tailscale/wgengine/router/router.go

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// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package router presents an interface to manipulate the host network
// stack's state.
package router
import (
"golang.zx2c4.com/wireguard/tun"
"inet.af/netaddr"
"tailscale.com/types/logger"
"tailscale.com/types/preftype"
"tailscale.com/wgengine/monitor"
)
// Router is responsible for managing the system network stack.
//
// There is typically only one instance of this interface per process.
type Router interface {
// Up brings the router up.
Up() error
// Set updates the OS network stack with a new Config. It may be
// called multiple times with identical Configs, which the
// implementation should handle gracefully.
Set(*Config) error
// Close closes the router.
Close() error
}
// New returns a new Router for the current platform, using the
// provided tun device.
//
// If linkMon is nil, it's not used. It's currently (2021-07-20) only
// used on Linux in some situations.
func New(logf logger.Logf, tundev tun.Device, linkMon *monitor.Mon) (Router, error) {
logf = logger.WithPrefix(logf, "router: ")
return newUserspaceRouter(logf, tundev, linkMon)
}
// Cleanup restores the system network configuration to its original state
// in case the Tailscale daemon terminated without closing the router.
// No other state needs to be instantiated before this runs.
func Cleanup(logf logger.Logf, interfaceName string) {
cleanup(logf, interfaceName)
}
// Config is the subset of Tailscale configuration that is relevant to
// the OS's network stack.
type Config struct {
// LocalAddrs are the address(es) for this node. This is
// typically one IPv4/32 (the 100.x.y.z CGNAT) and one
// IPv6/128 (Tailscale ULA).
LocalAddrs []netaddr.IPPrefix
// Routes are the routes that point into the Tailscale
// interface. These are the /32 and /128 routes to peers, as
// well as any other subnets that peers are advertising and
// this node has chosen to use.
Routes []netaddr.IPPrefix
// LocalRoutes are the routes that should not be routed through Tailscale.
// There are no priorities set in how these routes are added, normal
// routing rules apply.
LocalRoutes []netaddr.IPPrefix
// Linux-only things below, ignored on other platforms.
SubnetRoutes []netaddr.IPPrefix // subnets being advertised to other Tailscale nodes
SNATSubnetRoutes bool // SNAT traffic to local subnets
NetfilterMode preftype.NetfilterMode // how much to manage netfilter rules
}
// shutdownConfig is a routing configuration that removes all router
// state from the OS. It's the config used when callers pass in a nil
// Config.
var shutdownConfig = Config{}