Add examples of Unix domain sockets

Closes #2918

example/websocket/client/async-local/websocket_client_async_local.cpp

@@ -0,0 +1,210 @@
+//
+// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
+// Copyright (c) 2025 Mohammad Nejati
+//
+// 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 client, asynchronous Unix domain sockets
+//
+//------------------------------------------------------------------------------
+
+#include <boost/asio/local/stream_protocol.hpp>
+#include <boost/asio/strand.hpp>
+#include <boost/beast/core.hpp>
+#include <boost/beast/websocket.hpp>
+
+#include <cstdlib>
+#include <iostream>
+#include <memory>
+#include <string>
+
+#if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+
+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>
+using stream_protocol = net::local::stream_protocol; // from <boost/asio/local/stream_protocol.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>
+{
+    websocket::stream<stream_protocol::socket> ws_;
+    beast::flat_buffer buffer_;
+    std::string host_;
+    std::string text_;
+
+public:
+    // Resolver and socket require an io_context
+    explicit
+    session(net::io_context& ioc)
+        : ws_(net::make_strand(ioc))
+    {
+    }
+
+    // Start the asynchronous operation
+    void
+    run(
+        char const* path,
+        char const* host,
+        char const* port,
+        char const* text)
+    {
+        // Save for later
+        host_ = std::string{host} + ":" + port;
+        text_ = text;
+
+        // Make the connection
+        beast::get_lowest_layer(ws_).async_connect(
+            stream_protocol::endpoint{path},
+            beast::bind_front_handler(
+                &session::on_connect,
+                shared_from_this()));
+    }
+
+    void
+    on_connect(beast::error_code ec)
+    {
+        if(ec)
+            return fail(ec, "connect");
+
+        // 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-local");
+            }));
+
+        // 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 != 5)
+    {
+        std::cerr <<
+            "Usage: websocket-client-async-local <path> <host> <port> <text>\n" <<
+            "Example:\n" <<
+            "    websocket-client-async-local /tmp/ws.sock localhost 80 \"Hello, world!\"\n";
+        return EXIT_FAILURE;
+    }
+    auto const path = argv[1];
+    auto const host = argv[2];
+    auto const port = argv[3];
+    auto const text = argv[4];
+
+    // The io_context is required for all I/O
+    net::io_context ioc;
+
+    // Launch the asynchronous operation
+    std::make_shared<session>(ioc)->run(path, host, port, text);
+
+    // Run the I/O service. The call will return when
+    // the socket is closed.
+    ioc.run();
+
+    return EXIT_SUCCESS;
+}
+
+#else
+
+int
+main(int, char*[])
+{
+std::cerr <<
+    "Local sockets not available on this platform" << std::endl;
+return EXIT_FAILURE;
+}
+
+#endif