You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: basic.go
    path of file: ./repos/gogs/internal/authutil
    
    the code of the file until where you have to start completion: // Copyright 2020 The Gogs Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package authutil

import (
	"encoding/base64"
	"net/http"
	"strings"
)

// DecodeBasic extracts username and password from given header using HTTP Basic Auth.
/
    
func DecodeBasic(header http.Header) (username, password string) {
	if len(header) == 0 {
		return "", ""
	}

	fields := strings.Fields(header.Get("Authorization"))
	if len(fields) != 2 || fields[0] != "Basic" {
		return "", ""
	}

	p, err := base64.StdEncoding.DecodeString(fields[1])
	if err != nil {
		return "", ""
	}

	creds := strings.SplitN(string(p), ":", 2)
	if len(creds) == 1 {
		return creds[0], ""
	}
	return creds[0], creds[1]
}