c# - 为什么图像开头有不需要的额外字节？

问题:

我为我弟弟做了一个主页，可以在这里访问:
http://www.daniel-steiger.ch

它在 Linux 上使用 Microsoft ASP.NET MVC3 和 mono 3，通过 fastcgi 和 nginx(加上我自己的 DNS 服务器)。

现在我知道这是一个不寻常的星座，但到目前为止，一切正常。
但是，我遇到了一个非常微妙的小错误。

当在图库中单击缩略图时，我想通过图库 Controller 的 FullImage 方法在新选项卡中显示全尺寸图像。
比如这个直接url:
http://www.daniel-steiger.ch/gallery/FullImage/001.jpg

在 Internet Explorer 中，我得到的图像是文本。
在所有其他浏览器中显示“无效图像”消息。
我通过直接文件 URL 调用图像解决了这个问题，效果很好:
http://www.daniel-steiger.ch/Content/images/gallery/001.jpg?LastWriteTimeUTC=1358694795000

随后，我将这个错误报告给了单声道邮件列表
http://mono.1490590.n4.nabble.com/Bug-in-mono-3-0-1-MVC3-File-FileResult-td4658382.html

现在我得到的回应是，这都是我的错，因为我设置了错误的图像 mime 类型，这是真的。
然而，我发现奇怪的是，如果是这种情况，相同的代码在 Windows 上运行良好，而且像 Chrome 这样的智能浏览器通常会检测到错误的 mime 设置并使用正确的设置。

所以我将 mime-type 从“image/jpg”更改为“image/jpeg”，并将项目重新部署到服务器。
如果图像实际上是 jpeg 图像，我还检查了文件实用程序，确实是。

奇怪的是，它仍然没有显示图像。
在 Internet Explorer 上，我现在得到“不可用”。
在所有其他浏览器上，我得到:图像无法显示，因为它包含错误。

我现在从图像包含错误的 URL 中获取图像。
wget http://www.daniel-steiger.ch/gallery/fullimage/001.jpg

然后我对无效文件和原始文件进行了二进制比较:

cmp -l 001.jpg 001a.jpg   | awk '{printf "%08X %02X %02X\n", $1, strtonum(0$2), strtonum(0$3)}' >> comparison.txt

这是比较结果:

BinDiff 让我眼前一亮的是，Internet Explorer 说他找不到的图像实际上有 1.7 MB 大小，并且包含额外的字节:

31 39 36 62 36 38 0D 0A

一开始...
任何人都知道这里出了什么问题/这些字节可能来自哪里(除了它最有可能来自 mono/fastcgi 中的错误这一事实之外)？

顺便说一句，这是新的 Controller 代码:

namespace Homepage.Controllers
{


    public class GalleryController : Controller
    {


        protected static string GetImageDirectory()
        {
            string bd = AppDomain.CurrentDomain.BaseDirectory;
            string strImageDirectory = System.IO.Path.Combine(bd,
            "Content");
            strImageDirectory =
            System.IO.Path.Combine(strImageDirectory, "images");
            strImageDirectory =
            System.IO.Path.Combine(strImageDirectory, "gallery");

            return strImageDirectory;
        } // End Function GetImageDirectory


        protected static string strImageDirectory = GetImageDirectory();


        public FileResult FullImage(string id)
        {
            string strFileName =
            System.IO.Path.Combine(strImageDirectory, id);

            //return new FilePathResult("CorrectFullPathAndFileName", "CorrectMime");
            //return File(strFileName, "image/jpg"); // Old
            return File(strFileName, "image/jpeg"); // New
        } // End Action FullImage



        public FileResult Thumb(string id)
        {
            //return Redirect(id);

            string strFileName =
            System.IO.Path.Combine(strImageDirectory, id);

            System.IO.Stream ms =
            Tools.Imaging.GetThumbnailStream(strFileName,
            System.Drawing.Imaging.ImageFormat.Png);
            return File(ms, "image/png");
            /*
            using (System.IO.Stream ms =
            Tools.Imaging.GetThumbnailStream(strFileName,
            System.Drawing.Imaging.ImageFormat.Png))
            {
                return File(ms, "image/png");
            }*/
        } // End Action Thumb


    } // End Class GalleryController : Controller


} // End Namespace Homepage.Controllers

编辑:
它变得陌生:
还有一个带有

的额外序列

0d 0a 0d 0a 30 0d 0a 0d  0a

最后...

我刚刚做了 hexdump，发现原始文件有 filesize(屏住呼吸):

00196b68

这里是十六进制转储(每个 8 MB):

规范格式(hexdump -C 001.jpg > 001.txt):
原始文件:http://www.daniel-steiger.ch/001.txt
拙劣的文件:http://www.daniel-steiger.ch/001a.txt

纯转储 (hexdump 001.jpg > 001_1.txt):
原始文件:http://www.daniel-steiger.ch/001_1.txt
拙劣的文件:http://www.daniel-steiger.ch/001a_1.txt

嗯，恶意文件的十六进制转储是 5 MB，原始文件是 8.2 MB...

我用的是最新稳定的nginx:

sudo -s
nginx=stable # use nginx=development for latest development version
add-apt-repository ppa:nginx/$nginx
apt-get update 
apt-get install nginx

Tools.Imaging 的完整代码(同时将 Tools 重命名为 MvcTools，以匹配程序集命名空间)

using System;
using System.Text;


namespace MvcTools
{


    public class Imaging
    {

        //public static System.Drawing.Size m_sMaxThumbNailDimensions = new System.Drawing.Size(200, 200);
        public static System.Drawing.Size m_sMaxThumbNailDimensions = new System.Drawing.Size(300, 300);

        public static System.IO.Stream GetImageAsStream(
                                                 string strOrgFileName
                                                , System.Drawing.Imaging.ImageFormat ifOutputFormat
                                           )
        {
            return GetImageAsStream(strOrgFileName, ifOutputFormat, 1024);
        } // End Function GetImage


        public static System.IO.Stream GetImageAsStream(
                                                 string strOrgFileName
                                                ,System.Drawing.Imaging.ImageFormat ifOutputFormat
                                                ,int rez
                                           )
        {
            System.IO.MemoryStream ms = null;

            if (!System.IO.File.Exists(strOrgFileName))
                throw new System.IO.FileNotFoundException(strOrgFileName);

            try
            {

                using (System.Drawing.Image imgSourceImage = System.Drawing.Image.FromFile(strOrgFileName))
                {

                    ms = new System.IO.MemoryStream();
                    imgSourceImage.Save(ms, ifOutputFormat);
                    ms.Position = 0;
                } // End Using imgSourceImage

            } // End Try
            catch (Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.GetType().ToString());
                System.Windows.Forms.MessageBox.Show(ex.Message);
                //Response.Write(ex.Message);
            } // End Catch

            return ms;
        } // End Function GetImageAsStream


        public static System.Drawing.Size GetThumbnailSize(string strOrgFileName)
        {
            System.Drawing.Size sThumbNailSizeToUse = new System.Drawing.Size();

            try
            {

                using (System.Drawing.Image imgSourceImage = System.Drawing.Image.FromFile(strOrgFileName))
                {
                    decimal decPixToSubstract = 0;
                    decimal decPercentage;

                    if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)
                    {
                        if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)
                        {
                            decPercentage = (((decimal)imgSourceImage.Size.Width - (decimal)m_sMaxThumbNailDimensions.Width) / (decimal)imgSourceImage.Size.Width);
                            decPixToSubstract = decPercentage * imgSourceImage.Size.Height;
                            sThumbNailSizeToUse.Width = m_sMaxThumbNailDimensions.Width;
                            sThumbNailSizeToUse.Height = imgSourceImage.Size.Height - (int)decPixToSubstract;
                        } // End if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)
                        else
                        {
                            decPercentage = (((decimal)imgSourceImage.Size.Height - (decimal)m_sMaxThumbNailDimensions.Height) / (decimal)imgSourceImage.Size.Height);
                            decPixToSubstract = decPercentage * (decimal)imgSourceImage.Size.Width;
                            sThumbNailSizeToUse.Height = m_sMaxThumbNailDimensions.Height;
                            sThumbNailSizeToUse.Width = imgSourceImage.Size.Width - (int)decPixToSubstract;
                        } // End else of if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)

                    } // End if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)
                    else
                    {
                        sThumbNailSizeToUse.Width = imgSourceImage.Size.Width;
                        sThumbNailSizeToUse.Height = imgSourceImage.Size.Height;
                    } // End else of if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)

                } // End Using imgSourceImage

            } // End Try
            catch (Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
                //Response.Write(ex.Message);
            } // End Catch

            return sThumbNailSizeToUse;
        } // End Sub GetThumbnailSize(string strOrgFileName)


        // http://stackoverflow.com/questions/7319842/mvc3-razor-thumbnail-resize-image-ideas
        // http://stackoverflow.com/questions/1528525/alternatives-to-system-drawing-for-use-with-asp-net/1528908#1528908
        public static void GenerateThumbnailFile(
                                        string strPhysicalPath,
                                        string strOrgFileName, string strThumbnailFileName,
                                        System.Drawing.Imaging.ImageFormat ifOutputFormat, int rez
                                     )
        {

            try
            {

                using (System.Drawing.Image imgSourceImage = System.Drawing.Image.FromFile(strOrgFileName))
                {
                    //System.Drawing.Image oImg = System.Drawing.Image.FromStream(fil.InputStream);

                    decimal decPixToSubstract = 0;
                    decimal decPercentage;

                    //default
                    System.Drawing.Size sThumbNailSizeToUse = new System.Drawing.Size();
                    if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)
                    {
                        if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)
                        {
                            decPercentage = (((decimal)imgSourceImage.Size.Width - (decimal)m_sMaxThumbNailDimensions.Width) / (decimal)imgSourceImage.Size.Width);
                            decPixToSubstract = decPercentage * imgSourceImage.Size.Height;
                            sThumbNailSizeToUse.Width = m_sMaxThumbNailDimensions.Width;
                            sThumbNailSizeToUse.Height = imgSourceImage.Size.Height - (int)decPixToSubstract;
                        } // End if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)
                        else
                        {
                            decPercentage = (((decimal)imgSourceImage.Size.Height - (decimal)m_sMaxThumbNailDimensions.Height) / (decimal)imgSourceImage.Size.Height);
                            decPixToSubstract = decPercentage * (decimal)imgSourceImage.Size.Width;
                            sThumbNailSizeToUse.Height = m_sMaxThumbNailDimensions.Height;
                            sThumbNailSizeToUse.Width = imgSourceImage.Size.Width - (int)decPixToSubstract;
                        } // End else of if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)

                    } // End if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)
                    else
                    {
                        sThumbNailSizeToUse.Width = imgSourceImage.Size.Width;
                        sThumbNailSizeToUse.Height = imgSourceImage.Size.Height;
                    } // End else of if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)

                    using (System.Drawing.Bitmap bmpThumbnail = new System.Drawing.Bitmap(sThumbNailSizeToUse.Width, sThumbNailSizeToUse.Height))
                    {
                        bmpThumbnail.SetResolution(rez, rez);
                        using (System.Drawing.Image imgThumbNail = bmpThumbnail)
                        {

                            using (System.Drawing.Graphics gGraphicsContext = System.Drawing.Graphics.FromImage(imgThumbNail))
                            {
                                gGraphicsContext.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                                gGraphicsContext.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                                gGraphicsContext.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

                                System.Drawing.Rectangle rThumbnailDimension = new System.Drawing.Rectangle(0, 0, sThumbNailSizeToUse.Width, sThumbNailSizeToUse.Height);
                                gGraphicsContext.DrawImage(imgSourceImage, rThumbnailDimension);
                            } // End Using gGraphicsContext

                            imgThumbNail.Save(System.IO.Path.Combine(strPhysicalPath, strThumbnailFileName), ifOutputFormat);
                        } // End Using imgThumbNail

                    } // End Using bmpThumbnail

                } // End Using imgSourceImage

            } // End Try
            catch (Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
                //Response.Write(ex.Message);
            } // End Catch

        } // End Function GenerateThumbNail


        public static System.IO.Stream GetThumbnailStream(
                                                               string strOrgFileName
                                                             , System.Drawing.Imaging.ImageFormat ifOutputFormat
                                                         )
        {
            return GetThumbnailStream(strOrgFileName, ifOutputFormat, 1024);
        } // End Function GetThumbnailStream


        public static System.IO.Stream GetThumbnailStream(
                                      string strOrgFileName
                                     ,System.Drawing.Imaging.ImageFormat ifOutputFormat
                                     ,int rez
                                  )
        {

            System.IO.MemoryStream ms = null;

            try
            {

                using (System.Drawing.Image imgSourceImage = System.Drawing.Image.FromFile(strOrgFileName))
                {
                    decimal decPixToSubstract = 0;
                    decimal decPercentage;

                    System.Drawing.Size sThumbNailSizeToUse = new System.Drawing.Size();
                    if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)
                    {
                        if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)
                        {
                            decPercentage = (((decimal)imgSourceImage.Size.Width - (decimal)m_sMaxThumbNailDimensions.Width) / (decimal)imgSourceImage.Size.Width);
                            decPixToSubstract = decPercentage * imgSourceImage.Size.Height;
                            sThumbNailSizeToUse.Width = m_sMaxThumbNailDimensions.Width;
                            sThumbNailSizeToUse.Height = imgSourceImage.Size.Height - (int)decPixToSubstract;
                        } // End if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)
                        else
                        {
                            decPercentage = (((decimal)imgSourceImage.Size.Height - (decimal)m_sMaxThumbNailDimensions.Height) / (decimal)imgSourceImage.Size.Height);
                            decPixToSubstract = decPercentage * (decimal)imgSourceImage.Size.Width;
                            sThumbNailSizeToUse.Height = m_sMaxThumbNailDimensions.Height;
                            sThumbNailSizeToUse.Width = imgSourceImage.Size.Width - (int)decPixToSubstract;
                        } // End else of if (imgSourceImage.Size.Width > imgSourceImage.Size.Height)

                    } // End if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)
                    else
                    {
                        sThumbNailSizeToUse.Width = imgSourceImage.Size.Width;
                        sThumbNailSizeToUse.Height = imgSourceImage.Size.Height;
                    } // End else of if (m_sMaxThumbNailDimensions.Width < imgSourceImage.Size.Width || m_sMaxThumbNailDimensions.Height < imgSourceImage.Size.Height)


                    using (System.Drawing.Bitmap bmpThumbnail = new System.Drawing.Bitmap(sThumbNailSizeToUse.Width, sThumbNailSizeToUse.Height))
                    {
                        bmpThumbnail.SetResolution(rez, rez);
                        using (System.Drawing.Image imgThumbNail = bmpThumbnail)
                        {

                            using (System.Drawing.Graphics gGraphicsContext = System.Drawing.Graphics.FromImage(imgThumbNail))
                            {
                                gGraphicsContext.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                                gGraphicsContext.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                                gGraphicsContext.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

                                System.Drawing.Rectangle rThumbnailDimension = new System.Drawing.Rectangle(0, 0, sThumbNailSizeToUse.Width, sThumbNailSizeToUse.Height);
                                gGraphicsContext.DrawImage(imgSourceImage, rThumbnailDimension);

                                ms = new System.IO.MemoryStream();
                                imgThumbNail.Save(ms, ifOutputFormat);
                                ms.Position = 0;
                            } // End Using gGraphicsContext

                        } // End Using imgThumbNail

                    } // End Using bmpThumbnail


                    /*
                    byte[] buffer = null;
                    using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
                    {
                        imgThumbNail.Save(ms, ifOutputFormat);
                        buffer = ms.ToArray();
                    }
                    */

                    // Exerts from Page_Load method 
                    //Response.ContentType = "image/" + extension;
                    //Response.OutputStream.Write(pBuffer, 0, pBuffer.Length);
                    //Response.End();

                    //imgThumbNail.Save(System.IO.Path.Combine(strPhysicalPath, strThumbnailFileName), ifOutputFormat);
                } // End Using imgSourceImage

            } // End Try
            catch (Exception ex)
            {
                //Console.WriteLine(ex.Message);
                System.Windows.Forms.MessageBox.Show(ex.Message);
                //Response.Write(ex.Message);
            } // End Catch

            //System.Windows.Forms.MessageBox.Show("image/" + ifOutputFormat.ToString().ToLower());
            return ms;
        } // End Function GenerateThumbNail


    } // End Class Imaging


} // End Namespace Tools

最佳答案

这似乎是一个涉及 Chuncked transfer encoding 的错误在

Class: System.Web.HttpResponse (or one of its dependencies)
Method: TransmitFile(string filename)

编辑:
构造函数中有这段代码:

if (worker_request != null)
      use_chunked = (worker_request.GetHttpVersion () == "HTTP/1.1");

修补它以检查 CGI(如果是 CGI，服务器会处理文件传输，因此可能没有根据 RFC 3875 从 FastCGI 服务器返回的分块编码。

        internal HttpResponse (HttpWorkerRequest worker_request, HttpContext context) : this ()
        {
            WorkerRequest = worker_request;
            this.context = context;

#if !TARGET_J2EE
            if (worker_request != null)
            {

                if(worker_request.GetHttpVersion () == "HTTP/1.1")
                {
                    string GatewayIface = context.Request.ServerVariables["GATEWAY_INTERFACE"];
                    use_chunked = (GatewayIface == null || !GatewayIface.StartsWith("CGI"));
                }
                else
                    use_chunked = false;

            }
#endif
            writer = new HttpWriter (this);
        }

添加补丁到 https://bugzilla.xamarin.com/show_bug.cgi?id=10001
在 mono 3.2.3 中修复了

关于c# - 为什么图像开头有不需要的额外字节？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14662795/

c# - 为什么图像开头有不需要的额外字节？

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