mirror of
https://github.com/tailscale/tailscale.git
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55 lines
2.1 KiB
Go
55 lines
2.1 KiB
Go
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package netkernelconf
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import (
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"fmt"
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"github.com/safchain/ethtool"
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)
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// CheckUDPGROForwarding checks if the machine is optimally configured to
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// forward UDP packets between the default route and Tailscale TUN interfaces.
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// It returns a non-nil warn in the case that the configuration is suboptimal.
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// It returns a non-nil err in the case that an error is encountered while
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// performing the check.
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func CheckUDPGROForwarding(tunInterface, defaultRouteInterface string) (warn, err error) {
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const txFeature = "tx-udp-segmentation"
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const rxWantFeature = "rx-udp-gro-forwarding"
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const rxDoNotWantFeature = "rx-gro-list"
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const kbLink = "\nSee https://tailscale.com/s/ethtool-config-udp-gro"
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errWithPrefix := func(format string, a ...any) error {
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const errPrefix = "couldn't check system's UDP GRO forwarding configuration, "
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return fmt.Errorf(errPrefix+format, a...)
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}
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e, err := ethtool.NewEthtool()
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if err != nil {
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return nil, errWithPrefix("failed to init ethtool: %v", err)
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}
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defer e.Close()
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tunFeatures, err := e.Features(tunInterface)
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if err != nil {
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return nil, errWithPrefix("failed to retrieve TUN device features: %v", err)
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}
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if !tunFeatures[txFeature] {
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// if txFeature is disabled/nonexistent on the TUN then UDP GRO
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// forwarding doesn't matter, we won't be taking advantage of it.
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return nil, nil
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}
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defaultFeatures, err := e.Features(defaultRouteInterface)
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if err != nil {
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return nil, errWithPrefix("failed to retrieve default route interface features: %v", err)
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}
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defaultHasRxWant, ok := defaultFeatures[rxWantFeature]
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if !ok {
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// unlikely the feature is nonexistant with txFeature in the TUN driver
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// being added to the kernel later than rxWantFeature, but let's be sure
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return nil, nil
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}
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if !defaultHasRxWant || defaultFeatures[rxDoNotWantFeature] {
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return fmt.Errorf("UDP GRO forwarding is suboptimally configured on %s, UDP forwarding throughput capability will increase with a configuration change.%s", defaultRouteInterface, kbLink), nil
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}
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return nil, nil
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}
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