83 lines
2.1 KiB
Go
83 lines
2.1 KiB
Go
// SPDX-License-Identifier: BSD-3-Clause
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//go:build windows
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package conf
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import (
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"fmt"
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"strings"
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"unsafe"
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"github.com/miekg/dns"
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"golang.org/x/sys/windows"
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)
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/*
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"Stolen" from
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https://gist.github.com/moloch--/9fb1c8497b09b45c840fe93dd23b1e98
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*/
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// GetDNSConfig (Windows version) returns all DNS server addresses using windows fuckery.
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//
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// Here be dragons.
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func GetDNSConfig() (*dns.ClientConfig, error) {
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length := uint32(100000)
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byt := make([]byte, length)
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// Windows is an utter fucking trash fire of an operating system.
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//nolint:gosec // This is necessary unless we want to drop 1.18
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if err := windows.GetAdaptersAddresses(windows.AF_UNSPEC, windows.GAA_FLAG_INCLUDE_PREFIX, 0, (*windows.IpAdapterAddresses)(unsafe.Pointer(&byt[0])), &length); err != nil {
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return nil, fmt.Errorf("config, windows: %w", err)
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}
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var addresses []*windows.IpAdapterAddresses
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//nolint:gosec // This is necessary unless we want to drop 1.18
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for addr := (*windows.IpAdapterAddresses)(unsafe.Pointer(&byt[0])); addr != nil; addr = addr.Next {
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addresses = append(addresses, addr)
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}
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resolvers := map[string]bool{}
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for _, addr := range addresses {
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for next := addr.FirstUnicastAddress; next != nil; next = next.Next {
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if addr.OperStatus != windows.IfOperStatusUp {
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continue
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}
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if next.Address.IP() != nil {
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for dnsServer := addr.FirstDnsServerAddress; dnsServer != nil; dnsServer = dnsServer.Next {
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ip := dnsServer.Address.IP()
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if ip.IsMulticast() || ip.IsLinkLocalMulticast() || ip.IsLinkLocalUnicast() || ip.IsUnspecified() {
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continue
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}
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if ip.To16() != nil && strings.HasPrefix(ip.To16().String(), "fec0:") {
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continue
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}
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resolvers[ip.String()] = true
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}
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break
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}
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}
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}
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// Take unique values only
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servers := []string{}
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for server := range resolvers {
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servers = append(servers, server)
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}
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// TODO: Make configurable, based on defaults in https://github.com/miekg/dns/blob/master/clientconfig.go
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return &dns.ClientConfig{
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Servers: servers,
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Search: []string{},
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Port: "53",
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Ndots: 1,
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Timeout: 5,
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Attempts: 1,
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}, nil
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}
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