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fixing typos
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@RobHolme
RobHolme committed Sep 22, 2022
1 parent bc201b6 commit 3a0bca8
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Showing 2 changed files with 137 additions and 32 deletions.
163 changes: 134 additions & 29 deletions src/HL7TCPListener.cs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
// Rob Holme ([email protected])
// 03/06/2015 - Initial version
// 01/09/2016 - Changed behaviour to always send ACKS (unless -NoACK is set). No longer honouring the ACK mode from MSH-15, this caused issues for senders epecting ACKS but not setting MSH-15.
// 01/09/2016 - Changed behaviour to always send ACKS (unless -NoACK is set). No longer honouring the ACK mode from MSH-15, this caused issues for senders expecting ACKS but not setting MSH-15.

namespace HL7ListenerApplication {
using System;
Expand Down Expand Up @@ -97,8 +97,8 @@ public bool Start() {
// create a thread to send messages to the Passsthru host
this.passthruThread = new Thread(new ThreadStart(SendData));
passthruThread.Start();
// create a thread to recieve the ACKs from the passthru host
this.passthruAckThread = new Thread(new ThreadStart(ReceieveACK));
// create a thread to receive the ACKs from the passthru host
this.passthruAckThread = new Thread(new ThreadStart(ReceiveACK));
passthruAckThread.Start();
LogInformation("Connected to PassThru host");
}
Expand All @@ -118,19 +118,19 @@ public void RequestStop() {
/// </summary>
private void StartListener() {
try {
X509Certificate2 cert;
this.tcpListener.Start();
// run the thread unless a request to stop is received
while (this.runThread) {
if (this.tlsRequired) {
cert = new X509Certificate2(this.tlsCertificatePath);
// cert = new X509Certificate2(this.tlsCertificatePath);
TcpClient client = this.tcpListener.AcceptTcpClient();
this.LogInformation("New client connection accepted from " + client.Client.RemoteEndPoint);
SslStream sslStream = new SslStream(client.GetStream());
sslStream.AuthenticateAsServer(cert);
Thread clientThread = new Thread(new ParameterizedThreadStart(ReceiveData));
clientThread.Start(sslStream);
cert.Dispose();
// SslStream sslStream = new SslStream(client.GetStream());
// sslStream.AuthenticateAsServer(cert);
Thread clientThread = new Thread(new ParameterizedThreadStart(ReceiveTLSData));
clientThread.Start(client);
// cert.Dispose();
// client.Close();
}
else {
// waits for a client connection to the listener
Expand All @@ -143,12 +143,6 @@ private void StartListener() {

}
}
catch (System.Security.Cryptography.CryptographicException e) {
LogWarning("An error occurred while attempting import the PFX certificate " + this.tlsCertificatePath);
LogWarning("Make sure the certificate is if PFX format and does not require a password.");
LogWarning(e.Message);
LogWarning("HL7Listener exiting.");
}
catch (Exception e) {
LogWarning("An error occurred while attempting to start the listener on port " + this.listenerPort);
LogWarning(e.Message);
Expand Down Expand Up @@ -206,7 +200,7 @@ private void ReceiveData(object client) {
if (passthruHost != null) {
messageQueue.Enqueue(messageData.Substring(start + 1, end - (start + 1)));
}
// create a HL7message object from the message recieved. Use this to access elements needed to populate the ACK message and file name of the archived message
// create a HL7message object from the message received. Use this to access elements needed to populate the ACK message and file name of the archived message
HL7Message message = new HL7Message(messageData.Substring(start + 1, end - (start + 1)));
messageData = ""; // reset the message data string for the next message
string messageTrigger = message.GetMessageTrigger();
Expand All @@ -216,7 +210,7 @@ private void ReceiveData(object client) {
string filename = dateStamp + "_" + (filenameSequenceStart + messageCount).ToString("D6") + "_" + messageTrigger + ".hl7"; // increment sequence number for each filename
// Write the HL7 message to file.
WriteMessageToFile(message.ToString(), this.archivePath + filename);
// send ACK message is MSH-15 is set to AL and ACKs not disbaled by -NOACK command line switch
// send ACK message is MSH-15 is set to AL and ACKs not disabled by -NOACK command line switch
//if ((this.sendACK) && (acceptAckType.ToUpper() == "AL"))
if (this.sendACK) {
LogInformation("Sending ACK (Message Control ID: " + messageControlID + ")");
Expand Down Expand Up @@ -251,6 +245,117 @@ private void ReceiveData(object client) {
tcpClient.Close();
}

/// <summary>
/// Receive data from a TLS client connection, look for MLLP HL7 message.
/// </summary>
/// <param name="client"></param>
private void ReceiveTLSData(object client) {
// generate a random sequence number to use for the file names
Random random = new Random(Guid.NewGuid().GetHashCode());
int filenameSequenceStart = random.Next(0, 1000000);

try {
X509Certificate2 cert = new X509Certificate2(this.tlsCertificatePath);
TcpClient tcpClient = (TcpClient)client;
SslStream clientStream = new SslStream(tcpClient.GetStream());
clientStream.ReadTimeout = TCP_TIMEOUT;
clientStream.WriteTimeout = TCP_TIMEOUT;
clientStream.AuthenticateAsServer(cert);


byte[] messageBuffer = new byte[4096];
int bytesRead;
String messageData = "";
int messageCount = 0;

while (true) {
bytesRead = 0;
try {
// Wait until a client application submits a message
bytesRead = clientStream.Read(messageBuffer, 0, 4096);
}
catch {
// A network error has occurred
LogInformation("Connection from " + tcpClient.Client.RemoteEndPoint + " has ended");
break;
}
if (bytesRead == 0) {
// The client has disconnected
LogInformation("The client " + tcpClient.Client.RemoteEndPoint + " has disconnected");
break;
}
// Message buffer received successfully
messageData += encoder.GetString(messageBuffer, 0, bytesRead);
// Find a VT character, this is the beginning of the MLLP frame
int start = messageData.IndexOf((char)0x0B);
if (start >= 0) {
// Search for the end of the MLLP frame (a FS character)
int end = messageData.IndexOf((char)0x1C);
if (end > start) {
messageCount++;
try {
// queue the message to sent to the passthru host if the -PassThru option has been set
if (passthruHost != null) {
messageQueue.Enqueue(messageData.Substring(start + 1, end - (start + 1)));
}
// create a HL7message object from the message received. Use this to access elements needed to populate the ACK message and file name of the archived message
HL7Message message = new HL7Message(messageData.Substring(start + 1, end - (start + 1)));
messageData = ""; // reset the message data string for the next message
string messageTrigger = message.GetMessageTrigger();
string messageControlID = message.GetHL7Item("MSH-10")[0];
//string acceptAckType = message.GetHL7Item("MSH-15")[0];
string dateStamp = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString().PadLeft(2, '0') + DateTime.Now.Day.ToString().PadLeft(2, '0') + DateTime.Now.Hour.ToString().PadLeft(2, '0') + DateTime.Now.Minute.ToString().PadLeft(2, '0');
string filename = dateStamp + "_" + (filenameSequenceStart + messageCount).ToString("D6") + "_" + messageTrigger + ".hl7"; // increment sequence number for each filename
// Write the HL7 message to file.
WriteMessageToFile(message.ToString(), this.archivePath + filename);
// send ACK message is MSH-15 is set to AL and ACKs not disabled by -NOACK command line switch
//if ((this.sendACK) && (acceptAckType.ToUpper() == "AL"))
if (this.sendACK) {
LogInformation("Sending ACK (Message Control ID: " + messageControlID + ")");
// generate ACK Message and send in response to the message received
string response = GenerateACK(message.ToString()); // TO DO: send ACKS if set in message header, or specified on command line
byte[] encodedResponse = encoder.GetBytes(response);
// Send response
try {
clientStream.Write(encodedResponse, 0, encodedResponse.Length);
clientStream.Flush();
}
catch (Exception e) {
// A network error has occurred
LogInformation("An error has occurred while sending an ACK to the client " + tcpClient.Client.RemoteEndPoint);
LogInformation(e.Message);
LogInformation(e.InnerException.ToString());
break;
}
}
}
catch (Exception e) {
messageData = ""; // reset the message data string for the next message
LogWarning("An exception occurred while parsing the HL7 message");
LogWarning(e.Message);
break;
}
}
}
}
LogInformation("Total messages received:" + messageCount);
clientStream.Close();
clientStream.Dispose();
tcpClient.Close();
tcpClient.Dispose();
cert.Dispose();
}
catch (System.Security.Cryptography.CryptographicException e) {
LogWarning("An error occurred while attempting import the PFX certificate " + this.tlsCertificatePath);
LogWarning("Make sure the certificate is in PFX format and does not require a password.");
LogWarning(e.Message);
}
catch (Exception e) {
LogWarning("An error occurred while attempting to negotiate TLS.");
LogWarning(e.Message);
}
}


/// <summary>
/// Send the HL7 message to the remote host in a MLLP frame
Expand All @@ -265,7 +370,7 @@ private void SendData() {

while (this.runThread) {
while (messageQueue.TryDequeue(out tempMessage)) {
// generate a MLLP framed messsage
// generate a MLLP framed message
StringBuilder messageString = new StringBuilder();
messageString.Append((char)0x0B);
messageString.Append(tempMessage);
Expand All @@ -275,9 +380,9 @@ private void SendData() {
try {
// encode and send the message
byte[] buffer = encoder.GetBytes(messageString.ToString());
// if the client connection has timed out, or the remote host has disconected, reconnect.
// if the client connection has timed out, or the remote host has disconnected, reconnect.
if (!this.PassthruClientStream.CanWrite) {
LogInformation("Connection to passthru host has closed. Reconecting to " + this.passthruHost + ":" + this.passthruPort);
LogInformation("Connection to passthru host has closed. Reconnecting to " + this.passthruHost + ":" + this.passthruPort);
this.passthruClient.Close();
this.passthruClient = new TcpClient();
this.remoteEndpoint = new IPEndPoint(IPAddress.Parse(this.PassthruHost), this.passthruPort);
Expand All @@ -291,7 +396,7 @@ private void SendData() {
this.PassthruClientStream.Flush();
}
catch (Exception e) {
LogWarning("Unable to send messsage to -Passsthru host (" + this.PassthruHost + ":" + this.passthruPort + ")");
LogWarning("Unable to send message to -Passsthru host (" + this.PassthruHost + ":" + this.passthruPort + ")");
LogWarning(e.Message);
}
}
Expand All @@ -301,7 +406,7 @@ private void SendData() {

/// <summary>
/// /// <summary>
/// Write the HL7 message recieved to file. Optionally provide the file path, otherwise use the working directory.
/// Write the HL7 message received to file. Optionally provide the file path, otherwise use the working directory.
/// </summary>
/// <param name="message"></param>
/// <param name="filePath"></param>
Expand Down Expand Up @@ -349,13 +454,13 @@ string GenerateACK(string originalMessage) {
/// Recieve ACKs from the PassThru host.
/// Run this in a thread as this will block execution waiting for a response.
/// </summary>
private void ReceieveACK() {
private void ReceiveACK() {
int bytesRead;
string ackData = "";
byte[] receiveBuffer = new byte[4096];

// wait for the ACK to be returned, or a timeout occurrs. Do nothing with the ACK recived (discard).
LogInformation("Recieve ACK thread started");
// wait for the ACK to be returned, or a timeout occurs. Do nothing with the ACK received (discard).
LogInformation("Receive ACK thread started");
while (this.runThread) {
try {
bytesRead = this.PassthruClientStream.Read(receiveBuffer, 0, 4096);
Expand All @@ -373,14 +478,14 @@ private void ReceieveACK() {
}
}
catch (Exception) {
LogWarning("Connecion timed out or ended while waiting for ACK from PassThru host.");
LogWarning("Connection timed out or ended while waiting for ACK from PassThru host.");
break;
}
}
}

/// <summary>
/// Set and get the values of the SendACK option. This can be used to overide sending of ACK messages.
/// Set and get the values of the SendACK option. This can be used to override sending of ACK messages.
/// </summary>
public bool SendACK {
get { return this.sendACK; }
Expand All @@ -398,7 +503,7 @@ public string PassthruHost {


/// <summary>
/// The PassthruPort property identies the remote port to pass the messages thought to.
/// The PassthruPort property identifies the remote port to pass the messages thought to.
/// </summary>
public int PassthruPort {
set { this.passthruPort = value; }
Expand Down
6 changes: 3 additions & 3 deletions src/Program.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ class Program {
static void Main(string[] args) {
// parse command line arguments
if (ParseArgs(args)) {
// create a new instance of HL7TCPListener. Set optional properties to rturn ACKs, passthru messages, archive locaiton. Start the listener.
// create a new instance of HL7TCPListener. Set optional properties to return ACKs, passthru messages, archive location. Start the listener.
HL7TCPListener listener = new HL7TCPListener(port, encoding, useTLS);
listener.SendACK = sendACK;
if (filePath != null) {
Expand All @@ -41,7 +41,7 @@ static void Main(string[] args) {


/// <summary>
/// Parse the command line arguements
/// Parse the command line arguments
/// </summary>
/// <param name="args"></param>
static bool ParseArgs(string[] cmdArgs) {
Expand All @@ -65,7 +65,7 @@ static bool ParseArgs(string[] cmdArgs) {
LogWarning("The port number provided needs to be an integer between 1025 and 65535");
return false;
}
// validate the port entered is witin the correct range.
// validate the port entered is within the correct range.
if ((port < 1025) || (port > 65535)) {
LogWarning("The port number must be an integer between 1025 and 65535");
return false;
Expand Down

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