mirror of
https://github.com/tailscale/tailscale.git
synced 2024-11-26 11:35:35 +00:00
119 lines
2.6 KiB
Go
119 lines
2.6 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tsdns
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import (
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"fmt"
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"sort"
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"strings"
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"inet.af/netaddr"
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)
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// Map is all the data Resolver needs to resolve DNS queries within the Tailscale network.
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type Map struct {
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// nameToIP is a mapping of Tailscale domain names to their IP addresses.
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// For example, monitoring.tailscale.us -> 100.64.0.1.
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nameToIP map[string]netaddr.IP
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// names are the keys of nameToIP in sorted order.
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names []string
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}
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// NewMap returns a new Map with name to address mapping given by nameToIP.
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func NewMap(nameToIP map[string]netaddr.IP) *Map {
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names := make([]string, 0, len(nameToIP))
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for name := range nameToIP {
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names = append(names, name)
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}
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sort.Strings(names)
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return &Map{
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nameToIP: nameToIP,
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names: names,
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}
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}
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func printSingleNameIP(buf *strings.Builder, name string, ip netaddr.IP) {
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// Output width is exactly 80 columns.
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fmt.Fprintf(buf, "%s\t%s\n", name, ip)
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}
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func (m *Map) Pretty() string {
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buf := new(strings.Builder)
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for _, name := range m.names {
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printSingleNameIP(buf, name, m.nameToIP[name])
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}
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return buf.String()
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}
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func (m *Map) PrettyDiffFrom(old *Map) string {
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var (
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oldNameToIP map[string]netaddr.IP
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newNameToIP map[string]netaddr.IP
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oldNames []string
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newNames []string
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)
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if old != nil {
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oldNameToIP = old.nameToIP
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oldNames = old.names
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}
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if m != nil {
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newNameToIP = m.nameToIP
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newNames = m.names
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}
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buf := new(strings.Builder)
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for len(oldNames) > 0 && len(newNames) > 0 {
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var name string
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newName, oldName := newNames[0], oldNames[0]
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switch {
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case oldName < newName:
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name = oldName
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oldNames = oldNames[1:]
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case oldName > newName:
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name = newName
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newNames = newNames[1:]
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case oldNames[0] == newNames[0]:
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name = oldNames[0]
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oldNames = oldNames[1:]
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newNames = newNames[1:]
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}
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ipOld, inOld := oldNameToIP[name]
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ipNew, inNew := newNameToIP[name]
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switch {
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case !inOld:
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buf.WriteByte('+')
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printSingleNameIP(buf, name, ipNew)
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case !inNew:
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buf.WriteByte('-')
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printSingleNameIP(buf, name, ipOld)
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case ipOld != ipNew:
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buf.WriteByte('-')
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printSingleNameIP(buf, name, ipOld)
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buf.WriteByte('+')
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printSingleNameIP(buf, name, ipNew)
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}
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}
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for _, name := range oldNames {
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if _, ok := newNameToIP[name]; !ok {
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buf.WriteByte('-')
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printSingleNameIP(buf, name, oldNameToIP[name])
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}
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}
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for _, name := range newNames {
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if _, ok := oldNameToIP[name]; !ok {
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buf.WriteByte('+')
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printSingleNameIP(buf, name, newNameToIP[name])
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}
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}
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return buf.String()
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}
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