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Fwd: [beast] Trying to Integrate Chunked Encoding into server-sync Example
by Max D 29 May '24

29 May '24

Hi everyone, I'm trying to integrate the manual chunked encoding example [0] into the sync-server example [1] and have difficulties understanding a compiler error. I thought I might find some help in this mailing list. Here's my diff to the original example: @@ -151,6 +151,22 @@ handle_request( req.method() != http::verb::head) return send(bad_request("Unknown HTTP-method")); + if (req.target().find("/chunked") == 0) { + std::vector<uint8_t> data; + for (int i = 0; i < 10; i++) { + data.push_back(0x00); + } + net::const_buffer buf {data.data(), 10}; + + send.send_chunk_headers(); + + for (int i = 0; i < 3; i++) { + send.send_chunk(buf); + } + + send.send_last_chunk(); + } + // Request path must be absolute and not contain "..". if( req.target().empty() || req.target()[0] != '/' || @@ -243,6 +259,29 @@ struct send_lambda http::serializer<isRequest, Body, Fields> sr{msg}; http::write(stream_, sr, ec_); } + + void + send_chunk_headers() + { + http::response<http::empty_body> res {http::status::ok, 11}; + res.set(http::field::server, "Beast"); + res.chunked(true); + + http::response_serializer<http::empty_body> sr{res}; + http::write_header(stream_, sr); + } + + void + send_last_chunk() + { + http::write(stream_, http::make_chunk_last()); + } + + void + send_chunk(net::const_buffer buf) const + { + http::write(stream_, http::make_chunk(buf)); + } }; // Handles an HTTP server connection I'm passing a TCP socket as well as the result of http::make_chunk() with a net::const_buffer to http::write() which, if I understand correctly, is the same thing that is done in the example. However, I'm getting the following error when compiling: .../server-sync/src/beast.cpp: In instantiation of ‘void send_lambda<Stream>::send_chunk(boost::asio::const_buffer) const [with Stream = boost::asio::basic_stream_socket<boost::asio::ip::tcp>]’: .../server-sync/src/beast.cpp:164:28: required from ‘void handle_request(boost::beast::string_view, boost::beast::http::request<Body, boost::beast::http::basic_fields<Allocator> >&&, Send&&) [with B ody = boost::beast::http::basic_string_body<char>; Allocator = std::allocator<char>; Send = send_lambda<boost::asio::basic_stream_socket<boost::asio::ip::tcp> >&; boost::beast::string_view = boost::basic_string_view<char, std::char_traits< char> >; boost::beast::http::request<Body, boost::beast::http::basic_fields<Allocator> > = boost::beast::http::message<true, boost::beast::http::basic_string_body<char>, boost::beast::http::basic_fields<std::allocator<char> > >]’ .../server-sync/src/beast.cpp:313:57: required from here .../server-sync/src/beast.cpp:283:20: error: no matching function for call to ‘write(boost::asio::basic_stream_socket<boost::asio::ip::tcp>&, boost::beast::http::chunk_body<boost::asio::const_buffer>) ’ 283 | http::write(stream_, http::make_chunk(buf)); | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The same thing happens for the send_last_chunk() call. Why isn't the call to write() working? Did I misunderstand something in the example? I'm using boost 1.71 and am compiling with GCC 10.3.0. Let me know if you need any more details. Thanks in advance for any help Max --- [0] https://www.boost.org/doc/libs/1_71_0/libs/beast/doc/html/beast/using_http/… [1] https://www.boost.org/doc/libs/1_71_0/libs/beast/example/http/server/sync/h…

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boost::flyweights::intermodule_holder
by Foelsche, Peter 10 May '24

10 May '24

Dear All, Thanks for the boost library! Apparently the boost::flyweight::intermodule_holder on LINUX is creating shared memory objects, which by accident (crash?) can persist after the process having created them is already gone. As a result I ran into the following situation: I could not successfully run some code, as it attempted to create an already existing shared memory object created by another user. Would the following be a solution to this problem: Use a copy of the code of the static_holder inside another namespace as attached and compile one module with __INCLUDE_HOLDER__ defined and all the rest without this define? Peter

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Boost Graph - adjacency_list in_edge_iterator are only input_iterator_tag?
by Nic 10 May '24

10 May '24

Hi, Hopefully this is the right place for this. This with Boost 1.81.0 It looks like boost::adjacency_list's in_edge_iterator, out_edge_iterator, and for bidirectional graphs also edge_iterator all are only input iterators. This seems a bit restrictive, and is regardless of the type of EdgeList template parameter. For example, this code (which seems a relatively reasonable thing to want to do) doesn't work: https://godbolt.org/z/n3PdEYo49 It doesn't work because transform_view doesn't define iterator_category if the iterator is not at least a forward iterator (I'm a bit confused as to why that is, but that's not a boost-related thing). I did some digging and found out why the iterator is always an input iterator: The iterators are defined as following: template < class BaseIter, class VertexDescriptor, class EdgeDescriptor, class Difference > struct in_edge_iter : iterator_adaptor< in_edge_iter< BaseIter, VertexDescriptor, EdgeDescriptor, Difference >, BaseIter, EdgeDescriptor, use_default, EdgeDescriptor, Difference > { // .... }; EdgeDescriptor is passed in as the reference type, but it is not a reference so the iterator adaptor always chooses input_iterator_tag for the iterator_category. Does anyone know of a workaround, or know if this is the desired behavior for edge iterators? Am I missing something obvious here? Thank you very much, Nicolas Morales

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boost.asio: random_access_file, io_uring and thread safety
by Matwey V. Kornilov 30 Apr '24

30 Apr '24

Hello, random_access_file is backed by the io_uring kernel interface on Linux. However, It is still unclear from Boost.Asio documentation, whether simultaneous parallel async_write_at in-flight requests are permitted by Asio? The queue of simultaneous requests is natively supported by io_uring. Is it still true for Asio? Is it also safe to fire parallel async_write_at from different threads? -- With best regards, Matwey V. Kornilov

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Is there a buffered tcp stream in ASIO?
by accelerator0099 29 Apr '24

29 Apr '24

|Prepare a tcp server listening on [::]:23380, run the following code: #include <boost/asio.hpp> namespace io = boost::asio; using boost::system::system_error; int main() { try { io::io_context ctx; using io::ip::tcp; using io::buffer; tcp::socket s1(ctx); s1.connect(tcp::endpoint(io::ip::address_v4::loopback(), 23380)); for (size_t i{}; i != 10; ++i) io::write(s1, buffer("123", 3)); } catch (system_error& e) { return 1; } } strace says there are 10 syscalls: connect(6, {sa_family=AF_INET, sin_port=htons(23380), sin_addr=inet_addr("127.0.0.1")}, 16) = 0 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 If I use boost::asio::ip::tcp::iostream: #include <boost/asio.hpp> namespace io = boost::asio; using boost::system::system_error; int main() { try { io::io_context ctx; using io::ip::tcp; using io::buffer; tcp::iostream s1{ tcp::socket(ctx) }; auto& nl = s1.socket(); nl.connect(tcp::endpoint(io::ip::address_v4::loopback(), 23380)); for (size_t i{}; i != 10; ++i) s1.write("123", 3); s1.flush(); } catch (system_error& e) { return 1; } } It does not make sense, still 10 syscalls: connect(6, {sa_family=AF_INET, sin_port=htons(23380), sin_addr=inet_addr("127.0.0.1")}, 16) = 0 ioctl(6, FIONBIO, [1]) = 0 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 Is there a stream in asio that could buffer the multiple and small pieces of data into one syscall? |

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Difference in regex_replace replacement format handling between Boost.Regex and std::regex
by Josué Andrade Gomes 22 Apr '24

22 Apr '24

There is a difference in how the replacement format string is handled by regex_replace in Boost.Regex and std::regex. Consider the following example: #include <iostream>#include <regex>#include <boost/regex.hpp> int main() { std::string s{"a:b:c"}; std::string rx{":"}; std::string r{"\\$&"}; // Using std::regex std::string result_std = std::regex_replace(s, std::regex(rx), r); std::cout << "std::regex result: " << result_std << std::endl; // Outputs "a\:b\:c" // Using Boost.Regex std::string result_boost = boost::regex_replace(s, boost::regex(rx), r); std::cout << "Boost.Regex result: " << result_boost << std::endl; // Outputs "a$&b$&c" return 0; } std::regex result: a\:b\:c Boost.Regex result: a$&b$&c Affects Boost.Regex 1.84. I didn’t try other versions. Tested with GCC 13.2, clang 18.10 , cl 19.39.33523 and results are the same. Not tested with other versions. https://github.com/boostorg/regex/issues/210

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Regarding a Vulnerability in Boost.Regex library
by kamallochan Jena 18 Apr '24

18 Apr '24

Hello everyone, Hope you all are doing well. There is a Vulnerability reported on Boost library as mentioned below. Any guidance or assistance or reply to this mail would be greatly appreciated. *Vulnerability ID:* BDSA-2018-2656 *Vulnerability Details:* Boost has a flaw in the function boost::re_detail_NUMBER::basic_regex_creator which can lead to a buffer over-read. An attacker can craft and send a malicious file which will trigger the buffer over-read, leading to a denial-of-service. Few query w.r.t boost::re_detail_NUMBER::basic_regex_creator() function: 1. Does Boost.Regex library or any Boost library internally use this function? 2. If the answer is yes, Which all libraries use this function? 3. Is this a known vulnerability and is it fixed in the latest Boost version? please provide some insights like (any change list or file name etc). Our project uses a boost library(which has file "boost/regex/v4/basic_regex_creator.hpp") and uses Boost.Regex library functions. *Should we be worried about this vulnerability (BDSA-2018-2656) affecting our code? * Thanks!

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Any idea on CWE-704(BDSA-2018-1263) and CWE-126 (BDSA-2018-2656)
by kamallochan Jena 15 Apr '24

15 Apr '24

Dear all, Could someone assist me in determining if any version of Boost library is vulnerable to the following CWE? BDSA-2018-1263 CWE-704 and BDSA-2018-2656 CWE-126 Additionally, I would appreciate any details regarding these vulnerabilities, such as - the specific version of the Boost library where the vulnerability was identified - the name of the source code file, the exact line of code and function that causes the vulnerability - Whether the latest version of Boost includes a fix, and if so, which version of the library it was addressed in. Any guidance or assistance on this matter would be greatly appreciated. Thanks, Kjena

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Re: [Boost-users] [beast] I can't write a hello world server
by Senthil Cheetancheri 10 Apr '24

10 Apr '24

(Trying to repost because the previous message was rejected due to size limits.) Hi Loup, The reason I'm taking the time to ask here is because I feel there is something fundamental, likely obvious to the experts, that I don't understand about how beast (and, I'm guessing, asio) works, and how I'm supposed to use it. It seems like you are quite comfortable with C++. That is good because it is a necessary background for this. Boost.Asio and .Beast are inherently advanced topics. The examples use quite advanced C++ knowledge. It could appear simple to experts who understand asio and C++, as well as to newcomers if they were lucky to get the right orientation when they began to learn C++. I had to unlearn a lot of 'C' and old C++ notions. Here are some resources that helped me reach the Aha! moment after a lot of struggles. They are all well worth the patient time you will need. (They are from my bookmarks and are a bit dated. You can easily get the corresponding latest versions.) 1. ASIO: https://www.boost.org/doc/libs/1_79_0/doc/html/boost_asio.html 2. Beast: Watch this video https://youtu.be/7FQwAjELMek at the bottom of the tutorials page https://www.boost.org/doc/libs/1_80_0/libs/beast/doc/html/beast/examples.ht…. This video was a turning point for me. 3. If you would like interactive help, join the #beast channel of the cpplang slack https://cppalliance.org/slack/. They are very kind and super helpful. When you get asio and beast to work well, they are beautiful and give you joy. HTH. Thanks, Senthil.

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Boost.ASIO C++ 20 coroutine equivalent of PPL task_completion_event or JavaScript Promise.resolve?
by Willem Mitchell 09 Apr '24

09 Apr '24

I'm trying to write a simple ASIO send/receiver that uses message queueing. The goal is to have a number of virtual streams over a single TCP connection. This is pretty simple using callbacks, but I can't figure out the coroutines alternative. Here is my simplified sample code. Note that I'm using asio::experimental::promise the same way I would use std::promise which obviously doesn't work, but it illustrates what I'm trying to do. What is the simplest solution to my problem? #pragma once #include "asio.hpp" #include "asio/co_spawn.hpp" #include "asio/detached.hpp" #include "asio/experimental/co_composed.hpp" #include "asio/experimental/promise.hpp" #include "asio/use_awaitable.hpp" #include <coroutine> #include <cstdint> #include <map> #include <memory> #include <queue> struct Message { uint64_t id; uint64_t streamId; uint64_t priority; }; class NetworkConnection { public: NetworkConnection(asio::io_context &ioContext) : ioContext_(ioContext), sendTimer_(ioContext_), receiveTimer_(ioContext_){}; asio::awaitable<std::unique_ptr<Message>> receive(uint64_t streamId) { auto promise = std::make_shared< asio::experimental::promise<std::unique_ptr<Message>>>(); auto future = promise->get_future(); receives_[streamId] = promise; if (!receiving_) { receiving_ = true; co_spawn(ioContext_, startReceiving(), asio::detached); } co_return co_await future; } asio::awaitable<void> send(std::unique_ptr<Message> message) { auto promise = std::make_shared<asio::experimental::promise<void>>(); auto future = promise->get_future(); sends_[message->id] = promise; if (!sending_) { sending_ = true; co_spawn(ioContext_, startSending(), asio::detached); } co_await future; co_return; } private: asio::io_context &ioContext_; asio::steady_timer receiveTimer_; asio::steady_timer sendTimer_; std::map<uint64_t, std::shared_ptr< asio::experimental::promise<std::unique_ptr<Message>>>> receives_; std::map<uint64_t, std::shared_ptr<asio::experimental::promise<void>>> sends_; std::queue<std::unique_ptr<Message>> sendQueue_; bool receiving_ = false; bool sending_ = false; void completeSend(uint64_t messageId) { auto it = sends_.find(messageId); if (it != sends_.end()) { it->second->set_value(); // This resumes the send operation sends_.erase(it); // Clean up } } void completeReceive(std::unique_ptr<Message> message) { auto it = receives_.find(message->streamId); if (it != receives_.end()) { it->second->set_value( std::move(message)); // This resumes the send operation sends_.erase(it); // Clean up } } asio::awaitable<void> startReceiving() { while (!receives_.empty()) { // Simulate receiving a message sendTimer_.expires_after(std::chrono::seconds(1)); co_await sendTimer_.async_wait(asio::use_awaitable); auto message = std::make_unique<Message>(); message->id = 1; message->streamId = 1; message->priority = 1; completeReceive(std::move(message)); } receiving_ = false; co_return; } asio::awaitable<void> startSending() { while (!sends_.empty()) { sendTimer_.expires_after(std::chrono::seconds(1)); auto message = std::move(sendQueue_.front()); sendQueue_.pop(); co_await sendTimer_.async_wait(asio::use_awaitable); completeSend(message->id); } sending_ = false; co_return; } }; class Stream { public: Stream(std::shared_ptr<NetworkConnection> connection) : connection_(std::move(connection)) {} asio::awaitable<std::unique_ptr<Message>> receive() { co_return co_await connection_->receive(id_); } asio::awaitable<void> send(std::unique_ptr<Message> message) { message->streamId = id_; co_return co_await connection_->send(std::move(message)); } private: uint64_t id_; std::shared_ptr<NetworkConnection> connection_; };

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