falco/userspace/falco/webserver.cpp

/*
Copyright (C) 2022 The Falco Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

#include "webserver.h"
#include "falco_utils.h"
#include <atomic>

falco_webserver::~falco_webserver()
{
    stop();
}

void falco_webserver::start(
        uint32_t threadiness,
        uint32_t listen_port,
        std::string& healthz_endpoint,
        std::string &ssl_certificate,
        bool ssl_enabled)
{
    if (m_running)
    {
        throw falco_exception(
            "attempted restarting webserver without stopping it first");
    }

    // allocate and configure server
    if (ssl_enabled)
    {
        m_server = new httplib::SSLServer(
            ssl_certificate.c_str(),
            ssl_certificate.c_str());
    }
    else
    {
        m_server = new httplib::Server();
    }

    // configure server
    m_server->new_task_queue = [&threadiness] { return new httplib::ThreadPool(threadiness); };

    // setup healthz endpoint
    m_server->Get(healthz_endpoint,
        [](const httplib::Request &, httplib::Response &res) {
            res.set_content("{\"status\": \"ok\"}", "application/json");
        });

    // run server in a separate thread
    if (!m_server->is_valid())
    {
        delete m_server;
        m_server = NULL;
        throw falco_exception("invalid webserver configuration");
    }

    std::atomic<bool> failed;
    failed.store(false, std::memory_order_release);
    m_server_thread = std::thread([this, listen_port, &failed]
    {
        try
        {
            this->m_server->listen("0.0.0.0", listen_port);
        }
        catch(std::exception &e)
        {
            falco_logger::log(
                LOG_ERR,
                "falco_webserver: " + string(e.what()) + "\n");
        }
        failed.store(true, std::memory_order_release);
    });

    // wait for the server to actually start up
    // note: is_running() is atomic
    while (!m_server->is_running() && !failed.load(std::memory_order_acquire))
    {
        std::this_thread::yield();
    }
    m_running = true;
    if (failed.load(std::memory_order_acquire))
    {
        stop();
        throw falco_exception("an error occurred while starting webserver");
    }
}

void falco_webserver::stop()
{
    if (m_running)
    {
        if (m_server != NULL)
        {
            m_server->stop();
        }
        if(m_server_thread.joinable())
        {
            m_server_thread.join();
        }
        if (m_server != NULL)
        {
            delete m_server;
            m_server = NULL;
        }
        m_running = false;
    }
}