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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/go/net/hosts.go
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Diffstat (limited to 'libgo/go/net/hosts.go')
-rw-r--r--libgo/go/net/hosts.go86
1 files changed, 86 insertions, 0 deletions
diff --git a/libgo/go/net/hosts.go b/libgo/go/net/hosts.go
new file mode 100644
index 000000000..8525f578d
--- /dev/null
+++ b/libgo/go/net/hosts.go
@@ -0,0 +1,86 @@
+// 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.
+
+// Read static host/IP entries from /etc/hosts.
+
+package net
+
+import (
+ "os"
+ "sync"
+)
+
+const cacheMaxAge = int64(300) // 5 minutes.
+
+// hostsPath points to the file with static IP/address entries.
+var hostsPath = "/etc/hosts"
+
+// Simple cache.
+var hosts struct {
+ sync.Mutex
+ byName map[string][]string
+ byAddr map[string][]string
+ time int64
+ path string
+}
+
+func readHosts() {
+ now, _, _ := os.Time()
+ hp := hostsPath
+ if len(hosts.byName) == 0 || hosts.time+cacheMaxAge <= now || hosts.path != hp {
+ 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 := byteIndex(line, '#'); i >= 0 {
+ // Discard comments.
+ line = line[0:i]
+ }
+ f := getFields(line)
+ if len(f) < 2 || ParseIP(f[0]) == nil {
+ continue
+ }
+ for i := 1; i < len(f); i++ {
+ h := f[i]
+ hs[h] = append(hs[h], f[0])
+ is[f[0]] = append(is[f[0]], h)
+ }
+ }
+ // Update the data cache.
+ hosts.time, _, _ = os.Time()
+ hosts.path = hp
+ hosts.byName = hs
+ hosts.byAddr = is
+ file.close()
+ }
+}
+
+// lookupStaticHosts 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 ips, ok := hosts.byName[host]; ok {
+ return ips
+ }
+ }
+ return nil
+}
+
+// rlookupStaticHosts looks up the hosts for the given address from /etc/hosts.
+func lookupStaticAddr(addr string) []string {
+ hosts.Lock()
+ defer hosts.Unlock()
+ readHosts()
+ if len(hosts.byAddr) != 0 {
+ if hosts, ok := hosts.byAddr[addr]; ok {
+ return hosts
+ }
+ }
+ return nil
+}