EthernetExamples/EthernetTcpServerHelloWorld_manual/EthernetTcpServerHelloWorld_manual.cpp

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/*
 * Title: EthernetTCPServer_manualClientManagement 
 *
 * Objective:
 *    This example demonstrates how to configure a ClearCore as a TCP server to 
 *    send and receive TCP datagrams (packets).
 *    
 * Description:
 *    This example configures a ClearCore device to act as a TCP server. 
 *    This server can receive connections from several other devices acting as TCP 
 *    clients to exchange data over ethernet TCP. 
 *    This simple example accepts connection requests from clients, checks for
 *    incoming data from connected devices, and sends a simple "Hello 
 *    client" response.
 *    A partner project, EthernetTcpClientHelloWorld, can be used to configure 
 *    another ClearCore as a client device.
 *
 * Setup:
 * 1. Set the usingDhcp boolean as appropriate. If not using DHCP, specify static 
 *    IP and network information.
 * 2. Ensure the server and client are setup to communicate on the same network.
 *    If server and client devices are directly connected (as opposed to through a switch)
 *    an ethernet crossover cable may be required. 
 * 3. It may be helpful to use another application to view serial output from 
 *    each device. PuTTY is one such application: https://www.putty.org/
 *
 * Links:
 * ** ClearCore Documentation: https://teknic-inc.github.io/ClearCore-library/
 * ** ClearCore Manual: https://www.teknic.com/files/downloads/clearcore_user_manual.pdf
 * 
 * Copyright (c) 2022 Teknic Inc. This work is free to use, copy and distribute under the terms of
 * the standard MIT permissive software license which can be found at https://opensource.org/licenses/MIT
 */

#include "ClearCore.h"
#include "EthernetTcpServer.h"

// The port number on the server over which packets will be sent/received 
#define PORT_NUM 8888

// The maximum number of characters to receive from an incoming packet
#define MAX_PACKET_LENGTH 100
// Buffer for holding received packets
unsigned char packetReceived[MAX_PACKET_LENGTH];
// Buffer for holding packets to send
char packetToSend[MAX_PACKET_LENGTH]; 

// Set total number of clients the server will accept
#define NUMBER_OF_CLIENTS 6

// Set usingDhcp to false to use user defined network settings
bool usingDhcp = true;

// Array of output LEDs to indicate client connections
// NOTE: only connectors IO0 through IO5 can be configured as digital outputs (LEDs) 
Connector *const outputLEDs[6] = {
    &ConnectorIO0, &ConnectorIO1, &ConnectorIO2, &ConnectorIO3, &ConnectorIO4, &ConnectorIO5
};


int main(void) {
    // Set up serial communication between ClearCore and PC serial terminal 
    ConnectorUsb.Mode(Connector::USB_CDC);
    ConnectorUsb.Speed(9600);
    ConnectorUsb.PortOpen();
    uint32_t timeout = 5000;
    uint32_t startTime = Milliseconds();
    while (!ConnectorUsb && Milliseconds() - startTime < timeout) {
        continue;
    }

    // Set connectors IO0-IO5 as a digital outputs 
    // When an outputLED's state is true, a LED will light on the
    // ClearCore indicating a successful connection to a client
    for(int i=0; i<6; i++){
    outputLEDs[i]->Mode(Connector::OUTPUT_DIGITAL);
    }
    
    // Make sure the physical link is active before continuing
    while (!EthernetMgr.PhyLinkActive()) {
        ConnectorUsb.SendLine("The Ethernet cable is unplugged...");
        Delay_ms(1000);
    }
    
    //To configure with an IP address assigned via DHCP
    EthernetMgr.Setup();
    if (usingDhcp) {
        // Use DHCP to configure the local IP address
        bool dhcpSuccess = EthernetMgr.DhcpBegin();
        if (dhcpSuccess) {
            ConnectorUsb.Send("DHCP successfully assigned an IP address: ");
            ConnectorUsb.SendLine(EthernetMgr.LocalIp().StringValue());
        }
        else {
            ConnectorUsb.SendLine("DHCP configuration was unsuccessful!");
            while (true) {
                // TCP will not work without a configured IP address
                continue;
            }
        }
    } else {
        // Configure with a manually assigned IP address
        
        // Set ClearCore's IP address
        IpAddress ip = IpAddress(192, 168, 0, 100);
        EthernetMgr.LocalIp(ip);
        ConnectorUsb.Send("Assigned manual IP address: ");
        ConnectorUsb.SendLine(EthernetMgr.LocalIp().StringValue());
        
        // Optionally, set additional network addresses if needed
        
        //IpAddress gateway = IpAddress(192, 168, 1, 1);
        //IpAddress netmask = IpAddress(255, 255, 255, 0);
        //EthernetMgr.GatewayIp(gateway);
        //EthernetMgr.NetmaskIp(netmask);
    }
    

    // Initialize the ClearCore as a server 
    // Clients connect on specified port (8888 by default)
    EthernetTcpServer server = EthernetTcpServer(PORT_NUM);
    
    // Initialize an array of clients
    // This array holds the information of any client that
    // is currently connected to the server, and is used by the
    // server to interact with these clients
    EthernetTcpClient clients[NUMBER_OF_CLIENTS];
    // Initialize an temporary client for client management
    EthernetTcpClient tempClient;
    
    bool newClient = 0;

    // Start listening for TCP connections
    server.Begin();

    ConnectorUsb.SendLine("Server now listening for client connections...");

    // Resets a timer used to display a list of connected clients
    startTime = 0;
    
    // Connect to clients, and send/receive packets
    while(true){
        
        // Obtain a reference to a connected client
        // This function returns a specific client once per connection attempt
        // To maintain a connection with a client using Accept() 
        // some basic client management must be performed
        tempClient = server.Accept();
        
        // Checks if server.Accept() has returned a new client
        if(tempClient.Connected()){
            newClient = 1; 
            
            for(int i=0; i<NUMBER_OF_CLIENTS; i++){
                //Checks for an available location to store a new client
                if(!clients[i].Connected()){
                    clients[i].Close();
                    clients[i] = tempClient;
                    ConnectorUsb.Send(clients[i].RemoteIp().StringValue());
                    ConnectorUsb.SendLine(" has been connected");
                    newClient = 0;
                    break;
                }
            }
            // Rejects client if the client list is full 
            if(newClient == 1){
                newClient = 0;
                tempClient.Send("This server has reached its max number of clients. Closing connection.");
                sprintf(packetToSend, "This server has reached its max number of clients. Closing connection to (%s).", tempClient.RemoteIp().StringValue());
                ConnectorUsb.SendLine(packetToSend);
                tempClient.Close();
            }
        }
        
        // Loops through list of clients to receive/send messages
        for(int i=0; i<NUMBER_OF_CLIENTS; i++){
            if (clients[i].Connected()) {
                
                // Indicate connection on corresponding output LED
                outputLEDs[i]->State(true);
                
                // Check if client has incoming data available  
                if(clients[i].BytesAvailable()){
                    sprintf(packetToSend, "Read the following from the client(%s): ", clients[i].RemoteIp().StringValue());
                    ConnectorUsb.Send(packetToSend);
                    // Read packet from the client
                    while (clients[i].BytesAvailable()) {
                        // Send the data received from the client over a serial port
                        clients[i].Read(packetReceived, MAX_PACKET_LENGTH);
                        ConnectorUsb.Send((char *)packetReceived);

                        // Clear the message buffer for the next iteration of the loop
                        for(int i=0; i<MAX_PACKET_LENGTH; i++){
                            packetReceived[i]=NULL;
                        }
                    }
                    ConnectorUsb.SendLine();
                    
                    //Sends unique response to the client
                    sprintf(packetToSend, "Hello client %s",clients[i].RemoteIp().StringValue());
                    if(clients[i].Send(packetToSend) == 0){
                        // If the message was unable to send, close the client connection
                        clients[i].Close();
                        sprintf(packetToSend, "Client (%s) has been removed from client list. ", clients[i].RemoteIp().StringValue());
                        ConnectorUsb.Send(packetToSend);
                        clients[i] = EthernetTcpClient();
                        
                        // Indicate loss of connection by turning off corresponding LED
                        outputLEDs[i]->State(false);
                    }

                }
                
            } else{
                // Removes any disconnected clients
                if(clients[i].RemoteIp() != IpAddress(0,0,0,0)){
                    sprintf(packetToSend, "Client (%s) has been removed from client list. ", clients[i].RemoteIp().StringValue());
                    ConnectorUsb.Send(packetToSend);
                    clients[i].Close();
                    clients[i] = EthernetTcpClient();

                    // Indicate loss of connection by turning off corresponding LED
                    outputLEDs[i]->State(false);
                }
            }
        }
        
        // Make sure the physical link is active before continuing
        while (!EthernetMgr.PhyLinkActive()) {
            ConnectorUsb.SendLine("The Ethernet cable is unplugged...");
            Delay_ms(1000);
        }
        
        // Print out a list of current clients
        int delay = 5000;
        if(Milliseconds()- startTime > delay){
            ConnectorUsb.SendLine("List of current clients: ");
            for(int i=0; i<NUMBER_OF_CLIENTS; i++){
                if(clients[i].RemoteIp() != IpAddress(0,0,0,0)){
                    sprintf(packetToSend, "Client %i = %s", i, clients[i].RemoteIp().StringValue());
                    ConnectorUsb.SendLine(packetToSend);
                }
            }
            startTime = Milliseconds();
        }
        
        // Perform any necessary periodic ethernet updates
        // Must be called regularly when actively using ethernet
        EthernetMgr.Refresh();
    }
}