414 lines
9.0 KiB
C++
414 lines
9.0 KiB
C++
/*
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Copyright (c) 2003, Arvid Norberg
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TORRENT_BENCODE_HPP_INCLUDED
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#define TORRENT_BENCODE_HPP_INCLUDED
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/*
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* This file declares the following functions:
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*
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*----------------------------------
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* template<class OutIt>
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* void libtorrent::bencode(OutIt out, const libtorrent::entry& e);
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*
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* Encodes a message entry with bencoding into the output
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* iterator given. The bencoding is described in the BitTorrent
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* protocol description document OutIt must be an OutputIterator
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* of type char. This may throw libtorrent::invalid_encoding if
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* the entry contains invalid nodes (undefined_t for example).
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*
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*----------------------------------
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* template<class InIt>
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* libtorrent::entry libtorrent::bdecode(InIt start, InIt end);
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*
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* Decodes the buffer given by the start and end iterators
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* and returns the decoded entry. InIt must be an InputIterator
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* of type char. May throw libtorrent::invalid_encoding if
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* the string is not correctly bencoded.
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*
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*/
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#include <cstdlib>
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#ifdef _MSC_VER
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#pragma warning(push, 1)
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#endif
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#include <boost/lexical_cast.hpp>
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#include <boost/static_assert.hpp>
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#ifdef _MSC_VER
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#pragma warning(pop)
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#endif
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#include "libtorrent/entry.hpp"
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#include "libtorrent/config.hpp"
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#include "libtorrent/assert.hpp"
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#if defined(_MSC_VER)
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namespace std
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{
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using ::isdigit;
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using ::atoi;
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};
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#define for if (false) {} else for
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#endif
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namespace libtorrent
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{
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struct TORRENT_EXPORT invalid_encoding: std::exception
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{
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virtual const char* what() const throw() { return "invalid bencoding"; }
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};
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namespace detail
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{
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template <class OutIt>
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int write_string(OutIt& out, const std::string& val)
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{
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for (std::string::const_iterator i = val.begin()
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, end(val.end()); i != end; ++i)
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*out++ = *i;
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return val.length();
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}
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TORRENT_EXPORT char const* integer_to_str(char* buf, int size, entry::integer_type val);
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template <class OutIt>
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int write_integer(OutIt& out, entry::integer_type val)
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{
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// the stack allocated buffer for keeping the
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// decimal representation of the number can
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// not hold number bigger than this:
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BOOST_STATIC_ASSERT(sizeof(entry::integer_type) <= 8);
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char buf[21];
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int ret = 0;
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for (char const* str = integer_to_str(buf, 21, val);
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*str != 0; ++str)
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{
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*out = *str;
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++out;
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++ret;
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}
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return ret;
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}
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template <class OutIt>
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void write_char(OutIt& out, char c)
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{
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*out = c;
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++out;
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}
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template <class InIt>
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std::string read_until(InIt& in, InIt end, char end_token, bool& err)
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{
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std::string ret;
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if (in == end)
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{
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err = true;
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return ret;
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}
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while (*in != end_token)
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{
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ret += *in;
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++in;
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if (in == end)
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{
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err = true;
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return ret;
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}
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}
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return ret;
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}
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template<class InIt>
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void read_string(InIt& in, InIt end, int len, std::string& str, bool& err)
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{
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TORRENT_ASSERT(len >= 0);
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for (int i = 0; i < len; ++i)
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{
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if (in == end)
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{
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err = true;
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return;
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}
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str += *in;
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++in;
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}
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}
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// returns the number of bytes written
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template<class OutIt>
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int bencode_recursive(OutIt& out, const entry& e)
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{
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int ret = 0;
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switch(e.type())
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{
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case entry::int_t:
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write_char(out, 'i');
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ret += write_integer(out, e.integer());
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write_char(out, 'e');
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ret += 2;
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break;
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case entry::string_t:
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ret += write_integer(out, e.string().length());
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write_char(out, ':');
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ret += write_string(out, e.string());
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ret += 1;
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break;
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case entry::list_t:
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write_char(out, 'l');
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for (entry::list_type::const_iterator i = e.list().begin(); i != e.list().end(); ++i)
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ret += bencode_recursive(out, *i);
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write_char(out, 'e');
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ret += 2;
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break;
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case entry::dictionary_t:
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write_char(out, 'd');
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for (entry::dictionary_type::const_iterator i = e.dict().begin();
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i != e.dict().end(); ++i)
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{
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// write key
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ret += write_integer(out, i->first.length());
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write_char(out, ':');
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ret += write_string(out, i->first);
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// write value
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ret += bencode_recursive(out, i->second);
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ret += 1;
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}
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write_char(out, 'e');
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ret += 2;
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break;
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default:
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// do nothing
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break;
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}
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return ret;
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}
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template<class InIt>
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void bdecode_recursive(InIt& in, InIt end, entry& ret, bool& err, int depth)
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{
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if (depth >= 100)
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{
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err = true;
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return;
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}
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if (in == end)
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{
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err = true;
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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switch (*in)
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{
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// ----------------------------------------------
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// integer
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case 'i':
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{
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++in; // 'i'
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std::string val = read_until(in, end, 'e', err);
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if (err) return;
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TORRENT_ASSERT(*in == 'e');
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++in; // 'e'
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ret = entry(entry::int_t);
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ret.integer() = boost::lexical_cast<entry::integer_type>(val);
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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} break;
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// ----------------------------------------------
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// list
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case 'l':
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{
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ret = entry(entry::list_t);
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++in; // 'l'
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while (*in != 'e')
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{
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ret.list().push_back(entry());
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entry& e = ret.list().back();
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bdecode_recursive(in, end, e, err, depth + 1);
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if (err)
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{
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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if (in == end)
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{
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err = true;
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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}
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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TORRENT_ASSERT(*in == 'e');
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++in; // 'e'
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} break;
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// ----------------------------------------------
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// dictionary
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case 'd':
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{
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ret = entry(entry::dictionary_t);
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++in; // 'd'
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while (*in != 'e')
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{
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entry key;
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bdecode_recursive(in, end, key, err, depth + 1);
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if (err || key.type() != entry::string_t)
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{
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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entry& e = ret[key.string()];
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bdecode_recursive(in, end, e, err, depth + 1);
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if (err)
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{
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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if (in == end)
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{
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err = true;
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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}
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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TORRENT_ASSERT(*in == 'e');
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++in; // 'e'
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} break;
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// ----------------------------------------------
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// string
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default:
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if (isdigit((unsigned char)*in))
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{
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std::string len_s = read_until(in, end, ':', err);
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if (err)
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{
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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TORRENT_ASSERT(*in == ':');
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++in; // ':'
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int len = std::atoi(len_s.c_str());
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ret = entry(entry::string_t);
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read_string(in, end, len, ret.string(), err);
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if (err)
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{
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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}
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else
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{
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err = true;
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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return;
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}
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#ifndef NDEBUG
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ret.m_type_queried = false;
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#endif
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}
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}
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}
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template<class OutIt>
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int bencode(OutIt out, const entry& e)
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{
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return detail::bencode_recursive(out, e);
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}
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template<class InIt>
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entry bdecode(InIt start, InIt end)
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{
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entry e;
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bool err = false;
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detail::bdecode_recursive(start, end, e, err, 0);
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TORRENT_ASSERT(e.m_type_queried == false);
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if (err) return entry();
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return e;
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}
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template<class InIt>
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entry bdecode(InIt start, InIt end, int& len)
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{
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entry e;
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bool err = false;
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InIt s = start;
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detail::bdecode_recursive(start, end, e, err, 0);
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len = std::distance(s, start);
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TORRENT_ASSERT(len >= 0);
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if (err) return entry();
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return e;
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}
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}
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#endif // TORRENT_BENCODE_HPP_INCLUDED
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