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net/{batching,packet},wgengine/magicsock: export batchingConn (#16848)

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For eventual use by net/udprelay.Server.

Updates tailscale/corp#31164

Signed-off-by: Jordan Whited <jordan@tailscale.com>
This commit is contained in:
Jordan Whited
2025-08-13 13:13:11 -07:00
committed by GitHub
parent f22c7657e5
commit 16bc0a5558
25 changed files with 328 additions and 268 deletions
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wgengine/magicsock/rebinding_conn.go
+21 -19
View File
@@ -13,6 +13,7 @@ import (
"syscall"
"golang.org/x/net/ipv6"
"tailscale.com/net/batching"
"tailscale.com/net/netaddr"
"tailscale.com/net/packet"
"tailscale.com/types/nettype"
@@ -42,7 +43,7 @@ type RebindingUDPConn struct {
// disrupting surrounding code that assumes nettype.PacketConn is a
// *net.UDPConn.
func (c *RebindingUDPConn) setConnLocked(p nettype.PacketConn, network string, batchSize int) {
upc := tryUpgradeToBatchingConn(p, network, batchSize)
upc := batching.TryUpgradeToConn(p, network, batchSize)
c.pconn = upc
c.pconnAtomic.Store(&upc)
c.port = uint16(c.localAddrLocked().Port)
@@ -72,25 +73,27 @@ func (c *RebindingUDPConn) ReadFromUDPAddrPort(b []byte) (int, netip.AddrPort, e
return c.readFromWithInitPconn(*c.pconnAtomic.Load(), b)
}
// WriteBatchTo writes buffs to addr.
func (c *RebindingUDPConn) WriteBatchTo(buffs [][]byte, addr epAddr, offset int) error {
// WriteWireGuardBatchTo writes buffs to addr. It serves primarily as an alias
// for [batching.Conn.WriteBatchTo], with fallback to single packet operations
// if c.pconn is not a [batching.Conn].
//
// WriteWireGuardBatchTo assumes buffs are WireGuard packets, which is notable
// for Geneve encapsulation: Geneve protocol is set to [packet.GeneveProtocolWireGuard],
// and the control bit is left unset.
func (c *RebindingUDPConn) WriteWireGuardBatchTo(buffs [][]byte, addr epAddr, offset int) error {
if offset != packet.GeneveFixedHeaderLength {
return fmt.Errorf("RebindingUDPConn.WriteBatchTo: [unexpected] offset (%d) != Geneve header length (%d)", offset, packet.GeneveFixedHeaderLength)
return fmt.Errorf("RebindingUDPConn.WriteWireGuardBatchTo: [unexpected] offset (%d) != Geneve header length (%d)", offset, packet.GeneveFixedHeaderLength)
}
gh := packet.GeneveHeader{
Protocol: packet.GeneveProtocolWireGuard,
VNI: addr.vni,
}
for {
pconn := *c.pconnAtomic.Load()
b, ok := pconn.(batchingConn)
b, ok := pconn.(batching.Conn)
if !ok {
vniIsSet := addr.vni.isSet()
var gh packet.GeneveHeader
if vniIsSet {
gh = packet.GeneveHeader{
Protocol: packet.GeneveProtocolWireGuard,
VNI: addr.vni.get(),
}
}
for _, buf := range buffs {
if vniIsSet {
if gh.VNI.IsSet() {
gh.Encode(buf)
} else {
buf = buf[offset:]
@@ -102,7 +105,7 @@ func (c *RebindingUDPConn) WriteBatchTo(buffs [][]byte, addr epAddr, offset int)
}
return nil
}
err := b.WriteBatchTo(buffs, addr, offset)
err := b.WriteBatchTo(buffs, addr.ap, gh, offset)
if err != nil {
if pconn != c.currentConn() {
continue
@@ -113,13 +116,12 @@ func (c *RebindingUDPConn) WriteBatchTo(buffs [][]byte, addr epAddr, offset int)
}
}
// ReadBatch reads messages from c into msgs. It returns the number of messages
// the caller should evaluate for nonzero len, as a zero len message may fall
// on either side of a nonzero.
// ReadBatch is an alias for [batching.Conn.ReadBatch] with fallback to single
// packet operations if c.pconn is not a [batching.Conn].
func (c *RebindingUDPConn) ReadBatch(msgs []ipv6.Message, flags int) (int, error) {
for {
pconn := *c.pconnAtomic.Load()
b, ok := pconn.(batchingConn)
b, ok := pconn.(batching.Conn)
if !ok {
n, ap, err := c.readFromWithInitPconn(pconn, msgs[0].Buffers[0])
if err == nil {