boost_beast/include/beast/websocket/impl/stream.ipp

//
// Copyright (c) 2013-2016 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BEAST_WEBSOCKET_IMPL_STREAM_IPP
#define BEAST_WEBSOCKET_IMPL_STREAM_IPP

#include <beast/websocket/teardown.hpp>
#include <beast/websocket/detail/hybi13.hpp>
#include <beast/websocket/impl/accept_op.ipp>
#include <beast/websocket/impl/close_op.ipp>
#include <beast/websocket/impl/handshake_op.ipp>
#include <beast/websocket/impl/read_op.ipp>
#include <beast/websocket/impl/read_frame_op.ipp>
#include <beast/websocket/impl/response_op.ipp>
#include <beast/websocket/impl/write_op.ipp>
#include <beast/websocket/impl/write_frame_op.ipp>
#include <beast/http/read.hpp>
#include <beast/http/write.hpp>
#include <beast/http/reason.hpp>
#include <beast/http/rfc2616.hpp>
#include <beast/buffer_cat.hpp>
#include <beast/buffer_concepts.hpp>
#include <beast/consuming_buffers.hpp>
#include <beast/prepare_buffers.hpp>
#include <beast/static_streambuf.hpp>
#include <beast/stream_concepts.hpp>
#include <beast/streambuf.hpp>
#include <boost/endian/buffers.hpp>
#include <algorithm>
#include <cassert>
#include <memory>
#include <utility>

namespace beast {
namespace websocket {

namespace detail {

template<class _>
void
stream_base::prepare_fh(close_code::value& code)
{
    // continuation without an active message
    if(! rd_cont_ && rd_fh_.op == opcode::cont)
    {
        code = close_code::protocol_error;
        return;
    }
    // new data frame when continuation expected
    if(rd_cont_ && ! is_control(rd_fh_.op) &&
        rd_fh_.op != opcode::cont)
    {
        code = close_code::protocol_error;
        return;
    }
    if(rd_fh_.mask)
        prepare_key(rd_key_, rd_fh_.key);
    if(! is_control(rd_fh_.op))
    {
        if(rd_fh_.op != opcode::cont)
        {
            rd_size_ = rd_fh_.len;
            rd_opcode_ = rd_fh_.op;
        }
        else
        {
            if(rd_size_ > std::numeric_limits<
                std::uint64_t>::max() - rd_fh_.len)
            {
                code = close_code::too_big;
                return;
            }
            rd_size_ += rd_fh_.len;
        }
        if(rd_size_ > rd_msg_max_)
        {
            code = close_code::too_big;
            return;
        }
        rd_need_ = rd_fh_.len;
        rd_cont_ = ! rd_fh_.fin;
    }
}

template<class Streambuf>
void
stream_base::write_close(
    Streambuf& sb, close_reason const& cr)
{
    using namespace boost::endian;
    frame_header fh;
    fh.op = opcode::close;
    fh.fin = true;
    fh.rsv1 = false;
    fh.rsv2 = false;
    fh.rsv3 = false;
    fh.len = cr.code == close_code::none ?
        0 : 2 + cr.reason.size();
    fh.mask = role_ == role_type::client;
    if(fh.mask)
        fh.key = maskgen_();
    detail::write(sb, fh);
    if(cr.code != close_code::none)
    {
        detail::prepared_key_type key;
        if(fh.mask)
            detail::prepare_key(key, fh.key);
        {
            std::uint8_t b[2];
            ::new(&b[0]) big_uint16_buf_t{
                (std::uint16_t)cr.code};
            auto d = sb.prepare(2);
            boost::asio::buffer_copy(d,
                boost::asio::buffer(b));
            if(fh.mask)
                detail::mask_inplace(d, key);
            sb.commit(2);
        }
        if(! cr.reason.empty())
        {
            auto d = sb.prepare(cr.reason.size());
            boost::asio::buffer_copy(d,
                boost::asio::const_buffer(
                    cr.reason.data(), cr.reason.size()));
            if(fh.mask)
                detail::mask_inplace(d, key);
            sb.commit(cr.reason.size());
        }
    }
}

template<class Streambuf>
void
stream_base::write_ping(Streambuf& sb,
    opcode op, ping_payload_type const& data)
{
    frame_header fh;
    fh.op = op;
    fh.fin = true;
    fh.rsv1 = false;
    fh.rsv2 = false;
    fh.rsv3 = false;
    fh.len = data.size();
    fh.mask = role_ == role_type::client;
    if(fh.mask)
        fh.key = maskgen_();
    detail::write(sb, fh);
    if(data.empty())
        return;
    detail::prepared_key_type key;
    if(fh.mask)
        detail::prepare_key(key, fh.key);
    auto d = sb.prepare(data.size());
    boost::asio::buffer_copy(d,
        boost::asio::const_buffers_1(
            data.data(), data.size()));
    if(fh.mask)
        detail::mask_inplace(d, key);
    sb.commit(data.size());
}

} // detail

//------------------------------------------------------------------------------

template<class NextLayer>
template<class... Args>
stream<NextLayer>::
stream(Args&&... args)
    : stream_(std::forward<Args>(args)...)
{
}

template<class NextLayer>
void
stream<NextLayer>::
accept()
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    accept(boost::asio::null_buffers{}, ec);
    detail::maybe_throw(ec, "accept");
}

template<class NextLayer>
void
stream<NextLayer>::
accept(error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    accept(boost::asio::null_buffers{}, ec);
}

template<class NextLayer>
template<class AcceptHandler>
typename async_completion<
    AcceptHandler, void(error_code)>::result_type
stream<NextLayer>::
async_accept(AcceptHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements requirements not met");
    return async_accept(boost::asio::null_buffers{},
        std::forward<AcceptHandler>(handler));
}

template<class NextLayer>
template<class ConstBufferSequence>
void
stream<NextLayer>::
accept(ConstBufferSequence const& buffers)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    static_assert(is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    error_code ec;
    accept(buffers, ec);
    detail::maybe_throw(ec, "accept");
}

template<class NextLayer>
template<class ConstBufferSequence>
void
stream<NextLayer>::
accept(ConstBufferSequence const& buffers, error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    static_assert(beast::is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    using boost::asio::buffer_copy;
    using boost::asio::buffer_size;
    stream_.buffer().commit(buffer_copy(
        stream_.buffer().prepare(
            buffer_size(buffers)), buffers));
    http::request_v1<http::empty_body> m;
    http::read(next_layer(), stream_.buffer(), m, ec);
    if(ec)
        return;
    accept(m, ec);
}

template<class NextLayer>
template<class ConstBufferSequence, class AcceptHandler>
typename async_completion<
    AcceptHandler, void(error_code)>::result_type
stream<NextLayer>::
async_accept(ConstBufferSequence const& bs, AcceptHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements requirements not met");
    static_assert(beast::is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    beast::async_completion<
        AcceptHandler, void(error_code)
            > completion(handler);
    accept_op<decltype(completion.handler)>{
        completion.handler, *this, bs};
    return completion.result.get();
}

template<class NextLayer>
template<class Body, class Headers>
void
stream<NextLayer>::
accept(http::request_v1<Body, Headers> const& request)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    accept(request, ec);
    detail::maybe_throw(ec, "accept");
}

template<class NextLayer>
template<class Body, class Headers>
void
stream<NextLayer>::
accept(http::request_v1<Body, Headers> const& req,
    error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    auto const resp = build_response(req);
    http::write(stream_, resp, ec);
    if(resp.status != 101)
    {
        ec = error::handshake_failed;
        // VFALCO TODO Respect keep alive setting, perform
        //             teardown if Connection: close.
        return;
    }
    role_ = role_type::server;
}

template<class NextLayer>
template<class Body, class Headers, class AcceptHandler>
typename async_completion<
    AcceptHandler, void(error_code)>::result_type
stream<NextLayer>::
async_accept(http::request_v1<Body, Headers> const& req,
    AcceptHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements requirements not met");
    beast::async_completion<
        AcceptHandler, void(error_code)
            > completion(handler);
    response_op<decltype(completion.handler)>{
        completion.handler, *this, req,
            boost_asio_handler_cont_helpers::
                is_continuation(completion.handler)};
    return completion.result.get();
}

template<class NextLayer>
void
stream<NextLayer>::
handshake(boost::string_ref const& host,
    boost::string_ref const& resource)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    handshake(host, resource, ec);
    detail::maybe_throw(ec, "upgrade");
}

template<class NextLayer>
void
stream<NextLayer>::
handshake(boost::string_ref const& host,
    boost::string_ref const& resource, error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    std::string key;
    http::write(stream_,
        build_request(host, resource, key), ec);
    if(ec)
        return;
    http::response_v1<http::string_body> resp;
    http::read(next_layer(), stream_.buffer(), resp, ec);
    if(ec)
        return;
    do_response(resp, key, ec);
}

template<class NextLayer>
template<class HandshakeHandler>
typename async_completion<
    HandshakeHandler, void(error_code)>::result_type
stream<NextLayer>::
async_handshake(boost::string_ref const& host,
    boost::string_ref const& resource, HandshakeHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements not met");
    beast::async_completion<
        HandshakeHandler, void(error_code)
            > completion(handler);
    handshake_op<decltype(completion.handler)>{
        completion.handler, *this, host, resource};
    return completion.result.get();
}

template<class NextLayer>
void
stream<NextLayer>::
close(close_reason const& cr)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    close(cr, ec);
    detail::maybe_throw(ec, "close");
}

template<class NextLayer>
void
stream<NextLayer>::
close(close_reason const& cr, error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    assert(! wr_close_);
    wr_close_ = true;
    detail::frame_streambuf fb;
    write_close<static_streambuf>(fb, cr);
    boost::asio::write(stream_, fb.data(), ec);
    error_ = ec != 0;
}

template<class NextLayer>
template<class CloseHandler>
typename async_completion<
    CloseHandler, void(error_code)>::result_type
stream<NextLayer>::
async_close(close_reason const& cr, CloseHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements not met");
    beast::async_completion<
        CloseHandler, void(error_code)
            > completion(handler);
    close_op<decltype(completion.handler)>{
        completion.handler, *this, cr};
    return completion.result.get();
}

template<class NextLayer>
template<class Streambuf>
void
stream<NextLayer>::
read(opcode& op, Streambuf& streambuf)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    read(op, streambuf, ec);
    detail::maybe_throw(ec, "read");
}

template<class NextLayer>
template<class Streambuf>
void
stream<NextLayer>::
read(opcode& op, Streambuf& streambuf, error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    frame_info fi;
    for(;;)
    {
        read_frame(fi, streambuf, ec);
        if(ec)
            break;
        op = fi.op;
        if(fi.fin)
            break;
    }
}

template<class NextLayer>
template<class Streambuf, class ReadHandler>
typename async_completion<
    ReadHandler, void(error_code)>::result_type
stream<NextLayer>::
async_read(opcode& op,
    Streambuf& streambuf, ReadHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements requirements not met");
    static_assert(beast::is_Streambuf<Streambuf>::value,
        "Streambuf requirements not met");
    beast::async_completion<
        ReadHandler, void(error_code)
            > completion(handler);
    read_op<Streambuf, decltype(completion.handler)>{
        completion.handler, *this, op, streambuf};
    return completion.result.get();
}

template<class NextLayer>
template<class Streambuf>
void
stream<NextLayer>::
read_frame(frame_info& fi, Streambuf& streambuf)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    read_frame(fi, streambuf, ec);
    detail::maybe_throw(ec, "read_some");
}

template<class NextLayer>
template<class Streambuf>
void
stream<NextLayer>::
read_frame(frame_info& fi, Streambuf& streambuf, error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    close_code::value code{};
    for(;;)
    {
        if(rd_need_ == 0)
        {
            // read header
            detail::frame_streambuf fb;
            do_read_fh(fb, code, ec);
            error_ = ec != 0;
            if(error_)
                return;
            if(code != close_code::none)
                break;
            if(detail::is_control(rd_fh_.op))
            {
                // read control payload
                if(rd_fh_.len > 0)
                {
                    auto const mb = fb.prepare(
                        static_cast<std::size_t>(rd_fh_.len));
                    fb.commit(boost::asio::read(stream_, mb, ec));
                    error_ = ec != 0;
                    if(error_)
                        return;
                    if(rd_fh_.mask)
                        detail::mask_inplace(mb, rd_key_);
                    fb.commit(static_cast<std::size_t>(rd_fh_.len));
                }
                if(rd_fh_.op == opcode::ping)
                {
                    ping_payload_type data;
                    detail::read(data, fb.data(), code);
                    if(code != close_code::none)
                        break;
                    fb.reset();
                    write_ping<static_streambuf>(
                        fb, opcode::pong, data);
                    boost::asio::write(stream_, fb.data(), ec);
                    error_ = ec != 0;
                    if(error_)
                        return;
                    continue;
                }
                else if(rd_fh_.op == opcode::pong)
                {
                    ping_payload_type data;
                    detail::read(data, fb.data(), code);
                    if(code != close_code::none)
                        break;
                    // VFALCO How to notify callers using
                    //        the synchronous interface?
                    continue;
                }
                assert(rd_fh_.op == opcode::close);
                {
                    detail::read(cr_, fb.data(), code);
                    if(code != close_code::none)
                        break;
                    if(! wr_close_)
                    {
                        auto cr = cr_;
                        if(cr.code == close_code::none)
                            cr.code = close_code::normal;
                        cr.reason = "";
                        fb.reset();
                        wr_close_ = true;
                        write_close<static_streambuf>(fb, cr);
                        boost::asio::write(stream_, fb.data(), ec);
                        error_ = ec != 0;
                        if(error_)
                            return;
                    }
                    break;
                }
            }
            if(rd_need_ == 0 && ! rd_fh_.fin)
            {
                // empty frame
                continue;
            }
        }
        // read payload
        auto smb = streambuf.prepare(
            detail::clamp(rd_need_));
        auto const bytes_transferred =
            stream_.read_some(smb, ec);
        error_ = ec != 0;
        if(error_)
            return;
        rd_need_ -= bytes_transferred;
        auto const pb = prepare_buffers(
            bytes_transferred, smb);
        if(rd_fh_.mask)
            detail::mask_inplace(pb, rd_key_);
        if(rd_opcode_ == opcode::text)
        {
            if(! rd_utf8_check_.write(pb) ||
                (rd_need_ == 0 && rd_fh_.fin &&
                    ! rd_utf8_check_.finish()))
            {
                code = close_code::bad_payload;
                break;
            }
        }
        streambuf.commit(bytes_transferred);
        fi.op = rd_opcode_;
        fi.fin = rd_fh_.fin && rd_need_ == 0;
        return;
    }
    if(code != close_code::none)
    {
        // Fail the connection (per rfc6455)
        if(! wr_close_)
        {
            wr_close_ = true;
            detail::frame_streambuf fb;
            write_close<static_streambuf>(fb, code);
            boost::asio::write(stream_, fb.data(), ec);
            error_ = ec != 0;
            if(error_)
                return;
        }
        websocket_helpers::call_teardown(next_layer(), ec);
        error_ = ec != 0;
        if(error_)
            return;
        ec = error::failed;
        error_ = true;
        return;
    }
    if(! ec)
        websocket_helpers::call_teardown(next_layer(), ec);
    if(! ec)
        ec = error::closed;
    error_ = ec != 0;
}

template<class NextLayer>
template<class Streambuf, class ReadHandler>
typename async_completion<
    ReadHandler, void(error_code)>::result_type
stream<NextLayer>::
async_read_frame(frame_info& fi,
    Streambuf& streambuf, ReadHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements requirements not met");
    static_assert(beast::is_Streambuf<Streambuf>::value,
        "Streambuf requirements not met");
    beast::async_completion<
        ReadHandler, void(error_code)> completion(handler);
    read_frame_op<Streambuf, decltype(completion.handler)>{
        completion.handler, *this, fi, streambuf};
    return completion.result.get();
}

template<class NextLayer>
template<class ConstBufferSequence>
void
stream<NextLayer>::
write(ConstBufferSequence const& buffers)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    write(buffers, ec);
    detail::maybe_throw(ec, "write");
}

template<class NextLayer>
template<class ConstBufferSequence>
void
stream<NextLayer>::
write(ConstBufferSequence const& bs, error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    static_assert(beast::is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    using boost::asio::buffer_size;
    consuming_buffers<ConstBufferSequence> cb(bs);
    auto remain = buffer_size(cb);
    for(;;)
    {
        auto const n =
            detail::clamp(remain, wr_frag_size_);
        remain -= n;
        auto const fin = remain <= 0;
        write_frame(fin, prepare_buffers(n, cb), ec);
        cb.consume(n);
        if(ec)
            return;
        if(fin)
            break;
    }
}

template<class NextLayer>
template<class ConstBufferSequence, class WriteHandler>
typename async_completion<
    WriteHandler, void(error_code)>::result_type
stream<NextLayer>::
async_write(ConstBufferSequence const& bs, WriteHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements not met");
    static_assert(beast::is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    beast::async_completion<
        WriteHandler, void(error_code)> completion(handler);
    write_op<ConstBufferSequence, decltype(completion.handler)>{
        completion.handler, *this, bs};
    return completion.result.get();
}

template<class NextLayer>
template<class ConstBufferSequence>
void
stream<NextLayer>::
write_frame(bool fin, ConstBufferSequence const& buffers)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    write_frame(fin, buffers, ec);
    detail::maybe_throw(ec, "write");
}

template<class NextLayer>
template<class ConstBufferSequence>
void
stream<NextLayer>::
write_frame(bool fin, ConstBufferSequence const& bs, error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    static_assert(beast::is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    using boost::asio::buffer_copy;
    using boost::asio::buffer_size;
    using boost::asio::mutable_buffers_1;
    detail::frame_header fh;
    fh.op = wr_cont_ ? opcode::cont : wr_opcode_;
    wr_cont_ = ! fin;
    fh.fin = fin;
    fh.rsv1 = false;
    fh.rsv2 = false;
    fh.rsv3 = false;
    fh.len = buffer_size(bs);
    fh.mask = role_ == role_type::client;
    if(fh.mask)
        fh.key = maskgen_();
    detail::fh_streambuf fh_buf;
    detail::write<static_streambuf>(fh_buf, fh);
    if(! fh.mask)
    {
        // send header and payload
        boost::asio::write(stream_,
            buffer_cat(fh_buf.data(), bs), ec);
        error_ = ec != 0;
        return;
    }
    detail::prepared_key_type key;
    detail::prepare_key(key, fh.key);
    auto const tmp_size = detail::clamp(
        fh.len, wr_buf_size_);
    std::unique_ptr<std::uint8_t[]> up(
        new std::uint8_t[tmp_size]);
    auto const tmp = up.get();
    std::uint64_t remain = fh.len;
    consuming_buffers<ConstBufferSequence> cb(bs);
    {
        auto const n =
            detail::clamp(remain, tmp_size);
        mutable_buffers_1 mb{tmp, n};
        buffer_copy(mb, cb);
        cb.consume(n);
        remain -= n;
        detail::mask_inplace(mb, key);
        // send header and payload
        boost::asio::write(stream_,
            buffer_cat(fh_buf.data(), mb), ec);
        if(ec)
        {
            error_ = ec != 0;
            return;
        }
    }
    while(remain > 0)
    {
        auto const n =
            detail::clamp(remain, tmp_size);
        mutable_buffers_1 mb{tmp, n};
        buffer_copy(mb, cb);
        cb.consume(n);
        remain -= n;
        detail::mask_inplace(mb, key);
        // send payload
        boost::asio::write(stream_, mb, ec);
        if(ec)
        {
            error_ = ec != 0;
            return;
        }
    }
}

template<class NextLayer>
template<class ConstBufferSequence, class WriteHandler>
typename async_completion<
    WriteHandler, void(error_code)>::result_type
stream<NextLayer>::
async_write_frame(bool fin,
    ConstBufferSequence const& bs, WriteHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements not met");
    static_assert(beast::is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    beast::async_completion<
        WriteHandler, void(error_code)
            > completion(handler);
    write_frame_op<ConstBufferSequence, decltype(
        completion.handler)>{completion.handler,
            *this, fin, bs};
    return completion.result.get();
}

//------------------------------------------------------------------------------

template<class NextLayer>
http::request_v1<http::empty_body>
stream<NextLayer>::
build_request(boost::string_ref const& host,
    boost::string_ref const& resource, std::string& key)
{
    http::request_v1<http::empty_body> req;
    req.url = "/";
    req.version = 11;
    req.method = "GET";
    req.headers.insert("Host", host);
    req.headers.insert("Upgrade", "websocket");
    key = detail::make_sec_ws_key(maskgen_);
    req.headers.insert("Sec-WebSocket-Key", key);
    req.headers.insert("Sec-WebSocket-Version", "13");
    (*d_)(req);
    http::prepare(req, http::connection::upgrade);
    return req;
}

template<class NextLayer>
template<class Body, class Headers>
http::response_v1<http::string_body>
stream<NextLayer>::
build_response(http::request_v1<Body, Headers> const& req)
{
    auto err =
        [&](std::string const& text)
        {
            http::response_v1<http::string_body> resp(
                {400, http::reason_string(400), req.version});
            resp.body = text;
            // VFALCO TODO respect keep-alive here
            return resp;
        };
    if(req.version < 11)
        return err("HTTP version 1.1 required");
    if(req.method != "GET")
        return err("Wrong method");
    if(! is_upgrade(req))
        return err("Expected Upgrade request");
    if(! req.headers.exists("Host"))
        return err("Missing Host");
    if(! req.headers.exists("Sec-WebSocket-Key"))
        return err("Missing Sec-WebSocket-Key");
    {
        auto const version =
            req.headers["Sec-WebSocket-Version"];
        if(version.empty())
            return err("Missing Sec-WebSocket-Version");
        if(version != "13")
            return err("Unsupported Sec-WebSocket-Version");
    }
    if(! rfc2616::token_in_list(
            req.headers["Upgrade"], "websocket"))
        return err("Missing websocket Upgrade token");
    http::response_v1<http::string_body> resp(
        {101, http::reason_string(101), req.version});
    resp.headers.insert("Upgrade", "websocket");
    {
        auto const key =
            req.headers["Sec-WebSocket-Key"];
        resp.headers.insert("Sec-WebSocket-Key", key);
        resp.headers.insert("Sec-WebSocket-Accept",
            detail::make_sec_ws_accept(key));
    }
    resp.headers.replace("Server", "Beast.WSProto");
    (*d_)(resp);
    http::prepare(resp, http::connection::upgrade);
    return resp;
}

template<class NextLayer>
template<class Body, class Headers>
void
stream<NextLayer>::
do_response(http::response_v1<Body, Headers> const& resp,
    boost::string_ref const& key, error_code& ec)
{
    // VFALCO Review these error codes
    auto fail = [&]{ ec = error::response_failed; };
    if(resp.status != 101)
        return fail();
    if(! is_upgrade(resp))
        return fail();
    if(! rfc2616::ci_equal(
            resp.headers["Upgrade"], "websocket"))
        return fail();
    if(! resp.headers.exists("Sec-WebSocket-Accept"))
        return fail();
    if(resp.headers["Sec-WebSocket-Accept"] !=
        detail::make_sec_ws_accept(key))
        return fail();
    role_ = role_type::client;
}

template<class NextLayer>
void
stream<NextLayer>::
do_read_fh(detail::frame_streambuf& fb,
    close_code::value& code, error_code& ec)
{
    fb.commit(boost::asio::read(
        stream_, fb.prepare(2), ec));
    if(ec)
        return;
    auto const n = detail::read_fh1(
        rd_fh_, fb, role_, code);
    if(code != close_code::none)
        return;
    if(n > 0)
    {
        fb.commit(boost::asio::read(
            stream_, fb.prepare(n), ec));
        if(ec)
            return;
    }
    detail::read_fh2(
        rd_fh_, fb, role_, code);
    if(code != close_code::none)
        return;
    prepare_fh(code);
}

} // websocket
} // beast

#endif