tailscale/wgengine/router/callback.go
Val 1138f4eb5f wgengine/router,ipn/ipnlocal: add MTU field to router config
The MacOS client can't set the MTU when creating the tun due to lack
of permissions, so add it to the router config and have MacOS set it
in the callback using a method that it does have permissions for.

Updates #8219

Signed-off-by: Val <valerie@tailscale.com>
2023-07-19 04:22:12 -07:00

85 lines
2.3 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package router
import (
"sync"
"tailscale.com/net/dns"
)
// CallbackRouter is an implementation of both Router and dns.OSConfigurator.
// When either network or DNS settings are changed, SetBoth is called with both configs.
// Mainly used as a shim for OSes that want to set both network and
// DNS configuration simultaneously (Mac, iOS, Android).
type CallbackRouter struct {
SetBoth func(rcfg *Config, dcfg *dns.OSConfig) error
SplitDNS bool
// GetBaseConfigFunc optionally specifies a function to return the current DNS
// config in response to GetBaseConfig.
//
// If nil, reading the current config isn't supported and GetBaseConfig()
// will return ErrGetBaseConfigNotSupported.
GetBaseConfigFunc func() (dns.OSConfig, error)
// InitialMTU is the MTU the tun should be initialized with.
// Zero means don't change the MTU from the default. This MTU
// is applied only once, shortly after the TUN is created, and
// ignored thereafter.
InitialMTU uint32
mu sync.Mutex // protects all the following
didSetMTU bool // if we set the MTU already
rcfg *Config // last applied router config
dcfg *dns.OSConfig // last applied DNS config
}
// Up implements Router.
func (r *CallbackRouter) Up() error {
return nil // TODO: check that all callers have no need for initialization
}
// Set implements Router.
func (r *CallbackRouter) Set(rcfg *Config) error {
r.mu.Lock()
defer r.mu.Unlock()
if r.rcfg.Equal(rcfg) {
return nil
}
if r.didSetMTU == false {
r.didSetMTU = true
rcfg.NewMTU = int(r.InitialMTU)
}
r.rcfg = rcfg
return r.SetBoth(r.rcfg, r.dcfg)
}
// SetDNS implements dns.OSConfigurator.
func (r *CallbackRouter) SetDNS(dcfg dns.OSConfig) error {
r.mu.Lock()
defer r.mu.Unlock()
if r.dcfg != nil && r.dcfg.Equal(dcfg) {
return nil
}
r.dcfg = &dcfg
return r.SetBoth(r.rcfg, r.dcfg)
}
// SupportsSplitDNS implements dns.OSConfigurator.
func (r *CallbackRouter) SupportsSplitDNS() bool {
return r.SplitDNS
}
func (r *CallbackRouter) GetBaseConfig() (dns.OSConfig, error) {
if r.GetBaseConfigFunc == nil {
return dns.OSConfig{}, dns.ErrGetBaseConfigNotSupported
}
return r.GetBaseConfigFunc()
}
func (r *CallbackRouter) Close() error {
return r.SetBoth(nil, nil) // TODO: check if makes sense
}