using System; using System.IO; using System.Text; namespace InfoPathAttachmentEncoding { /// <summary> /// Decodes a file attachment and saves it to a specified path. /// </summary> public class InfoPathAttachmentDecoder { private const int SP1Header_Size = 20; private const int FIXED_HEADER = 16; private int fileSize; private int attachmentNameLength; private string attachmentName; private byte[] decodedAttachment; /// <summary> /// Accepts the Base64 encoded string /// that is the attachment. /// </summary> public InfoPathAttachmentDecoder(string theBase64EncodedString) { byte [] theData = Convert.FromBase64String(theBase64EncodedString); using(MemoryStream ms = new MemoryStream(theData)) { BinaryReader theReader = new BinaryReader(ms); DecodeAttachment(theReader); } } private void DecodeAttachment(BinaryReader theReader) { //Position the reader to obtain the file size. byte[] headerData = new byte[FIXED_HEADER]; headerData = theReader.ReadBytes(headerData.Length); fileSize = (int)theReader.ReadUInt32(); attachmentNameLength = (int)theReader.ReadUInt32() * 2; byte[] fileNameBytes = theReader.ReadBytes(attachmentNameLength); //InfoPath uses UTF8 encoding. Encoding enc = Encoding.Unicode; attachmentName = enc.GetString(fileNameBytes, 0, attachmentNameLength - 2); decodedAttachment = theReader.ReadBytes(fileSize); } public void SaveAttachment(string saveLocation) { string fullFileName = saveLocation; if (!fullFileName.EndsWith(Path.DirectorySeparatorChar.ToString())) { fullFileName += Path.DirectorySeparatorChar; } fullFileName += attachmentName; if(File.Exists(fullFileName)) File.Delete(fullFileName); FileStream fs = new FileStream(fullFileName, FileMode.CreateNew); BinaryWriter bw = new BinaryWriter(fs); bw.Write(decodedAttachment); bw.Close(); fs.Close(); } public string Filename { get{ return attachmentName; } } public byte[] DecodedAttachment { get{ return decodedAttachment; } } } }