GitHub - kamchatka-volcano/asyncgi: An asynchronous FastCGI web microframework for C++

asyncgi - is a C++17 asynchronous microframework for creating web applications interfacing with any HTTP server supporting FastCGI protocol. It aims to provide a modern way of using CGI, with a custom performant FastCGI implementation in C++, multithreading support and a clean and simple API:

#include <asyncgi/asyncgi.h>

namespace http = asyncgi::http;

int main()
{
    auto io = asyncgi::IO{};
    auto router = asyncgi::Router{io};
    router.route("/", http::RequestMethod::Get).process(
        [](const asyncgi::Request&)
        {
            return http::Response{"Hello world"};
        });

    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

Usage

Connection

Web applications developed with asyncgi require to establish a FastCGI connection with a web server handling HTTP requests. Most popular servers provide this functionality, for example NGINX can be used with a following configuration:

server {
	listen 8088;
	server_name localhost;
	
	location / {
		try_files $uri @fcgi;
	}
	
	location @fcgi {	
		fastcgi_pass  unix:/tmp/fcgi.sock;		
		#or using a TCP socket
		#fastcgi_pass localhost:9000;
		include fastcgi_params;
	}
}

asyncgi supports both UNIX domain and TCP sockets for opening FastCGI connections.

Request processor

In order to process requests, it's necessary to provide a function or function object that fulfills the RequestProcessor requirement. This means that the function must be invocable with one of the following signatures:

http::Response (const asyncgi::Request&)
void (const asyncgi::Request&, asyncgi::Responder&).

Example

///examples/example_request_processor.cpp
///
#include <asyncgi/asyncgi.h>

namespace http = asyncgi::http;

http::Response guestBookPage(const asyncgi::Request& request)
{
    if (request.path() == "/")
        return {R"(
                <h1>Guest book</h1>
                <p>No messages</p>
            )"};

    return http::ResponseStatus::_404_Not_Found;
}

int main()
{
    auto io = asyncgi::IO{};
    auto server = asyncgi::Server{io, guestBookPage};
    //Listen for FastCGI connections on UNIX domain socket
    server.listen("/tmp/fcgi.sock");
    //or over TCP
    //server.listen("127.0.0.1", 9088);
    io.run();
    return 0;
}

Here, the guestBookPage function serves as the request processor. Another way to implement it is by accepting a reference to the asyncgi::Responder object, which can be used for sending responses manually:

void guestBookPage(const asyncgi::Request& request, asyncgi::Responder& responder)
{
    if (request.path() == "/")
        responder.send(R"(
                <h1>Guest book</h1>
                <p>No messages</p>
            )");

    return responder.send(http::ResponseStatus::_404_Not_Found);
}

This approach tends to be more verbose and error-prone, therefore it is preferable to use it only when access to asyncgi::Responder is required for initiating asynchronous operations from the request processor. These cases are covered in the later parts of this document.

Router

Multiple request processors can be registered in the asyncgi::Router object, where they are matched to the paths specified in requests. The asyncgi::Router itself satisfies the RequestProcessor requirement.

If multiple threads are required for request processing, the desired number of workers can be passed to the asyncgi::IO object's constructor. In such cases, the user must ensure that any shared data in the request processors is protected from concurrent read/write access.

Example

///examples/example_router.cpp
///
#include <asyncgi/asyncgi.h>
#include <mutex>

namespace http = asyncgi::http;
using namespace std::string_literals;

class GuestBookState {
public:
    std::vector<std::string> messages()
    {
        auto lock = std::scoped_lock{mutex_};
        return messages_;
    }

    void addMessage(const std::string& msg)
    {
        auto lock = std::scoped_lock{mutex_};
        messages_.emplace_back(msg);
    }

private:
    std::vector<std::string> messages_;
    std::mutex mutex_;
};

class GuestBookPage {
public:
    GuestBookPage(GuestBookState& state)
        : state_(&state)
    {
    }

    http::Response operator()(const asyncgi::Request&)
    {
        auto messages = state_->messages();
        auto page = "<h1>Guest book</h1>"s;
        if (messages.empty())
            page += "<p>No messages</p>";
        else
            for (const auto& msg : messages)
                page += "<p>" + msg + "</p>";

        page += "<hr>";
        page += "<form method=\"post\" enctype=\"multipart/form-data\">"
                "<label for=\"msg\">Message:</label>"
                "<input id=\"msg\" name=\"msg\" value=\"\">"
                "<input value=\"Submit\" data-popup=\"true\" type=\"submit\">"
                "</form>";
        return page;
    }

private:
    GuestBookState* state_;
};

class GuestBookAddMessage {
public:
    GuestBookAddMessage(GuestBookState& state)
        : state_(&state)
    {
    }

    http::Response operator()(const asyncgi::Request& request)
    {
        state_->addMessage(std::string{request.formField("msg")});
        return http::Redirect{"/"};
    }

private:
    GuestBookState* state_;
};

int main()
{
    auto io = asyncgi::IO{4}; //4 threads processing requests
    auto state = GuestBookState{};
    auto router = asyncgi::Router{io};
    router.route("/", http::RequestMethod::Get).process<GuestBookPage>(state);
    router.route("/", http::RequestMethod::Post).process<GuestBookAddMessage>(state);
    router.route().set(http::Response{http::ResponseStatus::_404_Not_Found, "Page not found"});
    //Alternatively, it's possible to pass arguments for creation of http::Response object to the set() method.
    //router.route().set(http::ResponseStatus::Code_404_Not_Found, "Page not found");

    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

Route parameters

When using asyncgi::Router with regular expressions, request processors must satisfy the ParametrizedRequestProcessor requirement. That means that a function object must be invocable with one of the following signatures:

http::Response void(const TRouteParams&..., const asyncgi::Request&)
void (const TRouteParams&..., const asyncgi::Request&, asyncgi::Responder&)

The TRouteParams represents zero or more parameters generated from the capturing groups of the regular expression. For example, http::Response (int age, string name, const asyncgi::Request&) signature can be used to process requests matched by asyncgi::rx{"/person/(\\w+)/age/(\\d+)"}.

In the following example a ParametrizedRequestProcessor named GuestBookRemoveMessage is added to remove the stored guest book messages:

Example

///examples/example_route_params.cpp
///
#include <asyncgi/asyncgi.h>
#include <mutex>

using namespace asyncgi;
using namespace std::string_literals;

class GuestBookState {
public:
    std::vector<std::string> messages()
    {
        auto lock = std::scoped_lock{mutex_};
        return messages_;
    }

    void addMessage(const std::string& msg)
    {
        auto lock = std::scoped_lock{mutex_};
        messages_.emplace_back(msg);
    }

    void removeMessage(int index)
    {
        auto lock = std::scoped_lock{mutex_};
        if (index < 0 || index >= static_cast<int>(messages_.size()))
            return;
        messages_.erase(std::next(messages_.begin(), index));
    }

private:
    std::vector<std::string> messages_;
    std::mutex mutex_;
};

std::string makeMessage(int index, const std::string& msg)
{
    return msg + R"(<form action="/delete/)" + std::to_string(index) +
            R"(" method="post"> <input value="Delete" type="submit"> </form></div>)";
}

class GuestBookPage {
public:
    explicit GuestBookPage(GuestBookState& state)
        : state_{&state}
    {
    }

    http::Response operator()(const asyncgi::Request&)
    {
        auto messages = state_->messages();
        auto page = "<h1>Guest book</h1>"s;
        if (messages.empty())
            page += "<p>No messages</p>";
        else
            for (auto i = 0; i < static_cast<int>(messages.size()); ++i)
                page += "<p>" + makeMessage(i, messages.at(i)) + "</p>";

        page += "<hr>";
        page += "<form method=\"post\" enctype=\"multipart/form-data\">"
                "<label for=\"msg\">Message:</label>"
                "<input id=\"msg\" name=\"msg\" value=\"\">"
                "<input value=\"Submit\" data-popup=\"true\" type=\"submit\">"
                "</form>";
        return page;
    }

private:
    GuestBookState* state_;
};

class GuestBookAddMessage {
public:
    explicit GuestBookAddMessage(GuestBookState& state)
        : state_{&state}
    {
    }

    http::Response operator()(const asyncgi::Request& request)
    {
        state_->addMessage(std::string{request.formField("msg")});
        return http::Redirect{"/"};
    }

private:
    GuestBookState* state_;
};

class GuestBookRemoveMessage {
public:
    explicit GuestBookRemoveMessage(GuestBookState& state)
        : state_{&state}
    {
    }

    http::Response operator()(int index, const asyncgi::Request&)
    {
        state_->removeMessage(index);
        return http::Redirect{"/"};
    }

private:
    GuestBookState* state_;
};

int main()
{
    auto io = asyncgi::IO{4};
    auto state = GuestBookState{};
    auto router = asyncgi::Router{io};
    router.route("/", http::RequestMethod::Get).process<GuestBookPage>(state);
    router.route("/", http::RequestMethod::Post).process<GuestBookAddMessage>(state);
    router.route(asyncgi::rx{"/delete/(.+)"}, http::RequestMethod::Post).process<GuestBookRemoveMessage>(state);
    router.route().set(http::ResponseStatus::_404_Not_Found, "Page not found");

    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

Regular expression capture groups are transformed into request processor arguments using std::stringstream. In order to support request processors with user-defined parameter types, it is necessary to provide a specialization of asyncgi::config::StringConverter class template. The previous example has been modified to reformat the GuestBookRemoveMessage request processor to use the MessageNumber structure as a request processor argument:

Example

///examples/example_route_params_user_defined_types.cpp
///
#include <asyncgi/asyncgi.h>
#include <mutex>

using namespace asyncgi;
using namespace std::string_literals;

struct MessageNumber {
    int value;
};

template<>
struct asyncgi::config::StringConverter<MessageNumber> {
    static std::optional<MessageNumber> fromString(const std::string& data)
    {
        return MessageNumber{std::stoi(data)};
    }
};

class GuestBookState {
public:
    std::vector<std::string> messages()
    {
        auto lock = std::scoped_lock{mutex_};
        return messages_;
    }

    void addMessage(const std::string& msg)
    {
        auto lock = std::scoped_lock{mutex_};
        messages_.emplace_back(msg);
    }

    void removeMessage(int index)
    {
        auto lock = std::scoped_lock{mutex_};
        if (index < 0 || index >= static_cast<int>(messages_.size()))
            return;
        messages_.erase(std::next(messages_.begin(), index));
    }

private:
    std::vector<std::string> messages_;
    std::mutex mutex_;
};

std::string makeMessage(int index, const std::string& msg)
{
    return msg + R"(<form action="/delete/)" + std::to_string(index) +
            R"(" method="post"> <input value="Delete" type="submit"> </form></div>)";
}

class GuestBookPage {
public:
    explicit GuestBookPage(GuestBookState& state)
        : state_{&state}
    {
    }

    http::Response operator()(const asyncgi::Request&)
    {
        auto messages = state_->messages();
        auto page = "<h1>Guest book</h1>"s;
        if (messages.empty())
            page += "<p>No messages</p>";
        else
            for (auto i = 0; i < static_cast<int>(messages.size()); ++i)
                page += "<p>" + makeMessage(i, messages.at(i)) + "</p>";

        page += "<hr>";
        page += "<form method=\"post\" enctype=\"multipart/form-data\">"
                "<label for=\"msg\">Message:</label>"
                "<input id=\"msg\" name=\"msg\" value=\"\">"
                "<input value=\"Submit\" data-popup=\"true\" type=\"submit\">"
                "</form>";
        return page;
    }

private:
    GuestBookState* state_;
};

class GuestBookAddMessage {
public:
    explicit GuestBookAddMessage(GuestBookState& state)
        : state_{&state}
    {
    }

    http::Response operator()(const asyncgi::Request& request)
    {
        state_->addMessage(std::string{request.formField("msg")});
        return http::Redirect{"/"};
    }

private:
    GuestBookState* state_;
};

class GuestBookRemoveMessage {
public:
    explicit GuestBookRemoveMessage(GuestBookState& state)
        : state_{&state}
    {
    }

    http::Response operator()(MessageNumber msgNumber, const asyncgi::Request&)
    {
        state_->removeMessage(msgNumber.value);
        return http::Redirect{"/"};
    }

private:
    GuestBookState* state_;
};

int main()
{
    auto io = asyncgi::IO{4};
    auto state = GuestBookState{};
    auto router = asyncgi::Router{io};
    router.route("/", http::RequestMethod::Get).process<GuestBookPage>(state);
    router.route("/", http::RequestMethod::Post).process<GuestBookAddMessage>(state);
    router.route(asyncgi::rx{"/delete/(.+)"}, http::RequestMethod::Post).process<GuestBookRemoveMessage>(state);
    router.route().set(http::ResponseStatus::_404_Not_Found, "Page not found");

    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

Route context

When using asyncgi::Router, it is possible to specify a template argument for a context structure type. This structure is then passed to the ContextualRequestProcessor functions and can be accessed and modified throughout the request processing for multiple routes. The ContextualRequestProcessor is a RequestProcessor that takes an additional argument referring to the context object.
A single request can match multiple routes, as long as all preceding request processors do not send any response. To avoid sending responses request processors can use the std::optional<http::Response> signature and return empty values. This allows using asyncgi::Router to register middleware-like processors, which primarily modify the route context for subsequent processors.

The next example demonstrates how a route context can be used for storing authorization information:

Example

///examples/example_route_context.cpp
///
#include <asyncgi/asyncgi.h>
#include <mutex>
#include <optional>

namespace http = asyncgi::http;
using namespace std::string_literals;

enum class AccessRole {
    Admin,
    Guest
};

struct RouteContext {
    AccessRole role = AccessRole::Guest;
};

struct AdminAuthorizer {
    std::optional<http::Response> operator()(const asyncgi::Request& request, RouteContext& context)
    {
        if (request.cookie("admin_id") == "ADMIN_SECRET")
            context.role = AccessRole::Admin;

        return std::nullopt;
    }
};

struct LoginPage {
    http::Response operator()(const asyncgi::Request&, RouteContext& context)
    {
        if (context.role == AccessRole::Guest)
            return {R"(
                    <html>
                    <form method="post" enctype="multipart/form-data">
                    <label for="msg">Login:</label>
                    <input id="login" name="login" value="">
                    <label for="msg">Password:</label>
                    <input id="passwd" name="passwd" value="">
                    <input value="Submit" data-popup="true" type="submit">
                    </form></html>)"};
        else //We are already logged in as the administrator
            return http::Redirect{"/"};
    }
};

struct LoginPageAuthorize {
    http::Response operator()(const asyncgi::Request& request, RouteContext& context)
    {
        if (context.role == AccessRole::Guest) {
            if (request.formField("login") == "admin" && request.formField("passwd") == "12345")
                return {http::Redirect{"/"}, {asyncgi::http::Cookie("admin_id", "ADMIN_SECRET")}};
            else
                return http::Redirect{"/login"};
        }
        else //We are already logged in as the administrator
            return http::Redirect{"/"};
    }
};

int main()
{
    auto io = asyncgi::IO{4}; //4 threads processing requests
    auto router = asyncgi::Router<RouteContext>{io};
    router.route(asyncgi::rx{".*"}).process<AdminAuthorizer>();
    router.route("/").process(
            [](const asyncgi::Request&, asyncgi::Responder& response, RouteContext& context)
            {
                if (context.role == AccessRole::Admin)
                    response.send("<p>Hello admin</p>");
                else
                    response.send(R"(<p>Hello guest</p><p><a href="/login">login</a>)");
            });

    router.route("/login", http::RequestMethod::Get).process<LoginPage>();
    router.route("/login", http::RequestMethod::Post).process<LoginPageAuthorize>();
    router.route().set(http::ResponseStatus::_404_Not_Found, "Page not found");

    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

Route matchers

Any parameter of request or context objects can be registered for route matching in asyncgi::Router::route() method. To achieve this, it is required to provide a specialization of the asyncgi::config::RouteMatcher class template and implement a comparator bool operator() within it. Let's see how to register the enum class Access from the previous example as a route matcher:

Example

///examples/example_route_matcher.cpp
///
#include <asyncgi/asyncgi.h>
#include <mutex>
#include <optional>

namespace http = asyncgi::http;
using namespace std::string_literals;

enum class AccessRole {
    Admin,
    Guest
};

struct RouteContext {
    AccessRole role = AccessRole::Guest;
};

struct AdminAuthorizer {
    std::optional<http::Response> operator()(const asyncgi::Request& request, RouteContext& context)
    {
        if (request.cookie("admin_id") == "ADMIN_SECRET")
            context.role = AccessRole::Admin;

        return std::nullopt;
    }
};

struct LoginPage {
    http::Response operator()(const asyncgi::Request&)
    {
        return {R"(
                <html>
                <form method="post" enctype="multipart/form-data">
                <label for="msg">Login:</label>
                <input id="login" name="login" value="">
                <label for="msg">Password:</label>
                <input id="passwd" name="passwd" value="">
                <input value="Submit" data-popup="true" type="submit">
                </form></html>)"};
    }
};

struct LoginPageAuthorize {
    http::Response operator()(const asyncgi::Request& request)
    {
        if (request.formField("login") == "admin" && request.formField("passwd") == "12345")
            return {http::Redirect{"/"}, {asyncgi::http::Cookie("admin_id", "ADMIN_SECRET")}};

        return http::Redirect{"/login"};
    }
};

template<>
struct asyncgi::config::RouteMatcher<AccessRole, RouteContext> {
    bool operator()(AccessRole value, const asyncgi::Request&, const RouteContext& context) const
    {
        return value == context.role;
    }
};

int main()
{
    auto io = asyncgi::IO{4};
    auto router = asyncgi::Router<RouteContext>{io};
    router.route(asyncgi::rx{".*"}).process<AdminAuthorizer>();
    router.route("/").process(
            [](const asyncgi::Request&, RouteContext& context) -> http::Response
            {
                if (context.role == AccessRole::Admin)
                    return {"<p>Hello admin</p>"};
                else
                    return {R"(<p>Hello guest</p><p><a href="/login">login</a>)"};
            });

    router.route("/login", http::RequestMethod::Get, AccessRole::Guest).process<LoginPage>();
    router.route("/login", http::RequestMethod::Post, AccessRole::Guest).process<LoginPageAuthorize>();
    router.route("/login", http::RequestMethod::Get, AccessRole::Admin).set("/", http::RedirectType::Found);
    router.route("/login", http::RequestMethod::Post, AccessRole::Admin).set("/", http::RedirectType::Found);
    router.route().set(http::ResponseStatus::_404_Not_Found, "Page not found");

    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

Complete guest book example

Let's combine all the previous examples to create a simple guest book.
The messages in the guest book will only persist during the application runtime, as they are stored in a std::vector. The admin credentials for logging in are as follows: login: admin, password: 12345. The admin account has the ability to delete posts.

Example

///examples/example_guestbook.cpp
///
#include <asyncgi/asyncgi.h>
#include <mutex>
#include <optional>
#include <regex>

namespace http = asyncgi::http;
using namespace std::string_literals;

enum class AccessRole {
    Admin,
    Guest
};

struct RouteContext {
    AccessRole role = AccessRole::Guest;
};

template<>
struct asyncgi::config::RouteMatcher<AccessRole, RouteContext> {
    bool operator()(AccessRole value, const asyncgi::Request&, const RouteContext& context) const
    {
        return value == context.role;
    }
};

std::optional<http::Response> authorizeAdmin(const asyncgi::Request& request, RouteContext& context)
{
    if (request.cookie("admin_id") == "ADMIN_SECRET")
        context.role = AccessRole::Admin;

    return std::nullopt;
}

http::Response showLoginPage(const asyncgi::Request&)
{
    return {R"(
            <head><link rel="stylesheet" href="https://cdn.simplecss.org/simple.min.css"></head>
            <form method="post" enctype="multipart/form-data">
                <label for="msg">Login:</label>
                <input id="login" name="login" value="">
                <label for="msg">Password:</label>
                <input id="passwd" name="passwd" value="">
                <input value="Submit" data-popup="true" type="submit">
            </form>)"};
}

http::Response loginAdmin(const asyncgi::Request& request)
{
    if (request.formField("login") == "admin" && request.formField("passwd") == "12345")
        return {http::Redirect{"/"}, {http::Cookie("admin_id", "ADMIN_SECRET")}};
    else
        return http::Redirect{"/login"};
}

http::Response logoutAdmin(const asyncgi::Request&)
{
    return {http::Redirect{"/"}, {http::Cookie("admin_id", "")}};
}

struct GuestBookMessage {
    std::string name;
    std::string text;
};

class GuestBookState {
public:
    std::vector<GuestBookMessage> messages()
    {
        auto lock = std::scoped_lock{mutex_};
        return messages_;
    }

    void addMessage(std::string name, std::string msg)
    {
        name = std::regex_replace(name, std::regex{"<"}, "&lt;");
        name = std::regex_replace(name, std::regex{">"}, "&gt;");
        msg = std::regex_replace(msg, std::regex{"<"}, "&lt;");
        msg = std::regex_replace(msg, std::regex{">"}, "&gt;");
        auto lock = std::scoped_lock{mutex_};
        messages_.emplace_back(GuestBookMessage{name.empty() ? "Guest" : name, msg});
    }

    void removeMessage(int index)
    {
        auto lock = std::scoped_lock{mutex_};
        if (index < 0 || index >= static_cast<int>(messages_.size()))
            return;
        messages_.erase(std::next(messages_.begin(), index));
    }

private:
    std::vector<GuestBookMessage> messages_;
    std::mutex mutex_;
};

std::string makeMessagesDiv(const std::vector<GuestBookMessage>& messages, AccessRole role)
{
    if (messages.empty())
        return "<div>No messages</div>";

    auto messagesDiv = std::string{};
    for (auto i = 0; i < static_cast<int>(messages.size()); ++i) {
        messagesDiv += "<h4>" + messages.at(i).name + " says:</hr><pre>" + messages.at(i).text + "</pre>";
        if (role == AccessRole::Admin)
            messagesDiv += R"(<form action="/delete/)" + std::to_string(i) +
                    R"(" method="post"> <input value="Delete" type="submit"></form>)";
    }
    return messagesDiv;
}

std::string makeLinksDiv(AccessRole role)
{
    return (role == AccessRole::Admin ? R"(<a href="/logout">logout</a>&nbsp;)"s
                                      : R"(<a href="/login">login</a>&nbsp;)"s) +
            R"(<a href="https://github.com/kamchatka-volcano/asyncgi/blob/master/examples/example_guestbook.cpp">source</a></div>)"s;
}

auto showGuestBookPage(GuestBookState& state)
{
    return [&state](const asyncgi::Request& request, RouteContext& context) -> http::Response
    {
        auto page = R"(<head><link rel="stylesheet" href="https://cdn.simplecss.org/simple.min.css"></head>
                       <div style="display:flex; flex-direction: row; justify-content: flex-end">%LINKS%</div>
                       <div style="display:flex; flex-direction: column; height: calc(100vh - 5em);">
                           <h1>asyncgi guest book</h1>
                           <div style="flex: 1; min-height: 0; display:flex; flex-direction: column;">
                               <div style="flex:1; overflow-y: auto; row-gap: 60px">
                                    %MESSAGES%
                               </div>
                           </div>
                           <hr>
                           <div>
                                %ERROR_MSG%
                               <form style="display:flex; flex-direction: column; width:66%;" method="post" enctype="multipart/form-data">
                                   <label for="name">Name:</label>
                                   <input id="name" name="name" style="width:50%">
                                   <textarea style="min-height:5em; resize:none;" name="msg" id="msg" maxlength="4192" autocomplete="off"></textarea>
                                   <div style="display:flex; flex-direction: row; justify-content: flex-end">
                                      <input value="Submit" data-popup="true" type="submit" style="width:33%"></td>
                                   </div>
                               </form>
                           </div>
                       </div>)"s;

        page = std::regex_replace(page, std::regex{"%MESSAGES%"}, makeMessagesDiv(state.messages(), context.role));
        page = std::regex_replace(page, std::regex{"%LINKS%"}, makeLinksDiv(context.role));
        if (request.hasQuery("error")) {
            if (request.query("error") == "urls_in_msg")
                page = std::regex_replace(page, std::regex{"%ERROR_MSG%"}, "<mark>Messages can't contain urls</mark>");
            if (request.query("error") == "empty_msg")
                page = std::regex_replace(page, std::regex{"%ERROR_MSG%"}, "<mark>Messages can't be empty</mark>");
        }
        else
            page = std::regex_replace(page, std::regex{"%ERROR_MSG%"}, "");

        return page;
    };
}

auto addMessage(GuestBookState& state)
{
    return [&state](const asyncgi::Request& request) -> http::Response
    {
        if (std::all_of(
                    request.formField("msg").begin(),
                    request.formField("msg").end(),
                    [](char ch)
                    {
                        return std::isspace(static_cast<unsigned char>(ch));
                    }))
            return http::Redirect{"/?error=empty_msg"};
        else if (
                request.formField("msg").find("http://") != std::string_view::npos ||
                request.formField("msg").find("https://") != std::string_view::npos)
            return http::Redirect{"/?error=urls_in_msg"};
        else {
            state.addMessage(std::string{request.formField("name")}, std::string{request.formField("msg")});
            return http::Redirect{"/"};
        }
    };
}

auto removeMessage(GuestBookState& state)
{
    return [&state](int index, const asyncgi::Request&) -> http::Response
    {
        state.removeMessage(index);
        return http::Redirect{"/"};
    };
}

int main()
{
    auto io = asyncgi::IO{4};
    auto state = GuestBookState{};
    auto router = asyncgi::Router<RouteContext>{io};
    router.route(asyncgi::rx{".*"}).process(authorizeAdmin);
    router.route("/", http::RequestMethod::Get).process(showGuestBookPage(state));
    router.route("/", http::RequestMethod::Post).process(addMessage(state));
    router.route(asyncgi::rx{"/delete/(.+)"}, http::RequestMethod::Post, AccessRole::Admin)
            .process(removeMessage(state));
    router.route(asyncgi::rx{"/delete/(.+)"}, http::RequestMethod::Post, AccessRole::Guest)
            .set(http::ResponseStatus::_401_Unauthorized);
    router.route("/login", http::RequestMethod::Get, AccessRole::Guest).process(showLoginPage);
    router.route("/login", http::RequestMethod::Post, AccessRole::Guest).process(loginAdmin);
    router.route("/logout").process(logoutAdmin);
    router.route().set(http::ResponseStatus::_404_Not_Found, "Page not found");

    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

The live demo can be accessed here.

Timer

A timer object asyncgi::Timer can be created to change or check some state periodically.

Example

///examples/example_timer.cpp
///
#include <asyncgi/asyncgi.h>

namespace http = asyncgi::http;

struct Greeter{
    Greeter(const int& secondsCounter)
        : secondsCounter_{&secondsCounter}
    {
    }

    http::Response operator()(const asyncgi::Request&)
    {
        return "Hello world\n(alive for " + std::to_string(*secondsCounter_) + " seconds)";
    }

private:
    const int* secondsCounter_;
};

int main()
{
    auto io = asyncgi::IO{};
    int secondsCounter = 0;

    auto timer = asyncgi::Timer{io};
    timer.startPeriodic(
            std::chrono::seconds(1),
            [&secondsCounter]()
            {
                ++secondsCounter;
            });

    auto router = asyncgi::Router{io};
    router.route("/").process<Greeter>(secondsCounter);
    router.route().set(http::ResponseStatus::_404_Not_Found);

    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

The asyncgi::Timer::waitFuture method can accept an std::future object and invoke a provided callable object with its result when the future object becomes ready. This function does not block while waiting and uses an internal timer to periodically check the state of the future. To use it during request processing, a timer object created from an asyncgi::Responder reference must be used. It is important to avoid using this timer after the response has already been sent.

Example

///examples/response_wait_future.cpp
///
#include <asyncgi/asyncgi.h>
#include <thread>

using namespace asyncgi;

struct DelayedPage{
    void operator()(const asyncgi::Request&, asyncgi::Responder& responder)
    {
        auto timer = asyncgi::Timer{responder};
        timer.waitFuture(
                std::async(
                        std::launch::async,
                        []
                        {
                            std::this_thread::sleep_for(std::chrono::seconds(3));
                            return "world";
                        }),
                [responder](const std::string& result) mutable
                {
                    responder.send(http::Response{"Hello " + result});
                });
    }
};

int main()
{
    auto io = asyncgi::IO{};
    auto router = asyncgi::Router{io};
    auto delayedPage = DelayedPage{};
    router.route("/", http::RequestMethod::Get).process(delayedPage);
    router.route().set(http::ResponseStatus::_404_Not_Found);
    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

Client

With asyncgi::Client it's possible to make direct requests to FastCGI applications. This enables multiple asyncgi-based applications to communicate with each other without the need for other inter-process communication solutions.

Example

///examples/example_client.cpp
///
#include <asyncgi/asyncgi.h>
#include <iostream>

using namespace asyncgi;

int main()
{
    auto io = asyncgi::IO{};
    auto client = asyncgi::Client{io};
    client.makeRequest(
            "/tmp/fcgi.sock",
            http::Request{http::RequestMethod::Get, "/"},
            [&io](const std::optional<http::ResponseView>& response)
            {
                if (response)
                    std::cout << response->body() << std::endl;
                else
                    std::cout << "No response" << std::endl;
                io.stop();
            });
    io.run();
}

To make FastCGI requests during request processing, a client object created from an asyncgi::Responder reference must be used. It is important to avoid using this client object after the response has already been sent.

Example

///examples/example_client_in_processor.cpp
///
#include <asyncgi/asyncgi.h>

namespace http = asyncgi::http;

struct RequestPage{
    void operator()(const asyncgi::Request&, asyncgi::Responder& responder)
    {
        // making request to FastCgi application listening on /tmp/fcgi.sock and showing the received response
        auto client = asyncgi::Client{responder};
        client.makeRequest(
                "/tmp/fcgi.sock",
                http::Request{http::RequestMethod::Get, "/"},
                [responder](const std::optional<http::ResponseView>& reqResponse) mutable
                {
                    if (reqResponse)
                        responder.send(std::string{reqResponse->body()});
                    else
                        responder.send("No response");
                });
    }
};

int main()
{
    auto io = asyncgi::IO{};
    auto router = asyncgi::Router{io};
    router.route("/", http::RequestMethod::Get).process<RequestPage>();
    router.route().set(http::ResponseStatus::_404_Not_Found);
    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi_client.sock");
    io.run();
}

Executing an asio task

asyncgi internally uses the asio library. A dispatcher object asyncgi::AsioDispatcher can be created to invoke callable objects that require access to the asio::io_context object.

Example

///examples/example_asio_dispatcher.cpp
///
#include <asyncgi/asyncgi.h>
#include <asio/steady_timer.hpp>
#include <iostream>

int main()
{
    auto io = asyncgi::IO{};
    auto disp = asyncgi::AsioDispatcher{io};
    disp.postTask(
            [&io](const asyncgi::TaskContext& ctx) mutable
            {
                auto timer = std::make_shared<asio::steady_timer>(ctx.io());
                timer->expires_after(std::chrono::seconds{3});
                timer->async_wait(
                        [timer, ctx, &io](auto&) mutable
                        {
                            std::cout << "Hello world" << std::endl;
                            io.stop();
                        });
            });
    io.run();
}

To invoke such a callable object during request processing, a dispatcher created from an asyncgi::Responder reference must be used. It is important to avoid using this dispatcher after the response has already been sent.

Example

///examples/example_response_dispatching_asio_task.cpp
///
#include <asyncgi/asyncgi.h>
#include <asio/steady_timer.hpp>

namespace http = asyncgi::http;

struct DelayedPage {
    void operator()(const asyncgi::Request&, asyncgi::Responder& responder)
    {
        auto disp = asyncgi::AsioDispatcher{responder};
        disp.postTask(
                [responder](const asyncgi::TaskContext& ctx) mutable
                {
                    auto timer = std::make_shared<asio::steady_timer>(ctx.io());
                    timer->expires_after(std::chrono::seconds{3});
                    timer->async_wait([timer, responder, ctx](auto&) mutable { // Note how we capture ctx object here,
                        responder.send("Hello world"); // it's necessary to keep it (or its copy) alive
                    }); // before the end of request processing
                });
    }
};

int main()
{
    auto io = asyncgi::IO{};
    auto router = asyncgi::Router{io};
    router.route("/", http::RequestMethod::Get).process<DelayedPage>();
    router.route().set(http::ResponseStatus::_404_Not_Found);
    auto server = asyncgi::Server{io, router};
    server.listen("/tmp/fcgi.sock");
    io.run();
}

To use asyncgi with the Boost.Asio library, set the ASYNCGI_USE_BOOST_ASIO CMake variable .

Showcase

stone_skipper

Development status

asyncgi is currently in the open beta stage, with all planned features complete. Until it reaches a non-zero major version number, there may be frequent introductions of backward-incompatible changes.

Unit tests are not included because most of the functionality in asyncgi is derived from the following libraries, which already have their own test coverage:

asio - used for establishing connections, sending and receiving data.
fcgi_responder - implementation of the FastCGI protocol.
whaleroute - implementation of the request router.
hot_teacup - parsing of HTTP data received over FastCGI connections, forming HTTP responses.

Instead of mocking code that integrates the functionality of these libraries, asyncgi is tested using functional tests. These tests check the behavior of the executables found in the examples/ directory when running with the NGINX server. You can find these tests in the functional_tests/ directory.

Installation

Download and link the library from your project's CMakeLists.txt:

cmake_minimum_required(VERSION 3.14)

include(FetchContent)

FetchContent_Declare(cmdlime
    GIT_REPOSITORY "https://github.com/kamchatka-volcano/asyncgi.git"
    GIT_TAG "origin/master"
)
#uncomment if you need to install cmdlime with your target
#set(INSTALL_ASYNCGI ON)
FetchContent_MakeAvailable(asyncgi)

add_executable(${PROJECT_NAME})
target_link_libraries(${PROJECT_NAME} PRIVATE asyncgi::asyncgi)

To install the library system-wide, use the following commands:

git clone https://github.com/kamchatka-volcano/asyncgi.git
cd asyncgi
cmake -S . -B build
cmake --build build
cmake --install build

After installation, you can use the find_package() command to make the installed library available inside your project:

find_package(asyncgi 0.1.0 REQUIRED)
target_link_libraries(${PROJECT_NAME} PRIVATE asyncgi::asyncgi)

If you want to use the Boost.Asio library, Boost dependencies can be resolved using vcpkg by running the build with this command:

cmake -S . -B build -DASYNCGI_USE_BOOST_ASIO=ON -DCMAKE_TOOLCHAIN_FILE=<vcpkg path>/scripts/buildsystems/vcpkg.cmake

Building examples

cd asyncgi
cmake -S . -B build -DENABLE_EXAMPLES=ON
cmake --build build
cd build/examples

Running functional tests

Download lunchtoast executable, build asyncgi examples and start NGINX with functional_tests/nginx_*.conf config file. Launch tests with the following command:

Linux command:

lunchtoast functional_tests

Windows command:

lunchtoast.exe functional_tests -shell="msys2 -c" -skip=linux

To run functional tests on Windows, it's recommended to use the bash shell from the msys2 project. After installing it, add the following script msys2.cmd to your system PATH:

@echo off
setlocal
IF NOT DEFINED MSYS2_PATH_TYPE set MSYS2_PATH_TYPE=inherit
set CHERE_INVOKING=1
C:\\msys64\\usr\\bin\\bash.exe -leo pipefail %*

License

asyncgi is licensed under the MS-PL license

Name		Name	Last commit message	Last commit date
Latest commit History 77 Commits
.github/workflows		.github/workflows
doc		doc
examples		examples
external		external
functional_tests		functional_tests
include/asyncgi		include/asyncgi
src		src
test_examples		test_examples
.clang-format		.clang-format
CMakeLists.txt		CMakeLists.txt
CMakePresets.json		CMakePresets.json
LICENSE.md		LICENSE.md
README.md		README.md
vcpkg.json		vcpkg.json

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