CUSTOM: relayd protocol: ignore reply on relayd_send_index and relayd_send_close_stream

[lttng-tools.git] / src / common / relayd / relayd.c

/*
 * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License, version 2 only, as
 * published by the Free Software Foundation.
 *
 * 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 General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define _LGPL_SOURCE
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <inttypes.h>

#include <common/common.h>
#include <common/defaults.h>
#include <common/compat/endian.h>
#include <common/sessiond-comm/relayd.h>
#include <common/index/ctf-index.h>

#include "relayd.h"

/*
 * Send command. Fill up the header and append the data.
 */
static int send_command(struct lttcomm_relayd_sock *rsock,
		enum lttcomm_relayd_command cmd, void *data, size_t size,
		int flags)
{
	int ret;
	struct lttcomm_relayd_hdr header;
	char *buf;
	uint64_t buf_size = sizeof(header);

	if (rsock->sock.fd < 0) {
		return -ECONNRESET;
	}

	if (data) {
		buf_size += size;
	}

	buf = zmalloc(buf_size);
	if (buf == NULL) {
		PERROR("zmalloc relayd send command buf");
		ret = -1;
		goto alloc_error;
	}

	memset(&header, 0, sizeof(header));
	header.cmd = htobe32(cmd);
	header.data_size = htobe64(size);

	/* Zeroed for now since not used. */
	header.cmd_version = 0;
	header.circuit_id = 0;

	/* Prepare buffer to send. */
	memcpy(buf, &header, sizeof(header));
	if (data) {
		memcpy(buf + sizeof(header), data, size);
	}

	DBG3("Relayd sending command %d of size %" PRIu64, (int) cmd, buf_size);
	ret = rsock->sock.ops->sendmsg(&rsock->sock, buf, buf_size, flags);
	if (ret < 0) {
		PERROR("Failed to send command %d of size %" PRIu64,
				(int) cmd, buf_size);
		ret = -errno;
		goto error;
	}
error:
	free(buf);
alloc_error:
	return ret;
}

static int recv_reply_ignore(struct lttcomm_relayd_sock *rsock, size_t size)
{
	int ret;
	size_t cutfoff = 128;

	/*
	 * To prevent ever growing size of recv_reply to ignore, if the number
	 * of bytes we want to ignore is bigger than `cutoff`, consume half of
	 * the cutoff. We might block on it but still, most of bytes to ignore
	 * should already be ready to consume at this point.
	 *
	 * This kind of scenario can easily happen on stopped session with a
	 * live_timer since no actual receive is done on the socket that would
	 * discard the `ignore` portion.
	 *
	 * TCP guarantee in-order transmission both on send and receive so this
	 * is safe to do.
	 */
	if (rsock->bytes_to_ignore_on_recv >= cutfoff) {
		size_t to_discard = cutfoff / 2;

		ret = rsock->sock.ops->recvmsg(&rsock->sock, NULL, to_discard, MSG_TRUNC);
		if (ret <= 0 || ret != to_discard) {
			if (ret == 0) {
				/* Orderly shutdown. */
				DBG("Socket %d has performed an orderly shutdown", rsock->sock.fd);
			} else {
				DBG("Receiving reply to discard failed on sock %d for size %zu with ret %d",
						rsock->sock.fd, to_discard, ret);
			}
			ret = -1;
			goto error;
		}

		DBG("Force discard of %zu bytes for socket %d", to_discard, rsock->sock.fd);
		rsock->bytes_to_ignore_on_recv -= to_discard;
	}

	DBG3("Relayd ignore reply of %zu bytes for socket %d.", size, rsock->sock.fd);
	/* Do not wait for the current reply to be ignored */
	rsock->bytes_to_ignore_on_recv += size;
	ret = 0;

error:
	return ret;
}

/*
 * Receive reply data on socket. This MUST be call after send_command or else
 * could result in unexpected behavior(s).
 */
static int recv_reply(struct lttcomm_relayd_sock *rsock, void *data, size_t size)
{
	int ret;

	if (rsock->sock.fd < 0) {
		return -ECONNRESET;
	}

	/*
	 * We have to consume the bytes that are marked to ignore.
	 */
	if (rsock->bytes_to_ignore_on_recv != 0) {
		ret = rsock->sock.ops->recvmsg(&rsock->sock, NULL, rsock->bytes_to_ignore_on_recv, MSG_TRUNC);
		if (ret <= 0 || ret != rsock->bytes_to_ignore_on_recv) {
			if (ret == 0) {
				/* Orderly shutdown. */
				DBG("Socket %d has performed an orderly shutdown", rsock->sock.fd);
			} else {
				DBG("Receiving reply to skip failed on sock %d for size %zu with ret %d",
						rsock->sock.fd, rsock->bytes_to_ignore_on_recv, ret);
			}
			ret = -1;
			goto error;
		}
		DBG("Discarded %zu bytes on sock %d", rsock->bytes_to_ignore_on_recv, rsock->sock.fd);
		rsock->bytes_to_ignore_on_recv = 0;
	}

	DBG3("Relayd waiting for reply of size %zu", size);

	ret = rsock->sock.ops->recvmsg(&rsock->sock, data, size, 0);
	if (ret <= 0 || ret != size) {
		if (ret == 0) {
			/* Orderly shutdown. */
			DBG("Socket %d has performed an orderly shutdown", rsock->sock.fd);
		} else {
			DBG("Receiving reply failed on sock %d for size %zu with ret %d",
					rsock->sock.fd, size, ret);
		}
		/* Always return -1 here and the caller can use errno. */
		ret = -1;
		goto error;
	}

error:
	return ret;
}

/*
 * Starting at 2.4, RELAYD_CREATE_SESSION takes additional parameters to
 * support the live reading capability.
 */
static int relayd_create_session_2_4(struct lttcomm_relayd_sock *rsock,
		uint64_t *session_id, char *session_name, char *hostname,
		int session_live_timer, unsigned int snapshot)
{
	int ret;
	struct lttcomm_relayd_create_session_2_4 msg;

	if (lttng_strncpy(msg.session_name, session_name,
			sizeof(msg.session_name))) {
		ret = -1;
		goto error;
	}
	if (lttng_strncpy(msg.hostname, hostname, sizeof(msg.hostname))) {
		ret = -1;
		goto error;
	}
	msg.live_timer = htobe32(session_live_timer);
	msg.snapshot = htobe32(snapshot);

	/* Send command */
	ret = send_command(rsock, RELAYD_CREATE_SESSION, &msg, sizeof(msg), 0);
	if (ret < 0) {
		goto error;
	}

error:
	return ret;
}

/*
 * RELAYD_CREATE_SESSION from 2.1 to 2.3.
 */
static int relayd_create_session_2_1(struct lttcomm_relayd_sock *rsock,
		uint64_t *session_id)
{
	int ret;

	/* Send command */
	ret = send_command(rsock, RELAYD_CREATE_SESSION, NULL, 0, 0);
	if (ret < 0) {
		goto error;
	}

error:
	return ret;
}

/*
 * Send a RELAYD_CREATE_SESSION command to the relayd with the given socket and
 * set session_id of the relayd if we have a successful reply from the relayd.
 *
 * On success, return 0 else a negative value which is either an errno error or
 * a lttng error code from the relayd.
 */
int relayd_create_session(struct lttcomm_relayd_sock *rsock, uint64_t *session_id,
		char *session_name, char *hostname, int session_live_timer,
		unsigned int snapshot)
{
	int ret;
	struct lttcomm_relayd_status_session reply;

	assert(rsock);
	assert(session_id);

	DBG("Relayd create session");

	switch(rsock->minor) {
		case 1:
		case 2:
		case 3:
			ret = relayd_create_session_2_1(rsock, session_id);
			break;
		case 4:
		default:
			ret = relayd_create_session_2_4(rsock, session_id, session_name,
					hostname, session_live_timer, snapshot);
			break;
	}

	if (ret < 0) {
		goto error;
	}

	/* Receive response */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	reply.session_id = be64toh(reply.session_id);
	reply.ret_code = be32toh(reply.ret_code);

	/* Return session id or negative ret code. */
	if (reply.ret_code != LTTNG_OK) {
		ret = -1;
		ERR("Relayd create session replied error %d", reply.ret_code);
		goto error;
	} else {
		ret = 0;
		*session_id = reply.session_id;
	}

	DBG("Relayd session created with id %" PRIu64, reply.session_id);

error:
	return ret;
}

/*
 * Add stream on the relayd and assign stream handle to the stream_id argument.
 *
 * On success return 0 else return ret_code negative value.
 */
int relayd_add_stream(struct lttcomm_relayd_sock *rsock, const char *channel_name,
		const char *pathname, uint64_t *stream_id,
		uint64_t tracefile_size, uint64_t tracefile_count)
{
	int ret;
	struct lttcomm_relayd_add_stream msg;
	struct lttcomm_relayd_add_stream_2_2 msg_2_2;
	struct lttcomm_relayd_status_stream reply;

	/* Code flow error. Safety net. */
	assert(rsock);
	assert(channel_name);
	assert(pathname);

	DBG("Relayd adding stream for channel name %s", channel_name);

	/* Compat with relayd 2.1 */
	if (rsock->minor == 1) {
		memset(&msg, 0, sizeof(msg));
		if (lttng_strncpy(msg.channel_name, channel_name,
				sizeof(msg.channel_name))) {
			ret = -1;
			goto error;
		}
		if (lttng_strncpy(msg.pathname, pathname,
				sizeof(msg.pathname))) {
			ret = -1;
			goto error;
		}

		/* Send command */
		ret = send_command(rsock, RELAYD_ADD_STREAM, (void *) &msg, sizeof(msg), 0);
		if (ret < 0) {
			goto error;
		}
	} else {
		memset(&msg_2_2, 0, sizeof(msg_2_2));
		/* Compat with relayd 2.2+ */
		if (lttng_strncpy(msg_2_2.channel_name, channel_name,
				sizeof(msg_2_2.channel_name))) {
			ret = -1;
			goto error;
		}
		if (lttng_strncpy(msg_2_2.pathname, pathname,
				sizeof(msg_2_2.pathname))) {
			ret = -1;
			goto error;
		}
		msg_2_2.tracefile_size = htobe64(tracefile_size);
		msg_2_2.tracefile_count = htobe64(tracefile_count);

		/* Send command */
		ret = send_command(rsock, RELAYD_ADD_STREAM, (void *) &msg_2_2, sizeof(msg_2_2), 0);
		if (ret < 0) {
			goto error;
		}
	}

	/* Waiting for reply */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	/* Back to host bytes order. */
	reply.handle = be64toh(reply.handle);
	reply.ret_code = be32toh(reply.ret_code);

	/* Return session id or negative ret code. */
	if (reply.ret_code != LTTNG_OK) {
		ret = -1;
		ERR("Relayd add stream replied error %d", reply.ret_code);
	} else {
		/* Success */
		ret = 0;
		*stream_id = reply.handle;
	}

	DBG("Relayd stream added successfully with handle %" PRIu64,
		reply.handle);

error:
	return ret;
}

/*
 * Add stream on the relayd. Send part.
 *
 * On success return 0 else return ret_code negative value.
 */
int relayd_add_stream_send(struct lttcomm_relayd_sock *rsock, const char *channel_name,
		const char *pathname, uint64_t tracefile_size, uint64_t tracefile_count)
{
	int ret;
	struct lttcomm_relayd_add_stream msg;
	struct lttcomm_relayd_add_stream_2_2 msg_2_2;

	/* Code flow error. Safety net. */
	assert(rsock);
	assert(channel_name);
	assert(pathname);

	DBG("Relayd adding stream for channel name %s. Part send", channel_name);

	/* Compat with relayd 2.1 */
	if (rsock->minor == 1) {
		memset(&msg, 0, sizeof(msg));
		if (lttng_strncpy(msg.channel_name, channel_name,
				sizeof(msg.channel_name))) {
			ret = -1;
			goto error;
		}
		if (lttng_strncpy(msg.pathname, pathname,
				sizeof(msg.pathname))) {
			ret = -1;
			goto error;
		}

		/* Send command */
		ret = send_command(rsock, RELAYD_ADD_STREAM, (void *) &msg, sizeof(msg), 0);
		if (ret < 0) {
			goto error;
		}
	} else {
		memset(&msg_2_2, 0, sizeof(msg_2_2));
		/* Compat with relayd 2.2+ */
		if (lttng_strncpy(msg_2_2.channel_name, channel_name,
				sizeof(msg_2_2.channel_name))) {
			ret = -1;
			goto error;
		}
		if (lttng_strncpy(msg_2_2.pathname, pathname,
				sizeof(msg_2_2.pathname))) {
			ret = -1;
			goto error;
		}
		msg_2_2.tracefile_size = htobe64(tracefile_size);
		msg_2_2.tracefile_count = htobe64(tracefile_count);

		/* Send command */
		ret = send_command(rsock, RELAYD_ADD_STREAM, (void *) &msg_2_2, sizeof(msg_2_2), 0);
		if (ret < 0) {
			goto error;
		}
	}

	DBG("Relayd add stream sent for channel name %s.", channel_name);
	ret = 0;

error:
	return ret;
}

int relayd_add_stream_rcv(struct lttcomm_relayd_sock *rsock, uint64_t *_stream_id)
{
	int ret;
	struct lttcomm_relayd_status_stream reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	/* Waiting for reply */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	/* Back to host bytes order. */
	reply.handle = be64toh(reply.handle);
	reply.ret_code = be32toh(reply.ret_code);

	/* Return session id or negative ret code. */
	if (reply.ret_code != LTTNG_OK) {
		ret = -1;
		ERR("Relayd add stream replied error %d", reply.ret_code);
	} else {
		/* Success */
		ret = 0;
		*_stream_id = reply.handle;
	}

	DBG("Relayd stream added successfully with handle %" PRIu64,
		reply.handle);

error:
	return ret;
}

/*
 * Inform the relay that all the streams for the current channel has been sent.
 *
 * On success return 0 else return ret_code negative value.
 */
int relayd_streams_sent(struct lttcomm_relayd_sock *rsock)
{
	int ret;
	struct lttcomm_relayd_generic_reply reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	DBG("Relayd sending streams sent.");

	/* This feature was introduced in 2.4, ignore it for earlier versions. */
	if (rsock->minor < 4) {
		ret = 0;
		goto end;
	}

	/* Send command */
	ret = send_command(rsock, RELAYD_STREAMS_SENT, NULL, 0, 0);
	if (ret < 0) {
		goto error;
	}

	/* Waiting for reply */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	/* Back to host bytes order. */
	reply.ret_code = be32toh(reply.ret_code);

	/* Return session id or negative ret code. */
	if (reply.ret_code != LTTNG_OK) {
		ret = -1;
		ERR("Relayd streams sent replied error %d", reply.ret_code);
		goto error;
	} else {
		/* Success */
		ret = 0;
	}

	DBG("Relayd streams sent success");

error:
end:
	return ret;
}

/*
 * Check version numbers on the relayd.
 * If major versions are compatible, we assign minor_to_use to the
 * minor version of the procotol we are going to use for this session.
 *
 * Return 0 if the two daemons are compatible, LTTNG_ERR_RELAYD_VERSION_FAIL
 * otherwise, or a negative value on network errors.
 */
int relayd_version_check(struct lttcomm_relayd_sock *rsock)
{
	int ret;
	struct lttcomm_relayd_version msg;

	/* Code flow error. Safety net. */
	assert(rsock);

	DBG("Relayd version check for major.minor %u.%u", rsock->major,
			rsock->minor);

	memset(&msg, 0, sizeof(msg));
	/* Prepare network byte order before transmission. */
	msg.major = htobe32(rsock->major);
	msg.minor = htobe32(rsock->minor);

	/* Send command */
	ret = send_command(rsock, RELAYD_VERSION, (void *) &msg, sizeof(msg), 0);
	if (ret < 0) {
		goto error;
	}

	/* Receive response */
	ret = recv_reply(rsock, (void *) &msg, sizeof(msg));
	if (ret < 0) {
		goto error;
	}

	/* Set back to host bytes order */
	msg.major = be32toh(msg.major);
	msg.minor = be32toh(msg.minor);

	/*
	 * Only validate the major version. If the other side is higher,
	 * communication is not possible. Only major version equal can talk to each
	 * other. If the minor version differs, the lowest version is used by both
	 * sides.
	 */
	if (msg.major != rsock->major) {
		/* Not compatible */
		ret = LTTNG_ERR_RELAYD_VERSION_FAIL;
		DBG2("Relayd version is NOT compatible. Relayd version %u != %u (us)",
				msg.major, rsock->major);
		goto error;
	}

	/*
	 * If the relayd's minor version is higher, it will adapt to our version so
	 * we can continue to use the latest relayd communication data structure.
	 * If the received minor version is higher, the relayd should adapt to us.
	 */
	if (rsock->minor > msg.minor) {
		rsock->minor = msg.minor;
	}

	/* Version number compatible */
	DBG2("Relayd version is compatible, using protocol version %u.%u",
			rsock->major, rsock->minor);
	ret = 0;

error:
	return ret;
}

/*
 * Add stream on the relayd and assign stream handle to the stream_id argument.
 *
 * On success return 0 else return ret_code negative value.
 */
int relayd_send_metadata(struct lttcomm_relayd_sock *rsock, size_t len)
{
	int ret;

	/* Code flow error. Safety net. */
	assert(rsock);

	DBG("Relayd sending metadata of size %zu", len);

	/* Send command */
	ret = send_command(rsock, RELAYD_SEND_METADATA, NULL, len, 0);
	if (ret < 0) {
		goto error;
	}

	DBG2("Relayd metadata added successfully");

	/*
	 * After that call, the metadata data MUST be sent to the relayd so the
	 * receive size on the other end matches the len of the metadata packet
	 * header. This is why we don't wait for a reply here.
	 */

error:
	return ret;
}

/*
 * Connect to relay daemon with an allocated lttcomm_relayd_sock.
 */
int relayd_connect(struct lttcomm_relayd_sock *rsock)
{
	/* Code flow error. Safety net. */
	assert(rsock);

	if (!rsock->sock.ops) {
		/*
		 * Attempting a connect on a non-initialized socket.
		 */
		return -ECONNRESET;
	}

	DBG3("Relayd connect ...");

	return rsock->sock.ops->connect(&rsock->sock);
}

/*
 * Close relayd socket with an allocated lttcomm_relayd_sock.
 *
 * If no socket operations are found, simply return 0 meaning that everything
 * is fine. Without operations, the socket can not possibly be opened or used.
 * This is possible if the socket was allocated but not created. However, the
 * caller could simply use it to store a valid file descriptor for instance
 * passed over a Unix socket and call this to cleanup but still without a valid
 * ops pointer.
 *
 * Return the close returned value. On error, a negative value is usually
 * returned back from close(2).
 */
int relayd_close(struct lttcomm_relayd_sock *rsock)
{
	int ret;

	/* Code flow error. Safety net. */
	assert(rsock);

	/* An invalid fd is fine, return success. */
	if (rsock->sock.fd < 0) {
		ret = 0;
		goto end;
	}

	/*
	 * This ensure that we do not close the socket while the lttng-relayd
	 * expects to be able to send a response that we skipped.
	 * While we loose some time to receive everything, this keep the
	 * protocol intact from the point of view of lttng-relayd.
	 */
	if (rsock->bytes_to_ignore_on_recv != 0) {
		ret = rsock->sock.ops->recvmsg(&rsock->sock, NULL, rsock->bytes_to_ignore_on_recv, MSG_TRUNC);
		if (ret <= 0 || ret != rsock->bytes_to_ignore_on_recv) {
			if (ret == 0) {
				/* Orderly shutdown. */
				DBG("Socket %d has performed an orderly shutdown", rsock->sock.fd);
			} else {
				DBG("Receiving reply to skip failed on sock %d for size %zu with ret %d",
						rsock->sock.fd, rsock->bytes_to_ignore_on_recv, ret);
			}
		}
		DBG("Discarded %zu bytes on sock %d", rsock->bytes_to_ignore_on_recv, rsock->sock.fd);
		rsock->bytes_to_ignore_on_recv = 0;
	}

	DBG3("Relayd closing socket %d", rsock->sock.fd);

	if (rsock->sock.ops) {
		ret = rsock->sock.ops->close(&rsock->sock);
	} else {
		/* Default call if no specific ops found. */
		ret = close(rsock->sock.fd);
		if (ret < 0) {
			PERROR("relayd_close default close");
		}
	}
	rsock->sock.fd = -1;

end:
	return ret;
}

/*
 * Send data header structure to the relayd.
 */
int relayd_send_data_hdr(struct lttcomm_relayd_sock *rsock,
		struct lttcomm_relayd_data_hdr *hdr, size_t size)
{
	int ret;

	/* Code flow error. Safety net. */
	assert(rsock);
	assert(hdr);

	if (rsock->sock.fd < 0) {
		return -ECONNRESET;
	}

	DBG3("Relayd sending data header of size %zu", size);

	/* Again, safety net */
	if (size == 0) {
		size = sizeof(struct lttcomm_relayd_data_hdr);
	}

	/* Only send data header. */
	ret = rsock->sock.ops->sendmsg(&rsock->sock, hdr, size, 0);
	if (ret < 0) {
		ret = -errno;
		goto error;
	}

	/*
	 * The data MUST be sent right after that command for the receive on the
	 * other end to match the size in the header.
	 */

error:
	return ret;
}

/*
 * Send close stream command to the relayd.
 */
int relayd_send_close_stream(struct lttcomm_relayd_sock *rsock, uint64_t stream_id,
		uint64_t last_net_seq_num)
{
	int ret;
	struct lttcomm_relayd_close_stream msg;
	struct lttcomm_relayd_generic_reply reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	DBG("Relayd closing stream id %" PRIu64, stream_id);

	memset(&msg, 0, sizeof(msg));
	msg.stream_id = htobe64(stream_id);
	msg.last_net_seq_num = htobe64(last_net_seq_num);

	/* Send command */
	ret = send_command(rsock, RELAYD_CLOSE_STREAM, (void *) &msg, sizeof(msg), 0);
	if (ret < 0) {
		goto error;
	}

	/*
	 * Discard response since we do not really care for it and that TCP
	 * guarantee in-order delivery. As for error handling, there is not much
	 * to do at this point (closing).
	 **/
	ret = recv_reply_ignore(rsock, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	DBG("Relayd close stream id %" PRIu64 " successfully", stream_id);

error:
	return ret;
}

/*
 * Check for data availability for a given stream id.
 *
 * Return 0 if NOT pending, 1 if so and a negative value on error.
 */
int relayd_data_pending(struct lttcomm_relayd_sock *rsock, uint64_t stream_id,
		uint64_t last_net_seq_num)
{
	int ret;
	struct lttcomm_relayd_data_pending msg;
	struct lttcomm_relayd_generic_reply reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	DBG("Relayd data pending for stream id %" PRIu64, stream_id);

	memset(&msg, 0, sizeof(msg));
	msg.stream_id = htobe64(stream_id);
	msg.last_net_seq_num = htobe64(last_net_seq_num);

	/* Send command */
	ret = send_command(rsock, RELAYD_DATA_PENDING, (void *) &msg,
			sizeof(msg), 0);
	if (ret < 0) {
		goto error;
	}

	/* Receive response */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	reply.ret_code = be32toh(reply.ret_code);

	/* Return session id or negative ret code. */
	if (reply.ret_code >= LTTNG_OK) {
		ERR("Relayd data pending replied error %d", reply.ret_code);
	}

	/* At this point, the ret code is either 1 or 0 */
	ret = reply.ret_code;

	DBG("Relayd data is %s pending for stream id %" PRIu64,
			ret == 1 ? "" : "NOT", stream_id);

error:
	return ret;
}

/*
 * Check on the relayd side for a quiescent state on the control socket.
 */
int relayd_quiescent_control(struct lttcomm_relayd_sock *rsock,
		uint64_t metadata_stream_id)
{
	int ret;
	struct lttcomm_relayd_quiescent_control msg;
	struct lttcomm_relayd_generic_reply reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	DBG("Relayd checking quiescent control state");

	memset(&msg, 0, sizeof(msg));
	msg.stream_id = htobe64(metadata_stream_id);

	/* Send command */
	ret = send_command(rsock, RELAYD_QUIESCENT_CONTROL, &msg, sizeof(msg), 0);
	if (ret < 0) {
		goto error;
	}

	/* Receive response */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	reply.ret_code = be32toh(reply.ret_code);

	/* Return session id or negative ret code. */
	if (reply.ret_code != LTTNG_OK) {
		ret = -1;
		ERR("Relayd quiescent control replied error %d", reply.ret_code);
		goto error;
	}

	/* Control socket is quiescent */
	return 0;

error:
	return ret;
}

/*
 * Begin a data pending command for a specific session id.
 */
int relayd_begin_data_pending(struct lttcomm_relayd_sock *rsock, uint64_t id)
{
	int ret;
	struct lttcomm_relayd_begin_data_pending msg;
	struct lttcomm_relayd_generic_reply reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	DBG("Relayd begin data pending");

	memset(&msg, 0, sizeof(msg));
	msg.session_id = htobe64(id);

	/* Send command */
	ret = send_command(rsock, RELAYD_BEGIN_DATA_PENDING, &msg, sizeof(msg), 0);
	if (ret < 0) {
		goto error;
	}

	/* Receive response */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	reply.ret_code = be32toh(reply.ret_code);

	/* Return session id or negative ret code. */
	if (reply.ret_code != LTTNG_OK) {
		ret = -1;
		ERR("Relayd begin data pending replied error %d", reply.ret_code);
		goto error;
	}

	return 0;

error:
	return ret;
}

/*
 * End a data pending command for a specific session id.
 *
 * Return 0 on success and set is_data_inflight to 0 if no data is being
 * streamed or 1 if it is the case.
 */
int relayd_end_data_pending(struct lttcomm_relayd_sock *rsock, uint64_t id,
		unsigned int *is_data_inflight)
{
	int ret, recv_ret;
	struct lttcomm_relayd_end_data_pending msg;
	struct lttcomm_relayd_generic_reply reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	DBG("Relayd end data pending");

	memset(&msg, 0, sizeof(msg));
	msg.session_id = htobe64(id);

	/* Send command */
	ret = send_command(rsock, RELAYD_END_DATA_PENDING, &msg, sizeof(msg), 0);
	if (ret < 0) {
		goto error;
	}

	/* Receive response */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	recv_ret = be32toh(reply.ret_code);
	if (recv_ret < 0) {
		ret = recv_ret;
		goto error;
	}

	*is_data_inflight = recv_ret;

	DBG("Relayd end data pending is data inflight: %d", recv_ret);

	return 0;

error:
	return ret;
}

/*
 * Send index to the relayd.
 */
int relayd_send_index(struct lttcomm_relayd_sock *rsock,
		struct ctf_packet_index *index, uint64_t relay_stream_id,
		uint64_t net_seq_num)
{
	int ret;
	struct lttcomm_relayd_index msg;
	struct lttcomm_relayd_generic_reply reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	if (rsock->minor < 4) {
		DBG("Not sending indexes before protocol 2.4");
		ret = 0;
		goto error;
	}

	DBG("Relayd sending index for stream ID %" PRIu64, relay_stream_id);

	memset(&msg, 0, sizeof(msg));
	msg.relay_stream_id = htobe64(relay_stream_id);
	msg.net_seq_num = htobe64(net_seq_num);

	/* The index is already in big endian. */
	msg.packet_size = index->packet_size;
	msg.content_size = index->content_size;
	msg.timestamp_begin = index->timestamp_begin;
	msg.timestamp_end = index->timestamp_end;
	msg.events_discarded = index->events_discarded;
	msg.stream_id = index->stream_id;

	if (rsock->minor >= 8) {
		msg.stream_instance_id = index->stream_instance_id;
		msg.packet_seq_num = index->packet_seq_num;
	}

	/* Send command */
	ret = send_command(rsock, RELAYD_SEND_INDEX, &msg,
		lttcomm_relayd_index_len(lttng_to_index_major(rsock->major,
								rsock->minor),
				lttng_to_index_minor(rsock->major, rsock->minor)),
				0);
	if (ret < 0) {
		goto error;
	}

	/*
	 * Ignore the response. TCP guarantee in-order arrival and the overall
	 * protocol do not rely on hard ordering between the control and data
	 * socket for index.
	 * Indexes are sent either at the end of the buffer consumption or
	 * during the live timer.
	 */
	ret = recv_reply_ignore(rsock, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

error:
	return ret;
}

/*
 * Ask the relay to reset the metadata trace file (regeneration).
 */
int relayd_reset_metadata(struct lttcomm_relayd_sock *rsock,
		uint64_t stream_id, uint64_t version)
{
	int ret;
	struct lttcomm_relayd_reset_metadata msg;
	struct lttcomm_relayd_generic_reply reply;

	/* Code flow error. Safety net. */
	assert(rsock);

	/* Should have been prevented by the sessiond. */
	if (rsock->minor < 8) {
		ERR("Metadata regeneration unsupported before 2.8");
		ret = -1;
		goto error;
	}

	DBG("Relayd reset metadata stream id %" PRIu64, stream_id);

	memset(&msg, 0, sizeof(msg));
	msg.stream_id = htobe64(stream_id);
	msg.version = htobe64(version);

	/* Send command */
	ret = send_command(rsock, RELAYD_RESET_METADATA, (void *) &msg, sizeof(msg), 0);
	if (ret < 0) {
		goto error;
	}

	/* Receive response */
	ret = recv_reply(rsock, (void *) &reply, sizeof(reply));
	if (ret < 0) {
		goto error;
	}

	reply.ret_code = be32toh(reply.ret_code);

	/* Return session id or negative ret code. */
	if (reply.ret_code != LTTNG_OK) {
		ret = -1;
		ERR("Relayd reset metadata replied error %d", reply.ret_code);
	} else {
		/* Success */
		ret = 0;
	}

	DBG("Relayd reset metadata stream id %" PRIu64 " successfully", stream_id);

error:
	return ret;
}