# Crow: include/crow/websocket.h Source File

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websocket.h
#pragma once
#include <array>
#include "crow/logging.h"
#include "crow/socket_adaptors.h"
#include "crow/http_request.h"
#include "crow/TinySHA1.hpp"
#include "crow/utility.h"
namespace crow // NOTE: Already documented in "crow/app.h"
{
#ifdef CROW_USE_BOOST
namespace asio = boost::asio;
using error_code = boost::system::error_code;
#else
using error_code = asio::error_code;
#endif
/**
* \namespace crow::websocket
* \brief Namespace that includes the \ref Connection class
* and \ref connection struct. Useful for WebSockets connection.
*
* Used specially in crow/websocket.h, crow/app.h and crow/routing.h
*/
namespace websocket
{
enum class WebSocketReadState
{
MiniHeader,
Len16,
Len64,
Mask,
Payload,
};
/// A base class for websocket connection.
struct connection
{
virtual void send_binary(std::string msg) = 0;
virtual void send_text(std::string msg) = 0;
virtual void send_ping(std::string msg) = 0;
virtual void send_pong(std::string msg) = 0;
virtual void close(std::string const& msg = "quit") = 0;
virtual std::string get_remote_ip() = 0;
virtual ~connection() = default;
void userdata(void* u) { userdata_ = u; }
void* userdata() { return userdata_; }
private:
void* userdata_;
};
// Modified version of the illustration in RFC6455 Section-5.2
//
//
// 0 1 2 3 -byte
// 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 -bit
// +-+-+-+-+-------+-+-------------+-------------------------------+
// |F|R|R|R| opcode|M| Payload len | Extended payload length |
// |I|S|S|S| (4) |A| (7) | (16/64) |
// |N|V|V|V| |S| | (if payload len==126/127) |
// | |1|2|3| |K| | |
// +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
// | Extended payload length continued, if payload len == 127 |
// + - - - - - - - - - - - - - - - +-------------------------------+
// | |Masking-key, if MASK set to 1 |
// +-------------------------------+-------------------------------+
// | Masking-key (continued) | Payload Data |
// +-------------------------------- - - - - - - - - - - - - - - - +
// : Payload Data continued ... :
// + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
// | Payload Data continued ... |
// +---------------------------------------------------------------+
//
/// A websocket connection.
template<typename Adaptor, typename Handler>
class Connection : public connection
{
public:
/// Constructor for a connection.
///
/// Requires a request with an "Upgrade: websocket" header.<br>
/// Automatically handles the handshake.
Connection(const crow::request& req, Adaptor&& adaptor, Handler* handler, uint64_t max_payload,
std::function<void(crow::websocket::connection&)> open_handler,
std::function<void(crow::websocket::connection&, const std::string&, bool)> message_handler,
std::function<void(crow::websocket::connection&, const std::string&)> close_handler,
std::function<void(crow::websocket::connection&, const std::string&)> error_handler,
std::function<bool(const crow::request&, void**)> accept_handler):
adaptor_(std::move(adaptor)),
handler_(handler),
max_payload_bytes_(max_payload),
open_handler_(std::move(open_handler)),
message_handler_(std::move(message_handler)),
close_handler_(std::move(close_handler)),
error_handler_(std::move(error_handler)),
accept_handler_(std::move(accept_handler))
{
if (!utility::string_equals(req.get_header_value("upgrade"), "websocket"))
{
adaptor_.close();
handler_->remove_websocket(this);
delete this;
return;
}
if (accept_handler_)
{
void* ud = nullptr;
if (!accept_handler_(req, &ud))
{
adaptor_.close();
handler_->remove_websocket(this);
delete this;
return;
}
userdata(ud);
}
// Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
// Sec-WebSocket-Version: 13
std::string magic = req.get_header_value("Sec-WebSocket-Key") + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
sha1::SHA1 s;
s.processBytes(magic.data(), magic.size());
uint8_t digest[20];
s.getDigestBytes(digest);
start(crow::utility::base64encode((unsigned char*)digest, 20));
}
~Connection() noexcept override
{
// Do not modify anchor_ here since writing shared_ptr is not atomic.
auto watch = std::weak_ptr<void>{anchor_};
// Wait until all unhandled asynchronous operations to join.
// As the deletion occurs inside 'check_destroy()', which already locks
// anchor, use count can be 1 on valid deletion context.
while (watch.use_count() > 2) // 1 for 'check_destroy() routine', 1 for 'this->anchor_'
{
std::this_thread::yield();
}
}
template<typename Callable>
struct WeakWrappedMessage
{
Callable callable;
std::weak_ptr<void> watch;
void operator()()
{
if (auto anchor = watch.lock())
{
std::move(callable)();
}
}
};
/// Send data through the socket.
template<typename CompletionHandler>
void dispatch(CompletionHandler&& handler)
{
asio::dispatch(adaptor_.get_io_service(),
WeakWrappedMessage<typename std::decay<CompletionHandler>::type>{
std::forward<CompletionHandler>(handler), anchor_});
}
/// Send data through the socket and return immediately.
template<typename CompletionHandler>
void post(CompletionHandler&& handler)
{
asio::post(adaptor_.get_io_service(),
WeakWrappedMessage<typename std::decay<CompletionHandler>::type>{
std::forward<CompletionHandler>(handler), anchor_});
}
/// Send a "Ping" message.
///
/// Usually invoked to check if the other point is still online.
void send_ping(std::string msg) override
{
send_data(0x9, std::move(msg));
}
/// Send a "Pong" message.
///
/// Usually automatically invoked as a response to a "Ping" message.
void send_pong(std::string msg) override
{
send_data(0xA, std::move(msg));
}
/// Send a binary encoded message.
void send_binary(std::string msg) override
{
send_data(0x2, std::move(msg));
}
/// Send a plaintext message.
void send_text(std::string msg) override
{
send_data(0x1, std::move(msg));
}
/// Send a close signal.
///
/// Sets a flag to destroy the object once the message is sent.
void close(std::string const& msg) override
{
dispatch([this, msg]() mutable {
has_sent_close_ = true;
if (has_recv_close_ && !is_close_handler_called_)
{
is_close_handler_called_ = true;
if (close_handler_)
close_handler_(*this, msg);
}
auto header = build_header(0x8, msg.size());
write_buffers_.emplace_back(std::move(header));
write_buffers_.emplace_back(msg);
do_write();
});
}
std::string get_remote_ip() override
{
return adaptor_.remote_endpoint().address().to_string();
}
void set_max_payload_size(uint64_t payload)
{
max_payload_bytes_ = payload;
}
protected:
/// Generate the websocket headers using an opcode and the message size (in bytes).
std::string build_header(int opcode, size_t size)
{
char buf[2 + 8] = "\x80\x00";
buf[0] += opcode;
if (size < 126)
{
buf[1] += static_cast<char>(size);
return {buf, buf + 2};
}
else if (size < 0x10000)
{
buf[1] += 126;
*(uint16_t*)(buf + 2) = htons(static_cast<uint16_t>(size));
return {buf, buf + 4};
}
else
{
buf[1] += 127;
*reinterpret_cast<uint64_t*>(buf + 2) = ((1 == htonl(1)) ? static_cast<uint64_t>(size) : (static_cast<uint64_t>(htonl((size)&0xFFFFFFFF)) << 32) | htonl(static_cast<uint64_t>(size) >> 32));
return {buf, buf + 10};
}
}
/// Send the HTTP upgrade response.
///
/// Finishes the handshake process, then starts reading messages from the socket.
void start(std::string&& hello)
{
static const std::string header =
"HTTP/1.1 101 Switching Protocols\r\n"
"Upgrade: websocket\r\n"
"Connection: Upgrade\r\n"
"Sec-WebSocket-Accept: ";
write_buffers_.emplace_back(header);
write_buffers_.emplace_back(std::move(hello));
write_buffers_.emplace_back(crlf);
write_buffers_.emplace_back(crlf);
do_write();
if (open_handler_)
open_handler_(*this);
do_read();
}
/// Read a websocket message.
///
/// Involves:<br>
/// Handling headers (opcodes, size).<br>
/// Unmasking the payload.<br>
/// Reading the actual payload.<br>
void do_read()
{
if (has_sent_close_ && has_recv_close_)
{
close_connection_ = true;
adaptor_.shutdown_readwrite();
adaptor_.close();
check_destroy();
return;
}
is_reading = true;
switch (state_)
{
case WebSocketReadState::MiniHeader:
{
mini_header_ = 0;
//asio::async_read(adaptor_.socket(), asio::buffer(&mini_header_, 1),
adaptor_.socket().async_read_some(
asio::buffer(&mini_header_, 2),
[this](const error_code& ec, std::size_t
#ifdef CROW_ENABLE_DEBUG
bytes_transferred
#endif
)
{
is_reading = false;
mini_header_ = ntohs(mini_header_);
#ifdef CROW_ENABLE_DEBUG
if (!ec && bytes_transferred != 2)
{
throw std::runtime_error("WebSocket:MiniHeader:async_read fail:asio bug?");
}
#endif
if (!ec)
{
if ((mini_header_ & 0x80) == 0x80)
has_mask_ = true;
else //if the websocket specification is enforced and the message isn't masked, terminate the connection
{
#ifndef CROW_ENFORCE_WS_SPEC
has_mask_ = false;
#else
close_connection_ = true;
adaptor_.shutdown_readwrite();
adaptor_.close();
if (error_handler_)
error_handler_(*this, "Client connection not masked.");
check_destroy();
#endif
}
if ((mini_header_ & 0x7f) == 127)
{
state_ = WebSocketReadState::Len64;
}
else if ((mini_header_ & 0x7f) == 126)
{
state_ = WebSocketReadState::Len16;
}
else
{
remaining_length_ = mini_header_ & 0x7f;
state_ = WebSocketReadState::Mask;
}
do_read();
}
else
{
close_connection_ = true;
adaptor_.shutdown_readwrite();
adaptor_.close();
if (error_handler_)
error_handler_(*this, ec.message());
check_destroy();
}
});
}
break;
case WebSocketReadState::Len16:
{
remaining_length_ = 0;
remaining_length16_ = 0;
asio::async_read(
adaptor_.socket(), asio::buffer(&remaining_length16_, 2),
[this](const error_code& ec, std::size_t
#ifdef CROW_ENABLE_DEBUG
bytes_transferred
#endif
) {
is_reading = false;
remaining_length16_ = ntohs(remaining_length16_);
remaining_length_ = remaining_length16_;
#ifdef CROW_ENABLE_DEBUG
if (!ec && bytes_transferred != 2)
{
throw std::runtime_error("WebSocket:Len16:async_read fail:asio bug?");
}
#endif
if (!ec)
{
state_ = WebSocketReadState::Mask;
do_read();
}
else
{
close_connection_ = true;
adaptor_.shutdown_readwrite();
adaptor_.close();
if (error_handler_)
error_handler_(*this, ec.message());
check_destroy();
}
});
}
break;
case WebSocketReadState::Len64:
{
asio::async_read(
adaptor_.socket(), asio::buffer(&remaining_length_, 8),
[this](const error_code& ec, std::size_t
#ifdef CROW_ENABLE_DEBUG
bytes_transferred
#endif
) {
is_reading = false;
remaining_length_ = ((1 == ntohl(1)) ? (remaining_length_) : (static_cast<uint64_t>(ntohl((remaining_length_)&0xFFFFFFFF)) << 32) | ntohl((remaining_length_) >> 32));
#ifdef CROW_ENABLE_DEBUG
if (!ec && bytes_transferred != 8)
{
throw std::runtime_error("WebSocket:Len16:async_read fail:asio bug?");
}
#endif
if (!ec)
{
state_ = WebSocketReadState::Mask;
do_read();
}
else
{
close_connection_ = true;
adaptor_.shutdown_readwrite();
adaptor_.close();
if (error_handler_)
error_handler_(*this, ec.message());
check_destroy();
}
});
}
break;
case WebSocketReadState::Mask:
if (remaining_length_ > max_payload_bytes_)
{
close_connection_ = true;
adaptor_.close();
if (error_handler_)
error_handler_(*this, "Message length exceeds maximum payload.");
check_destroy();
}
else if (has_mask_)
{
asio::async_read(
adaptor_.socket(), asio::buffer((char*)&mask_, 4),
[this](const error_code& ec, std::size_t
#ifdef CROW_ENABLE_DEBUG
bytes_transferred
#endif
) {
is_reading = false;
#ifdef CROW_ENABLE_DEBUG
if (!ec && bytes_transferred != 4)
{
throw std::runtime_error("WebSocket:Mask:async_read fail:asio bug?");
}
#endif
if (!ec)
{
state_ = WebSocketReadState::Payload;
do_read();
}
else
{
close_connection_ = true;
if (error_handler_)
error_handler_(*this, ec.message());
adaptor_.shutdown_readwrite();
adaptor_.close();
check_destroy();
}
});
}
else
{
state_ = WebSocketReadState::Payload;
do_read();
}
break;
case WebSocketReadState::Payload:
{
auto to_read = static_cast<std::uint64_t>(buffer_.size());
if (remaining_length_ < to_read)
to_read = remaining_length_;
adaptor_.socket().async_read_some(
asio::buffer(buffer_, static_cast<std::size_t>(to_read)),
[this](const error_code& ec, std::size_t bytes_transferred) {
is_reading = false;
if (!ec)
{
fragment_.insert(fragment_.end(), buffer_.begin(), buffer_.begin() + bytes_transferred);
remaining_length_ -= bytes_transferred;
if (remaining_length_ == 0)
{
if (handle_fragment())
{
state_ = WebSocketReadState::MiniHeader;
do_read();
}
}
else
do_read();
}
else
{
close_connection_ = true;
if (error_handler_)
error_handler_(*this, ec.message());
adaptor_.shutdown_readwrite();
adaptor_.close();
check_destroy();
}
});
}
break;
}
}
/// Check if the FIN bit is set.
bool is_FIN()
{
return mini_header_ & 0x8000;
}
/// Extract the opcode from the header.
int opcode()
{
return (mini_header_ & 0x0f00) >> 8;
}
/// Process the payload fragment.
///
/// Unmasks the fragment, checks the opcode, merges fragments into 1 message body, and calls the appropriate handler.
bool handle_fragment()
{
if (has_mask_)
{
for (decltype(fragment_.length()) i = 0; i < fragment_.length(); i++)
{
fragment_[i] ^= ((char*)&mask_)[i % 4];
}
}
switch (opcode())
{
case 0: // Continuation
{
message_ += fragment_;
if (is_FIN())
{
if (message_handler_)
message_handler_(*this, message_, is_binary_);
message_.clear();
}
}
break;
case 1: // Text
{
is_binary_ = false;
message_ += fragment_;
if (is_FIN())
{
if (message_handler_)
message_handler_(*this, message_, is_binary_);
message_.clear();
}
}
break;
case 2: // Binary
{
is_binary_ = true;
message_ += fragment_;
if (is_FIN())
{
if (message_handler_)
message_handler_(*this, message_, is_binary_);
message_.clear();
}
}
break;
case 0x8: // Close
{
has_recv_close_ = true;
if (!has_sent_close_)
{
close(fragment_);
}
else
{
adaptor_.shutdown_readwrite();
adaptor_.close();
close_connection_ = true;
if (!is_close_handler_called_)
{
if (close_handler_)
close_handler_(*this, fragment_);
is_close_handler_called_ = true;
}
check_destroy();
return false;
}
}
break;
case 0x9: // Ping
{
send_pong(fragment_);
}
break;
case 0xA: // Pong
{
pong_received_ = true;
}
break;
}
fragment_.clear();
return true;
}
/// Send the buffers' data through the socket.
///
/// Also destroys the object if the Close flag is set.
void do_write()
{
if (sending_buffers_.empty())
{
sending_buffers_.swap(write_buffers_);
std::vector<asio::const_buffer> buffers;
buffers.reserve(sending_buffers_.size());
for (auto& s : sending_buffers_)
{
buffers.emplace_back(asio::buffer(s));
}
auto watch = std::weak_ptr<void>{anchor_};
asio::async_write(
adaptor_.socket(), buffers,
[&, watch](const error_code& ec, std::size_t /*bytes_transferred*/) {
if (!ec && !close_connection_)
{
sending_buffers_.clear();
if (!write_buffers_.empty())
do_write();
if (has_sent_close_)
close_connection_ = true;
}
else
{
auto anchor = watch.lock();
if (anchor == nullptr) { return; }
sending_buffers_.clear();
close_connection_ = true;
check_destroy();
}
});
}
}
/// Destroy the Connection.
void check_destroy()
{
//if (has_sent_close_ && has_recv_close_)
if (!is_close_handler_called_)
if (close_handler_)
close_handler_(*this, "uncleanly");
handler_->remove_websocket(this);
if (sending_buffers_.empty() && !is_reading)
delete this;
}
struct SendMessageType
{
std::string payload;
Connection* self;
int opcode;
void operator()()
{
self->send_data_impl(this);
}
};
void send_data_impl(SendMessageType* s)
{
auto header = build_header(s->opcode, s->payload.size());
write_buffers_.emplace_back(std::move(header));
write_buffers_.emplace_back(std::move(s->payload));
do_write();
}
void send_data(int opcode, std::string&& msg)
{
SendMessageType event_arg{
std::move(msg),
this,
opcode};
post(std::move(event_arg));
}
private:
Adaptor adaptor_;
Handler* handler_;
std::vector<std::string> sending_buffers_;
std::vector<std::string> write_buffers_;
std::array<char, 4096> buffer_;
bool is_binary_;
std::string message_;
std::string fragment_;
WebSocketReadState state_{WebSocketReadState::MiniHeader};
uint16_t remaining_length16_{0};
uint64_t remaining_length_{0};
uint64_t max_payload_bytes_{UINT64_MAX};
bool close_connection_{false};
bool is_reading{false};
bool has_mask_{false};
uint32_t mask_;
uint16_t mini_header_;
bool has_sent_close_{false};
bool has_recv_close_{false};
bool error_occurred_{false};
bool pong_received_{false};
bool is_close_handler_called_{false};
std::shared_ptr<void> anchor_ = std::make_shared<int>(); // Value is just for placeholding
std::function<void(crow::websocket::connection&)> open_handler_;
std::function<void(crow::websocket::connection&, const std::string&, bool)> message_handler_;
std::function<void(crow::websocket::connection&, const std::string&)> close_handler_;
std::function<void(crow::websocket::connection&, const std::string&)> error_handler_;
std::function<bool(const crow::request&, void**)> accept_handler_;
};
} // namespace websocket
} // namespace crow
TinySHA1.hpp
TinySHA1 - a header only implementation of the SHA1 algorithm in C++. Based on the implementation in ...
crow::websocket::Connection
A websocket connection.
Definition websocket.h:81
crow::websocket::Connection::dispatch
void dispatch(CompletionHandler &&handler)
Send data through the socket.
Definition websocket.h:166
crow::websocket::Connection::do_read
void do_read()
Read a websocket message.
Definition websocket.h:296
crow::websocket::Connection::send_pong
void send_pong(std::string msg) override
Send a "Pong" message.
Definition websocket.h:195
crow::websocket::Connection::handle_fragment
bool handle_fragment()
Process the payload fragment.
Definition websocket.h:555
crow::websocket::Connection::build_header
std::string build_header(int opcode, size_t size)
Generate the websocket headers using an opcode and the message size (in bytes).
Definition websocket.h:245
crow::websocket::Connection::send_text
void send_text(std::string msg) override
Send a plaintext message.
Definition websocket.h:207
crow::websocket::Connection::close
void close(std::string const &msg) override
Send a close signal.
Definition websocket.h:216
crow::websocket::Connection::opcode
int opcode()
Extract the opcode from the header.
Definition websocket.h:546
crow::websocket::Connection::do_write
void do_write()
Send the buffers' data through the socket.
Definition websocket.h:644
crow::websocket::Connection::check_destroy
void check_destroy()
Destroy the Connection.
Definition websocket.h:681
crow::websocket::Connection::start
void start(std::string &&hello)
Send the HTTP upgrade response.
Definition websocket.h:272
crow::websocket::Connection::is_FIN
bool is_FIN()
Check if the FIN bit is set.
Definition websocket.h:540
crow::websocket::Connection::send_ping
void send_ping(std::string msg) override
Send a "Ping" message.
Definition websocket.h:186
crow::websocket::Connection::send_binary
void send_binary(std::string msg) override
Send a binary encoded message.
Definition websocket.h:201
crow::websocket::Connection::Connection
Connection(const crow::request &req, Adaptor &&adaptor, Handler *handler, uint64_t max_payload, std::function< void(crow::websocket::connection &)> open_handler, std::function< void(crow::websocket::connection &, const std::string &, bool)> message_handler, std::function< void(crow::websocket::connection &, const std::string &)> close_handler, std::function< void(crow::websocket::connection &, const std::string &)> error_handler, std::function< bool(const crow::request &, void **)> accept_handler)
Constructor for a connection.
Definition websocket.h:88
crow::websocket::Connection::post
void post(CompletionHandler &&handler)
Send data through the socket and return immediately.
Definition websocket.h:175
sha1::SHA1
A tiny SHA1 algorithm implementation used internally in the Crow server (specifically in crow/websock...
Definition TinySHA1.hpp:48
crow
The main namespace of the library. In this namespace is defined the most important classes and functi...
crow::request
An HTTP request.
Definition http_request.h:36
crow::websocket::Connection::SendMessageType
Definition websocket.h:694
crow::websocket::Connection::WeakWrappedMessage
Definition websocket.h:151
crow::websocket::connection
A base class for websocket connection.
Definition websocket.h:38