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

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.14 by root, Tue Oct 29 20:59:16 2013 UTC vs.
Revision 1.69 by root, Sat Nov 9 07:23:31 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 to
32	you to do). Furthermore, details of the implementation might change freely
33	before version 1.0. And lastly, the object serialisation protocol depends
34	on a pending IANA assignment, and until that assignment is official, this
35	implementation is not interoperable with other implementations (even
36	future versions of this 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
50		41	formats first).
51	To give you a general idea, with texts in the megabyte range, C<CBOR::XS>
52	usually encodes roughly twice as fast as L<Storable> or L<JSON::XS> and
53	decodes about 15%-30% faster than those. The shorter the data, the worse
54	L<Storable> performs in comparison.
55		42
56	The primary goal of this module is to be I<correct> and the secondary goal	43	The primary goal of this module is to be I<correct> and the secondary goal
57	is to be I<fast>. To reach the latter goal it was written in C.	44	is to be I<fast>. To reach the latter goal it was written in C.
58		45
		46	To give you a general idea about speed, with texts in the megabyte range,
		47	C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or
		48	L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the
		49	data, the worse L<Storable> performs in comparison.
		50
		51	Regarding compactness, C<CBOR::XS>-encoded data structures are usually
		52	about 20% smaller than the same data encoded as (compact) JSON or
		53	L<Storable>.
		54
		55	In addition to the core CBOR data format, this module implements a
		56	number of extensions, to support cyclic and shared data structures
		57	(see C<allow_sharing> and C<allow_cycles>), string deduplication (see
		58	C<pack_strings>) and scalar references (always enabled).
		59
59	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
60	vice versa.	61	vice versa.
61		62
62	=cut	63	=cut
63		64
64	package CBOR::XS;	65	package CBOR::XS;
65		66
66	use common::sense;	67	use common::sense;
67		68
68	our $VERSION = 0.06;	69	our $VERSION = 1.71;
69	our @ISA = qw(Exporter);	70	our @ISA = qw(Exporter);
70		71
71	our @EXPORT = qw(encode_cbor decode_cbor);	72	our @EXPORT = qw(encode_cbor decode_cbor);
72		73
73	use Exporter;	74	use Exporter;
…		…
110	strings. All boolean flags described below are by default I<disabled>.	111	strings. All boolean flags described below are by default I<disabled>.
111		112
112	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
113	be chained:	114	be chained:
114		115
115	#TODO
116	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	}
117		142
118	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])	143	=item $cbor = $cbor->max_depth ([$maximum_nesting_depth])
119		144
120	=item $max_depth = $cbor->get_max_depth	145	=item $max_depth = $cbor->get_max_depth
121		146
…		…
137		162
138	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
139	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
140	crashing.	165	crashing.
141		166
142	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.
143		168
144	=item $cbor = $cbor->max_size ([$maximum_string_size])	169	=item $cbor = $cbor->max_size ([$maximum_string_size])
145		170
146	=item $max_size = $cbor->get_max_size	171	=item $max_size = $cbor->get_max_size
147		172
…		…
152	effect on C<encode> (yet).	177	effect on C<encode> (yet).
153		178
154	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
155	C<0> is specified).	180	C<0> is specified).
156		181
157	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.
		183
		184	=item $cbor = $cbor->allow_unknown ([$enable])
		185
		186	=item $enabled = $cbor->get_allow_unknown
		187
		188	If C<$enable> is true (or missing), then C<encode> will I<not> throw an
		189	exception when it encounters values it cannot represent in CBOR (for
		190	example, filehandles) but instead will encode a CBOR C<error> value.
		191
		192	If C<$enable> is false (the default), then C<encode> will throw an
		193	exception when it encounters anything it cannot encode as CBOR.
		194
		195	This option does not affect C<decode> in any way, and it is recommended to
		196	leave it off unless you know your communications partner.
		197
		198	=item $cbor = $cbor->allow_sharing ([$enable])
		199
		200	=item $enabled = $cbor->get_allow_sharing
		201
		202	If C<$enable> is true (or missing), then C<encode> will not double-encode
		203	values that have been referenced before (e.g. when the same object, such
		204	as an array, is referenced multiple times), but instead will emit a
		205	reference to the earlier value.
		206
		207	This means that such values will only be encoded once, and will not result
		208	in a deep cloning of the value on decode, in decoders supporting the value
		209	sharing extension. This also makes it possible to encode cyclic data
		210	structures (which need C<allow_cycles> to be enabled to be decoded by this
		211	module).
		212
		213	It is recommended to leave it off unless you know your
		214	communication partner supports the value sharing extensions to CBOR
		215	(L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the
		216	resulting data structure might be unusable.
		217
		218	Detecting shared values incurs a runtime overhead when values are encoded
		219	that have a reference counter large than one, and might unnecessarily
		220	increase the encoded size, as potentially shared values are encoded as
		221	shareable whether or not they are actually shared.
		222
		223	At the moment, only targets of references can be shared (e.g. scalars,
		224	arrays or hashes pointed to by a reference). Weirder constructs, such as
		225	an array with multiple "copies" of the I<same> string, which are hard but
		226	not impossible to create in Perl, are not supported (this is the same as
		227	with L<Storable>).
		228
		229	If C<$enable> is false (the default), then C<encode> will encode shared
		230	data structures repeatedly, unsharing them in the process. Cyclic data
		231	structures cannot be encoded in this mode.
		232
		233	This option does not affect C<decode> in any way - shared values and
		234	references will always be decoded properly if present.
		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
		275	=item $cbor = $cbor->pack_strings ([$enable])
		276
		277	=item $enabled = $cbor->get_pack_strings
		278
		279	If C<$enable> is true (or missing), then C<encode> will try not to encode
		280	the same string twice, but will instead encode a reference to the string
		281	instead. Depending on your data format, this can save a lot of space, but
		282	also results in a very large runtime overhead (expect encoding times to be
		283	2-4 times as high as without).
		284
		285	It is recommended to leave it off unless you know your
		286	communications partner supports the stringref extension to CBOR
		287	(L<http://cbor.schmorp.de/stringref>), as without decoder support, the
		288	resulting data structure might not be usable.
		289
		290	If C<$enable> is false (the default), then C<encode> will encode strings
		291	the standard CBOR way.
		292
		293	This option does not affect C<decode> in any way - string references will
		294	always be decoded properly if present.
		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
		365	=item $cbor = $cbor->filter ([$cb->($tag, $value)])
		366
		367	=item $cb_or_undef = $cbor->get_filter
		368
		369	Sets or replaces the tagged value decoding filter (when C<$cb> is
		370	specified) or clears the filter (if no argument or C<undef> is provided).
		371
		372	The filter callback is called only during decoding, when a non-enforced
		373	tagged value has been decoded (see L<TAG HANDLING AND EXTENSIONS> for a
		374	list of enforced tags). For specific tags, it's often better to provide a
		375	default converter using the C<%CBOR::XS::FILTER> hash (see below).
		376
		377	The first argument is the numerical tag, the second is the (decoded) value
		378	that has been tagged.
		379
		380	The filter function should return either exactly one value, which will
		381	replace the tagged value in the decoded data structure, or no values,
		382	which will result in default handling, which currently means the decoder
		383	creates a C<CBOR::XS::Tagged> object to hold the tag and the value.
		384
		385	When the filter is cleared (the default state), the default filter
		386	function, C<CBOR::XS::default_filter>, is used. This function simply
		387	looks up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists
		388	it must be a code reference that is called with tag and value, and is
		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.
		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
		404	Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
		405	objects, with no other special handling (useful when working with
		406	potentially "unsafe" CBOR data).
		407
		408	CBOR::XS->new->filter (sub { })->decode ($cbor_data);
		409
		410	Example: provide a global filter for tag 1347375694, converting the value
		411	into some string form.
		412
		413	$CBOR::XS::FILTER{1347375694} = sub {
		414	my ($tag, $value);
		415
		416	"tag 1347375694 value $value"
		417	};
		418
		419	Example: provide your own filter function that looks up tags in your own
		420	hash:
		421
		422	my %my_filter = (
		423	998347484 => sub {
		424	my ($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);
158		439
159	=item $cbor_data = $cbor->encode ($perl_scalar)	440	=item $cbor_data = $cbor->encode ($perl_scalar)
160		441
161	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
162	representation.	443	representation.
…		…
176	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
177	starts.	458	starts.
178		459
179	CBOR::XS->new->decode_prefix ("......")	460	CBOR::XS->new->decode_prefix ("......")
180	=> ("...", 3)	461	=> ("...", 3)
		462
		463	=back
		464
		465	=head2 INCREMENTAL PARSING
		466
		467	In some cases, there is the need for incremental parsing of JSON
		468	texts. While this module always has to keep both CBOR text and resulting
		469	Perl data structure in memory at one time, it does allow you to parse a
		470	CBOR stream incrementally, using a similar to using "decode_prefix" to see
		471	if a full CBOR object is available, but is much more efficient.
		472
		473	It basically works by parsing as much of a CBOR string as possible - if
		474	the CBOR data is not complete yet, the pasrer will remember where it was,
		475	to be able to restart when more data has been accumulated. Once enough
		476	data is available to either decode a complete CBOR value or raise an
		477	error, a real decode will be attempted.
		478
		479	A typical use case would be a network protocol that consists of sending
		480	and receiving CBOR-encoded messages. The solution that works with CBOR and
		481	about anything else is by prepending a length to every CBOR value, so the
		482	receiver knows how many octets to read. More compact (and slightly slower)
		483	would be to just send CBOR values back-to-back, as C<CBOR::XS> knows where
		484	a CBOR value ends, and doesn't need an explicit length.
		485
		486	The following methods help with this:
		487
		488	=over 4
		489
		490	=item @decoded = $cbor->incr_parse ($buffer)
		491
		492	This method attempts to decode exactly one CBOR value from the beginning
		493	of the given C<$buffer>. The value is removed from the C<$buffer> on
		494	success. When C<$buffer> doesn't contain a complete value yet, it returns
		495	nothing. Finally, when the C<$buffer> doesn't start with something
		496	that could ever be a valid CBOR value, it raises an exception, just as
		497	C<decode> would. In the latter case the decoder state is undefined and
		498	must be reset before being able to parse further.
		499
		500	This method modifies the C<$buffer> in place. When no CBOR value can be
		501	decoded, the decoder stores the current string offset. On the next call,
		502	continues decoding at the place where it stopped before. For this to make
		503	sense, the C<$buffer> must begin with the same octets as on previous
		504	unsuccessful calls.
		505
		506	You can call this method in scalar context, in which case it either
		507	returns a decoded value or C<undef>. This makes it impossible to
		508	distinguish between CBOR null values (which decode to C<undef>) and an
		509	unsuccessful decode, which is often acceptable.
		510
		511	=item @decoded = $cbor->incr_parse_multiple ($buffer)
		512
		513	Same as C<incr_parse>, but attempts to decode as many CBOR values as
		514	possible in one go, instead of at most one. Calls to C<incr_parse> and
		515	C<incr_parse_multiple> can be interleaved.
		516
		517	=item $cbor->incr_reset
		518
		519	Resets the incremental decoder. This throws away any saved state, so that
		520	subsequent calls to C<incr_parse> or C<incr_parse_multiple> start to parse
		521	a new CBOR value from the beginning of the C<$buffer> again.
		522
		523	This method can be called at any time, but it I<must> be called if you want
		524	to change your C<$buffer> or there was a decoding error and you want to
		525	reuse the C<$cbor> object for future incremental parsings.
181		526
182	=back	527	=back
183		528
184		529
185	=head1 MAPPING	530	=head1 MAPPING
…		…
203	CBOR integers become (numeric) perl scalars. On perls without 64 bit	548	CBOR integers become (numeric) perl scalars. On perls without 64 bit
204	support, 64 bit integers will be truncated or otherwise corrupted.	549	support, 64 bit integers will be truncated or otherwise corrupted.
205		550
206	=item byte strings	551	=item byte strings
207		552
208	Byte strings will become octet strings in Perl (the byte values 0..255	553	Byte strings will become octet strings in Perl (the Byte values 0..255
209	will simply become characters of the same value in Perl).	554	will simply become characters of the same value in Perl).
210		555
211	=item UTF-8 strings	556	=item UTF-8 strings
212		557
213	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be	558	UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be
…		…
231	C<Types:Serialiser::false> and C<Types::Serialiser::error>,	576	C<Types:Serialiser::false> and C<Types::Serialiser::error>,
232	respectively. They are overloaded to act almost exactly like the numbers	577	respectively. They are overloaded to act almost exactly like the numbers
233	C<1> and C<0> (for true and false) or to throw an exception on access (for	578	C<1> and C<0> (for true and false) or to throw an exception on access (for
234	error). See the L<Types::Serialiser> manpage for details.	579	error). See the L<Types::Serialiser> manpage for details.
235		580
236	=item CBOR tag 256 (perl object)	581	=item tagged values
237		582
238	The tag value C<256> (TODO: pending iana registration) will be used
239	to deserialise a Perl object serialised with C<FREEZE>. See L<OBJECT
240	SERIALISATION>, below, for details.
241
242	=item CBOR tag 55799 (magic header)
243
244	The tag 55799 is ignored (this tag implements the magic header).
245
246	=item other CBOR tags
247
248	Tagged items consists of a numeric tag and another CBOR value. Tags not	583	Tagged items consists of a numeric tag and another CBOR value.
249	handled internally are currently converted into a L<CBOR::XS::Tagged>
250	object, which is simply a blessed array reference consisting of the
251	numeric tag value followed by the (decoded) CBOR value.
252		584
253	In the future, support for user-supplied conversions might get added.	585	See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >>
		586	for details on which tags are handled how.
254		587
255	=item anything else	588	=item anything else
256		589
257	Anything else (e.g. unsupported simple values) will raise a decoding	590	Anything else (e.g. unsupported simple values) will raise a decoding
258	error.	591	error.
…		…
261		594
262		595
263	=head2 PERL -> CBOR	596	=head2 PERL -> CBOR
264		597
265	The mapping from Perl to CBOR is slightly more difficult, as Perl is a	598	The mapping from Perl to CBOR is slightly more difficult, as Perl is a
266	truly typeless language, so we can only guess which CBOR type is meant by	599	typeless language. That means this module can only guess which CBOR type
267	a Perl value.	600	is meant by a perl value.
268		601
269	=over 4	602	=over 4
270		603
271	=item hash references	604	=item hash references
272		605
273	Perl hash references become CBOR maps. As there is no inherent ordering in	606	Perl hash references become CBOR maps. As there is no inherent ordering in
274	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random	607	hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
275	order.	608	order. This order can be different each time a hash is encoded.
276		609
277	Currently, tied hashes will use the indefinite-length format, while normal	610	Currently, tied hashes will use the indefinite-length format, while normal
278	hashes will use the fixed-length format.	611	hashes will use the fixed-length format.
279		612
280	=item array references	613	=item array references
281		614
282	Perl array references become fixed-length CBOR arrays.	615	Perl array references become fixed-length CBOR arrays.
283		616
284	=item other references	617	=item other references
285		618
286	Other unblessed references are generally not allowed and will cause an	619	Other unblessed references will be represented using
287	exception to be thrown, except for references to the integers C<0> and	620	the indirection tag extension (tag value C<22098>,
288	C<1>, which get turned into false and true in CBOR.	621	L<http://cbor.schmorp.de/indirection>). CBOR decoders are guaranteed
		622	to be able to decode these values somehow, by either "doing the right
		623	thing", decoding into a generic tagged object, simply ignoring the tag, or
		624	something else.
289		625
290	=item CBOR::XS::Tagged objects	626	=item CBOR::XS::Tagged objects
291		627
292	Objects of this type must be arrays consisting of a single C<[tag, value]>	628	Objects of this type must be arrays consisting of a single C<[tag, value]>
293	pair. The (numerical) tag will be encoded as a CBOR tag, the value will	629	pair. The (numerical) tag will be encoded as a CBOR tag, the value will
294	be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to	630	be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to
295	create such objects.	631	create such objects.
296		632
297	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error	633	=item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error
298		634
299	These special values become CBOR true, CBOR false and CBOR undefined	635	These special values become CBOR true, CBOR false and CBOR undefined
…		…
301	if you want.	637	if you want.
302		638
303	=item other blessed objects	639	=item other blessed objects
304		640
305	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See	641	Other blessed objects are serialised via C<TO_CBOR> or C<FREEZE>. See
306	L<OBJECT SERIALISATION>, below, for details.	642	L<TAG HANDLING AND EXTENSIONS> for specific classes handled by this
		643	module, and L<OBJECT SERIALISATION> for generic object serialisation.
307		644
308	=item simple scalars	645	=item simple scalars
309		646
310	TODO
311	Simple Perl scalars (any scalar that is not a reference) are the most	647	Simple Perl scalars (any scalar that is not a reference) are the most
312	difficult objects to encode: CBOR::XS will encode undefined scalars as	648	difficult objects to encode: CBOR::XS will encode undefined scalars as
313	CBOR null values, scalars that have last been used in a string context	649	CBOR null values, scalars that have last been used in a string context
314	before encoding as CBOR strings, and anything else as number value:	650	before encoding as CBOR strings, and anything else as number value:
315		651
316	# dump as number	652	# dump as number
317	encode_cbor [2] # yields [2]	653	encode_cbor [2] # yields [2]
318	encode_cbor [-3.0e17] # yields [-3e+17]	654	encode_cbor [-3.0e17] # yields [-3e+17]
319	my $value = 5; encode_cbor [$value] # yields [5]	655	my $value = 5; encode_cbor [$value] # yields [5]
320		656
321	# used as string, so dump as string	657	# used as string, so dump as string (either byte or text)
322	print $value;	658	print $value;
323	encode_cbor [$value] # yields ["5"]	659	encode_cbor [$value] # yields ["5"]
324		660
325	# undef becomes null	661	# undef becomes null
326	encode_cbor [undef] # yields [null]	662	encode_cbor [undef] # yields [null]
…		…
329		665
330	my $x = 3.1; # some variable containing a number	666	my $x = 3.1; # some variable containing a number
331	"$x"; # stringified	667	"$x"; # stringified
332	$x .= ""; # another, more awkward way to stringify	668	$x .= ""; # another, more awkward way to stringify
333	print $x; # perl does it for you, too, quite often	669	print $x; # perl does it for you, too, quite often
		670
		671	You can force whether a string is encoded as byte or text string by using
		672	C<utf8::upgrade> and C<utf8::downgrade> (if C<text_strings> is disabled):
		673
		674	utf8::upgrade $x; # encode $x as text string
		675	utf8::downgrade $x; # encode $x as byte string
		676
		677	Perl doesn't define what operations up- and downgrade strings, so if the
		678	difference between byte and text is important, you should up- or downgrade
		679	your string as late as possible before encoding. You can also force the
		680	use of CBOR text strings by using C<text_keys> or C<text_strings>.
334		681
335	You can force the type to be a CBOR number by numifying it:	682	You can force the type to be a CBOR number by numifying it:
336		683
337	my $x = "3"; # some variable containing a string	684	my $x = "3"; # some variable containing a string
338	$x += 0; # numify it, ensuring it will be dumped as a number	685	$x += 0; # numify it, ensuring it will be dumped as a number
…		…
351		698
352	=back	699	=back
353		700
354	=head2 OBJECT SERIALISATION	701	=head2 OBJECT SERIALISATION
355		702
		703	This module implements both a CBOR-specific and the generic
		704	L<Types::Serialier> object serialisation protocol. The following
		705	subsections explain both methods.
		706
		707	=head3 ENCODING
		708
356	This module knows two way to serialise a Perl object: The CBOR-specific	709	This module knows two way to serialise a Perl object: The CBOR-specific
357	way, and the generic way.	710	way, and the generic way.
358		711
359	Whenever the encoder encounters a Perl object that it cnanot serialise	712	Whenever the encoder encounters a Perl object that it cannot serialise
360	directly (most of them), it will first look up the C<TO_CBOR> method on	713	directly (most of them), it will first look up the C<TO_CBOR> method on
361	it.	714	it.
362		715
363	If it has a C<TO_CBOR> method, it will call it with the object as only	716	If it has a C<TO_CBOR> method, it will call it with the object as only
364	argument, and expects exactly one return value, which it will then	717	argument, and expects exactly one return value, which it will then
…		…
370		723
371	The C<FREEZE> method can return any number of values (i.e. zero or	724	The C<FREEZE> method can return any number of values (i.e. zero or
372	more). These will be encoded as CBOR perl object, together with the	725	more). These will be encoded as CBOR perl object, together with the
373	classname.	726	classname.
374		727
		728	These methods I<MUST NOT> change the data structure that is being
		729	serialised. Failure to comply to this can result in memory corruption -
		730	and worse.
		731
375	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail	732	If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
376	with an error.	733	with an error.
377		734
		735	=head3 DECODING
		736
378	Objects encoded via C<TO_CBOR> cannot be automatically decoded, but	737	Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
379	objects encoded via C<FREEZE> can be decoded using the following protocol:	738	but objects encoded via C<FREEZE> can be decoded using the following
		739	protocol:
380		740
381	When an encoded CBOR perl object is encountered by the decoder, it will	741	When an encoded CBOR perl object is encountered by the decoder, it will
382	look up the C<THAW> method, by using the stored classname, and will fail	742	look up the C<THAW> method, by using the stored classname, and will fail
383	if the method cannot be found.	743	if the method cannot be found.
384		744
385	After the lookup it will call the C<THAW> method with the stored classname	745	After the lookup it will call the C<THAW> method with the stored classname
386	as first argument, the constant string C<CBOR> as second argument, and all	746	as first argument, the constant string C<CBOR> as second argument, and all
387	values returned by C<FREEZE> as remaining arguments.	747	values returned by C<FREEZE> as remaining arguments.
388		748
389	=head4 EXAMPLES	749	=head3 EXAMPLES
390		750
391	Here is an example C<TO_CBOR> method:	751	Here is an example C<TO_CBOR> method:
392		752
393	sub My::Object::TO_CBOR {	753	sub My::Object::TO_CBOR {
394	my ($obj) = @_;	754	my ($obj) = @_;
…		…
405		765
406	sub URI::TO_CBOR {	766	sub URI::TO_CBOR {
407	my ($self) = @_;	767	my ($self) = @_;
408	my $uri = "$self"; # stringify uri	768	my $uri = "$self"; # stringify uri
409	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string	769	utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string
410	CBOR::XS::tagged 32, "$_[0]"	770	CBOR::XS::tag 32, "$_[0]"
411	}	771	}
412		772
413	This will encode URIs as a UTF-8 string with tag 32, which indicates an	773	This will encode URIs as a UTF-8 string with tag 32, which indicates an
414	URI.	774	URI.
415		775
…		…
426	"$self" # encode url string	786	"$self" # encode url string
427	}	787	}
428		788
429	sub URI::THAW {	789	sub URI::THAW {
430	my ($class, $serialiser, $uri) = @_;	790	my ($class, $serialiser, $uri) = @_;
431
432	$class->new ($uri)	791	$class->new ($uri)
433	}	792	}
434		793
435	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For	794	Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
436	example, a C<FREEZE> method that returns "type", "id" and "variant" values	795	example, a C<FREEZE> method that returns "type", "id" and "variant" values
…		…
452	=head1 MAGIC HEADER	811	=head1 MAGIC HEADER
453		812
454	There is no way to distinguish CBOR from other formats	813	There is no way to distinguish CBOR from other formats
455	programmatically. To make it easier to distinguish CBOR from other	814	programmatically. To make it easier to distinguish CBOR from other
456	formats, the CBOR specification has a special "magic string" that can be	815	formats, the CBOR specification has a special "magic string" that can be
457	prepended to any CBOR string without changing it's meaning.	816	prepended to any CBOR string without changing its meaning.
458		817
459	This string is available as C<$CBOR::XS::MAGIC>. This module does not	818	This string is available as C<$CBOR::XS::MAGIC>. This module does not
460	prepend this string tot he CBOR data it generates, but it will ignroe it	819	prepend this string to the CBOR data it generates, but it will ignore it
461	if present, so users can prepend this string as a "file type" indicator as	820	if present, so users can prepend this string as a "file type" indicator as
462	required.	821	required.
463		822
464		823
465	=head1 THE CBOR::XS::Tagged CLASS	824	=head1 THE CBOR::XS::Tagged CLASS
…		…
548	Wrap CBOR data in CBOR:	907	Wrap CBOR data in CBOR:
549		908
550	my $cbor_cbor = encode_cbor	909	my $cbor_cbor = encode_cbor
551	CBOR::XS::tag 24,	910	CBOR::XS::tag 24,
552	encode_cbor [1, 2, 3];	911	encode_cbor [1, 2, 3];
		912
		913	=head1 TAG HANDLING AND EXTENSIONS
		914
		915	This section describes how this module handles specific tagged values
		916	and extensions. If a tag is not mentioned here and no additional filters
		917	are provided for it, then the default handling applies (creating a
		918	CBOR::XS::Tagged object on decoding, and only encoding the tag when
		919	explicitly requested).
		920
		921	Tags not handled specifically are currently converted into a
		922	L<CBOR::XS::Tagged> object, which is simply a blessed array reference
		923	consisting of the numeric tag value followed by the (decoded) CBOR value.
		924
		925	Future versions of this module reserve the right to special case
		926	additional tags (such as base64url).
		927
		928	=head2 ENFORCED TAGS
		929
		930	These tags are always handled when decoding, and their handling cannot be
		931	overridden by the user.
		932
		933	=over 4
		934
		935	=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
		936
		937	These tags are automatically created (and decoded) for serialisable
		938	objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
		939	serialisation protocol). See L<OBJECT SERIALISATION> for details.
		940
		941	=item 28, 29 (shareable, sharedref, L<http://cbor.schmorp.de/value-sharing>)
		942
		943	These tags are automatically decoded when encountered (and they do not
		944	result in a cyclic data structure, see C<allow_cycles>), resulting in
		945	shared values in the decoded object. They are only encoded, however, when
		946	C<allow_sharing> is enabled.
		947
		948	Not all shared values can be successfully decoded: values that reference
		949	themselves will I<currently> decode as C<undef> (this is not the same
		950	as a reference pointing to itself, which will be represented as a value
		951	that contains an indirect reference to itself - these will be decoded
		952	properly).
		953
		954	Note that considerably more shared value data structures can be decoded
		955	than will be encoded - currently, only values pointed to by references
		956	will be shared, others will not. While non-reference shared values can be
		957	generated in Perl with some effort, they were considered too unimportant
		958	to be supported in the encoder. The decoder, however, will decode these
		959	values as shared values.
		960
		961	=item 256, 25 (stringref-namespace, stringref, L<http://cbor.schmorp.de/stringref>)
		962
		963	These tags are automatically decoded when encountered. They are only
		964	encoded, however, when C<pack_strings> is enabled.
		965
		966	=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
		967
		968	This tag is automatically generated when a reference are encountered (with
		969	the exception of hash and array references). It is converted to a reference
		970	when decoding.
		971
		972	=item 55799 (self-describe CBOR, RFC 7049)
		973
		974	This value is not generated on encoding (unless explicitly requested by
		975	the user), and is simply ignored when decoding.
		976
		977	=back
		978
		979	=head2 NON-ENFORCED TAGS
		980
		981	These tags have default filters provided when decoding. Their handling can
		982	be overridden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
		983	providing a custom C<filter> callback when decoding.
		984
		985	When they result in decoding into a specific Perl class, the module
		986	usually provides a corresponding C<TO_CBOR> method as well.
		987
		988	When any of these need to load additional modules that are not part of the
		989	perl core distribution (e.g. L<URI>), it is (currently) up to the user to
		990	provide these modules. The decoding usually fails with an exception if the
		991	required module cannot be loaded.
		992
		993	=over 4
		994
		995	=item 0, 1 (date/time string, seconds since the epoch)
		996
		997	These tags are decoded into L<Time::Piece> objects. The corresponding
		998	C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently.
		999
		1000	The L<Time::Piece> API is generally surprisingly bad, and fractional
		1001	seconds are only accidentally kept intact, so watch out. On the plus side,
		1002	the module comes with perl since 5.10, which has to count for something.
		1003
		1004	=item 2, 3 (positive/negative bignum)
		1005
		1006	These tags are decoded into L<Math::BigInt> objects. The corresponding
		1007	C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
		1008	integers, and others into positive/negative CBOR bignums.
		1009
		1010	=item 4, 5, 264, 265 (decimal fraction/bigfloat)
		1011
		1012	Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>
		1013	objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>
		1014	encodes into a decimal fraction (either tag 4 or 264).
		1015
		1016	NaN and infinities are not encoded properly, as they cannot be represented
		1017	in CBOR.
		1018
		1019	See L<BIGNUM SECURITY CONSIDERATIONS> for more info.
		1020
		1021	=item 30 (rational numbers)
		1022
		1023	These tags are decoded into L<Math::BigRat> objects. The corresponding
		1024	C<Math::BigRat::TO_CBOR> method encodes rational numbers with denominator
		1025	C<1> via their numerator only, i.e., they become normal integers or
		1026	C<bignums>.
		1027
		1028	See L<BIGNUM SECURITY CONSIDERATIONS> for more info.
		1029
		1030	=item 21, 22, 23 (expected later JSON conversion)
		1031
		1032	CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these
		1033	tags.
		1034
		1035	=item 32 (URI)
		1036
		1037	These objects decode into L<URI> objects. The corresponding
		1038	C<URI::TO_CBOR> method again results in a CBOR URI value.
		1039
		1040	=back
		1041
		1042	=cut
553		1043
554	=head1 CBOR and JSON	1044	=head1 CBOR and JSON
555		1045
556	CBOR is supposed to implement a superset of the JSON data model, and is,	1046	CBOR is supposed to implement a superset of the JSON data model, and is,
557	with some coercion, able to represent all JSON texts (something that other	1047	with some coercion, able to represent all JSON texts (something that other
…		…
566	CBOR intact.	1056	CBOR intact.
567		1057
568		1058
569	=head1 SECURITY CONSIDERATIONS	1059	=head1 SECURITY CONSIDERATIONS
570		1060
571	When you are using CBOR in a protocol, talking to untrusted potentially	1061	Tl;dr... if you want to decode or encode CBOR from untrusted sources, you
572	hostile creatures requires relatively few measures.	1062	should start with a coder object created via C<new_safe> (which implements
		1063	the mitigations explained below):
573		1064
		1065	my $coder = CBOR::XS->new_safe;
		1066
		1067	my $data = $coder->decode ($cbor_text);
		1068	my $cbor = $coder->encode ($data);
		1069
		1070	Longer version: When you are using CBOR in a protocol, talking to
		1071	untrusted potentially hostile creatures requires some thought:
		1072
		1073	=over 4
		1074
		1075	=item Security of the CBOR decoder itself
		1076
574	First of all, your CBOR decoder should be secure, that is, should not have	1077	First and foremost, your CBOR decoder should be secure, that is, should
		1078	not have any buffer overflows or similar bugs that could potentially be
575	any buffer overflows. Obviously, this module should ensure that and I am	1079	exploited. Obviously, this module should ensure that and I am trying hard
576	trying hard on making that true, but you never know.	1080	on making that true, but you never know.
577		1081
		1082	=item CBOR::XS can invoke almost arbitrary callbacks during decoding
		1083
		1084	CBOR::XS supports object serialisation - decoding CBOR can cause calls
		1085	to I<any> C<THAW> method in I<any> package that exists in your process
		1086	(that is, CBOR::XS will not try to load modules, but any existing C<THAW>
		1087	method or function can be called, so they all have to be secure).
		1088
		1089	Less obviously, it will also invoke C<TO_CBOR> and C<FREEZE> methods -
		1090	even if all your C<THAW> methods are secure, encoding data structures from
		1091	untrusted sources can invoke those and trigger bugs in those.
		1092
		1093	So, if you are not sure about the security of all the modules you
		1094	have loaded (you shouldn't), you should disable this part using
		1095	C<forbid_objects> or using C<new_safe>.
		1096
		1097	=item CBOR can be extended with tags that call library code
		1098
		1099	CBOR can be extended with tags, and C<CBOR::XS> has a registry of
		1100	conversion functions for many existing tags that can be extended via
		1101	third-party modules (see the C<filter> method).
		1102
		1103	If you don't trust these, you should configure the "safe" filter function,
		1104	C<CBOR::XS::safe_filter> (C<new_safe> does this), which by default only
		1105	includes conversion functions that are considered "safe" by the author
		1106	(but again, they can be extended by third party modules).
		1107
		1108	Depending on your level of paranoia, you can use the "safe" filter:
		1109
		1110	$cbor->filter (\&CBOR::XS::safe_filter);
		1111
		1112	... your own filter...
		1113
		1114	$cbor->filter (sub { ... do your stuffs here ... });
		1115
		1116	... or even no filter at all, disabling all tag decoding:
		1117
		1118	$cbor->filter (sub { });
		1119
		1120	This is never a problem for encoding, as the tag mechanism only exists in
		1121	CBOR texts.
		1122
		1123	=item Resource-starving attacks: object memory usage
		1124
578	Second, you need to avoid resource-starving attacks. That means you should	1125	You need to avoid resource-starving attacks. That means you should limit
579	limit the size of CBOR data you accept, or make sure then when your	1126	the size of CBOR data you accept, or make sure then when your resources
580	resources run out, that's just fine (e.g. by using a separate process that	1127	run out, that's just fine (e.g. by using a separate process that can
581	can crash safely). The size of a CBOR string in octets is usually a good	1128	crash safely). The size of a CBOR string in octets is usually a good
582	indication of the size of the resources required to decode it into a Perl	1129	indication of the size of the resources required to decode it into a Perl
583	structure. While CBOR::XS can check the size of the CBOR text, it might be	1130	structure. While CBOR::XS can check the size of the CBOR text (using
584	too late when you already have it in memory, so you might want to check	1131	C<max_size> - done by C<new_safe>), it might be too late when you already
585	the size before you accept the string.	1132	have it in memory, so you might want to check the size before you accept
		1133	the string.
586		1134
		1135	As for encoding, it is possible to construct data structures that are
		1136	relatively small but result in large CBOR texts (for example by having an
		1137	array full of references to the same big data structure, which will all be
		1138	deep-cloned during encoding by default). This is rarely an actual issue
		1139	(and the worst case is still just running out of memory), but you can
		1140	reduce this risk by using C<allow_sharing>.
		1141
		1142	=item Resource-starving attacks: stack overflows
		1143
587	Third, CBOR::XS recurses using the C stack when decoding objects and	1144	CBOR::XS recurses using the C stack when decoding objects and arrays. The
588	arrays. The C stack is a limited resource: for instance, on my amd64	1145	C stack is a limited resource: for instance, on my amd64 machine with 8MB
589	machine with 8MB of stack size I can decode around 180k nested arrays but	1146	of stack size I can decode around 180k nested arrays but only 14k nested
590	only 14k nested CBOR objects (due to perl itself recursing deeply on croak	1147	CBOR objects (due to perl itself recursing deeply on croak to free the
591	to free the temporary). If that is exceeded, the program crashes. To be	1148	temporary). If that is exceeded, the program crashes. To be conservative,
592	conservative, the default nesting limit is set to 512. If your process	1149	the default nesting limit is set to 512. If your process has a smaller
593	has a smaller stack, you should adjust this setting accordingly with the	1150	stack, you should adjust this setting accordingly with the C<max_depth>
594	C<max_depth> method.	1151	method.
		1152
		1153	=item Resource-starving attacks: CPU en-/decoding complexity
		1154
		1155	CBOR::XS will use the L<Math::BigInt>, L<Math::BigFloat> and
		1156	L<Math::BigRat> libraries to represent encode/decode bignums. These can be
		1157	very slow (as in, centuries of CPU time) and can even crash your program
		1158	(and are generally not very trustworthy). See the next section on bignum
		1159	security for details.
		1160
		1161	=item Data breaches: leaking information in error messages
		1162
		1163	CBOR::XS might leak contents of your Perl data structures in its error
		1164	messages, so when you serialise sensitive information you might want to
		1165	make sure that exceptions thrown by CBOR::XS will not end up in front of
		1166	untrusted eyes.
		1167
		1168	=item Something else...
595		1169
596	Something else could bomb you, too, that I forgot to think of. In that	1170	Something else could bomb you, too, that I forgot to think of. In that
597	case, you get to keep the pieces. I am always open for hints, though...	1171	case, you get to keep the pieces. I am always open for hints, though...
598		1172
599	Also keep in mind that CBOR::XS might leak contents of your Perl data	1173	=back
600	structures in its error messages, so when you serialise sensitive	1174
601	information you might want to make sure that exceptions thrown by CBOR::XS	1175
602	will not end up in front of untrusted eyes.	1176	=head1 BIGNUM SECURITY CONSIDERATIONS
		1177
		1178	CBOR::XS provides a C<TO_CBOR> method for both L<Math::BigInt> and
		1179	L<Math::BigFloat> that tries to encode the number in the simplest possible
		1180	way, that is, either a CBOR integer, a CBOR bigint/decimal fraction (tag
		1181	4) or an arbitrary-exponent decimal fraction (tag 264). Rational numbers
		1182	(L<Math::BigRat>, tag 30) can also contain bignums as members.
		1183
		1184	CBOR::XS will also understand base-2 bigfloat or arbitrary-exponent
		1185	bigfloats (tags 5 and 265), but it will never generate these on its own.
		1186
		1187	Using the built-in L<Math::BigInt::Calc> support, encoding and decoding
		1188	decimal fractions is generally fast. Decoding bigints can be slow for very
		1189	big numbers (tens of thousands of digits, something that could potentially
		1190	be caught by limiting the size of CBOR texts), and decoding bigfloats or
		1191	arbitrary-exponent bigfloats can be I<extremely> slow (minutes, decades)
		1192	for large exponents (roughly 40 bit and longer).
		1193
		1194	Additionally, L<Math::BigInt> can take advantage of other bignum
		1195	libraries, such as L<Math::GMP>, which cannot handle big floats with large
		1196	exponents, and might simply abort or crash your program, due to their code
		1197	quality.
		1198
		1199	This can be a concern if you want to parse untrusted CBOR. If it is, you
		1200	might want to disable decoding of tag 2 (bigint) and 3 (negative bigint)
		1201	types. You should also disable types 5 and 265, as these can be slow even
		1202	without bigints.
		1203
		1204	Disabling bigints will also partially or fully disable types that rely on
		1205	them, e.g. rational numbers that use bignums.
		1206
603		1207
604	=head1 CBOR IMPLEMENTATION NOTES	1208	=head1 CBOR IMPLEMENTATION NOTES
605		1209
606	This section contains some random implementation notes. They do not	1210	This section contains some random implementation notes. They do not
607	describe guaranteed behaviour, but merely behaviour as-is implemented	1211	describe guaranteed behaviour, but merely behaviour as-is implemented
…		…
616	Only the double data type is supported for NV data types - when Perl uses	1220	Only the double data type is supported for NV data types - when Perl uses
617	long double to represent floating point values, they might not be encoded	1221	long double to represent floating point values, they might not be encoded
618	properly. Half precision types are accepted, but not encoded.	1222	properly. Half precision types are accepted, but not encoded.
619		1223
620	Strict mode and canonical mode are not implemented.	1224	Strict mode and canonical mode are not implemented.
		1225
		1226
		1227	=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
		1228
		1229	On perls that were built without 64 bit integer support (these are rare
		1230	nowadays, even on 32 bit architectures, as all major Perl distributions
		1231	are built with 64 bit integer support), support for any kind of 64 bit
		1232	integer in CBOR is very limited - most likely, these 64 bit values will
		1233	be truncated, corrupted, or otherwise not decoded correctly. This also
		1234	includes string, array and map sizes that are stored as 64 bit integers.
621		1235
622		1236
623	=head1 THREADS	1237	=head1 THREADS
624		1238
625	This module is I<not> guaranteed to be thread safe and there are no	1239	This module is I<not> guaranteed to be thread safe and there are no
…		…
639	Please refrain from using rt.cpan.org or any other bug reporting	1253	Please refrain from using rt.cpan.org or any other bug reporting
640	service. I put the contact address into my modules for a reason.	1254	service. I put the contact address into my modules for a reason.
641		1255
642	=cut	1256	=cut
643		1257
		1258	# clumsy and slow hv_store-in-hash helper function
		1259	sub _hv_store {
		1260	$_[0]{$_[1]} = $_[2];
		1261	}
		1262
		1263	our %FILTER = (
		1264	0 => sub { # rfc4287 datetime, utf-8
		1265	require Time::Piece;
		1266	# Time::Piece::Strptime uses the "incredibly flexible date parsing routine"
		1267	# from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything
		1268	# else either. Whats incredibe over standard strptime totally escapes me.
		1269	# doesn't do fractional times, either. sigh.
		1270	# In fact, it's all a lie, it uses whatever strptime it wants, and of course,
		1271	# they are all incompatible. The openbsd one simply ignores %z (but according to the
		1272	# docs, it would be much more incredibly flexible indeed. If it worked, that is.).
		1273	scalar eval {
		1274	my $s = $_[1];
		1275
		1276	$s =~ s/Z$/+00:00/;
		1277	$s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$//
		1278	or die;
		1279
		1280	my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully
		1281	my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S");
		1282
		1283	Time::Piece::gmtime ($d->epoch + $b)
		1284	} \|\| die "corrupted CBOR date/time string ($_[0])";
		1285	},
		1286
		1287	1 => sub { # seconds since the epoch, possibly fractional
		1288	require Time::Piece;
		1289	scalar Time::Piece::gmtime (pop)
		1290	},
		1291
		1292	2 => sub { # pos bigint
		1293	require Math::BigInt;
		1294	Math::BigInt->new ("0x" . unpack "H*", pop)
		1295	},
		1296
		1297	3 => sub { # neg bigint
		1298	require Math::BigInt;
		1299	-Math::BigInt->new ("0x" . unpack "H*", pop)
		1300	},
		1301
		1302	4 => sub { # decimal fraction, array
		1303	require Math::BigFloat;
		1304	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		1305	},
		1306
		1307	264 => sub { # decimal fraction with arbitrary exponent
		1308	require Math::BigFloat;
		1309	Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
		1310	},
		1311
		1312	5 => sub { # bigfloat, array
		1313	require Math::BigFloat;
		1314	scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
		1315	},
		1316
		1317	265 => sub { # bigfloat with arbitrary exponent
		1318	require Math::BigFloat;
		1319	scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
		1320	},
		1321
		1322	30 => sub { # rational number
		1323	require Math::BigRat;
		1324	Math::BigRat->new ("$_[1][0]/$_[1][1]") # separate parameters only work in recent versons
		1325	},
		1326
		1327	21 => sub { pop }, # expected conversion to base64url encoding
		1328	22 => sub { pop }, # expected conversion to base64 encoding
		1329	23 => sub { pop }, # expected conversion to base16 encoding
		1330
		1331	# 24 # embedded cbor, byte string
		1332
		1333	32 => sub {
		1334	require URI;
		1335	URI->new (pop)
		1336	},
		1337
		1338	# 33 # base64url rfc4648, utf-8
		1339	# 34 # base64 rfc46484, utf-8
		1340	# 35 # regex pcre/ecma262, utf-8
		1341	# 36 # mime message rfc2045, utf-8
		1342	);
		1343
		1344	sub default_filter {
		1345	&{ $FILTER{$_[0]} or return }
		1346	}
		1347
		1348	our %SAFE_FILTER = map { $_ => $FILTER{$_} } 0, 1, 21, 22, 23, 32;
		1349
		1350	sub safe_filter {
		1351	&{ $SAFE_FILTER{$_[0]} or return }
		1352	}
		1353
		1354	sub URI::TO_CBOR {
		1355	my $uri = $_[0]->as_string;
		1356	utf8::upgrade $uri;
		1357	tag 32, $uri
		1358	}
		1359
		1360	sub Math::BigInt::TO_CBOR {
		1361	if (-2147483648 <= $_[0] && $_[0] <= 2147483647) {
		1362	$_[0]->numify
		1363	} else {
		1364	my $hex = substr $_[0]->as_hex, 2;
		1365	$hex = "0$hex" if 1 & length $hex; # sigh
		1366	tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
		1367	}
		1368	}
		1369
		1370	sub Math::BigFloat::TO_CBOR {
		1371	my ($m, $e) = $_[0]->parts;
		1372
		1373	-9223372036854775808 <= $e && $e <= 18446744073709551615
		1374	? tag 4, [$e->numify, $m]
		1375	: tag 264, [$e, $m]
		1376	}
		1377
		1378	sub Math::BigRat::TO_CBOR {
		1379	my ($n, $d) = $_[0]->parts;
		1380
		1381	# older versions of BigRat need *1, as they not always return numbers
		1382
		1383	$d*1 == 1
		1384	? $n*1
		1385	: tag 30, [$n1, $d1]
		1386	}
		1387
		1388	sub Time::Piece::TO_CBOR {
		1389	tag 1, 0 + $_[0]->epoch
		1390	}
		1391
644	XSLoader::load "CBOR::XS", $VERSION;	1392	XSLoader::load "CBOR::XS", $VERSION;
645		1393
646	=head1 SEE ALSO	1394	=head1 SEE ALSO
647		1395
648	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,	1396	The L<JSON> and L<JSON::XS> modules that do similar, but human-readable,

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Comparing CBOR-XS/XS.pm (file contents): Revision 1.14 by root, Tue Oct 29 20:59:16 2013 UTC vs. Revision 1.69 by root, Sat Nov 9 07:23:31 2019 UTC

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Comparing CBOR-XS/XS.pm (file contents):
Revision 1.14 by root, Tue Oct 29 20:59:16 2013 UTC vs.
Revision 1.69 by root, Sat Nov 9 07:23:31 2019 UTC