1 // Copyright 2009 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
13 const cacheMaxAge = 5 * time.Second
15 func parseLiteralIP(addr string) string {
20 ip, zone = parseIPv6Zone(addr)
28 return ip.String() + "%" + zone
31 // hosts contains known host entries.
35 // Key for the list of literal IP addresses must be a host
36 // name. It would be part of DNS labels, a FQDN or an absolute
38 // For now the key is converted to lower case for convenience.
39 byName map[string][]string
41 // Key for the list of host names must be a literal IP address
42 // including IPv6 address with zone identifier.
43 // We don't support old-classful IP address notation.
44 byAddr map[string][]string
54 hp := testHookHostsPath
56 if now.Before(hosts.expire) && hosts.path == hp && len(hosts.byName) > 0 {
59 mtime, size, err := stat(hp)
60 if err == nil && hosts.path == hp && hosts.mtime.Equal(mtime) && hosts.size == size {
61 hosts.expire = now.Add(cacheMaxAge)
65 hs := make(map[string][]string)
66 is := make(map[string][]string)
68 if file, _ = open(hp); file == nil {
71 for line, ok := file.readLine(); ok; line, ok = file.readLine() {
72 if i := bytealg.IndexByteString(line, '#'); i >= 0 {
80 addr := parseLiteralIP(f[0])
84 for i := 1; i < len(f); i++ {
85 name := absDomainName([]byte(f[i]))
88 key := absDomainName(h)
89 hs[key] = append(hs[key], addr)
90 is[addr] = append(is[addr], name)
93 // Update the data cache.
94 hosts.expire = now.Add(cacheMaxAge)
103 // lookupStaticHost looks up the addresses for the given host from /etc/hosts.
104 func lookupStaticHost(host string) []string {
108 if len(hosts.byName) != 0 {
109 // TODO(jbd,bradfitz): avoid this alloc if host is already all lowercase?
110 // or linear scan the byName map if it's small enough?
111 lowerHost := []byte(host)
112 lowerASCIIBytes(lowerHost)
113 if ips, ok := hosts.byName[absDomainName(lowerHost)]; ok {
114 ipsCp := make([]string, len(ips))
122 // lookupStaticAddr looks up the hosts for the given address from /etc/hosts.
123 func lookupStaticAddr(addr string) []string {
127 addr = parseLiteralIP(addr)
131 if len(hosts.byAddr) != 0 {
132 if hosts, ok := hosts.byAddr[addr]; ok {
133 hostsCp := make([]string, len(hosts))