+static int relay_process_control_receive_payload(struct relay_connection *conn)
+{
+ int ret = 0;
+ struct lttng_dynamic_buffer *reception_buffer =
+ &conn->protocol.ctrl.reception_buffer;
+ struct ctrl_connection_state_receive_payload *state =
+ &conn->protocol.ctrl.state.receive_payload;
+ struct lttng_buffer_view payload_view;
+
+ if (state->left_to_receive == 0) {
+ /* Short-circuit for payload-less commands. */
+ goto reception_complete;
+ }
+
+ ret = conn->sock->ops->recvmsg(conn->sock,
+ reception_buffer->data + state->received,
+ state->left_to_receive, MSG_DONTWAIT);
+ if (ret < 0) {
+ ERR("Unable to receive command payload on sock %d", conn->sock->fd);
+ goto end;
+ } else if (ret == 0) {
+ DBG("Socket %d performed an orderly shutdown (received EOF)", conn->sock->fd);
+ ret = -1;
+ goto end;
+ }
+
+ assert(ret > 0);
+ assert(ret <= state->left_to_receive);
+
+ state->left_to_receive -= ret;
+ state->received += ret;
+
+ if (state->left_to_receive > 0) {
+ /*
+ * Can't transition to the protocol's next state, wait to
+ * receive the rest of the header.
+ */
+ DBG3("Partial reception of control connection protocol payload (received %" PRIu64 " bytes, %" PRIu64 " bytes left to receive, fd = %i)",
+ state->received, state->left_to_receive,
+ conn->sock->fd);
+ ret = 0;
+ goto end;
+ }
+
+reception_complete:
+ DBG("Done receiving control command payload: fd = %i, payload size = %" PRIu64 " bytes",
+ conn->sock->fd, state->received);
+ /*
+ * The payload required to process the command has been received.
+ * A view to the reception buffer is forwarded to the various
+ * commands and the state of the control is reset on success.
+ *
+ * Commands are responsible for sending their reply to the peer.
+ */
+ payload_view = lttng_buffer_view_from_dynamic_buffer(reception_buffer,
+ 0, -1);
+ ret = relay_process_control_command(conn,
+ &state->header, &payload_view);
+ if (ret < 0) {
+ goto end;
+ }
+
+ ret = connection_reset_protocol_state(conn);
+end:
+ return ret;
+}
+
+static int relay_process_control_receive_header(struct relay_connection *conn)
+{
+ int ret = 0;
+ struct lttcomm_relayd_hdr header;
+ struct lttng_dynamic_buffer *reception_buffer =
+ &conn->protocol.ctrl.reception_buffer;
+ struct ctrl_connection_state_receive_header *state =
+ &conn->protocol.ctrl.state.receive_header;
+
+ assert(state->left_to_receive != 0);
+
+ ret = conn->sock->ops->recvmsg(conn->sock,
+ reception_buffer->data + state->received,
+ state->left_to_receive, MSG_DONTWAIT);
+ if (ret < 0) {
+ ERR("Unable to receive control command header on sock %d", conn->sock->fd);
+ goto end;
+ } else if (ret == 0) {
+ DBG("Socket %d performed an orderly shutdown (received EOF)", conn->sock->fd);
+ ret = -1;
+ goto end;
+ }
+
+ assert(ret > 0);
+ assert(ret <= state->left_to_receive);
+
+ state->left_to_receive -= ret;
+ state->received += ret;
+
+ if (state->left_to_receive > 0) {
+ /*
+ * Can't transition to the protocol's next state, wait to
+ * receive the rest of the header.
+ */
+ DBG3("Partial reception of control connection protocol header (received %" PRIu64 " bytes, %" PRIu64 " bytes left to receive, fd = %i)",
+ state->received, state->left_to_receive,
+ conn->sock->fd);
+ ret = 0;
+ goto end;
+ }
+
+ /* Transition to next state: receiving the command's payload. */
+ conn->protocol.ctrl.state_id =
+ CTRL_CONNECTION_STATE_RECEIVE_PAYLOAD;
+ memcpy(&header, reception_buffer->data, sizeof(header));
+ header.circuit_id = be64toh(header.circuit_id);
+ header.data_size = be64toh(header.data_size);
+ header.cmd = be32toh(header.cmd);
+ header.cmd_version = be32toh(header.cmd_version);
+ memcpy(&conn->protocol.ctrl.state.receive_payload.header,
+ &header, sizeof(header));
+
+ DBG("Done receiving control command header: fd = %i, cmd = %" PRIu32 ", cmd_version = %" PRIu32 ", payload size = %" PRIu64 " bytes",
+ conn->sock->fd, header.cmd, header.cmd_version,
+ header.data_size);
+
+ /* FIXME temporary arbitrary limit on data size. */
+ if (header.data_size > (128 * 1024 * 1024)) {
+ ERR("Command header indicates a payload (%" PRIu64 " bytes) that exceeds the maximal payload size allowed on a control connection.",
+ header.data_size);
+ ret = -1;
+ goto end;
+ }
+
+ conn->protocol.ctrl.state.receive_payload.left_to_receive =
+ header.data_size;
+ conn->protocol.ctrl.state.receive_payload.received = 0;
+ ret = lttng_dynamic_buffer_set_size(reception_buffer,
+ header.data_size);
+ if (ret) {
+ goto end;
+ }
+
+ if (header.data_size == 0) {
+ /*
+ * Manually invoke the next state as the poll loop
+ * will not wake-up to allow us to proceed further.
+ */
+ ret = relay_process_control_receive_payload(conn);
+ }
+end:
+ return ret;
+}
+
+/*
+ * Process the commands received on the control socket
+ */
+static int relay_process_control(struct relay_connection *conn)
+{
+ int ret = 0;
+
+ switch (conn->protocol.ctrl.state_id) {
+ case CTRL_CONNECTION_STATE_RECEIVE_HEADER:
+ ret = relay_process_control_receive_header(conn);
+ break;
+ case CTRL_CONNECTION_STATE_RECEIVE_PAYLOAD:
+ ret = relay_process_control_receive_payload(conn);
+ break;
+ default:
+ ERR("Unknown control connection protocol state encountered.");
+ abort();
+ }
+
+ return ret;
+}
+