Determine the file type using C#
Solution 1:
I've just converted my VB.NET class to C# to detect mime types. They will be identified by a mix of sniffing the first 256 Bytes of a file(urlmon.dll - f.e. used by internet explorer) and a set of known types.
You can also use it to check if the file is what it pretends to be(if the extension matches the type).
// check whether or not the uploaded file is an image:
var contentType = MimeTypes.GetContentType(FileUpload1.PostedFile.FileName);
if(contentType.StartsWith("image"))
{
// do something with the image ...
}
Here's the class:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.IO;
public class MimeTypes
{
private static List<string> knownTypes;
private static Dictionary<string, string> mimeTypes;
[DllImport("urlmon.dll", CharSet = CharSet.Auto)]
private static extern UInt32 FindMimeFromData(
UInt32 pBC, [MarshalAs(UnmanagedType.LPStr)]
string pwzUrl, [MarshalAs(UnmanagedType.LPArray)]
byte[] pBuffer, UInt32 cbSize, [MarshalAs(UnmanagedType.LPStr)]
string pwzMimeProposed, UInt32 dwMimeFlags, ref UInt32 ppwzMimeOut, UInt32 dwReserverd
);
public static string GetContentType(string fileName)
{
if (knownTypes == null || mimeTypes == null)
InitializeMimeTypeLists();
string contentType = "";
string extension = System.IO.Path.GetExtension(fileName).Replace(".", "").ToLower();
mimeTypes.TryGetValue(extension, out contentType);
if (string.IsNullOrEmpty(contentType) || knownTypes.Contains(contentType))
{
string headerType = ScanFileForMimeType(fileName);
if (headerType != "application/octet-stream" || string.IsNullOrEmpty(contentType))
contentType = headerType;
}
return contentType;
}
private static string ScanFileForMimeType(string fileName)
{
try
{
byte[] buffer = new byte[256];
using (FileStream fs = new FileStream(fileName, FileMode.Open))
{
int readLength = Convert.ToInt32(Math.Min(256, fs.Length));
fs.Read(buffer, 0, readLength);
}
UInt32 mimeType = default(UInt32);
FindMimeFromData(0, null, buffer, 256, null, 0, ref mimeType, 0);
IntPtr mimeTypePtr = new IntPtr(mimeType);
string mime = Marshal.PtrToStringUni(mimeTypePtr);
Marshal.FreeCoTaskMem(mimeTypePtr);
if (string.IsNullOrEmpty(mime))
mime = "application/octet-stream";
return mime;
} catch (Exception ex)
{
return "application/octet-stream";
}
}
private static void InitializeMimeTypeLists()
{
knownTypes = new string[] {
"text/plain",
"text/html",
"text/xml",
"text/richtext",
"text/scriptlet",
"audio/x-aiff",
"audio/basic",
"audio/mid",
"audio/wav",
"image/gif",
"image/jpeg",
"image/pjpeg",
"image/png",
"image/x-png",
"image/tiff",
"image/bmp",
"image/x-xbitmap",
"image/x-jg",
"image/x-emf",
"image/x-wmf",
"video/avi",
"video/mpeg",
"application/octet-stream",
"application/postscript",
"application/base64",
"application/macbinhex40",
"application/pdf",
"application/xml",
"application/atom+xml",
"application/rss+xml",
"application/x-compressed",
"application/x-zip-compressed",
"application/x-gzip-compressed",
"application/java",
"application/x-msdownload"
}.ToList();
mimeTypes = new Dictionary<string, string>();
mimeTypes.Add("3dm", "x-world/x-3dmf");
mimeTypes.Add("3dmf", "x-world/x-3dmf");
mimeTypes.Add("a", "application/octet-stream");
mimeTypes.Add("aab", "application/x-authorware-bin");
mimeTypes.Add("aam", "application/x-authorware-map");
mimeTypes.Add("aas", "application/x-authorware-seg");
mimeTypes.Add("abc", "text/vnd.abc");
mimeTypes.Add("acgi", "text/html");
mimeTypes.Add("afl", "video/animaflex");
mimeTypes.Add("ai", "application/postscript");
mimeTypes.Add("aif", "audio/aiff");
mimeTypes.Add("aifc", "audio/aiff");
mimeTypes.Add("aiff", "audio/aiff");
mimeTypes.Add("aim", "application/x-aim");
mimeTypes.Add("aip", "text/x-audiosoft-intra");
mimeTypes.Add("ani", "application/x-navi-animation");
mimeTypes.Add("aos", "application/x-nokia-9000-communicator-add-on-software");
mimeTypes.Add("aps", "application/mime");
mimeTypes.Add("arc", "application/octet-stream");
mimeTypes.Add("arj", "application/arj");
mimeTypes.Add("art", "image/x-jg");
mimeTypes.Add("asf", "video/x-ms-asf");
mimeTypes.Add("asm", "text/x-asm");
mimeTypes.Add("asp", "text/asp");
mimeTypes.Add("asx", "application/x-mplayer2");
mimeTypes.Add("au", "audio/basic");
mimeTypes.Add("avi", "video/avi");
mimeTypes.Add("avs", "video/avs-video");
mimeTypes.Add("bcpio", "application/x-bcpio");
mimeTypes.Add("bin", "application/octet-stream");
mimeTypes.Add("bm", "image/bmp");
mimeTypes.Add("bmp", "image/bmp");
mimeTypes.Add("boo", "application/book");
mimeTypes.Add("book", "application/book");
mimeTypes.Add("boz", "application/x-bzip2");
mimeTypes.Add("bsh", "application/x-bsh");
mimeTypes.Add("bz", "application/x-bzip");
mimeTypes.Add("bz2", "application/x-bzip2");
mimeTypes.Add("c", "text/plain");
mimeTypes.Add("c++", "text/plain");
mimeTypes.Add("cat", "application/vnd.ms-pki.seccat");
mimeTypes.Add("cc", "text/plain");
mimeTypes.Add("ccad", "application/clariscad");
mimeTypes.Add("cco", "application/x-cocoa");
mimeTypes.Add("cdf", "application/cdf");
mimeTypes.Add("cer", "application/pkix-cert");
mimeTypes.Add("cha", "application/x-chat");
mimeTypes.Add("chat", "application/x-chat");
mimeTypes.Add("class", "application/java");
mimeTypes.Add("com", "application/octet-stream");
mimeTypes.Add("conf", "text/plain");
mimeTypes.Add("cpio", "application/x-cpio");
mimeTypes.Add("cpp", "text/x-c");
mimeTypes.Add("cpt", "application/x-cpt");
mimeTypes.Add("crl", "application/pkcs-crl");
mimeTypes.Add("css", "text/css");
mimeTypes.Add("def", "text/plain");
mimeTypes.Add("der", "application/x-x509-ca-cert");
mimeTypes.Add("dif", "video/x-dv");
mimeTypes.Add("dir", "application/x-director");
mimeTypes.Add("dl", "video/dl");
mimeTypes.Add("doc", "application/msword");
mimeTypes.Add("dot", "application/msword");
mimeTypes.Add("dp", "application/commonground");
mimeTypes.Add("drw", "application/drafting");
mimeTypes.Add("dump", "application/octet-stream");
mimeTypes.Add("dv", "video/x-dv");
mimeTypes.Add("dvi", "application/x-dvi");
mimeTypes.Add("dwf", "drawing/x-dwf (old)");
mimeTypes.Add("dwg", "application/acad");
mimeTypes.Add("dxf", "application/dxf");
mimeTypes.Add("eps", "application/postscript");
mimeTypes.Add("es", "application/x-esrehber");
mimeTypes.Add("etx", "text/x-setext");
mimeTypes.Add("evy", "application/envoy");
mimeTypes.Add("exe", "application/octet-stream");
mimeTypes.Add("f", "text/plain");
mimeTypes.Add("f90", "text/x-fortran");
mimeTypes.Add("fdf", "application/vnd.fdf");
mimeTypes.Add("fif", "image/fif");
mimeTypes.Add("fli", "video/fli");
mimeTypes.Add("flv", "video/x-flv");
mimeTypes.Add("for", "text/x-fortran");
mimeTypes.Add("fpx", "image/vnd.fpx");
mimeTypes.Add("g", "text/plain");
mimeTypes.Add("g3", "image/g3fax");
mimeTypes.Add("gif", "image/gif");
mimeTypes.Add("gl", "video/gl");
mimeTypes.Add("gsd", "audio/x-gsm");
mimeTypes.Add("gtar", "application/x-gtar");
mimeTypes.Add("gz", "application/x-compressed");
mimeTypes.Add("h", "text/plain");
mimeTypes.Add("help", "application/x-helpfile");
mimeTypes.Add("hgl", "application/vnd.hp-hpgl");
mimeTypes.Add("hh", "text/plain");
mimeTypes.Add("hlp", "application/x-winhelp");
mimeTypes.Add("htc", "text/x-component");
mimeTypes.Add("htm", "text/html");
mimeTypes.Add("html", "text/html");
mimeTypes.Add("htmls", "text/html");
mimeTypes.Add("htt", "text/webviewhtml");
mimeTypes.Add("htx", "text/html");
mimeTypes.Add("ice", "x-conference/x-cooltalk");
mimeTypes.Add("ico", "image/x-icon");
mimeTypes.Add("idc", "text/plain");
mimeTypes.Add("ief", "image/ief");
mimeTypes.Add("iefs", "image/ief");
mimeTypes.Add("iges", "application/iges");
mimeTypes.Add("igs", "application/iges");
mimeTypes.Add("ima", "application/x-ima");
mimeTypes.Add("imap", "application/x-httpd-imap");
mimeTypes.Add("inf", "application/inf");
mimeTypes.Add("ins", "application/x-internett-signup");
mimeTypes.Add("ip", "application/x-ip2");
mimeTypes.Add("isu", "video/x-isvideo");
mimeTypes.Add("it", "audio/it");
mimeTypes.Add("iv", "application/x-inventor");
mimeTypes.Add("ivr", "i-world/i-vrml");
mimeTypes.Add("ivy", "application/x-livescreen");
mimeTypes.Add("jam", "audio/x-jam");
mimeTypes.Add("jav", "text/plain");
mimeTypes.Add("java", "text/plain");
mimeTypes.Add("jcm", "application/x-java-commerce");
mimeTypes.Add("jfif", "image/jpeg");
mimeTypes.Add("jfif-tbnl", "image/jpeg");
mimeTypes.Add("jpe", "image/jpeg");
mimeTypes.Add("jpeg", "image/jpeg");
mimeTypes.Add("jpg", "image/jpeg");
mimeTypes.Add("jps", "image/x-jps");
mimeTypes.Add("js", "application/x-javascript");
mimeTypes.Add("jut", "image/jutvision");
mimeTypes.Add("kar", "audio/midi");
mimeTypes.Add("ksh", "application/x-ksh");
mimeTypes.Add("la", "audio/nspaudio");
mimeTypes.Add("lam", "audio/x-liveaudio");
mimeTypes.Add("latex", "application/x-latex");
mimeTypes.Add("lha", "application/lha");
mimeTypes.Add("lhx", "application/octet-stream");
mimeTypes.Add("list", "text/plain");
mimeTypes.Add("lma", "audio/nspaudio");
mimeTypes.Add("log", "text/plain");
mimeTypes.Add("lsp", "application/x-lisp");
mimeTypes.Add("lst", "text/plain");
mimeTypes.Add("lsx", "text/x-la-asf");
mimeTypes.Add("ltx", "application/x-latex");
mimeTypes.Add("lzh", "application/octet-stream");
mimeTypes.Add("lzx", "application/lzx");
mimeTypes.Add("m", "text/plain");
mimeTypes.Add("m1v", "video/mpeg");
mimeTypes.Add("m2a", "audio/mpeg");
mimeTypes.Add("m2v", "video/mpeg");
mimeTypes.Add("m3u", "audio/x-mpequrl");
mimeTypes.Add("man", "application/x-troff-man");
mimeTypes.Add("map", "application/x-navimap");
mimeTypes.Add("mar", "text/plain");
mimeTypes.Add("mbd", "application/mbedlet");
mimeTypes.Add("mc$", "application/x-magic-cap-package-1.0");
mimeTypes.Add("mcd", "application/mcad");
mimeTypes.Add("mcf", "image/vasa");
mimeTypes.Add("mcp", "application/netmc");
mimeTypes.Add("me", "application/x-troff-me");
mimeTypes.Add("mht", "message/rfc822");
mimeTypes.Add("mhtml", "message/rfc822");
mimeTypes.Add("mid", "audio/midi");
mimeTypes.Add("midi", "audio/midi");
mimeTypes.Add("mif", "application/x-frame");
mimeTypes.Add("mime", "message/rfc822");
mimeTypes.Add("mjf", "audio/x-vnd.audioexplosion.mjuicemediafile");
mimeTypes.Add("mjpg", "video/x-motion-jpeg");
mimeTypes.Add("mm", "application/base64");
mimeTypes.Add("mme", "application/base64");
mimeTypes.Add("mod", "audio/mod");
mimeTypes.Add("moov", "video/quicktime");
mimeTypes.Add("mov", "video/quicktime");
mimeTypes.Add("movie", "video/x-sgi-movie");
mimeTypes.Add("mp2", "audio/mpeg");
mimeTypes.Add("mp3", "audio/mpeg3");
mimeTypes.Add("mpa", "audio/mpeg");
mimeTypes.Add("mpc", "application/x-project");
mimeTypes.Add("mpe", "video/mpeg");
mimeTypes.Add("mpeg", "video/mpeg");
mimeTypes.Add("mpg", "video/mpeg");
mimeTypes.Add("mpga", "audio/mpeg");
mimeTypes.Add("mpp", "application/vnd.ms-project");
mimeTypes.Add("mpt", "application/x-project");
mimeTypes.Add("mpv", "application/x-project");
mimeTypes.Add("mpx", "application/x-project");
mimeTypes.Add("mrc", "application/marc");
mimeTypes.Add("ms", "application/x-troff-ms");
mimeTypes.Add("mv", "video/x-sgi-movie");
mimeTypes.Add("my", "audio/make");
mimeTypes.Add("mzz", "application/x-vnd.audioexplosion.mzz");
mimeTypes.Add("nap", "image/naplps");
mimeTypes.Add("naplps", "image/naplps");
mimeTypes.Add("nc", "application/x-netcdf");
mimeTypes.Add("ncm", "application/vnd.nokia.configuration-message");
mimeTypes.Add("nif", "image/x-niff");
mimeTypes.Add("niff", "image/x-niff");
mimeTypes.Add("nix", "application/x-mix-transfer");
mimeTypes.Add("nsc", "application/x-conference");
mimeTypes.Add("nvd", "application/x-navidoc");
mimeTypes.Add("o", "application/octet-stream");
mimeTypes.Add("oda", "application/oda");
mimeTypes.Add("omc", "application/x-omc");
mimeTypes.Add("omcd", "application/x-omcdatamaker");
mimeTypes.Add("omcr", "application/x-omcregerator");
mimeTypes.Add("p", "text/x-pascal");
mimeTypes.Add("p10", "application/pkcs10");
mimeTypes.Add("p12", "application/pkcs-12");
mimeTypes.Add("p7a", "application/x-pkcs7-signature");
mimeTypes.Add("p7c", "application/pkcs7-mime");
mimeTypes.Add("pas", "text/pascal");
mimeTypes.Add("pbm", "image/x-portable-bitmap");
mimeTypes.Add("pcl", "application/vnd.hp-pcl");
mimeTypes.Add("pct", "image/x-pict");
mimeTypes.Add("pcx", "image/x-pcx");
mimeTypes.Add("pdf", "application/pdf");
mimeTypes.Add("pfunk", "audio/make");
mimeTypes.Add("pgm", "image/x-portable-graymap");
mimeTypes.Add("pic", "image/pict");
mimeTypes.Add("pict", "image/pict");
mimeTypes.Add("pkg", "application/x-newton-compatible-pkg");
mimeTypes.Add("pko", "application/vnd.ms-pki.pko");
mimeTypes.Add("pl", "text/plain");
mimeTypes.Add("plx", "application/x-pixclscript");
mimeTypes.Add("pm", "image/x-xpixmap");
mimeTypes.Add("png", "image/png");
mimeTypes.Add("pnm", "application/x-portable-anymap");
mimeTypes.Add("pot", "application/mspowerpoint");
mimeTypes.Add("pov", "model/x-pov");
mimeTypes.Add("ppa", "application/vnd.ms-powerpoint");
mimeTypes.Add("ppm", "image/x-portable-pixmap");
mimeTypes.Add("pps", "application/mspowerpoint");
mimeTypes.Add("ppt", "application/mspowerpoint");
mimeTypes.Add("ppz", "application/mspowerpoint");
mimeTypes.Add("pre", "application/x-freelance");
mimeTypes.Add("prt", "application/pro_eng");
mimeTypes.Add("ps", "application/postscript");
mimeTypes.Add("psd", "application/octet-stream");
mimeTypes.Add("pvu", "paleovu/x-pv");
mimeTypes.Add("pwz", "application/vnd.ms-powerpoint");
mimeTypes.Add("py", "text/x-script.phyton");
mimeTypes.Add("pyc", "applicaiton/x-bytecode.python");
mimeTypes.Add("qcp", "audio/vnd.qcelp");
mimeTypes.Add("qd3", "x-world/x-3dmf");
mimeTypes.Add("qd3d", "x-world/x-3dmf");
mimeTypes.Add("qif", "image/x-quicktime");
mimeTypes.Add("qt", "video/quicktime");
mimeTypes.Add("qtc", "video/x-qtc");
mimeTypes.Add("qti", "image/x-quicktime");
mimeTypes.Add("qtif", "image/x-quicktime");
mimeTypes.Add("ra", "audio/x-pn-realaudio");
mimeTypes.Add("ram", "audio/x-pn-realaudio");
mimeTypes.Add("ras", "application/x-cmu-raster");
mimeTypes.Add("rast", "image/cmu-raster");
mimeTypes.Add("rexx", "text/x-script.rexx");
mimeTypes.Add("rf", "image/vnd.rn-realflash");
mimeTypes.Add("rgb", "image/x-rgb");
mimeTypes.Add("rm", "application/vnd.rn-realmedia");
mimeTypes.Add("rmi", "audio/mid");
mimeTypes.Add("rmm", "audio/x-pn-realaudio");
mimeTypes.Add("rmp", "audio/x-pn-realaudio");
mimeTypes.Add("rng", "application/ringing-tones");
mimeTypes.Add("rnx", "application/vnd.rn-realplayer");
mimeTypes.Add("roff", "application/x-troff");
mimeTypes.Add("rp", "image/vnd.rn-realpix");
mimeTypes.Add("rpm", "audio/x-pn-realaudio-plugin");
mimeTypes.Add("rt", "text/richtext");
mimeTypes.Add("rtf", "text/richtext");
mimeTypes.Add("rtx", "application/rtf");
mimeTypes.Add("rv", "video/vnd.rn-realvideo");
mimeTypes.Add("s", "text/x-asm");
mimeTypes.Add("s3m", "audio/s3m");
mimeTypes.Add("saveme", "application/octet-stream");
mimeTypes.Add("sbk", "application/x-tbook");
mimeTypes.Add("scm", "application/x-lotusscreencam");
mimeTypes.Add("sdml", "text/plain");
mimeTypes.Add("sdp", "application/sdp");
mimeTypes.Add("sdr", "application/sounder");
mimeTypes.Add("sea", "application/sea");
mimeTypes.Add("set", "application/set");
mimeTypes.Add("sgm", "text/sgml");
mimeTypes.Add("sgml", "text/sgml");
mimeTypes.Add("sh", "application/x-bsh");
mimeTypes.Add("shtml", "text/html");
mimeTypes.Add("sid", "audio/x-psid");
mimeTypes.Add("sit", "application/x-sit");
mimeTypes.Add("skd", "application/x-koan");
mimeTypes.Add("skm", "application/x-koan");
mimeTypes.Add("skp", "application/x-koan");
mimeTypes.Add("skt", "application/x-koan");
mimeTypes.Add("sl", "application/x-seelogo");
mimeTypes.Add("smi", "application/smil");
mimeTypes.Add("smil", "application/smil");
mimeTypes.Add("snd", "audio/basic");
mimeTypes.Add("sol", "application/solids");
mimeTypes.Add("spc", "application/x-pkcs7-certificates");
mimeTypes.Add("spl", "application/futuresplash");
mimeTypes.Add("spr", "application/x-sprite");
mimeTypes.Add("sprite", "application/x-sprite");
mimeTypes.Add("src", "application/x-wais-source");
mimeTypes.Add("ssi", "text/x-server-parsed-html");
mimeTypes.Add("ssm", "application/streamingmedia");
mimeTypes.Add("sst", "application/vnd.ms-pki.certstore");
mimeTypes.Add("step", "application/step");
mimeTypes.Add("stl", "application/sla");
mimeTypes.Add("stp", "application/step");
mimeTypes.Add("sv4cpio", "application/x-sv4cpio");
mimeTypes.Add("sv4crc", "application/x-sv4crc");
mimeTypes.Add("svf", "image/vnd.dwg");
mimeTypes.Add("svr", "application/x-world");
mimeTypes.Add("swf", "application/x-shockwave-flash");
mimeTypes.Add("t", "application/x-troff");
mimeTypes.Add("talk", "text/x-speech");
mimeTypes.Add("tar", "application/x-tar");
mimeTypes.Add("tbk", "application/toolbook");
mimeTypes.Add("tcl", "application/x-tcl");
mimeTypes.Add("tcsh", "text/x-script.tcsh");
mimeTypes.Add("tex", "application/x-tex");
mimeTypes.Add("texi", "application/x-texinfo");
mimeTypes.Add("texinfo", "application/x-texinfo");
mimeTypes.Add("text", "text/plain");
mimeTypes.Add("tgz", "application/x-compressed");
mimeTypes.Add("tif", "image/tiff");
mimeTypes.Add("tr", "application/x-troff");
mimeTypes.Add("tsi", "audio/tsp-audio");
mimeTypes.Add("tsp", "audio/tsplayer");
mimeTypes.Add("tsv", "text/tab-separated-values");
mimeTypes.Add("turbot", "image/florian");
mimeTypes.Add("txt", "text/plain");
mimeTypes.Add("uil", "text/x-uil");
mimeTypes.Add("uni", "text/uri-list");
mimeTypes.Add("unis", "text/uri-list");
mimeTypes.Add("unv", "application/i-deas");
mimeTypes.Add("uri", "text/uri-list");
mimeTypes.Add("uris", "text/uri-list");
mimeTypes.Add("ustar", "application/x-ustar");
mimeTypes.Add("uu", "application/octet-stream");
mimeTypes.Add("vcd", "application/x-cdlink");
mimeTypes.Add("vcs", "text/x-vcalendar");
mimeTypes.Add("vda", "application/vda");
mimeTypes.Add("vdo", "video/vdo");
mimeTypes.Add("vew", "application/groupwise");
mimeTypes.Add("viv", "video/vivo");
mimeTypes.Add("vivo", "video/vivo");
mimeTypes.Add("vmd", "application/vocaltec-media-desc");
mimeTypes.Add("vmf", "application/vocaltec-media-file");
mimeTypes.Add("voc", "audio/voc");
mimeTypes.Add("vos", "video/vosaic");
mimeTypes.Add("vox", "audio/voxware");
mimeTypes.Add("vqe", "audio/x-twinvq-plugin");
mimeTypes.Add("vqf", "audio/x-twinvq");
mimeTypes.Add("vql", "audio/x-twinvq-plugin");
mimeTypes.Add("vrml", "application/x-vrml");
mimeTypes.Add("vrt", "x-world/x-vrt");
mimeTypes.Add("vsd", "application/x-visio");
mimeTypes.Add("vst", "application/x-visio");
mimeTypes.Add("vsw", "application/x-visio");
mimeTypes.Add("w60", "application/wordperfect6.0");
mimeTypes.Add("w61", "application/wordperfect6.1");
mimeTypes.Add("w6w", "application/msword");
mimeTypes.Add("wav", "audio/wav");
mimeTypes.Add("wb1", "application/x-qpro");
mimeTypes.Add("wbmp", "image/vnd.wap.wbmp");
mimeTypes.Add("web", "application/vnd.xara");
mimeTypes.Add("wiz", "application/msword");
mimeTypes.Add("wk1", "application/x-123");
mimeTypes.Add("wmf", "windows/metafile");
mimeTypes.Add("wml", "text/vnd.wap.wml");
mimeTypes.Add("wmlc", "application/vnd.wap.wmlc");
mimeTypes.Add("wmls", "text/vnd.wap.wmlscript");
mimeTypes.Add("wmlsc", "application/vnd.wap.wmlscriptc");
mimeTypes.Add("word", "application/msword");
mimeTypes.Add("wp", "application/wordperfect");
mimeTypes.Add("wp5", "application/wordperfect");
mimeTypes.Add("wp6", "application/wordperfect");
mimeTypes.Add("wpd", "application/wordperfect");
mimeTypes.Add("wq1", "application/x-lotus");
mimeTypes.Add("wri", "application/mswrite");
mimeTypes.Add("wrl", "application/x-world");
mimeTypes.Add("wrz", "model/vrml");
mimeTypes.Add("wsc", "text/scriplet");
mimeTypes.Add("wsrc", "application/x-wais-source");
mimeTypes.Add("wtk", "application/x-wintalk");
mimeTypes.Add("xbm", "image/x-xbitmap");
mimeTypes.Add("xdr", "video/x-amt-demorun");
mimeTypes.Add("xgz", "xgl/drawing");
mimeTypes.Add("xif", "image/vnd.xiff");
mimeTypes.Add("xl", "application/excel");
mimeTypes.Add("xla", "application/excel");
mimeTypes.Add("xlb", "application/excel");
mimeTypes.Add("xlc", "application/excel");
mimeTypes.Add("xld", "application/excel");
mimeTypes.Add("xlk", "application/excel");
mimeTypes.Add("xll", "application/excel");
mimeTypes.Add("xlm", "application/excel");
mimeTypes.Add("xls", "application/excel");
mimeTypes.Add("xlsx", "application/excel");
mimeTypes.Add("xlt", "application/excel");
mimeTypes.Add("xlv", "application/excel");
mimeTypes.Add("xlw", "application/excel");
mimeTypes.Add("xm", "audio/xm");
mimeTypes.Add("xml", "text/xml");
mimeTypes.Add("xmz", "xgl/movie");
mimeTypes.Add("xpix", "application/x-vnd.ls-xpix");
mimeTypes.Add("xpm", "image/x-xpixmap");
mimeTypes.Add("x-png", "image/png");
mimeTypes.Add("xsr", "video/x-amt-showrun");
mimeTypes.Add("xwd", "image/x-xwd");
mimeTypes.Add("xyz", "chemical/x-pdb");
mimeTypes.Add("z", "application/x-compress");
mimeTypes.Add("zip", "application/x-compressed");
mimeTypes.Add("zoo", "application/octet-stream");
mimeTypes.Add("zsh", "text/x-script.zsh");
}
}
You have to update this list when a mime type is unknown and it is not sufficient to know that it is application/octet-stream. It might suffice to check if an extension is txt but the mime-type is binary data, because that means that this file is not what it pretends to be.
Apart from that it's really easier to use a RegularExpressionValidator.
For example (only jpg-images):
<asp:FileUpload ID="FileUpload1" runat="server" /><br />
<br />
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click"
Text="Upload File" /> <br />
<br />
<asp:Label ID="Label1" runat="server"></asp:Label>
<asp:RegularExpressionValidator
id="RegularExpressionValidator1" runat="server"
ErrorMessage="Only jpeg files are allowed!"
ValidationExpression="^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))
+(.jpg|.JPG|.jpeg|.JPEG)$"
ControlToValidate="FileUpload1"></asp:RegularExpressionValidator>
In codebehind:
if (FileUpload1.HasFile)
{
string fileExt =
System.IO.Path.GetExtension(FileUpload1.FileName);
if (fileExt == ".jpeg" || fileExt == ".jpg")
{
//do what you want with this image
}
else
{
Label1.Text = "Only .jpeg files are allowed!";
}
}
Solution 2:
There is a helper class in .NET for that, called Path. What you need is
Path.GetExtension();
It is located in the System.IO namespace.
Solution 3:
It's never a good idea to write your code like that:
string fileExt = System.IO.Path.GetExtension(FileUpload1.FileName);
if (fileExt == ".jpeg" || fileExt == ".jpg")
{
//do what you want with this image
}
The reason of that is because it will give you the extension from the filename. Lets assume that the user is smart enough to change the filename from foo.exe to foo.png and upload it. In this code sample validation will be passed and this is bad for you.
The only appropriate way to identify file type is by checking it magic bytes. According to Wikipedia this term ("magic numbers") was used for a specific set of 2-byte identifiers at the beginnings of files, but since any binary sequence can be regarded as a number, any feature of a file format which uniquely distinguishes it can be used for identification. This approach offers better guarantees that the format will be identified correctly, and can often determine more precise information about the file. Reference to original post.
Because of that I had the same problem a year ago and I created a library that can help you with that scenario. It's easy to use and with few lines of code you will be safe.
Solution 4:
you can use Myrmec to identify the file type, this library use the file byte head. this library avaliable on nuget "Myrmec",and this is the repo, myrmec also support mime type,you can try it. the code will like this :
// create a sniffer instance.
Sniffer sniffer = new Sniffer();
// populate with mata data.
sniffer.Populate(FileTypes.CommonFileTypes);
// get file head byte, may be 20 bytes enough.
byte[] fileHead = ReadFileHead();
// start match.
List<string> results = sniffer.Match(fileHead);