Base64 字符串抛出无效字符错误

发布于 2024-07-15 19:08:44 字数 698 浏览 6 评论 0原文

我不断收到 Base64 无效字符错误，尽管我不应该这样做。

该程序获取 XML 文件并将其导出到文档中。如果用户愿意，它也会压缩文件。压缩工作正常并返回一个 Base64 字符串，该字符串被编码为 UTF-8 并写入文件。

当将文档重新加载到程序中时，我必须检查它是否被压缩，代码很简单：

byte[] gzBuffer = System.Convert.FromBase64String(text);
return "1F-8B-08" == BitConverter.ToString(new List<Byte>(gzBuffer).GetRange(4, 3).ToArray());

它检查字符串的开头以查看其中是否有 GZips 代码。

现在的问题是，我所有的测试都有效。我获取一个字符串，对其进行压缩、解压缩，然后将其与原始字符串进行比较。问题是当我获取从 ADO 记录集返回的字符串时。该字符串正是写入文件的内容（在末尾添加了“\0”，但我认为甚至没有做任何事情，即使修剪掉它仍然会抛出）。我什至将整个字符串复制并粘贴到测试方法中，然后对其进行压缩/解压缩。工作正常。

测试将通过，但使用完全相同的字符串代码将失败？唯一的区别是，我不是仅仅声明一个常规字符串并将其传递进去，而是从记录集中返回一个字符串。

关于我做错了什么有什么想法吗？

原文

I keep getting a Base64 invalid character error even though I shouldn't.

The program takes an XML file and exports it to a document. If the user wants, it will compress the file as well. The compression works fine and returns a Base64 String which is encoded into UTF-8 and written to a file.

When its time to reload the document into the program I have to check whether its compressed or not, the code is simply:

byte[] gzBuffer = System.Convert.FromBase64String(text);
return "1F-8B-08" == BitConverter.ToString(new List<Byte>(gzBuffer).GetRange(4, 3).ToArray());

It checks the beginning of the string to see if it has GZips code in it.

Now the thing is, all my tests work. I take a string, compress it, decompress it, and compare it to the original. The problem is when I get the string returned from an ADO Recordset. The string is exactly what was written to the file (with the addition of a "\0" at the end, but I don't think that even does anything, even trimmed off it still throws). I even copy and pasted the entire string into a test method and compress/decompress that. Works fine.

The tests will pass but the code will fail using the exact same string? The only difference is instead of just declaring a regular string and passing it in I'm getting one returned from a recordset.

Any ideas on what am I doing wrong?

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做个ˇ局外人 2024-07-22 19:08:45

string stringToDecrypt = HttpContext.Current.Request.QueryString.ToString()

//改成
字符串 stringToDecrypt = HttpUtility.UrlDecode(HttpContext.Current.Request.QueryString.ToString())

string stringToDecrypt = HttpContext.Current.Request.QueryString.ToString()

//change to
string stringToDecrypt = HttpUtility.UrlDecode(HttpContext.Current.Request.QueryString.ToString())

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最丧也最甜 2024-07-22 19:08:45

如果无法从字符串末尾删除 \0，您可以为编码的每个字符串添加您自己的字符，并在解码时将其删除。

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方圜几里 2024-07-22 19:08:45

从字符串转换 Base64 的一个问题是，某些转换函数使用前面的“data:image/jpg;base64”，而其他转换函数仅接受实际数据。

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情释 2024-07-22 19:08:44

你说

该字符串与所写入的内容完全相同
到文件（添加
末尾有“\0”，但我不认为
甚至可以做任何事情）。

事实上，它确实做了一些事情（它导致您的代码抛出 FormatException:"Base-64 字符串中的无效字符"），因为 Convert.FromBase64String 不认为“\0”是有效的 Base64 字符。

  byte[] data1 = Convert.FromBase64String("AAAA\0"); // Throws exception
  byte[] data2 = Convert.FromBase64String("AAAA");   // Works

解决方案：去掉零终止符。（也许调用.Trim("\0")）

注释：

Convert.FromBase64String 的 MSDN 文档说它会抛出 FormatException 时

s 的长度，忽略空格
字符，不是零或倍数
共 4 个。
-或-
s 的格式无效。 s 包含非基 64 字符，更多
超过两个填充字符，或
其中的非空白字符
填充字符。

然后

按升序排列的 64 位基数
从零开始是大写字符
“A”到“Z”，小写字符“a”
到“z”，数字“0”到“9”，以及
符号“+”和“/”。

You say

The string is exactly what was written
to the file (with the addition of a
"\0" at the end, but I don't think
that even does anything).

In fact, it does do something (it causes your code to throw a FormatException:"Invalid character in a Base-64 string") because the Convert.FromBase64String does not consider "\0" to be a valid Base64 character.

  byte[] data1 = Convert.FromBase64String("AAAA\0"); // Throws exception
  byte[] data2 = Convert.FromBase64String("AAAA");   // Works

Solution: Get rid of the zero termination. (Maybe call .Trim("\0"))

Notes:

The MSDN docs for Convert.FromBase64String say it will throw a FormatException when

The length of s, ignoring white space
characters, is not zero or a multiple
of 4.
-or-
The format of s is invalid. s contains a non-base 64 character, more
than two padding characters, or a
non-white space character among the
padding characters.

and that

The base 64 digits in ascending order
from zero are the uppercase characters
'A' to 'Z', lowercase characters 'a'
to 'z', numerals '0' to '9', and the
symbols '+' and '/'.

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