Function start

demo_example/http/coroutine_http/http_client.cpp:23–99

using asio::ip::tcp;

async_simple::coro::Lazy<void> start(asio::io_context &io_context,
                                     std::string host, std::string port) {
    asio::ip::tcp::socket socket(io_context);
    auto ec = co_await async_connect(io_context, socket, host, port);
    if (ec) {
        std::cout << "Connect error: " << ec.message() << '\n';
        throw asio::system_error(ec);
    }
    std::cout << "Connect to " << host << ":" << port << " successfully.\n";

    std::stringstream request_stream;
    request_stream << "GET "
                   << "/"
                   << " HTTP/1.1\r\n";
    request_stream << "Host: "
                   << "127.0.0.1"
                   << "\r\n";
    request_stream << "Accept: */*\r\n";
    request_stream << "Connection: close\r\n\r\n";

    // Send the request.
    co_await async_write(socket, asio::buffer(request_stream.str(),
                                              request_stream.str().size()));

    // Read the response status line. The response streambuf will automatically
    // grow to accommodate the entire line. The growth may be limited by passing
    // a maximum size to the streambuf constructor.
    asio::streambuf response;
    co_await async_read_until(socket, response, "\r\n");

    // Check that response is OK.
    std::istream response_stream(&response);
    std::string http_version;
    response_stream >> http_version;
    unsigned int status_code;
    response_stream >> status_code;
    std::string status_message;
    std::getline(response_stream, status_message);
    if (!response_stream || http_version.substr(0, 5) != "HTTP/") {
        std::cout << "Invalid response\n";
        co_return;
    }
    if (status_code != 200) {
        std::cout << "Response returned with status code " << status_code
                  << "\n";
        co_return;
    }

    // Read the response headers, which are terminated by a blank line.
    co_await async_read_until(socket, response, "\r\n\r\n");

    // Process the response headers.
    std::string header;
    while (std::getline(response_stream, header) && header != "\r")
        std::cout << header << "\n";
    std::cout << "\n";

    // Write whatever content we already have to output.