/// <summary>
/// Establishes a connection to the specified SMTP or SMTP/S server.
/// </summary>
/// <remarks>
/// <para>Establishes a connection to the specified SMTP or SMTP/S server.</para>
/// <para>If the <paramref name="port"/> has a value of <c>0</c>, then the
/// <paramref name="options"/> parameter is used to determine the default port to
/// connect to. The default port used with <see cref="SecureSocketOptions.SslOnConnect"/>
/// is <c>465</c>. All other values will use a default port of <c>25</c>.</para>
/// <para>If the <paramref name="options"/> has a value of
/// <see cref="SecureSocketOptions.Auto"/>, then the <paramref name="port"/> is used
/// to determine the default security options. If the <paramref name="port"/> has a value
/// of <c>465</c>, then the default options used will be
/// <see cref="SecureSocketOptions.SslOnConnect"/>. All other values will use
/// <see cref="SecureSocketOptions.StartTlsWhenAvailable"/>.</para>
/// <para>Once a connection is established, properties such as
/// <see cref="AuthenticationMechanisms"/> and <see cref="Capabilities"/> will be
/// populated.</para>
/// <para>Note: The connection established by any of the
/// <a href="Overload_MailKit_Net_Smtp_SmtpClient_Connect.htm">Connect</a>
/// methods may be re-used if an application wishes to send multiple messages
/// to the same SMTP server. Since connecting and authenticating can be expensive
/// operations, re-using a connection can significantly improve performance when
/// sending a large number of messages to the same SMTP server over a short
/// period of time.</para>
/// </remarks>
/// <example>
/// <code language="c#" source="Examples\SmtpExamples.cs" region="SendMessage"/>
/// </example>
/// <param name="host">The host name to connect to.</param>
/// <param name="port">The port to connect to. If the specified port is <c>0</c>, then the default port will be used.</param>
/// <param name="options">The secure socket options to when connecting.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <exception cref="System.ArgumentNullException">
/// <paramref name="host"/> is <c>null</c>.
/// </exception>
/// <exception cref="System.ArgumentOutOfRangeException">
/// <paramref name="port"/> is not between <c>0</c> and <c>65535</c>.
/// </exception>
/// <exception cref="System.ArgumentException">
/// The <paramref name="host"/> is a zero-length string.
/// </exception>
/// <exception cref="System.ObjectDisposedException">
/// The <see cref="SmtpClient"/> has been disposed.
/// </exception>
/// <exception cref="System.InvalidOperationException">
/// The <see cref="SmtpClient"/> is already connected.
/// </exception>
/// <exception cref="System.NotSupportedException">
/// <paramref name="options"/> was set to
/// <see cref="MailKit.Security.SecureSocketOptions.StartTls"/>
/// and the SMTP server does not support the STARTTLS extension.
/// </exception>
/// <exception cref="System.OperationCanceledException">
/// The operation was canceled.
/// </exception>
/// <exception cref="System.IO.IOException">
/// An I/O error occurred.
/// </exception>
/// <exception cref="SmtpCommandException">
/// An SMTP command failed.
/// </exception>
/// <exception cref="SmtpProtocolException">
/// An SMTP protocol error occurred.
/// </exception>
public override void Connect (string host, int port = 0, SecureSocketOptions options = SecureSocketOptions.Auto, CancellationToken cancellationToken = default (CancellationToken))
{
if (host == null)
throw new ArgumentNullException ("host");
if (host.Length == 0)
throw new ArgumentException ("The host name cannot be empty.", "host");
if (port < 0 || port > 65535)
throw new ArgumentOutOfRangeException ("port");
CheckDisposed ();
if (IsConnected)
throw new InvalidOperationException ("The SmtpClient is already connected.");
capabilities = SmtpCapabilities.None;
AuthenticationMechanisms.Clear ();
MaxSize = 0;
SmtpResponse response;
Stream stream;
bool starttls;
Uri uri;
ComputeDefaultValues (host, ref port, ref options, out uri, out starttls);
#if !NETFX_CORE
var ipAddresses = Dns.GetHostAddresses (host);
Socket socket = null;
for (int i = 0; i < ipAddresses.Length; i++) {
socket = new Socket (ipAddresses[i].AddressFamily, SocketType.Stream, ProtocolType.Tcp);
try {
cancellationToken.ThrowIfCancellationRequested ();
if (LocalEndPoint != null)
socket.Bind (LocalEndPoint);
socket.Connect (ipAddresses[i], port);
break;
} catch (OperationCanceledException) {
socket.Dispose ();
socket = null;
throw;
} catch {
socket.Dispose ();
socket = null;
if (i + 1 == ipAddresses.Length)
throw;
}
}
if (socket == null)
throw new IOException (string.Format ("Failed to resolve host: {0}", host));
this.host = host;
if (options == SecureSocketOptions.SslOnConnect) {
var ssl = new SslStream (new NetworkStream (socket, true), false, ValidateRemoteCertificate);
ssl.AuthenticateAsClient (host, ClientCertificates, SslProtocols, true);
stream = ssl;
} else {
stream = new NetworkStream (socket, true);
}
#else
var protection = options == SecureSocketOptions.SslOnConnect ? SocketProtectionLevel.Tls12 : SocketProtectionLevel.PlainSocket;
var socket = new StreamSocket ();
try {
cancellationToken.ThrowIfCancellationRequested ();
socket.ConnectAsync (new HostName (host), port.ToString (), protection)
.AsTask (cancellationToken)
.GetAwaiter ()
.GetResult ();
} catch {
socket.Dispose ();
throw;
}
stream = new DuplexStream (socket.InputStream.AsStreamForRead (0), socket.OutputStream.AsStreamForWrite (0));
#endif
if (stream.CanTimeout) {
stream.WriteTimeout = timeout;
stream.ReadTimeout = timeout;
}
ProtocolLogger.LogConnect (uri);
Stream = new SmtpStream (stream, socket, ProtocolLogger);
try {
// read the greeting
response = Stream.ReadResponse (cancellationToken);
if (response.StatusCode != SmtpStatusCode.ServiceReady)
throw new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response);
// Send EHLO and get a list of supported extensions
Ehlo (cancellationToken);
if (options == SecureSocketOptions.StartTls && (capabilities & SmtpCapabilities.StartTLS) == 0)
throw new NotSupportedException ("The SMTP server does not support the STARTTLS extension.");
if (starttls && (capabilities & SmtpCapabilities.StartTLS) != 0) {
response = SendCommand ("STARTTLS", cancellationToken);
if (response.StatusCode != SmtpStatusCode.ServiceReady)
throw new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response);
#if !NETFX_CORE
var tls = new SslStream (stream, false, ValidateRemoteCertificate);
tls.AuthenticateAsClient (host, ClientCertificates, SslProtocols, true);
Stream.Stream = tls;
#else
socket.UpgradeToSslAsync (SocketProtectionLevel.Tls12, new HostName (host))
.AsTask (cancellationToken)
.GetAwaiter ()
.GetResult ();
#endif
// Send EHLO again and get the new list of supported extensions
Ehlo (cancellationToken);
}
connected = true;
} catch {
Stream.Dispose ();
Stream = null;
throw;
}
OnConnected ();
}
/// <summary>
/// Establish a connection to the specified SMTP or SMTP/S server using the provided socket.
/// </summary>
/// <remarks>
/// <para>Establishes a connection to the specified SMTP or SMTP/S server.</para>
/// <para>If the <paramref name="port"/> has a value of <c>0</c>, then the
/// <paramref name="options"/> parameter is used to determine the default port to
/// connect to. The default port used with <see cref="SecureSocketOptions.SslOnConnect"/>
/// is <c>465</c>. All other values will use a default port of <c>25</c>.</para>
/// <para>If the <paramref name="options"/> has a value of
/// <see cref="SecureSocketOptions.Auto"/>, then the <paramref name="port"/> is used
/// to determine the default security options. If the <paramref name="port"/> has a value
/// of <c>465</c>, then the default options used will be
/// <see cref="SecureSocketOptions.SslOnConnect"/>. All other values will use
/// <see cref="SecureSocketOptions.StartTlsWhenAvailable"/>.</para>
/// <para>Once a connection is established, properties such as
/// <see cref="AuthenticationMechanisms"/> and <see cref="Capabilities"/> will be
/// populated.</para>
/// <para>Note: The connection established by any of the
/// <a href="Overload_MailKit_Net_Smtp_SmtpClient_Connect.htm">Connect</a>
/// methods may be re-used if an application wishes to send multiple messages
/// to the same SMTP server. Since connecting and authenticating can be expensive
/// operations, re-using a connection can significantly improve performance when
/// sending a large number of messages to the same SMTP server over a short
/// period of time.</para>
/// </remarks>
/// <param name="socket">The socket to use for the connection.</param>
/// <param name="host">The host name to connect to.</param>
/// <param name="port">The port to connect to. If the specified port is <c>0</c>, then the default port will be used.</param>
/// <param name="options">The secure socket options to when connecting.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <exception cref="System.ArgumentNullException">
/// <para><paramref name="socket"/> is <c>null</c>.</para>
/// <para>-or-</para>
/// <para><paramref name="host"/> is <c>null</c>.</para>
/// </exception>
/// <exception cref="System.ArgumentOutOfRangeException">
/// <paramref name="port"/> is not between <c>0</c> and <c>65535</c>.
/// </exception>
/// <exception cref="System.ArgumentException">
/// <para><paramref name="socket"/> is not connected.</para>
/// <para>-or-</para>
/// The <paramref name="host"/> is a zero-length string.
/// </exception>
/// <exception cref="System.ObjectDisposedException">
/// The <see cref="SmtpClient"/> has been disposed.
/// </exception>
/// <exception cref="System.InvalidOperationException">
/// The <see cref="SmtpClient"/> is already connected.
/// </exception>
/// <exception cref="System.NotSupportedException">
/// <paramref name="options"/> was set to
/// <see cref="MailKit.Security.SecureSocketOptions.StartTls"/>
/// and the SMTP server does not support the STARTTLS extension.
/// </exception>
/// <exception cref="System.OperationCanceledException">
/// The operation was canceled.
/// </exception>
/// <exception cref="System.IO.IOException">
/// An I/O error occurred.
/// </exception>
/// <exception cref="SmtpCommandException">
/// An SMTP command failed.
/// </exception>
/// <exception cref="SmtpProtocolException">
/// An SMTP protocol error occurred.
/// </exception>
public void Connect (Socket socket, string host, int port = 0, SecureSocketOptions options = SecureSocketOptions.Auto, CancellationToken cancellationToken = default (CancellationToken))
{
if (socket == null)
throw new ArgumentNullException ("socket");
if (!socket.Connected)
throw new ArgumentException ("The socket is not connected.", "socket");
if (host == null)
throw new ArgumentNullException ("host");
if (host.Length == 0)
throw new ArgumentException ("The host name cannot be empty.", "host");
if (port < 0 || port > 65535)
throw new ArgumentOutOfRangeException ("port");
CheckDisposed ();
if (IsConnected)
throw new InvalidOperationException ("The SmtpClient is already connected.");
capabilities = SmtpCapabilities.None;
AuthenticationMechanisms.Clear ();
MaxSize = 0;
SmtpResponse response;
Stream stream;
bool starttls;
Uri uri;
ComputeDefaultValues (host, ref port, ref options, out uri, out starttls);
this.host = host;
if (options == SecureSocketOptions.SslOnConnect) {
var ssl = new SslStream (new NetworkStream (socket, true), false, ValidateRemoteCertificate);
ssl.AuthenticateAsClient (host, ClientCertificates, SslProtocols, true);
stream = ssl;
} else {
stream = new NetworkStream (socket, true);
}
if (stream.CanTimeout) {
stream.WriteTimeout = timeout;
stream.ReadTimeout = timeout;
}
ProtocolLogger.LogConnect (uri);
Stream = new SmtpStream (stream, socket, ProtocolLogger);
try {
// read the greeting
response = Stream.ReadResponse (cancellationToken);
if (response.StatusCode != SmtpStatusCode.ServiceReady)
throw new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response);
// Send EHLO and get a list of supported extensions
Ehlo (cancellationToken);
if (options == SecureSocketOptions.StartTls && (capabilities & SmtpCapabilities.StartTLS) == 0)
throw new NotSupportedException ("The SMTP server does not support the STARTTLS extension.");
if (starttls && (capabilities & SmtpCapabilities.StartTLS) != 0) {
response = SendCommand ("STARTTLS", cancellationToken);
if (response.StatusCode != SmtpStatusCode.ServiceReady)
throw new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response);
var tls = new SslStream (stream, false, ValidateRemoteCertificate);
tls.AuthenticateAsClient (host, ClientCertificates, SslProtocols, true);
Stream.Stream = tls;
// Send EHLO again and get the new list of supported extensions
Ehlo (cancellationToken);
}
connected = true;
} catch {
Stream.Dispose ();
Stream = null;
throw;
}
OnConnected ();
}
internal void ReplayConnect (string hostName, Stream replayStream, CancellationToken cancellationToken = default (CancellationToken))
{
CheckDisposed ();
if (hostName == null)
throw new ArgumentNullException ("hostName");
if (replayStream == null)
throw new ArgumentNullException ("replayStream");
Stream = new SmtpStream (replayStream, null, ProtocolLogger);
capabilities = SmtpCapabilities.None;
AuthenticationMechanisms.Clear ();
host = hostName;
MaxSize = 0;
try {
// read the greeting
var response = Stream.ReadResponse (cancellationToken);
if (response.StatusCode != SmtpStatusCode.ServiceReady)
throw new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response);
// Send EHLO and get a list of supported extensions
Ehlo (cancellationToken);
connected = true;
} catch {
Stream.Dispose ();
Stream = null;
throw;
}
OnConnected ();
}
