替代Urlmon.dll中具有更多MIME类型的FindMimeFromData方法

Question

通过Windows DLL可访问的FindMimeFromData方法Urlmon.dll能够确定存储在内存中的给定数据的MIME类型,考虑到存储此类数据的字节数组的前256个字节.

然而,在阅读了它的文档后,我在Windows Internet Explorer中引领了MIME类型检测,在那里我可以找到此方法能够识别的MIME类型.见清单.如您所见,此方法仅限于26种MIME类型.

所以我想知道是否有人能指出我有更多MIME类型的另一种方法,或者另外一种方法/类我可以包含我认为合适的MIME类型.

谢谢.

Answer 1

所以我想知道是否有人能指出我有更多MIME类型的另一种方法,或者另外一种方法/类我可以包含我认为合适的MIME类型.

我使用Winista和URLMon的混合来检测上传文件的真实格式.

下载Winista:http://www.netomatix.com/Products/DocumentManagement/MimeDetector.aspx

或者使用URLMon下载项目:https: //github.com/MeaningOfLights/MimeDetect

Winista MIME检测

假设有人使用jpg扩展名重命名exe,您仍然可以使用二进制分析确定"真实"文件格式.它不会检测swf或flv,但几乎所有其他众所周知的格式+你可以得到一个十六进制编辑器并添加它可以检测的更多文件.

文件魔术

Winista使用XML文件"mime-type.xml"检测真实的MIME类型,该文件包含有关文件类型和用于标识内容类型的签名的信息.eg:

<!--
 !   Audio primary type
 ! -->

<mime-type name="audio/basic"
           description="uLaw/AU Audio File">
    <ext>au</ext><ext>snd</ext>
    <magic offset="0" type="byte" value="2e736e64000000"/>
</mime-type>

<mime-type name="audio/midi"
           description="Musical Instrument Digital Interface MIDI-sequention Sound">
    <ext>mid</ext><ext>midi</ext><ext>kar</ext>
    <magic offset="0" value="MThd"/>
</mime-type>

<mime-type name="audio/mpeg"
           description="MPEG Audio Stream, Layer III">
    <ext>mp3</ext><ext>mp2</ext><ext>mpga</ext>
    <magic offset="0" value="ID3"/>
</mime-type>

当Winista无法检测到真正的文件格式时,我已经使用了URLMon方法:

public class urlmonMimeDetect
{
    [DllImport(@"urlmon.dll", CharSet = CharSet.Auto)]
    private extern static System.UInt32 FindMimeFromData(
        System.UInt32 pBC,
        [MarshalAs(UnmanagedType.LPStr)] System.String pwzUrl,
        [MarshalAs(UnmanagedType.LPArray)] byte[] pBuffer,
        System.UInt32 cbSize,
        [MarshalAs(UnmanagedType.LPStr)] System.String pwzMimeProposed,
        System.UInt32 dwMimeFlags,
        out System.UInt32 ppwzMimeOut,
        System.UInt32 dwReserverd
    );

public string GetMimeFromFile(string filename)
{
    if (!File.Exists(filename))
        throw new FileNotFoundException(filename + " not found");

    byte[] buffer = new byte[256];
    using (FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read))
    {
        if (fs.Length >= 256)
            fs.Read(buffer, 0, 256);
        else
            fs.Read(buffer, 0, (int)fs.Length);
    }
    try
    {
        System.UInt32 mimetype;
        FindMimeFromData(0, null, buffer, 256, null, 0, out mimetype, 0);
        System.IntPtr mimeTypePtr = new IntPtr(mimetype);
        string mime = Marshal.PtrToStringUni(mimeTypePtr);
        Marshal.FreeCoTaskMem(mimeTypePtr);
        return mime;
    }
    catch (Exception e)
    {
        return "unknown/unknown";
    }
}
}

从Winista方法内部,我回到URLMon:

   public MimeType GetMimeTypeFromFile(string filePath)
    {
        sbyte[] fileData = null;
        using (FileStream srcFile = new FileStream(filePath, FileMode.Open, FileAccess.Read))
        {
            byte[] data = new byte[srcFile.Length];
            srcFile.Read(data, 0, (Int32)srcFile.Length);
            fileData = Winista.Mime.SupportUtil.ToSByteArray(data);
        }

        MimeType oMimeType = GetMimeType(fileData);
        if (oMimeType != null) return oMimeType;

        //We haven't found the file using Magic (eg a text/plain file)
        //so instead use URLMon to try and get the files format
        Winista.MimeDetect.URLMONMimeDetect.urlmonMimeDetect urlmonMimeDetect = new Winista.MimeDetect.URLMONMimeDetect.urlmonMimeDetect();
        string urlmonMimeType = urlmonMimeDetect.GetMimeFromFile(filePath);
        if (!string.IsNullOrEmpty(urlmonMimeType))
        {
            foreach (MimeType mimeType in types)
            {
                if (mimeType.Name == urlmonMimeType)
                {
                    return mimeType;
                }
            }
        }

        return oMimeType;
    }

来自netomatix的Winista.AFAIK是一个基于2000年初开源Java项目的C#重写.请享用!

您也可以使用由Paul Zahra链接的帖子中提到的Registry方法或.Net 4.5方法,但Winista是最好的恕我直言.

更新:

对于桌面应用程序,您可能会发现WindowsAPICodePack更好用:

using Microsoft.WindowsAPICodePack.Shell;
using Microsoft.WindowsAPICodePack.Shell.PropertySystem;

private static string GetFilePropertyItemTypeTextValueFromShellFile(string filePathWithExtension)
{
   var shellFile = ShellFile.FromFilePath(filePathWithExtension);
   var prop = shellFile.Properties.GetProperty(PItemTypeTextCanonical);
   return prop.FormatForDisplay(PropertyDescriptionFormatOptions.None);
}