Basic protocol structure on the server side

src/common/ClientRequest.h

@@ -0,0 +1,50 @@
+/*
+
+  LibreFront --- an OpenFront clone
+  Copyright (C) 2025  Adrien Jaguenet
+  Copyright (C) 2025  Emil Kosz
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+*/
+
+#pragma once
+
+#include <common/PlayerConnection.h>
+
+typedef struct  {
+  char name[32];
+  //TODO: clan tag, flag, territory pattern under a PlayerInfo struct
+  int gameID;
+} JoinRequest;
+
+typedef struct {
+  int playerID;
+  union {
+    JoinRequest join;
+  } req;
+} ClientRequest;
+
+/* These prototypes are shared between client and server, but their implementation will be different
+ * and will be found in client/ClientRequest.c and server/ClientRequest.c */
+
+/*
+ * @param playerConn: player connection info
+ * @param req: the request to be sent (client) or received (server)
+ * @return: on success, the playerID, -1 on failure
+ */
+int requestJoinGame(PlayerConnection* playerConn, JoinRequest* req);
+
+
+

src/common/PlayerConnection.h

@@ -0,0 +1,39 @@
+/*
+
+  LibreFront --- an OpenFront clone
+  Copyright (C) 2025  Adrien Jaguenet
+  Copyright (C) 2025  Emil Kosz
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+*/
+
+#pragma once
+
+#include <gio/gio.h>
+
+typedef struct {
+  GSocket* socket;
+  GSocketConnection* connection;
+
+  /* Obviously, the client's istream is the server's ostream, and vice versa*/
+  GInputStream* istream;
+  GOutputStream* ostream;
+} PlayerConnection;
+
+PlayerConnection* PlayerConnection_accept(GSocket* socket);
+void PlayerConnection_close(PlayerConnection** self);
+
+void PlayerConnection_sendErrorResponse(PlayerConnection* self, const char fmt[], ...);
+

src/common/ServerResponse.h

@@ -0,0 +1,27 @@
+/*
+
+  LibreFront --- an OpenFront clone
+  Copyright (C) 2025  Adrien Jaguenet
+  Copyright (C) 2025  Emil Kosz
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+*/
+
+#pragma once
+
+typedef struct {
+  void* data;
+} ServerResponse;
+

src/common/messaging.c

@@ -0,0 +1,21 @@
+#include "messaging.h"
+
+int Message_read(GInputStream* stream, Message* message) {
+  GError *error;
+  gssize n =
+    g_input_stream_read (stream, &(message->header), sizeof(message->header), NULL,
+                          &error);
+  if (n < 0) {
+    g_error("Could not g_input_stream_read() %s", error->message);
+    g_clear_error(&error);
+    return -1;
+  } else {
+    g_info("Received message with version=%d, data_size=%d, type=%x", message->header.version, message->header.data_size, message->header.type);
+  }
+
+  if (message->header.version != PROTOCOL_VERSION) {
+    g_error("Wrong protocol (expects %d, received %d)", PROTOCOL_VERSION, message->header.version);
+    return -1;
+  }
+  return 0;
+}

src/common/messaging.h

@@ -0,0 +1,56 @@
+/*
+
+  LibreFront --- an OpenFront clone
+  Copyright (C) 2025  Adrien Jaguenet
+  Copyright (C) 2025  Emil Kosz
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+*/
+
+#pragma once
+
+#include <glib.h>
+
+#include "ClientRequest.h"
+#include "ServerResponse.h"
+
+#define PROTOCOL_VERSION 0x1
+
+typedef enum {
+  RESPONSE_ERROR = 0xffffffff,
+} ResponseType;
+
+typedef enum {
+  REQUEST_HELLO =    0x00000001,
+  REQUEST_JOINGAME = 0x00000002,
+} RequestType;
+
+typedef struct {
+  guint32 version;
+  guint32 type;
+  guint32 data_size;
+} MessageHeader;
+
+typedef struct {
+  MessageHeader header;
+  void* data;
+} Message;
+
+/* @param stream: input stream (from a socket ideally)
+ * @param message: message structure that will be read into
+ * @return -1 on error
+ * */
+int Message_read(GInputStream* stream, Message* message);
+

src/common/player.h

@@ -0,0 +1,27 @@
+/*
+
+  LibreFront --- an OpenFront clone
+  Copyright (C) 2025  Adrien Jaguenet
+  Copyright (C) 2025  Emil Kosz
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+*/
+
+#pragma once
+
+typedef struct {
+
+} PlayerInfo;
+

src/server/ClientRequest.c

@@ -0,0 +1,38 @@
+/*
+
+  LibreFront --- an OpenFront clone
+  Copyright (C) 2025  Adrien Jaguenet
+  Copyright (C) 2025  Emil Kosz
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+*/
+
+#include <common/ClientRequest.h>
+
+int requestJoinGame(PlayerConnection* playerConn, JoinRequest* req) {
+  if (1 /*TODO game ID is not correct */) {
+    PlayerConnection_sendErrorResponse(playerConn, "Incorrect game ID %d", req->gameID);
+  }
+  if (1 /*TODO: username is not valid */ ) {
+    //WARNING: zero-terminated string?
+    PlayerConnection_sendErrorResponse(playerConn, "Invalid username '%s'", req->name);
+  }
+  if (1 /*TODO: Check that the game is not full*/) {
+    PlayerConnection_sendErrorResponse(playerConn, "Game with ID %d is full", req->gameID);
+  }
+  int playerID = -1 /*TODO: Select a pseudo-random unique positive integer to serve as the player's "secret" ID*/;
+  return playerID;
+}
+

src/server/PlayerConnection.c

@@ -0,0 +1,97 @@
+/*
+
+  LibreFront --- an OpenFront clone
+  Copyright (C) 2025  Adrien Jaguenet
+  Copyright (C) 2025  Emil Kosz
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+*/
+
+#include <common/PlayerConnection.h>
+#include <common/messaging.h>
+
+PlayerConnection* PlayerConnection_accept(GSocket* socket) {
+  GError* error = NULL;
+  PlayerConnection *pconn = g_new0(PlayerConnection, 1);
+
+  pconn->socket = g_socket_accept (socket, NULL, &error);
+  pconn->connection =
+	g_socket_connection_factory_create_connection (pconn->socket);
+
+
+  if (!pconn->connection)
+  {
+    g_printerr ("accept() failed: %s\n", error->message);
+    goto error_flow;
+  }
+  else
+  {
+    g_info ("New connection accepted");
+  }
+
+  pconn->istream = g_io_stream_get_input_stream (G_IO_STREAM (pconn->connection));
+  if (!pconn->istream) {
+    g_printerr("Could not get input stream: %s", error->message);
+    goto error_flow;
+  }
+  else
+  {
+    g_info ("Got input stream.");
+  }
+
+  pconn->ostream = g_io_stream_get_output_stream (G_IO_STREAM (pconn->connection));
+  if (!pconn->ostream) {
+    g_printerr("Could not get output stream: %s", error->message);
+    goto error_flow;
+  }
+  else
+  {
+    g_info ("Got output stream.");
+  }
+
+  return pconn;
+
+error_flow:
+  g_clear_error (&error);
+  PlayerConnection_close(&pconn);
+  return NULL;
+}
+
+void PlayerConnection_close(PlayerConnection** self) {
+  g_io_stream_close (G_IO_STREAM (*self), NULL, NULL);
+  g_object_unref ((*self)->connection);
+  g_object_unref ((*self)->socket);
+  g_free(*self);
+  *self = NULL;
+}
+
+void PlayerConnection_sendErrorResponse(PlayerConnection* self, const char fmt[], ...) {
+  //WARNING: is this safe against non-null-terminated strings?
+  GError *error = NULL;
+
+  va_list args;
+  va_start(args);
+
+  gsize bytes_written = 0;
+  Message msg;
+  //TODO: create a proper ErrorResponse object
+  msg.header.version = PROTOCOL_VERSION;
+  msg.header.type = RESPONSE_ERROR;
+  msg.header.data_size = 0;
+  g_output_stream_write(self->ostream, &msg, sizeof(msg.header), NULL, &error);
+  g_output_stream_vprintf (self->ostream, &bytes_written, NULL, &error, fmt, args);
+  g_output_stream_flush (self->ostream, NULL, &error);
+  va_end(args);
+}

src/server/server.c

@@ -3,6 +3,8 @@
 #include <glib.h>
 #include <gio/gio.h>
 
+#include <common/PlayerConnection.h>
+
 int
 main (int argc, char *argv[])
 {
@@ -13,100 +15,80 @@ main (int argc, char *argv[])
   GError *error = NULL;
   int PORT = SERVER_DEFAULT_PORT;
   if (argc > 1)
-    {
+  {
-      PORT = atoi (argv[1]);
+    PORT = atoi (argv[1]);
-      g_info ("Changed the listening port from default=%d to custom=%d",
+    g_info ("Changed the listening port from default=%d to custom=%d",
-	      SERVER_DEFAULT_PORT, PORT);
+            SERVER_DEFAULT_PORT, PORT);
-    }
+  }
   GSocket *socket = g_socket_new (G_SOCKET_FAMILY_IPV4, G_SOCKET_TYPE_STREAM,
-				  G_SOCKET_PROTOCOL_TCP, &error);
+                                  G_SOCKET_PROTOCOL_TCP, &error);
   if (!socket)
-    {
+  {
-      g_printerr ("Socket creation failed: %s\n", error->message);
+    g_printerr ("Socket creation failed: %s\n", error->message);
-      g_clear_error (&error);
+    g_clear_error (&error);
-      return -1;
+    return -1;
-    }
+  }
   else
-    {
+{
-      g_info ("Created TCP socket.");
+    g_info ("Created TCP socket.");
-    }
+  }
 
   GInetAddress *addr = g_inet_address_new_any (G_SOCKET_FAMILY_IPV4);
   GSocketAddress *sockaddr = g_inet_socket_address_new (addr, PORT);
 
   if (!g_socket_bind (socket, sockaddr, TRUE, &error))
-    {
+  {
-      g_printerr ("Bind failed: %s\n", error->message);
+    g_printerr ("Bind failed: %s\n", error->message);
-      g_clear_error (&error);
+    g_clear_error (&error);
-      g_object_unref (socket);
+    g_object_unref (socket);
-    }
+  }
   else
-    {
+{
-      g_info ("Bound TCP socket to port %d", PORT);
+    g_info ("Bound TCP socket to port %d", PORT);
-    }
+  }
 
   g_object_unref (addr);
   g_object_unref (sockaddr);
 
   if (!g_socket_listen (socket, &error))
-    {
+  {
-      g_printerr ("Listen failed: %s\n", error->message);
+    g_printerr ("Listen failed: %s\n", error->message);
-      g_clear_error (&error);
+    g_clear_error (&error);
-      g_object_unref (socket);
+    g_object_unref (socket);
-      return -1;
+    return -1;
-    }
+  }
   else
-    {
+{
-      g_info ("TCP socket is now listening");
+    g_info ("TCP socket is now listening");
-    }
+  }
 
   g_info ("Listening...");
   while (true)
-    {
+  {
-      GSocket *socket2 = g_socket_accept (socket, NULL, &error);
+    PlayerConnection *playerConnection = PlayerConnection_accept(socket);
-      GSocketConnection *connection =
+    if (! playerConnection) {
-	g_socket_connection_factory_create_connection (socket2);
+      g_printerr("Error creating a player connection");
-      if (!connection)
-	{
-	  g_printerr ("accept() failed: %s\n", error->message);
-	  g_clear_error (&error);
-	  continue;
-	}
-      else
-	{
-	  g_info ("New connection accepted");
-	}
-
-      GInputStream *istream =
-	g_io_stream_get_input_stream (G_IO_STREAM (connection));
-      gchar buffer[1024];
-      gssize n =
-	g_input_stream_read (istream, buffer, sizeof (buffer) - 1, NULL,
-			     &error);
-
-      if (n > 0)
-	{
-	  buffer[n] = '\0';
-	  g_print ("Received from client: %s\n", buffer);
-	}
-      else
-	{
-	  g_printerr ("Read error: %s\n", error->message);
-	  g_clear_error (&error);
-	}
-
-      GOutputStream *ostream =
-	g_io_stream_get_output_stream (G_IO_STREAM (connection));
-      const gchar *response =
-	"Hello from the librefront server. Not implemented!!";
-      g_output_stream_write (ostream, response, strlen (response), NULL,
-			     &error);
-      g_output_stream_flush (ostream, NULL, &error);
-
-      g_io_stream_close (G_IO_STREAM (connection), NULL, NULL);
-      g_object_unref (connection);
-      g_object_unref (socket2);
     }
+    gchar buffer[1024];
+    gssize n =
+      g_input_stream_read (playerConnection->istream, buffer, sizeof (buffer) - 1, NULL,
+                           &error);
+
+    if (n > 0)
+    {
+      buffer[n] = '\0';
+      g_print ("Received from client: %s\n", buffer);
+    }
+    else
+    {
+      g_printerr ("Read error: %s\n", error->message);
+      g_clear_error (&error);
+    }
+
+    PlayerConnection_sendErrorResponse(playerConnection, "This is an error response");
+
+    PlayerConnection_close(&playerConnection);
+  }
 
   g_object_unref (socket);
   fprintf (stderr, "Server not implemented!\n");