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tailscale/proxymap/proxymap.go

87 lines
2.5 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package proxymap contains a mapping table for ephemeral localhost ports used
// by tailscaled on behalf of remote Tailscale IPs for proxied connections.
package proxymap
import (
"net/netip"
"sync"
"time"
)
// Mapper tracks which localhost ip:ports correspond to which remote Tailscale
// IPs for connections proxied by tailscaled.
//
// This is then used (via the WhoIsIPPort method) by localhost applications to
// ask tailscaled (via the LocalAPI WhoIs method) the Tailscale identity that a
// given localhost:port corresponds to.
type Mapper struct {
mu sync.Mutex
m map[string]map[netip.AddrPort]netip.Addr // proto ("tcp", "udp") => ephemeral => tailscale IP
}
// RegisterIPPortIdentity registers a given node (identified by its
// Tailscale IP) as temporarily having the given IP:port for whois lookups.
//
// The IP:port is generally a localhost IP and an ephemeral port, used
// while proxying connections to localhost when tailscaled is running
// in netstack mode.
//
// The proto is the network protocol that is being proxied; it must be "tcp" or
// "udp" (not e.g. "tcp4", "udp6", etc.)
func (m *Mapper) RegisterIPPortIdentity(proto string, ipport netip.AddrPort, tsIP netip.Addr) {
m.mu.Lock()
defer m.mu.Unlock()
if m.m == nil {
m.m = make(map[string]map[netip.AddrPort]netip.Addr)
}
p, ok := m.m[proto]
if !ok {
p = make(map[netip.AddrPort]netip.Addr)
m.m[proto] = p
}
p[ipport] = tsIP
}
// UnregisterIPPortIdentity removes a temporary IP:port registration
// made previously by RegisterIPPortIdentity.
func (m *Mapper) UnregisterIPPortIdentity(proto string, ipport netip.AddrPort) {
m.mu.Lock()
defer m.mu.Unlock()
p := m.m[proto]
delete(p, ipport) // safe to delete from a nil map
}
var whoIsSleeps = [...]time.Duration{
0,
10 * time.Millisecond,
20 * time.Millisecond,
50 * time.Millisecond,
100 * time.Millisecond,
}
// WhoIsIPPort looks up an IP:port in the temporary registrations,
// and returns a matching Tailscale IP, if it exists.
func (m *Mapper) WhoIsIPPort(proto string, ipport netip.AddrPort) (tsIP netip.Addr, ok bool) {
// We currently have a registration race,
// https://github.com/tailscale/tailscale/issues/1616,
// so loop a few times for now waiting for the registration
// to appear.
// TODO(bradfitz,namansood): remove this once #1616 is fixed.
for _, d := range whoIsSleeps {
time.Sleep(d)
m.mu.Lock()
p, ok := m.m[proto]
if ok {
tsIP, ok = p[ipport]
}
m.mu.Unlock()
if ok {
return tsIP, true
}
}
return tsIP, false
}