Skip to content

Adds support for compressing websockets #329

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
fran6co wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Adds support for compressing websockets #329

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 3 additions & 0 deletions include/crow/settings.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,9 @@
/* #ifdef - enables ssl */
//#define CROW_ENABLE_SSL

/* #ifdef - enables websocket compression */
//#define CROW_ENABLE_WEBSOCKET_COMPRESSION

/* #define - specifies log level */
/*
Debug = 0
Expand Down
53 changes: 45 additions & 8 deletions include/crow/websocket.h
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,9 +1,11 @@
#pragma once
#include <boost/algorithm/string/predicate.hpp>
#include <boost/array.hpp>
#include <boost/algorithm/string/split.hpp>
#include "crow/socket_adaptors.h"
#include "crow/http_request.h"
#include "crow/TinySHA1.hpp"
#include "crow/zlib.hpp"

namespace crow
{
Expand Down Expand Up @@ -61,7 +63,18 @@ namespace crow
return;
}
}

#ifdef CROW_ENABLE_WEBSOCKET_COMPRESSION
std::string extensionsHeader = req.get_header_value("Sec-WebSocket-Extensions");
std::vector<std::string> extensions;
boost::split(extensions, extensionsHeader, boost::is_any_of(";"));
if (std::find(extensions.begin(), extensions.end(), "permessage-deflate") != extensions.end())
{
bool reset_compressor_on_send_ = std::find(extensions.begin(), extensions.end(), "server_no_context_takeover") != extensions.end();
compressor_.reset(new zlib_compressor(reset_compressor_on_send_, true, 15, Z_BEST_COMPRESSION, 8, Z_DEFAULT_STRATEGY));
bool reset_decompressor_on_send_ = std::find(extensions.begin(), extensions.end(), "client_no_context_takeover") != extensions.end();
decompressor_.reset(new zlib_decompressor(reset_decompressor_on_send_, true, 15));
}
#endif
// Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
// Sec-WebSocket-Version: 13
std::string magic = req.get_header_value("Sec-WebSocket-Key") + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
Expand Down Expand Up @@ -98,19 +111,23 @@ namespace crow
void send_binary(const std::string& msg) override
{
dispatch([this, msg]{
auto header = build_header(2, msg.size());
std::string msg_ = compressor_ ? compressor_->compress(msg) : msg;
auto header = build_header(2, msg_.size());
if (compressor_) header[0] += 0x40;
write_buffers_.emplace_back(std::move(header));
write_buffers_.emplace_back(msg);
write_buffers_.emplace_back(msg_);
do_write();
});
}

void send_text(const std::string& msg) override
{
dispatch([this, msg]{
auto header = build_header(1, msg.size());
std::string msg_ = compressor_ ? compressor_->compress(msg) : msg;
auto header = build_header(1, msg_.size());
if (compressor_) header[0] += 0x40;
write_buffers_.emplace_back(std::move(header));
write_buffers_.emplace_back(msg);
write_buffers_.emplace_back(msg_);
do_write();
});
}
Expand Down Expand Up @@ -167,6 +184,16 @@ namespace crow
write_buffers_.emplace_back(header);
write_buffers_.emplace_back(std::move(hello));
write_buffers_.emplace_back(crlf);
if (compressor_ && decompressor_) {
write_buffers_.emplace_back(
"Sec-WebSocket-Extensions: permessage-deflate"
"; server_max_window_bits=" + std::to_string(decompressor_->window_bits) +
"; client_max_window_bits=" + std::to_string(compressor_->window_bits) +
(compressor_->reset_before_compress ? "; server_no_context_takeover": "") +
(decompressor_->reset_before_decompress ? "; client_no_context_takeover": "")
);
write_buffers_.emplace_back(crlf);
}
write_buffers_.emplace_back(crlf);
do_write();
if (open_handler_)
Expand Down Expand Up @@ -368,6 +395,11 @@ namespace crow
return mini_header_ & 0x8000;
}

bool is_compressed()
{
return mini_header_ & 0x4000;
}

int opcode()
{
return (mini_header_ & 0x0f00) >> 8;
Expand All @@ -387,7 +419,7 @@ namespace crow
if (is_FIN())
{
if (message_handler_)
message_handler_(*this, message_, is_binary_);
message_handler_(*this, (is_compressed() && decompressor_) ? decompressor_->decompress(message_) : message_, is_binary_);
message_.clear();
}
}
Expand All @@ -398,7 +430,7 @@ namespace crow
if (is_FIN())
{
if (message_handler_)
message_handler_(*this, message_, is_binary_);
message_handler_(*this, (is_compressed() && decompressor_) ? decompressor_->decompress(message_) : message_, is_binary_);
message_.clear();
}
}
Expand All @@ -410,7 +442,7 @@ namespace crow
if (is_FIN())
{
if (message_handler_)
message_handler_(*this, message_, is_binary_);
message_handler_(*this, (is_compressed() && decompressor_) ? decompressor_->decompress(message_) : message_, is_binary_);
message_.clear();
}
}
Expand Down Expand Up @@ -514,6 +546,11 @@ namespace crow
bool pong_received_{false};
bool is_close_handler_called_{false};

bool reset_compressor_on_send_{false};
bool reset_decompressor_on_send_{false};
std::unique_ptr<zlib_compressor> compressor_;
std::unique_ptr<zlib_decompressor> decompressor_;

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_;
Expand Down
117 changes: 117 additions & 0 deletions include/crow/zlib.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,117 @@
#pragma once
#include "crow/settings.h"
#include <boost/asio/streambuf.hpp>
#include <zlib.h>
#include <string>

namespace crow {
class zlib_compressor {
public:
zlib_compressor(bool reset_before_compress, bool noheader, int window_bits, int level, int mem_level, int strategy)
: reset_before_compress(reset_before_compress)
, window_bits(window_bits) {
stream = std::make_unique<z_stream>();
stream->zalloc = 0;
stream->zfree = 0;
stream->opaque = 0;

::deflateInit2(stream.get(),
level,
Z_DEFLATED,
(noheader ? -window_bits : window_bits),
mem_level,
strategy
);
}

~zlib_compressor() {
::deflateEnd(stream.get());
}

std::string compress(const std::string& src) {
if(reset_before_compress)
::deflateReset(stream.get());

stream->next_in = reinterpret_cast<uint8_t*>(const_cast<char*>(src.c_str()));
stream->avail_in = src.size();

const uint64_t bufferSize = 256;
boost::asio::streambuf buffer;
do {
boost::asio::streambuf::mutable_buffers_type chunk = buffer.prepare(bufferSize);

uint8_t* next_out = boost::asio::buffer_cast<uint8_t*>(chunk);

stream->next_out = next_out;
stream->avail_out = bufferSize;

::deflate(stream.get(), reset_before_compress ? Z_FINISH : Z_SYNC_FLUSH);

uint64_t outputSize = stream->next_out - next_out;
buffer.commit(outputSize);
} while(stream->avail_out == 0);

uint64_t buffer_size = buffer.size();
if(!reset_before_compress) buffer_size -= 4;

return std::string(boost::asio::buffer_cast<const char*>(buffer.data()), buffer_size);
}

std::unique_ptr<z_stream> stream;

bool reset_before_compress;
int window_bits;
};

class zlib_decompressor {
public:
zlib_decompressor(bool reset_before_decompress, bool noheader, int window_bits)
: reset_before_decompress(reset_before_decompress)
, window_bits(window_bits) {
stream = std::make_unique<z_stream>();
stream->zalloc = 0;
stream->zfree = 0;
stream->opaque = 0;

::inflateInit2(stream.get(), (noheader ? -window_bits : window_bits));
}

~zlib_decompressor() {
inflateEnd(stream.get());
}

std::string decompress(std::string src) {
if(reset_before_decompress)
inflateReset(stream.get());

src.push_back('\x00');
src.push_back('\x00');
src.push_back('\xff');
src.push_back('\xff');

stream->next_in = reinterpret_cast<uint8_t*>(const_cast<char*>(src.c_str()));
stream->avail_in = src.size();

const uint64_t bufferSize = 256;
boost::asio::streambuf buffer;
do {
boost::asio::streambuf::mutable_buffers_type chunk = buffer.prepare(bufferSize);

uint8_t* next_out = boost::asio::buffer_cast<uint8_t*>(chunk);

stream->next_out = next_out;
stream->avail_out = bufferSize;

::inflate(stream.get(), reset_before_decompress ? Z_FINISH : Z_SYNC_FLUSH);
buffer.commit(stream->next_out - next_out);
} while(stream->avail_out == 0);

return std::string(boost::asio::buffer_cast<const char*>(buffer.data()), buffer.size());
}

std::unique_ptr<z_stream> stream;

bool reset_before_decompress;
int window_bits;
};
}