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tailscale/net/tsaddr/tsaddr.go

123 lines
3.4 KiB
Go

// 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 tsaddr handles Tailscale-specific IPs and ranges.
package tsaddr
import (
"sync"
"inet.af/netaddr"
)
// ChromeOSVMRange returns the subset of the CGNAT IPv4 range used by
// ChromeOS to interconnect the host OS to containers and VMs. We
// avoid allocating Tailscale IPs from it, to avoid conflicts.
func ChromeOSVMRange() netaddr.IPPrefix {
chromeOSRange.Do(func() { mustPrefix(&chromeOSRange.v, "100.115.92.0/23") })
return chromeOSRange.v
}
var chromeOSRange oncePrefix
// CGNATRange returns the Carrier Grade NAT address range that
// is the superset range that Tailscale assigns out of.
// See https://tailscale.com/kb/1015/100.x-addresses.
// Note that Tailscale does not assign out of the ChromeOSVMRange.
func CGNATRange() netaddr.IPPrefix {
cgnatRange.Do(func() { mustPrefix(&cgnatRange.v, "100.64.0.0/10") })
return cgnatRange.v
}
var (
cgnatRange oncePrefix
ulaRange oncePrefix
ula4To6Range oncePrefix
)
// TailscaleServiceIP returns the listen address of services
// provided by Tailscale itself such as the MagicDNS proxy.
func TailscaleServiceIP() netaddr.IP {
serviceIP.Do(func() { mustIP(&serviceIP.v, "100.100.100.100") })
return serviceIP.v
}
var serviceIP onceIP
// IsTailscaleIP reports whether ip is an IP address in a range that
// Tailscale assigns from.
func IsTailscaleIP(ip netaddr.IP) bool {
if ip.Is4() {
return CGNATRange().Contains(ip) && !ChromeOSVMRange().Contains(ip)
}
return TailscaleULARange().Contains(ip)
}
// TailscaleULARange returns the IPv6 Unique Local Address range that
// is the superset range that Tailscale assigns out of.
func TailscaleULARange() netaddr.IPPrefix {
ulaRange.Do(func() { mustPrefix(&ulaRange.v, "fd7a:115c:a1e0::/48") })
return ulaRange.v
}
// Tailscale4To6Range returns the subset of TailscaleULARange used for
// auto-translated Tailscale ipv4 addresses.
func Tailscale4To6Range() netaddr.IPPrefix {
// This IP range has no significance, beyond being a subset of
// TailscaleULARange. The bits from /48 to /104 were picked at
// random.
ula4To6Range.Do(func() { mustPrefix(&ula4To6Range.v, "fd7a:115c:a1e0:ab12:4843:cd96:6200::/104") })
return ula4To6Range.v
}
// Tailscale4To6Placeholder returns an IP address that can be used as
// a source IP when one is required, but a netmap didn't provide
// any. This address never gets allocated by the 4-to-6 algorithm in
// control.
//
// Currently used to work around a Windows limitation when programming
// IPv6 routes in corner cases.
func Tailscale4To6Placeholder() netaddr.IP {
return Tailscale4To6Range().IP
}
// Tailscale4To6 returns a Tailscale IPv6 address that maps 1:1 to the
// given Tailscale IPv4 address. Returns a zero IP if ipv4 isn't a
// Tailscale IPv4 address.
func Tailscale4To6(ipv4 netaddr.IP) netaddr.IP {
if !ipv4.Is4() || !IsTailscaleIP(ipv4) {
return netaddr.IP{}
}
ret := Tailscale4To6Range().IP.As16()
v4 := ipv4.As4()
copy(ret[13:], v4[1:])
return netaddr.IPFrom16(ret)
}
func mustPrefix(v *netaddr.IPPrefix, prefix string) {
var err error
*v, err = netaddr.ParseIPPrefix(prefix)
if err != nil {
panic(err)
}
}
type oncePrefix struct {
sync.Once
v netaddr.IPPrefix
}
func mustIP(v *netaddr.IP, ip string) {
var err error
*v, err = netaddr.ParseIP(ip)
if err != nil {
panic(err)
}
}
type onceIP struct {
sync.Once
v netaddr.IP
}