golang下，调用Win的API，DnsQueryConfig，一直不成功，高手可以指点一下么【已解决，代码在文章结尾】

DnsQueryConfig，此API的功能是，获取本机的DNS，API的官方文档在这：

https://docs.microsoft.com/en-us/windows/win32/api/windns/nf-windns-dnsqueryconfig

在项目github.com/kbinani/win下新建了文件dnsapi.go，代码如下：

// This file was automatically generated by https://github.com/kbinani/win/blob/generator/internal/cmd/gen/gen.go
// go run internal/cmd/gen/gen.go

// +build windows

package win

import "unsafe"

var (
    // Library
    libdnsapi uintptr

    // function
    dnsQueryConfig  uintptr
)

type DNS_CONFIG_TYPE uint32

type IP4_ARRAY struct {
    AddrCount   DWORD
    IP4_ADDRESS [0]IP_ADDRESS_STRING
}

type PIP4_ARRAY *IP4_ARRAY

func init(){
    // Library
    libdnsapi = doLoadLibrary("Dnsapi.dll")

    // Functions
    dnsQueryConfig = doGetProcAddress(libdnsapi, "DnsQueryConfig")
}

func DnsQueryConfig(config DNS_CONFIG_TYPE, flag DWORD, pwsAdapterName PCWSTR, pReserved PVOID, pBuffer PVOID, pBufLen DWORD_PTR) int32 {
    ret1 := syscall6(dnsQueryConfig,
        6,
        uintptr(unsafe.Pointer(&config)),
        uintptr(unsafe.Pointer(&flag)),
        uintptr(unsafe.Pointer(pwsAdapterName)),
        uintptr(pReserved),
        uintptr(pBuffer),
        uintptr(unsafe.Pointer(pBufLen)),
        )
    return int32(ret1)
}

在自己的项目中，代码如下：

package main

import (
    "fmt"
    "github.com/kbinani/win"
    "unsafe"
)

func main(){
    // func DnsQueryConfig(config DNS_CONFIG_TYPE, flag DWORD, pwsAdapterName PCWSTR, pReserved PVOID, pBuffer PVOID, pBufLen DWORD_PTR) int32 {
    config := win.DNS_CONFIG_TYPE(6)
    flag := win.DWORD(0)
    pwsAdapterName := win.PCWSTR(nil)
    pReserved := win.PVOID(unsafe.Pointer(nil))
    buffer := win.IP4_ARRAY{}
    a := win.PVOID(unsafe.Pointer(&buffer))
    l := uint32(unsafe.Sizeof(buffer))
    pBufLen := win.DWORD_PTR(unsafe.Pointer(&l))
    //bufferp := win.From
    r := win.DnsQueryConfig(config, flag, pwsAdapterName, pReserved, a, pBufLen)
    fmt.Println(r)
}

运行的结果始终返回代码87：

87

Process finished with exit code 0

我查了下此87代表的意思是无效的参数：

#define ERROR_INVALID_PARAMETER                        87L

还请大神指点，哪儿出错了，非常感谢

这个问题解决了：

package main

import (
    "fmt"
    "golang.org/x/sys/windows"
    "net"
    "strings"
    "unsafe"
)

const (
    DnsConfigDnsServerList int32 = 6
)

type char byte
type IpAddressString struct {
    DNS [4 * 10]char
}

type Ip4Array struct {
    AddrCount  uint32
    Ip4Address [1]IpAddressString
}

func main() {
    fmt.Println(dns())
}

func dns() []string {
    dns := []string{}
    dnsapi := windows.NewLazyDLL("Dnsapi.dll")
    dnsQuery := dnsapi.NewProc("DnsQueryConfig")
    bufferBytes := make([]byte, 60)
loop:
    buffer := (*Ip4Array)(unsafe.Pointer(&bufferBytes[0]))
    blen := len(bufferBytes)
    r1, _, _ := dnsQuery.Call(uintptr(DnsConfigDnsServerList), uintptr(0), uintptr(0), uintptr(0), uintptr(unsafe.Pointer(&bufferBytes[0])), uintptr(unsafe.Pointer(&blen)))
    if r1 == 234 {
        bufferBytes = make([]byte, blen)
        goto loop
    } else if r1 == 0 {

    } else {
        return dns 
    }
    for i := uint32(1); i <= buffer.AddrCount; i++ {
        right := i * 4
        left := right - 4
        tmpChars := buffer.Ip4Address[0].DNS[left:right]
        tmpStr := []string{}
        for j := 0; j < len(tmpChars); j++ {
            tmpStr = append(tmpStr, fmt.Sprint(tmpChars[j]))
        }
        tmpDNS := strings.Join(tmpStr, ".")
        pDns := net.ParseIP(tmpDNS)
        if pDns == nil {
            continue
        }
        if !pDns.IsGlobalUnicast() {
            continue
        }
        dns = append(dns, tmpDNS)
    }
    return dns
}

运行结果：

[10.198.1.1 114.114.114.114 114.114.115.115 8.8.8.8 218.85.157.99 218.85.152.99]