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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
package conf
import (
"fmt"
"golang.org/x/sys/windows"
"log"
"net"
"syscall"
"time"
"unsafe"
)
//sys internetGetConnectedState(flags *uint32, reserved uint32) (connected bool) = wininet.InternetGetConnectedState
//sys getTickCount64() (ms uint64) = kernel32.GetTickCount64
func resolveHostname(name string) (resolvedIpString string, err error) {
const maxTries = 10
systemJustBooted := getTickCount64() <= uint64(time.Minute*4/time.Millisecond)
for i := 0; i < maxTries; i++ {
resolvedIpString, err = resolveHostnameOnce(name)
if err == nil {
return
}
if err == windows.WSATRY_AGAIN {
log.Printf("Temporary DNS error when resolving %s, sleeping for 4 seconds", name)
time.Sleep(time.Second * 4)
continue
}
var state uint32
if err == windows.WSAHOST_NOT_FOUND && systemJustBooted && !internetGetConnectedState(&state, 0) {
log.Printf("Host not found when resolving %s, but no Internet connection available, sleeping for 4 seconds", name)
time.Sleep(time.Second * 4)
continue
}
return
}
return
}
func resolveHostnameOnce(name string) (resolvedIpString string, err error) {
hints := windows.AddrinfoW{
Family: windows.AF_UNSPEC,
Socktype: windows.SOCK_DGRAM,
Protocol: windows.IPPROTO_IP,
}
var result *windows.AddrinfoW
name16, err := windows.UTF16PtrFromString(name)
if err != nil {
return
}
err = windows.GetAddrInfoW(name16, nil, &hints, &result)
if err != nil {
return
}
if result == nil {
err = windows.WSAHOST_NOT_FOUND
return
}
defer windows.FreeAddrInfoW(result)
ipv6 := ""
for ; result != nil; result = result.Next {
addr := unsafe.Pointer(result.Addr)
switch result.Family {
case windows.AF_INET:
a := (*syscall.RawSockaddrInet4)(addr).Addr
return net.IP{a[0], a[1], a[2], a[3]}.String(), nil
case windows.AF_INET6:
if len(ipv6) != 0 {
continue
}
a := (*syscall.RawSockaddrInet6)(addr).Addr
ipv6 = net.IP{a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14], a[15]}.String()
scope := uint32((*syscall.RawSockaddrInet6)(addr).Scope_id)
if scope != 0 {
ipv6 += fmt.Sprintf("%%%d", scope)
}
}
}
if len(ipv6) != 0 {
return ipv6, nil
}
err = windows.WSAHOST_NOT_FOUND
return
}
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