Extract client functions into a separate header

client.h

@@ -0,0 +1,48 @@
+/* Handles communication with clients. */
+
+#include <moxerver.h>
+
+/**
+ * Closes a client connection.
+ */
+void client_close(client_t *client);
+
+/**
+ * Reads data from a client into the client data buffer.
+ * Also updates the timestamp of the client's last activity.
+ *
+ * Returns:
+ * - number of read bytes on success,
+ * - negative ENODATA value (-ENODATA) if the client has disconnected,
+ * - negative errno value set by an error while reading
+ */
+int client_read(client_t *client);
+
+/**
+ * Sends data from a buffer to the client.
+ *
+ * Returns:
+ * - number of sent bytes on success,
+ * - negative errno value set by an error while sending
+ */
+int client_write(client_t *client, char *databuf, int datalen);
+
+/**
+ * Waits for input from the client in "line mode" (client sends a whole line of
+ * characters). The function blocks until input arrives.
+ *
+ * Returns:
+ * - 0 on success
+ * - negative value if error occurred
+ */
+int client_wait_line(client_t *client);
+
+/**
+ * Asks the client to provide a username.
+ * Blocks until a string is provided.
+ *
+ * Returns:
+ * - 0 on success
+ * - negative value if error occurred
+ */
+int client_ask_username(client_t *client);