connected client needs to provide a username which will be communicated to rejected clients

client.c

@@ -82,3 +82,46 @@ int client_write(struct client_t *client, char *databuf, int datalen) {
 	
 	return len;
 }
+
+/* Waits for client to provide a username. Blocks until a username is entered. */
+int client_ask_username(struct client_t *client) {
+	
+	int i;
+	char databuf[DATABUF_LEN];
+	fd_set read_fds;
+	
+	/* send username request to client */
+	snprintf(databuf, DATABUF_LEN,
+			 "\nPlease provide a username to identify yourself to other users (max %d characters):\n", USERNAME_LEN);
+	client_write(client, databuf, strlen(databuf));
+	
+	/* wait for client input */
+	client->username[0] = '\0';
+	while (client->username[0] == '\0') {
+		/* send prompt character to client */
+		snprintf(databuf, DATABUF_LEN, "> ");
+		client_write(client, databuf, strlen(databuf));
+		/* setup select() parameters */
+		FD_ZERO(&read_fds);
+		FD_SET(client->socket, &read_fds);
+		select((client->socket)+1, &read_fds, NULL, NULL, NULL);
+		if (FD_ISSET(client->socket, &read_fds)) {
+			client_read(client);
+			/* handle client input */
+			for (i = 0; i < USERNAME_LEN; i++) {
+				if (client->data[i] == '\r') {
+					break;
+				}
+				client->username[i] = client->data[i];
+			}
+			client->username[i+1] = '\0';
+		}
+	}
+	
+	/* send welcome message to client */
+	snprintf(databuf, DATABUF_LEN,
+			 "\nWelcome %s!\n\n", client->username);
+	client_write(client, databuf, strlen(databuf));
+	
+	return 0;
+}

feature_wishlist.txt

@@ -1,12 +0,0 @@
-- support multiple client connections at the same time
-	- first client has control
-	- additional clients can see the traffic
-		- read-only: requests from controlling client and responses from tty device
-	- need to avoid unintentional lock up if controlling client stays connected but user goes away and forgets about it
-		- additional clients should be able to force disconnecting controlling client
-		- first additional client that forces this becomes controlling client
-
-- require username when connecting to the server
-	- allows tracking users
-	- makes the feature above (forcing disconnect) easier to use
-		- username can be connected to a person easier than an IP address

moxerver.c

@@ -210,12 +210,14 @@ int main(int argc, char *argv[]) {
 						fprintf(stderr, "[%s] problem accepting client\n", NAME);
 						continue;
 					}
+					/* ask client to provide a username before going to "character" mode */
+					client_ask_username(&client);
 					/* put client in "character" mode */
 					telnet_set_character_mode(&client);
 				}
 				/* reject connection request if a client is already connected */
 				else {
-					server_reject(&server);
+					server_reject(&server, &client);
 				}
 			}
 			/* check client status if connected */

moxerver.h

@@ -17,6 +17,7 @@
 #define TIMESTAMP_FORMAT "%d.%m.%Y. %H:%M:%S"
 #define TIMESTAMP_LEN 20+1 /* calculated following timestamp format */
 #define CONFILE "moxanix.cfg"
+#define USERNAME_LEN 32
 
 /* Structures used for communication parameters. */
 struct server_t {
@@ -30,6 +31,7 @@ struct client_t {
 	struct sockaddr_in address; 		/* client address information */
 	char ip_string[INET_ADDRSTRLEN]; 	/* client IP address as a string */
 	time_t last_active; 				/* time of client's last activity in seconds from Epoch */
+	char username[USERNAME_LEN]; 		/* username for human identification */
 	char data[DATABUF_LEN]; 			/* buffer for data received from client */
 };
 
@@ -94,7 +96,7 @@ int server_accept(struct server_t *server, struct client_t *accepted_client);
  * Returns:
  * 0 always, errors with rejected client are ignored
  */
-int server_reject(struct server_t *server);
+int server_reject(struct server_t *server, struct client_t *client);
 
 
 /* Functions handling communication with clients. */
@@ -127,6 +129,15 @@ int client_read(struct client_t *client);
  */
 int client_write(struct client_t *client, char *databuf, int datalen);
 
+/**
+ * Waits for client to provide a username.
+ * Blocks until a username is entered.
+ *
+ * Returns:
+ * 0 always
+ */
+int client_ask_username(struct client_t *client);
+
 
 /* Functions handling details related to telnet protocol. */
 

server.c

@@ -104,7 +104,7 @@ int server_accept(struct server_t *server, struct client_t *accepted_client) {
 }
 
 /* Rejects incoming client connection. Errors with rejected client are ignored. */
-int server_reject(struct server_t *server) {
+int server_reject(struct server_t *server, struct client_t *client) {
 	
 	int namelen;
 	struct client_t rclient;
@@ -114,8 +114,10 @@ int server_reject(struct server_t *server) {
 	/* accept connection request */
 	namelen = sizeof(rclient.address);
 	rclient.socket = accept(server->socket, (struct sockaddr *) &rclient.address, (socklen_t *) &namelen);
-	/* send reject message */
-	sprintf(reject_msg, "[%s] port %u is already being used\n", __func__, server->port);
+	/* send reject message to client */
+	time2string(client->last_active, timestamp);
+	sprintf(reject_msg, "\nPort %u is already being used:\ncurrent user: %s\nlast activity: @ %s\n\n",
+			server->port, client->username, timestamp);
 	send(rclient.socket, reject_msg, strlen(reject_msg), 0);
 	/* close connection */
 	close(rclient.socket);