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WCF and Email Attachments

First off I want to apologize for being away so long. It has been a crazy ride to say the least.

So a colleague of mine ran into an issue with WCF and emailing attachments and asked for help. In this block of code below it would always fail at:

Attachment attachment = new Attachment(fileAttachment.ContentStream, fileAttachment.Name);”     The error is : “Value cannot be null.
Parameter name: stream”

 

 

 
EmailSendInput emailSendInput = new EmailSendInput
                {
                    Attachments = new List<Attachment>(),
                    Body = model.Body,
                    To = new List<string> { model.EmailTo },
                    From = model.EmailFrom,
                    Subject = model.EmailSubject
                };

                if (model.Files != null)
                {
                    foreach (var currAttachment in model.Files)
                    {
                        if (currAttachment != null && currAttachment.ContentLength > 0)
                        {
                            // the filename needs to be nice looking
                            string fileName =
                                currAttachment.FileName.Substring(
                                    currAttachment.FileName.LastIndexOf(@”\”, System.StringComparison.Ordinal) + 1,
                                    currAttachment.FileName.Length
                                    – currAttachment.FileName.LastIndexOf(@”\”, System.StringComparison.Ordinal) – 1);

                            var attachment = new Attachment(currAttachment.InputStream, fileName);
                            emailSendInput.Attachments.Add(attachment);
                        }
                    }
                }

                B2BMortgageDataServiceAgent b2BMortgageDataServiceAgent = new B2BMortgageDataServiceAgent();
                EmailSendResponse emailSendResponse = b2BMortgageDataServiceAgent.SendEmail(emailSendInput);
                if (!emailSendResponse.Success)
                {
                    throw new Exception(emailSendResponse.Message);
                }
            }

public EmailSendResponse SendEmail(EmailSendInput input)
        {
            EmailSendResponse retVal = new EmailSendResponse();
            try
            {
               
                string smtpServer = “”
                string smtpPort = “”

                using (var client = new SmtpClient(smtpServer, Convert.ToInt32(smtpPort)))
                {
                    var mail = new MailMessage
                    {
                        From = new MailAddress(input.From),
                        Subject = input.Subject,
                        Body = input.Body
                    };
                    input.To.ForEach(t => mail.To.Add(t));

                    if (input.Attachments != null && input.Attachments.Count > 0)
                    {
                        foreach (var fileAttachment in input.Attachments)
                        {
                            //Code Crashes here
                            Attachment attachment = new Attachment(fileAttachment.ContentStream, fileAttachment.Name);
                            mail.Attachments.Add(attachment);
                        }
                    }

                    client.Send(mail);
                }

                retVal.Success = true;
            }
            catch (Exception exception)
            {
                retVal.Success = false;
                LogUtil.LogException(exception);

            
                retVal.Message = exception.ToString();
            }

            return retVal;
        }

and then the contract:

[DataContract]
    public class EmailSendInput
    {
        [DataMember]
        public string From { get; set; }

        [DataMember]
        public List<string> To { get; set; }

        [DataMember]
        public string Subject { get; set; }

        [DataMember]
        public string Body { get; set; }

        [DataMember]
        public List<Attachment> Attachments { get; set; }

    }

Implemented as:

public EmailSendResponse SendEmail(EmailSendInput input)
         {
             try
             {
                 return this.dataAgent.SendEmail(input);
             }
             catch (Exception e)
             {
                 this.logger.LogException(e, 2);
                 throw new FaultException(“An error occured in SendEmail. Error details : ” + this.BuildMessage(e));
             } 
         }

and the Email response:

[DataContract]
    public class EmailSendResponse
    {
        [DataMember]
        public bool Success { get; set; }

        [DataMember]
        public string Message { get; set; }
    }

So now we have the problem. I basically had to recreate his datamember for attachment in the contract EmailSendInput to a

public List<EmailEncodedAttachment> Attachments { get; set; }

and added a new contract called EmailEncodedAttachment and process how he was handling the attachment differently. I’ve also included the MVC controller calls in case it might help you as well.

 

SOLUTION:

[DataContract]
    public class EmailSendInput
    {
        [DataMember]
        public string From { get; set; }

        [DataMember]
        public List<string> To { get; set; }

        [DataMember]
        public string Subject { get; set; }

        [DataMember]
        public string Body { get; set; }

        [DataMember]
        public List<EmailEncodedAttachment> Attachments { get; set; }

    }

 

[DataContract]
    public class EmailEncodedAttachment
    {
        [DataMember]
        public string Base64Attachment;

        [DataMember]
        public string Name;

        /// <summary>
        /// One of the System.Net.Mime.MediaTypeNames
        /// </summary>
        [DataMember]
        public string MediaType;
    }
}
                retVal.Message = exception.ToString();
            }

            return retVal;
        }

 

public EmailSendResponse SendEmail(EmailSendInput input)
        {
            EmailSendResponse retVal = new EmailSendResponse();
            try
            {
               
                string smtpServer = ConfigurationManager.AppSettings[“SmtpServer”] ?? “url”;
                string smtpPort = ConfigurationManager.AppSettings[“SmtpPort”] ?? “portnum”;

                using (var client = new SmtpClient(smtpServer, Convert.ToInt32(smtpPort)))
                {
                    var mail = new MailMessage
                    {
                        From = new MailAddress(input.From),
                        Subject = input.Subject,
                        Body = input.Body
                    };
                    input.To.ForEach(t => mail.To.Add(t));

                    if (input.Attachments != null && input.Attachments.Count > 0)
                    {
                        foreach (var fileAttachment in input.Attachments)
                        {
                            mail.Attachments.Add(this.CreateAttachment(fileAttachment));
                        }
                    }

                    client.Send(mail);
                }

                retVal.Success = true;
            }
            catch (Exception exception)
            {
                retVal.Success = false;
                LogUtil.LogException(exception);
             
                retVal.Message = exception.ToString();
            }

            return retVal;
        }

 

The MVC controller action calls the service like so:

EmailSendInput emailSendInput = new EmailSendInput
                {
                    Attachments = new List<EmailEncodedAttachment>(),
                    Body = model.Body,
                    To = new List<string> { model.EmailTo },
                    From = model.EmailFrom,
                    Subject = model.EmailSubject
                };

                if (model.Files != null)
                {
                    foreach (var file in model.Files)
                    {
                        if (file != null && file.ContentLength > 0)
                        {
                            // the filename needs to be nice looking
                            string prettyFileName =
                                file.FileName.Substring(
                                    file.FileName.LastIndexOf(@”\”, System.StringComparison.Ordinal) + 1,
                                    file.FileName.Length
                                    – file.FileName.LastIndexOf(@”\”, System.StringComparison.Ordinal) – 1);

                            var attachment = this.CreateAttachment(prettyFileName, file.InputStream);
                            emailSendInput.Attachments.Add(attachment);
                        }
                    }
                }

                B2BMortgageDataServiceAgent b2BMortgageDataServiceAgent = new B2BMortgageDataServiceAgent();
                EmailSendResponse emailSendResponse = b2BMortgageDataServiceAgent.SendEmail(emailSendInput);
                if (!emailSendResponse.Success)
                {
                    throw new Exception(emailSendResponse.Message);
                }

 

and finally the encoding method which makes this possible:

private EmailEncodedAttachment CreateAttachment(string fileName, Stream stream)
        {
            EmailEncodedAttachment att = new EmailEncodedAttachment
            {
                Name = fileName,
                MediaType = System.Net.Mime.MediaTypeNames.Text.Plain
            };

            byte[] buffer = new byte[stream.Length];
            stream.Read(buffer, 0, (int)stream.Length);
            att.Base64Attachment = Convert.ToBase64String(buffer);

            return att;
        }

 

There you have it folks. I hope you have a great Sunday!

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Encryption and Decryption of strings with C#

Well I am checking out the Beale Street Historic District for the first time in Memphis, TN tonight. I have heard a lot about it since my arrival here so am excited to get to go. I think it will be fun.

Of course this would come up. I had written this previously in vb.net and I had the opportunity to use it again today. Of course in doing so, I discovered a bad coding practice violation I had committed. I had failed to return a value in my function’s Catch block of my code. C# doesn’t let you off the hook so easily and will bug you till you fix it. As noted previously, topic is encryption and decryption of strings. It is straightforward but you might find it useful. Simply pass in the string you want to encrypt/decrypt and the key you want to use.

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;
public class Crypto
{
    private static TripleDESCryptoServiceProvider DES = new TripleDESCryptoServiceProvider();
    private static MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
    public static byte[] MD5Hash(string value)
    {
        return MD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(value));
    }
    public static string Encrypt(string stringToEncrypt, string key)
    {
        DES.Key = Crypto.MD5Hash(key);
        DES.Mode = CipherMode.ECB;
        byte[] Buffer = ASCIIEncoding.ASCII.GetBytes(stringToEncrypt);
        return Convert.ToBase64String(DES.CreateEncryptor().TransformFinalBlock(Buffer, 0, Buffer.Length));
    }
    public static string Decrypt(string encryptedString, string key)
    {
        try
        {
            DES.Key = Crypto.MD5Hash(key);
            DES.Mode = CipherMode.ECB;
            byte[] Buffer = Convert.FromBase64String(encryptedString);
            return ASCIIEncoding.ASCII.GetString(DES.CreateDecryptor().TransformFinalBlock(Buffer, 0, Buffer.Length));
        }
        catch (Exception ex)
        {
            MessageBox.Show(“Invalid Key”, “Decryption Failed”, MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
        }
// Inserted the following ‘return’ since all code paths must return a value in C#:
        return null;
    }
}

And now it’s usage…..

public class Form1
{
    private void Button1_Click(object sender, System.EventArgs e)
    {
        string key = Microsoft.VisualBasic.Interaction.InputBox(“Enter a Key:”, “”, “”, -1, -1);
        Label1.Text = Crypto.Encrypt(TextBox1.Text, key);
        TextBox1.Clear();
    }
    private void Button2_Click(object sender, System.EventArgs e)
    {
        string key = Microsoft.VisualBasic.Interaction.InputBox(“Enter a Key:”, “”, “”, -1, -1);
        TextBox1.Text = Crypto.Decrypt(Label1.Text, key);
    }

    }


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