Fix: src.ctf.lttng-live: `fwrite()` does not set `errno`

[babeltrace.git] / src / plugins / ctf / lttng-live / viewer-connection.c

/*
 * Copyright 2019 - Francis Deslauriers <francis.deslauriers@efficios.com>
 * Copyright 2016 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#define BT_COMP_LOG_SELF_COMP (viewer_connection->self_comp)
#define BT_LOG_OUTPUT_LEVEL (viewer_connection->log_level)
#define BT_LOG_TAG "PLUGIN/SRC.CTF.LTTNG-LIVE/VIEWER"
#include "logging/comp-logging.h"

#include <fcntl.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

#include <glib.h>

#include "compat/socket.h"
#include "compat/endian.h"
#include "compat/compiler.h"
#include "common/common.h"
#include <babeltrace2/babeltrace.h>

#include "lttng-live.h"
#include "viewer-connection.h"
#include "lttng-viewer-abi.h"
#include "data-stream.h"
#include "metadata.h"

#define viewer_handle_send_recv_status(_self_comp, _self_comp_class,    \
                _status, _action, _msg_str)                             \
do {                                                                    \
        switch (_status) {                                              \
        case LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED:                      \
                break;                                                  \
        case LTTNG_LIVE_VIEWER_STATUS_ERROR:                            \
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(_self_comp,     \
                        _self_comp_class, "Error " _action " " _msg_str); \
                break;                                                  \
        default:                                                        \
                 bt_common_abort();                                     \
        }                                                               \
} while (0)

#define viewer_handle_send_status(_self_comp, _self_comp_class, _status, _msg_str) \
        viewer_handle_send_recv_status(_self_comp, _self_comp_class, _status, \
                "sending", _msg_str)

#define viewer_handle_recv_status(_self_comp, _self_comp_class, _status, _msg_str) \
        viewer_handle_send_recv_status(_self_comp, _self_comp_class, _status, \
                "receiving", _msg_str)

#define LTTNG_LIVE_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE_ERRNO(_self_comp, \
                _self_comp_class, _msg, _fmt, ...) \
        do {                                                                            \
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(_self_comp, _self_comp_class,   \
                        _msg ": %s" _fmt, bt_socket_errormsg(), ##__VA_ARGS__);         \
        } while (0)

static inline
enum lttng_live_iterator_status viewer_status_to_live_iterator_status(
                enum lttng_live_viewer_status viewer_status)
{
        switch (viewer_status) {
        case LTTNG_LIVE_VIEWER_STATUS_OK:
                return LTTNG_LIVE_ITERATOR_STATUS_OK;
        case LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED:
                return LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
        case LTTNG_LIVE_VIEWER_STATUS_ERROR:
                return LTTNG_LIVE_ITERATOR_STATUS_ERROR;
        default:
                bt_common_abort();
        }
}

static inline
enum ctf_msg_iter_medium_status viewer_status_to_ctf_msg_iter_medium_status(
                enum lttng_live_viewer_status viewer_status)
{
        switch (viewer_status) {
        case LTTNG_LIVE_VIEWER_STATUS_OK:
                return CTF_MSG_ITER_MEDIUM_STATUS_OK;
        case LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED:
                return CTF_MSG_ITER_MEDIUM_STATUS_AGAIN;
        case LTTNG_LIVE_VIEWER_STATUS_ERROR:
                return CTF_MSG_ITER_MEDIUM_STATUS_ERROR;
        default:
                bt_common_abort();
        }
}

static inline
void viewer_connection_close_socket(
                struct live_viewer_connection *viewer_connection)
{
        bt_self_component_class *self_comp_class =
                viewer_connection->self_comp_class;
        bt_self_component *self_comp =
                viewer_connection->self_comp;
        int ret = bt_socket_close(viewer_connection->control_sock);
        if (ret == -1) {
                BT_COMP_OR_COMP_CLASS_LOGW_ERRNO(
                        self_comp, self_comp_class,
                        "Error closing viewer connection socket: ", ".");
        }

        viewer_connection->control_sock = BT_INVALID_SOCKET;
}

/*
 * This function receives a message from the Relay daemon.
 * If it received the entire message, it returns _OK,
 * If it's interrupted, it returns _INTERRUPTED,
 * otherwise, it returns _ERROR.
 */
static
enum lttng_live_viewer_status lttng_live_recv(
                struct live_viewer_connection *viewer_connection,
                void *buf, size_t len)
{
        ssize_t received;
        bt_self_component_class *self_comp_class =
                viewer_connection->self_comp_class;
        bt_self_component *self_comp =
                viewer_connection->self_comp;
        size_t total_received = 0, to_receive = len;
        struct lttng_live_msg_iter *lttng_live_msg_iter =
                viewer_connection->lttng_live_msg_iter;
        enum lttng_live_viewer_status status;
        BT_SOCKET sock = viewer_connection->control_sock;

        /*
         * Receive a message from the Relay.
         */
        do {
                received = bt_socket_recv(sock, buf + total_received, to_receive, 0);
                if (received == BT_SOCKET_ERROR) {
                        if (bt_socket_interrupted()) {
                                if (lttng_live_graph_is_canceled(lttng_live_msg_iter)) {
                                        /*
                                         * This interruption was due to a
                                         * SIGINT and the graph is being torn
                                         * down.
                                         */
                                        status = LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED;
                                        lttng_live_msg_iter->was_interrupted = true;
                                        goto end;
                                } else {
                                        /*
                                         * A signal was received, but the graph
                                         * is not being torn down. Carry on.
                                         */
                                        continue;
                                }
                        } else {
                                /*
                                 * For any other types of socket error, close
                                 * the socket and return an error.
                                 */
                                LTTNG_LIVE_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE_ERRNO(
                                        self_comp, self_comp_class,
                                        "Error receiving from Relay", ".");

                                viewer_connection_close_socket(viewer_connection);
                                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                                goto end;
                        }
                } else if (received == 0) {
                        /*
                         * The recv() call returned 0. This means the
                         * connection was orderly shutdown from the other peer.
                         * If that happens when we are trying to receive
                         * a message from it, it means something when wrong.
                         * Close the socket and return an error.
                         */
                        BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                                self_comp_class, "Remote side has closed connection");
                        viewer_connection_close_socket(viewer_connection);
                        status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                        goto end;
                }

                BT_ASSERT(received <= to_receive);
                total_received += received;
                to_receive -= received;

        } while (to_receive > 0);

        BT_ASSERT(total_received == len);
        status = LTTNG_LIVE_VIEWER_STATUS_OK;

end:
        return status;
}

/*
 * This function sends a message to the Relay daemon.
 * If it send the message, it returns _OK,
 * If it's interrupted, it returns _INTERRUPTED,
 * otherwise, it returns _ERROR.
 */
static
enum lttng_live_viewer_status lttng_live_send(
                struct live_viewer_connection *viewer_connection,
                const void *buf, size_t len)
{
        enum lttng_live_viewer_status status;
        bt_self_component_class *self_comp_class =
                viewer_connection->self_comp_class;
        bt_self_component *self_comp =
                viewer_connection->self_comp;
        struct lttng_live_msg_iter *lttng_live_msg_iter =
                viewer_connection->lttng_live_msg_iter;
        BT_SOCKET sock = viewer_connection->control_sock;
        size_t to_send = len;
        ssize_t total_sent = 0;

        do {
                ssize_t sent = bt_socket_send_nosigpipe(sock, buf + total_sent,
                        to_send);
                if (sent == BT_SOCKET_ERROR) {
                        if (bt_socket_interrupted()) {
                                if (lttng_live_graph_is_canceled(lttng_live_msg_iter)) {
                                        /*
                                         * This interruption was a SIGINT and
                                         * the graph is being teared down.
                                         */
                                        status = LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED;
                                        lttng_live_msg_iter->was_interrupted = true;
                                        goto end;
                                } else {
                                        /*
                                         * A signal was received, but the graph
                                         * is not being teared down. Carry on.
                                         */
                                        continue;
                                }
                        } else {
                                /*
                                 * For any other types of socket error, close
                                 * the socket and return an error.
                                 */
                                LTTNG_LIVE_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE_ERRNO(
                                        self_comp, self_comp_class,
                                        "Error sending to Relay", ".");

                                viewer_connection_close_socket(viewer_connection);
                                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                                goto end;
                        }
                }

                BT_ASSERT(sent <= to_send);
                total_sent += sent;
                to_send -= sent;

        } while (to_send > 0);

        BT_ASSERT(total_sent == len);
        status = LTTNG_LIVE_VIEWER_STATUS_OK;

end:
        return status;
}

static
int parse_url(struct live_viewer_connection *viewer_connection)
{
        char error_buf[256] = { 0 };
        bt_self_component *self_comp = viewer_connection->self_comp;
        bt_self_component_class *self_comp_class = viewer_connection->self_comp_class;
        struct bt_common_lttng_live_url_parts lttng_live_url_parts = { 0 };
        int ret = -1;
        const char *path = viewer_connection->url->str;

        if (!path) {
                goto end;
        }

        lttng_live_url_parts = bt_common_parse_lttng_live_url(path, error_buf,
                sizeof(error_buf));
        if (!lttng_live_url_parts.proto) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class,"Invalid LTTng live URL format: %s",
                        error_buf);
                goto end;
        }
        viewer_connection->proto = lttng_live_url_parts.proto;
        lttng_live_url_parts.proto = NULL;

        viewer_connection->relay_hostname = lttng_live_url_parts.hostname;
        lttng_live_url_parts.hostname = NULL;

        if (lttng_live_url_parts.port >= 0) {
                viewer_connection->port = lttng_live_url_parts.port;
        } else {
                viewer_connection->port = LTTNG_DEFAULT_NETWORK_VIEWER_PORT;
        }

        viewer_connection->target_hostname = lttng_live_url_parts.target_hostname;
        lttng_live_url_parts.target_hostname = NULL;

        if (lttng_live_url_parts.session_name) {
                viewer_connection->session_name = lttng_live_url_parts.session_name;
                lttng_live_url_parts.session_name = NULL;
        }

        ret = 0;

end:
        bt_common_destroy_lttng_live_url_parts(&lttng_live_url_parts);
        return ret;
}

static
enum lttng_live_viewer_status lttng_live_handshake(
                struct live_viewer_connection *viewer_connection)
{
        struct lttng_viewer_cmd cmd;
        struct lttng_viewer_connect connect;
        enum lttng_live_viewer_status status;
        bt_self_component_class *self_comp_class = viewer_connection->self_comp_class;
        bt_self_component *self_comp = viewer_connection->self_comp;
        const size_t cmd_buf_len = sizeof(cmd) + sizeof(connect);
        char cmd_buf[cmd_buf_len];

        BT_COMP_OR_COMP_CLASS_LOGD(self_comp, self_comp_class,
                "Handshaking with the Relay: "
                "major-version=%u, minor-version=%u",
                LTTNG_LIVE_MAJOR, LTTNG_LIVE_MINOR);

        cmd.cmd = htobe32(LTTNG_VIEWER_CONNECT);
        cmd.data_size = htobe64((uint64_t) sizeof(connect));
        cmd.cmd_version = htobe32(0);

        connect.viewer_session_id = -1ULL;      /* will be set on recv */
        connect.major = htobe32(LTTNG_LIVE_MAJOR);
        connect.minor = htobe32(LTTNG_LIVE_MINOR);
        connect.type = htobe32(LTTNG_VIEWER_CLIENT_COMMAND);

        /*
         * Merge the cmd and connection request to prevent a write-write
         * sequence on the TCP socket. Otherwise, a delayed ACK will prevent the
         * second write to be performed quickly in presence of Nagle's algorithm
         */
        memcpy(cmd_buf, &cmd, sizeof(cmd));
        memcpy(cmd_buf + sizeof(cmd), &connect, sizeof(connect));

        status = lttng_live_send(viewer_connection, &cmd_buf, cmd_buf_len);
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, self_comp_class,
                        status, "viewer connect command");
                goto end;
        }

        status = lttng_live_recv(viewer_connection, &connect, sizeof(connect));
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, self_comp_class,
                        status, "viewer connect reply");
                goto end;
        }

        BT_COMP_OR_COMP_CLASS_LOGI(self_comp, self_comp_class,
                "Received viewer session ID : %" PRIu64,
                (uint64_t) be64toh(connect.viewer_session_id));
        BT_COMP_OR_COMP_CLASS_LOGI(self_comp, self_comp_class,
                "Relayd version : %u.%u", be32toh(connect.major),
                be32toh(connect.minor));

        if (LTTNG_LIVE_MAJOR != be32toh(connect.major)) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Incompatible lttng-relayd protocol");
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        }
        /* Use the smallest protocol version implemented. */
        if (LTTNG_LIVE_MINOR > be32toh(connect.minor)) {
                viewer_connection->minor =  be32toh(connect.minor);
        } else {
                viewer_connection->minor =  LTTNG_LIVE_MINOR;
        }
        viewer_connection->major = LTTNG_LIVE_MAJOR;

        status = LTTNG_LIVE_VIEWER_STATUS_OK;

        goto end;

end:
        return status;
}

static
enum lttng_live_viewer_status lttng_live_connect_viewer(
        struct live_viewer_connection *viewer_connection)
{
        struct hostent *host;
        struct sockaddr_in server_addr;
        enum lttng_live_viewer_status status;
        bt_self_component_class *self_comp_class = viewer_connection->self_comp_class;
        bt_self_component *self_comp = viewer_connection->self_comp;

        if (parse_url(viewer_connection)) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Failed to parse URL");
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto error;
        }

        BT_COMP_OR_COMP_CLASS_LOGD(self_comp, self_comp_class,
                "Connecting to hostname : %s, port : %d, "
                "target hostname : %s, session name : %s, proto : %s",
                viewer_connection->relay_hostname->str,
                viewer_connection->port,
                !viewer_connection->target_hostname ?
                "<none>" : viewer_connection->target_hostname->str,
                !viewer_connection->session_name ?
                "<none>" : viewer_connection->session_name->str,
                viewer_connection->proto->str);

        host = gethostbyname(viewer_connection->relay_hostname->str);
        if (!host) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Cannot lookup hostname: hostname=\"%s\"",
                        viewer_connection->relay_hostname->str);
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto error;
        }

        if ((viewer_connection->control_sock = socket(AF_INET, SOCK_STREAM, 0)) == BT_INVALID_SOCKET) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Socket creation failed: %s", bt_socket_errormsg());
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto error;
        }

        server_addr.sin_family = AF_INET;
        server_addr.sin_port = htons(viewer_connection->port);
        server_addr.sin_addr = *((struct in_addr *) host->h_addr);
        memset(&(server_addr.sin_zero), 0, 8);

        if (connect(viewer_connection->control_sock, (struct sockaddr *) &server_addr,
                                sizeof(struct sockaddr)) == BT_SOCKET_ERROR) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Connection failed: %s",
                        bt_socket_errormsg());
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto error;
        }

        status = lttng_live_handshake(viewer_connection);

        /*
         * Only print error and append cause in case of error. not in case of
         * interruption.
         */
        if (status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Viewer handshake failed");
                goto error;
        } else if (status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
                goto end;
        }

        goto end;

error:
        if (viewer_connection->control_sock != BT_INVALID_SOCKET) {
                if (bt_socket_close(viewer_connection->control_sock) == BT_SOCKET_ERROR) {
                        BT_COMP_OR_COMP_CLASS_LOGW(self_comp, self_comp_class,
                                "Error closing socket: %s.", bt_socket_errormsg());
                }
        }
        viewer_connection->control_sock = BT_INVALID_SOCKET;
end:
        return status;
}

static
void lttng_live_disconnect_viewer(
                struct live_viewer_connection *viewer_connection)
{
        bt_self_component_class *self_comp_class = viewer_connection->self_comp_class;
        bt_self_component *self_comp = viewer_connection->self_comp;

        if (viewer_connection->control_sock == BT_INVALID_SOCKET) {
                return;
        }
        if (bt_socket_close(viewer_connection->control_sock) == BT_SOCKET_ERROR) {
                BT_COMP_OR_COMP_CLASS_LOGW(self_comp, self_comp_class,
                        "Error closing socket: %s", bt_socket_errormsg());
                viewer_connection->control_sock = BT_INVALID_SOCKET;
        }
}

static
int list_update_session(bt_value *results,
                const struct lttng_viewer_session *session,
                bool *_found, struct live_viewer_connection *viewer_connection)
{
        bt_self_component_class *self_comp_class = viewer_connection->self_comp_class;
        bt_self_component *self_comp = viewer_connection->self_comp;
        int ret = 0;
        uint64_t i, len;
        bt_value *map = NULL;
        bt_value *hostname = NULL;
        bt_value *session_name = NULL;
        bt_value *btval = NULL;
        bool found = false;

        len = bt_value_array_get_length(results);
        for (i = 0; i < len; i++) {
                const char *hostname_str = NULL;
                const char *session_name_str = NULL;

                map = bt_value_array_borrow_element_by_index(results, i);
                hostname = bt_value_map_borrow_entry_value(map, "target-hostname");
                if (!hostname) {
                        BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                                self_comp_class,
                                "Error borrowing \"target-hostname\" entry.");
                        ret = -1;
                        goto end;
                }
                session_name = bt_value_map_borrow_entry_value(map, "session-name");
                if (!session_name) {
                        BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                                self_comp_class,
                                "Error borrowing \"session-name\" entry.");
                        ret = -1;
                        goto end;
                }
                hostname_str = bt_value_string_get(hostname);
                session_name_str = bt_value_string_get(session_name);

                if (strcmp(session->hostname, hostname_str) == 0
                                && strcmp(session->session_name, session_name_str) == 0) {
                        int64_t val;
                        uint32_t streams = be32toh(session->streams);
                        uint32_t clients = be32toh(session->clients);

                        found = true;

                        btval = bt_value_map_borrow_entry_value(map, "stream-count");
                        if (!btval) {
                                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(
                                        self_comp, self_comp_class,
                                        "Error borrowing \"stream-count\" entry.");
                                ret = -1;
                                goto end;
                        }
                        val = bt_value_integer_unsigned_get(btval);
                        /* sum */
                        val += streams;
                        bt_value_integer_unsigned_set(btval, val);

                        btval = bt_value_map_borrow_entry_value(map, "client-count");
                        if (!btval) {
                                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(
                                        self_comp, self_comp_class,
                                        "Error borrowing \"client-count\" entry.");
                                ret = -1;
                                goto end;
                        }
                        val = bt_value_integer_unsigned_get(btval);
                        /* max */
                        val = bt_max_t(int64_t, clients, val);
                        bt_value_integer_unsigned_set(btval, val);
                }

                if (found) {
                        break;
                }
        }
end:
        *_found = found;
        return ret;
}

static
int list_append_session(bt_value *results,
                GString *base_url,
                const struct lttng_viewer_session *session,
                struct live_viewer_connection *viewer_connection)
{
        int ret = 0;
        bt_self_component_class *self_comp_class = viewer_connection->self_comp_class;
        bt_value_map_insert_entry_status insert_status;
        bt_value_array_append_element_status append_status;
        bt_value *map = NULL;
        GString *url = NULL;
        bool found = false;

        /*
         * If the session already exists, add the stream count to it,
         * and do max of client counts.
         */
        ret = list_update_session(results, session, &found, viewer_connection);
        if (ret || found) {
                goto end;
        }

        map = bt_value_map_create();
        if (!map) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error creating map value.");
                ret = -1;
                goto end;
        }

        if (base_url->len < 1) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error: base_url length smaller than 1.");
                ret = -1;
                goto end;
        }
        /*
         * key = "url",
         * value = <string>,
         */
        url = g_string_new(base_url->str);
        g_string_append(url, "/host/");
        g_string_append(url, session->hostname);
        g_string_append_c(url, '/');
        g_string_append(url, session->session_name);

        insert_status = bt_value_map_insert_string_entry(map, "url", url->str);
        if (insert_status != BT_VALUE_MAP_INSERT_ENTRY_STATUS_OK) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error inserting \"url\" entry.");
                ret = -1;
                goto end;
        }

        /*
         * key = "target-hostname",
         * value = <string>,
         */
        insert_status = bt_value_map_insert_string_entry(map, "target-hostname",
                session->hostname);
        if (insert_status != BT_VALUE_MAP_INSERT_ENTRY_STATUS_OK) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error inserting \"target-hostname\" entry.");
                ret = -1;
                goto end;
        }

        /*
         * key = "session-name",
         * value = <string>,
         */
        insert_status = bt_value_map_insert_string_entry(map, "session-name",
                session->session_name);
        if (insert_status != BT_VALUE_MAP_INSERT_ENTRY_STATUS_OK) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error inserting \"session-name\" entry.");
                ret = -1;
                goto end;
        }

        /*
         * key = "timer-us",
         * value = <integer>,
         */
        {
                uint32_t live_timer = be32toh(session->live_timer);

                insert_status = bt_value_map_insert_unsigned_integer_entry(
                        map, "timer-us", live_timer);
                if (insert_status != BT_VALUE_MAP_INSERT_ENTRY_STATUS_OK) {
                        BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                                "Error inserting \"timer-us\" entry.");
                        ret = -1;
                        goto end;
                }
        }

        /*
         * key = "stream-count",
         * value = <integer>,
         */
        {
                uint32_t streams = be32toh(session->streams);

                insert_status = bt_value_map_insert_unsigned_integer_entry(map,
                        "stream-count", streams);
                if (insert_status != BT_VALUE_MAP_INSERT_ENTRY_STATUS_OK) {
                        BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                                "Error inserting \"stream-count\" entry.");
                        ret = -1;
                        goto end;
                }
        }

        /*
         * key = "client-count",
         * value = <integer>,
         */
        {
                uint32_t clients = be32toh(session->clients);

                insert_status = bt_value_map_insert_unsigned_integer_entry(map,
                        "client-count", clients);
                if (insert_status != BT_VALUE_MAP_INSERT_ENTRY_STATUS_OK) {
                        BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                                "Error inserting \"client-count\" entry.");
                        ret = -1;
                        goto end;
                }
        }

        append_status = bt_value_array_append_element(results, map);
        if (append_status != BT_VALUE_ARRAY_APPEND_ELEMENT_STATUS_OK) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error appending map to results.");
                ret = -1;
        }

end:
        if (url) {
                g_string_free(url, true);
        }
        BT_VALUE_PUT_REF_AND_RESET(map);
        return ret;
}

/*
 * Data structure returned:
 *
 * {
 *   <array> = {
 *     [n] = {
 *       <map> = {
 *         {
 *           key = "url",
 *           value = <string>,
 *         },
 *         {
 *           key = "target-hostname",
 *           value = <string>,
 *         },
 *         {
 *           key = "session-name",
 *           value = <string>,
 *         },
 *         {
 *           key = "timer-us",
 *           value = <integer>,
 *         },
 *         {
 *           key = "stream-count",
 *           value = <integer>,
 *         },
 *         {
 *           key = "client-count",
 *           value = <integer>,
 *         },
 *       },
 *     }
 *   }
 */

BT_HIDDEN
bt_component_class_query_method_status live_viewer_connection_list_sessions(
                struct live_viewer_connection *viewer_connection,
                const bt_value **user_result)
{
        bt_self_component_class *self_comp_class = viewer_connection->self_comp_class;
        bt_component_class_query_method_status status =
                BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_OK;
        bt_value *result = NULL;
        enum lttng_live_viewer_status viewer_status;
        struct lttng_viewer_cmd cmd;
        struct lttng_viewer_list_sessions list;
        uint32_t i, sessions_count;

        result = bt_value_array_create();
        if (!result) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error creating array");
                status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_MEMORY_ERROR;
                goto error;
        }

        cmd.cmd = htobe32(LTTNG_VIEWER_LIST_SESSIONS);
        cmd.data_size = htobe64((uint64_t) 0);
        cmd.cmd_version = htobe32(0);

        viewer_status = lttng_live_send(viewer_connection, &cmd, sizeof(cmd));
        if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error sending list sessions command");
                status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
                goto error;
        } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
                status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_AGAIN;
                goto error;
        }

        viewer_status = lttng_live_recv(viewer_connection, &list, sizeof(list));
        if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
                BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                        "Error receiving session list");
                status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
                goto error;
        } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
                status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_AGAIN;
                goto error;
        }

        sessions_count = be32toh(list.sessions_count);
        for (i = 0; i < sessions_count; i++) {
                struct lttng_viewer_session lsession;

                viewer_status = lttng_live_recv(viewer_connection, &lsession,
                        sizeof(lsession));
                if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
                        BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                                "Error receiving session:");
                        status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
                        goto error;
                } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
                        status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_AGAIN;
                        goto error;
                }

                lsession.hostname[LTTNG_VIEWER_HOST_NAME_MAX - 1] = '\0';
                lsession.session_name[LTTNG_VIEWER_NAME_MAX - 1] = '\0';
                if (list_append_session(result, viewer_connection->url,
                                &lsession, viewer_connection)) {
                        BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
                                "Error appending session");
                        status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
                        goto error;
                }
        }

        *user_result = result;
        goto end;
error:
        BT_VALUE_PUT_REF_AND_RESET(result);
end:
        return status;
}

static
enum lttng_live_viewer_status lttng_live_query_session_ids(
                struct lttng_live_msg_iter *lttng_live_msg_iter)
{
        struct lttng_viewer_cmd cmd;
        struct lttng_viewer_list_sessions list;
        struct lttng_viewer_session lsession;
        uint32_t i, sessions_count;
        uint64_t session_id;
        enum lttng_live_viewer_status status;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        bt_self_component *self_comp = viewer_connection->self_comp;
        bt_self_component_class *self_comp_class =
                viewer_connection->self_comp_class;

        BT_COMP_LOGD("Asking the Relay for the list of sessions");

        cmd.cmd = htobe32(LTTNG_VIEWER_LIST_SESSIONS);
        cmd.data_size = htobe64((uint64_t) 0);
        cmd.cmd_version = htobe32(0);

        status = lttng_live_send(viewer_connection, &cmd, sizeof(cmd));
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, self_comp_class,
                        status, "list sessions command");
                goto end;
        }

        status = lttng_live_recv(viewer_connection, &list, sizeof(list));
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, self_comp_class,
                        status, "session list reply");
                goto end;
        }

        sessions_count = be32toh(list.sessions_count);
        for (i = 0; i < sessions_count; i++) {
                status = lttng_live_recv(viewer_connection, &lsession,
                        sizeof(lsession));
                if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                        viewer_handle_recv_status(self_comp, self_comp_class,
                                status, "session reply");
                        goto end;
                }
                lsession.hostname[LTTNG_VIEWER_HOST_NAME_MAX - 1] = '\0';
                lsession.session_name[LTTNG_VIEWER_NAME_MAX - 1] = '\0';
                session_id = be64toh(lsession.id);

                BT_COMP_LOGI("Adding session to internal list: "
                        "session-id=%" PRIu64 ", hostname=\"%s\", session-name=\"%s\"",
                        session_id, lsession.hostname, lsession.session_name);

                if ((strncmp(lsession.session_name,
                        viewer_connection->session_name->str,
                        LTTNG_VIEWER_NAME_MAX) == 0) && (strncmp(lsession.hostname,
                                viewer_connection->target_hostname->str,
                                LTTNG_VIEWER_HOST_NAME_MAX) == 0)) {

                        if (lttng_live_add_session(lttng_live_msg_iter, session_id,
                                        lsession.hostname,
                                        lsession.session_name)) {
                                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                                        "Failed to add live session");
                                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                                goto end;
                        }
                }
        }

        status = LTTNG_LIVE_VIEWER_STATUS_OK;

end:
        return status;
}

BT_HIDDEN
enum lttng_live_viewer_status lttng_live_create_viewer_session(
                struct lttng_live_msg_iter *lttng_live_msg_iter)
{
        struct lttng_viewer_cmd cmd;
        struct lttng_viewer_create_session_response resp;
        enum lttng_live_viewer_status status;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        bt_self_component *self_comp = viewer_connection->self_comp;
        bt_self_component_class *self_comp_class =
                viewer_connection->self_comp_class;

        BT_COMP_OR_COMP_CLASS_LOGD(self_comp, self_comp_class,
                "Creating a viewer session");

        cmd.cmd = htobe32(LTTNG_VIEWER_CREATE_SESSION);
        cmd.data_size = htobe64((uint64_t) 0);
        cmd.cmd_version = htobe32(0);

        status = lttng_live_send(viewer_connection, &cmd, sizeof(cmd));
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, self_comp_class,
                        status, "create session command");
                goto end;
        }

        status = lttng_live_recv(viewer_connection, &resp, sizeof(resp));
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, self_comp_class,
                        status, "create session reply");
                goto end;
        }

        if (be32toh(resp.status) != LTTNG_VIEWER_CREATE_SESSION_OK) {
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Error creating viewer session");
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        }

        status = lttng_live_query_session_ids(lttng_live_msg_iter);
        if (status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Failed to query live viewer session ids");
                goto end;
        } else if (status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
                goto end;
        }

end:
        return status;
}

static
enum lttng_live_viewer_status receive_streams(struct lttng_live_session *session,
                uint32_t stream_count,
                bt_self_message_iterator *self_msg_iter)
{
        uint32_t i;
        struct lttng_live_msg_iter *lttng_live_msg_iter =
                session->lttng_live_msg_iter;
        enum lttng_live_viewer_status status;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        bt_self_component *self_comp = viewer_connection->self_comp;

        BT_COMP_LOGI("Getting %" PRIu32 " new streams:", stream_count);
        for (i = 0; i < stream_count; i++) {
                struct lttng_viewer_stream stream;
                struct lttng_live_stream_iterator *live_stream;
                uint64_t stream_id;
                uint64_t ctf_trace_id;

                status = lttng_live_recv(viewer_connection, &stream,
                        sizeof(stream));
                if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                        viewer_handle_recv_status(self_comp, NULL,
                                status, "stream reply");
                        goto end;
                }
                stream.path_name[LTTNG_VIEWER_PATH_MAX - 1] = '\0';
                stream.channel_name[LTTNG_VIEWER_NAME_MAX - 1] = '\0';
                stream_id = be64toh(stream.id);
                ctf_trace_id = be64toh(stream.ctf_trace_id);

                if (stream.metadata_flag) {
                        BT_COMP_LOGI("    metadata stream %" PRIu64 " : %s/%s",
                                stream_id, stream.path_name, stream.channel_name);
                        if (lttng_live_metadata_create_stream(session,
                                        ctf_trace_id, stream_id,
                                        stream.path_name)) {
                                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                                        "Error creating metadata stream");
                                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                                goto end;
                        }
                        session->lazy_stream_msg_init = true;
                } else {
                        BT_COMP_LOGI("    stream %" PRIu64 " : %s/%s",
                                stream_id, stream.path_name, stream.channel_name);
                        live_stream = lttng_live_stream_iterator_create(session,
                                ctf_trace_id, stream_id, self_msg_iter);
                        if (!live_stream) {
                                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                                        "Error creating stream");
                                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                                goto end;
                        }
                }
        }
        status = LTTNG_LIVE_VIEWER_STATUS_OK;

end:
        return status;
}

BT_HIDDEN
enum lttng_live_viewer_status lttng_live_attach_session(
                struct lttng_live_session *session,
                bt_self_message_iterator *self_msg_iter)
{
        struct lttng_viewer_cmd cmd;
        enum lttng_live_viewer_status status;
        struct lttng_viewer_attach_session_request rq;
        struct lttng_viewer_attach_session_response rp;
        struct lttng_live_msg_iter *lttng_live_msg_iter =
                session->lttng_live_msg_iter;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        bt_self_component *self_comp = viewer_connection->self_comp;
        uint64_t session_id = session->id;
        uint32_t streams_count;
        const size_t cmd_buf_len = sizeof(cmd) + sizeof(rq);
        char cmd_buf[cmd_buf_len];

        BT_COMP_LOGD("Attaching to session: session-id=%"PRIu64, session_id);

        cmd.cmd = htobe32(LTTNG_VIEWER_ATTACH_SESSION);
        cmd.data_size = htobe64((uint64_t) sizeof(rq));
        cmd.cmd_version = htobe32(0);

        memset(&rq, 0, sizeof(rq));
        rq.session_id = htobe64(session_id);
        // TODO: add cmd line parameter to select seek beginning
        // rq.seek = htobe32(LTTNG_VIEWER_SEEK_BEGINNING);
        rq.seek = htobe32(LTTNG_VIEWER_SEEK_LAST);

        /*
         * Merge the cmd and connection request to prevent a write-write
         * sequence on the TCP socket. Otherwise, a delayed ACK will prevent the
         * second write to be performed quickly in presence of Nagle's algorithm.
         */
        memcpy(cmd_buf, &cmd, sizeof(cmd));
        memcpy(cmd_buf + sizeof(cmd), &rq, sizeof(rq));
        status = lttng_live_send(viewer_connection, &cmd_buf, cmd_buf_len);
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, NULL,
                        status, "attach session command");
                goto end;
        }

        status = lttng_live_recv(viewer_connection, &rp, sizeof(rp));
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        status, "attach session reply");
                goto end;
        }

        streams_count = be32toh(rp.streams_count);
        switch(be32toh(rp.status)) {
        case LTTNG_VIEWER_ATTACH_OK:
                break;
        case LTTNG_VIEWER_ATTACH_UNK:
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Session id %" PRIu64 " is unknown", session_id);
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        case LTTNG_VIEWER_ATTACH_ALREADY:
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "There is already a viewer attached to this session");
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        case LTTNG_VIEWER_ATTACH_NOT_LIVE:
                BT_COMP_LOGE_APPEND_CAUSE(self_comp, "Not a live session");
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        case LTTNG_VIEWER_ATTACH_SEEK_ERR:
                BT_COMP_LOGE_APPEND_CAUSE(self_comp, "Wrong seek parameter");
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        default:
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Unknown attach return code %u", be32toh(rp.status));
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        }

        /* We receive the initial list of streams. */
        status = receive_streams(session, streams_count, self_msg_iter);
        switch (status) {
        case LTTNG_LIVE_VIEWER_STATUS_OK:
                break;
        case LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED:
                goto end;
        case LTTNG_LIVE_VIEWER_STATUS_ERROR:
                BT_COMP_LOGE_APPEND_CAUSE(self_comp, "Error receiving streams");
                goto end;
        default:
                bt_common_abort();
        }

        session->attached = true;
        session->new_streams_needed = false;

end:
        return status;
}

BT_HIDDEN
enum lttng_live_viewer_status lttng_live_detach_session(
                struct lttng_live_session *session)
{
        struct lttng_viewer_cmd cmd;
        enum lttng_live_viewer_status status;
        struct lttng_viewer_detach_session_request rq;
        struct lttng_viewer_detach_session_response rp;
        struct lttng_live_msg_iter *lttng_live_msg_iter =
                session->lttng_live_msg_iter;
        bt_self_component *self_comp = session->self_comp;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        uint64_t session_id = session->id;
        const size_t cmd_buf_len = sizeof(cmd) + sizeof(rq);
        char cmd_buf[cmd_buf_len];

        /*
         * The session might already be detached and the viewer socket might
         * already been closed. This happens when calling this function when
         * tearing down the graph after an error.
         */
        if (!session->attached || viewer_connection->control_sock == BT_INVALID_SOCKET) {
                return 0;
        }

        cmd.cmd = htobe32(LTTNG_VIEWER_DETACH_SESSION);
        cmd.data_size = htobe64((uint64_t) sizeof(rq));
        cmd.cmd_version = htobe32(0);

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

        /*
         * Merge the cmd and connection request to prevent a write-write
         * sequence on the TCP socket. Otherwise, a delayed ACK will prevent the
         * second write to be performed quickly in presence of Nagle's algorithm.
         */
        memcpy(cmd_buf, &cmd, sizeof(cmd));
        memcpy(cmd_buf + sizeof(cmd), &rq, sizeof(rq));
        status = lttng_live_send(viewer_connection, &cmd_buf, cmd_buf_len);
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, NULL,
                        status, "detach session command");
                goto end;
        }

        status = lttng_live_recv(viewer_connection, &rp, sizeof(rp));
        if (status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        status, "detach session reply");
                goto end;
        }

        switch(be32toh(rp.status)) {
        case LTTNG_VIEWER_DETACH_SESSION_OK:
                break;
        case LTTNG_VIEWER_DETACH_SESSION_UNK:
                BT_COMP_LOGW("Session id %" PRIu64 " is unknown", session_id);
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        case LTTNG_VIEWER_DETACH_SESSION_ERR:
                BT_COMP_LOGW("Error detaching session id %" PRIu64 "", session_id);
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        default:
                BT_COMP_LOGE("Unknown detach return code %u", be32toh(rp.status));
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto end;
        }

        session->attached = false;

        status = LTTNG_LIVE_VIEWER_STATUS_OK;

end:
        return status;
}

BT_HIDDEN
enum lttng_live_get_one_metadata_status lttng_live_get_one_metadata_packet(
                struct lttng_live_trace *trace, FILE *fp, size_t *reply_len)
{
        uint64_t len = 0;
        enum lttng_live_get_one_metadata_status status;
        enum lttng_live_viewer_status viewer_status;
        struct lttng_viewer_cmd cmd;
        struct lttng_viewer_get_metadata rq;
        struct lttng_viewer_metadata_packet rp;
        char *data = NULL;
        ssize_t writelen;
        struct lttng_live_session *session = trace->session;
        struct lttng_live_msg_iter *lttng_live_msg_iter =
                session->lttng_live_msg_iter;
        struct lttng_live_metadata *metadata = trace->metadata;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        bt_self_component *self_comp = viewer_connection->self_comp;
        const size_t cmd_buf_len = sizeof(cmd) + sizeof(rq);
        char cmd_buf[cmd_buf_len];

        BT_COMP_LOGD("Requesting new metadata for trace: "
                "trace-id=%"PRIu64", metadata-stream-id=%"PRIu64,
                trace->id, metadata->stream_id);

        rq.stream_id = htobe64(metadata->stream_id);
        cmd.cmd = htobe32(LTTNG_VIEWER_GET_METADATA);
        cmd.data_size = htobe64((uint64_t) sizeof(rq));
        cmd.cmd_version = htobe32(0);

        /*
         * Merge the cmd and connection request to prevent a write-write
         * sequence on the TCP socket. Otherwise, a delayed ACK will prevent the
         * second write to be performed quickly in presence of Nagle's algorithm.
         */
        memcpy(cmd_buf, &cmd, sizeof(cmd));
        memcpy(cmd_buf + sizeof(cmd), &rq, sizeof(rq));
        viewer_status = lttng_live_send(viewer_connection, &cmd_buf, cmd_buf_len);
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, NULL,
                        viewer_status, "get metadata command");
                status = (enum lttng_live_get_one_metadata_status) viewer_status;
                goto end;
        }

        viewer_status = lttng_live_recv(viewer_connection, &rp, sizeof(rp));
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        viewer_status, "get metadata reply");
                status = (enum lttng_live_get_one_metadata_status) viewer_status;
                goto end;
        }

        switch (be32toh(rp.status)) {
                case LTTNG_VIEWER_METADATA_OK:
                        BT_COMP_LOGD("Received get_metadata response: ok");
                        break;
                case LTTNG_VIEWER_NO_NEW_METADATA:
                        BT_COMP_LOGD("Received get_metadata response: no new");
                        status = LTTNG_LIVE_GET_ONE_METADATA_STATUS_END;
                        goto end;
                case LTTNG_VIEWER_METADATA_ERR:
                        /*
                         * The Relayd cannot find this stream id. Maybe its
                         * gone already. This can happen in short lived UST app
                         * in a per-pid session.
                         */
                        BT_COMP_LOGD("Received get_metadata response: error");
                        status = LTTNG_LIVE_GET_ONE_METADATA_STATUS_CLOSED;
                        goto end;
                default:
                        BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                                "Received get_metadata response: unknown");
                        status = LTTNG_LIVE_GET_ONE_METADATA_STATUS_ERROR;
                        goto error;
        }

        len = be64toh(rp.len);
        BT_COMP_LOGD("Writing %" PRIu64" bytes to metadata", len);
        if (len <= 0) {
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Erroneous response length");
                status = LTTNG_LIVE_GET_ONE_METADATA_STATUS_ERROR;
                goto error;
        }

        data = calloc(1, len);
        if (!data) {
                BT_COMP_LOGE_APPEND_CAUSE_ERRNO(self_comp,
                        "Failed to allocate data buffer", ".");
                status = LTTNG_LIVE_GET_ONE_METADATA_STATUS_ERROR;
                goto error;
        }

        viewer_status = lttng_live_recv(viewer_connection, data, len);
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        viewer_status, "get metadata packet");
                status = (enum lttng_live_get_one_metadata_status) viewer_status;
                goto error;
        }

        /*
         * Write the metadata to the file handle.
         */
        writelen = fwrite(data, sizeof(uint8_t), len, fp);
        if (writelen != len) {
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Writing in the metadata file stream");
                status = LTTNG_LIVE_GET_ONE_METADATA_STATUS_ERROR;
                goto error;
        }

        *reply_len = len;
        status = LTTNG_LIVE_GET_ONE_METADATA_STATUS_OK;

error:
        free(data);

end:
        return status;
}

/*
 * Assign the fields from a lttng_viewer_index to a packet_index.
 */
static
void lttng_index_to_packet_index(struct lttng_viewer_index *lindex,
                struct packet_index *pindex)
{
        BT_ASSERT(lindex);
        BT_ASSERT(pindex);

        pindex->offset = be64toh(lindex->offset);
        pindex->packet_size = be64toh(lindex->packet_size);
        pindex->content_size = be64toh(lindex->content_size);
        pindex->ts_cycles.timestamp_begin = be64toh(lindex->timestamp_begin);
        pindex->ts_cycles.timestamp_end = be64toh(lindex->timestamp_end);
        pindex->events_discarded = be64toh(lindex->events_discarded);
}

BT_HIDDEN
enum lttng_live_iterator_status lttng_live_get_next_index(
                struct lttng_live_msg_iter *lttng_live_msg_iter,
                struct lttng_live_stream_iterator *stream,
                struct packet_index *index)
{
        struct lttng_viewer_cmd cmd;
        struct lttng_viewer_get_next_index rq;
        enum lttng_live_viewer_status viewer_status;
        struct lttng_viewer_index rp;
        enum lttng_live_iterator_status status;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        bt_self_component *self_comp = viewer_connection->self_comp;
        struct lttng_live_trace *trace = stream->trace;
        const size_t cmd_buf_len = sizeof(cmd) + sizeof(rq);
        char cmd_buf[cmd_buf_len];
        uint32_t flags, rp_status;

        BT_COMP_LOGD("Requesting next index for stream: "
                "stream-id=%"PRIu64, stream->viewer_stream_id);

        cmd.cmd = htobe32(LTTNG_VIEWER_GET_NEXT_INDEX);
        cmd.data_size = htobe64((uint64_t) sizeof(rq));
        cmd.cmd_version = htobe32(0);


        memset(&rq, 0, sizeof(rq));
        rq.stream_id = htobe64(stream->viewer_stream_id);

        /*
         * Merge the cmd and connection request to prevent a write-write
         * sequence on the TCP socket. Otherwise, a delayed ACK will prevent the
         * second write to be performed quickly in presence of Nagle's algorithm.
         */
        memcpy(cmd_buf, &cmd, sizeof(cmd));
        memcpy(cmd_buf + sizeof(cmd), &rq, sizeof(rq));
        viewer_status = lttng_live_send(viewer_connection, &cmd_buf, cmd_buf_len);
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, NULL,
                        viewer_status, "get next index command");
                goto error;
        }

        viewer_status = lttng_live_recv(viewer_connection, &rp, sizeof(rp));
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        viewer_status, "get next index reply");
                goto error;
        }

        flags = be32toh(rp.flags);
        rp_status = be32toh(rp.status);

        switch (rp_status) {
        case LTTNG_VIEWER_INDEX_INACTIVE:
        {
                uint64_t ctf_stream_class_id;

                BT_COMP_LOGD("Received get_next_index response: inactive");
                memset(index, 0, sizeof(struct packet_index));
                index->ts_cycles.timestamp_end = be64toh(rp.timestamp_end);
                stream->current_inactivity_ts = index->ts_cycles.timestamp_end;
                ctf_stream_class_id = be64toh(rp.stream_id);
                if (stream->ctf_stream_class_id != -1ULL) {
                        BT_ASSERT(stream->ctf_stream_class_id ==
                                ctf_stream_class_id);
                } else {
                        stream->ctf_stream_class_id = ctf_stream_class_id;
                }
                stream->state = LTTNG_LIVE_STREAM_QUIESCENT;
                status = LTTNG_LIVE_ITERATOR_STATUS_OK;
                break;
        }
        case LTTNG_VIEWER_INDEX_OK:
        {
                uint64_t ctf_stream_class_id;

                BT_COMP_LOGD("Received get_next_index response: OK");
                lttng_index_to_packet_index(&rp, index);
                ctf_stream_class_id = be64toh(rp.stream_id);
                if (stream->ctf_stream_class_id != -1ULL) {
                        BT_ASSERT(stream->ctf_stream_class_id ==
                                ctf_stream_class_id);
                } else {
                        stream->ctf_stream_class_id = ctf_stream_class_id;
                }

                stream->state = LTTNG_LIVE_STREAM_ACTIVE_DATA;

                if (flags & LTTNG_VIEWER_FLAG_NEW_METADATA) {
                        BT_COMP_LOGD("Received get_next_index response: new metadata needed");
                        trace->metadata_stream_state = LTTNG_LIVE_METADATA_STREAM_STATE_NEEDED;
                }
                if (flags & LTTNG_VIEWER_FLAG_NEW_STREAM) {
                        BT_COMP_LOGD("Received get_next_index response: new streams needed");
                        lttng_live_need_new_streams(lttng_live_msg_iter);
                }
                status = LTTNG_LIVE_ITERATOR_STATUS_OK;
                break;
        }
        case LTTNG_VIEWER_INDEX_RETRY:
                BT_COMP_LOGD("Received get_next_index response: retry");
                memset(index, 0, sizeof(struct packet_index));
                stream->state = LTTNG_LIVE_STREAM_ACTIVE_NO_DATA;
                status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
                goto end;
        case LTTNG_VIEWER_INDEX_HUP:
                BT_COMP_LOGD("Received get_next_index response: stream hung up");
                memset(index, 0, sizeof(struct packet_index));
                index->offset = EOF;
                stream->state = LTTNG_LIVE_STREAM_EOF;
                stream->has_stream_hung_up = true;
                status = LTTNG_LIVE_ITERATOR_STATUS_END;
                break;
        case LTTNG_VIEWER_INDEX_ERR:
                BT_COMP_LOGD("Received get_next_index response: error");
                memset(index, 0, sizeof(struct packet_index));
                stream->state = LTTNG_LIVE_STREAM_ACTIVE_NO_DATA;
                status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
                goto end;
        default:
                BT_COMP_LOGD("Received get_next_index response: unknown value");
                memset(index, 0, sizeof(struct packet_index));
                stream->state = LTTNG_LIVE_STREAM_ACTIVE_NO_DATA;
                status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
                goto end;
        }
        goto end;

error:
        status = viewer_status_to_live_iterator_status(viewer_status);
end:
        return status;
}

BT_HIDDEN
enum ctf_msg_iter_medium_status lttng_live_get_stream_bytes(
                struct lttng_live_msg_iter *lttng_live_msg_iter,
                struct lttng_live_stream_iterator *stream, uint8_t *buf,
                uint64_t offset, uint64_t req_len, uint64_t *recv_len)
{
        enum ctf_msg_iter_medium_status status;
        enum lttng_live_viewer_status viewer_status;
        struct lttng_viewer_trace_packet rp;
        struct lttng_viewer_cmd cmd;
        struct lttng_viewer_get_packet rq;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        bt_self_component *self_comp = viewer_connection->self_comp;
        struct lttng_live_trace *trace = stream->trace;
        const size_t cmd_buf_len = sizeof(cmd) + sizeof(rq);
        char cmd_buf[cmd_buf_len];
        uint32_t flags, rp_status;

        BT_COMP_LOGD("lttng_live_get_stream_bytes: offset=%" PRIu64 ", req_len=%" PRIu64,
                        offset, req_len);
        cmd.cmd = htobe32(LTTNG_VIEWER_GET_PACKET);
        cmd.data_size = htobe64((uint64_t) sizeof(rq));
        cmd.cmd_version = htobe32(0);

        memset(&rq, 0, sizeof(rq));
        rq.stream_id = htobe64(stream->viewer_stream_id);
        rq.offset = htobe64(offset);
        rq.len = htobe32(req_len);

        /*
         * Merge the cmd and connection request to prevent a write-write
         * sequence on the TCP socket. Otherwise, a delayed ACK will prevent the
         * second write to be performed quickly in presence of Nagle's algorithm.
         */
        memcpy(cmd_buf, &cmd, sizeof(cmd));
        memcpy(cmd_buf + sizeof(cmd), &rq, sizeof(rq));
        viewer_status = lttng_live_send(viewer_connection, &cmd_buf, cmd_buf_len);
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, NULL,
                        viewer_status, "get data packet command");
                goto error;
        }

        viewer_status = lttng_live_recv(viewer_connection, &rp, sizeof(rp));
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        viewer_status, "get data packet reply");
                goto error;
        }

        flags = be32toh(rp.flags);
        rp_status = be32toh(rp.status);

        switch (rp_status) {
        case LTTNG_VIEWER_GET_PACKET_OK:
                req_len = be32toh(rp.len);
                BT_COMP_LOGD("Received get_data_packet response: Ok, "
                        "packet size : %" PRIu64 "", req_len);
                status = CTF_MSG_ITER_MEDIUM_STATUS_OK;
                break;
        case LTTNG_VIEWER_GET_PACKET_RETRY:
                /* Unimplemented by relay daemon */
                BT_COMP_LOGD("Received get_data_packet response: retry");
                status = CTF_MSG_ITER_MEDIUM_STATUS_AGAIN;
                goto end;
        case LTTNG_VIEWER_GET_PACKET_ERR:
                if (flags & LTTNG_VIEWER_FLAG_NEW_METADATA) {
                        BT_COMP_LOGD("get_data_packet: new metadata needed, try again later");
                        trace->metadata_stream_state = LTTNG_LIVE_METADATA_STREAM_STATE_NEEDED;
                }
                if (flags & LTTNG_VIEWER_FLAG_NEW_STREAM) {
                        BT_COMP_LOGD("get_data_packet: new streams needed, try again later");
                        lttng_live_need_new_streams(lttng_live_msg_iter);
                }
                if (flags & (LTTNG_VIEWER_FLAG_NEW_METADATA
                                | LTTNG_VIEWER_FLAG_NEW_STREAM)) {
                        status = CTF_MSG_ITER_MEDIUM_STATUS_AGAIN;
                        goto end;
                }
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Received get_data_packet response: error");
                status = CTF_MSG_ITER_MEDIUM_STATUS_ERROR;
                goto end;
        case LTTNG_VIEWER_GET_PACKET_EOF:
                status = CTF_MSG_ITER_MEDIUM_STATUS_EOF;
                goto end;
        default:
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Received get_data_packet response: unknown");
                status = CTF_MSG_ITER_MEDIUM_STATUS_ERROR;
                goto error;
        }

        if (req_len == 0) {
                status = CTF_MSG_ITER_MEDIUM_STATUS_ERROR;
                goto error;
        }

        viewer_status = lttng_live_recv(viewer_connection, buf, req_len);
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        viewer_status, "get data packet");
                goto error;
        }
        *recv_len = req_len;

        status = CTF_MSG_ITER_MEDIUM_STATUS_OK;
        goto end;
error:

        status = viewer_status_to_ctf_msg_iter_medium_status(viewer_status);
end:
        return status;
}

/*
 * Request new streams for a session.
 */
BT_HIDDEN
enum lttng_live_iterator_status lttng_live_get_new_streams(
                struct lttng_live_session *session,
                bt_self_message_iterator *self_msg_iter)
{
        enum lttng_live_iterator_status status =
                LTTNG_LIVE_ITERATOR_STATUS_OK;
        struct lttng_viewer_cmd cmd;
        struct lttng_viewer_new_streams_request rq;
        struct lttng_viewer_new_streams_response rp;
        struct lttng_live_msg_iter *lttng_live_msg_iter =
                session->lttng_live_msg_iter;
        enum lttng_live_viewer_status viewer_status;
        struct live_viewer_connection *viewer_connection =
                lttng_live_msg_iter->viewer_connection;
        bt_self_component *self_comp = viewer_connection->self_comp;
        uint32_t streams_count;
        const size_t cmd_buf_len = sizeof(cmd) + sizeof(rq);
        char cmd_buf[cmd_buf_len];

        if (!session->new_streams_needed) {
                status = LTTNG_LIVE_ITERATOR_STATUS_OK;
                goto end;
        }

        BT_COMP_LOGD("Requesting new streams for session: "
                "session-id=%"PRIu64, session->id);

        cmd.cmd = htobe32(LTTNG_VIEWER_GET_NEW_STREAMS);
        cmd.data_size = htobe64((uint64_t) sizeof(rq));
        cmd.cmd_version = htobe32(0);

        memset(&rq, 0, sizeof(rq));
        rq.session_id = htobe64(session->id);

        /*
         * Merge the cmd and connection request to prevent a write-write
         * sequence on the TCP socket. Otherwise, a delayed ACK will prevent the
         * second write to be performed quickly in presence of Nagle's algorithm.
         */
        memcpy(cmd_buf, &cmd, sizeof(cmd));
        memcpy(cmd_buf + sizeof(cmd), &rq, sizeof(rq));
        viewer_status = lttng_live_send(viewer_connection, &cmd_buf, cmd_buf_len);
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_send_status(self_comp, NULL,
                        viewer_status, "get new streams command");
                status = viewer_status_to_live_iterator_status(viewer_status);
                goto end;
        }

        viewer_status = lttng_live_recv(viewer_connection, &rp, sizeof(rp));
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        viewer_status, "get new streams reply");
                status = viewer_status_to_live_iterator_status(viewer_status);
                goto end;
        }

        streams_count = be32toh(rp.streams_count);

        switch(be32toh(rp.status)) {
        case LTTNG_VIEWER_NEW_STREAMS_OK:
                session->new_streams_needed = false;
                break;
        case LTTNG_VIEWER_NEW_STREAMS_NO_NEW:
                session->new_streams_needed = false;
                goto end;
        case LTTNG_VIEWER_NEW_STREAMS_HUP:
                session->new_streams_needed = false;
                session->closed = true;
                status = LTTNG_LIVE_ITERATOR_STATUS_END;
                goto end;
        case LTTNG_VIEWER_NEW_STREAMS_ERR:
                BT_COMP_LOGD("Received get_new_streams response: error");
                status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
                goto end;
        default:
                BT_COMP_LOGE_APPEND_CAUSE(self_comp,
                        "Received get_new_streams response: Unknown:"
                        "return code %u", be32toh(rp.status));
                status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
                goto end;
        }

        viewer_status = receive_streams(session, streams_count, self_msg_iter);
        if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
                viewer_handle_recv_status(self_comp, NULL,
                        viewer_status, "new streams");
                status = viewer_status_to_live_iterator_status(viewer_status);
                goto end;
        }

        status = LTTNG_LIVE_ITERATOR_STATUS_OK;
end:
        return status;
}

BT_HIDDEN
enum lttng_live_viewer_status live_viewer_connection_create(
                bt_self_component *self_comp,
                bt_self_component_class *self_comp_class,
                bt_logging_level log_level,
                const char *url, bool in_query,
                struct lttng_live_msg_iter *lttng_live_msg_iter,
                struct live_viewer_connection **viewer)
{
        struct live_viewer_connection *viewer_connection;
        enum lttng_live_viewer_status status;

        viewer_connection = g_new0(struct live_viewer_connection, 1);

        if (bt_socket_init(log_level) != 0) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Failed to init socket");
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto error;
        }

        viewer_connection->log_level = log_level;

        viewer_connection->self_comp = self_comp;
        viewer_connection->self_comp_class = self_comp_class;

        viewer_connection->control_sock = BT_INVALID_SOCKET;
        viewer_connection->port = -1;
        viewer_connection->in_query = in_query;
        viewer_connection->lttng_live_msg_iter = lttng_live_msg_iter;
        viewer_connection->url = g_string_new(url);
        if (!viewer_connection->url) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Failed to allocate URL buffer");
                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                goto error;
        }

        BT_COMP_OR_COMP_CLASS_LOGD(self_comp, self_comp_class,
                "Establishing connection to url \"%s\"...", url);
        status = lttng_live_connect_viewer(viewer_connection);
        /*
         * Only print error and append cause in case of error. not in case of
         * interruption.
         */
        if (status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
                BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                        self_comp_class, "Failed to establish connection: "
                        "url=\"%s\"", url);
                goto error;
        } else if (status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
                goto error;
        }
        BT_COMP_OR_COMP_CLASS_LOGD(self_comp, self_comp_class,
                "Connection to url \"%s\" is established", url);

        *viewer = viewer_connection;
        status = LTTNG_LIVE_VIEWER_STATUS_OK;
        goto end;

error:
        if (viewer_connection) {
                live_viewer_connection_destroy(viewer_connection);
        }
end:
        return status;
}

BT_HIDDEN
void live_viewer_connection_destroy(
                struct live_viewer_connection *viewer_connection)
{
        bt_self_component *self_comp = viewer_connection->self_comp;
        bt_self_component_class *self_comp_class = viewer_connection->self_comp_class;

        if (!viewer_connection) {
                goto end;
        }

        BT_COMP_OR_COMP_CLASS_LOGD(self_comp, self_comp_class,
                "Closing connection to relay:"
                "relay-url=\"%s\"", viewer_connection->url->str);

        lttng_live_disconnect_viewer(viewer_connection);

        if (viewer_connection->url) {
                g_string_free(viewer_connection->url, true);
        }

        if (viewer_connection->relay_hostname) {
                g_string_free(viewer_connection->relay_hostname, true);
        }

        if (viewer_connection->target_hostname) {
                g_string_free(viewer_connection->target_hostname, true);
        }

        if (viewer_connection->session_name) {
                g_string_free(viewer_connection->session_name, true);
        }

        if (viewer_connection->proto) {
                g_string_free(viewer_connection->proto, true);
        }

        g_free(viewer_connection);

        bt_socket_fini();

end:
        return;
}