mcs/class/System/System.Net.Mail/SmtpClient.cs

   1 //
   2 // System.Net.Mail.SmtpClient.cs
   3 //
   4 // Author:
   5 //      Tim Coleman (tim@timcoleman.com)
   6 //
   7 // Copyright (C) Tim Coleman, 2004
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 #if SECURITY_DEP
  32 #if MONO_SECURITY_ALIAS
  33 extern alias MonoSecurity;
  34 #endif
  35 #if MONO_X509_ALIAS
  36 extern alias PrebuiltSystem;
  37 #endif
  38
  39 #if MONO_SECURITY_ALIAS
  40 using MSI = MonoSecurity::Mono.Security.Interface;
  41 #else
  42 using MSI = Mono.Security.Interface;
  43 #endif
  44 #if MONO_X509_ALIAS
  45 using X509CertificateCollection = PrebuiltSystem::System.Security.Cryptography.X509Certificates.X509CertificateCollection;
  46 #else
  47 using X509CertificateCollection = System.Security.Cryptography.X509Certificates.X509CertificateCollection;
  48 #endif
  49 using System.Security.Cryptography.X509Certificates;
  50 #endif
  51
  52 using System;
  53 using System.Collections.Generic;
  54 using System.ComponentModel;
  55 using System.Globalization;
  56 using System.IO;
  57 using System.Net;
  58 using System.Net.Mime;
  59 using System.Net.Sockets;
  60 using System.Text;
  61 using System.Threading;
  62 using System.Net.Configuration;
  63 using System.Configuration;
  64 using System.Net.Security;
  65 using System.Security.Authentication;
  66 using System.Threading.Tasks;
  67 using Mono.Net.Security;
  68
  69 namespace System.Net.Mail {
  70         [Obsolete ("SmtpClient and its network of types are poorly designed, we strongly recommend you use https://github.com/jstedfast/MailKit and https://github.com/jstedfast/MimeKit instead")]
  71         public class SmtpClient
  72         : IDisposable
  73         {
  74                 #region Fields
  75
  76                 string host;
  77                 int port;
  78                 int timeout = 100000;
  79                 ICredentialsByHost credentials;
  80                 string pickupDirectoryLocation;
  81                 SmtpDeliveryMethod deliveryMethod;
  82                 bool enableSsl;
  83 #if SECURITY_DEP
  84                 X509CertificateCollection clientCertificates;
  85 #endif
  86
  87                 TcpClient client;
  88                 Stream stream;
  89                 StreamWriter writer;
  90                 StreamReader reader;
  91                 int boundaryIndex;
  92                 MailAddress defaultFrom;
  93
  94                 MailMessage messageInProcess;
  95
  96                 BackgroundWorker worker;
  97                 object user_async_state;
  98
  99                 [Flags]
 100                 enum AuthMechs {
 101                         None        = 0,
 102                         Login       = 0x01,
 103                         Plain       = 0x02,
 104                 }
 105
 106                 class CancellationException : Exception
 107                 {
 108                 }
 109
 110                 AuthMechs authMechs;
 111                 Mutex mutex = new Mutex ();
 112
 113                 #endregion // Fields
 114
 115                 #region Constructors
 116
 117                 public SmtpClient ()
 118                         : this (null, 0)
 119                 {
 120                 }
 121
 122                 public SmtpClient (string host)
 123                         : this (host, 0)
 124                 {
 125                 }
 126
 127                 public SmtpClient (string host, int port) {
 128 #if CONFIGURATION_DEP
 129                         SmtpSection cfg = (SmtpSection) ConfigurationManager.GetSection ("system.net/mailSettings/smtp");
 130
 131                         if (cfg != null) {
 132                                 this.host = cfg.Network.Host;
 133                                 this.port = cfg.Network.Port;
 134                                 this.enableSsl = cfg.Network.EnableSsl;
 135                                 TargetName = cfg.Network.TargetName;
 136                                 if (this.TargetName == null)
 137                                         TargetName = "SMTPSVC/" + (host != null ? host : "");
 138
 139
 140                                 if (cfg.Network.UserName != null) {
 141                                         string password = String.Empty;
 142
 143                                         if (cfg.Network.Password != null)
 144                                                 password = cfg.Network.Password;
 145
 146                                         Credentials = new CCredentialsByHost (cfg.Network.UserName, password);
 147                                 }
 148
 149                                 if (!String.IsNullOrEmpty (cfg.From))
 150                                         defaultFrom = new MailAddress (cfg.From);
 151                         }
 152 #else
 153                         // Just to eliminate the warning, this codepath does not end up in production.
 154                         defaultFrom = null;
 155 #endif
 156
 157                         if (!String.IsNullOrEmpty (host))
 158                                 this.host = host;
 159
 160                         if (port != 0)
 161                                 this.port = port;
 162                         else if (this.port == 0)
 163                                 this.port = 25;
 164                 }
 165
 166                 #endregion // Constructors
 167
 168                 #region Properties
 169
 170 #if SECURITY_DEP
 171                 [MonoTODO("Client certificates not used")]
 172                 public X509CertificateCollection ClientCertificates {
 173                         get {
 174                                 if (clientCertificates == null)
 175                                         clientCertificates = new X509CertificateCollection ();
 176                                 return clientCertificates;
 177                         }
 178                 }
 179 #endif
 180
 181                 public
 182                 string TargetName { get; set; }
 183
 184                 public ICredentialsByHost Credentials {
 185                         get { return credentials; }
 186                         set {
 187                                 CheckState ();
 188                                 credentials = value;
 189                         }
 190                 }
 191
 192                 public SmtpDeliveryMethod DeliveryMethod {
 193                         get { return deliveryMethod; }
 194                         set {
 195                                 CheckState ();
 196                                 deliveryMethod = value;
 197                         }
 198                 }
 199
 200                 public bool EnableSsl {
 201                         get { return enableSsl; }
 202                         set {
 203                                 CheckState ();
 204                                 enableSsl = value;
 205                         }
 206                 }
 207
 208                 public string Host {
 209                         get { return host; }
 210                         set {
 211                                 if (value == null)
 212                                         throw new ArgumentNullException ("value");
 213                                 if (value.Length == 0)
 214                                         throw new ArgumentException ("An empty string is not allowed.", "value");
 215                                 CheckState ();
 216                                 host = value;
 217                         }
 218                 }
 219
 220                 public string PickupDirectoryLocation {
 221                         get { return pickupDirectoryLocation; }
 222                         set { pickupDirectoryLocation = value; }
 223                 }
 224
 225                 public int Port {
 226                         get { return port; }
 227                         set {
 228                                 if (value <= 0)
 229                                         throw new ArgumentOutOfRangeException ("value");
 230                                 CheckState ();
 231                                 port = value;
 232                         }
 233                 }
 234
 235                 [MonoTODO]
 236                 public ServicePoint ServicePoint {
 237                         get { throw new NotImplementedException (); }
 238                 }
 239
 240                 public int Timeout {
 241                         get { return timeout; }
 242                         set {
 243                                 if (value < 0)
 244                                         throw new ArgumentOutOfRangeException ("value");
 245                                 CheckState ();
 246                                 timeout = value;
 247                         }
 248                 }
 249
 250                 public bool UseDefaultCredentials {
 251                         get { return false; }
 252                         [MonoNotSupported ("no DefaultCredential support in Mono")]
 253                         set {
 254                                 if (value)
 255                                         throw new NotImplementedException ("Default credentials are not supported");
 256                                 CheckState ();
 257                         }
 258                 }
 259
 260                 #endregion // Properties
 261
 262                 #region Events
 263
 264                 public event SendCompletedEventHandler SendCompleted;
 265
 266                 #endregion // Events
 267
 268                 #region Methods
 269                 public void Dispose ()
 270                 {
 271                         Dispose (true);
 272                 }
 273
 274                 [MonoTODO ("Does nothing at the moment.")]
 275                 protected virtual void Dispose (bool disposing)
 276                 {
 277                         // TODO: We should close all the connections and abort any async operations here
 278                 }
 279                 private void CheckState ()
 280                 {
 281                         if (messageInProcess != null)
 282                                 throw new InvalidOperationException ("Cannot set Timeout while Sending a message");
 283                 }
 284
 285                 private static string EncodeAddress(MailAddress address)
 286                 {
 287                         if (!String.IsNullOrEmpty (address.DisplayName)) {
 288                                 string encodedDisplayName = ContentType.EncodeSubjectRFC2047 (address.DisplayName, Encoding.UTF8);
 289                                 return "\"" + encodedDisplayName + "\" <" + address.Address + ">";
 290                         }
 291                         return address.ToString ();
 292                 }
 293
 294                 private static string EncodeAddresses(MailAddressCollection addresses)
 295                 {
 296                         StringBuilder sb = new StringBuilder();
 297                         bool first = true;
 298                         foreach (MailAddress address in addresses) {
 299                                 if (!first) {
 300                                         sb.Append(", ");
 301                                 }
 302                                 sb.Append(EncodeAddress(address));
 303                                 first = false;
 304                         }
 305                         return sb.ToString();
 306                 }
 307
 308                 private string EncodeSubjectRFC2047 (MailMessage message)
 309                 {
 310                         return ContentType.EncodeSubjectRFC2047 (message.Subject, message.SubjectEncoding);
 311                 }
 312
 313                 private string EncodeBody (MailMessage message)
 314                 {
 315                         string body = message.Body;
 316                         Encoding encoding = message.BodyEncoding;
 317                         // RFC 2045 encoding
 318                         switch (message.ContentTransferEncoding) {
 319                         case TransferEncoding.SevenBit:
 320                                 return body;
 321                         case TransferEncoding.Base64:
 322                                 return Convert.ToBase64String (encoding.GetBytes (body), Base64FormattingOptions.InsertLineBreaks);
 323                         default:
 324                                 return ToQuotedPrintable (body, encoding);
 325                         }
 326                 }
 327
 328                 private string EncodeBody (AlternateView av)
 329                 {
 330                         //Encoding encoding = av.ContentType.CharSet != null ? Encoding.GetEncoding (av.ContentType.CharSet) : Encoding.UTF8;
 331
 332                         byte [] bytes = new byte [av.ContentStream.Length];
 333                         av.ContentStream.Read (bytes, 0, bytes.Length);
 334
 335                         // RFC 2045 encoding
 336                         switch (av.TransferEncoding) {
 337                         case TransferEncoding.SevenBit:
 338                                 return Encoding.ASCII.GetString (bytes);
 339                         case TransferEncoding.Base64:
 340                                 return Convert.ToBase64String (bytes, Base64FormattingOptions.InsertLineBreaks);
 341                         default:
 342                                 return ToQuotedPrintable (bytes);
 343                         }
 344                 }
 345
 346
 347                 private void EndSection (string section)
 348                 {
 349                         SendData (String.Format ("--{0}--", section));
 350                         SendData (string.Empty);
 351                 }
 352
 353                 private string GenerateBoundary ()
 354                 {
 355                         string output = GenerateBoundary (boundaryIndex);
 356                         boundaryIndex += 1;
 357                         return output;
 358                 }
 359
 360                 private static string GenerateBoundary (int index)
 361                 {
 362                         return String.Format ("--boundary_{0}_{1}", index, Guid.NewGuid ().ToString ("D"));
 363                 }
 364
 365                 private bool IsError (SmtpResponse status)
 366                 {
 367                         return ((int) status.StatusCode) >= 400;
 368                 }
 369
 370                 protected void OnSendCompleted (AsyncCompletedEventArgs e)
 371                 {
 372                         try {
 373                                 if (SendCompleted != null)
 374                                         SendCompleted (this, e);
 375                         } finally {
 376                                 worker = null;
 377                                 user_async_state = null;
 378                         }
 379                 }
 380
 381                 private void CheckCancellation ()
 382                 {
 383                         if (worker != null && worker.CancellationPending)
 384                                 throw new CancellationException ();
 385                 }
 386
 387                 private SmtpResponse Read () {
 388                         byte [] buffer = new byte [512];
 389                         int position = 0;
 390                         bool lastLine = false;
 391
 392                         do {
 393                                 CheckCancellation ();
 394
 395                                 int readLength = stream.Read (buffer, position, buffer.Length - position);
 396                                 if (readLength > 0) {
 397                                         int available = position + readLength - 1;
 398                                         if (available > 4 && (buffer [available] == '\n' || buffer [available] == '\r'))
 399                                                 for (int index = available - 3; ; index--) {
 400                                                         if (index < 0 || buffer [index] == '\n' || buffer [index] == '\r') {
 401                                                                 lastLine = buffer [index + 4] == ' ';
 402                                                                 break;
 403                                                         }
 404                                                 }
 405
 406                                         // move position
 407                                         position += readLength;
 408
 409                                         // check if buffer is full
 410                                         if (position == buffer.Length) {
 411                                                 byte [] newBuffer = new byte [buffer.Length * 2];
 412                                                 Array.Copy (buffer, 0, newBuffer, 0, buffer.Length);
 413                                                 buffer = newBuffer;
 414                                         }
 415                                 }
 416                                 else {
 417                                         break;
 418                                 }
 419                         } while (!lastLine);
 420
 421                         if (position > 0) {
 422                                 Encoding encoding = new ASCIIEncoding ();
 423
 424                                 string line = encoding.GetString (buffer, 0, position - 1);
 425
 426                                 // parse the line to the lastResponse object
 427                                 SmtpResponse response = SmtpResponse.Parse (line);
 428
 429                                 return response;
 430                         } else {
 431                                 throw new System.IO.IOException ("Connection closed");
 432                         }
 433                 }
 434
 435                 void ResetExtensions()
 436                 {
 437                         authMechs = AuthMechs.None;
 438                 }
 439
 440                 void ParseExtensions (string extens)
 441                 {
 442                         string[] parts = extens.Split ('\n');
 443
 444                         foreach (string part in parts) {
 445                                 if (part.Length < 4)
 446                                         continue;
 447
 448                                 string start = part.Substring (4);
 449                                 if (start.StartsWith ("AUTH ", StringComparison.Ordinal)) {
 450                                         string[] options = start.Split (' ');
 451                                         for (int k = 1; k < options.Length; k++) {
 452                                                 string option = options[k].Trim();
 453                                                 // GSSAPI, KERBEROS_V4, NTLM not supported
 454                                                 switch (option) {
 455                                                 /*
 456                                                 case "CRAM-MD5":
 457                                                         authMechs |= AuthMechs.CramMD5;
 458                                                         break;
 459                                                 case "DIGEST-MD5":
 460                                                         authMechs |= AuthMechs.DigestMD5;
 461                                                         break;
 462                                                 */
 463                                                 case "LOGIN":
 464                                                         authMechs |= AuthMechs.Login;
 465                                                         break;
 466                                                 case "PLAIN":
 467                                                         authMechs |= AuthMechs.Plain;
 468                                                         break;
 469                                                 }
 470                                         }
 471                                 }
 472                         }
 473                 }
 474
 475                 public void Send (MailMessage message)
 476                 {
 477                         if (message == null)
 478                                 throw new ArgumentNullException ("message");
 479
 480                         if (deliveryMethod == SmtpDeliveryMethod.Network && (Host == null || Host.Trim ().Length == 0))
 481                                 throw new InvalidOperationException ("The SMTP host was not specified");
 482                         else if (deliveryMethod == SmtpDeliveryMethod.PickupDirectoryFromIis)
 483                                 throw new NotSupportedException("IIS delivery is not supported");
 484
 485                         if (port == 0)
 486                                 port = 25;
 487
 488                         // Block while sending
 489                         mutex.WaitOne ();
 490                         try {
 491                                 messageInProcess = message;
 492                                 if (deliveryMethod == SmtpDeliveryMethod.SpecifiedPickupDirectory)
 493                                         SendToFile (message);
 494                                 else
 495                                         SendInternal (message);
 496                         } catch (CancellationException) {
 497                                 // This exception is introduced for convenient cancellation process.
 498                         } catch (SmtpException) {
 499                                 throw;
 500                         } catch (Exception ex) {
 501                                 throw new SmtpException ("Message could not be sent.", ex);
 502                         } finally {
 503                                 // Release the mutex to allow other threads access
 504                                 mutex.ReleaseMutex ();
 505                                 messageInProcess = null;
 506                         }
 507                 }
 508
 509                 private void SendInternal (MailMessage message)
 510                 {
 511                         CheckCancellation ();
 512
 513                         try {
 514                                 client = new TcpClient (host, port);
 515                                 stream = client.GetStream ();
 516                                 // FIXME: this StreamWriter creation is bogus.
 517                                 // It expects as if a Stream were able to switch to SSL
 518                                 // mode (such behavior is only in Mainsoft Socket API).
 519                                 writer = new StreamWriter (stream);
 520                                 reader = new StreamReader (stream);
 521
 522                                 SendCore (message);
 523                         } finally {
 524                                 if (writer != null)
 525                                         writer.Close ();
 526                                 if (reader != null)
 527                                         reader.Close ();
 528                                 if (stream != null)
 529                                         stream.Close ();
 530                                 if (client != null)
 531                                         client.Close ();
 532                         }
 533                 }
 534
 535                 // FIXME: simple implementation, could be brushed up.
 536                 private void SendToFile (MailMessage message)
 537                 {
 538                         if (!Path.IsPathRooted (pickupDirectoryLocation))
 539                                 throw new SmtpException("Only absolute directories are allowed for pickup directory.");
 540
 541                         string filename = Path.Combine (pickupDirectoryLocation,
 542                                 Guid.NewGuid() + ".eml");
 543
 544                         try {
 545                                 writer = new StreamWriter(filename);
 546
 547                                 // FIXME: See how Microsoft fixed the bug about envelope senders, and how it actually represents the info in .eml file headers
 548                                 //        For all we know, defaultFrom may be the envelope sender
 549                                 // For now, we are no worse than some versions of .NET
 550                                 MailAddress from = message.From;
 551                                 if (from == null)
 552                                         from = defaultFrom;
 553
 554                                 string dt = DateTime.Now.ToString("ddd, dd MMM yyyy HH':'mm':'ss zzz", DateTimeFormatInfo.InvariantInfo);
 555                                 // remove ':' from time zone offset (e.g. from "+01:00")
 556                                 dt = dt.Remove(dt.Length - 3, 1);
 557                                 SendHeader(HeaderName.Date, dt);
 558
 559                                 SendHeader (HeaderName.From, EncodeAddress(from));
 560                                 SendHeader (HeaderName.To, EncodeAddresses(message.To));
 561                                 if (message.CC.Count > 0)
 562                                         SendHeader (HeaderName.Cc, EncodeAddresses(message.CC));
 563                                 SendHeader (HeaderName.Subject, EncodeSubjectRFC2047 (message));
 564
 565                                 foreach (string s in message.Headers.AllKeys)
 566                                         SendHeader (s, message.Headers [s]);
 567
 568                                 AddPriorityHeader (message);
 569
 570                                 boundaryIndex = 0;
 571                                 if (message.Attachments.Count > 0)
 572                                         SendWithAttachments (message);
 573                                 else
 574                                         SendWithoutAttachments (message, null, false);
 575
 576
 577                         } finally {
 578                                 if (writer != null) writer.Close(); writer = null;
 579                         }
 580                 }
 581
 582                 private void SendCore (MailMessage message)
 583                 {
 584                         SmtpResponse status;
 585
 586                         status = Read ();
 587                         if (IsError (status))
 588                                 throw new SmtpException (status.StatusCode, status.Description);
 589
 590                         // EHLO
 591
 592                         // FIXME: parse the list of extensions so we don't bother wasting
 593                         // our time trying commands if they aren't supported.
 594
 595                         // Get the FQDN of the local machine
 596                         string fqdn = Dns.GetHostEntry (Dns.GetHostName ()).HostName;
 597                         status = SendCommand ("EHLO " + fqdn);
 598
 599                         if (IsError (status)) {
 600                                 status = SendCommand ("HELO " + fqdn);
 601
 602                                 if (IsError (status))
 603                                         throw new SmtpException (status.StatusCode, status.Description);
 604                         } else {
 605                                 // Parse ESMTP extensions
 606                                 string extens = status.Description;
 607
 608                                 if (extens != null)
 609                                         ParseExtensions (extens);
 610                         }
 611
 612                         if (enableSsl) {
 613                                 InitiateSecureConnection ();
 614                                 ResetExtensions();
 615                                 writer = new StreamWriter (stream);
 616                                 reader = new StreamReader (stream);
 617                                 status = SendCommand ("EHLO " + fqdn);
 618
 619                                 if (IsError (status)) {
 620                                         status = SendCommand ("HELO " + fqdn);
 621
 622                                         if (IsError (status))
 623                                                 throw new SmtpException (status.StatusCode, status.Description);
 624                                 } else {
 625                                         // Parse ESMTP extensions
 626                                         string extens = status.Description;
 627                                         if (extens != null)
 628                                                 ParseExtensions (extens);
 629                                 }
 630                         }
 631
 632                         if (authMechs != AuthMechs.None)
 633                                 Authenticate ();
 634
 635                         // The envelope sender: use 'Sender:' in preference of 'From:'
 636                         MailAddress sender = message.Sender;
 637                         if (sender == null)
 638                                 sender = message.From;
 639                         if (sender == null)
 640                                 sender = defaultFrom;
 641
 642                         // MAIL FROM:
 643                         status = SendCommand ("MAIL FROM:<" + sender.Address + '>');
 644                         if (IsError (status)) {
 645                                 throw new SmtpException (status.StatusCode, status.Description);
 646                         }
 647
 648                         // Send RCPT TO: for all recipients
 649                         List<SmtpFailedRecipientException> sfre = new List<SmtpFailedRecipientException> ();
 650
 651                         for (int i = 0; i < message.To.Count; i ++) {
 652                                 status = SendCommand ("RCPT TO:<" + message.To [i].Address + '>');
 653                                 if (IsError (status))
 654                                         sfre.Add (new SmtpFailedRecipientException (status.StatusCode, message.To [i].Address));
 655                         }
 656                         for (int i = 0; i < message.CC.Count; i ++) {
 657                                 status = SendCommand ("RCPT TO:<" + message.CC [i].Address + '>');
 658                                 if (IsError (status))
 659                                         sfre.Add (new SmtpFailedRecipientException (status.StatusCode, message.CC [i].Address));
 660                         }
 661                         for (int i = 0; i < message.Bcc.Count; i ++) {
 662                                 status = SendCommand ("RCPT TO:<" + message.Bcc [i].Address + '>');
 663                                 if (IsError (status))
 664                                         sfre.Add (new SmtpFailedRecipientException (status.StatusCode, message.Bcc [i].Address));
 665                         }
 666
 667                         if (sfre.Count >0)
 668                                 throw new SmtpFailedRecipientsException ("failed recipients", sfre.ToArray ());
 669
 670                         // DATA
 671                         status = SendCommand ("DATA");
 672                         if (IsError (status))
 673                                 throw new SmtpException (status.StatusCode, status.Description);
 674
 675                         // Send message headers
 676                         string dt = DateTime.Now.ToString ("ddd, dd MMM yyyy HH':'mm':'ss zzz", DateTimeFormatInfo.InvariantInfo);
 677                         // remove ':' from time zone offset (e.g. from "+01:00")
 678                         dt = dt.Remove (dt.Length - 3, 1);
 679                         SendHeader (HeaderName.Date, dt);
 680
 681                         MailAddress from = message.From;
 682                         if (from == null)
 683                                 from = defaultFrom;
 684
 685                         SendHeader (HeaderName.From, EncodeAddress (from));
 686                         SendHeader (HeaderName.To, EncodeAddresses (message.To));
 687                         if (message.CC.Count > 0)
 688                                 SendHeader (HeaderName.Cc, EncodeAddresses (message.CC));
 689                         SendHeader (HeaderName.Subject, EncodeSubjectRFC2047 (message));
 690
 691                         string v = "normal";
 692
 693                         switch (message.Priority){
 694                         case MailPriority.Normal:
 695                                 v = "normal";
 696                                 break;
 697
 698                         case MailPriority.Low:
 699                                 v = "non-urgent";
 700                                 break;
 701
 702                         case MailPriority.High:
 703                                 v = "urgent";
 704                                 break;
 705                         }
 706                         SendHeader ("Priority", v);
 707                         if (message.Sender != null)
 708                                 SendHeader ("Sender", EncodeAddress (message.Sender));
 709                         if (message.ReplyToList.Count > 0)
 710                                 SendHeader ("Reply-To", EncodeAddresses (message.ReplyToList));
 711
 712                         foreach (string s in message.Headers.AllKeys)
 713                                 SendHeader (s, ContentType.EncodeSubjectRFC2047 (message.Headers [s], message.HeadersEncoding));
 714
 715                         AddPriorityHeader (message);
 716
 717                         boundaryIndex = 0;
 718                         if (message.Attachments.Count > 0)
 719                                 SendWithAttachments (message);
 720                         else
 721                                 SendWithoutAttachments (message, null, false);
 722
 723                         SendDot ();
 724
 725                         status = Read ();
 726                         if (IsError (status))
 727                                 throw new SmtpException (status.StatusCode, status.Description);
 728
 729                         try {
 730                                 status = SendCommand ("QUIT");
 731                         } catch (System.IO.IOException) {
 732                                 // We excuse server for the rude connection closing as a response to QUIT
 733                         }
 734                 }
 735
 736                 public void Send (string from, string to, string subject, string body)
 737                 {
 738                         Send (new MailMessage (from, to, subject, body));
 739                 }
 740
 741                 public Task SendMailAsync (MailMessage message)
 742                 {
 743                         var tcs = new TaskCompletionSource<object> ();
 744                         SendCompletedEventHandler handler = null;
 745                         handler = (s, e) => SendMailAsyncCompletedHandler (tcs, e, handler, this);
 746                         SendCompleted += handler;
 747                         SendAsync (message, tcs);
 748                         return tcs.Task;
 749                 }
 750
 751                 public Task SendMailAsync (string from, string recipients, string subject, string body)
 752                 {
 753                         return SendMailAsync (new MailMessage (from, recipients, subject, body));
 754                 }
 755
 756                 static void SendMailAsyncCompletedHandler (TaskCompletionSource<object> source, AsyncCompletedEventArgs e, SendCompletedEventHandler handler, SmtpClient client)
 757                 {
 758                         if (source != e.UserState)
 759                                 return;
 760
 761                         client.SendCompleted -= handler;
 762
 763                         if (e.Error != null) {
 764                                 source.SetException (e.Error);
 765                                 return;
 766                         }
 767
 768                         if (e.Cancelled) {
 769                                 source.SetCanceled ();
 770                                 return;
 771                         }
 772
 773                         source.SetResult (null);
 774                 }
 775
 776                 private void SendDot()
 777                 {
 778                         writer.Write(".\r\n");
 779                         writer.Flush();
 780                 }
 781
 782                 private void SendData (string data)
 783                 {
 784                         if (String.IsNullOrEmpty (data)) {
 785                                 writer.Write("\r\n");
 786                                 writer.Flush();
 787                                 return;
 788                         }
 789
 790                         StringReader sr = new StringReader (data);
 791                         string line;
 792                         bool escapeDots = deliveryMethod == SmtpDeliveryMethod.Network;
 793                         while ((line = sr.ReadLine ()) != null) {
 794                                 CheckCancellation ();
 795
 796                                 if (escapeDots) {
 797                                         if (line.Length > 0 && line[0] == '.') {
 798                                                 line = "." + line;
 799                                         }
 800                                 }
 801                                 writer.Write (line);
 802                                 writer.Write ("\r\n");
 803                         }
 804                         writer.Flush ();
 805                 }
 806
 807                 public void SendAsync (MailMessage message, object userToken)
 808                 {
 809                         if (worker != null)
 810                                 throw new InvalidOperationException ("Another SendAsync operation is in progress");
 811
 812                         worker = new BackgroundWorker ();
 813                         worker.DoWork += delegate (object o, DoWorkEventArgs ea) {
 814                                 try {
 815                                         user_async_state = ea.Argument;
 816                                         Send (message);
 817                                 } catch (Exception ex) {
 818                                         ea.Result = ex;
 819                                         throw ex;
 820                                 }
 821                         };
 822                         worker.WorkerSupportsCancellation = true;
 823                         worker.RunWorkerCompleted += delegate (object o, RunWorkerCompletedEventArgs ea) {
 824                                 // Note that RunWorkerCompletedEventArgs.UserState cannot be used (LAMESPEC)
 825                                 OnSendCompleted (new AsyncCompletedEventArgs (ea.Error, ea.Cancelled, user_async_state));
 826                         };
 827                         worker.RunWorkerAsync (userToken);
 828                 }
 829
 830                 public void SendAsync (string from, string to, string subject, string body, object userToken)
 831                 {
 832                         SendAsync (new MailMessage (from, to, subject, body), userToken);
 833                 }
 834
 835                 public void SendAsyncCancel ()
 836                 {
 837                         if (worker == null)
 838                                 throw new InvalidOperationException ("SendAsync operation is not in progress");
 839                         worker.CancelAsync ();
 840                 }
 841
 842                 private void AddPriorityHeader (MailMessage message) {
 843                         switch (message.Priority) {
 844                         case MailPriority.High:
 845                                 SendHeader (HeaderName.Priority, "Urgent");
 846                                 SendHeader (HeaderName.Importance, "high");
 847                                 SendHeader (HeaderName.XPriority, "1");
 848                                 break;
 849                         case MailPriority.Low:
 850                                 SendHeader (HeaderName.Priority, "Non-Urgent");
 851                                 SendHeader (HeaderName.Importance, "low");
 852                                 SendHeader (HeaderName.XPriority, "5");
 853                                 break;
 854                         }
 855                 }
 856
 857                 private void SendSimpleBody (MailMessage message) {
 858                         SendHeader (HeaderName.ContentType, message.BodyContentType.ToString ());
 859                         if (message.ContentTransferEncoding != TransferEncoding.SevenBit)
 860                                 SendHeader (HeaderName.ContentTransferEncoding, GetTransferEncodingName (message.ContentTransferEncoding));
 861                         SendData (string.Empty);
 862
 863                         SendData (EncodeBody (message));
 864                 }
 865
 866                 private void SendBodylessSingleAlternate (AlternateView av) {
 867                         SendHeader (HeaderName.ContentType, av.ContentType.ToString ());
 868                         if (av.TransferEncoding != TransferEncoding.SevenBit)
 869                                 SendHeader (HeaderName.ContentTransferEncoding, GetTransferEncodingName (av.TransferEncoding));
 870                         SendData (string.Empty);
 871
 872                         SendData (EncodeBody (av));
 873                 }
 874
 875                 private void SendWithoutAttachments (MailMessage message, string boundary, bool attachmentExists)
 876                 {
 877                         if (message.Body == null && message.AlternateViews.Count == 1)
 878                                 SendBodylessSingleAlternate (message.AlternateViews [0]);
 879                         else if (message.AlternateViews.Count > 0)
 880                                 SendBodyWithAlternateViews (message, boundary, attachmentExists);
 881                         else
 882                                 SendSimpleBody (message);
 883                 }
 884
 885
 886                 private void SendWithAttachments (MailMessage message) {
 887                         string boundary = GenerateBoundary ();
 888
 889                         // first "multipart/mixed"
 890                         ContentType messageContentType = new ContentType ();
 891                         messageContentType.Boundary = boundary;
 892                         messageContentType.MediaType = "multipart/mixed";
 893                         messageContentType.CharSet = null;
 894
 895                         SendHeader (HeaderName.ContentType, messageContentType.ToString ());
 896                         SendData (String.Empty);
 897
 898                         // body section
 899                         Attachment body = null;
 900
 901                         if (message.AlternateViews.Count > 0)
 902                                 SendWithoutAttachments (message, boundary, true);
 903                         else {
 904                                 body = Attachment.CreateAttachmentFromString (message.Body, null, message.BodyEncoding, message.IsBodyHtml ? "text/html" : "text/plain");
 905                                 message.Attachments.Insert (0, body);
 906                         }
 907
 908                         try {
 909                                 SendAttachments (message, body, boundary);
 910                         } finally {
 911                                 if (body != null)
 912                                         message.Attachments.Remove (body);
 913                         }
 914
 915                         EndSection (boundary);
 916                 }
 917
 918                 private void SendBodyWithAlternateViews (MailMessage message, string boundary, bool attachmentExists)
 919                 {
 920                         AlternateViewCollection alternateViews = message.AlternateViews;
 921
 922                         string inner_boundary = GenerateBoundary ();
 923
 924                         ContentType messageContentType = new ContentType ();
 925                         messageContentType.Boundary = inner_boundary;
 926                         messageContentType.MediaType = "multipart/alternative";
 927
 928                         if (!attachmentExists) {
 929                                 SendHeader (HeaderName.ContentType, messageContentType.ToString ());
 930                                 SendData (String.Empty);
 931                         }
 932
 933                         // body section
 934                         AlternateView body = null;
 935                         if (message.Body != null) {
 936                                 body = AlternateView.CreateAlternateViewFromString (message.Body, message.BodyEncoding, message.IsBodyHtml ? "text/html" : "text/plain");
 937                                 alternateViews.Insert (0, body);
 938                                 StartSection (boundary, messageContentType);
 939                         }
 940
 941 try {
 942                         // alternate view sections
 943                         foreach (AlternateView av in alternateViews) {
 944
 945                                 string alt_boundary = null;
 946                                 ContentType contentType;
 947                                 if (av.LinkedResources.Count > 0) {
 948                                         alt_boundary = GenerateBoundary ();
 949                                         contentType = new ContentType ("multipart/related");
 950                                         contentType.Boundary = alt_boundary;
 951
 952                                         contentType.Parameters ["type"] = av.ContentType.ToString ();
 953                                         StartSection (inner_boundary, contentType);
 954                                         StartSection (alt_boundary, av.ContentType, av);
 955                                 } else {
 956                                         contentType = new ContentType (av.ContentType.ToString ());
 957                                         StartSection (inner_boundary, contentType, av);
 958                                 }
 959
 960                                 switch (av.TransferEncoding) {
 961                                 case TransferEncoding.Base64:
 962                                         byte [] content = new byte [av.ContentStream.Length];
 963                                         av.ContentStream.Read (content, 0, content.Length);
 964                                             SendData (Convert.ToBase64String (content, Base64FormattingOptions.InsertLineBreaks));
 965                                         break;
 966                                 case TransferEncoding.QuotedPrintable:
 967                                         byte [] bytes = new byte [av.ContentStream.Length];
 968                                         av.ContentStream.Read (bytes, 0, bytes.Length);
 969                                         SendData (ToQuotedPrintable (bytes));
 970                                         break;
 971                                 case TransferEncoding.SevenBit:
 972                                 case TransferEncoding.Unknown:
 973                                         content = new byte [av.ContentStream.Length];
 974                                         av.ContentStream.Read (content, 0, content.Length);
 975                                         SendData (Encoding.ASCII.GetString (content));
 976                                         break;
 977                                 }
 978
 979                                 if (av.LinkedResources.Count > 0) {
 980                                         SendLinkedResources (message, av.LinkedResources, alt_boundary);
 981                                         EndSection (alt_boundary);
 982                                 }
 983
 984                                 if (!attachmentExists)
 985                                         SendData (string.Empty);
 986                         }
 987
 988 } finally {
 989                         if (body != null)
 990                                 alternateViews.Remove (body);
 991 }
 992                         EndSection (inner_boundary);
 993                 }
 994
 995                 private void SendLinkedResources (MailMessage message, LinkedResourceCollection resources, string boundary)
 996                 {
 997                         foreach (LinkedResource lr in resources) {
 998                                 StartSection (boundary, lr.ContentType, lr);
 999
1000                                 switch (lr.TransferEncoding) {
1001                                 case TransferEncoding.Base64:
1002                                         byte [] content = new byte [lr.ContentStream.Length];
1003                                         lr.ContentStream.Read (content, 0, content.Length);
1004                                             SendData (Convert.ToBase64String (content, Base64FormattingOptions.InsertLineBreaks));
1005                                         break;
1006                                 case TransferEncoding.QuotedPrintable:
1007                                         byte [] bytes = new byte [lr.ContentStream.Length];
1008                                         lr.ContentStream.Read (bytes, 0, bytes.Length);
1009                                         SendData (ToQuotedPrintable (bytes));
1010                                         break;
1011                                 case TransferEncoding.SevenBit:
1012                                 case TransferEncoding.Unknown:
1013                                         content = new byte [lr.ContentStream.Length];
1014                                         lr.ContentStream.Read (content, 0, content.Length);
1015                                         SendData (Encoding.ASCII.GetString (content));
1016                                         break;
1017                                 }
1018                         }
1019                 }
1020
1021                 private void SendAttachments (MailMessage message, Attachment body, string boundary) {
1022                         foreach (Attachment att in message.Attachments) {
1023                                 ContentType contentType = new ContentType (att.ContentType.ToString ());
1024                                 if (att.Name != null) {
1025                                         contentType.Name = att.Name;
1026                                         if (att.NameEncoding != null)
1027                                                 contentType.CharSet = att.NameEncoding.HeaderName;
1028                                         att.ContentDisposition.FileName = att.Name;
1029                                 }
1030                                 StartSection (boundary, contentType, att, att != body);
1031
1032                                 byte [] content = new byte [att.ContentStream.Length];
1033                                 att.ContentStream.Read (content, 0, content.Length);
1034                                 switch (att.TransferEncoding) {
1035                                 case TransferEncoding.Base64:
1036                                         SendData (Convert.ToBase64String (content, Base64FormattingOptions.InsertLineBreaks));
1037                                         break;
1038                                 case TransferEncoding.QuotedPrintable:
1039                                         SendData (ToQuotedPrintable (content));
1040                                         break;
1041                                 case TransferEncoding.SevenBit:
1042                                 case TransferEncoding.Unknown:
1043                                         SendData (Encoding.ASCII.GetString (content));
1044                                         break;
1045                                 }
1046
1047                                 SendData (string.Empty);
1048                         }
1049                 }
1050
1051                 private SmtpResponse SendCommand (string command)
1052                 {
1053                         writer.Write (command);
1054                         // Certain SMTP servers will reject mail sent with unix line-endings; see http://cr.yp.to/docs/smtplf.html
1055                         writer.Write ("\r\n");
1056                         writer.Flush ();
1057                         return Read ();
1058                 }
1059
1060                 private void SendHeader (string name, string value)
1061                 {
1062                         SendData (String.Format ("{0}: {1}", name, value));
1063                 }
1064
1065                 private void StartSection (string section, ContentType sectionContentType)
1066                 {
1067                         SendData (String.Format ("--{0}", section));
1068                         SendHeader ("content-type", sectionContentType.ToString ());
1069                         SendData (string.Empty);
1070                 }
1071
1072                 private void StartSection (string section, ContentType sectionContentType, AttachmentBase att)
1073                 {
1074                         SendData (String.Format ("--{0}", section));
1075                         SendHeader ("content-type", sectionContentType.ToString ());
1076                         SendHeader ("content-transfer-encoding", GetTransferEncodingName (att.TransferEncoding));
1077                         if (!string.IsNullOrEmpty (att.ContentId))
1078                                 SendHeader("content-ID", "<" + att.ContentId + ">");
1079                         SendData (string.Empty);
1080                 }
1081
1082                 private void StartSection (string section, ContentType sectionContentType, Attachment att, bool sendDisposition) {
1083                         SendData (String.Format ("--{0}", section));
1084                         if (!string.IsNullOrEmpty (att.ContentId))
1085                                 SendHeader("content-ID", "<" + att.ContentId + ">");
1086                         SendHeader ("content-type", sectionContentType.ToString ());
1087                         SendHeader ("content-transfer-encoding", GetTransferEncodingName (att.TransferEncoding));
1088                         if (sendDisposition)
1089                                 SendHeader ("content-disposition", att.ContentDisposition.ToString ());
1090                         SendData (string.Empty);
1091                 }
1092
1093                 // use proper encoding to escape input
1094                 private string ToQuotedPrintable (string input, Encoding enc)
1095                 {
1096                         byte [] bytes = enc.GetBytes (input);
1097                         return ToQuotedPrintable (bytes);
1098                 }
1099
1100                 private string ToQuotedPrintable (byte [] bytes)
1101                 {
1102                         StringWriter writer = new StringWriter ();
1103                         int charsInLine = 0;
1104                         int curLen;
1105                         StringBuilder sb = new StringBuilder("=", 3);
1106                         byte equalSign = (byte)'=';
1107                         char c = (char)0;
1108
1109                         foreach (byte i in bytes) {
1110                                 if (i > 127 || i == equalSign) {
1111                                         sb.Length = 1;
1112                                         sb.Append(Convert.ToString (i, 16).ToUpperInvariant ());
1113                                         curLen = 3;
1114                                 } else {
1115                                         c = Convert.ToChar (i);
1116                                         if (c == '\r' || c == '\n') {
1117                                                 writer.Write (c);
1118                                                 charsInLine = 0;
1119                                                 continue;
1120                                         }
1121                                         curLen = 1;
1122                                 }
1123
1124                                 charsInLine += curLen;
1125                                 if (charsInLine > 75) {
1126                                         writer.Write ("=\r\n");
1127                                         charsInLine = curLen;
1128                                 }
1129                                 if (curLen == 1)
1130                                         writer.Write (c);
1131                                 else
1132                                         writer.Write (sb.ToString ());
1133                         }
1134
1135                         return writer.ToString ();
1136                 }
1137                 private static string GetTransferEncodingName (TransferEncoding encoding)
1138                 {
1139                         switch (encoding) {
1140                         case TransferEncoding.QuotedPrintable:
1141                                 return "quoted-printable";
1142                         case TransferEncoding.SevenBit:
1143                                 return "7bit";
1144                         case TransferEncoding.Base64:
1145                                 return "base64";
1146                         }
1147                         return "unknown";
1148                 }
1149
1150                 private void InitiateSecureConnection () {
1151                         SmtpResponse response = SendCommand ("STARTTLS");
1152
1153                         if (IsError (response)) {
1154                                 throw new SmtpException (SmtpStatusCode.GeneralFailure, "Server does not support secure connections.");
1155                         }
1156
1157 #if SECURITY_DEP
1158                         var tlsProvider = MonoTlsProviderFactory.GetProviderInternal ();
1159                         var settings = MSI.MonoTlsSettings.CopyDefaultSettings ();
1160                         settings.UseServicePointManagerCallback = true;
1161                         var sslStream = tlsProvider.CreateSslStream (stream, false, settings);
1162                         CheckCancellation ();
1163                         sslStream.AuthenticateAsClient (Host, this.ClientCertificates, SslProtocols.Default, false);
1164                         stream = sslStream.AuthenticatedStream;
1165
1166 #else
1167                         throw new SystemException ("You are using an incomplete System.dll build");
1168 #endif
1169                 }
1170
1171                 void Authenticate ()
1172                 {
1173                         string user = null, pass = null;
1174
1175                         if (UseDefaultCredentials) {
1176                                 user = CredentialCache.DefaultCredentials.GetCredential (new System.Uri ("smtp://" + host), "basic").UserName;
1177                                 pass =  CredentialCache.DefaultCredentials.GetCredential (new System.Uri ("smtp://" + host), "basic").Password;
1178                         } else if (Credentials != null) {
1179                                 user = Credentials.GetCredential (host, port, "smtp").UserName;
1180                                 pass = Credentials.GetCredential (host, port, "smtp").Password;
1181                         } else {
1182                                 return;
1183                         }
1184
1185                         Authenticate (user, pass);
1186                 }
1187
1188                 void CheckStatus (SmtpResponse status, int i)
1189                 {
1190                         if (((int) status.StatusCode) != i)
1191                                 throw new SmtpException (status.StatusCode, status.Description);
1192                 }
1193
1194                 void ThrowIfError (SmtpResponse status)
1195                 {
1196                         if (IsError (status))
1197                                 throw new SmtpException (status.StatusCode, status.Description);
1198                 }
1199
1200                 void Authenticate (string user, string password)
1201                 {
1202                         if (authMechs == AuthMechs.None)
1203                                 return;
1204
1205                         SmtpResponse status;
1206                         /*
1207                         if ((authMechs & AuthMechs.DigestMD5) != 0) {
1208                                 status = SendCommand ("AUTH DIGEST-MD5");
1209                                 CheckStatus (status, 334);
1210                                 string challenge = Encoding.ASCII.GetString (Convert.FromBase64String (status.Description.Substring (4)));
1211                                 Console.WriteLine ("CHALLENGE: {0}", challenge);
1212                                 DigestSession session = new DigestSession ();
1213                                 session.Parse (false, challenge);
1214                                 string response = session.Authenticate (this, user, password);
1215                                 status = SendCommand (Convert.ToBase64String (Encoding.UTF8.GetBytes (response)));
1216                                 CheckStatus (status, 235);
1217                         } else */
1218                         if ((authMechs & AuthMechs.Login) != 0) {
1219                                 status = SendCommand ("AUTH LOGIN");
1220                                 CheckStatus (status, 334);
1221                                 status = SendCommand (Convert.ToBase64String (Encoding.UTF8.GetBytes (user)));
1222                                 CheckStatus (status, 334);
1223                                 status = SendCommand (Convert.ToBase64String (Encoding.UTF8.GetBytes (password)));
1224                                 CheckStatus (status, 235);
1225                         } else if ((authMechs & AuthMechs.Plain) != 0) {
1226                                 string s = String.Format ("\0{0}\0{1}", user, password);
1227                                 s = Convert.ToBase64String (Encoding.UTF8.GetBytes (s));
1228                                 status = SendCommand ("AUTH PLAIN " + s);
1229                                 CheckStatus (status, 235);
1230                         } else {
1231                                 throw new SmtpException ("AUTH types PLAIN, LOGIN not supported by the server");
1232                         }
1233                 }
1234
1235                 #endregion // Methods
1236
1237                 // The HeaderName struct is used to store constant string values representing mail headers.
1238                 private struct HeaderName {
1239                         public const string ContentTransferEncoding = "Content-Transfer-Encoding";
1240                         public const string ContentType = "Content-Type";
1241                         public const string Bcc = "Bcc";
1242                         public const string Cc = "Cc";
1243                         public const string From = "From";
1244                         public const string Subject = "Subject";
1245                         public const string To = "To";
1246                         public const string MimeVersion = "MIME-Version";
1247                         public const string MessageId = "Message-ID";
1248                         public const string Priority = "Priority";
1249                         public const string Importance = "Importance";
1250                         public const string XPriority = "X-Priority";
1251                         public const string Date = "Date";
1252                 }
1253
1254                 // This object encapsulates the status code and description of an SMTP response.
1255                 private struct SmtpResponse {
1256                         public SmtpStatusCode StatusCode;
1257                         public string Description;
1258
1259                         public static SmtpResponse Parse (string line) {
1260                                 SmtpResponse response = new SmtpResponse ();
1261
1262                                 if (line.Length < 4)
1263                                         throw new SmtpException ("Response is to short " +
1264                                                                  line.Length + ".");
1265
1266                                 if ((line [3] != ' ') && (line [3] != '-'))
1267                                         throw new SmtpException ("Response format is wrong.(" +
1268                                                                  line + ")");
1269
1270                                 // parse the response code
1271                                 response.StatusCode = (SmtpStatusCode) Int32.Parse (line.Substring (0, 3));
1272
1273                                 // set the raw response
1274                                 response.Description = line;
1275
1276                                 return response;
1277                         }
1278                 }
1279         }
1280
1281         class CCredentialsByHost : ICredentialsByHost
1282         {
1283                 public CCredentialsByHost (string userName, string password) {
1284                         this.userName = userName;
1285                         this.password = password;
1286                 }
1287
1288                 public NetworkCredential GetCredential (string host, int port, string authenticationType) {
1289                         return new NetworkCredential (userName, password);
1290                 }
1291
1292                 private string userName;
1293                 private string password;
1294         }
1295 }
1296