[ViewVC] Diff of: cvs/CBOR-XS/XS.pm

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.27 by root, Thu Nov 28 15:43:24 2013 UTC vs.
Revision 1.70 by root, Sat Nov 9 07:30:36 2019 UTC

…		…
26	substr $many_cbor_strings, 0, $length, ""; # remove decoded cbor string	26	substr $many_cbor_strings, 0, $length, ""; # remove decoded cbor string
27	}	27	}
28		28
29	=head1 DESCRIPTION	29	=head1 DESCRIPTION
30		30
31	WARNING! This module is very new, and not very well tested (that's up
32	to you to do). Furthermore, details of the implementation might change
33	freely before version 1.0. And lastly, most extensions depend on an IANA
34	assignment, and until that assignment is official, this implementation is
35	not interoperable with other implementations (even future versions of this
36	module) until the assignment is done.
37
38	You are still invited to try out CBOR, and this module.
39
40	This module converts Perl data structures to the Concise Binary Object	31	This module converts Perl data structures to the Concise Binary Object
41	Representation (CBOR) and vice versa. CBOR is a fast binary serialisation	32	Representation (CBOR) and vice versa. CBOR is a fast binary serialisation
42	format that aims to use a superset of the JSON data model, i.e. when you	33	format that aims to use an (almost) superset of the JSON data model, i.e.
43	can represent something in JSON, you should be able to represent it in	34	when you can represent something useful in JSON, you should be able to
44	CBOR.	35	represent it in CBOR.
45		36
46	In short, CBOR is a faster and very compact binary alternative to JSON,	37	In short, CBOR is a faster and quite compact binary alternative to JSON,
47	with the added ability of supporting serialisation of Perl objects. (JSON	38	with the added ability of supporting serialisation of Perl objects. (JSON
48	often compresses better than CBOR though, so if you plan to compress the	39	often compresses better than CBOR though, so if you plan to compress the
49	data later you might want to compare both formats first).	40	data later and speed is less important you might want to compare both
		41	formats first).
		42
		43	The primary goal of this module is to be I<correct> and the secondary goal
		44	is to be I<fast>. To reach the latter goal it was written in C.
50		45
51	To give you a general idea about speed, with texts in the megabyte range,	46	To give you a general idea about speed, with texts in the megabyte range,
52	C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or	47	C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or
53	L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the	48	L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the
54	data, the worse L<Storable> performs in comparison.	49	data, the worse L<Storable> performs in comparison.
55		50
56	As for compactness, C<CBOR::XS> encoded data structures are usually about	51	Regarding compactness, C<CBOR::XS>-encoded data structures are usually
57	20% smaller than the same data encoded as (compact) JSON or L<Storable>.	52	about 20% smaller than the same data encoded as (compact) JSON or
		53	L<Storable>.
58		54
59	In addition to the core CBOR data format, this module implements a number	55	In addition to the core CBOR data format, this module implements a
60	of extensions, to support cyclic and self-referencing data structures	56	number of extensions, to support cyclic and shared data structures
61	(see C<allow_sharing>), string deduplication (see C<pack_strings>) and	57	(see C<allow_sharing> and C<allow_cycles>), string deduplication (see
62	scalar references (always enabled).	58	C<pack_strings>) and scalar references (always enabled).
63
64	The primary goal of this module is to be I<correct> and the secondary goal
65	is to be I<fast>. To reach the latter goal it was written in C.
66		59
67	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and	60	See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
68	vice versa.	61	vice versa.
69		62
70	=cut	63	=cut
71		64
72	package CBOR::XS;	65	package CBOR::XS;
73		66
74	use common::sense;	67	use common::sense;
75		68
76	our $VERSION = 0.09;	69	our $VERSION = 1.71;
77	our @ISA = qw(Exporter);	70	our @ISA = qw(Exporter);
78		71
79	our @EXPORT = qw(encode_cbor decode_cbor);	72	our @EXPORT = qw(encode_cbor decode_cbor);
80		73
81	use Exporter;	74	use Exporter;
…		…
119		112
120	The mutators for flags all return the CBOR object again and thus calls can	113	The mutators for flags all return the CBOR object again and thus calls can
121	be chained:	114	be chained:
122		115
123	my $cbor = CBOR::XS->new->encode ({a => [1,2]});	116	my $cbor = CBOR::XS->new->encode ({a => [1,2]});
		117
		118	=item $cbor = new_safe CBOR::XS
		119
		120	Create a new, safe/secure CBOR::XS object. This is similar to C<new>,
		121	but configures the coder object to be safe to use with untrusted
		122	data. Currently, this is equivalent to:
		123
		124	my $cbor = CBOR::XS
		125	->new
		126	->forbid_objects
		127	->filter (\&CBOR::XS::safe_filter)
		128	->max_size (1e8);
		129
		130	But is more future proof (it is better to crash because of a change than
		131	to be exploited in other ways).
		132
		133	=cut
		134
		135	sub new_safe {
		136	CBOR::XS
		137	->new
		138	->forbid_objects
		139	->filter (\&CBOR::XS::safe_filter)
		140	->max_size (1e8)
		141	}
124		142
125	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])	143	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])
126		144
127	=item $max_depth = $cbor->get_max_depth	145	=item $max_depth = $cbor->get_max_depth
128		146
…		…
144		162
145	Note that nesting is implemented by recursion in C. The default value has	163	Note that nesting is implemented by recursion in C. The default value has
146	been chosen to be as large as typical operating systems allow without	164	been chosen to be as large as typical operating systems allow without
147	crashing.	165	crashing.
148		166
149	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	167	See L<SECURITY CONSIDERATIONS>, below, for more info on why this is useful.
150		168
151	=item $cbor = $cbor->max_size ([$maximum_string_size])	169	=item $cbor = $cbor->max_size ([$maximum_string_size])
152		170
153	=item $max_size = $cbor->get_max_size	171	=item $max_size = $cbor->get_max_size
154		172
…		…
159	effect on C<encode> (yet).	177	effect on C<encode> (yet).
160		178
161	If no argument is given, the limit check will be deactivated (same as when	179	If no argument is given, the limit check will be deactivated (same as when
162	C<0> is specified).	180	C<0> is specified).
163		181
164	See SECURITY CONSIDERATIONS, below, for more info on why this is useful.	182	See L<SECURITY CONSIDERATIONS>, below, for more info on why this is useful.
165		183
166	=item $cbor = $cbor->allow_unknown ([$enable])	184	=item $cbor = $cbor->allow_unknown ([$enable])
167		185
168	=item $enabled = $cbor->get_allow_unknown	186	=item $enabled = $cbor->get_allow_unknown
169		187
…		…
187	reference to the earlier value.	205	reference to the earlier value.
188		206
189	This means that such values will only be encoded once, and will not result	207	This means that such values will only be encoded once, and will not result
190	in a deep cloning of the value on decode, in decoders supporting the value	208	in a deep cloning of the value on decode, in decoders supporting the value
191	sharing extension. This also makes it possible to encode cyclic data	209	sharing extension. This also makes it possible to encode cyclic data
192	structures.	210	structures (which need C<allow_cycles> to be enabled to be decoded by this
		211	module).
193		212
194	It is recommended to leave it off unless you know your	213	It is recommended to leave it off unless you know your
195	communication partner supports the value sharing extensions to CBOR	214	communication partner supports the value sharing extensions to CBOR
196	(L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the	215	(L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the
197	resulting data structure might be unusable.	216	resulting data structure might be unusable.
198		217
199	Detecting shared values incurs a runtime overhead when values are encoded	218	Detecting shared values incurs a runtime overhead when values are encoded
200	that have a reference counter large than one, and might unnecessarily	219	that have a reference counter large than one, and might unnecessarily
201	increase the encoded size, as potentially shared values are encode as	220	increase the encoded size, as potentially shared values are encoded as
202	sharable whether or not they are actually shared.	221	shareable whether or not they are actually shared.
203		222
204	At the moment, only targets of references can be shared (e.g. scalars,	223	At the moment, only targets of references can be shared (e.g. scalars,
205	arrays or hashes pointed to by a reference). Weirder constructs, such as	224	arrays or hashes pointed to by a reference). Weirder constructs, such as
206	an array with multiple "copies" of the I<same> string, which are hard but	225	an array with multiple "copies" of the I<same> string, which are hard but
207	not impossible to create in Perl, are not supported (this is the same as	226	not impossible to create in Perl, are not supported (this is the same as
…		…
212	structures cannot be encoded in this mode.	231	structures cannot be encoded in this mode.
213		232
214	This option does not affect C<decode> in any way - shared values and	233	This option does not affect C<decode> in any way - shared values and
215	references will always be decoded properly if present.	234	references will always be decoded properly if present.
216		235
		236	=item $cbor = $cbor->allow_cycles ([$enable])
		237
		238	=item $enabled = $cbor->get_allow_cycles
		239
		240	If C<$enable> is true (or missing), then C<decode> will happily decode
		241	self-referential (cyclic) data structures. By default these will not be
		242	decoded, as they need manual cleanup to avoid memory leaks, so code that
		243	isn't prepared for this will not leak memory.
		244
		245	If C<$enable> is false (the default), then C<decode> will throw an error
		246	when it encounters a self-referential/cyclic data structure.
		247
		248	FUTURE DIRECTION: the motivation behind this option is to avoid I<real>
		249	cycles - future versions of this module might chose to decode cyclic data
		250	structures using weak references when this option is off, instead of
		251	throwing an error.
		252
		253	This option does not affect C<encode> in any way - shared values and
		254	references will always be encoded properly if present.
		255
		256	=item $cbor = $cbor->forbid_objects ([$enable])
		257
		258	=item $enabled = $cbor->get_forbid_objects
		259
		260	Disables the use of the object serialiser protocol.
		261
		262	If C<$enable> is true (or missing), then C<encode> will will throw an
		263	exception when it encounters perl objects that would be encoded using the
		264	perl-object tag (26). When C<decode> encounters such tags, it will fall
		265	back to the general filter/tagged logic as if this were an unknown tag (by
		266	default resulting in a C<CBOR::XC::Tagged> object).
		267
		268	If C<$enable> is false (the default), then C<encode> will use the
		269	L<Types::Serialiser> object serialisation protocol to serialise objects
		270	into perl-object tags, and C<decode> will do the same to decode such tags.
		271
		272	See L<SECURITY CONSIDERATIONS>, below, for more info on why forbidding this
		273	protocol can be useful.
		274
217	=item $cbor = $cbor->pack_strings ([$enable])	275	=item $cbor = $cbor->pack_strings ([$enable])
218		276
219	=item $enabled = $cbor->get_pack_strings	277	=item $enabled = $cbor->get_pack_strings
220		278
221	If C<$enable> is true (or missing), then C<encode> will try not to encode	279	If C<$enable> is true (or missing), then C<encode> will try not to encode
…		…
233	the standard CBOR way.	291	the standard CBOR way.
234		292
235	This option does not affect C<decode> in any way - string references will	293	This option does not affect C<decode> in any way - string references will
236	always be decoded properly if present.	294	always be decoded properly if present.
237		295
		296	=item $cbor = $cbor->text_keys ([$enable])
		297
		298	=item $enabled = $cbor->get_text_keys
		299
		300	If C<$enabled> is true (or missing), then C<encode> will encode all
		301	perl hash keys as CBOR text strings/UTF-8 string, upgrading them as needed.
		302
		303	If C<$enable> is false (the default), then C<encode> will encode hash keys
		304	normally - upgraded perl strings (strings internally encoded as UTF-8) as
		305	CBOR text strings, and downgraded perl strings as CBOR byte strings.
		306
		307	This option does not affect C<decode> in any way.
		308
		309	This option is useful for interoperability with CBOR decoders that don't
		310	treat byte strings as a form of text. It is especially useful as Perl
		311	gives very little control over hash keys.
		312
		313	Enabling this option can be slow, as all downgraded hash keys that are
		314	encoded need to be scanned and converted to UTF-8.
		315
		316	=item $cbor = $cbor->text_strings ([$enable])
		317
		318	=item $enabled = $cbor->get_text_strings
		319
		320	This option works similar to C<text_keys>, above, but works on all strings
		321	(including hash keys), so C<text_keys> has no further effect after
		322	enabling C<text_strings>.
		323
		324	If C<$enabled> is true (or missing), then C<encode> will encode all perl
		325	strings as CBOR text strings/UTF-8 strings, upgrading them as needed.
		326
		327	If C<$enable> is false (the default), then C<encode> will encode strings
		328	normally (but see C<text_keys>) - upgraded perl strings (strings
		329	internally encoded as UTF-8) as CBOR text strings, and downgraded perl
		330	strings as CBOR byte strings.
		331
		332	This option does not affect C<decode> in any way.
		333
		334	This option has similar advantages and disadvantages as C<text_keys>. In
		335	addition, this option effectively removes the ability to encode byte
		336	strings, which might break some C<FREEZE> and C<TO_CBOR> methods that rely
		337	on this, such as bignum encoding, so this option is mainly useful for very
		338	simple data.
		339
		340	=item $cbor = $cbor->validate_utf8 ([$enable])
		341
		342	=item $enabled = $cbor->get_validate_utf8
		343
		344	If C<$enable> is true (or missing), then C<decode> will validate that
		345	elements (text strings) containing UTF-8 data in fact contain valid UTF-8
		346	data (instead of blindly accepting it). This validation obviously takes
		347	extra time during decoding.
		348
		349	The concept of "valid UTF-8" used is perl's concept, which is a superset
		350	of the official UTF-8.
		351
		352	If C<$enable> is false (the default), then C<decode> will blindly accept
		353	UTF-8 data, marking them as valid UTF-8 in the resulting data structure
		354	regardless of whether that's true or not.
		355
		356	Perl isn't too happy about corrupted UTF-8 in strings, but should
		357	generally not crash or do similarly evil things. Extensions might be not
		358	so forgiving, so it's recommended to turn on this setting if you receive
		359	untrusted CBOR.
		360
		361	This option does not affect C<encode> in any way - strings that are
		362	supposedly valid UTF-8 will simply be dumped into the resulting CBOR
		363	string without checking whether that is, in fact, true or not.
		364
238	=item $cbor = $cbor->filter ([$cb->($tag, $value)])	365	=item $cbor = $cbor->filter ([$cb->($tag, $value)])
239		366
240	=item $cb_or_undef = $cbor->get_filter	367	=item $cb_or_undef = $cbor->get_filter
241		368
242	Sets or replaces the tagged value decoding filter (when C<$cb> is	369	Sets or replaces the tagged value decoding filter (when C<$cb> is
…		…
254	replace the tagged value in the decoded data structure, or no values,	381	replace the tagged value in the decoded data structure, or no values,
255	which will result in default handling, which currently means the decoder	382	which will result in default handling, which currently means the decoder
256	creates a C<CBOR::XS::Tagged> object to hold the tag and the value.	383	creates a C<CBOR::XS::Tagged> object to hold the tag and the value.
257		384
258	When the filter is cleared (the default state), the default filter	385	When the filter is cleared (the default state), the default filter
259	function, C<CBOR::XS::default_filter>, is used. This function simply looks	386	function, C<CBOR::XS::default_filter>, is used. This function simply
260	up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be	387	looks up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists
261	a code reference that is called with tag and value, and is responsible for	388	it must be a code reference that is called with tag and value, and is
262	decoding the value. If no entry exists, it returns no values.	389	responsible for decoding the value. If no entry exists, it returns no
		390	values. C<CBOR::XS> provides a number of default filter functions already,
		391	the the C<%CBOR::XS::FILTER> hash can be freely extended with more.
263		392
		393	C<CBOR::XS> additionally provides an alternative filter function that is
		394	supposed to be safe to use with untrusted data (which the default filter
		395	might not), called C<CBOR::XS::safe_filter>, which works the same as
		396	the C<default_filter> but uses the C<%CBOR::XS::SAFE_FILTER> variable
		397	instead. It is prepopulated with the tag decoding functions that are
		398	deemed safe (basically the same as C<%CBOR::XS::FILTER> without all
		399	the bignum tags), and can be extended by user code as wlel, although,
		400	obviously, one should be very careful about adding decoding functions
		401	here, since the expectation is that they are safe to use on untrusted
		402	data, after all.
		403
264	Example: decode all tags not handled internally into CBOR::XS::Tagged	404	Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
265	objects, with no other special handling (useful when working with	405	objects, with no other special handling (useful when working with
266	potentially "unsafe" CBOR data).	406	potentially "unsafe" CBOR data).
267		407
268	CBOR::XS->new->filter (sub { })->decode ($cbor_data);	408	CBOR::XS->new->filter (sub { })->decode ($cbor_data);
269		409
…		…
273	$CBOR::XS::FILTER{1347375694} = sub {	413	$CBOR::XS::FILTER{1347375694} = sub {
274	my ($tag, $value);	414	my ($tag, $value);
275		415
276	"tag 1347375694 value $value"	416	"tag 1347375694 value $value"
277	};	417	};
		418
		419	Example: provide your own filter function that looks up tags in your own
		420	hash:
		421
		422	my %my_filter = (
		423	998347484 => sub {
		424	my ($tag, $value);
		425
		426	"tag 998347484 value $value"
		427	};
		428	);
		429
		430	my $coder = CBOR::XS->new->filter (sub {
		431	&{ $my_filter{$_[0]} or return }
		432	});
		433
		434
		435	Example: use the safe filter function (see L<SECURITY CONSIDERATIONS> for
		436	more considerations on security).
		437
		438	CBOR::XS->new->filter (\&CBOR::XS::safe_filter)->decode ($cbor_data);
278		439
279	=item $cbor_data = $cbor->encode ($perl_scalar)	440	=item $cbor_data = $cbor->encode ($perl_scalar)
280		441
281	Converts the given Perl data structure (a scalar value) to its CBOR	442	Converts the given Perl data structure (a scalar value) to its CBOR
282	representation.	443	representation.
…		…
292	when there is trailing garbage after the CBOR string, it will silently	453	when there is trailing garbage after the CBOR string, it will silently
293	stop parsing there and return the number of characters consumed so far.	454	stop parsing there and return the number of characters consumed so far.
294		455
295	This is useful if your CBOR texts are not delimited by an outer protocol	456	This is useful if your CBOR texts are not delimited by an outer protocol
296	and you need to know where the first CBOR string ends amd the next one	457	and you need to know where the first CBOR string ends amd the next one
297	starts.	458	starts - CBOR strings are self-delimited, so it is possible to concatenate
		459	CBOR strings without any delimiters or size fields and recover their data.
298		460
299	CBOR::XS->new->decode_prefix ("......")	461	CBOR::XS->new->decode_prefix ("......")
300	=> ("...", 3)	462	=> ("...", 3)
		463
		464	=back
		465
		466	=head2 INCREMENTAL PARSING
		467
		468	In some cases, there is the need for incremental parsing of JSON
		469	texts. While this module always has to keep both CBOR text and resulting
		470	Perl data structure in memory at one time, it does allow you to parse a
		471	CBOR stream incrementally, using a similar to using "decode_prefix" to see
		472	if a full CBOR object is available, but is much more efficient.
		473
		474	It basically works by parsing as much of a CBOR string as possible - if
		475	the CBOR data is not complete yet, the pasrer will remember where it was,
		476	to be able to restart when more data has been accumulated. Once enough
		477	data is available to either decode a complete CBOR value or raise an
		478	error, a real decode will be attempted.
		479
		480	A typical use case would be a network protocol that consists of sending
		481	and receiving CBOR-encoded messages. The solution that works with CBOR and
		482	about anything else is by prepending a length to every CBOR value, so the
		483	receiver knows how many octets to read. More compact (and slightly slower)
		484	would be to just send CBOR values back-to-back, as C<CBOR::XS> knows where
		485	a CBOR value ends, and doesn't need an explicit length.
		486
		487	The following methods help with this:
		488
		489	=over 4
		490
		491	=item @decoded = $cbor->incr_parse ($buffer)
		492
		493	This method attempts to decode exactly one CBOR value from the beginning
		494	of the given C<$buffer>. The value is removed from the C<$buffer> on
		495	success. When C<$buffer> doesn't contain a complete value yet, it returns
		496	nothing. Finally, when the C<$buffer> doesn't start with something
		497	that could ever be a valid CBOR value, it raises an exception, just as
		498	C<decode> would. In the latter case the decoder state is undefined and
		499	must be reset before being able to parse further.
		500
		501	This method modifies the C<$buffer> in place. When no CBOR value can be
		502	decoded, the decoder stores the current string offset. On the next call,
		503	continues decoding at the place where it stopped before. For this to make
		504	sense, the C<$buffer> must begin with the same octets as on previous
		505	unsuccessful calls.
		506
		507	You can call this method in scalar context, in which case it either
		508	returns a decoded value or C<undef>. This makes it impossible to
		509	distinguish between CBOR null values (which decode to C<undef>) and an
		510	unsuccessful decode, which is often acceptable.
		511
		512	=item @decoded = $cbor->incr_parse_multiple ($buffer)
		513
		514	Same as C<incr_parse>, but attempts to decode as many CBOR values as
		515	possible in one go, instead of at most one. Calls to C<incr_parse> and
		516	C<incr_parse_multiple> can be interleaved.
		517
		518	=item $cbor->incr_reset
		519
		520	Resets the incremental decoder. This throws away any saved state, so that
		521	subsequent calls to C<incr_parse> or C<incr_parse_multiple> start to parse
		522	a new CBOR value from the beginning of the C<$buffer> again.
		523
		524	This method can be called at any time, but it I<must> be called if you want
		525	to change your C<$buffer> or there was a decoding error and you want to
		526	reuse the C<$cbor> object for future incremental parsings.
301		527
302	=back	528	=back
303		529
304		530
305	=head1 MAPPING	531	=head1 MAPPING
…		…
356	=item tagged values	582	=item tagged values
357		583
358	Tagged items consists of a numeric tag and another CBOR value.	584	Tagged items consists of a numeric tag and another CBOR value.
359		585
360	See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>	586	See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>
361	for details.	587	for details on which tags are handled how.
362		588
363	=item anything else	589	=item anything else
364		590
365	Anything else (e.g. unsupported simple values) will raise a decoding	591	Anything else (e.g. unsupported simple values) will raise a decoding
366	error.	592	error.
…		…
369		595
370		596
371	=head2 PERL -> CBOR	597	=head2 PERL -> CBOR
372		598
373	The mapping from Perl to CBOR is slightly more difficult, as Perl is a	599	The mapping from Perl to CBOR is slightly more difficult, as Perl is a
374	truly typeless language, so we can only guess which CBOR type is meant by	600	typeless language. That means this module can only guess which CBOR type
375	a Perl value.	601	is meant by a perl value.
376		602
377	=over 4	603	=over 4
378		604
379	=item hash references	605	=item hash references
380		606
381	Perl hash references become CBOR maps. As there is no inherent ordering in	607	Perl hash references become CBOR maps. As there is no inherent ordering in
382	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random	608	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
383	order.	609	order. This order can be different each time a hash is encoded.
384		610
385	Currently, tied hashes will use the indefinite-length format, while normal	611	Currently, tied hashes will use the indefinite-length format, while normal
386	hashes will use the fixed-length format.	612	hashes will use the fixed-length format.
387		613
388	=item array references	614	=item array references
389		615
390	Perl array references become fixed-length CBOR arrays.	616	Perl array references become fixed-length CBOR arrays.
391		617
392	=item other references	618	=item other references
393		619
394	Other unblessed references are generally not allowed and will cause an	620	Other unblessed references will be represented using
395	exception to be thrown, except for references to the integers C<0> and	621	the indirection tag extension (tag value C<22098>,
396	C<1>, which get turned into false and true in CBOR.	622	L<http://cbor.schmorp.de/indirection>). CBOR decoders are guaranteed
		623	to be able to decode these values somehow, by either "doing the right
		624	thing", decoding into a generic tagged object, simply ignoring the tag, or
		625	something else.
397		626
398	=item CBOR::XS::Tagged objects	627	=item CBOR::XS::Tagged objects
399		628
400	Objects of this type must be arrays consisting of a single C<[tag, value]>	629	Objects of this type must be arrays consisting of a single C<[tag, value]>
401	pair. The (numerical) tag will be encoded as a CBOR tag, the value will	630	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
402	be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to	631	be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to
403	create such objects.	632	create such objects.
404		633
405	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	634	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
406		635
407	These special values become CBOR true, CBOR false and CBOR undefined	636	These special values become CBOR true, CBOR false and CBOR undefined
…		…
438	my $x = 3.1; # some variable containing a number	667	my $x = 3.1; # some variable containing a number
439	"$x"; # stringified	668	"$x"; # stringified
440	$x .= ""; # another, more awkward way to stringify	669	$x .= ""; # another, more awkward way to stringify
441	print $x; # perl does it for you, too, quite often	670	print $x; # perl does it for you, too, quite often
442		671
443	You can force whether a string ie encoded as byte or text string by using	672	You can force whether a string is encoded as byte or text string by using
444	C<utf8::upgrade> and C<utf8::downgrade>):	673	C<utf8::upgrade> and C<utf8::downgrade> (if C<text_strings> is disabled):
445		674
446	utf8::upgrade $x; # encode $x as text string	675	utf8::upgrade $x; # encode $x as text string
447	utf8::downgrade $x; # encode $x as byte string	676	utf8::downgrade $x; # encode $x as byte string
448		677
449	Perl doesn't define what operations up- and downgrade strings, so if the	678	Perl doesn't define what operations up- and downgrade strings, so if the
450	difference between byte and text is important, you should up- or downgrade	679	difference between byte and text is important, you should up- or downgrade
451	your string as late as possible before encoding.	680	your string as late as possible before encoding. You can also force the
		681	use of CBOR text strings by using C<text_keys> or C<text_strings>.
452		682
453	You can force the type to be a CBOR number by numifying it:	683	You can force the type to be a CBOR number by numifying it:
454		684
455	my $x = "3"; # some variable containing a string	685	my $x = "3"; # some variable containing a string
456	$x += 0; # numify it, ensuring it will be dumped as a number	686	$x += 0; # numify it, ensuring it will be dumped as a number
…		…
469		699
470	=back	700	=back
471		701
472	=head2 OBJECT SERIALISATION	702	=head2 OBJECT SERIALISATION
473		703
		704	This module implements both a CBOR-specific and the generic
		705	L<Types::Serialier> object serialisation protocol. The following
		706	subsections explain both methods.
		707
		708	=head3 ENCODING
		709
474	This module knows two way to serialise a Perl object: The CBOR-specific	710	This module knows two way to serialise a Perl object: The CBOR-specific
475	way, and the generic way.	711	way, and the generic way.
476		712
477	Whenever the encoder encounters a Perl object that it cnanot serialise	713	Whenever the encoder encounters a Perl object that it cannot serialise
478	directly (most of them), it will first look up the C<TO_CBOR> method on	714	directly (most of them), it will first look up the C<TO_CBOR> method on
479	it.	715	it.
480		716
481	If it has a C<TO_CBOR> method, it will call it with the object as only	717	If it has a C<TO_CBOR> method, it will call it with the object as only
482	argument, and expects exactly one return value, which it will then	718	argument, and expects exactly one return value, which it will then
…		…
488		724
489	The C<FREEZE> method can return any number of values (i.e. zero or	725	The C<FREEZE> method can return any number of values (i.e. zero or
490	more). These will be encoded as CBOR perl object, together with the	726	more). These will be encoded as CBOR perl object, together with the
491	classname.	727	classname.
492		728
		729	These methods I<MUST NOT> change the data structure that is being
		730	serialised. Failure to comply to this can result in memory corruption -
		731	and worse.
		732
493	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail	733	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
494	with an error.	734	with an error.
495		735
		736	=head3 DECODING
		737
496	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but	738	Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
497	objects encoded via C<FREEZE> can be decoded using the following protocol:	739	but objects encoded via C<FREEZE> can be decoded using the following
		740	protocol:
498		741
499	When an encoded CBOR perl object is encountered by the decoder, it will	742	When an encoded CBOR perl object is encountered by the decoder, it will
500	look up the C<THAW> method, by using the stored classname, and will fail	743	look up the C<THAW> method, by using the stored classname, and will fail
501	if the method cannot be found.	744	if the method cannot be found.
502		745
503	After the lookup it will call the C<THAW> method with the stored classname	746	After the lookup it will call the C<THAW> method with the stored classname
504	as first argument, the constant string C<CBOR> as second argument, and all	747	as first argument, the constant string C<CBOR> as second argument, and all
505	values returned by C<FREEZE> as remaining arguments.	748	values returned by C<FREEZE> as remaining arguments.
506		749
507	=head4 EXAMPLES	750	=head3 EXAMPLES
508		751
509	Here is an example C<TO_CBOR> method:	752	Here is an example C<TO_CBOR> method:
510		753
511	sub My::Object::TO_CBOR {	754	sub My::Object::TO_CBOR {
512	my ($obj) = @_;	755	my ($obj) = @_;
…		…
523		766
524	sub URI::TO_CBOR {	767	sub URI::TO_CBOR {
525	my ($self) = @_;	768	my ($self) = @_;
526	my $uri = "$self"; # stringify uri	769	my $uri = "$self"; # stringify uri
527	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string	770	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
528	CBOR::XS::tagged 32, "$_[0]"	771	CBOR::XS::tag 32, "$_[0]"
529	}	772	}
530		773
531	This will encode URIs as a UTF-8 string with tag 32, which indicates an	774	This will encode URIs as a UTF-8 string with tag 32, which indicates an
532	URI.	775	URI.
533		776
…		…
544	"$self" # encode url string	787	"$self" # encode url string
545	}	788	}
546		789
547	sub URI::THAW {	790	sub URI::THAW {
548	my ($class, $serialiser, $uri) = @_;	791	my ($class, $serialiser, $uri) = @_;
549
550	$class->new ($uri)	792	$class->new ($uri)
551	}	793	}
552		794
553	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For	795	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
554	example, a C<FREEZE> method that returns "type", "id" and "variant" values	796	example, a C<FREEZE> method that returns "type", "id" and "variant" values
…		…
685	additional tags (such as base64url).	927	additional tags (such as base64url).
686		928
687	=head2 ENFORCED TAGS	929	=head2 ENFORCED TAGS
688		930
689	These tags are always handled when decoding, and their handling cannot be	931	These tags are always handled when decoding, and their handling cannot be
690	overriden by the user.	932	overridden by the user.
691		933
692	=over 4	934	=over 4
693		935
694	=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)	936	=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
695		937
696	These tags are automatically created (and decoded) for serialisable	938	These tags are automatically created (and decoded) for serialisable
697	objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object	939	objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
698	serialisation protocol). See L<OBJECT SERIALISATION> for details.	940	serialisation protocol). See L<OBJECT SERIALISATION> for details.
699		941
700	=item 28, 29 (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>)	942	=item 28, 29 (shareable, sharedref, L<http://cbor.schmorp.de/value-sharing>)
701		943
702	These tags are automatically decoded when encountered, resulting in	944	These tags are automatically decoded when encountered (and they do not
		945	result in a cyclic data structure, see C<allow_cycles>), resulting in
703	shared values in the decoded object. They are only encoded, however, when	946	shared values in the decoded object. They are only encoded, however, when
704	C<allow_sharable> is enabled.	947	C<allow_sharing> is enabled.
705		948
		949	Not all shared values can be successfully decoded: values that reference
		950	themselves will I<currently> decode as C<undef> (this is not the same
		951	as a reference pointing to itself, which will be represented as a value
		952	that contains an indirect reference to itself - these will be decoded
		953	properly).
		954
		955	Note that considerably more shared value data structures can be decoded
		956	than will be encoded - currently, only values pointed to by references
		957	will be shared, others will not. While non-reference shared values can be
		958	generated in Perl with some effort, they were considered too unimportant
		959	to be supported in the encoder. The decoder, however, will decode these
		960	values as shared values.
		961
706	=item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>)	962	=item 256, 25 (stringref-namespace, stringref, L<http://cbor.schmorp.de/stringref>)
707		963
708	These tags are automatically decoded when encountered. They are only	964	These tags are automatically decoded when encountered. They are only
709	encoded, however, when C<pack_strings> is enabled.	965	encoded, however, when C<pack_strings> is enabled.
710		966
711	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)	967	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
712		968
713	This tag is automatically generated when a reference are encountered (with	969	This tag is automatically generated when a reference are encountered (with
714	the exception of hash and array refernces). It is converted to a reference	970	the exception of hash and array references). It is converted to a reference
715	when decoding.	971	when decoding.
716		972
717	=item 55799 (self-describe CBOR, RFC 7049)	973	=item 55799 (self-describe CBOR, RFC 7049)
718		974
719	This value is not generated on encoding (unless explicitly requested by	975	This value is not generated on encoding (unless explicitly requested by
…		…
722	=back	978	=back
723		979
724	=head2 NON-ENFORCED TAGS	980	=head2 NON-ENFORCED TAGS
725		981
726	These tags have default filters provided when decoding. Their handling can	982	These tags have default filters provided when decoding. Their handling can
727	be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by	983	be overridden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
728	providing a custom C<filter> callback when decoding.	984	providing a custom C<filter> callback when decoding.
729		985
730	When they result in decoding into a specific Perl class, the module	986	When they result in decoding into a specific Perl class, the module
731	usually provides a corresponding C<TO_CBOR> method as well.	987	usually provides a corresponding C<TO_CBOR> method as well.
732		988
…		…
735	provide these modules. The decoding usually fails with an exception if the	991	provide these modules. The decoding usually fails with an exception if the
736	required module cannot be loaded.	992	required module cannot be loaded.
737		993
738	=over 4	994	=over 4
739		995
		996	=item 0, 1 (date/time string, seconds since the epoch)
		997
		998	These tags are decoded into L<Time::Piece> objects. The corresponding
		999	C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently.
		1000
		1001	The L<Time::Piece> API is generally surprisingly bad, and fractional
		1002	seconds are only accidentally kept intact, so watch out. On the plus side,
		1003	the module comes with perl since 5.10, which has to count for something.
		1004
740	=item 2, 3 (positive/negative bignum)	1005	=item 2, 3 (positive/negative bignum)
741		1006
742	These tags are decoded into L<Math::BigInt> objects. The corresponding	1007	These tags are decoded into L<Math::BigInt> objects. The corresponding
743	C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR	1008	C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
744	integers, and others into positive/negative CBOR bignums.	1009	integers, and others into positive/negative CBOR bignums.
745		1010
746	=item 4, 5 (decimal fraction/bigfloat)	1011	=item 4, 5, 264, 265 (decimal fraction/bigfloat)
747		1012
748	Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>	1013	Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>
749	objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>	1014	objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>
750	encodes into a decimal fraction.	1015	encodes into a decimal fraction (either tag 4 or 264).
751		1016
752	CBOR cannot represent bigfloats with I<very> large exponents - conversion	1017	NaN and infinities are not encoded properly, as they cannot be represented
753	of such big float objects is undefined.	1018	in CBOR.
754		1019
755	Also, NaN and infinities are not encoded properly.	1020	See L<BIGNUM SECURITY CONSIDERATIONS> for more info.
		1021
		1022	=item 30 (rational numbers)
		1023
		1024	These tags are decoded into L<Math::BigRat> objects. The corresponding
		1025	C<Math::BigRat::TO_CBOR> method encodes rational numbers with denominator
		1026	C<1> via their numerator only, i.e., they become normal integers or
		1027	C<bignums>.
		1028
		1029	See L<BIGNUM SECURITY CONSIDERATIONS> for more info.
756		1030
757	=item 21, 22, 23 (expected later JSON conversion)	1031	=item 21, 22, 23 (expected later JSON conversion)
758		1032
759	CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these	1033	CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these
760	tags.	1034	tags.
…		…
765	C<URI::TO_CBOR> method again results in a CBOR URI value.	1039	C<URI::TO_CBOR> method again results in a CBOR URI value.
766		1040
767	=back	1041	=back
768		1042
769	=cut	1043	=cut
770
771	our %FILTER = (
772	# 0 # rfc4287 datetime, utf-8
773	# 1 # unix timestamp, any
774
775	2 => sub { # pos bigint
776	require Math::BigInt;
777	Math::BigInt->new ("0x" . unpack "H*", pop)
778	},
779
780	3 => sub { # neg bigint
781	require Math::BigInt;
782	-Math::BigInt->new ("0x" . unpack "H*", pop)
783	},
784
785	4 => sub { # decimal fraction, array
786	require Math::BigFloat;
787	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
788	},
789
790	5 => sub { # bigfloat, array
791	require Math::BigFloat;
792	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
793	},
794
795	21 => sub { pop }, # expected conversion to base64url encoding
796	22 => sub { pop }, # expected conversion to base64 encoding
797	23 => sub { pop }, # expected conversion to base16 encoding
798
799	# 24 # embedded cbor, byte string
800
801	32 => sub {
802	require URI;
803	URI->new (pop)
804	},
805
806	# 33 # base64url rfc4648, utf-8
807	# 34 # base64 rfc46484, utf-8
808	# 35 # regex pcre/ecma262, utf-8
809	# 36 # mime message rfc2045, utf-8
810	);
811
812		1044
813	=head1 CBOR and JSON	1045	=head1 CBOR and JSON
814		1046
815	CBOR is supposed to implement a superset of the JSON data model, and is,	1047	CBOR is supposed to implement a superset of the JSON data model, and is,
816	with some coercion, able to represent all JSON texts (something that other	1048	with some coercion, able to represent all JSON texts (something that other
…		…
825	CBOR intact.	1057	CBOR intact.
826		1058
827		1059
828	=head1 SECURITY CONSIDERATIONS	1060	=head1 SECURITY CONSIDERATIONS
829		1061
830	When you are using CBOR in a protocol, talking to untrusted potentially	1062	Tl;dr... if you want to decode or encode CBOR from untrusted sources, you
831	hostile creatures requires relatively few measures.	1063	should start with a coder object created via C<new_safe> (which implements
		1064	the mitigations explained below):
832		1065
		1066	my $coder = CBOR::XS->new_safe;
		1067
		1068	my $data = $coder->decode ($cbor_text);
		1069	my $cbor = $coder->encode ($data);
		1070
		1071	Longer version: When you are using CBOR in a protocol, talking to
		1072	untrusted potentially hostile creatures requires some thought:
		1073
		1074	=over 4
		1075
		1076	=item Security of the CBOR decoder itself
		1077
833	First of all, your CBOR decoder should be secure, that is, should not have	1078	First and foremost, your CBOR decoder should be secure, that is, should
		1079	not have any buffer overflows or similar bugs that could potentially be
834	any buffer overflows. Obviously, this module should ensure that and I am	1080	exploited. Obviously, this module should ensure that and I am trying hard
835	trying hard on making that true, but you never know.	1081	on making that true, but you never know.
836		1082
		1083	=item CBOR::XS can invoke almost arbitrary callbacks during decoding
		1084
		1085	CBOR::XS supports object serialisation - decoding CBOR can cause calls
		1086	to I<any> C<THAW> method in I<any> package that exists in your process
		1087	(that is, CBOR::XS will not try to load modules, but any existing C<THAW>
		1088	method or function can be called, so they all have to be secure).
		1089
		1090	Less obviously, it will also invoke C<TO_CBOR> and C<FREEZE> methods -
		1091	even if all your C<THAW> methods are secure, encoding data structures from
		1092	untrusted sources can invoke those and trigger bugs in those.
		1093
		1094	So, if you are not sure about the security of all the modules you
		1095	have loaded (you shouldn't), you should disable this part using
		1096	C<forbid_objects> or using C<new_safe>.
		1097
		1098	=item CBOR can be extended with tags that call library code
		1099
		1100	CBOR can be extended with tags, and C<CBOR::XS> has a registry of
		1101	conversion functions for many existing tags that can be extended via
		1102	third-party modules (see the C<filter> method).
		1103
		1104	If you don't trust these, you should configure the "safe" filter function,
		1105	C<CBOR::XS::safe_filter> (C<new_safe> does this), which by default only
		1106	includes conversion functions that are considered "safe" by the author
		1107	(but again, they can be extended by third party modules).
		1108
		1109	Depending on your level of paranoia, you can use the "safe" filter:
		1110
		1111	$cbor->filter (\&CBOR::XS::safe_filter);
		1112
		1113	... your own filter...
		1114
		1115	$cbor->filter (sub { ... do your stuffs here ... });
		1116
		1117	... or even no filter at all, disabling all tag decoding:
		1118
		1119	$cbor->filter (sub { });
		1120
		1121	This is never a problem for encoding, as the tag mechanism only exists in
		1122	CBOR texts.
		1123
		1124	=item Resource-starving attacks: object memory usage
		1125
837	Second, you need to avoid resource-starving attacks. That means you should	1126	You need to avoid resource-starving attacks. That means you should limit
838	limit the size of CBOR data you accept, or make sure then when your	1127	the size of CBOR data you accept, or make sure then when your resources
839	resources run out, that's just fine (e.g. by using a separate process that	1128	run out, that's just fine (e.g. by using a separate process that can
840	can crash safely). The size of a CBOR string in octets is usually a good	1129	crash safely). The size of a CBOR string in octets is usually a good
841	indication of the size of the resources required to decode it into a Perl	1130	indication of the size of the resources required to decode it into a Perl
842	structure. While CBOR::XS can check the size of the CBOR text, it might be	1131	structure. While CBOR::XS can check the size of the CBOR text (using
843	too late when you already have it in memory, so you might want to check	1132	C<max_size> - done by C<new_safe>), it might be too late when you already
844	the size before you accept the string.	1133	have it in memory, so you might want to check the size before you accept
		1134	the string.
845		1135
		1136	As for encoding, it is possible to construct data structures that are
		1137	relatively small but result in large CBOR texts (for example by having an
		1138	array full of references to the same big data structure, which will all be
		1139	deep-cloned during encoding by default). This is rarely an actual issue
		1140	(and the worst case is still just running out of memory), but you can
		1141	reduce this risk by using C<allow_sharing>.
		1142
		1143	=item Resource-starving attacks: stack overflows
		1144
846	Third, CBOR::XS recurses using the C stack when decoding objects and	1145	CBOR::XS recurses using the C stack when decoding objects and arrays. The
847	arrays. The C stack is a limited resource: for instance, on my amd64	1146	C stack is a limited resource: for instance, on my amd64 machine with 8MB
848	machine with 8MB of stack size I can decode around 180k nested arrays but	1147	of stack size I can decode around 180k nested arrays but only 14k nested
849	only 14k nested CBOR objects (due to perl itself recursing deeply on croak	1148	CBOR objects (due to perl itself recursing deeply on croak to free the
850	to free the temporary). If that is exceeded, the program crashes. To be	1149	temporary). If that is exceeded, the program crashes. To be conservative,
851	conservative, the default nesting limit is set to 512. If your process	1150	the default nesting limit is set to 512. If your process has a smaller
852	has a smaller stack, you should adjust this setting accordingly with the	1151	stack, you should adjust this setting accordingly with the C<max_depth>
853	C<max_depth> method.	1152	method.
		1153
		1154	=item Resource-starving attacks: CPU en-/decoding complexity
		1155
		1156	CBOR::XS will use the L<Math::BigInt>, L<Math::BigFloat> and
		1157	L<Math::BigRat> libraries to represent encode/decode bignums. These can be
		1158	very slow (as in, centuries of CPU time) and can even crash your program
		1159	(and are generally not very trustworthy). See the next section on bignum
		1160	security for details.
		1161
		1162	=item Data breaches: leaking information in error messages
		1163
		1164	CBOR::XS might leak contents of your Perl data structures in its error
		1165	messages, so when you serialise sensitive information you might want to
		1166	make sure that exceptions thrown by CBOR::XS will not end up in front of
		1167	untrusted eyes.
		1168
		1169	=item Something else...
854		1170
855	Something else could bomb you, too, that I forgot to think of. In that	1171	Something else could bomb you, too, that I forgot to think of. In that
856	case, you get to keep the pieces. I am always open for hints, though...	1172	case, you get to keep the pieces. I am always open for hints, though...
857		1173
858	Also keep in mind that CBOR::XS might leak contents of your Perl data	1174	=back
859	structures in its error messages, so when you serialise sensitive	1175
860	information you might want to make sure that exceptions thrown by CBOR::XS	1176
861	will not end up in front of untrusted eyes.	1177	=head1 BIGNUM SECURITY CONSIDERATIONS
		1178
		1179	CBOR::XS provides a C<TO_CBOR> method for both L<Math::BigInt> and
		1180	L<Math::BigFloat> that tries to encode the number in the simplest possible
		1181	way, that is, either a CBOR integer, a CBOR bigint/decimal fraction (tag
		1182	4) or an arbitrary-exponent decimal fraction (tag 264). Rational numbers
		1183	(L<Math::BigRat>, tag 30) can also contain bignums as members.
		1184
		1185	CBOR::XS will also understand base-2 bigfloat or arbitrary-exponent
		1186	bigfloats (tags 5 and 265), but it will never generate these on its own.
		1187
		1188	Using the built-in L<Math::BigInt::Calc> support, encoding and decoding
		1189	decimal fractions is generally fast. Decoding bigints can be slow for very
		1190	big numbers (tens of thousands of digits, something that could potentially
		1191	be caught by limiting the size of CBOR texts), and decoding bigfloats or
		1192	arbitrary-exponent bigfloats can be I<extremely> slow (minutes, decades)
		1193	for large exponents (roughly 40 bit and longer).
		1194
		1195	Additionally, L<Math::BigInt> can take advantage of other bignum
		1196	libraries, such as L<Math::GMP>, which cannot handle big floats with large
		1197	exponents, and might simply abort or crash your program, due to their code
		1198	quality.
		1199
		1200	This can be a concern if you want to parse untrusted CBOR. If it is, you
		1201	might want to disable decoding of tag 2 (bigint) and 3 (negative bigint)
		1202	types. You should also disable types 5 and 265, as these can be slow even
		1203	without bigints.
		1204
		1205	Disabling bigints will also partially or fully disable types that rely on
		1206	them, e.g. rational numbers that use bignums.
		1207
862		1208
863	=head1 CBOR IMPLEMENTATION NOTES	1209	=head1 CBOR IMPLEMENTATION NOTES
864		1210
865	This section contains some random implementation notes. They do not	1211	This section contains some random implementation notes. They do not
866	describe guaranteed behaviour, but merely behaviour as-is implemented	1212	describe guaranteed behaviour, but merely behaviour as-is implemented
…		…
875	Only the double data type is supported for NV data types - when Perl uses	1221	Only the double data type is supported for NV data types - when Perl uses
876	long double to represent floating point values, they might not be encoded	1222	long double to represent floating point values, they might not be encoded
877	properly. Half precision types are accepted, but not encoded.	1223	properly. Half precision types are accepted, but not encoded.
878		1224
879	Strict mode and canonical mode are not implemented.	1225	Strict mode and canonical mode are not implemented.
		1226
		1227
		1228	=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
		1229
		1230	On perls that were built without 64 bit integer support (these are rare
		1231	nowadays, even on 32 bit architectures, as all major Perl distributions
		1232	are built with 64 bit integer support), support for any kind of 64 bit
		1233	integer in CBOR is very limited - most likely, these 64 bit values will
		1234	be truncated, corrupted, or otherwise not decoded correctly. This also
		1235	includes string, array and map sizes that are stored as 64 bit integers.
880		1236
881		1237
882	=head1 THREADS	1238	=head1 THREADS
883		1239
884	This module is I<not> guaranteed to be thread safe and there are no	1240	This module is I<not> guaranteed to be thread safe and there are no
…		…
898	Please refrain from using rt.cpan.org or any other bug reporting	1254	Please refrain from using rt.cpan.org or any other bug reporting
899	service. I put the contact address into my modules for a reason.	1255	service. I put the contact address into my modules for a reason.
900		1256
901	=cut	1257	=cut
902		1258
		1259	# clumsy and slow hv_store-in-hash helper function
		1260	sub _hv_store {
		1261	$_[0]{$_[1]} = $_[2];
		1262	}
		1263
903	our %FILTER = (	1264	our %FILTER = (
904	# 0 # rfc4287 datetime, utf-8	1265	0 => sub { # rfc4287 datetime, utf-8
905	# 1 # unix timestamp, any	1266	require Time::Piece;
		1267	# Time::Piece::Strptime uses the "incredibly flexible date parsing routine"
		1268	# from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything
		1269	# else either. Whats incredibe over standard strptime totally escapes me.
		1270	# doesn't do fractional times, either. sigh.
		1271	# In fact, it's all a lie, it uses whatever strptime it wants, and of course,
		1272	# they are all incompatible. The openbsd one simply ignores %z (but according to the
		1273	# docs, it would be much more incredibly flexible indeed. If it worked, that is.).
		1274	scalar eval {
		1275	my $s = $_[1];
		1276
		1277	$s =~ s/Z$/+00:00/;
		1278	$s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$//
		1279	or die;
		1280
		1281	my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully
		1282	my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S");
		1283
		1284	Time::Piece::gmtime ($d->epoch + $b)
		1285	} \|\| die "corrupted CBOR date/time string ($_[0])";
		1286	},
		1287
		1288	1 => sub { # seconds since the epoch, possibly fractional
		1289	require Time::Piece;
		1290	scalar Time::Piece::gmtime (pop)
		1291	},
906		1292
907	2 => sub { # pos bigint	1293	2 => sub { # pos bigint
908	require Math::BigInt;	1294	require Math::BigInt;
909	Math::BigInt->new ("0x" . unpack "H*", pop)	1295	Math::BigInt->new ("0x" . unpack "H*", pop)
910	},	1296	},
…		…
917	4 => sub { # decimal fraction, array	1303	4 => sub { # decimal fraction, array
918	require Math::BigFloat;	1304	require Math::BigFloat;
919	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])	1305	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
920	},	1306	},
921		1307
		1308	264 => sub { # decimal fraction with arbitrary exponent
		1309	require Math::BigFloat;
		1310	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		1311	},
		1312
922	5 => sub { # bigfloat, array	1313	5 => sub { # bigfloat, array
923	require Math::BigFloat;	1314	require Math::BigFloat;
924	scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)	1315	scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
		1316	},
		1317
		1318	265 => sub { # bigfloat with arbitrary exponent
		1319	require Math::BigFloat;
		1320	scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
		1321	},
		1322
		1323	30 => sub { # rational number
		1324	require Math::BigRat;
		1325	Math::BigRat->new ("$_[1][0]/$_[1][1]") # separate parameters only work in recent versons
925	},	1326	},
926		1327
927	21 => sub { pop }, # expected conversion to base64url encoding	1328	21 => sub { pop }, # expected conversion to base64url encoding
928	22 => sub { pop }, # expected conversion to base64 encoding	1329	22 => sub { pop }, # expected conversion to base64 encoding
929	23 => sub { pop }, # expected conversion to base16 encoding	1330	23 => sub { pop }, # expected conversion to base16 encoding
…		…
939	# 34 # base64 rfc46484, utf-8	1340	# 34 # base64 rfc46484, utf-8
940	# 35 # regex pcre/ecma262, utf-8	1341	# 35 # regex pcre/ecma262, utf-8
941	# 36 # mime message rfc2045, utf-8	1342	# 36 # mime message rfc2045, utf-8
942	);	1343	);
943		1344
944	sub CBOR::XS::default_filter {	1345	sub default_filter {
945	&{ $FILTER{$_[0]} or return }	1346	&{ $FILTER{$_[0]} or return }
		1347	}
		1348
		1349	our %SAFE_FILTER = map { $_ => $FILTER{$_} } 0, 1, 21, 22, 23, 32;
		1350
		1351	sub safe_filter {
		1352	&{ $SAFE_FILTER{$_[0]} or return }
946	}	1353	}
947		1354
948	sub URI::TO_CBOR {	1355	sub URI::TO_CBOR {
949	my $uri = $_[0]->as_string;	1356	my $uri = $_[0]->as_string;
950	utf8::upgrade $uri;	1357	utf8::upgrade $uri;
951	CBOR::XS::tag 32, $uri	1358	tag 32, $uri
952	}	1359	}
953		1360
954	sub Math::BigInt::TO_CBOR {	1361	sub Math::BigInt::TO_CBOR {
955	if ($_[0] >= -2147483648 && $_[0] <= 2147483647) {	1362	if (-2147483648 <= $_[0] && $_[0] <= 2147483647) {
956	$_[0]->numify	1363	$_[0]->numify
957	} else {	1364	} else {
958	my $hex = substr $_[0]->as_hex, 2;	1365	my $hex = substr $_[0]->as_hex, 2;
959	$hex = "0$hex" if 1 & length $hex; # sigh	1366	$hex = "0$hex" if 1 & length $hex; # sigh
960	CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex	1367	tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
961	}	1368	}
962	}	1369	}
963		1370
964	sub Math::BigFloat::TO_CBOR {	1371	sub Math::BigFloat::TO_CBOR {
965	my ($m, $e) = $_[0]->parts;	1372	my ($m, $e) = $_[0]->parts;
		1373
		1374	-9223372036854775808 <= $e && $e <= 18446744073709551615
966	CBOR::XS::tag 4, [$e->numify, $m]	1375	? tag 4, [$e->numify, $m]
		1376	: tag 264, [$e, $m]
		1377	}
		1378
		1379	sub Math::BigRat::TO_CBOR {
		1380	my ($n, $d) = $_[0]->parts;
		1381
		1382	# older versions of BigRat need *1, as they not always return numbers
		1383
		1384	$d*1 == 1
		1385	? $n*1
		1386	: tag 30, [$n1, $d1]
		1387	}
		1388
		1389	sub Time::Piece::TO_CBOR {
		1390	tag 1, 0 + $_[0]->epoch
967	}	1391	}
968		1392
969	XSLoader::load "CBOR::XS", $VERSION;	1393	XSLoader::load "CBOR::XS", $VERSION;
970		1394
971	=head1 SEE ALSO	1395	=head1 SEE ALSO

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Comparing CBOR-XS/XS.pm (file contents): Revision 1.27 by root, Thu Nov 28 15:43:24 2013 UTC vs. Revision 1.70 by root, Sat Nov 9 07:30:36 2019 UTC

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Comparing CBOR-XS/XS.pm (file contents):
Revision 1.27 by root, Thu Nov 28 15:43:24 2013 UTC vs.
Revision 1.70 by root, Sat Nov 9 07:30:36 2019 UTC