100 lines
2.2 KiB
Go
100 lines
2.2 KiB
Go
|
// 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 system DNS config from /etc/resolv.conf
|
||
|
|
|
||
|
|
package dns
|
||
|
|
|
||
|
|
import (
|
||
|
|
"os"
|
||
|
|
"bufio"
|
||
|
|
"strconv"
|
||
|
|
"strings"
|
||
|
|
"net"
|
||
|
|
)
|
||
|
|
|
||
|
|
// See resolv.conf(5) on a Linux machine.
|
||
|
|
// Set the resolver configuration from a /etc/resolv.conf like file.
|
||
|
|
func (r *Resolver) FromFile(conf string) os.Error {
|
||
|
|
file, err := os.Open(conf, os.O_RDONLY, 0)
|
||
|
|
defer file.Close()
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
b := bufio.NewReader(file)
|
||
|
|
r.Servers = make([]string, 3)[0:0] // small, but the standard limit
|
||
|
|
r.Search = make([]string, 0)
|
||
|
|
r.Ndots = 1
|
||
|
|
r.Timeout = 5
|
||
|
|
r.Attempts = 2
|
||
|
|
for line, ok := b.ReadString('\n'); ok == nil; line, ok = b.ReadString('\n') {
|
||
|
|
f := strings.Fields(line)
|
||
|
|
if len(f) < 1 {
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
switch f[0] {
|
||
|
|
case "nameserver": // add one name server
|
||
|
|
a := r.Servers
|
||
|
|
n := len(a)
|
||
|
|
if len(f) > 1 && n < cap(a) {
|
||
|
|
// One more check: make sure server name is
|
||
|
|
// just an IP address. Otherwise we need DNS
|
||
|
|
// to look it up.
|
||
|
|
name := f[1]
|
||
|
|
switch len(net.ParseIP(name)) {
|
||
|
|
case 16:
|
||
|
|
name = "[" + name + "]"
|
||
|
|
fallthrough
|
||
|
|
case 4:
|
||
|
|
a = a[0 : n+1]
|
||
|
|
a[n] = name
|
||
|
|
r.Servers = a
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
case "domain": // set search path to just this domain
|
||
|
|
if len(f) > 1 {
|
||
|
|
r.Search = make([]string, 1)
|
||
|
|
r.Search[0] = f[1]
|
||
|
|
} else {
|
||
|
|
r.Search = make([]string, 0)
|
||
|
|
}
|
||
|
|
|
||
|
|
case "search": // set search path to given servers
|
||
|
|
r.Search = make([]string, len(f)-1)
|
||
|
|
for i := 0; i < len(r.Search); i++ {
|
||
|
|
r.Search[i] = f[i+1]
|
||
|
|
}
|
||
|
|
|
||
|
|
case "options": // magic options
|
||
|
|
for i := 1; i < len(f); i++ {
|
||
|
|
s := f[i]
|
||
|
|
switch {
|
||
|
|
case len(s) >= 6 && s[:6] == "ndots:":
|
||
|
|
n, _ := strconv.Atoi(s[6:])
|
||
|
|
if n < 1 {
|
||
|
|
n = 1
|
||
|
|
}
|
||
|
|
r.Ndots = n
|
||
|
|
case len(s) >= 8 && s[:8] == "timeout:":
|
||
|
|
n, _ := strconv.Atoi(s[8:])
|
||
|
|
if n < 1 {
|
||
|
|
n = 1
|
||
|
|
}
|
||
|
|
r.Timeout = n
|
||
|
|
case len(s) >= 8 && s[:9] == "attempts:":
|
||
|
|
n, _ := strconv.Atoi(s[9:])
|
||
|
|
if n < 1 {
|
||
|
|
n = 1
|
||
|
|
}
|
||
|
|
r.Attempts = n
|
||
|
|
case s == "rotate":
|
||
|
|
/* not imp */
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|