static ngx_http_push_stream_padding_t *
ngx_http_push_stream_get_padding_by_user_agent(ngx_http_request_t *r)
{
    ngx_http_push_stream_loc_conf_t                *cf = ngx_http_get_module_loc_conf(r, ngx_http_push_stream_module);
    ngx_http_push_stream_padding_t                 *padding = cf->paddings;
    ngx_str_t                                       vv_user_agent = ngx_null_string;

    if (cf->user_agent != NULL) {
        ngx_http_push_stream_complex_value(r, cf->user_agent, &vv_user_agent);
    } else if (r->headers_in.user_agent != NULL) {
        vv_user_agent = r->headers_in.user_agent->value;
    }

    if ((padding != NULL) && (vv_user_agent.len > 0)) {
        while ((padding = (ngx_http_push_stream_padding_t *) ngx_queue_next(&padding->queue)) != cf->paddings) {
            if (ngx_regex_exec(padding->agent, &vv_user_agent, NULL, 0) >= 0) {
                return padding;
            }
        }
    }

    return NULL;
}
static ngx_http_push_stream_padding_t *
ngx_http_push_stream_get_padding_by_user_agent(ngx_http_request_t *r)
{
    ngx_http_push_stream_loc_conf_t                *cf = ngx_http_get_module_loc_conf(r, ngx_http_push_stream_module);
    ngx_queue_t                                    *q;
    ngx_str_t                                       vv_user_agent = ngx_null_string;

    if (cf->user_agent != NULL) {
        ngx_http_push_stream_complex_value(r, cf->user_agent, &vv_user_agent);
    } else if (r->headers_in.user_agent != NULL) {
        vv_user_agent = r->headers_in.user_agent->value;
    }

    if ((cf->paddings != NULL) && (vv_user_agent.len > 0)) {
        for (q = ngx_queue_head(cf->paddings); q != ngx_queue_sentinel(cf->paddings); q = ngx_queue_next(q)) {
            ngx_http_push_stream_padding_t *padding = ngx_queue_data(q, ngx_http_push_stream_padding_t, queue);
            if (ngx_regex_exec(padding->agent, &vv_user_agent, NULL, 0) >= 0) {
                return padding;
            }
        }
    }

    return NULL;
}
static ngx_int_t
ngx_http_push_stream_subscriber_handler(ngx_http_request_t *r)
{
    ngx_slab_pool_t                                *shpool = (ngx_slab_pool_t *)ngx_http_push_stream_shm_zone->shm.addr;
    ngx_http_push_stream_loc_conf_t                *cf = ngx_http_get_module_loc_conf(r, ngx_http_push_stream_module);
    ngx_http_push_stream_subscriber_t              *worker_subscriber;
    ngx_http_push_stream_requested_channel_t       *channels_ids, *cur;
    ngx_http_push_stream_subscriber_ctx_t          *ctx;
    time_t                                          if_modified_since;
    ngx_str_t                                      *last_event_id, vv_time = ngx_null_string;
    ngx_str_t                                      *push_mode;
    ngx_flag_t                                      polling, longpolling;
    ngx_int_t                                       rc;
    ngx_int_t                                       status_code;
    ngx_str_t                                      *explain_error_message;

    // add headers to support cross domain requests
    if (cf->allowed_origins.len > 0) {
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_ORIGIN, &cf->allowed_origins);
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_METHODS, &NGX_HTTP_PUSH_STREAM_ALLOW_GET);
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_HEADERS, &NGX_HTTP_PUSH_STREAM_ALLOWED_HEADERS);
    }

    if (r->method & NGX_HTTP_OPTIONS) {
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_OK, NULL);
    }

    // only accept GET method
    if (!(r->method & NGX_HTTP_GET)) {
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ALLOW, &NGX_HTTP_PUSH_STREAM_ALLOW_GET);
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_NOT_ALLOWED, NULL);
    }

    if ((ctx = ngx_http_push_stream_add_request_context(r)) == NULL) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: unable to create request context");
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    //get channels ids and backtracks from path
    channels_ids = ngx_http_push_stream_parse_channels_ids_from_path(r, ctx->temp_pool);
    if ((channels_ids == NULL) || ngx_queue_empty(&channels_ids->queue)) {
        ngx_log_error(NGX_LOG_WARN, r->connection->log, 0, "push stream module: the $push_stream_channels_path variable is required but is not set");
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_BAD_REQUEST, &NGX_HTTP_PUSH_STREAM_NO_CHANNEL_ID_MESSAGE);
    }

    //validate channels: name, length and quantity. check if channel exists when authorized_channels_only is on. check if channel is full of subscribers
    if (ngx_http_push_stream_validate_channels(r, channels_ids, &status_code, &explain_error_message) == NGX_ERROR) {
        return ngx_http_push_stream_send_only_header_response(r, status_code, explain_error_message);
    }

    if (cf->last_received_message_time != NULL) {
        ngx_http_push_stream_complex_value(r, cf->last_received_message_time, &vv_time);
    } else if (r->headers_in.if_modified_since != NULL) {
        vv_time = r->headers_in.if_modified_since->value;
    }

    // get control headers
    if_modified_since = vv_time.len ? ngx_http_parse_time(vv_time.data, vv_time.len) : -1;
    last_event_id = ngx_http_push_stream_get_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_LAST_EVENT_ID);

    push_mode = ngx_http_push_stream_get_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_MODE);
    polling = ((cf->location_type == NGX_HTTP_PUSH_STREAM_SUBSCRIBER_MODE_POLLING) || ((push_mode != NULL) && (push_mode->len == NGX_HTTP_PUSH_STREAM_MODE_POLLING.len) && (ngx_strncasecmp(push_mode->data, NGX_HTTP_PUSH_STREAM_MODE_POLLING.data, NGX_HTTP_PUSH_STREAM_MODE_POLLING.len) == 0)));
    longpolling = ((cf->location_type == NGX_HTTP_PUSH_STREAM_SUBSCRIBER_MODE_LONGPOLLING) || ((push_mode != NULL) && (push_mode->len == NGX_HTTP_PUSH_STREAM_MODE_LONGPOLLING.len) && (ngx_strncasecmp(push_mode->data, NGX_HTTP_PUSH_STREAM_MODE_LONGPOLLING.data, NGX_HTTP_PUSH_STREAM_MODE_LONGPOLLING.len) == 0)));

    if (polling || longpolling) {
        ngx_int_t result = ngx_http_push_stream_subscriber_polling_handler(r, channels_ids, if_modified_since, last_event_id, longpolling, ctx->temp_pool);
        if (ctx->temp_pool != NULL) {
            ngx_destroy_pool(ctx->temp_pool);
            ctx->temp_pool = NULL;
        }
        return result;
    }

    ctx->padding = ngx_http_push_stream_get_padding_by_user_agent(r);

    // stream access
    if ((worker_subscriber = ngx_http_push_stream_subscriber_prepare_request_to_keep_connected(r)) == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_TRANSFER_ENCODING, &NGX_HTTP_PUSH_STREAM_HEADER_CHUNCKED);
    ngx_http_send_header(r);

    // sending response content header
    if (ngx_http_push_stream_send_response_content_header(r, cf) == NGX_ERROR) {
        ngx_log_error(NGX_LOG_ERR, (r)->connection->log, 0, "push stream module: could not send content header to subscriber");
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    ngx_shmtx_lock(&shpool->mutex);
    rc = ngx_http_push_stream_registry_subscriber_locked(r, worker_subscriber);
    ngx_shmtx_unlock(&shpool->mutex);

    if (rc == NGX_ERROR) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    // adding subscriber to channel(s) and send backtrack messages
    cur = channels_ids;
    while ((cur = (ngx_http_push_stream_requested_channel_t *) ngx_queue_next(&cur->queue)) != channels_ids) {
        if (ngx_http_push_stream_subscriber_assign_channel(shpool, cf, r, cur, if_modified_since, last_event_id, worker_subscriber, ctx->temp_pool) != NGX_OK) {
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    }

    if (ctx->temp_pool != NULL) {
        ngx_destroy_pool(ctx->temp_pool);
        ctx->temp_pool = NULL;
    }
    return NGX_DONE;
}
static ngx_int_t
ngx_http_push_stream_subscriber_polling_handler(ngx_http_request_t *r, ngx_http_push_stream_requested_channel_t *channels_ids, time_t if_modified_since, ngx_str_t *last_event_id, ngx_flag_t longpolling, ngx_pool_t *temp_pool)
{
    ngx_http_push_stream_loc_conf_t                *cf = ngx_http_get_module_loc_conf(r, ngx_http_push_stream_module);
    ngx_slab_pool_t                                *shpool = (ngx_slab_pool_t *)ngx_http_push_stream_shm_zone->shm.addr;
    ngx_http_push_stream_subscriber_ctx_t          *ctx = ngx_http_get_module_ctx(r, ngx_http_push_stream_module);
    ngx_http_push_stream_requested_channel_t       *cur;
    ngx_http_push_stream_subscriber_t              *worker_subscriber;
    ngx_http_push_stream_channel_t                 *channel;
    ngx_http_push_stream_subscription_t            *subscription;
    ngx_str_t                                      *etag = NULL, vv_etag = ngx_null_string;
    ngx_int_t                                       tag;
    time_t                                          greater_message_time;
    ngx_int_t                                       greater_message_tag;
    ngx_flag_t                                      has_message_to_send = 0;
    ngx_str_t                                       callback_function_name;

    if (cf->last_received_message_tag != NULL) {
        ngx_http_push_stream_complex_value(r, cf->last_received_message_tag, &vv_etag);
        etag = vv_etag.len ? &vv_etag : NULL;
    } else {
        etag = ngx_http_push_stream_get_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_IF_NONE_MATCH);
    }

    if (ngx_http_arg(r, NGX_HTTP_PUSH_STREAM_CALLBACK.data, NGX_HTTP_PUSH_STREAM_CALLBACK.len, &callback_function_name) == NGX_OK) {
        ngx_http_push_stream_unescape_uri(&callback_function_name);
        if ((ctx->callback = ngx_http_push_stream_get_formatted_chunk(callback_function_name.data, callback_function_name.len, r->pool)) == NULL) {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: unable to allocate memory for callback function name");
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    }

    tag = ((etag != NULL) && ((tag = ngx_atoi(etag->data, etag->len)) != NGX_ERROR)) ? ngx_abs(tag) : -1;

    greater_message_tag = tag;
    greater_message_time = if_modified_since = (if_modified_since < 0) ? 0 : if_modified_since;

    ngx_shmtx_lock(&shpool->mutex);

    // check if has any message to send
    cur = channels_ids;
    while ((cur = (ngx_http_push_stream_requested_channel_t *) ngx_queue_next(&cur->queue)) != channels_ids) {
        channel = ngx_http_push_stream_find_channel(cur->id, r->connection->log);
        if (channel == NULL) {
            // channel not found
            ngx_shmtx_unlock(&shpool->mutex);
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: unable to allocate shared memory for channel %s", cur->id->data);
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }

        if (ngx_http_push_stream_has_old_messages_to_send(channel, cur->backtrack_messages, if_modified_since, tag, greater_message_time, greater_message_tag, last_event_id)) {
            has_message_to_send = 1;
            if (channel->last_message_time > greater_message_time) {
                greater_message_time = channel->last_message_time;
                greater_message_tag = channel->last_message_tag;
            } else {
                if ((channel->last_message_time == greater_message_time) && (channel->last_message_tag > greater_message_tag) ) {
                    greater_message_tag = channel->last_message_tag;
                }
            }
        }
    }


    if (longpolling && !has_message_to_send) {
        // long polling mode without messages
        if ((worker_subscriber = ngx_http_push_stream_subscriber_prepare_request_to_keep_connected(r)) == NULL) {
            ngx_shmtx_unlock(&shpool->mutex);
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
        worker_subscriber->longpolling = 1;

        if (ngx_http_push_stream_registry_subscriber_locked(r, worker_subscriber) == NGX_ERROR) {
            ngx_shmtx_unlock(&shpool->mutex);
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }

        // adding subscriber to channel(s)
        cur = channels_ids;
        while ((cur = (ngx_http_push_stream_requested_channel_t *) ngx_queue_next(&cur->queue)) != channels_ids) {
            if ((channel = ngx_http_push_stream_find_channel(cur->id, r->connection->log)) == NULL) {
                // channel not found
                ngx_shmtx_unlock(&shpool->mutex);
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: unable to allocate shared memory for channel %s", cur->id->data);
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            if ((subscription = ngx_http_push_stream_create_channel_subscription(r, channel, worker_subscriber)) == NULL) {
                ngx_shmtx_unlock(&shpool->mutex);
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            ngx_http_push_stream_assing_subscription_to_channel_locked(shpool, cur->id, subscription, &worker_subscriber->subscriptions_sentinel, r->connection->log);
        }

        ngx_shmtx_unlock(&shpool->mutex);
        return NGX_DONE;
    }

    ngx_shmtx_unlock(&shpool->mutex);

    // polling or long polling without messages to send

    ngx_http_push_stream_add_polling_headers(r, greater_message_time, greater_message_tag, temp_pool);

    if (!has_message_to_send) {
        // polling subscriber requests get a 304 with their entity tags preserved if don't have new messages.
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_NOT_MODIFIED, NULL);
    }

    // polling with messages or long polling without messages to send
    r->headers_out.status = NGX_HTTP_OK;
    r->headers_out.content_length_n = -1;

    ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_TRANSFER_ENCODING, &NGX_HTTP_PUSH_STREAM_HEADER_CHUNCKED);
    ngx_http_send_header(r);

    // sending response content header
    if (ngx_http_push_stream_send_response_content_header(r, cf) == NGX_ERROR) {
        ngx_log_error(NGX_LOG_ERR, (r)->connection->log, 0, "push stream module: could not send content header to subscriber");
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    if (ctx->callback != NULL) {
        ngx_http_push_stream_send_response_text(r, ctx->callback->data, ctx->callback->len, 0);
        ngx_http_push_stream_send_response_text(r, NGX_HTTP_PUSH_STREAM_CALLBACK_INIT_CHUNK.data, NGX_HTTP_PUSH_STREAM_CALLBACK_INIT_CHUNK.len, 0);
    }

    cur = channels_ids;
    while ((cur = (ngx_http_push_stream_requested_channel_t *) ngx_queue_next(&cur->queue)) != channels_ids) {
        channel = ngx_http_push_stream_find_channel(cur->id, r->connection->log);
        if (channel == NULL) {
            // channel not found
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: unable to allocate shared memory for channel %s", cur->id->data);
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
        ngx_http_push_stream_send_old_messages(r, channel, cur->backtrack_messages, if_modified_since, tag, greater_message_time, greater_message_tag, last_event_id);
    }

    if (ctx->callback != NULL) {
        ngx_http_push_stream_send_response_text(r, NGX_HTTP_PUSH_STREAM_CALLBACK_END_CHUNK.data, NGX_HTTP_PUSH_STREAM_CALLBACK_END_CHUNK.len, 0);
    }

    if (cf->footer_template.len > 0) {
        ngx_http_push_stream_send_response_text(r, cf->footer_template.data, cf->footer_template.len, 0);
    }

    ngx_http_push_stream_send_response_text(r, NGX_HTTP_PUSH_STREAM_LAST_CHUNK.data, NGX_HTTP_PUSH_STREAM_LAST_CHUNK.len, 1);

    return NGX_OK;
}
static ngx_int_t
ngx_http_push_stream_publisher_handler(ngx_http_request_t *r)
{
    ngx_http_push_stream_main_conf_t   *mcf = ngx_http_get_module_main_conf(r, ngx_http_push_stream_module);
    ngx_http_push_stream_loc_conf_t    *cf = ngx_http_get_module_loc_conf(r, ngx_http_push_stream_module);
    ngx_http_push_stream_module_ctx_t  *ctx;

    ngx_http_push_stream_requested_channel_t       *requested_channels, *requested_channel;
    ngx_str_t                                       vv_allowed_origins = ngx_null_string;
    ngx_queue_t                                     *q;

    ngx_http_push_stream_set_expires(r, NGX_HTTP_PUSH_STREAM_EXPIRES_EPOCH, 0);


    if (cf->allowed_origins != NULL) {
        ngx_http_push_stream_complex_value(r, cf->allowed_origins, &vv_allowed_origins);
    }

    if (vv_allowed_origins.len > 0) {
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_ORIGIN, &vv_allowed_origins);
        const ngx_str_t *header_value = (cf->location_type == NGX_HTTP_PUSH_STREAM_PUBLISHER_MODE_ADMIN) ? &NGX_HTTP_PUSH_STREAM_ALLOW_GET_POST_PUT_DELETE_METHODS : &NGX_HTTP_PUSH_STREAM_ALLOW_GET_POST_PUT_METHODS;
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_METHODS, header_value);
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_HEADERS, &NGX_HTTP_PUSH_STREAM_ALLOWED_HEADERS);
    }

    if (r->method & NGX_HTTP_OPTIONS) {
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_OK, NULL);
    }

    // only accept GET, POST, PUT and DELETE methods if enable publisher administration
    if ((cf->location_type == NGX_HTTP_PUSH_STREAM_PUBLISHER_MODE_ADMIN) && !(r->method & (NGX_HTTP_GET|NGX_HTTP_POST|NGX_HTTP_PUT|NGX_HTTP_DELETE))) {
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ALLOW, &NGX_HTTP_PUSH_STREAM_ALLOW_GET_POST_PUT_DELETE_METHODS);
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_NOT_ALLOWED, NULL);
    }

    // only accept GET, POST and PUT methods if NOT enable publisher administration
    if ((cf->location_type != NGX_HTTP_PUSH_STREAM_PUBLISHER_MODE_ADMIN) && !(r->method & (NGX_HTTP_GET|NGX_HTTP_POST|NGX_HTTP_PUT))) {
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ALLOW, &NGX_HTTP_PUSH_STREAM_ALLOW_GET_POST_PUT_METHODS);
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_NOT_ALLOWED, NULL);
    }

    if ((ctx = ngx_http_push_stream_add_request_context(r)) == NULL) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: unable to create request context");
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_INTERNAL_SERVER_ERROR, NULL);
    }

    //get channels ids
    requested_channels = ngx_http_push_stream_parse_channels_ids_from_path(r, r->pool);
    if ((requested_channels == NULL) || ngx_queue_empty(&requested_channels->queue)) {
        ngx_log_error(NGX_LOG_WARN, r->connection->log, 0, "push stream module: the push_stream_channels_path is required but is not set");
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_BAD_REQUEST, &NGX_HTTP_PUSH_STREAM_NO_CHANNEL_ID_MESSAGE);
    }

    for (q = ngx_queue_head(&requested_channels->queue); q != ngx_queue_sentinel(&requested_channels->queue); q = ngx_queue_next(q)) {
        requested_channel = ngx_queue_data(q, ngx_http_push_stream_requested_channel_t, queue);

        // check if channel id isn't equals to ALL or contain wildcard
        if ((ngx_memn2cmp(requested_channel->id->data, NGX_HTTP_PUSH_STREAM_ALL_CHANNELS_INFO_ID.data, requested_channel->id->len, NGX_HTTP_PUSH_STREAM_ALL_CHANNELS_INFO_ID.len) == 0) || (ngx_strchr(requested_channel->id->data, '*') != NULL)) {
            return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_FORBIDDEN, &NGX_HTTP_PUSH_STREAM_CHANNEL_ID_NOT_AUTHORIZED_MESSAGE);
        }

        // could not have a large size
        if ((mcf->max_channel_id_length != NGX_CONF_UNSET_UINT) && (requested_channel->id->len > mcf->max_channel_id_length)) {
            ngx_log_error(NGX_LOG_WARN, r->connection->log, 0, "push stream module: channel id is larger than allowed %d", requested_channel->id->len);
            return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_BAD_REQUEST, &NGX_HTTP_PUSH_STREAM_TOO_LARGE_CHANNEL_ID_MESSAGE);
        }

        if (r->method & (NGX_HTTP_POST|NGX_HTTP_PUT)) {
            // create the channel if doesn't exist
            requested_channel->channel = ngx_http_push_stream_get_channel(requested_channel->id, r->connection->log, mcf);
            if (requested_channel->channel == NULL) {
                return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_INTERNAL_SERVER_ERROR, NULL);
            }

            if (requested_channel->channel == NGX_HTTP_PUSH_STREAM_NUMBER_OF_CHANNELS_EXCEEDED) {
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: number of channels were exceeded");
                return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_FORBIDDEN, &NGX_HTTP_PUSH_STREAM_NUMBER_OF_CHANNELS_EXCEEDED_MESSAGE);
            }
        } else {
            requested_channel->channel = ngx_http_push_stream_find_channel(requested_channel->id, r->connection->log, mcf);
        }

        if ((r->method != NGX_HTTP_GET) && (requested_channel->channel != NULL) && requested_channel->channel->for_events) {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: only internal routines can change events channel");
            return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_FORBIDDEN, &NGX_HTTP_PUSH_STREAM_INTERNAL_ONLY_EVENTS_CHANNEL_MESSAGE);
        }
    }

    ctx->requested_channels = requested_channels;

    if (r->method & (NGX_HTTP_POST|NGX_HTTP_PUT)) {
        return ngx_http_push_stream_publisher_handle_after_read_body(r, ngx_http_push_stream_publisher_body_handler);
    }

    if ((cf->location_type == NGX_HTTP_PUSH_STREAM_PUBLISHER_MODE_ADMIN) && (r->method == NGX_HTTP_DELETE)) {
        return ngx_http_push_stream_publisher_handle_after_read_body(r, ngx_http_push_stream_publisher_delete_handler);
    }

    return ngx_http_push_stream_send_response_channels_info_detailed(r, requested_channels);
}
static ngx_int_t
ngx_http_push_stream_subscriber_handler(ngx_http_request_t *r)
{
    ngx_http_push_stream_main_conf_t               *mcf = ngx_http_get_module_main_conf(r, ngx_http_push_stream_module);
    ngx_http_push_stream_loc_conf_t                *cf = ngx_http_get_module_loc_conf(r, ngx_http_push_stream_module);
    ngx_http_push_stream_subscriber_t              *worker_subscriber;
    ngx_http_push_stream_requested_channel_t       *requested_channels, *requested_channel;
    ngx_queue_t                                    *q;
    ngx_http_push_stream_module_ctx_t              *ctx;
    ngx_int_t                                       tag;
    time_t                                          if_modified_since;
    ngx_str_t                                      *last_event_id = NULL;
    ngx_str_t                                      *push_mode;
    ngx_flag_t                                      polling, longpolling;
    ngx_int_t                                       status_code;
    ngx_str_t                                      *explain_error_message;
    ngx_str_t                                       vv_allowed_origins = ngx_null_string;

    // add headers to support cross domain requests
    if (cf->allowed_origins != NULL) {
        ngx_http_push_stream_complex_value(r, cf->allowed_origins, &vv_allowed_origins);
    }

    if (vv_allowed_origins.len > 0) {
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_ORIGIN, &vv_allowed_origins);
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_METHODS, &NGX_HTTP_PUSH_STREAM_ALLOW_GET);
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ACCESS_CONTROL_ALLOW_HEADERS, &NGX_HTTP_PUSH_STREAM_ALLOWED_HEADERS);
    }

    if (r->method & NGX_HTTP_OPTIONS) {
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_OK, NULL);
    }

    ngx_http_push_stream_set_expires(r, NGX_HTTP_PUSH_STREAM_EXPIRES_EPOCH, 0);

    // only accept GET method
    if (!(r->method & NGX_HTTP_GET)) {
        ngx_http_push_stream_add_response_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_ALLOW, &NGX_HTTP_PUSH_STREAM_ALLOW_GET);
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_NOT_ALLOWED, NULL);
    }

    if ((ctx = ngx_http_push_stream_add_request_context(r)) == NULL) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: unable to create request context");
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    //get channels ids and backtracks from path
    requested_channels = ngx_http_push_stream_parse_channels_ids_from_path(r, r->pool);
    if ((requested_channels == NULL) || ngx_queue_empty(&requested_channels->queue)) {
        ngx_log_error(NGX_LOG_WARN, r->connection->log, 0, "push stream module: the push_stream_channels_path is required but is not set");
        return ngx_http_push_stream_send_only_header_response(r, NGX_HTTP_BAD_REQUEST, &NGX_HTTP_PUSH_STREAM_NO_CHANNEL_ID_MESSAGE);
    }

    //validate channels: name, length and quantity. check if channel exists when authorized_channels_only is on. check if channel is full of subscribers
    if (ngx_http_push_stream_validate_channels(r, requested_channels, &status_code, &explain_error_message) == NGX_ERROR) {
        return ngx_http_push_stream_send_only_header_response(r, status_code, explain_error_message);
    }

    // get control values
    ngx_http_push_stream_get_last_received_message_values(r, &if_modified_since, &tag, &last_event_id);

    push_mode = ngx_http_push_stream_get_header(r, &NGX_HTTP_PUSH_STREAM_HEADER_MODE);
    polling = ((cf->location_type == NGX_HTTP_PUSH_STREAM_SUBSCRIBER_MODE_POLLING) || ((push_mode != NULL) && (push_mode->len == NGX_HTTP_PUSH_STREAM_MODE_POLLING.len) && (ngx_strncasecmp(push_mode->data, NGX_HTTP_PUSH_STREAM_MODE_POLLING.data, NGX_HTTP_PUSH_STREAM_MODE_POLLING.len) == 0)));
    longpolling = ((cf->location_type == NGX_HTTP_PUSH_STREAM_SUBSCRIBER_MODE_LONGPOLLING) || ((push_mode != NULL) && (push_mode->len == NGX_HTTP_PUSH_STREAM_MODE_LONGPOLLING.len) && (ngx_strncasecmp(push_mode->data, NGX_HTTP_PUSH_STREAM_MODE_LONGPOLLING.data, NGX_HTTP_PUSH_STREAM_MODE_LONGPOLLING.len) == 0)));

    if (polling || longpolling) {
        ngx_int_t result = ngx_http_push_stream_subscriber_polling_handler(r, requested_channels, if_modified_since, tag, last_event_id, longpolling, ctx->temp_pool);
        if (ctx->temp_pool != NULL) {
            ngx_destroy_pool(ctx->temp_pool);
            ctx->temp_pool = NULL;
        }
        return result;
    }

    ctx->padding = ngx_http_push_stream_get_padding_by_user_agent(r);

    // stream access
    if ((worker_subscriber = ngx_http_push_stream_subscriber_prepare_request_to_keep_connected(r)) == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    ngx_http_send_header(r);

    // sending response content header
    if (ngx_http_push_stream_send_response_content_header(r, cf) == NGX_ERROR) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "push stream module: could not send content header to subscriber");
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    if (ngx_http_push_stream_registry_subscriber(r, worker_subscriber) == NGX_ERROR) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    // adding subscriber to channel(s) and send old messages
    for (q = ngx_queue_head(&requested_channels->queue); q != ngx_queue_sentinel(&requested_channels->queue); q = ngx_queue_next(q)) {
        requested_channel = ngx_queue_data(q, ngx_http_push_stream_requested_channel_t, queue);

        if (ngx_http_push_stream_subscriber_assign_channel(mcf, cf, r, requested_channel, if_modified_since, tag, last_event_id, worker_subscriber, ctx->temp_pool) != NGX_OK) {
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    }

    if (ctx->temp_pool != NULL) {
        ngx_destroy_pool(ctx->temp_pool);
        ctx->temp_pool = NULL;
    }
    return NGX_DONE;
}