dnscontrol/pkg/powershell/middleware/utf8.go

// Copyright (c) 2017 Gorillalabs. All rights reserved.

package middleware

import (
	"encoding/base64"
	"fmt"

	"github.com/StackExchange/dnscontrol/v4/pkg/powershell/utils"
)

// utf8 implements a primitive middleware that encodes all outputs
// as base64 to prevent encoding issues between remote PowerShell
// shells and the receiver. Just setting $OutputEncoding does not
// work reliably enough, sadly.
type utf8 struct {
	upstream Middleware
	wrapper  string
}

func NewUTF8(upstream Middleware) (Middleware, error) {
	wrapper := "goUTF8" + utils.CreateRandomString(8)

	_, _, err := upstream.Execute(fmt.Sprintf(`function %s { process { if ($_) { [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes($_)) } else { '' } } }`, wrapper))

	return &utf8{upstream, wrapper}, err
}

func (u *utf8) Execute(cmd string) (string, string, error) {
	// Out-String to concat all lines into a single line,
	// Write-Host to prevent line breaks at the "window width"
	cmd = fmt.Sprintf(`%s | Out-String | %s | Write-Host`, cmd, u.wrapper)

	stdout, stderr, err := u.upstream.Execute(cmd)
	if err != nil {
		return stdout, stderr, err
	}

	decoded, err := base64.StdEncoding.DecodeString(stdout)
	if err != nil {
		return stdout, stderr, err
	}

	return string(decoded), stderr, nil
}

func (u *utf8) Exit() {
	u.upstream.Exit()
}