTable) insert(pkt []byte, srcAddrOffset, dstAddrOffset, udphOffset, bufsIndex int, cSumKnownInvalid bool) {
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key := newUDPFlowKey(pkt, srcAddrOffset, dstAddrOffset, udphOffset)
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item := udpGROItem{
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key: key,
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bufsIndex: uint16(bufsIndex),
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gsoSize: uint16(len(pkt[udphOffset+udphLen:])),
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iphLen: uint8(udphOffset),
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cSumKnownInvalid: cSumKnownInvalid,
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}
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items, ok := u.itemsByFlow[key]
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if !ok {
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items = u.newItems()
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}
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items = append(items, item)
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u.itemsByFlow[key] = items
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}
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func (u *udpGROTable) updateAt(item udpGROItem, i int) {
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items, _ := u.itemsByFlow[item.key]
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items[i] = item
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}
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// udpGROItem represents bookkeeping data for a UDP packet during the lifetime
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// of a GRO evaluation across a vector of packets.
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type udpGROItem struct {
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key udpFlowKey
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bufsIndex uint16 // the index into the original bufs slice
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numMerged uint16 // the number of packets merged into this item
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gsoSize uint16 // payload size
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iphLen uint8 // ip header len
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cSumKnownInvalid bool // UDP header checksum validity; a false value DOES NOT imply valid, just unknown.
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}
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func (u *udpGROTable) newItems() []udpGROItem {
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var items []udpGROItem
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items, u.itemsPool = u.itemsPool[len(u.itemsPool)-1], u.itemsPool[:len(u.itemsPool)-1]
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return items
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}
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func (u *udpGROTable) reset() {
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for k, items := range u.itemsByFlow {
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items = items[:0]
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u.itemsPool = append(u.itemsPool, items)
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delete(u.itemsByFlow, k)
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}
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}
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// canCoalesce represents the outcome of checking if two TCP packets are
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// candidates for coalescing.
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type canCoalesce int
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const (
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coalescePrepend canCoalesce = -1
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coalesceUnavailable canCoalesce = 0
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coalesceAppend canCoalesce = 1
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)
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// ipHeadersCanCoalesce returns true if the IP headers found in pktA and pktB
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// meet all requirements to be merged as part of a GRO operation, otherwise it
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// returns false.
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func ipHeadersCanCoalesce(pktA, pktB []byte) bool {
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if len(pktA) < 9 || len(pktB) < 9 {
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return false
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}
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if pktA[0]>>4 == 6 {
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if pktA[0] != pktB[0] || pktA[1]>>4 != pktB[1]>>4 {
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// cannot coalesce with unequal Traffic class values
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return false
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}
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if pktA[7] != pktB[7] {
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// cannot coalesce with unequal Hop limit values
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return false
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}
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} else {
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if pktA[1] != pktB[1] {
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// cannot coalesce with unequal ToS values
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return false
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}
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if pktA[6]>>5 != pktB[6]>>5 {
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// cannot coalesce with unequal DF or reserved bits. MF is checked
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// further up the stack.
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return false
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}
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if pktA[8] != pktB[8] {
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// cannot coalesce with unequal TTL values
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return false
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}
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}
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return true
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}
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// udpPacketsCanCoalesce evaluates if pkt can be coalesced with the packet
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// described by item. iphLen and gsoSize describe pkt. bufs is the vector of
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// packets involved in the current GRO evaluation. bufsOffset is the offset at
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// which packet data begins within bufs.
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func udpPacketsCanCoalesce(pkt []byte, iphLen uint8, gsoSize uint16, item udpGROItem, bufs [][]byte, bufsOffset int) canCoalesce {
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pktTarget := bufs[item.bufsIndex][bufsOffset:]
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if !ipHeadersCanCoalesce(pkt, pktTarget) {
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return coalesceUnavailable
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}
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if len(pktTarget[iphLen+udphLen:])%int(item.gsoSize) != 0 {
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// A smaller than gsoSize packet has been appended previously.
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// Nothing can come after a smaller packet on the end.
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return coalesceUnavailable
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}
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if gsoSize > item.gsoSize {
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// We cannot have a larger packet following a smaller one.
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return coalesceUnavailable
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}
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return coalesceAppend
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}
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// tcpPacketsCanCoalesce evaluates if pkt can be coalesced with the packet
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// described by item. This function makes considerations that match the kernel's
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// GRO self tests, which can be found in tools/testing/selftests/net/gro.c.
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func tcpPacketsCanCoalesce(pkt []byte, iphLen, tcphLen uint8, seq uint32, pshSet bool, gsoSize uint16, item tcpGROItem, bufs [][]byte, bufsOffset int) canCoalesce {
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pktTarget := bufs[item.bufsIndex][bufsOffset:]
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if tcphLen != item.tcphLen {
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// cannot coalesce with unequal tcp options len
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return coalesceUnavailable
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}
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if tcphLen > 20 {
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if !bytes.Equal(pkt[iphLen+20:iphLen+tcphLen], pktTarget[item.iphLen+20:iphLen+tcphLen]) {
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// cannot coalesce with unequal tcp options
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return coalesceUnavailable
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}
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}
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if !ipHeadersCanCoalesce(pkt, pktTarget) {
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return coalesceUnavailable
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}
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// seq adjacency
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lhsLen := item.gsoSize
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lhsLen += item.numMerged * item.gsoSize
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if seq == item.sentSeq+uint32(lhsLen) { // pkt aligns following item from a seq num perspective
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if item.pshSet {
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// We cannot append to a segment that has the PSH flag set, PSH
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// can only be set on the final segment in a reassembled group.
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return coalesceUnavailable
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}
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if len(pktTarget[iphLen+tcphLen:])%int(item.gsoSize) != 0 {
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// A smaller than gsoSize packet has been appended previously.
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// Nothing can come after a smaller packet on the end.
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return coalesceUnavailable
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}
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if gsoSize > item.gsoSize {
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// We cannot have a larger packet following a smaller one.
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return coalesceUnavailable
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}
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return coalesceAppend
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} else if seq+uint32(gsoSize) == item.sentSeq { // pkt aligns in front of item from a seq num perspective
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if pshSet {
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// We cannot prepend with a segment that has the PSH flag set, PSH
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// can only be set on the final segment in a reassembled group.
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return coalesceUnavailable
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}
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if gsoSize < item.gsoSize {
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// We cannot have a larger packet following a smaller one.
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return coalesceUnavailable
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}
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if gsoSize > item.gsoSize && item.numMerged > 0 {
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// There's at least one previous merge, and we're larger than all
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// previous. This would put multiple smaller packets on the end.
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return coalesceUnavailable
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}
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return coalescePrepend
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}
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return coalesceUnavailable
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}
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func checksumValid(pkt []byte, iphLen, proto uint8, isV6 bool) bool {
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srcAddrAt := ipv4SrcAddrOffset
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addrSize := 4
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if isV6 {
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srcAddrAt = ipv6SrcAddrOffset
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addrSize = 16
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}
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lenForPseudo := uint16(len(pkt) - int(iphLen))
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cSum := pseudoHeaderChecksumNoFold(proto, pkt[srcAddrAt:srcAddrAt+addrSize], pkt[srcAddrAt+addrSize:srcAddrAt+addrSize*2], lenForPseudo)
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return ^checksum(pkt[iphLen:], cSum) == 0
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}
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// coalesceResult represents the result of attempting to coalesce two TCP
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// packets.
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type coalesceResult int
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const (
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coalesceInsufficientCap coalesceResult = iota
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coalescePSHEnding
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coalesceItemInvalidCSum
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coalescePktInvalidCSum
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coalesceSuccess
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)
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// coalesceUDPPackets attempts to coalesce pkt with the packet described by
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// item, and returns the outcome.
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func coalesceUDPPackets(pkt []byte, item *udpGROItem, bufs [][]byte, bufsOffset int, isV6 bool) coalesceResult {
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pktHead := bufs[item.bufsIndex][bufsOffset:] // the packet that will end up at the front
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headersLen := item.iphLen + udphLen
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coalescedLen := len(bufs[item.bufsIndex][bufsOffset:]) + len(pkt) - int(headersLen)
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if cap(pktHead)-bufsOffset < coalescedLen {
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// We don't want to allocate a new underlying array if capacity is
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// too small.
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return coalesceInsufficientCap
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}
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if item.numMerged == 0 {
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if item.cSumKnownInvalid || !checksumValid(bufs[item.bufsIndex][bufsOffset:], item.iphLen, unix.IPPROTO_UDP, isV6) {
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return coalesceItemInvalidCSum
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}
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}
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if !checksumValid(pkt, item.iphLen, unix.IPPROTO_UDP, isV6) {
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return coalescePktInvalidCSum
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}
|
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extendBy := len(pkt) - int(headersLen)
|
|
bufs[item.bufsIndex] = append(bufs[item.bufsIndex], make([]byte, extendBy)...)
|
|
copy(bufs[item.bufsIndex][bufsOffset+len(pktHead):], pkt[headersLen:])
|
|
|
|
item.numMerged++
|
|
return coalesceSuccess
|
|
}
|
|
|
|
// coalesceTCPPackets attempts to coalesce pkt with the packet described by
|
|
// item, and returns the outcome. This function may swap bufs elements in the
|
|
// event of a prepend as item's bufs index is already being tracked for writing
|
|
// to a Device.
|
|
func coalesceTCPPackets(mode canCoalesce, pkt []byte, pktBuffsIndex int, gsoSize uint16, seq uint32, pshSet bool, item *tcpGROItem, bufs [][]byte, bufsOffset int, isV6 bool) coalesceResult {
|
|
var pktHead []byte // the packet that will end up at the front
|
|
headersLen := item.iphLen + item.tcphLen
|
|
coalescedLen := len(bufs[item.bufsIndex][bufsOffset:]) + len(pkt) - int(headersLen)
|
|
|
|
// Copy data
|
|
if mode == coalescePrepend {
|
|
pktHead = pkt
|
|
if cap(pkt)-bufsOffset < coalescedLen {
|
|
// We don't want to allocate a new underlying array if capacity is
|
|
// too small.
|
|
return coalesceInsufficientCap
|
|
}
|
|
if pshSet {
|
|
return coalescePSHEnding
|
|
}
|
|
if item.numMerged == 0 {
|
|
if !checksumValid(bufs[item.bufsIndex][bufsOffset:], item.iphLen, unix.IPPROTO_TCP, isV6) {
|
|
return coalesceItemInvalidCSum
|
|
}
|
|
}
|
|
if !checksumValid(pkt, item.iphLen, unix.IPPROTO_TCP, isV6) {
|
|
return coalescePktInvalidCSum
|
|
}
|
|
item.sentSeq = seq
|
|
extendBy := coalescedLen - len(pktHead)
|
|
bufs[pktBuffsIndex] = append(bufs[pktBuffsIndex], make([]byte, extendBy)...)
|
|
copy(bufs[pktBuffsIndex][bufsOffset+len(pkt):], bufs[item.bufsIndex][bufsOffset+int(headersLen):])
|
|
// Flip the slice headers in bufs as part of prepend. The index of item
|
|
// is already being tracked for writing.
|
|
bufs[item.bufsIndex], bufs[pktBuffsIndex] = bufs[pktBuffsIndex], bufs[item.bufsIndex]
|
|
} else {
|
|
pktHead = bufs[item.bufsIndex][bufsOffset:]
|
|
if cap(pktHead)-bufsOffset < coalescedLen {
|
|
// We don't want to allocate a new underlying array if capacity is
|
|
// too small.
|
|
return coalesceInsufficientCap
|
|
}
|
|
if item.numMerged == 0 {
|
|
if !checksumValid(bufs[item.bufsIndex][bufsOffset:], item.iphLen, unix.IPPROTO_TCP, isV6) {
|
|
return coalesceItemInvalidCSum
|
|
}
|
|
}
|
|
if !checksumValid(pkt, item.iphLen, unix.IPPROTO_TCP, isV6) {
|
|
return coalescePktInvalidCSum
|
|
}
|
|
if pshSet {
|
|
// We are appending a segment with PSH set.
|
|
item.pshSet = pshSet
|
|
pktHead[item.iphLen+tcpFlagsOffset] |= tcpFlagPSH
|
|
}
|
|
extendBy := len(pkt) - int(headersLen)
|
|
bufs[item.bufsIndex] = append(bufs[item.bufsIndex], make([]byte, extendBy)...)
|
|
copy(bufs[item.bufsIndex][bufsOffset+len(pktHead):], pkt[headersLen:])
|
|
}
|
|
|
|
if gsoSize > item.gsoSize {
|
|
item.gsoSize = gsoSize
|
|
}
|
|
|
|
item.numMerged++
|
|
return coalesceSuccess
|
|
}
|
|
|
|
const (
|
|
ipv4FlagMoreFragments uint8 = 0x20
|
|
)
|
|
|
|
const (
|
|
ipv4SrcAddrOffset = 12
|
|
ipv6SrcAddrOffset = 8
|
|
maxUint16 = 1<<16 - 1
|
|
)
|
|
|
|
type groResult int
|
|
|
|
const (
|
|
groResultNoop groResult = iota
|
|
groResultTableInsert
|
|
groResultCoalesced
|
|
)
|
|
|
|
// tcpGRO evaluates the TCP packet at pktI in bufs for coalescing with
|
|
// existing packets tracked in table. It returns a groResultNoop when no
|
|
// action was taken, groResultTableInsert when the evaluated packet was
|
|
// inserted into table, and groResultCoalesced when the evaluated packet was
|
|
// coalesced with another packet in table.
|
|
func tcpGRO(bufs [][]byte, offset int, pktI int, table *tcpGROTable, isV6 bool) groResult {
|
|
pkt := bufs[pktI][offset:]
|
|
if len(pkt) > maxUint16 {
|
|
// A valid IPv4 or IPv6 packet will never exceed this.
|
|
return groResultNoop
|
|
}
|
|
iphLen := int((pkt[0] & 0x0F) * 4)
|
|
if isV6 {
|
|
iphLen = 40
|
|
ipv6HPayloadLen := int(binary.BigEndian.Uint16(pkt[4:]))
|
|
if ipv6HPayloadLen != len(pkt)-iphLen {
|
|
return groResultNoop
|
|
}
|
|
} else {
|
|
totalLen := int(binary.BigEndian.Uint16(pkt[2:]))
|
|
if totalLen != len(pkt) {
|
|
return groResultNoop
|
|
}
|
|
}
|
|
if len(pkt) < iphLen {
|
|
return groResultNoop
|
|
}
|
|
tcphLen := int((pkt[iphLen+12] >> 4) * 4)
|
|
if tcphLen < 20 || tcphLen > 60 {
|
|
return groResultNoop
|
|
}
|
|
if len(pkt) < iphLen+tcphLen {
|
|
return groResultNoop
|
|
}
|
|
if !isV6 {
|
|
if pkt[6]&ipv4FlagMoreFragments != 0 || pkt[6]<<3 != 0 || pkt[7] != 0 {
|
|
// no GRO support for fragmented segments for now
|
|
return groResultNoop
|
|
}
|
|
}
|
|
tcpFlags := pkt[iphLen+tcpFlagsOffset]
|
|
var pshSet bool
|
|
// not a candidate if any non-ACK flags (except PSH+ACK) are set
|
|
if tcpFlags != tcpFlagACK {
|
|
if pkt[iphLen+tcpFlagsOffset] != tcpFlagACK|tcpFlagPSH {
|
|
return groResultNoop
|
|
}
|
|
pshSet = true
|
|
}
|
|
gsoSize := uint16(len(pkt) - tcphLen - iphLen)
|
|
// not a candidate if payload len is 0
|
|
if gsoSize < 1 {
|
|
return groResultNoop
|
|
}
|
|
seq := binary.BigEndian.Uint32(pkt[iphLen+4:])
|
|
srcAddrOffset := ipv4SrcAddrOffset
|
|
addrLen := 4
|
|
if isV6 {
|
|
srcAddrOffset = ipv6SrcAddrOffset
|
|
addrLen = 16
|
|
}
|
|
items, existing := table.lookupOrInsert(pkt, srcAddrOffset, srcAddrOffset+addrLen, iphLen, tcphLen, pktI)
|
|
if !existing {
|
|
return groResultTableInsert
|
|
}
|
|
for i := len(items) - 1; i >= 0; i-- {
|
|
// In the best case of packets arriving in order iterating in reverse is
|
|
// more efficient if there are multiple items for a given flow. This
|
|
// also enables a natural table.deleteAt() in the
|
|
// coalesceItemInvalidCSum case without the need for index tracking.
|
|
// This algorithm makes a best effort to coalesce in the event of
|
|
// unordered packets, where pkt may land anywhere in items from a
|
|
// sequence number perspective, however once an item is inserted into
|
|
// the table it is never compared across other items later.
|
|
item := items[i]
|
|
can := tcpPacketsCanCoalesce(pkt, uint8(iphLen), uint8(tcphLen), seq, pshSet, gsoSize, item, bufs, offset)
|
|
if can != coalesceUnavailable {
|
|
result := coalesceTCPPackets(can, pkt, pktI, gsoSize, seq, pshSet, &item, bufs, offset, isV6)
|
|
switch result {
|
|
case coalesceSuccess:
|
|
table.updateAt(item, i)
|
|
return groResultCoalesced
|
|
case coalesceItemInvalidCSum:
|
|
// delete the item with an invalid csum
|
|
table.deleteAt(item.key, i)
|
|
case coalescePktInvalidCSum:
|
|
// no point in inserting an item that we can't coalesce
|
|
return groResultNoop
|
|
default:
|
|
}
|
|
}
|
|
}
|
|
// failed to coalesce with any other packets; store the item in the flow
|
|
table.insert(pkt, srcAddrOffset, srcAddrOffset+addrLen, iphLen, tcphLen, pktI)
|
|
return groResultTableInsert
|
|
}
|
|
|
|
// applyTCPCoalesceAccounting updates bufs to account for coalescing based on the
|
|
// metadata found in table.
|
|
func applyTCPCoalesceAccounting(bufs [][]byte, offset int, table *tcpGROTable) error {
|
|
for _, items := range table.itemsByFlow {
|
|
for _, item := range items {
|
|
if item.numMerged > 0 {
|
|
hdr := virtioNetHdr{
|
|
flags: unix.VIRTIO_NET_HDR_F_NEEDS_CSUM, // this turns into CHECKSUM_PARTIAL in the skb
|
|
hdrLen: uint16(item.iphLen + item.tcphLen),
|
|
gsoSize: item.gsoSize,
|
|
csumStart: uint16(item.iphLen),
|
|
csumOffset: 16,
|
|
}
|
|
pkt := bufs[item.bufsIndex][offset:]
|
|
|
|
// Recalculate the total len (IPv4) or payload len (IPv6).
|
|
// Recalculate the (IPv4) header checksum.
|
|
if item.key.isV6 {
|
|
hdr.gsoType = unix.VIRTIO_NET_HDR_GSO_TCPV6
|
|
binary.BigEndian.PutUint16(pkt[4:], uint16(len(pkt))-uint16(item.iphLen)) // set new IPv6 header payload len
|
|
} else {
|
|
hdr.gsoType = unix.VIRTIO_NET_HDR_GSO_TCPV4
|
|
pkt[10], pkt[11] = 0, 0
|
|
binary.BigEndian.PutUint16(pkt[2:], uint16(len(pkt))) // set new total length
|
|
iphCSum := ^checksum(pkt[:item.iphLen], 0) // compute IPv4 header checksum
|
|
binary.BigEndian.PutUint16(pkt[10:], iphCSum) // set IPv4 header checksum field
|
|
}
|
|
err := hdr.encode(bufs[item.bufsIndex][offset-virtioNetHdrLen:])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Calculate the pseudo header checksum and place it at the TCP
|
|
// checksum offset. Downstream checksum offloading will combine
|
|
// this with computation of the tcp header and payload checksum.
|
|
addrLen := 4
|
|
addrOffset := ipv4SrcAddrOffset
|
|
if item.key.isV6 {
|
|
addrLen = 16
|
|
addrOffset = ipv6SrcAddrOffset
|
|
}
|
|
srcAddrAt := offset + addrOffset
|
|
srcAddr := bufs[item.bufsIndex][srcAddrAt : srcAddrAt+addrLen]
|
|
dstAddr := bufs[item.bufsIndex][srcAddrAt+addrLen : srcAddrAt+addrLen*2]
|
|
psum := pseudoHeaderChecksumNoFold(unix.IPPROTO_TCP, srcAddr, dstAddr, uint16(len(pkt)-int(item.iphLen)))
|
|
binary.BigEndian.PutUint16(pkt[hdr.csumStart+hdr.csumOffset:], checksum([]byte{}, psum))
|
|
} else {
|
|
hdr := virtioNetHdr{}
|
|
err := hdr.encode(bufs[item.bufsIndex][offset-virtioNetHdrLen:])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// applyUDPCoalesceAccounting updates bufs to account for coalescing based on the
|
|
// metadata found in table.
|
|
func applyUDPCoalesceAccounting(bufs [][]byte, offset int, table *udpGROTable) error {
|
|
for _, items := range table.itemsByFlow {
|
|
for _, item := range items {
|
|
if item.numMerged > 0 {
|
|
hdr := virtioNetHdr{
|
|
flags: unix.VIRTIO_NET_HDR_F_NEEDS_CSUM, // this turns into CHECKSUM_PARTIAL in the skb
|
|
hdrLen: uint16(item.iphLen + udphLen),
|
|
gsoSize: item.gsoSize,
|
|
csumStart: uint16(item.iphLen),
|
|
csumOffset: 6,
|
|
}
|
|
pkt := bufs[item.bufsIndex][offset:]
|
|
|
|
// Recalculate the total len (IPv4) or payload len (IPv6).
|
|
// Recalculate the (IPv4) header checksum.
|
|
hdr.gsoType = unix.VIRTIO_NET_HDR_GSO_UDP_L4
|
|
if item.key.isV6 {
|
|
binary.BigEndian.PutUint16(pkt[4:], uint16(len(pkt))-uint16(item.iphLen)) // set new IPv6 header payload len
|
|
} else {
|
|
pkt[10], pkt[11] = 0, 0
|
|
binary.BigEndian.PutUint16(pkt[2:], uint16(len(pkt))) // set new total length
|
|
iphCSum := ^checksum(pkt[:item.iphLen], 0) // compute IPv4 header checksum
|
|
binary.BigEndian.PutUint16(pkt[10:], iphCSum) // set IPv4 header checksum field
|
|
}
|
|
err := hdr.encode(bufs[item.bufsIndex][offset-virtioNetHdrLen:])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Recalculate the UDP len field value
|
|
binary.BigEndian.PutUint16(pkt[item.iphLen+4:], uint16(len(pkt[item.iphLen:])))
|
|
|
|
// Calculate the pseudo header checksum and place it at the UDP
|
|
// checksum offset. Downstream checksum offloading will combine
|
|
// this with computation of the udp header and payload checksum.
|
|
addrLen := 4
|
|
addrOffset := ipv4SrcAddrOffset
|
|
if item.key.isV6 {
|
|
addrLen = 16
|
|
addrOffset = ipv6SrcAddrOffset
|
|
}
|
|
srcAddrAt := offset + addrOffset
|
|
srcAddr := bufs[item.bufsIndex][srcAddrAt : srcAddrAt+addrLen]
|
|
dstAddr := bufs[item.bufsIndex][srcAddrAt+addrLen : srcAddrAt+addrLen*2]
|
|
psum := pseudoHeaderChecksumNoFold(unix.IPPROTO_UDP, srcAddr, dstAddr, uint16(len(pkt)-int(item.iphLen)))
|
|
binary.BigEndian.PutUint16(pkt[hdr.csumStart+hdr.csumOffset:], checksum([]byte{}, psum))
|
|
} else {
|
|
hdr := virtioNetHdr{}
|
|
err := hdr.encode(bufs[item.bufsIndex][offset-virtioNetHdrLen:])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
type groCandidateType uint8
|
|
|
|
const (
|
|
notGROCandidate groCandidateType = iota
|
|
tcp4GROCandidate
|
|
tcp6GROCandidate
|
|
udp4GROCandidate
|
|
udp6GROCandidate
|
|
)
|
|
|
|
func packetIsGROCandidate(b []byte, canUDPGRO bool) groCandidateType {
|
|
if len(b) < 28 {
|
|
return notGROCandidate
|
|
}
|
|
if b[0]>>4 == 4 {
|
|
if b[0]&0x0F != 5 {
|
|
// IPv4 packets w/IP options do not coalesce
|
|
return notGROCandidate
|
|
}
|
|
if b[9] == unix.IPPROTO_TCP && len(b) >= 40 {
|
|
return tcp4GROCandidate
|
|
}
|
|
if b[9] == unix.IPPROTO_UDP && canUDPGRO {
|
|
return udp4GROCandidate
|
|
}
|
|
} else if b[0]>>4 == 6 {
|
|
if b[6] == unix.IPPROTO_TCP && len(b) >= 60 {
|
|
return tcp6GROCandidate
|
|
}
|
|
if b[6] == unix.IPPROTO_UDP && len(b) >= 48 && canUDPGRO {
|
|
return udp6GROCandidate
|
|
}
|
|
}
|
|
return notGROCandidate
|
|
}
|
|
|
|
const (
|
|
udphLen = 8
|
|
)
|
|
|
|
// udpGRO evaluates the UDP packet at pktI in bufs for coalescing with
|
|
// existing packets tracked in table. It returns a groResultNoop when no
|
|
// action was taken, groResultTableInsert when the evaluated packet was
|
|
// inserted into table, and groResultCoalesced when the evaluated packet was
|
|
// coalesced with another packet in table.
|
|
func udpGRO(bufs [][]byte, offset int, pktI int, table *udpGROTable, isV6 bool) groResult {
|
|
pkt := bufs[pktI][offset:]
|
|
if len(pkt) > maxUint16 {
|
|
// A valid IPv4 or IPv6 packet will never exceed this.
|
|
return groResultNoop
|
|
}
|
|
iphLen := int((pkt[0] & 0x0F) * 4)
|
|
if isV6 {
|
|
iphLen = 40
|
|
ipv6HPayloadLen := int(binary.BigEndian.Uint16(pkt[4:]))
|
|
if ipv6HPayloadLen != len(pkt)-iphLen {
|
|
return groResultNoop
|
|
}
|
|
} else {
|
|
totalLen := int(binary.BigEndian.Uint16(pkt[2:]))
|
|
if totalLen != len(pkt) {
|
|
return groResultNoop
|
|
}
|
|
}
|
|
if len(pkt) < iphLen {
|
|
return groResultNoop
|
|
}
|
|
if len(pkt) < iphLen+udphLen {
|
|
return groResultNoop
|
|
}
|
|
if !isV6 {
|
|
if pkt[6]&ipv4FlagMoreFragments != 0 || pkt[6]<<3 != 0 || pkt[7] != 0 {
|
|
// no GRO support for fragmented segments for now
|
|
return groResultNoop
|
|
}
|
|
}
|
|
gsoSize := uint16(len(pkt) - udphLen - iphLen)
|
|
// not a candidate if payload len is 0
|
|
if gsoSize < 1 {
|
|
return groResultNoop
|
|
}
|
|
srcAddrOffset := ipv4SrcAddrOffset
|
|
addrLen := 4
|
|
if isV6 {
|
|
srcAddrOffset = ipv6SrcAddrOffset
|
|
addrLen = 16
|
|
}
|
|
items, existing := table.lookupOrInsert(pkt, srcAddrOffset, srcAddrOffset+addrLen, iphLen, pktI)
|
|
if !existing {
|
|
return groResultTableInsert
|
|
}
|
|
// With UDP we only check the last item, otherwise we could reorder packets
|
|
// for a given flow. We must also always insert a new item, or successfully
|
|
// coalesce with an existing item, for the same reason.
|
|
item := items[len(items)-1]
|
|
can := udpPacketsCanCoalesce(pkt, uint8(iphLen), gsoSize, item, bufs, offset)
|
|
var pktCSumKnownInvalid bool
|
|
if can == coalesceAppend {
|
|
result := coalesceUDPPackets(pkt, &item, bufs, offset, isV6)
|
|
switch result {
|
|
case coalesceSuccess:
|
|
table.updateAt(item, len(items)-1)
|
|
return groResultCoalesced
|
|
case coalesceItemInvalidCSum:
|
|
// If the existing item has an invalid csum we take no action. A new
|
|
// item will be stored after it, and the existing item will never be
|
|
// revisited as part of future coalescing candidacy checks.
|
|
case coalescePktInvalidCSum:
|
|
// We must insert a new item, but we also mark it as invalid csum
|
|
// to prevent a repeat checksum validation.
|
|
pktCSumKnownInvalid = true
|
|
default:
|
|
}
|
|
}
|
|
// failed to coalesce with any other packets; store the item in the flow
|
|
table.insert(pkt, srcAddrOffset, srcAddrOffset+addrLen, iphLen, pktI, pktCSumKnownInvalid)
|
|
return groResultTableInsert
|
|
}
|
|
|
|
// handleGRO evaluates bufs for GRO, and writes the indices of the resulting
|
|
// packets into toWrite. toWrite, tcpTable, and udpTable should initially be
|
|
// empty (but non-nil), and are passed in to save allocs as the caller may reset
|
|
// and recycle them across vectors of packets. canUDPGRO indicates if UDP GRO is
|
|
// supported.
|
|
func handleGRO(bufs [][]byte, offset int, tcpTable *tcpGROTable, udpTable *udpGROTable, canUDPGRO bool, toWrite *[]int) error {
|
|
for i := range bufs {
|
|
if offset < virtioNetHdrLen || offset > len(bufs[i])-1 {
|
|
return errors.New("invalid offset")
|
|
}
|
|
var result groResult
|
|
switch packetIsGROCandidate(bufs[i][offset:], canUDPGRO) {
|
|
case tcp4GROCandidate:
|
|
result = tcpGRO(bufs, offset, i, tcpTable, false)
|
|
case tcp6GROCandidate:
|
|
result = tcpGRO(bufs, offset, i, tcpTable, true)
|
|
case udp4GROCandidate:
|
|
result = udpGRO(bufs, offset, i, udpTable, false)
|
|
case udp6GROCandidate:
|
|
result = udpGRO(bufs, offset, i, udpTable, true)
|
|
}
|
|
switch result {
|
|
case groResultNoop:
|
|
hdr := virtioNetHdr{}
|
|
err := hdr.encode(bufs[i][offset-virtioNetHdrLen:])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
fallthrough
|
|
case groResultTableInsert:
|
|
*toWrite = append(*toWrite, i)
|
|
}
|
|
}
|
|
errTCP := applyTCPCoalesceAccounting(bufs, offset, tcpTable)
|
|
errUDP := applyUDPCoalesceAccounting(bufs, offset, udpTable)
|
|
return errors.Join(errTCP, errUDP)
|
|
}
|
|
|
|
// gsoSplit splits packets from in into outBuffs, writing the size of each
|
|
// element into sizes. It returns the number of buffers populated, and/or an
|
|
// error.
|
|
func gsoSplit(in []byte, hdr virtioNetHdr, outBuffs [][]byte, sizes []int, outOffset int, isV6 bool) (int, error) {
|
|
iphLen := int(hdr.csumStart)
|
|
srcAddrOffset := ipv6SrcAddrOffset
|
|
addrLen := 16
|
|
if !isV6 {
|
|
in[10], in[11] = 0, 0 // clear ipv4 header checksum
|
|
srcAddrOffset = ipv4SrcAddrOffset
|
|
addrLen = 4
|
|
}
|
|
transportCsumAt := int(hdr.csumStart + hdr.csumOffset)
|
|
in[transportCsumAt], in[transportCsumAt+1] = 0, 0 // clear tcp/udp checksum
|
|
var firstTCPSeqNum uint32
|
|
var protocol uint8
|
|
if hdr.gsoType == unix.VIRTIO_NET_HDR_GSO_TCPV4 || hdr.gsoType == unix.VIRTIO_NET_HDR_GSO_TCPV6 {
|
|
protocol = unix.IPPROTO_TCP
|
|
firstTCPSeqNum = binary.BigEndian.Uint32(in[hdr.csumStart+4:])
|
|
} else {
|
|
protocol = unix.IPPROTO_UDP
|
|
}
|
|
nextSegmentDataAt := int(hdr.hdrLen)
|
|
i := 0
|
|
for ; nextSegmentDataAt < len(in); i++ {
|
|
if i == len(outBuffs) {
|
|
return i - 1, ErrTooManySegments
|
|
}
|
|
nextSegmentEnd := nextSegmentDataAt + int(hdr.gsoSize)
|
|
if nextSegmentEnd > len(in) {
|
|
nextSegmentEnd = len(in)
|
|
}
|
|
segmentDataLen := nextSegmentEnd - nextSegmentDataAt
|
|
totalLen := int(hdr.hdrLen) + segmentDataLen
|
|
sizes[i] = totalLen
|
|
out := outBuffs[i][outOffset:]
|
|
|
|
copy(out, in[:iphLen])
|
|
if !isV6 {
|
|
// For IPv4 we are responsible for incrementing the ID field,
|
|
// updating the total len field, and recalculating the header
|
|
// checksum.
|
|
if i > 0 {
|
|
id := binary.BigEndian.Uint16(out[4:])
|
|
id += uint16(i)
|
|
binary.BigEndian.PutUint16(out[4:], id)
|
|
}
|
|
binary.BigEndian.PutUint16(out[2:], uint16(totalLen))
|
|
ipv4CSum := ^checksum(out[:iphLen], 0)
|
|
binary.BigEndian.PutUint16(out[10:], ipv4CSum)
|
|
} else {
|
|
// For IPv6 we are responsible for updating the payload length field.
|
|
binary.BigEndian.PutUint16(out[4:], uint16(totalLen-iphLen))
|
|
}
|
|
|
|
// copy transport header
|
|
copy(out[hdr.csumStart:hdr.hdrLen], in[hdr.csumStart:hdr.hdrLen])
|
|
|
|
if protocol == unix.IPPROTO_TCP {
|
|
// set TCP seq and adjust TCP flags
|
|
tcpSeq := firstTCPSeqNum + uint32(hdr.gsoSize*uint16(i))
|
|
binary.BigEndian.PutUint32(out[hdr.csumStart+4:], tcpSeq)
|
|
if nextSegmentEnd != len(in) {
|
|
// FIN and PSH should only be set on last segment
|
|
clearFlags := tcpFlagFIN | tcpFlagPSH
|
|
out[hdr.csumStart+tcpFlagsOffset] &^= clearFlags
|
|
}
|
|
} else {
|
|
// set UDP header len
|
|
binary.BigEndian.PutUint16(out[hdr.csumStart+4:], uint16(segmentDataLen)+(hdr.hdrLen-hdr.csumStart))
|
|
}
|
|
|
|
// payload
|
|
copy(out[hdr.hdrLen:], in[nextSegmentDataAt:nextSegmentEnd])
|
|
|
|
// transport checksum
|
|
transportHeaderLen := int(hdr.hdrLen - hdr.csumStart)
|
|
lenForPseudo := uint16(transportHeaderLen + segmentDataLen)
|
|
transportCSumNoFold := pseudoHeaderChecksumNoFold(protocol, in[srcAddrOffset:srcAddrOffset+addrLen], in[srcAddrOffset+addrLen:srcAddrOffset+addrLen*2], lenForPseudo)
|
|
transportCSum := ^checksum(out[hdr.csumStart:totalLen], transportCSumNoFold)
|
|
binary.BigEndian.PutUint16(out[hdr.csumStart+hdr.csumOffset:], transportCSum)
|
|
|
|
nextSegmentDataAt += int(hdr.gsoSize)
|
|
}
|
|
return i, nil
|
|
}
|
|
|
|
func gsoNoneChecksum(in []byte, cSumStart, cSumOffset uint16) error {
|
|
cSumAt := cSumStart + cSumOffset
|
|
// The initial value at the checksum offset should be summed with the
|
|
// checksum we compute. This is typically the pseudo-header checksum.
|
|
initial := binary.BigEndian.Uint16(in[cSumAt:])
|
|
in[cSumAt], in[cSumAt+1] = 0, 0
|
|
binary.BigEndian.PutUint16(in[cSumAt:], ^checksum(in[cSumStart:], uint64(initial)))
|
|
return nil
|
|
}
|