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Copy pathhosts.go
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319 lines (253 loc) · 6.36 KB
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Copy pathhosts.go
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319 lines (253 loc) · 6.36 KB
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// Copyright 2016-2017 VMware, Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package etcconf
import (
"bytes"
"fmt"
"net"
"os"
"sort"
"strings"
"sync"
log "github.com/Sirupsen/logrus"
)
type Hosts interface {
Conf
SetHost(hostname string, ip net.IP)
RemoveHost(hostname string)
RemoveAll()
HostIP(hostname string) []net.IP
}
type hostEntry struct {
IP net.IP
Hostnames []string
newAddr bool
}
func (e *hostEntry) String() string {
return fmt.Sprintf("%s %s", e.IP, strings.Join(e.Hostnames, " "))
}
func (e *hostEntry) addNames(names ...string) string {
e.Hostnames = append(e.Hostnames, names...)
sort.Strings(e.Hostnames)
return e.IP.String() + " " + strings.Join(e.Hostnames, " ")
}
func (e *hostEntry) setAddress(ip net.IP) {
if e.IP != nil {
hostnames := strings.Join(e.Hostnames, " ")
log.Infof("Changing IP address: %s -> %s", e.IP.String(), ip.String())
log.Infof("IP change impacts the following hostnames: %s", hostnames)
if e.newAddr {
log.Warn("Address has changed more than once since last load, implying a configuration race")
}
e.newAddr = true
}
e.IP = ip
}
type hosts struct {
sync.Mutex
EntryConsumer
hostsIPv4 map[string]*hostEntry
hostsIPv6 map[string]*hostEntry
entries map[string]*hostEntry
dirty bool
path string
}
type hostsWalker struct {
entries []*hostEntry
i int
}
func (w *hostsWalker) HasNext() bool {
return w.i < len(w.entries)
}
func (w *hostsWalker) Next() string {
s := w.entries[w.i].String()
w.i++
return s
}
func NewHosts(path string) Hosts {
return newHosts(path)
}
func newHosts(path string) *hosts {
if path == "" {
path = HostsPath
}
return &hosts{
path: path,
hostsIPv4: make(map[string]*hostEntry),
hostsIPv6: make(map[string]*hostEntry),
entries: make(map[string]*hostEntry),
}
}
func (h *hosts) ConsumeEntry(t string) error {
h.Lock()
defer h.Unlock()
fs := strings.Fields(t)
if len(fs) < 2 {
log.Warnf("ignoring incomplete line %q", t)
return nil
}
ip := net.ParseIP(fs[0])
if ip == nil {
log.Warnf("ignoring line %q due to invalid ip address", t)
return nil
}
for _, hs := range fs[1:] {
h.setHost(hs, ip)
}
return nil
}
// Needs to ensure that host entries don't occur twice, and that we have stable reconsiliation if they do
func (h *hosts) Load() error {
h.Lock()
defer h.Unlock()
newHosts := newHosts(h.path)
if err := load(h.path, newHosts); err != nil {
return err
}
h.hostsIPv4 = newHosts.hostsIPv4
h.hostsIPv6 = newHosts.hostsIPv6
h.entries = newHosts.entries
h.dirty = false
return nil
}
// Seed pulls replaces the current state with that from the provided hosts
// It _does not_ perform a deep copy so performs a Save immediately.
func (h *hosts) Copy(conf Conf) error {
// straight up panic if not the appropriate type
existing := conf.(*hosts)
existing.Lock()
defer existing.Unlock()
h.hostsIPv4 = existing.hostsIPv4
h.hostsIPv6 = existing.hostsIPv6
h.entries = existing.entries
h.dirty = true
return h.Save()
}
// ensure hostname is associated with localhost
func (h *hosts) Save() error {
h.Lock()
defer h.Unlock()
if !h.dirty {
log.Debugf("skipping writing file since there are no new entries")
return nil
}
var entries []*hostEntry
for _, v := range h.entries {
entries = append(entries, v)
}
if err := save(h.path, &hostsWalker{entries: entries}); err != nil {
return err
}
// make sure the file is readable
// #nosec: Expect file permissions to be 0600 or less
if err := os.Chmod(h.path, 0644); err != nil {
return err
}
h.dirty = false
return nil
}
func (h *hosts) SetHost(hostname string, ip net.IP) {
h.Lock()
defer h.Unlock()
h.setHost(hostname, ip)
}
func (h *hosts) setHost(hostname string, ip net.IP) {
h.dirty = true
if ip == nil {
return
}
// what type of address is it?
hostmap := h.hostsIPv6
ipv4 := ip.To4()
if ipv4 != nil {
// this drops any leading garbage in the array so that byte comparisons work as
// expected
ip = ipv4
hostmap = h.hostsIPv4
}
hentry := hostmap[hostname]
ientry := h.entries[ip.String()]
if hentry != nil {
// existing entry with no changes
if bytes.Equal(hentry.IP, ip) {
h.dirty = false
return
}
// existing hostname with a new address - change address for all assocated hostnames
hentry.setAddress(ip)
return
}
// completely new entry for this ip address type
if ientry == nil {
entry := &hostEntry{
IP: ip,
Hostnames: []string{hostname},
}
h.entries[ip.String()] = entry
hostmap[hostname] = entry
return
}
// add the hostname indexed IP record
ientry.Hostnames = append(ientry.Hostnames, hostname)
hostmap[hostname] = ientry
return
}
func (h *hosts) RemoveHost(hostname string) {
h.Lock()
defer h.Unlock()
for _, hostmap := range []map[string]*hostEntry{h.hostsIPv4, h.hostsIPv6} {
entry := hostmap[hostname]
if entry == nil {
continue
}
h.dirty = true
delete(hostmap, hostname)
if len(entry.Hostnames) < 2 {
log.Infof("Removing hostname and address: %s (%s)", hostname, entry.IP.String())
delete(h.entries, entry.IP.String())
continue
}
var remaining []string
for i := range entry.Hostnames {
if entry.Hostnames[i] == hostname {
remaining = entry.Hostnames[:i]
remaining = append(remaining, entry.Hostnames[i+1:]...)
}
}
entry.Hostnames = remaining
}
}
func (h *hosts) RemoveAll() {
h.Lock()
defer h.Unlock()
h.dirty = len(h.hostsIPv4) > 0 || len(h.hostsIPv6) > 0
h.hostsIPv4 = make(map[string]*hostEntry)
h.hostsIPv6 = make(map[string]*hostEntry)
h.entries = make(map[string]*hostEntry)
}
func (h *hosts) HostIP(hostname string) []net.IP {
h.Lock()
defer h.Unlock()
var ips []net.IP
if ipv4, ok := h.hostsIPv4[hostname]; ok {
ips = append(ips, ipv4.IP)
}
if ipv6, ok := h.hostsIPv6[hostname]; ok {
ips = append(ips, ipv6.IP)
}
return ips
}
func (h *hosts) Path() string {
return h.path
}