af146490bb
It is not needed due to the removal of the ctx field.
Reviewed-on: https://go-review.googlesource.com/16525
From-SVN: r229616
121 lines
3.1 KiB
Go
121 lines
3.1 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build darwin dragonfly freebsd linux netbsd openbsd solaris
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// Read system DNS config from /etc/resolv.conf
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package net
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var defaultNS = []string{"127.0.0.1", "::1"}
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type dnsConfig struct {
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servers []string // servers to use
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search []string // suffixes to append to local name
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ndots int // number of dots in name to trigger absolute lookup
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timeout int // seconds before giving up on packet
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attempts int // lost packets before giving up on server
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rotate bool // round robin among servers
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unknownOpt bool // anything unknown was encountered
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lookup []string // OpenBSD top-level database "lookup" order
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err error // any error that occurs during open of resolv.conf
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}
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// See resolv.conf(5) on a Linux machine.
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// TODO(rsc): Supposed to call uname() and chop the beginning
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// of the host name to get the default search domain.
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func dnsReadConfig(filename string) *dnsConfig {
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conf := &dnsConfig{
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ndots: 1,
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timeout: 5,
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attempts: 2,
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}
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file, err := open(filename)
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if err != nil {
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conf.servers = defaultNS
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conf.err = err
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return conf
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}
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defer file.close()
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for line, ok := file.readLine(); ok; line, ok = file.readLine() {
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if len(line) > 0 && (line[0] == ';' || line[0] == '#') {
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// comment.
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continue
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}
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f := getFields(line)
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if len(f) < 1 {
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continue
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}
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switch f[0] {
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case "nameserver": // add one name server
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if len(f) > 1 && len(conf.servers) < 3 { // small, but the standard limit
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// One more check: make sure server name is
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// just an IP address. Otherwise we need DNS
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// to look it up.
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if parseIPv4(f[1]) != nil {
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conf.servers = append(conf.servers, f[1])
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} else if ip, _ := parseIPv6(f[1], true); ip != nil {
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conf.servers = append(conf.servers, f[1])
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}
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}
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case "domain": // set search path to just this domain
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if len(f) > 1 {
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conf.search = []string{f[1]}
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}
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case "search": // set search path to given servers
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conf.search = make([]string, len(f)-1)
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for i := 0; i < len(conf.search); i++ {
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conf.search[i] = f[i+1]
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}
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case "options": // magic options
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for _, s := range f[1:] {
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switch {
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case hasPrefix(s, "ndots:"):
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n, _, _ := dtoi(s, 6)
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if n < 1 {
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n = 1
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}
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conf.ndots = n
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case hasPrefix(s, "timeout:"):
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n, _, _ := dtoi(s, 8)
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if n < 1 {
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n = 1
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}
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conf.timeout = n
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case hasPrefix(s, "attempts:"):
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n, _, _ := dtoi(s, 9)
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if n < 1 {
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n = 1
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}
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conf.attempts = n
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case s == "rotate":
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conf.rotate = true
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default:
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conf.unknownOpt = true
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}
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}
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case "lookup":
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// OpenBSD option:
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// http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man5/resolv.conf.5
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// "the legal space-separated values are: bind, file, yp"
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conf.lookup = f[1:]
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default:
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conf.unknownOpt = true
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}
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}
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if len(conf.servers) == 0 {
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conf.servers = defaultNS
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}
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return conf
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}
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func hasPrefix(s, prefix string) bool {
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return len(s) >= len(prefix) && s[:len(prefix)] == prefix
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}
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