July 2017 - Boost - lists.preview.boost.org

[beast] Asynchronous examples
by Phil Endecott 03 Jul '17

03 Jul '17

Hi, Do any of the Beast examples show its use in asynchronous mode? I'm wondering how difficult it is to achieve this: future< vector< byte > > data = download(url); Regards, Phil.

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[beast] thread per connection example?
by Peter Dimov 02 Jul '17

02 Jul '17

Suppose that I want to implement an HTTP server that uses the thread per connection model. What example should I use as a starting point?

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[beast] Wy does message<> store Body::value_type?
by Peter Dimov 02 Jul '17

02 Jul '17

Why does message<isRequest, Body, Fields> store Body::value_type, using Body::reader and Body::writer to manipulate it, instead of the more straightforward approach of storing Body, which would have allowed making `get` and `put` members of the Body directly, instead of using intermediate classes?

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[beast] Automatic content-length?
by Peter Dimov 02 Jul '17

02 Jul '17

In this code, extracted from one of the examples in the documentation, // Set up the response, starting with the common fields response<string_body> res; res.version = 11; res.set(field::server, "test"); /*...*/ // We return responses indicating an error if // we do not recognize the request method. res.result(status::bad_request); res.set(field::content_type, "text/plain"); res.body = "Invalid request-method '" + req.method_string().to_string() + "'"; // Send the response write(stream, res, ec); field::content_length isn't set. Will Beast insert Content-Length based on the body size, or will it send the response with the field missing? The reason I ask is that I foresee forgetting the content_length to be a common mistake, and an asymptomatic one.

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[beast] socket versus stream
by Bjorn Reese 02 Jul '17

02 Jul '17

The HTTP API provides a set of free function for all operations, so all interaction follows this pattern: operation(socket, args); The WebSocket API wraps an Asio socket in a stream, so all operations are like this: stream.operation(args); I realize that the latter choice is a consequence of using SSL, but I am wondering why there is no socket.operation(args) style for the former?

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[gil::io] Dependent Name issue with VS2015 Update3
by Christian Henning 01 Jul '17

01 Jul '17

Hi all, using the new gil::io on gil's develop branch I get a compilation error with Visual Studio 2015 Update 3. When trying to read a tiff image: #include <string> #include <boost\gil\gil_all.hpp> #include <boost\gil\extension\io\tiff_all.hpp> using namespace std; using namespace boost::gil; int main() { rgba8_image_t img; read_image( string(), img, tiff_tag() ); return 0; } I get an error: error C2951: template declarations are only permitted at global, namespace, or class scope The problem seems to be with https://github.com/boostorg/gil/blob/develop/include/boost/gil/extension/io… Can someone please tell me if my issue is a compiler issue or simply a syntax error. Thanks, Christian

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Re: [boost] [Beast] Questions Before Review
by Artyom Beilis 01 Jul '17

01 Jul '17

http vs WebSocket -------------------------- I noticed some strange difference in these requests : // Wrap the now-connected socket in a websocket stream websocket::stream<tcp::socket&> ws{sock}; // Perform the websocket handhskae ws.handshake(host, "/", ec); if(ec) return fail("handshake", ec); This one is fast and easy to use does all it needed Now HTTP is very different story http::request<http::string_body> req; req.method(http::verb::get); req.target("/"); req.version = 11; req.set(http::field::host, host + ":" + std::to_string(sock.remote_endpoint().port())); req.set(http::field::user_agent, BEAST_VERSION_STRING); req.prepare_payload(); Most of stuff can be defined there by default: version 1.1, Host header - required by http/1.1 why should I bother? User agent put one by default unless user wants - you do all this stuff for WS handshake so why not there? Why so complicated? ----------------- Protocol Premier HTTP/1.1 example without host. Your example isn't valid HTTP /1.1 request. HTTP /1.1 unlike 1.0 requires host header Artyom

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[Beast] Security issue note
by Artyom Beilis 01 Jul '17

01 Jul '17

Looking into parser/body code I noticed: parser: void on_body(boost::optional< std::uint64_t> const& content_length, error_code& ec) { wr_.emplace(m_); wr_->init(content_length, ec); } string_body: void init(boost::optional< std::uint64_t> content_length, error_code& ec) { if(content_length) { if(*content_length > (std::numeric_limits< std::size_t>::max)()) { ec = make_error_code( errc::not_enough_memory); return; } ec.assign(0, ec.category()); body_.reserve(static_cast< std::size_t>(*content_length)); } } Basically I can exhaust the memory of the server and kill it by providing huge content length from several connections and lead to its crash. Reasonable and configurable limit should be provided for content length. Artyom Beilis

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[Beast] Questions Before Review
by Artyom Beilis 01 Jul '17

01 Jul '17

Hello Vinnie Falco, I have several design questions regarding this library before the review. DISCLIMER: My name is Artyom Beilis. I'm the author of CppCMS C++ Web Framework: http://cppcms.com It may seems like it can be in some competition with Beast but I don't see it this way as Beast is too low level library that does not addresses typical problems of developers needing Web API/Site running using C++. CppCMS addresses totally different problems in different way. So there are my design related questions: Header Only Design --------------------------- As somebody who worked with guys who do web development, it was very clear that compilation time is an issue. A simple build of http_server_small.cpp example requires about 6s(!) of compilation time g++ 5.4 http_server_fast.cpp takes 7s In comparison entire message board containing templates code flow SQL and more leads to only 4s - non paralel build. (https://github.com/artyom-beilis/cppcms/tree/master/examples/message_board ) I understand that you work on base of Boost.Asio - which itself has unacceptable compilation times but having for web application development may be serious deal breaker for big projects. Which Leads me to another design Choice Template Meta-programming Based Design instead of classic Object Oriented Design ---------------------------------------------------------------------------------------------------------------- I see that almost every object there is some kind of template object. It almost mimics the API of Boost.Asio which on its way has its limitations. I remember I needed to implement FastCGI over TCP and Unix domain sockets virtually leading to same code besides some initial bind - and it required to create the entire parser using template programming because the socket itself was template object different for UNIX and TCP. I have strong feeling that lots of stuff can actually be done using classic OOP. Example Question: > Can I implement same server code for both SSL and non SSL HTTP protocol > without use of templates in the class itself? And my current final question Who are the potential users of the library? ------------------------------------------------------- If I need to send a simple http request to server it does not seem to do simple enough job (see your FAQ) so I'll probably be better with feature rich libcurl. If I need to implement complex web server/service I don't have cookies, sessions, forms, html? If I need to implement RESTful API do I have all stuff like URL mapping of different paths to callbacks, protocol abstraction http/https (basic stuff - I don't see it there correct me if I wrong) Is it for web server developers? Maybe I'd be happier with simple HTTP protocol parser that I can integrate to any socket API? Can you please give more accurate description of who is this library intended for? Best Regards, Artyom Beilis

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Follow-up to the CMake follow-up
by Peter Dimov 01 Jul '17

01 Jul '17

Due to the strong interest in my previous follow-up, I'm following it up with a more complete implementation of the support required for CMake scenario #1, installing configuration files during "b2 install" such that subsequent "find_package" calls work (assuming a suitably set CMAKE_PREFIX_PATH). You can find it in branch "feature/install-cmake-config" in the superproject (boostorg/boost). In other words, git clone --recursive --depth 64 -b feature/install-cmake-config https://githib.com/boostorg/boost bootstrap b2 headers b2 install cmake//install variant=debug,release link=static,shared runtime-link=static,shared This doesn't yet support installation with more than one toolset, and I'm sure that some libraries don't work, but a simple test using Filesystem and ProgramOptions does. /// CMakeLists.txt: /// cmake_minimum_required(VERSION 3.5) project(cmake_demo CXX) list(APPEND CMAKE_PREFIX_PATH C:/Boost) find_package(boost_filesystem 1.63.0) find_package(boost_program_options 1.63.0) # disable autolink globally # could also do it per-target add_definitions(-DBOOST_ALL_NO_LIB=1) # sample program add_executable(cmake_demo cmake_demo.cpp) target_link_libraries(cmake_demo boost::filesystem boost::program_options) /// cmake_demo.cpp: /// #include <boost/filesystem.hpp> #include <boost/program_options.hpp> #include <cerrno> #include <iostream> namespace fs = boost::filesystem; namespace po = boost::program_options; int main( int argc, char const* argv[] ) { po::options_description desc( "Allowed options" ); desc.add_options() ( "help,h", "produce help message" ) ( "path,p", po::value<std::string>(), "set initial path" ) ; po::variables_map vm; try { po::store( po::parse_command_line( argc, argv, desc ), vm ); po::notify( vm ); } catch( std::exception const & x ) { std::cerr << "Error: " << x.what() << std::endl; return 1; } if( vm.count( "help" ) ) { std::cout << desc << std::endl; return 1; } fs::path p = fs::current_path(); if( vm.count( "path" ) ) { p = vm[ "path" ].as<std::string>(); } std::cout << p << std::endl; }

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