-extern int utcp_send(struct utcp_connection *connection, void *data, size_t len);
-extern int utcp_recv(struct utcp *utcp, void *data, size_t len);
-extern void utcp_close(struct utcp_connection *connection);
-extern void utcp_abort(struct utcp_connection *connection);
-extern void utcp_shutdown(struct utcp_connection *connection, int how);
-extern void utcp_timeout(struct utcp *utcp);
+extern ssize_t utcp_send(struct utcp_connection *connection, const void *data, size_t len);
+extern ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len);
+extern int utcp_close(struct utcp_connection *connection);
+extern int utcp_abort(struct utcp_connection *connection);
+extern int utcp_shutdown(struct utcp_connection *connection, int how);
+extern int utcp_timeout(struct utcp *utcp);
+
+// Global socket options
+
+extern int utcp_get_user_timeout(struct utcp *utcp);
+extern void utcp_set_user_timeout(struct utcp *utcp, int seconds);
+
+extern uint16_t utcp_get_mtu(struct utcp *utcp);
+extern void utcp_set_mtu(struct utcp *utcp, uint16_t mtu);
+
+// Per-socket options
+
+extern size_t utcp_get_sndbuf(struct utcp_connection *connection);
+extern void utcp_set_sndbuf(struct utcp_connection *connection, size_t size);
+
+extern bool utcp_get_nodelay(struct utcp_connection *connection);
+extern void utcp_set_nodelay(struct utcp_connection *connection, bool nodelay);
+
+extern bool utcp_get_keepalive(struct utcp_connection *connection);
+extern void utcp_set_keepalive(struct utcp_connection *connection, bool keepalive);
+
+extern size_t utcp_get_outq(struct utcp_connection *connection);