Add async-ssl-system-executor http client example

This example websocket client application uses the `system_executor` to show
how to use it with the I/O objects in ASIO and Beast.

Signed-off-by: Damian Jarek <damian.jarek93@gmail.com>

example/websocket/client/CMakeLists.txt

@@ -13,6 +13,7 @@ add_subdirectory (sync)
 
 if (OPENSSL_FOUND)
     add_subdirectory (async-ssl)
+    add_subdirectory (async-ssl-system-executor)
     add_subdirectory (coro-ssl)
     add_subdirectory (sync-ssl)
 endif()

example/websocket/client/Jamfile

@@ -13,5 +13,6 @@ build-project sync ;
 
 # SSL
 build-project async-ssl ;
+build-project async-ssl-system-executor ;
 build-project coro-ssl ;
 build-project sync-ssl ;

example/websocket/client/async-ssl-system-executor/CMakeLists.txt

@@ -0,0 +1,31 @@
+#
+# Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/boostorg/beast
+#
+
+if (OPENSSL_FOUND)
+    GroupSources(include/boost/beast beast)
+    GroupSources(example/common common)
+    GroupSources(example/websocket/client/async-ssl "/")
+
+    add_executable (websocket-client-async-ssl-system-executor
+        ${BOOST_BEAST_FILES}
+        ${PROJECT_SOURCE_DIR}/example/common/root_certificates.hpp
+        Jamfile
+        websocket_client_async_ssl_system_executor.cpp
+    )
+
+    set_property(TARGET websocket-client-async-ssl-system-executor PROPERTY FOLDER "example-websocket-client-system-executor")
+
+    target_link_libraries (websocket-client-async-ssl-system-executor
+        OpenSSL::SSL OpenSSL::Crypto
+        lib-asio
+        lib-asio-ssl
+        lib-beast
+        )
+
+endif()

example/websocket/client/async-ssl-system-executor/Jamfile

@@ -0,0 +1,22 @@
+#
+# Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/boostorg/beast
+#
+
+import ac ;
+
+project
+    : requirements
+        [ ac.check-library /boost/beast//lib-asio-ssl : <library>/boost/beast//lib-asio-ssl/<link>static : <build>no ]
+    ;
+
+exe websocket-client-async-ssl-system-executor :
+    websocket_client_async_ssl_system_executor.cpp
+    :
+    <variant>coverage:<build>no
+    <variant>ubasan:<build>no
+    ;

example/websocket/client/async-ssl-system-executor/websocket_client_async_ssl_system_executor.cpp

@@ -0,0 +1,253 @@
+//
+// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+//------------------------------------------------------------------------------
+//
+// Example: WebSocket SSL client, asynchronous
+//
+//------------------------------------------------------------------------------
+
+#include "example/common/root_certificates.hpp"
+
+#include <boost/beast/core.hpp>
+#include <boost/beast/ssl.hpp>
+#include <boost/beast/websocket.hpp>
+#include <boost/beast/websocket/ssl.hpp>
+#include <boost/asio/strand.hpp>
+#include <cstdlib>
+#include <functional>
+#include <iostream>
+#include <memory>
+#include <string>
+
+namespace beast = boost::beast;         // from <boost/beast.hpp>
+namespace http = beast::http;           // from <boost/beast/http.hpp>
+namespace websocket = beast::websocket; // from <boost/beast/websocket.hpp>
+namespace net = boost::asio;            // from <boost/asio.hpp>
+namespace ssl = boost::asio::ssl;       // from <boost/asio/ssl.hpp>
+using tcp = boost::asio::ip::tcp;       // from <boost/asio/ip/tcp.hpp>
+
+//------------------------------------------------------------------------------
+
+// Report a failure
+void
+fail(beast::error_code ec, char const* what)
+{
+    std::cerr << what << ": " << ec.message() << "\n";
+}
+
+// Sends a WebSocket message and prints the response
+class session : public std::enable_shared_from_this<session>
+{
+    tcp::resolver resolver_;
+    websocket::stream<
+        beast::ssl_stream<beast::tcp_stream>> ws_;
+    beast::flat_buffer buffer_;
+    std::string host_;
+    std::string text_;
+
+    // Objects are constructed with a strand to
+    // ensure that handlers do not execute concurrently.
+    session(net::strand<net::system_executor> ex, ssl::context& ctx)
+        : resolver_(ex)
+        , ws_(ex, ctx)
+    {
+    }
+public:
+    // Delegate construction to a prive constructor to be able to use
+    // the same strand for both I/O objects.
+    explicit
+    session(ssl::context& ctx)
+        : session(net::make_strand(net::system_executor{}), ctx)
+    {
+    }
+
+    // Start the asynchronous operation
+    void
+    run(
+        char const* host,
+        char const* port,
+        char const* text)
+    {
+        // Save these for later
+        host_ = host;
+        text_ = text;
+
+        // Look up the domain name
+        resolver_.async_resolve(
+            host,
+            port,
+            beast::bind_front_handler(
+                &session::on_resolve,
+                shared_from_this()));
+    }
+
+    void
+    on_resolve(
+        beast::error_code ec,
+        tcp::resolver::results_type results)
+    {
+        if(ec)
+            return fail(ec, "resolve");
+
+        // Set a timeout on the operation
+        beast::get_lowest_layer(ws_).expires_after(std::chrono::seconds(30));
+
+        // Make the connection on the IP address we get from a lookup
+        beast::get_lowest_layer(ws_).async_connect(
+            results,
+            beast::bind_front_handler(
+                &session::on_connect,
+                shared_from_this()));
+    }
+
+    void
+    on_connect(beast::error_code ec, tcp::resolver::results_type::endpoint_type)
+    {
+        if(ec)
+            return fail(ec, "connect");
+
+        // Set a timeout on the operation
+        beast::get_lowest_layer(ws_).expires_after(std::chrono::seconds(30));
+
+        // Perform the SSL handshake
+        ws_.next_layer().async_handshake(
+            ssl::stream_base::client,
+            beast::bind_front_handler(
+                &session::on_ssl_handshake,
+                shared_from_this()));
+    }
+
+    void
+    on_ssl_handshake(beast::error_code ec)
+    {
+        if(ec)
+            return fail(ec, "ssl_handshake");
+
+        // Turn off the timeout on the tcp_stream, because
+        // the websocket stream has its own timeout system.
+        beast::get_lowest_layer(ws_).expires_never();
+
+        // Set suggested timeout settings for the websocket
+        ws_.set_option(
+            websocket::stream_base::timeout::suggested(
+                beast::role_type::client));
+
+        // Set a decorator to change the User-Agent of the handshake
+        ws_.set_option(websocket::stream_base::decorator(
+            [](websocket::request_type& req)
+            {
+                req.set(http::field::user_agent,
+                    std::string(BOOST_BEAST_VERSION_STRING) +
+                        " websocket-client-async-ssl");
+            }));
+
+        // Perform the websocket handshake
+        ws_.async_handshake(host_, "/",
+            beast::bind_front_handler(
+                &session::on_handshake,
+                shared_from_this()));
+    }
+
+    void
+    on_handshake(beast::error_code ec)
+    {
+        if(ec)
+            return fail(ec, "handshake");
+
+        // Send the message
+        ws_.async_write(
+            net::buffer(text_),
+            beast::bind_front_handler(
+                &session::on_write,
+                shared_from_this()));
+    }
+
+    void
+    on_write(
+        beast::error_code ec,
+        std::size_t bytes_transferred)
+    {
+        boost::ignore_unused(bytes_transferred);
+
+        if(ec)
+            return fail(ec, "write");
+
+        // Read a message into our buffer
+        ws_.async_read(
+            buffer_,
+            beast::bind_front_handler(
+                &session::on_read,
+                shared_from_this()));
+    }
+
+    void
+    on_read(
+        beast::error_code ec,
+        std::size_t bytes_transferred)
+    {
+        boost::ignore_unused(bytes_transferred);
+
+        if(ec)
+            return fail(ec, "read");
+
+        // Close the WebSocket connection
+        ws_.async_close(websocket::close_code::normal,
+            beast::bind_front_handler(
+                &session::on_close,
+                shared_from_this()));
+    }
+
+    void
+    on_close(beast::error_code ec)
+    {
+        if(ec)
+            return fail(ec, "close");
+
+        // If we get here then the connection is closed gracefully
+
+        // The make_printable() function helps print a ConstBufferSequence
+        std::cout << beast::make_printable(buffer_.data()) << std::endl;
+    }
+};
+
+//------------------------------------------------------------------------------
+
+int main(int argc, char** argv)
+{
+    // Check command line arguments.
+    if(argc != 4)
+    {
+        std::cerr <<
+            "Usage: websocket-client-async-ssl <host> <port> <text>\n" <<
+            "Example:\n" <<
+            "    websocket-client-async-ssl echo.websocket.org 443 \"Hello, world!\"\n";
+        return EXIT_FAILURE;
+    }
+    auto const host = argv[1];
+    auto const port = argv[2];
+    auto const text = argv[3];
+
+
+    // The SSL context is required, and holds certificates
+    ssl::context ctx{ssl::context::tlsv12_client};
+
+    // This holds the root certificate used for verification
+    load_root_certificates(ctx);
+
+    // Launch the asynchronous operation
+    std::make_shared<session>(ctx)->run(host, port, text);
+
+    // The async operations will run on the system_executor.
+    // Because the main thread has nothing to do in this example, we just wait
+    // for the system_executor to run out of work.
+    net::system_executor().context().join();
+
+    return EXIT_SUCCESS;
+}