123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140 |
- // Copyright 2009 The Go 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 net
- import (
- "internal/bytealg"
- "sync"
- "time"
- )
- const cacheMaxAge = 5 * time.Second
- func parseLiteralIP(addr string) string {
- var ip IP
- var zone string
- ip = parseIPv4(addr)
- if ip == nil {
- ip, zone = parseIPv6Zone(addr)
- }
- if ip == nil {
- return ""
- }
- if zone == "" {
- return ip.String()
- }
- return ip.String() + "%" + zone
- }
- // hosts contains known host entries.
- var hosts struct {
- sync.Mutex
- // Key for the list of literal IP addresses must be a host
- // name. It would be part of DNS labels, a FQDN or an absolute
- // FQDN.
- // For now the key is converted to lower case for convenience.
- byName map[string][]string
- // Key for the list of host names must be a literal IP address
- // including IPv6 address with zone identifier.
- // We don't support old-classful IP address notation.
- byAddr map[string][]string
- expire time.Time
- path string
- mtime time.Time
- size int64
- }
- func readHosts() {
- now := time.Now()
- hp := testHookHostsPath
- if now.Before(hosts.expire) && hosts.path == hp && len(hosts.byName) > 0 {
- return
- }
- mtime, size, err := stat(hp)
- if err == nil && hosts.path == hp && hosts.mtime.Equal(mtime) && hosts.size == size {
- hosts.expire = now.Add(cacheMaxAge)
- return
- }
- hs := make(map[string][]string)
- is := make(map[string][]string)
- var file *file
- if file, _ = open(hp); file == nil {
- return
- }
- for line, ok := file.readLine(); ok; line, ok = file.readLine() {
- if i := bytealg.IndexByteString(line, '#'); i >= 0 {
- // Discard comments.
- line = line[0:i]
- }
- f := getFields(line)
- if len(f) < 2 {
- continue
- }
- addr := parseLiteralIP(f[0])
- if addr == "" {
- continue
- }
- for i := 1; i < len(f); i++ {
- name := absDomainName(f[i])
- h := []byte(f[i])
- lowerASCIIBytes(h)
- key := absDomainName(string(h))
- hs[key] = append(hs[key], addr)
- is[addr] = append(is[addr], name)
- }
- }
- // Update the data cache.
- hosts.expire = now.Add(cacheMaxAge)
- hosts.path = hp
- hosts.byName = hs
- hosts.byAddr = is
- hosts.mtime = mtime
- hosts.size = size
- file.close()
- }
- // lookupStaticHost looks up the addresses for the given host from /etc/hosts.
- func lookupStaticHost(host string) []string {
- hosts.Lock()
- defer hosts.Unlock()
- readHosts()
- if len(hosts.byName) != 0 {
- if hasUpperCase(host) {
- lowerHost := []byte(host)
- lowerASCIIBytes(lowerHost)
- host = string(lowerHost)
- }
- if ips, ok := hosts.byName[absDomainName(host)]; ok {
- ipsCp := make([]string, len(ips))
- copy(ipsCp, ips)
- return ipsCp
- }
- }
- return nil
- }
- // lookupStaticAddr looks up the hosts for the given address from /etc/hosts.
- func lookupStaticAddr(addr string) []string {
- hosts.Lock()
- defer hosts.Unlock()
- readHosts()
- addr = parseLiteralIP(addr)
- if addr == "" {
- return nil
- }
- if len(hosts.byAddr) != 0 {
- if hosts, ok := hosts.byAddr[addr]; ok {
- hostsCp := make([]string, len(hosts))
- copy(hostsCp, hosts)
- return hostsCp
- }
- }
- return nil
- }
|