/// <summary>
/// Start a POP3 proxy instance.
/// </summary>
/// <param name="acceptedIPs">IP addresses to accept connections from.</param>
/// <param name="localIPAddress">Local IP address to bind to.</param>
/// <param name="localPort">Local port to listen on.</param>
/// <param name="localEnableSsl">Whether the local server supports TLS/SSL.</param>
/// <param name="remoteServerHostName">Remote server hostname to forward all POP3 messages to.</param>
/// <param name="remoteServerPort">Remote server port to connect to.</param>
/// <param name="remoteServerEnableSsl">Whether the remote POP3 server requires TLS/SSL.</param>
/// <param name="remoteServerCredential">(Optional) Credentials to be used for all connections to the remote POP3 server. When set, this overrides any credentials passed locally.</param>
/// <param name="exportDirectory">(Optional) Location where all incoming messages are saved as EML files.</param>
/// <param name="logFile">File where event logs and exception information will be written.</param>
/// <param name="logLevel">Proxy logging level, determining how much information is logged.</param>
/// <param name="instanceId">The instance number of the proxy.</param>
/// <param name="debugMode">Whether the proxy instance is running in DEBUG mode and should output full exception messages.</param>
public void Start(string acceptedIPs, IPAddress localIPAddress, int localPort, bool localEnableSsl, string remoteServerHostName, int remoteServerPort, bool remoteServerEnableSsl, NetworkCredential remoteServerCredential, string exportDirectory, string logFile, LogLevel logLevel, int instanceId, bool debugMode)
{
// Create the log writer.
string logFileName = "";
if (!string.IsNullOrEmpty(logFile))
{
logFileName = ProxyFunctions.GetLogFileName(logFile, instanceId, localIPAddress.ToString(), remoteServerHostName, localPort, remoteServerPort);
LogWriter = new StreamWriter(logFileName, true, Encoding.UTF8, Constants.SMALLBUFFERSIZE);
LogWriter.AutoFlush = true;
LogLevel = logLevel;
}
// Make sure the remote server isn't an infinite loop back to this server.
string fqdn = Functions.GetLocalFQDN();
if (remoteServerHostName.ToUpper() == fqdn.ToUpper() && remoteServerPort == localPort)
{
ProxyFunctions.Log(LogWriter, SessionId, "Cannot start service because the remote server host name {" + remoteServerHostName + "} and port {" + remoteServerPort.ToString() + "} is the same as this proxy, which would cause an infinite loop.", Proxy.LogLevel.Critical, LogLevel);
return;
}
IPHostEntry hostEntry = Dns.GetHostEntry(Dns.GetHostName());
foreach (IPAddress hostIP in hostEntry.AddressList)
{
if (remoteServerHostName == hostIP.ToString() && remoteServerPort == localPort)
{
ProxyFunctions.Log(LogWriter, SessionId, "Cannot start service because the remote server hostname {" + remoteServerHostName + "} and port {" + remoteServerPort.ToString() + "} is the same as this proxy, which would cause an infinite loop.", Proxy.LogLevel.Critical, LogLevel);
return;
}
}
ProxyFunctions.Log(LogWriter, SessionId, "Starting service.", Proxy.LogLevel.Information, LogLevel);
// Attempt to start up to 3 times in case another service using the port is shutting down.
int startAttempts = 0;
while (startAttempts < 3)
{
startAttempts++;
// If we've failed to start once, wait an extra 10 seconds.
if (startAttempts > 1)
{
ProxyFunctions.Log(LogWriter, SessionId, "Attempting to start for the " + (startAttempts == 2 ? "2nd" : "3rd") + " time.", Proxy.LogLevel.Information, LogLevel);
Thread.Sleep(10000 * startAttempts);
}
try
{
X509Certificate serverCertificate = null;
// Generate a unique session ID for logging.
SessionId = Guid.NewGuid().ToString();
ConnectionId = 0;
// If local SSL is supported via STARTTLS, ensure we have a valid server certificate.
if (localEnableSsl)
{
serverCertificate = CertHelper.GetCertificateBySubjectName(StoreLocation.LocalMachine, fqdn);
// In case the service as running as the current user, check the Current User certificate store as well.
if (serverCertificate == null)
{
serverCertificate = CertHelper.GetCertificateBySubjectName(StoreLocation.CurrentUser, fqdn);
}
// If no certificate was found, generate a self-signed certificate.
if (serverCertificate == null)
{
ProxyFunctions.Log(LogWriter, SessionId, "No signing certificate found, so generating new certificate.", Proxy.LogLevel.Warning, LogLevel);
List <string> oids = new List <string>();
oids.Add("1.3.6.1.5.5.7.3.1"); // Server Authentication.
// Generate the certificate with a duration of 10 years, 4096-bits, and a key usage of server authentication.
serverCertificate = CertHelper.CreateSelfSignedCertificate(fqdn, fqdn, StoreLocation.LocalMachine, true, 4096, 10, oids);
ProxyFunctions.Log(LogWriter, SessionId, "Certificate generated with Serial Number {" + serverCertificate.GetSerialNumberString() + "}.", Proxy.LogLevel.Information, LogLevel);
}
}
// Start listening on the specified port and IP address.
Listener = new TcpListener(localIPAddress, localPort);
Listener.Start();
ProxyFunctions.Log(LogWriter, SessionId, "Service started.", Proxy.LogLevel.Information, LogLevel);
ProxyFunctions.Log(LogWriter, SessionId, "Listening on address {" + localIPAddress.ToString() + "}, port {" + localPort + "}.", Proxy.LogLevel.Information, LogLevel);
Started = true;
// Accept client requests, forking each into its own thread.
while (Started)
{
TcpClient client = Listener.AcceptTcpClient();
string newLogFileName = ProxyFunctions.GetLogFileName(logFile, instanceId, localIPAddress.ToString(), remoteServerHostName, localPort, remoteServerPort);
if (newLogFileName != logFileName)
{
if (LogWriter != null)
{
LogWriter.Close();
}
LogWriter = new StreamWriter(newLogFileName, true, Encoding.UTF8, Constants.SMALLBUFFERSIZE);
LogWriter.AutoFlush = true;
}
// Prepare the arguments for our new thread.
Pop3ProxyConnectionArguments arguments = new Pop3ProxyConnectionArguments();
arguments.AcceptedIPs = acceptedIPs;
arguments.TcpClient = client;
arguments.Certificate = serverCertificate;
arguments.ExportDirectory = exportDirectory;
arguments.LocalIpAddress = localIPAddress;
arguments.LocalPort = localPort;
arguments.LocalEnableSsl = localEnableSsl;
arguments.RemoteServerHostName = remoteServerHostName;
arguments.RemoteServerPort = remoteServerPort;
arguments.RemoteServerEnableSsl = remoteServerEnableSsl;
arguments.RemoteServerCredential = remoteServerCredential;
// Increment the connection counter;
arguments.ConnectionId = (unchecked (++ConnectionId)).ToString();
arguments.InstanceId = instanceId;
arguments.DebugMode = debugMode;
// Fork the thread and continue listening for new connections.
Thread processThread = new Thread(new ParameterizedThreadStart(ProcessConnection));
processThread.Name = "OpaqueMail POP3 Proxy Connection";
processThread.Start(arguments);
}
return;
}
catch (Exception ex)
{
if (debugMode || System.Diagnostics.Debugger.IsAttached)
{
ProxyFunctions.Log(LogWriter, SessionId, "Exception when starting proxy: " + ex.ToString(), Proxy.LogLevel.Critical, LogLevel);
}
else
{
ProxyFunctions.Log(LogWriter, SessionId, "Exception when starting proxy: " + ex.Message, Proxy.LogLevel.Critical, LogLevel);
}
}
}
}
