102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
//go:build windows
|
|
|
|
package dns
|
|
|
|
import (
|
|
"fmt"
|
|
"net"
|
|
"os"
|
|
"syscall"
|
|
"unsafe"
|
|
|
|
"golang.org/x/sys/windows"
|
|
)
|
|
|
|
type dnsConfig struct {
|
|
servers []string // server addresses (in host:port form) to use
|
|
}
|
|
|
|
func loadSystemResolver() (clients []dnsClient, err error) {
|
|
content, err := dnsReadConfig()
|
|
if err != nil {
|
|
err = fmt.Errorf("failed to read system DNS: %w", err)
|
|
}
|
|
nameservers := content.servers
|
|
if len(nameservers) == 0 {
|
|
return
|
|
}
|
|
servers := make([]NameServer, 0, len(nameservers))
|
|
for _, addr := range nameservers {
|
|
servers = append(servers, NameServer{
|
|
Addr: addr,
|
|
Net: "udp",
|
|
})
|
|
}
|
|
return transform(servers, nil), nil
|
|
}
|
|
|
|
func dnsReadConfig() (conf *dnsConfig, err error) {
|
|
conf = &dnsConfig{}
|
|
aas, err := adapterAddresses()
|
|
if err != nil {
|
|
return conf, err
|
|
}
|
|
for _, aa := range aas {
|
|
for dns := aa.FirstDnsServerAddress; dns != nil; dns = dns.Next {
|
|
sa, err := dns.Address.Sockaddr.Sockaddr()
|
|
if err != nil {
|
|
continue
|
|
}
|
|
var ip net.IP
|
|
switch sa := sa.(type) {
|
|
case *syscall.SockaddrInet4:
|
|
ip = net.IPv4(sa.Addr[0], sa.Addr[1], sa.Addr[2], sa.Addr[3])
|
|
case *syscall.SockaddrInet6:
|
|
//ip = make(net.IP, net.IPv6len)
|
|
//copy(ip, sa.Addr[:])
|
|
//if ip[0] == 0xfe && ip[1] == 0xc0 {
|
|
// // Ignore these fec0/10 ones. Windows seems to
|
|
// // populate them as defaults on its misc rando
|
|
// // interfaces.
|
|
// continue
|
|
//}
|
|
continue
|
|
default:
|
|
// Unexpected type.
|
|
continue
|
|
}
|
|
conf.servers = append(conf.servers, net.JoinHostPort(ip.String(), "53"))
|
|
}
|
|
}
|
|
return conf, nil
|
|
}
|
|
|
|
// adapterAddresses returns a list of IP adapter and address
|
|
// structures. The structure contains an IP adapter and flattened
|
|
// multiple IP addresses including unicast, anycast and multicast
|
|
// addresses.
|
|
func adapterAddresses() ([]*windows.IpAdapterAddresses, error) {
|
|
var b []byte
|
|
l := uint32(15000) // recommended initial size
|
|
for {
|
|
b = make([]byte, l)
|
|
err := windows.GetAdaptersAddresses(syscall.AF_UNSPEC, windows.GAA_FLAG_INCLUDE_PREFIX, 0, (*windows.IpAdapterAddresses)(unsafe.Pointer(&b[0])), &l)
|
|
if err == nil {
|
|
if l == 0 {
|
|
return nil, nil
|
|
}
|
|
break
|
|
}
|
|
if err.(syscall.Errno) != syscall.ERROR_BUFFER_OVERFLOW {
|
|
return nil, os.NewSyscallError("getadaptersaddresses", err)
|
|
}
|
|
if l <= uint32(len(b)) {
|
|
return nil, os.NewSyscallError("getadaptersaddresses", err)
|
|
}
|
|
}
|
|
var aas []*windows.IpAdapterAddresses
|
|
for aa := (*windows.IpAdapterAddresses)(unsafe.Pointer(&b[0])); aa != nil; aa = aa.Next {
|
|
aas = append(aas, aa)
|
|
}
|
|
return aas, nil
|
|
}
|