mirror of https://go.googlesource.com/go
69 lines
1.6 KiB
Go
69 lines
1.6 KiB
Go
// Copyright 2022 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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package net
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import (
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"internal/syscall/windows"
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"syscall"
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"time"
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)
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func dnsReadConfig(ignoredFilename string) (conf *dnsConfig) {
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conf = &dnsConfig{
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ndots: 1,
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timeout: 5 * time.Second,
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attempts: 2,
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}
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defer func() {
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if len(conf.servers) == 0 {
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conf.servers = defaultNS
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}
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}()
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aas, err := adapterAddresses()
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if err != nil {
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return
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}
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for _, aa := range aas {
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// Only take interfaces whose OperStatus is IfOperStatusUp(0x01) into DNS configs.
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if aa.OperStatus != windows.IfOperStatusUp {
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continue
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}
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// Only take interfaces which have at least one gateway
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if aa.FirstGatewayAddress == nil {
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continue
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}
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for dns := aa.FirstDnsServerAddress; dns != nil; dns = dns.Next {
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sa, err := dns.Address.Sockaddr.Sockaddr()
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if err != nil {
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continue
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}
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var ip IP
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switch sa := sa.(type) {
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case *syscall.SockaddrInet4:
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ip = IPv4(sa.Addr[0], sa.Addr[1], sa.Addr[2], sa.Addr[3])
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case *syscall.SockaddrInet6:
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ip = make(IP, IPv6len)
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copy(ip, sa.Addr[:])
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if ip[0] == 0xfe && ip[1] == 0xc0 {
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// fec0/10 IPv6 addresses are site local anycast DNS
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// addresses Microsoft sets by default if no other
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// IPv6 DNS address is set. Site local anycast is
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// deprecated since 2004, see
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// https://datatracker.ietf.org/doc/html/rfc3879
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continue
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}
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default:
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// Unexpected type.
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continue
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}
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conf.servers = append(conf.servers, JoinHostPort(ip.String(), "53"))
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}
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}
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return conf
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}
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