awl/conf/win.go
Sam Therapy 0b042af3e2
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fix(win): Fix occasional buffer overflows (#166)
This fixes a problem I have had where I get the following message sometimes:
Error: config, windows: The file name is too long.

Delv says it is a buffer overflow so this fixes it at the cost of just allocating more memory.

TODO: Make actually good

Reviewed-on: #166
Reviewed-by: grumbulon <grumbulon@grumbulon.xyz>
2022-12-10 17:51:00 +00:00

82 lines
2.1 KiB
Go

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