HttpServerUtility.UrlTokenEncode替换netstandard

Question

我移植一个项目的目标net472来netstandard.System.Web我坚持的最后一个依赖是HttpServerUtility.UrlTokenEncode(Byte[]).

我发现Microsoft.AspNetCore.WebUtilities,包含Base64UrlTextEncoder和WebEncoders,但是它们与UrlTokenEncode/ 不可互换Decode,因为它追加/期望最后的=填充字符数,例如:

var data = Encoding.UTF8.GetBytes("SO");
Convert.ToBase64String(data);              // U08=
HttpServerUtility.UrlTokenEncode(data);    // U081 - this is what's expected and 
                                           // the only thing UrlTokenDecode can handle
Base64UrlTextEncoder.Encode(data);         // U08
WebEncoders.Base64UrlEncode(data);         // U08

据我所知,没有其他差异(我用随机字符串运行测试),但它也引入了一些其他依赖项(Microsoft.Net.Http.Headers和Microsoft.Extensions.Primitives),我不知道真的需要在那个项目中.

是否有任何nuget包装与直接替换？我想自己实现这个,如果没有.

Answer 1

对于那些寻找这种已删除实用工具方法的答案并希望在其中迁移旧版应用程序的人，我从M $源代码中提取了一些内容。

   private static string UrlTokenEncode(byte[] input)
    {
        if (input == null)
            throw new ArgumentNullException("input");
        if (input.Length < 1)
            return String.Empty;
        char[] base64Chars = null;

        ////////////////////////////////////////////////////////
        // Step 1: Do a Base64 encoding
        string base64Str = Convert.ToBase64String(input);
        if (base64Str == null)
            return null;

        int endPos;
        ////////////////////////////////////////////////////////
        // Step 2: Find how many padding chars are present in the end
        for (endPos = base64Str.Length; endPos > 0; endPos--)
        {
            if (base64Str[endPos - 1] != '=') // Found a non-padding char!
            {
                break; // Stop here
            }
        }

        ////////////////////////////////////////////////////////
        // Step 3: Create char array to store all non-padding chars,
        //      plus a char to indicate how many padding chars are needed
        base64Chars = new char[endPos + 1];
        base64Chars[endPos] = (char)((int)'0' + base64Str.Length - endPos); // Store a char at the end, to indicate how many padding chars are needed

        ////////////////////////////////////////////////////////
        // Step 3: Copy in the other chars. Transform the "+" to "-", and "/" to "_"
        for (int iter = 0; iter < endPos; iter++)
        {
            char c = base64Str[iter];

            switch (c)
            {
                case '+':
                    base64Chars[iter] = '-';
                    break;

                case '/':
                    base64Chars[iter] = '_';
                    break;

                case '=':
                    Debug.Assert(false);
                    base64Chars[iter] = c;
                    break;

                default:
                    base64Chars[iter] = c;
                    break;
            }
        }
        return new string(base64Chars);
    }

    private static byte[] UrlTokenDecode(string input)
    {
        if (input == null)
            throw new ArgumentNullException("input");

        int len = input.Length;
        if (len < 1)
            return new byte[0];

        ///////////////////////////////////////////////////////////////////
        // Step 1: Calculate the number of padding chars to append to this string.
        //         The number of padding chars to append is stored in the last char of the string.
        int numPadChars = (int)input[len - 1] - (int)'0';
        if (numPadChars < 0 || numPadChars > 10)
            return null;


        ///////////////////////////////////////////////////////////////////
        // Step 2: Create array to store the chars (not including the last char)
        //          and the padding chars
        char[] base64Chars = new char[len - 1 + numPadChars];


        ////////////////////////////////////////////////////////
        // Step 3: Copy in the chars. Transform the "-" to "+", and "*" to "/"
        for (int iter = 0; iter < len - 1; iter++)
        {
            char c = input[iter];

            switch (c)
            {
                case '-':
                    base64Chars[iter] = '+';
                    break;

                case '_':
                    base64Chars[iter] = '/';
                    break;

                default:
                    base64Chars[iter] = c;
                    break;
            }
        }

        ////////////////////////////////////////////////////////
        // Step 4: Add padding chars
        for (int iter = len - 1; iter < base64Chars.Length; iter++)
        {
            base64Chars[iter] = '=';
        }

        // Do the actual conversion
        return Convert.FromBase64CharArray(base64Chars, 0, base64Chars.Length);
    }

Answer 2

我的 KISS 解决方案适用于netstandard1.6：

public static class Utils
{
    private static readonly Regex InvalidBase64UrlTokens = new Regex(
        @"[^=a-z0-9]", 
        RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.CultureInvariant);

    public static string Base64UrlTokenEncode(byte[] data)
    {
        var padding = 0;
        var base64String = Convert.ToBase64String(data);
        return InvalidBase64UrlTokens.Replace(base64String, m => {
            switch (m.Value)
            {
                case "+": return "-";
                case "=":
                    padding++;
                    return "";
                default: return "_";
            }
        }) + padding;
    }
}

通过以下 nunit 测试：

[TestFixture]
public class Base64UrlTokenEncodingTests
{        
    private static IEnumerable<TestCaseData> CompareAgainstSystemWebImplementationCases()
    {
        var random = new Random(42);
        for (var i = 0; i < 100; i++)
        {
            var bytes = new byte[i + 1];
            random.NextBytes(bytes);

            var name = Convert.ToBase64String(bytes);
            var systemWeb = System.Web.HttpServerUtility.UrlTokenEncode(bytes);
            yield return new TestCaseData(bytes).SetName(name).Returns(systemWeb);
        }
    }

    [TestCaseSource(nameof(CompareAgainstSystemWebImplementationCases))]
    public string CompareAgainstSystemWebImplementation(byte[] data) =>
        Utils.Base64UrlTokenEncode(data);
}