forked from premiere/premiere-libtorrent
435 lines
17 KiB
C++
435 lines
17 KiB
C++
/*
|
|
|
|
Copyright (c) 2015-2016, Arvid Norberg
|
|
All rights reserved.
|
|
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions
|
|
are met:
|
|
|
|
* Redistributions of source code must retain the above copyright
|
|
notice, this list of conditions and the following disclaimer.
|
|
* Redistributions in binary form must reproduce the above copyright
|
|
notice, this list of conditions and the following disclaimer in
|
|
the documentation and/or other materials provided with the distribution.
|
|
* Neither the name of the author nor the names of its
|
|
contributors may be used to endorse or promote products derived
|
|
from this software without specific prior written permission.
|
|
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
*/
|
|
|
|
#ifndef TORRENT_BDECODE_HPP
|
|
#define TORRENT_BDECODE_HPP
|
|
|
|
#include <vector>
|
|
#include <string>
|
|
#include <cstdint>
|
|
#include <cstddef>
|
|
|
|
#include "libtorrent/aux_/disable_warnings_push.hpp"
|
|
#include <boost/system/error_code.hpp>
|
|
#include "libtorrent/aux_/disable_warnings_pop.hpp"
|
|
|
|
#include "libtorrent/assert.hpp"
|
|
#include "libtorrent/span.hpp"
|
|
#include "libtorrent/string_view.hpp"
|
|
|
|
/*
|
|
|
|
This is an efficient bdecoder. It decodes into a flat memory buffer of tokens.
|
|
|
|
Each token has an offset into the bencoded buffer where the token came from
|
|
and a next pointer, which is a relative number of tokens to skip forward to
|
|
get to the logical next item in a container.
|
|
|
|
strings and ints offset pointers point to the first character of the length
|
|
prefix or the 'i' character. This is to maintain uniformity with other types
|
|
and to allow easily calculating the span of a node by subtracting its offset
|
|
by the offset of the next node.
|
|
|
|
example layout:
|
|
|
|
{
|
|
"a": { "b": 1, "c": "abcd" },
|
|
"d": 3
|
|
}
|
|
|
|
/---------------------------------------------------------------------------------------\
|
|
| |
|
|
| |
|
|
| /--------------------------------------------\ |
|
|
| | | |
|
|
| | | |
|
|
| /-----\ | /----\ /----\ /----\ /----\ | /----\ /----\ |
|
|
| next | | | | | | | | | | | | | | | | |
|
|
| pointers | v | | v | v | v | v v | v | v v
|
|
+-+-----+----+--+----+--+----+--+----+--+----+--+----+--+-------+----+--+----+--+------+ X
|
|
| dict | str | dict | str | int | str | str | end | str | int | end |
|
|
| | | | | | | | | | | |
|
|
| | | | | | | | | | | |
|
|
+-+-----+-+-----+-+-----+-+-----+-+-----+-+-----+-+-----+-+-----+-+-----+-+-----+-+----+
|
|
| offset| | | | | | | | | |
|
|
| | | | | | | | | | |
|
|
|/------/ | | | | | | | | |
|
|
|| /-----------/ | | | | | | | |
|
|
|| |/------------------/ | | | | | | |
|
|
|| || /-----------------------/ | | | | | |
|
|
|| || | /----------------------------/ | | | | |
|
|
|| || | | /---------------------------------/ | | | |
|
|
|| || | | | /-----------------------------------/ | | |
|
|
|| || | | | |/------------------------------------------/ | |
|
|
|| || | | | || /-----------------------------------------------/ |
|
|
|| || | | | || | /----------------------------------------------------/
|
|
|| || | | | || | |
|
|
vv vv v v v vv v v
|
|
``d1:ad1:bi1e1:c4:abcde1:di3ee``
|
|
|
|
*/
|
|
|
|
namespace libtorrent {
|
|
|
|
TORRENT_EXPORT boost::system::error_category& bdecode_category();
|
|
|
|
#ifndef TORRENT_NO_DEPRECATED
|
|
TORRENT_DEPRECATED
|
|
inline boost::system::error_category& get_bdecode_category()
|
|
{ return bdecode_category(); }
|
|
#endif
|
|
|
|
namespace bdecode_errors
|
|
{
|
|
// libtorrent uses boost.system's ``error_code`` class to represent
|
|
// errors. libtorrent has its own error category bdecode_category()
|
|
// with the error codes defined by error_code_enum.
|
|
enum error_code_enum
|
|
{
|
|
// Not an error
|
|
no_error = 0,
|
|
// expected digit in bencoded string
|
|
expected_digit,
|
|
// expected colon in bencoded string
|
|
expected_colon,
|
|
// unexpected end of file in bencoded string
|
|
unexpected_eof,
|
|
// expected value (list, dict, int or string) in bencoded string
|
|
expected_value,
|
|
// bencoded recursion depth limit exceeded
|
|
depth_exceeded,
|
|
// bencoded item count limit exceeded
|
|
limit_exceeded,
|
|
// integer overflow
|
|
overflow,
|
|
|
|
// the number of error codes
|
|
error_code_max
|
|
};
|
|
|
|
// hidden
|
|
TORRENT_EXPORT boost::system::error_code make_error_code(error_code_enum e);
|
|
}
|
|
} // namespace libtorrent
|
|
|
|
namespace boost { namespace system {
|
|
|
|
template<> struct is_error_code_enum<libtorrent::bdecode_errors::error_code_enum>
|
|
{ static const bool value = true; };
|
|
|
|
} }
|
|
|
|
namespace libtorrent {
|
|
|
|
typedef boost::system::error_code error_code;
|
|
|
|
TORRENT_EXTRA_EXPORT char const* parse_int(char const* start
|
|
, char const* end, char delimiter, std::int64_t& val
|
|
, bdecode_errors::error_code_enum& ec);
|
|
|
|
namespace detail {
|
|
|
|
// internal
|
|
struct bdecode_token
|
|
{
|
|
// the node with type 'end' is a logical node, pointing to the end
|
|
// of the bencoded buffer.
|
|
enum type_t
|
|
{ none, dict, list, string, integer, end };
|
|
|
|
enum limits_t
|
|
{
|
|
max_offset = (1 << 29) - 1,
|
|
max_next_item = (1 << 29) - 1,
|
|
max_header = (1 << 3) - 1
|
|
};
|
|
|
|
bdecode_token(std::ptrdiff_t off, bdecode_token::type_t t)
|
|
: offset(std::uint32_t(off))
|
|
, type(t)
|
|
, next_item(0)
|
|
, header(0)
|
|
{
|
|
TORRENT_ASSERT(off >= 0);
|
|
TORRENT_ASSERT(off <= max_offset);
|
|
TORRENT_ASSERT(t >= 0 && t <= end);
|
|
}
|
|
|
|
bdecode_token(std::ptrdiff_t off, std::uint32_t next
|
|
, bdecode_token::type_t t, std::uint8_t header_size = 0)
|
|
: offset(std::uint32_t(off))
|
|
, type(t)
|
|
, next_item(next)
|
|
, header(type == string ? std::uint32_t(header_size - 2) : 0)
|
|
{
|
|
TORRENT_ASSERT(type != string || header_size >= 2);
|
|
TORRENT_ASSERT(off >= 0);
|
|
TORRENT_ASSERT(off <= max_offset);
|
|
TORRENT_ASSERT(next <= max_next_item);
|
|
// the string has 2 implied header bytes, to allow for longer prefixes
|
|
TORRENT_ASSERT(header_size < 8 || (type == string && header_size < 10));
|
|
TORRENT_ASSERT(t >= 0 && t <= end);
|
|
}
|
|
|
|
int start_offset() const { TORRENT_ASSERT(type == string); return int(header) + 2; }
|
|
|
|
// offset into the bdecoded buffer where this node is
|
|
std::uint32_t offset:29;
|
|
|
|
// one of type_t enums
|
|
std::uint32_t type:3;
|
|
|
|
// if this node is a member of a list, 'next_item' is the number of nodes
|
|
// to jump forward in th node array to get to the next item in the list.
|
|
// if it's a key in a dictionary, it's the number of step forwards to get
|
|
// to its corresponding value. If it's a value in a dictionary, it's the
|
|
// number of steps to the next key, or to the end node.
|
|
// this is the _relative_ offset to the next node
|
|
std::uint32_t next_item:29;
|
|
|
|
// this is the number of bytes to skip forward from the offset to get to the
|
|
// first character of the string, if this is a string. This field is not
|
|
// used for other types. Essentially this is the length of the length prefix
|
|
// and the colon. Since a string always has at least one character of length
|
|
// prefix and always a colon, those 2 characters are implied.
|
|
std::uint32_t header:3;
|
|
};
|
|
}
|
|
|
|
// a ``bdecode_node`` is used to traverse and hold the tree structure defined
|
|
// by bencoded data after it has been parse by bdecode().
|
|
//
|
|
// There are primarily two kinds of bdecode_nodes. The ones that own the tree
|
|
// structure, and defines its lifetime, and nodes that are child nodes in the
|
|
// tree, pointing back into the root's tree.
|
|
//
|
|
// The ``bdecode_node`` passed in to ``bdecode()`` becomes the one owning the
|
|
// tree structure. Make sure not to destruct that object for as long as you
|
|
// use any of its child nodes. Also, keep in mind that the buffer originally
|
|
// parsed also must remain valid while using it. (see switch_underlying_buffer()).
|
|
//
|
|
// Copying an owning node will create a copy of the whole tree, but will still
|
|
// point into the same parsed bencoded buffer as the first one.
|
|
|
|
// Sometimes it's important to get a non-owning reference to the root node (
|
|
// to be able to copy it as a reference for instance). For that, use the
|
|
// non_owning() member function.
|
|
//
|
|
// There are 5 different types of nodes, see type_t.
|
|
struct TORRENT_EXPORT bdecode_node
|
|
{
|
|
// TODO: 3 deprecate this overload
|
|
TORRENT_EXPORT friend int bdecode(char const* start, char const* end, bdecode_node& ret
|
|
, error_code& ec, int* error_pos, int depth_limit
|
|
, int token_limit);
|
|
|
|
TORRENT_EXPORT friend bdecode_node bdecode(span<char const> buffer
|
|
, error_code& ec, int* error_pos, int depth_limit, int token_limit);
|
|
|
|
// creates a default constructed node, it will have the type ``none_t``.
|
|
bdecode_node();
|
|
|
|
// For owning nodes, the copy will create a copy of the tree, but the
|
|
// underlying buffer remains the same.
|
|
bdecode_node(bdecode_node const&);
|
|
bdecode_node& operator=(bdecode_node const&);
|
|
bdecode_node(bdecode_node&&) noexcept;
|
|
bdecode_node& operator=(bdecode_node&&) noexcept;
|
|
|
|
// the types of bdecoded nodes
|
|
enum type_t
|
|
{
|
|
// uninitialized or default constructed. This is also used
|
|
// to indicate that a node was not found in some cases.
|
|
none_t,
|
|
// a dictionary node. The ``dict_find_`` functions are valid.
|
|
dict_t,
|
|
// a list node. The ``list_`` functions are valid.
|
|
list_t,
|
|
// a string node, the ``string_`` functions are valid.
|
|
string_t,
|
|
// an integer node. The ``int_`` functions are valid.
|
|
int_t
|
|
};
|
|
|
|
// the type of this node. See type_t.
|
|
type_t type() const;
|
|
|
|
// returns true if type() != none_t.
|
|
explicit operator bool() const;
|
|
|
|
// return a non-owning reference to this node. This is useful to refer to
|
|
// the root node without copying it in assignments.
|
|
bdecode_node non_owning() const;
|
|
|
|
// returns the buffer and length of the section in the original bencoded
|
|
// buffer where this node is defined. For a dictionary for instance, this
|
|
// starts with ``d`` and ends with ``e``, and has all the content of the
|
|
// dictionary in between.
|
|
span<char const> data_section() const;
|
|
|
|
// functions with the ``list_`` prefix operate on lists. These functions are
|
|
// only valid if ``type()`` == ``list_t``. ``list_at()`` returns the item
|
|
// in the list at index ``i``. ``i`` may not be greater than or equal to the
|
|
// size of the list. ``size()`` returns the size of the list.
|
|
bdecode_node list_at(int i) const;
|
|
string_view list_string_value_at(int i
|
|
, string_view default_val = string_view()) const;
|
|
std::int64_t list_int_value_at(int i
|
|
, std::int64_t default_val = 0) const;
|
|
int list_size() const;
|
|
|
|
// Functions with the ``dict_`` prefix operates on dictionaries. They are
|
|
// only valid if ``type()`` == ``dict_t``. In case a key you're looking up
|
|
// contains a 0 byte, you cannot use the 0-terminated string overloads,
|
|
// but have to use ``std::string`` instead. ``dict_find_list`` will return a
|
|
// valid ``bdecode_node`` if the key is found _and_ it is a list. Otherwise
|
|
// it will return a default-constructed bdecode_node.
|
|
//
|
|
// Functions with the ``_value`` suffix return the value of the node
|
|
// directly, rather than the nodes. In case the node is not found, or it has
|
|
// a different type, a default value is returned (which can be specified).
|
|
bdecode_node dict_find(string_view key) const;
|
|
std::pair<string_view, bdecode_node> dict_at(int i) const;
|
|
bdecode_node dict_find_dict(string_view key) const;
|
|
bdecode_node dict_find_list(string_view key) const;
|
|
bdecode_node dict_find_string(string_view key) const;
|
|
bdecode_node dict_find_int(string_view key) const;
|
|
string_view dict_find_string_value(string_view key
|
|
, string_view default_value = string_view()) const;
|
|
std::int64_t dict_find_int_value(string_view key
|
|
, std::int64_t default_val = 0) const;
|
|
int dict_size() const;
|
|
|
|
// this function is only valid if ``type()`` == ``int_t``. It returns the
|
|
// value of the integer.
|
|
std::int64_t int_value() const;
|
|
|
|
// these functions are only valid if ``type()`` == ``string_t``. They return
|
|
// the string values. Note that ``string_ptr()`` is *not* 0-terminated.
|
|
// ``string_length()`` returns the number of bytes in the string.
|
|
string_view string_value() const;
|
|
char const* string_ptr() const;
|
|
int string_length() const;
|
|
|
|
// resets the ``bdecoded_node`` to a default constructed state. If this is
|
|
// an owning node, the tree is freed and all child nodes are invalidated.
|
|
void clear();
|
|
|
|
// Swap contents.
|
|
void swap(bdecode_node& n);
|
|
|
|
// pre-allocate memory for the specified numbers of tokens. This is
|
|
// useful if you know approximately how many tokens are in the file
|
|
// you are about to parse. Doing so will save realloc operations
|
|
// while parsing. You should only call this on the root node, before
|
|
// passing it in to bdecode().
|
|
void reserve(int tokens);
|
|
|
|
// this buffer *MUST* be identical to the one originally parsed. This
|
|
// operation is only defined on owning root nodes, i.e. the one passed in to
|
|
// decode().
|
|
void switch_underlying_buffer(char const* buf);
|
|
|
|
private:
|
|
bdecode_node(detail::bdecode_token const* tokens, char const* buf
|
|
, int len, int idx);
|
|
|
|
// if this is the root node, that owns all the tokens, they live in this
|
|
// vector. If this is a sub-node, this field is not used, instead the
|
|
// m_root_tokens pointer points to the root node's token.
|
|
std::vector<detail::bdecode_token> m_tokens;
|
|
|
|
// this points to the root nodes token vector
|
|
// for the root node, this points to its own m_tokens member
|
|
detail::bdecode_token const* m_root_tokens;
|
|
|
|
// this points to the original buffer that was parsed
|
|
char const* m_buffer;
|
|
int m_buffer_size;
|
|
|
|
// this is the index into m_root_tokens that this node refers to
|
|
// for the root node, it's 0. -1 means uninitialized.
|
|
int m_token_idx;
|
|
|
|
// this is a cache of the last element index looked up. This only applies
|
|
// to lists and dictionaries. If the next lookup is at m_last_index or
|
|
// greater, we can start iterating the tokens at m_last_token.
|
|
mutable int m_last_index;
|
|
mutable int m_last_token;
|
|
|
|
// the number of elements in this list or dict (computed on the first
|
|
// call to dict_size() or list_size())
|
|
mutable int m_size;
|
|
};
|
|
|
|
// print the bencoded structure in a human-readable format to a string
|
|
// that's returned.
|
|
TORRENT_EXPORT std::string print_entry(bdecode_node const& e
|
|
, bool single_line = false, int indent = 0);
|
|
|
|
// This function decodes/parses bdecoded data (for example a .torrent file).
|
|
// The data structure is returned in the ``ret`` argument. the buffer to parse
|
|
// is specified by the ``start`` of the buffer as well as the ``end``, i.e. one
|
|
// byte past the end. If the buffer fails to parse, the function returns a
|
|
// non-zero value and fills in ``ec`` with the error code. The optional
|
|
// argument ``error_pos``, if set to non-nullptr, will be set to the byte offset
|
|
// into the buffer where the parse failure occurred.
|
|
//
|
|
// ``depth_limit`` specifies the max number of nested lists or dictionaries are
|
|
// allowed in the data structure. (This affects the stack usage of the
|
|
// function, be careful not to set it too high).
|
|
//
|
|
// ``token_limit`` is the max number of tokens allowed to be parsed from the
|
|
// buffer. This is simply a sanity check to not have unbounded memory usage.
|
|
//
|
|
// The resulting ``bdecode_node`` is an *owning* node. That means it will
|
|
// be holding the whole parsed tree. When iterating lists and dictionaries,
|
|
// those ``bdecode_node`` objects will simply have references to the root or
|
|
// owning ``bdecode_node``. If the root node is destructed, all other nodes
|
|
// that refer to anything in that tree become invalid.
|
|
//
|
|
// However, the underlying buffer passed in to this function (``start``, ``end``)
|
|
// must also remain valid while the bdecoded tree is used. The parsed tree
|
|
// produced by this function does not copy any data out of the buffer, but
|
|
// simply produces references back into it.
|
|
TORRENT_EXPORT int bdecode(char const* start, char const* end, bdecode_node& ret
|
|
, error_code& ec, int* error_pos = nullptr, int depth_limit = 100
|
|
, int token_limit = 1000000);
|
|
TORRENT_EXPORT bdecode_node bdecode(span<char const> buffer
|
|
, error_code& ec, int* error_pos = nullptr, int depth_limit = 100
|
|
, int token_limit = 1000000);
|
|
|
|
}
|
|
|
|
#endif // TORRENT_BDECODE_HPP
|