wgengine/magicsock: avoid ReadBatch/WriteBatch on old Linux kernels

Fixes #6807

Change-Id: I161424ef8a7338e1941d5e43d72dc6529993a0e3
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
pull/6810/head
Brad Fitzpatrick 2 years ago committed by Brad Fitzpatrick
parent 0372e14d79
commit 2eff9c8277

@ -37,6 +37,7 @@ import (
"tailscale.com/derp/derphttp"
"tailscale.com/disco"
"tailscale.com/health"
"tailscale.com/hostinfo"
"tailscale.com/ipn/ipnstate"
"tailscale.com/logtail/backoff"
"tailscale.com/net/connstats"
@ -3208,6 +3209,14 @@ type RebindingUDPConn struct {
func upgradePacketConn(p nettype.PacketConn, network string) nettype.PacketConn {
uc, ok := p.(*net.UDPConn)
if ok && runtime.GOOS == "linux" && (network == "udp4" || network == "udp6") {
// recvmmsg/sendmmsg were added in 2.6.33 but we support down to 2.6.32
// for old NAS devices. See https://github.com/tailscale/tailscale/issues/6807.
// As a cheap heuristic: if the Linux kernel starts with "2", just consider
// it too old for the fast paths. Nobody who cares about performance runs such
// ancient kernels.
if strings.HasPrefix(hostinfo.GetOSVersion(), "2") {
return p
}
// Non-Linux does not support batch operations. x/net will fall back to
// recv/sendmsg, but not all platforms have recv/sendmsg support. Keep
// this simple for now.

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