ContentType

string extension;
extension = extension.ToUpper();
string contentType;

if(extension == "*")
 contentType = "application/octet-stream";
else if(extension == "323")
 contentType = "text/h323";
else if(extension == "ACX")
 contentType = "application/internet-property-stream";
else if(extension == "AI")
 contentType = "application/postscript";
else if(extension == "AIF")
 contentType = "audio/x-aiff";
else if(extension == "AIFC")
 contentType = "audio/x-aiff";
else if(extension == "AIFF")
 contentType = "audio/x-aiff";
else if(extension == "ASF")
 contentType = "video/x-ms-asf";
else if(extension == "SR")
 contentType = "video/x-ms-asf";
else if(extension == "SX")
 contentType = "video/x-ms-asf";
else if(extension == "AU")
 contentType = "audio/basic";
else if(extension == "AVI")
 contentType = "video/x-msvideo";
else if(extension == "AXS")
 contentType = "application/olescript";
else if(extension == "BAS")
 contentType = "text/plain";
else if(extension == "BCPIO")
 contentType = "application/x-bcpio";
else if(extension == "BIN")
 contentType = "application/octet-stream";
else if(extension == "BMP")
 contentType = "image/bmp";
else if(extension == "C")
 contentType = "text/plain";
else if(extension == "CAT")
 contentType = "application/vnd.ms-pkiseccat";
else if(extension == "CDF")
 contentType = "application/x-cdf";
else if(extension == "CER")
 contentType = "application/x-x509-ca-cert";
else if(extension == "CLASS")
 contentType = "application/octet-stream";
else if(extension == "CLP")
 contentType = "application/x-msclip";
else if(extension == "CMX")
 contentType = "image/x-cmx";
else if(extension == "COD")
 contentType = "image/cis-cod";
else if(extension == "CPIO")
 contentType = "application/x-cpio";
else if(extension == "CRD")
 contentType = "application/x-mscardfile";
else if(extension == "CRL")
 contentType = "application/pkix-crl";
else if(extension == "CRT")
 contentType = "application/x-x509-ca-cert";
else if(extension == "CSH")
 contentType = "application/x-csh";
else if(extension == "CSS")
 contentType = "text/css";
else if(extension == "DCR")
 contentType = "application/x-director";
else if(extension == "DER")
 contentType = "application/x-x509-ca-cert";
else if(extension == "DIR")
 contentType = "application/x-director";
else if(extension == "DLL")
 contentType = "application/x-msdownload";
else if(extension == "DMS")
 contentType = "application/octet-stream";
else if(extension == "DOC")
 contentType = "application/msword";
else if(extension == "DOT")
 contentType = "application/msword";
else if(extension == "DVI")
 contentType = "application/x-dvi";
else if(extension == "DXR")
 contentType = "application/x-director";
else if(extension == "EPS")
 contentType = "application/postscript";
else if(extension == "ETX")
 contentType = "text/x-setext";
else if(extension == "EVY")
 contentType = "application/envoy";
else if(extension == "EXE")
 contentType = "application/octet-stream";
else if(extension == "FIF")
 contentType = "application/fractals";
else if(extension == "FLR")
 contentType = "x-world/x-vrml";
else if(extension == "GIF")
 contentType = "image/gif";
else if(extension == "GTAR")
 contentType = "application/x-gtar";
else if(extension == "GZ")
 contentType = "application/x-gzip";
else if(extension == "H")
 contentType = "text/plain";
else if(extension == "HDF")
 contentType = "application/x-hdf";
else if(extension == "HLP")
 contentType = "application/winhlp";
else if(extension == "HQX")
 contentType = "application/mac-binhex40";
else if(extension == "HTA")
 contentType = "application/hta";
else if(extension == "HTC")
 contentType = "text/x-component";
else if(extension == "HTM")
 contentType = "text/html";
else if(extension == "HTML")
 contentType = "text/html";
else if(extension == "HTT")
 contentType = "text/webviewhtml";
else if(extension == "ICO")
 contentType = "image/x-icon";
else if(extension == "IEF")
 contentType = "image/ief";
else if(extension == "III")
 contentType = "application/x-iphone";
else if(extension == "INS")
 contentType = "application/x-internet-signup";
else if(extension == "ISP")
 contentType = "application/x-internet-signup";
else if(extension == "JFIF")
 contentType = "image/pipeg";
else if(extension == "JPE")
 contentType = "image/jpeg";
else if(extension == "JPEG")
 contentType = "image/jpeg";
else if(extension == "ZIP")
 contentType = "application/x-zip-compressed";
else if(extension == "RAR")
 contentType = "application/octet-stream";