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|
// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012-2022 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License Version 3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
#pragma once
#include <openvpn/common/size.hpp>
#include <openvpn/common/hexstr.hpp>
#include <openvpn/buffer/buffer.hpp>
#include <openvpn/frame/frame.hpp>
namespace openvpn {
namespace WS {
class ChunkedHelper
{
enum State
{
hex,
post_hex,
post_hex_lf,
post_chunk_cr,
post_chunk_lf,
post_content_cr,
post_content_lf,
done,
chunk,
};
public:
ChunkedHelper()
: state(hex),
size(0)
{
}
template <typename PARENT>
bool receive(PARENT &callback, BufferAllocated &buf)
{
while (buf.defined())
{
if (state == chunk)
{
if (size)
{
if (buf.size() <= size)
{
size -= buf.size();
callback.chunked_content_in(buf);
break;
}
else
{
BufferAllocated content(buf.read_alloc(size), size, 0);
size = 0;
callback.chunked_content_in(content);
}
}
else
state = post_chunk_cr;
}
else if (state == done)
break;
else
{
const char c = char(buf.pop_front());
reprocess:
switch (state)
{
case hex:
{
const int v = parse_hex_char(c);
if (v >= 0)
size = (size << 4) + v;
else
{
state = post_hex;
goto reprocess;
}
}
break;
case post_hex:
if (c == '\r')
state = post_hex_lf;
break;
case post_hex_lf:
if (c == '\n')
{
if (size)
state = chunk;
else
state = post_content_cr;
}
else
{
state = post_hex;
goto reprocess;
}
break;
case post_chunk_cr:
if (c == '\r')
state = post_chunk_lf;
break;
case post_chunk_lf:
if (c == '\n')
state = hex;
else
{
state = post_chunk_cr;
goto reprocess;
}
break;
case post_content_cr:
if (c == '\r')
state = post_content_lf;
break;
case post_content_lf:
if (c == '\n')
state = done;
else
{
state = post_content_cr;
goto reprocess;
}
break;
default: // should never be reached
break;
}
}
}
return state == done;
}
static BufferPtr transmit(BufferPtr buf)
{
const size_t headroom = 24;
const size_t tailroom = 16;
static const char crlf[] = "\r\n";
if (!buf || buf->offset() < headroom || buf->remaining() < tailroom)
{
// insufficient headroom/tailroom, must realloc
Frame::Context fc(headroom, 0, tailroom, 0, sizeof(size_t), 0);
buf = fc.copy(buf);
}
size_t size = buf->size();
buf->prepend((unsigned char *)crlf, 2);
if (size)
{
while (size)
{
char *pc = (char *)buf->prepend_alloc(1);
*pc = render_hex_char(size & 0xF);
size >>= 4;
}
}
else
{
char *pc = (char *)buf->prepend_alloc(1);
*pc = '0';
}
buf->write((unsigned char *)crlf, 2);
return buf;
}
private:
State state;
size_t size;
};
} // namespace WS
} // namespace openvpn
|
