Basic server with keepalive.

src/client/cspt-client.c

@@ -0,0 +1,94 @@
+// Client-Side Prediction Test - Client
+// Barra Ó Catháin - 2023
+#include <netdb.h>
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <strings.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include "../cspt-message.h"
+
+int main(int argc, char ** argv)
+{
+	uint8_t currentPlayerNumber = 0;
+	int serverSocket = 0;
+	bool continueRunning = true;
+	CsptMessage currentMessage;
+	struct sockaddr_in serverAddress;
+	
+	printf("Client-Side Prediction Test - Client Starting.\n");
+
+	// Give me a socket, and make sure it's working:
+	serverSocket = socket(AF_INET, SOCK_STREAM, 0);
+	if (serverSocket == -1)
+	{
+		printf("Socket creation failed.\n");
+		exit(EXIT_FAILURE);
+	}
+  
+	// Set our IP address and port. Default to localhost for testing:
+	serverAddress.sin_family = AF_INET;
+	serverAddress.sin_addr.s_addr = inet_addr("127.0.0.1");
+	serverAddress.sin_port = htons(5200);
+  
+	// Connect to the server:
+	if (connect(serverSocket, (struct sockaddr *)&serverAddress, sizeof(struct sockaddr_in)) != 0)
+	{
+		fprintf(stderr, "Connecting to the server failed.\n");
+		exit(0);
+	}
+
+	currentMessage.type = 0;
+	currentMessage.content = 0;
+
+	send(serverSocket, &currentMessage, sizeof(CsptMessage), 0);
+	recv(serverSocket, &currentMessage, sizeof(CsptMessage), 0);
+
+	if (currentMessage.type == 0)
+	{
+		currentPlayerNumber = currentMessage.content;
+	}
+
+	printf("Registered as: %u\n", currentPlayerNumber);
+	printf("%-7s | %u\n", messageStrings[currentMessage.type], currentMessage.content);
+	
+	while (continueRunning)
+	{
+		if (recv(serverSocket, &currentMessage, sizeof(CsptMessage), 0) > 0)
+		{
+			printf("%-7s | %u\n", messageStrings[currentMessage.type], currentMessage.content);
+			switch (currentMessage.type)
+			{
+				case 1:
+				{
+					// We've been told to disconnect:
+					shutdown(serverSocket, SHUT_RDWR);
+					serverSocket = 0;
+					continueRunning = false;
+					break;
+				}
+				case 2:
+				{
+					// Pinged, so we now must pong.
+					currentMessage.type = 3;
+					currentMessage.content = 0;
+					send(serverSocket, &currentMessage, sizeof(CsptMessage), 0);
+					break;
+				}
+			}
+		}
+		else
+		{
+			shutdown(serverSocket, SHUT_RDWR);
+			serverSocket = 0;
+			continueRunning = false;
+		}
+	}
+			
+	return 0;
+}

src/cspt-message.h

@@ -0,0 +1,17 @@
+#ifndef CSPT_MESSAGE_H
+#define CSPT_MESSAGE_H
+#include <stdint.h>
+const char * messageStrings[] = {"HELLO", "GOODBYE", "PING", "PONG"};
+typedef struct CsptMessage
+{
+	uint8_t type;
+	uint8_t content;
+} CsptMessage;
+
+/* Message Types:   
+   0 - HELLO: Contents sent to client indicate a given player number.
+   1 - GOODBYE: No contents, end the connection.
+   2 - PING: Contents indicate the missed amount of pongs.
+   3 - PONG: No contents.
+*/
+#endif

src/server/cspt-server.c

@@ -0,0 +1,237 @@
+// Client-Side Prediction Test - Server
+// Barra Ó Catháin - 2023
+#include <time.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <strings.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include "../cspt-message.h"
+bool keepRunning = true;
+
+struct connectionStatus
+{
+	uint8_t remainingPongs;	
+};
+
+void sigintHandler(int signal)
+{
+	keepRunning = false;
+}
+
+int main(int argc, char ** argv)
+{
+	int returnValue = 0;
+	int masterSocket = 0;
+	int clientSockets[16];
+	fd_set connectedClients;
+	struct connectionStatus clientStatus[16];
+	struct sockaddr_in serverAddress, clientAddress;
+	CsptMessage currentMessage;
+	printf("Client-Side Prediction Test - Server Starting.\n");
+
+	// Setup the sigint handler:
+	signal(SIGINT, sigintHandler);
+
+	// Setup TCP Master Socket:
+	printf("Setting up master socket... ");
+	masterSocket = socket(AF_INET, SOCK_STREAM, 0);
+	setsockopt(masterSocket, SOL_SOCKET, SO_REUSEPORT,  &(int){1}, sizeof(int));
+	if (masterSocket == -1)
+	{
+		fprintf(stderr, "Failed to get a socket.\n");
+		exit(1);
+	}
+
+	struct timeval timeout;
+	timeout.tv_sec = 1;
+	timeout.tv_usec = 0;
+	
+	// Set up server address struct:
+	bzero(&serverAddress, sizeof(serverAddress));
+	serverAddress.sin_family = AF_INET;
+	serverAddress.sin_addr.s_addr = htonl(INADDR_ANY);
+	serverAddress.sin_port = htons(5200);
+
+	// Bind the socket using the server address struct:
+	if (bind(masterSocket, (struct sockaddr *)&serverAddress, sizeof(struct sockaddr_in)) != 0)
+	{
+		fprintf(stderr, "Failed to bind the socket.\n");
+		exit(1);
+	}
+
+	// Begin listening:
+	if ((listen(masterSocket, 16) != 0))
+	{
+		fprintf(stderr, "Failed to begin listening.\n");
+		exit(1);
+	}
+
+	printf("Done!\n");
+
+	for (int index = 0; index < 16; index++)
+	{
+		clientSockets[index] = 0;
+	}
+
+	int clientCount = 0;
+	int activityCheck = 0;
+
+	// Prep the file descriptor set:
+	FD_ZERO(&connectedClients);
+	FD_SET(masterSocket, &connectedClients);
+
+	clientCount = masterSocket;
+
+	time_t lastPingTime;
+	time(&lastPingTime);
+	
+	while (keepRunning)
+	{
+		FD_ZERO(&connectedClients);
+		FD_SET(masterSocket, &connectedClients);
+		// Find all sockets that are still working and place them in the set:
+		for(int index = 0; index < 16; index++)
+		{
+			// If it's working, bang it into the list:
+			if(clientSockets[index] > 0)
+			{
+				FD_SET(clientSockets[index], &connectedClients);  
+			}
+			// The amount of clients is needed for select():
+			if(clientSockets[index] > clientCount)
+			{
+				clientCount = clientSockets[index];
+			}
+		}
+		
+		// Check what sockets have items ready to be read:
+		timeout.tv_sec = 1;
+		activityCheck = select(clientCount + 1, &connectedClients, NULL, NULL, &timeout);
+
+		// Check if select() worked:
+		if ((activityCheck < 0) && (errno != EINTR))  
+		{ 
+			fprintf(stderr, "Error in select(), retrying.\n");  
+		}
+		if (keepRunning)
+		{
+			// Check if there are any new connections:
+			if (FD_ISSET(masterSocket, &connectedClients))
+			{
+				// See if we have a slot for the fellow:
+				for (int index = 0; index < 16; index++)
+				{
+					if (clientSockets[index] == 0)
+					{
+						clientSockets[index] = accept(masterSocket, NULL, NULL);
+						FD_SET(clientSockets[index], &connectedClients);
+						if(clientSockets[index] > 0)
+						{
+							printf("Accepted new connection on socket %d.\n", index);
+							clientStatus[index].remainingPongs = 0;
+						}
+						if (clientSockets[index] > masterSocket)
+						{
+							clientCount = clientSockets[index];
+						}
+						break;
+					}
+				}
+			}
+			
+			for (int index = 0; index < 16; index++)
+			{
+				if (FD_ISSET(clientSockets[index], &connectedClients))
+				{
+					// The client has sent a message, recieve it and process:
+					if ((returnValue = recv(clientSockets[index], &currentMessage, sizeof(CsptMessage), 0)) > 0)
+					{
+						printf("%s, %u\n", messageStrings[currentMessage.type], currentMessage.content);					
+						switch (currentMessage.type)
+						{
+							// Hello:
+							case 0:
+							{
+								currentMessage.type = 0;
+								currentMessage.content = (uint8_t)random() % 16;
+								send(clientSockets[index], &currentMessage, sizeof(CsptMessage), 0);
+								break;
+							}
+							// Goodbye:
+							case 1:
+							{
+								FD_CLR(clientSockets[index], &connectedClients);
+								shutdown(clientSockets[index], SHUT_RDWR);
+								clientSockets[index] = 0;
+								break;
+							}
+							// Ping:
+							case 2:
+							{
+								// Dunno what the client is pingin' me for, so I don't care.
+								break;
+							}
+							// Pong:
+							case 3:
+							{
+								// One less pong to wait on:
+								clientStatus[index].remainingPongs--;
+								break;
+							}
+						}
+					}				
+					else if (returnValue == 0)
+					{
+						currentMessage.type = 1;
+						currentMessage.content = 0;
+						FD_CLR(clientSockets[index], &connectedClients);
+						send(clientSockets[index], &currentMessage, sizeof(CsptMessage), 0);
+						shutdown(clientSockets[index], SHUT_RDWR);
+						clientSockets[index] = 0;
+					}
+				}
+			}
+			if (time(NULL) >= (lastPingTime + 5))
+			{
+				time(&lastPingTime);
+				for (int index = 0; index < 16; index++)
+				{
+					if (clientSockets[index] > 0)
+					{
+						currentMessage.type = 2;
+						currentMessage.content = 0;
+						send(clientSockets[index], &currentMessage, sizeof(CsptMessage), 0);
+						clientStatus[index].remainingPongs++;
+						if (clientStatus[index].remainingPongs >= 10)
+						{
+							currentMessage.type = 1;
+							currentMessage.content = 0;
+							send(clientSockets[index], &currentMessage, sizeof(CsptMessage), 0);
+							shutdown(clientSockets[index], SHUT_RDWR);
+							clientSockets[index] = 0;
+						}
+					}
+				}
+				printf("Waiting on pongs.\n");
+			}
+		}
+	}
+	for (int index = 0; index < 16; index++)
+	{
+		currentMessage.type = 1;
+		currentMessage.content = 0;
+		send(clientSockets[index], &currentMessage, sizeof(CsptMessage), 0);
+		shutdown(clientSockets[index], SHUT_RDWR);
+		clientSockets[index] = 0;
+	}
+	shutdown(masterSocket, SHUT_RDWR);	
+	return 0;
+}