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CavemanTcp

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1.0.0

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CavemanTcp

CavemanTcp gives you the ultimate control in building TCP-based applications involving clients and servers.

With CavemanTcp, you have full control over reading and writing data. CavemanTcp is designed for those that want explicit control over when data is read or written or want to build a state machine on top of TCP.

Important:

If you are looking for a package that will continually read data and raise events when data is received, see SimpleTcp: https://github.com/jchristn/simpletcp
If you are looking for an all-in-one package that handles delivery of well-formed application-layer messages, see WatsonTcp: https://github.com/jchristn/watsontcp

Disconnection Handling

Since CavemanTcp relies on the consuming application to specify when to read or write, there are no background threads continually monitoring the state of the TCP connection (unlike SimpleTcp and WatsonTcp). Thus, you should build your apps on the expectation that an exception may be thrown while in the middle of a read or write.

As of v1.3.0, TCP keepalive support was added for .NET Core and .NET Framework; unfortunately .NET Standard does not offer this support, so it is not present for apps using CavemanTcp targeted to .NET Standard.

New in v2.0.x

Breaking changes
Clients now referenced by Guid instead of string ipPort
ListClients now returns an enumeration of ClientMetadata
Send and Read methods using string ipPort are marked obsolete
AddClient moved closer to connection acceptance
Target net461 net472 net48 net6.0 net7.0 and net8.0
Better detection of disconnects
Disable Nagle's algorithm by default

Examples

Server Example

using CavemanTcp;

// Instantiate
TcpServer server = new TcpServer("127.0.0.1", 8000, false, null, null);
server.Logger = Logger;

// Set callbacks
server.Events.ClientConnected += (s, e) => 
{ 
    Console.WriteLine("Client " + e.Client.ToString() + " connected to server");
};
server.Events.ClientDisconnected += (s, e) => 
{ 
    Console.WriteLine("Client " + e.Client.ToString() + " disconnected from server"); 
}; 

// Start server
server.Start(); 

// Send [Data] to client at [guid] 
Guid guid = Guid.Parse("00001111-2222-3333-4444-555566667777");
WriteResult wr = null;
wr = server.Send(guid, "[Data]");
wr = server.SendWithTimeout([ms], guid, "[Data]");
wr = await server.SendAsync(guid, "[Data]");
wr = await server.SendWithTimeoutAsync([ms], guid, "[Data]");

// Receive [count] bytes of data from client at [guid]
ReadResult rr = null;
rr = server.Read(guid, [count]);
rr = server.ReadWithTimeout([ms], guid, count);
rr = await server.ReadAsync(guid, [count]);
rr = await server.ReadWithTimeoutAsync([ms], guid, [count]);

// List clients
List<ClientMetadata> clients = server.GetClients().ToList();

// Disconnect a client
server.DisconnectClient(guid);

Client Example

using CavemanTcp; 

// Instantiate
TcpClient client = new TcpClient("127.0.0.1", 8000, false, null, null);
client.Logger = Logger;

// Set callbacks
client.Events.ClientConnected += (s, e) => 
{ 
    Console.WriteLine("Connected to server"); 
};

client.Events.ClientDisconnected += (s, e) => 
{ 
    Console.WriteLine("Disconnected from server"); 
};

// Connect to server
client.Connect(10);

// Send data to server
WriteResult wr = null;
wr = client.Send("[Data]");
wr = client.SendWithTimeout([ms], "[Data]");
wr = await client.SendAsync("[Data]");
wr = await client.SendWithTimeoutAsync([ms], "[Data]");

// Read [count] bytes of data from server
ReadResult rr = null;
rr = client.Read([count]);
rr = client.ReadWithTimeout([ms], count);
rr = await client.ReadAsync([count]);
rr = await client.ReadWithTimeoutAsync([ms], [count]);

WriteResult and ReadResult

WriteResult and ReadResult contains a Status property that indicates one of the following:

ClientNotFound - only applicable for server read and write operations
Success - the operation was successful
Timeout - the operation timed out (reserved for future use)
Disconnected - the peer disconnected

WriteResult also includes:

BytesWritten - the number of bytes written to the socket.

ReadResult also includes:

BytesRead - the number of bytes read from the socket.
DataStream - a MemoryStream containing the requested data.
Data - a byte[] representation of DataStream. Using this property will fully read DataStream to the end.

Local vs External Connections

IMPORTANT

If you specify 127.0.0.1 as the listener IP address, it will only be able to accept connections from within the local host.
To accept connections from other machines:
- Use a specific interface IP address, or
- Use null, *, +, or 0.0.0.0 for the listener IP address (requires admin privileges to listen on any IP address)
Make sure you create a permit rule on your firewall to allow inbound connections on that port
If you use a port number under 1024, admin privileges will be required

Operations with Timeouts

When using any of the APIs that allow you to specify a timeout (i.e. SendWithTimeout, SendWithTimeoutAsync, ReadWithTimeout, and ReadWithTimeoutAsync), the resultant WriteResult and ReadResult as mentioned above will indicate if the operation timed out.

It is important to understand what a timeout indicates and more important what it doesn't.

A timeout on a write operation has nothing to do with whether or not the recipient read the data. Rather it is whether or not CavemanTcp was able to write the data to the underlying NetworkStream or SslStream
A timeout on a read operation will occur if CavemanTcp is unable to read the specified number of bytes from the underlying NetworkStream or SslStream in the allotted number of milliseconds
Valid values for timeoutMs are -1 or any positive integer. -1 indicates no timeout and is the same as using an API that doesn't specify a timeout
Pay close attention to either BytesRead or BytesWritten (if you were reading or writing) in the event of a timeout. The timeout may have occurred mid-operation and therefore it will be important to recover from the failure.
- For example, server sends client 50,000 bytes
- On the client, a ReadWithTimeout was initiated with a 10 second timeout, attempting to read 50,000 bytes
- In that 10 seconds, the client was only able to read 30,000 bytes
- A ReadResult with Status == ReadResultStatus.Timeout is returned, and the BytesRead property is set to 30,000
- In this case, there are still 20,000 bytes from the server waiting in the client's underlying NetworkStream or SslStream
- As such, it is recommended that, upon timeout, you reset the connection (but this is your choice)

TCP Keepalives

As of v1.3.0, support for TCP keepalives has been added to CavemanTcp, primarily to address the issue of a network interface being shut down, the cable unplugged, or the media otherwise becoming unavailable. It is important to note that keepalives are supported in .NET Core and .NET Framework, but NOT .NET Standard. As of this release, .NET Standard provides no facilities for TCP keepalives.

TCP keepalives are enabled by default.

server.Keepalive.EnableTcpKeepAlives = true;
server.Keepalive.TcpKeepAliveInterval = 5;      // seconds to wait before sending subsequent keepalive
server.Keepalive.TcpKeepAliveTime = 5;          // seconds to wait before sending a keepalive
server.Keepalive.TcpKeepAliveRetryCount = 5;    // number of failed keepalive probes before terminating connection

Some important notes about TCP keepalives:

This capability is enabled by the underlying framework and operating system, not provided by this library
Keepalives only work in .NET Core and .NET Framework
Keepalives can be enabled on either client or server, but generally only work on server (being investigated)
Keepalive.TcpKeepAliveRetryCount is only applicable to .NET Core; for .NET Framework, this value is forced to 10