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Revision 1.32 by root, Sat Nov 30 18:42:27 2013 UTC vs.
Revision 1.72 by root, Sun Nov 29 21:35:06 2020 UTC

38with the added ability of supporting serialisation of Perl objects. (JSON 38with the added ability of supporting serialisation of Perl objects. (JSON
39often compresses better than CBOR though, so if you plan to compress the 39often compresses better than CBOR though, so if you plan to compress the
40data later and speed is less important you might want to compare both 40data later and speed is less important you might want to compare both
41formats first). 41formats first).
42 42
43The primary goal of this module is to be I<correct> and the secondary goal
44is to be I<fast>. To reach the latter goal it was written in C.
45
43To give you a general idea about speed, with texts in the megabyte range, 46To give you a general idea about speed, with texts in the megabyte range,
44C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or 47C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or
45L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the 48L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the
46data, the worse L<Storable> performs in comparison. 49data, the worse L<Storable> performs in comparison.
47 50
52In addition to the core CBOR data format, this module implements a 55In addition to the core CBOR data format, this module implements a
53number of extensions, to support cyclic and shared data structures 56number of extensions, to support cyclic and shared data structures
54(see C<allow_sharing> and C<allow_cycles>), string deduplication (see 57(see C<allow_sharing> and C<allow_cycles>), string deduplication (see
55C<pack_strings>) and scalar references (always enabled). 58C<pack_strings>) and scalar references (always enabled).
56 59
57The primary goal of this module is to be I<correct> and the secondary goal
58is to be I<fast>. To reach the latter goal it was written in C.
59
60See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and 60See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
61vice versa. 61vice versa.
62 62
63=cut 63=cut
64 64
65package CBOR::XS; 65package CBOR::XS;
66 66
67use common::sense; 67use common::sense;
68 68
69our $VERSION = 1.1; 69our $VERSION = 1.71;
70our @ISA = qw(Exporter); 70our @ISA = qw(Exporter);
71 71
72our @EXPORT = qw(encode_cbor decode_cbor); 72our @EXPORT = qw(encode_cbor decode_cbor);
73 73
74use Exporter; 74use Exporter;
112 112
113The mutators for flags all return the CBOR object again and thus calls can 113The mutators for flags all return the CBOR object again and thus calls can
114be chained: 114be chained:
115 115
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
120Create a new, safe/secure CBOR::XS object. This is similar to C<new>,
121but configures the coder object to be safe to use with untrusted
122data. 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
130But is more future proof (it is better to crash because of a change than
131to be exploited in other ways).
132
133=cut
134
135sub 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
138Note that nesting is implemented by recursion in C. The default value has 163Note that nesting is implemented by recursion in C. The default value has
139been chosen to be as large as typical operating systems allow without 164been chosen to be as large as typical operating systems allow without
140crashing. 165crashing.
141 166
142See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 167See 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
152effect on C<encode> (yet). 177effect on C<encode> (yet).
153 178
154If no argument is given, the limit check will be deactivated (same as when 179If no argument is given, the limit check will be deactivated (same as when
155C<0> is specified). 180C<0> is specified).
156 181
157See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 182See L<SECURITY CONSIDERATIONS>, below, for more info on why this is useful.
158 183
159=item $cbor = $cbor->allow_unknown ([$enable]) 184=item $cbor = $cbor->allow_unknown ([$enable])
160 185
161=item $enabled = $cbor->get_allow_unknown 186=item $enabled = $cbor->get_allow_unknown
162 187
180reference to the earlier value. 205reference to the earlier value.
181 206
182This means that such values will only be encoded once, and will not result 207This means that such values will only be encoded once, and will not result
183in a deep cloning of the value on decode, in decoders supporting the value 208in a deep cloning of the value on decode, in decoders supporting the value
184sharing extension. This also makes it possible to encode cyclic data 209sharing extension. This also makes it possible to encode cyclic data
185structures (which need C<allow_cycles> to ne enabled to be decoded by this 210structures (which need C<allow_cycles> to be enabled to be decoded by this
186module). 211module).
187 212
188It is recommended to leave it off unless you know your 213It is recommended to leave it off unless you know your
189communication partner supports the value sharing extensions to CBOR 214communication partner supports the value sharing extensions to CBOR
190(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
191resulting data structure might be unusable. 216resulting data structure might be unusable.
192 217
193Detecting shared values incurs a runtime overhead when values are encoded 218Detecting shared values incurs a runtime overhead when values are encoded
194that have a reference counter large than one, and might unnecessarily 219that have a reference counter large than one, and might unnecessarily
195increase the encoded size, as potentially shared values are encode as 220increase the encoded size, as potentially shared values are encoded as
196shareable whether or not they are actually shared. 221shareable whether or not they are actually shared.
197 222
198At the moment, only targets of references can be shared (e.g. scalars, 223At the moment, only targets of references can be shared (e.g. scalars,
199arrays or hashes pointed to by a reference). Weirder constructs, such as 224arrays or hashes pointed to by a reference). Weirder constructs, such as
200an array with multiple "copies" of the I<same> string, which are hard but 225an array with multiple "copies" of the I<same> string, which are hard but
218isn't prepared for this will not leak memory. 243isn't prepared for this will not leak memory.
219 244
220If C<$enable> is false (the default), then C<decode> will throw an error 245If C<$enable> is false (the default), then C<decode> will throw an error
221when it encounters a self-referential/cyclic data structure. 246when it encounters a self-referential/cyclic data structure.
222 247
248FUTURE DIRECTION: the motivation behind this option is to avoid I<real>
249cycles - future versions of this module might chose to decode cyclic data
250structures using weak references when this option is off, instead of
251throwing an error.
252
223This option does not affect C<encode> in any way - shared values and 253This option does not affect C<encode> in any way - shared values and
224references will always be decoded properly if present. 254references will always be encoded properly if present.
255
256=item $cbor = $cbor->forbid_objects ([$enable])
257
258=item $enabled = $cbor->get_forbid_objects
259
260Disables the use of the object serialiser protocol.
261
262If C<$enable> is true (or missing), then C<encode> will will throw an
263exception when it encounters perl objects that would be encoded using the
264perl-object tag (26). When C<decode> encounters such tags, it will fall
265back to the general filter/tagged logic as if this were an unknown tag (by
266default resulting in a C<CBOR::XC::Tagged> object).
267
268If C<$enable> is false (the default), then C<encode> will use the
269L<Types::Serialiser> object serialisation protocol to serialise objects
270into perl-object tags, and C<decode> will do the same to decode such tags.
271
272See L<SECURITY CONSIDERATIONS>, below, for more info on why forbidding this
273protocol can be useful.
225 274
226=item $cbor = $cbor->pack_strings ([$enable]) 275=item $cbor = $cbor->pack_strings ([$enable])
227 276
228=item $enabled = $cbor->get_pack_strings 277=item $enabled = $cbor->get_pack_strings
229 278
242the standard CBOR way. 291the standard CBOR way.
243 292
244This option does not affect C<decode> in any way - string references will 293This option does not affect C<decode> in any way - string references will
245always be decoded properly if present. 294always be decoded properly if present.
246 295
296=item $cbor = $cbor->text_keys ([$enable])
297
298=item $enabled = $cbor->get_text_keys
299
300If C<$enabled> is true (or missing), then C<encode> will encode all
301perl hash keys as CBOR text strings/UTF-8 string, upgrading them as needed.
302
303If C<$enable> is false (the default), then C<encode> will encode hash keys
304normally - upgraded perl strings (strings internally encoded as UTF-8) as
305CBOR text strings, and downgraded perl strings as CBOR byte strings.
306
307This option does not affect C<decode> in any way.
308
309This option is useful for interoperability with CBOR decoders that don't
310treat byte strings as a form of text. It is especially useful as Perl
311gives very little control over hash keys.
312
313Enabling this option can be slow, as all downgraded hash keys that are
314encoded need to be scanned and converted to UTF-8.
315
316=item $cbor = $cbor->text_strings ([$enable])
317
318=item $enabled = $cbor->get_text_strings
319
320This option works similar to C<text_keys>, above, but works on all strings
321(including hash keys), so C<text_keys> has no further effect after
322enabling C<text_strings>.
323
324If C<$enabled> is true (or missing), then C<encode> will encode all perl
325strings as CBOR text strings/UTF-8 strings, upgrading them as needed.
326
327If C<$enable> is false (the default), then C<encode> will encode strings
328normally (but see C<text_keys>) - upgraded perl strings (strings
329internally encoded as UTF-8) as CBOR text strings, and downgraded perl
330strings as CBOR byte strings.
331
332This option does not affect C<decode> in any way.
333
334This option has similar advantages and disadvantages as C<text_keys>. In
335addition, this option effectively removes the ability to automatically
336encode byte strings, which might break some C<FREEZE> and C<TO_CBOR>
337methods that rely on this.
338
339A workaround is to use explicit type casts, which are unaffected by this option.
340
341=item $cbor = $cbor->validate_utf8 ([$enable])
342
343=item $enabled = $cbor->get_validate_utf8
344
345If C<$enable> is true (or missing), then C<decode> will validate that
346elements (text strings) containing UTF-8 data in fact contain valid UTF-8
347data (instead of blindly accepting it). This validation obviously takes
348extra time during decoding.
349
350The concept of "valid UTF-8" used is perl's concept, which is a superset
351of the official UTF-8.
352
353If C<$enable> is false (the default), then C<decode> will blindly accept
354UTF-8 data, marking them as valid UTF-8 in the resulting data structure
355regardless of whether that's true or not.
356
357Perl isn't too happy about corrupted UTF-8 in strings, but should
358generally not crash or do similarly evil things. Extensions might be not
359so forgiving, so it's recommended to turn on this setting if you receive
360untrusted CBOR.
361
362This option does not affect C<encode> in any way - strings that are
363supposedly valid UTF-8 will simply be dumped into the resulting CBOR
364string without checking whether that is, in fact, true or not.
365
247=item $cbor = $cbor->filter ([$cb->($tag, $value)]) 366=item $cbor = $cbor->filter ([$cb->($tag, $value)])
248 367
249=item $cb_or_undef = $cbor->get_filter 368=item $cb_or_undef = $cbor->get_filter
250 369
251Sets or replaces the tagged value decoding filter (when C<$cb> is 370Sets or replaces the tagged value decoding filter (when C<$cb> is
263replace the tagged value in the decoded data structure, or no values, 382replace the tagged value in the decoded data structure, or no values,
264which will result in default handling, which currently means the decoder 383which will result in default handling, which currently means the decoder
265creates a C<CBOR::XS::Tagged> object to hold the tag and the value. 384creates a C<CBOR::XS::Tagged> object to hold the tag and the value.
266 385
267When the filter is cleared (the default state), the default filter 386When the filter is cleared (the default state), the default filter
268function, C<CBOR::XS::default_filter>, is used. This function simply looks 387function, C<CBOR::XS::default_filter>, is used. This function simply
269up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be 388looks up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists
270a code reference that is called with tag and value, and is responsible for 389it must be a code reference that is called with tag and value, and is
271decoding the value. If no entry exists, it returns no values. 390responsible for decoding the value. If no entry exists, it returns no
391values. C<CBOR::XS> provides a number of default filter functions already,
392the the C<%CBOR::XS::FILTER> hash can be freely extended with more.
393
394C<CBOR::XS> additionally provides an alternative filter function that is
395supposed to be safe to use with untrusted data (which the default filter
396might not), called C<CBOR::XS::safe_filter>, which works the same as
397the C<default_filter> but uses the C<%CBOR::XS::SAFE_FILTER> variable
398instead. It is prepopulated with the tag decoding functions that are
399deemed safe (basically the same as C<%CBOR::XS::FILTER> without all
400the bignum tags), and can be extended by user code as wlel, although,
401obviously, one should be very careful about adding decoding functions
402here, since the expectation is that they are safe to use on untrusted
403data, after all.
272 404
273Example: decode all tags not handled internally into C<CBOR::XS::Tagged> 405Example: decode all tags not handled internally into C<CBOR::XS::Tagged>
274objects, with no other special handling (useful when working with 406objects, with no other special handling (useful when working with
275potentially "unsafe" CBOR data). 407potentially "unsafe" CBOR data).
276 408
283 my ($tag, $value); 415 my ($tag, $value);
284 416
285 "tag 1347375694 value $value" 417 "tag 1347375694 value $value"
286 }; 418 };
287 419
420Example: provide your own filter function that looks up tags in your own
421hash:
422
423 my %my_filter = (
424 998347484 => sub {
425 my ($tag, $value);
426
427 "tag 998347484 value $value"
428 };
429 );
430
431 my $coder = CBOR::XS->new->filter (sub {
432 &{ $my_filter{$_[0]} or return }
433 });
434
435
436Example: use the safe filter function (see L<SECURITY CONSIDERATIONS> for
437more considerations on security).
438
439 CBOR::XS->new->filter (\&CBOR::XS::safe_filter)->decode ($cbor_data);
440
288=item $cbor_data = $cbor->encode ($perl_scalar) 441=item $cbor_data = $cbor->encode ($perl_scalar)
289 442
290Converts the given Perl data structure (a scalar value) to its CBOR 443Converts the given Perl data structure (a scalar value) to its CBOR
291representation. 444representation.
292 445
301when there is trailing garbage after the CBOR string, it will silently 454when there is trailing garbage after the CBOR string, it will silently
302stop parsing there and return the number of characters consumed so far. 455stop parsing there and return the number of characters consumed so far.
303 456
304This is useful if your CBOR texts are not delimited by an outer protocol 457This is useful if your CBOR texts are not delimited by an outer protocol
305and you need to know where the first CBOR string ends amd the next one 458and you need to know where the first CBOR string ends amd the next one
306starts. 459starts - CBOR strings are self-delimited, so it is possible to concatenate
460CBOR strings without any delimiters or size fields and recover their data.
307 461
308 CBOR::XS->new->decode_prefix ("......") 462 CBOR::XS->new->decode_prefix ("......")
309 => ("...", 3) 463 => ("...", 3)
464
465=back
466
467=head2 INCREMENTAL PARSING
468
469In some cases, there is the need for incremental parsing of JSON
470texts. While this module always has to keep both CBOR text and resulting
471Perl data structure in memory at one time, it does allow you to parse a
472CBOR stream incrementally, using a similar to using "decode_prefix" to see
473if a full CBOR object is available, but is much more efficient.
474
475It basically works by parsing as much of a CBOR string as possible - if
476the CBOR data is not complete yet, the pasrer will remember where it was,
477to be able to restart when more data has been accumulated. Once enough
478data is available to either decode a complete CBOR value or raise an
479error, a real decode will be attempted.
480
481A typical use case would be a network protocol that consists of sending
482and receiving CBOR-encoded messages. The solution that works with CBOR and
483about anything else is by prepending a length to every CBOR value, so the
484receiver knows how many octets to read. More compact (and slightly slower)
485would be to just send CBOR values back-to-back, as C<CBOR::XS> knows where
486a CBOR value ends, and doesn't need an explicit length.
487
488The following methods help with this:
489
490=over 4
491
492=item @decoded = $cbor->incr_parse ($buffer)
493
494This method attempts to decode exactly one CBOR value from the beginning
495of the given C<$buffer>. The value is removed from the C<$buffer> on
496success. When C<$buffer> doesn't contain a complete value yet, it returns
497nothing. Finally, when the C<$buffer> doesn't start with something
498that could ever be a valid CBOR value, it raises an exception, just as
499C<decode> would. In the latter case the decoder state is undefined and
500must be reset before being able to parse further.
501
502This method modifies the C<$buffer> in place. When no CBOR value can be
503decoded, the decoder stores the current string offset. On the next call,
504continues decoding at the place where it stopped before. For this to make
505sense, the C<$buffer> must begin with the same octets as on previous
506unsuccessful calls.
507
508You can call this method in scalar context, in which case it either
509returns a decoded value or C<undef>. This makes it impossible to
510distinguish between CBOR null values (which decode to C<undef>) and an
511unsuccessful decode, which is often acceptable.
512
513=item @decoded = $cbor->incr_parse_multiple ($buffer)
514
515Same as C<incr_parse>, but attempts to decode as many CBOR values as
516possible in one go, instead of at most one. Calls to C<incr_parse> and
517C<incr_parse_multiple> can be interleaved.
518
519=item $cbor->incr_reset
520
521Resets the incremental decoder. This throws away any saved state, so that
522subsequent calls to C<incr_parse> or C<incr_parse_multiple> start to parse
523a new CBOR value from the beginning of the C<$buffer> again.
524
525This method can be called at any time, but it I<must> be called if you want
526to change your C<$buffer> or there was a decoding error and you want to
527reuse the C<$cbor> object for future incremental parsings.
310 528
311=back 529=back
312 530
313 531
314=head1 MAPPING 532=head1 MAPPING
387 605
388=item hash references 606=item hash references
389 607
390Perl hash references become CBOR maps. As there is no inherent ordering in 608Perl hash references become CBOR maps. As there is no inherent ordering in
391hash keys (or CBOR maps), they will usually be encoded in a pseudo-random 609hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
392order. This order can be different each time a hahs is encoded. 610order. This order can be different each time a hash is encoded.
393 611
394Currently, tied hashes will use the indefinite-length format, while normal 612Currently, tied hashes will use the indefinite-length format, while normal
395hashes will use the fixed-length format. 613hashes will use the fixed-length format.
396 614
397=item array references 615=item array references
450 my $x = 3.1; # some variable containing a number 668 my $x = 3.1; # some variable containing a number
451 "$x"; # stringified 669 "$x"; # stringified
452 $x .= ""; # another, more awkward way to stringify 670 $x .= ""; # another, more awkward way to stringify
453 print $x; # perl does it for you, too, quite often 671 print $x; # perl does it for you, too, quite often
454 672
455You can force whether a string ie encoded as byte or text string by using 673You can force whether a string is encoded as byte or text string by using
456C<utf8::upgrade> and C<utf8::downgrade>): 674C<utf8::upgrade> and C<utf8::downgrade> (if C<text_strings> is disabled).
457 675
458 utf8::upgrade $x; # encode $x as text string 676 utf8::upgrade $x; # encode $x as text string
459 utf8::downgrade $x; # encode $x as byte string 677 utf8::downgrade $x; # encode $x as byte string
460 678
679More options are available, see L<TYPE CASTS>, below, and the C<text_keys>
680and C<text_strings> options.
681
461Perl doesn't define what operations up- and downgrade strings, so if the 682Perl doesn't define what operations up- and downgrade strings, so if the
462difference between byte and text is important, you should up- or downgrade 683difference between byte and text is important, you should up- or downgrade
463your string as late as possible before encoding. 684your string as late as possible before encoding. You can also force the
685use of CBOR text strings by using C<text_keys> or C<text_strings>.
464 686
465You can force the type to be a CBOR number by numifying it: 687You can force the type to be a CBOR number by numifying it:
466 688
467 my $x = "3"; # some variable containing a string 689 my $x = "3"; # some variable containing a string
468 $x += 0; # numify it, ensuring it will be dumped as a number 690 $x += 0; # numify it, ensuring it will be dumped as a number
479represent numerical values are supported, but might suffer loss of 701represent numerical values are supported, but might suffer loss of
480precision. 702precision.
481 703
482=back 704=back
483 705
706=head2 TYPE CASTS
707
708B<EXPERIMENTAL>: As an experimental extension, C<CBOR::XS> allows you to
709force specific cbor types to be used when encoding. That allows you to
710encode types not normally accessible (e.g. half floats) as well as force
711string types even when C<text_strings> is in effect.
712
713Type forcing is done by calling a special "cast" function which keeps a
714copy of the value and returns a new value that can be handed over to any
715CBOR encoder function.
716
717The following casts are currently available (all of which are unary operators):
718
719=over
720
721=item CBOR::XS::as_int $value
722
723Forces the value to be encoded as some form of (basic, not bignum) integer
724type.
725
726=item CBOR::XS::as_text $value
727
728Forces the value to be encoded as (UTF-8) text values.
729
730=item CBOR::XS::as_bytes $value
731
732Forces the value to be encoded as a (binary) string value.
733
734=item CBOR::XS::as_float16 $value
735
736Forces half-float (IEEE 754 binary16) encoding of the given value.
737
738=item CBOR::XS::as_float32 $value
739
740Forces single-float (IEEE 754 binary32) encoding of the given value.
741
742=item CBOR::XS::as_float64 $value
743
744Forces double-float (IEEE 754 binary64) encoding of the given value.
745
746=item, CBOR::XS::as_cbor $cbor_text
747
748Bot a type cast per-se, this type cast forces the argument to eb encoded
749as-is. This can be used to embed pre-encoded CBOR data.
750
751Note that no checking on the validity of the C<$cbor_text> is done - it's
752the callers responsibility to correctly encode values.
753
754=back
755
756Example: encode a perl string as binary even though C<text_strings> is in
757effect.
758
759 CBOR::XS->new->text_strings->encode ([4, "text", CBOR::XS::bytes "bytevalue"]);
760
761=cut
762
763sub CBOR::XS::as_int ($) { bless [$_[0], 0, undef], CBOR::XS::Tagged:: }
764sub CBOR::XS::as_cbor ($) { bless [$_[0], 1, undef], CBOR::XS::Tagged:: }
765sub CBOR::XS::as_bytes ($) { bless [$_[0], 2, undef], CBOR::XS::Tagged:: }
766sub CBOR::XS::as_text ($) { bless [$_[0], 3, undef], CBOR::XS::Tagged:: }
767sub CBOR::XS::as_float16 ($) { bless [$_[0], 4, undef], CBOR::XS::Tagged:: }
768sub CBOR::XS::as_float32 ($) { bless [$_[0], 5, undef], CBOR::XS::Tagged:: }
769sub CBOR::XS::as_float64 ($) { bless [$_[0], 6, undef], CBOR::XS::Tagged:: }
770
484=head2 OBJECT SERIALISATION 771=head2 OBJECT SERIALISATION
485 772
486This module implements both a CBOR-specific and the generic 773This module implements both a CBOR-specific and the generic
487L<Types::Serialier> object serialisation protocol. The following 774L<Types::Serialier> object serialisation protocol. The following
488subsections explain both methods. 775subsections explain both methods.
569 "$self" # encode url string 856 "$self" # encode url string
570 } 857 }
571 858
572 sub URI::THAW { 859 sub URI::THAW {
573 my ($class, $serialiser, $uri) = @_; 860 my ($class, $serialiser, $uri) = @_;
574
575 $class->new ($uri) 861 $class->new ($uri)
576 } 862 }
577 863
578Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For 864Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For
579example, a C<FREEZE> method that returns "type", "id" and "variant" values 865example, a C<FREEZE> method that returns "type", "id" and "variant" values
710additional tags (such as base64url). 996additional tags (such as base64url).
711 997
712=head2 ENFORCED TAGS 998=head2 ENFORCED TAGS
713 999
714These tags are always handled when decoding, and their handling cannot be 1000These tags are always handled when decoding, and their handling cannot be
715overriden by the user. 1001overridden by the user.
716 1002
717=over 4 1003=over 4
718 1004
719=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>) 1005=item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>)
720 1006
721These tags are automatically created (and decoded) for serialisable 1007These tags are automatically created (and decoded) for serialisable
722objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object 1008objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
723serialisation protocol). See L<OBJECT SERIALISATION> for details. 1009serialisation protocol). See L<OBJECT SERIALISATION> for details.
724 1010
725=item 28, 29 (shareable, sharedref, L <http://cbor.schmorp.de/value-sharing>) 1011=item 28, 29 (shareable, sharedref, L<http://cbor.schmorp.de/value-sharing>)
726 1012
727These tags are automatically decoded when encountered (and they do not 1013These tags are automatically decoded when encountered (and they do not
728result in a cyclic data structure, see C<allow_cycles>), resulting in 1014result in a cyclic data structure, see C<allow_cycles>), resulting in
729shared values in the decoded object. They are only encoded, however, when 1015shared values in the decoded object. They are only encoded, however, when
730C<allow_sharing> is enabled. 1016C<allow_sharing> is enabled.
740will be shared, others will not. While non-reference shared values can be 1026will be shared, others will not. While non-reference shared values can be
741generated in Perl with some effort, they were considered too unimportant 1027generated in Perl with some effort, they were considered too unimportant
742to be supported in the encoder. The decoder, however, will decode these 1028to be supported in the encoder. The decoder, however, will decode these
743values as shared values. 1029values as shared values.
744 1030
745=item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>) 1031=item 256, 25 (stringref-namespace, stringref, L<http://cbor.schmorp.de/stringref>)
746 1032
747These tags are automatically decoded when encountered. They are only 1033These tags are automatically decoded when encountered. They are only
748encoded, however, when C<pack_strings> is enabled. 1034encoded, however, when C<pack_strings> is enabled.
749 1035
750=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>) 1036=item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
751 1037
752This tag is automatically generated when a reference are encountered (with 1038This tag is automatically generated when a reference are encountered (with
753the exception of hash and array refernces). It is converted to a reference 1039the exception of hash and array references). It is converted to a reference
754when decoding. 1040when decoding.
755 1041
756=item 55799 (self-describe CBOR, RFC 7049) 1042=item 55799 (self-describe CBOR, RFC 7049)
757 1043
758This value is not generated on encoding (unless explicitly requested by 1044This value is not generated on encoding (unless explicitly requested by
761=back 1047=back
762 1048
763=head2 NON-ENFORCED TAGS 1049=head2 NON-ENFORCED TAGS
764 1050
765These tags have default filters provided when decoding. Their handling can 1051These tags have default filters provided when decoding. Their handling can
766be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by 1052be overridden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by
767providing a custom C<filter> callback when decoding. 1053providing a custom C<filter> callback when decoding.
768 1054
769When they result in decoding into a specific Perl class, the module 1055When they result in decoding into a specific Perl class, the module
770usually provides a corresponding C<TO_CBOR> method as well. 1056usually provides a corresponding C<TO_CBOR> method as well.
771 1057
774provide these modules. The decoding usually fails with an exception if the 1060provide these modules. The decoding usually fails with an exception if the
775required module cannot be loaded. 1061required module cannot be loaded.
776 1062
777=over 4 1063=over 4
778 1064
1065=item 0, 1 (date/time string, seconds since the epoch)
1066
1067These tags are decoded into L<Time::Piece> objects. The corresponding
1068C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently.
1069
1070The L<Time::Piece> API is generally surprisingly bad, and fractional
1071seconds are only accidentally kept intact, so watch out. On the plus side,
1072the module comes with perl since 5.10, which has to count for something.
1073
779=item 2, 3 (positive/negative bignum) 1074=item 2, 3 (positive/negative bignum)
780 1075
781These tags are decoded into L<Math::BigInt> objects. The corresponding 1076These tags are decoded into L<Math::BigInt> objects. The corresponding
782C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR 1077C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
783integers, and others into positive/negative CBOR bignums. 1078integers, and others into positive/negative CBOR bignums.
784 1079
785=item 4, 5 (decimal fraction/bigfloat) 1080=item 4, 5, 264, 265 (decimal fraction/bigfloat)
786 1081
787Both decimal fractions and bigfloats are decoded into L<Math::BigFloat> 1082Both decimal fractions and bigfloats are decoded into L<Math::BigFloat>
788objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always> 1083objects. The corresponding C<Math::BigFloat::TO_CBOR> method I<always>
789encodes into a decimal fraction. 1084encodes into a decimal fraction (either tag 4 or 264).
790 1085
791CBOR cannot represent bigfloats with I<very> large exponents - conversion 1086NaN and infinities are not encoded properly, as they cannot be represented
792of such big float objects is undefined. 1087in CBOR.
793 1088
794Also, NaN and infinities are not encoded properly. 1089See L<BIGNUM SECURITY CONSIDERATIONS> for more info.
1090
1091=item 30 (rational numbers)
1092
1093These tags are decoded into L<Math::BigRat> objects. The corresponding
1094C<Math::BigRat::TO_CBOR> method encodes rational numbers with denominator
1095C<1> via their numerator only, i.e., they become normal integers or
1096C<bignums>.
1097
1098See L<BIGNUM SECURITY CONSIDERATIONS> for more info.
795 1099
796=item 21, 22, 23 (expected later JSON conversion) 1100=item 21, 22, 23 (expected later JSON conversion)
797 1101
798CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these 1102CBOR::XS is not a CBOR-to-JSON converter, and will simply ignore these
799tags. 1103tags.
804C<URI::TO_CBOR> method again results in a CBOR URI value. 1108C<URI::TO_CBOR> method again results in a CBOR URI value.
805 1109
806=back 1110=back
807 1111
808=cut 1112=cut
809
810our %FILTER = (
811 # 0 # rfc4287 datetime, utf-8
812 # 1 # unix timestamp, any
813
814 2 => sub { # pos bigint
815 require Math::BigInt;
816 Math::BigInt->new ("0x" . unpack "H*", pop)
817 },
818
819 3 => sub { # neg bigint
820 require Math::BigInt;
821 -Math::BigInt->new ("0x" . unpack "H*", pop)
822 },
823
824 4 => sub { # decimal fraction, array
825 require Math::BigFloat;
826 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
827 },
828
829 5 => sub { # bigfloat, array
830 require Math::BigFloat;
831 scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
832 },
833
834 21 => sub { pop }, # expected conversion to base64url encoding
835 22 => sub { pop }, # expected conversion to base64 encoding
836 23 => sub { pop }, # expected conversion to base16 encoding
837
838 # 24 # embedded cbor, byte string
839
840 32 => sub {
841 require URI;
842 URI->new (pop)
843 },
844
845 # 33 # base64url rfc4648, utf-8
846 # 34 # base64 rfc46484, utf-8
847 # 35 # regex pcre/ecma262, utf-8
848 # 36 # mime message rfc2045, utf-8
849);
850
851 1113
852=head1 CBOR and JSON 1114=head1 CBOR and JSON
853 1115
854CBOR is supposed to implement a superset of the JSON data model, and is, 1116CBOR is supposed to implement a superset of the JSON data model, and is,
855with some coercion, able to represent all JSON texts (something that other 1117with some coercion, able to represent all JSON texts (something that other
864CBOR intact. 1126CBOR intact.
865 1127
866 1128
867=head1 SECURITY CONSIDERATIONS 1129=head1 SECURITY CONSIDERATIONS
868 1130
869When you are using CBOR in a protocol, talking to untrusted potentially 1131Tl;dr... if you want to decode or encode CBOR from untrusted sources, you
870hostile creatures requires relatively few measures. 1132should start with a coder object created via C<new_safe> (which implements
1133the mitigations explained below):
871 1134
1135 my $coder = CBOR::XS->new_safe;
1136
1137 my $data = $coder->decode ($cbor_text);
1138 my $cbor = $coder->encode ($data);
1139
1140Longer version: When you are using CBOR in a protocol, talking to
1141untrusted potentially hostile creatures requires some thought:
1142
1143=over 4
1144
1145=item Security of the CBOR decoder itself
1146
872First of all, your CBOR decoder should be secure, that is, should not have 1147First and foremost, your CBOR decoder should be secure, that is, should
1148not have any buffer overflows or similar bugs that could potentially be
873any buffer overflows. Obviously, this module should ensure that and I am 1149exploited. Obviously, this module should ensure that and I am trying hard
874trying hard on making that true, but you never know. 1150on making that true, but you never know.
875 1151
1152=item CBOR::XS can invoke almost arbitrary callbacks during decoding
1153
1154CBOR::XS supports object serialisation - decoding CBOR can cause calls
1155to I<any> C<THAW> method in I<any> package that exists in your process
1156(that is, CBOR::XS will not try to load modules, but any existing C<THAW>
1157method or function can be called, so they all have to be secure).
1158
1159Less obviously, it will also invoke C<TO_CBOR> and C<FREEZE> methods -
1160even if all your C<THAW> methods are secure, encoding data structures from
1161untrusted sources can invoke those and trigger bugs in those.
1162
1163So, if you are not sure about the security of all the modules you
1164have loaded (you shouldn't), you should disable this part using
1165C<forbid_objects> or using C<new_safe>.
1166
1167=item CBOR can be extended with tags that call library code
1168
1169CBOR can be extended with tags, and C<CBOR::XS> has a registry of
1170conversion functions for many existing tags that can be extended via
1171third-party modules (see the C<filter> method).
1172
1173If you don't trust these, you should configure the "safe" filter function,
1174C<CBOR::XS::safe_filter> (C<new_safe> does this), which by default only
1175includes conversion functions that are considered "safe" by the author
1176(but again, they can be extended by third party modules).
1177
1178Depending on your level of paranoia, you can use the "safe" filter:
1179
1180 $cbor->filter (\&CBOR::XS::safe_filter);
1181
1182... your own filter...
1183
1184 $cbor->filter (sub { ... do your stuffs here ... });
1185
1186... or even no filter at all, disabling all tag decoding:
1187
1188 $cbor->filter (sub { });
1189
1190This is never a problem for encoding, as the tag mechanism only exists in
1191CBOR texts.
1192
1193=item Resource-starving attacks: object memory usage
1194
876Second, you need to avoid resource-starving attacks. That means you should 1195You need to avoid resource-starving attacks. That means you should limit
877limit the size of CBOR data you accept, or make sure then when your 1196the size of CBOR data you accept, or make sure then when your resources
878resources run out, that's just fine (e.g. by using a separate process that 1197run out, that's just fine (e.g. by using a separate process that can
879can crash safely). The size of a CBOR string in octets is usually a good 1198crash safely). The size of a CBOR string in octets is usually a good
880indication of the size of the resources required to decode it into a Perl 1199indication of the size of the resources required to decode it into a Perl
881structure. While CBOR::XS can check the size of the CBOR text, it might be 1200structure. While CBOR::XS can check the size of the CBOR text (using
882too late when you already have it in memory, so you might want to check 1201C<max_size> - done by C<new_safe>), it might be too late when you already
883the size before you accept the string. 1202have it in memory, so you might want to check the size before you accept
1203the string.
884 1204
1205As for encoding, it is possible to construct data structures that are
1206relatively small but result in large CBOR texts (for example by having an
1207array full of references to the same big data structure, which will all be
1208deep-cloned during encoding by default). This is rarely an actual issue
1209(and the worst case is still just running out of memory), but you can
1210reduce this risk by using C<allow_sharing>.
1211
1212=item Resource-starving attacks: stack overflows
1213
885Third, CBOR::XS recurses using the C stack when decoding objects and 1214CBOR::XS recurses using the C stack when decoding objects and arrays. The
886arrays. The C stack is a limited resource: for instance, on my amd64 1215C stack is a limited resource: for instance, on my amd64 machine with 8MB
887machine with 8MB of stack size I can decode around 180k nested arrays but 1216of stack size I can decode around 180k nested arrays but only 14k nested
888only 14k nested CBOR objects (due to perl itself recursing deeply on croak 1217CBOR objects (due to perl itself recursing deeply on croak to free the
889to free the temporary). If that is exceeded, the program crashes. To be 1218temporary). If that is exceeded, the program crashes. To be conservative,
890conservative, the default nesting limit is set to 512. If your process 1219the default nesting limit is set to 512. If your process has a smaller
891has a smaller stack, you should adjust this setting accordingly with the 1220stack, you should adjust this setting accordingly with the C<max_depth>
892C<max_depth> method. 1221method.
1222
1223=item Resource-starving attacks: CPU en-/decoding complexity
1224
1225CBOR::XS will use the L<Math::BigInt>, L<Math::BigFloat> and
1226L<Math::BigRat> libraries to represent encode/decode bignums. These can be
1227very slow (as in, centuries of CPU time) and can even crash your program
1228(and are generally not very trustworthy). See the next section on bignum
1229security for details.
1230
1231=item Data breaches: leaking information in error messages
1232
1233CBOR::XS might leak contents of your Perl data structures in its error
1234messages, so when you serialise sensitive information you might want to
1235make sure that exceptions thrown by CBOR::XS will not end up in front of
1236untrusted eyes.
1237
1238=item Something else...
893 1239
894Something else could bomb you, too, that I forgot to think of. In that 1240Something else could bomb you, too, that I forgot to think of. In that
895case, you get to keep the pieces. I am always open for hints, though... 1241case, you get to keep the pieces. I am always open for hints, though...
896 1242
897Also keep in mind that CBOR::XS might leak contents of your Perl data 1243=back
898structures in its error messages, so when you serialise sensitive 1244
899information you might want to make sure that exceptions thrown by CBOR::XS 1245
900will not end up in front of untrusted eyes. 1246=head1 BIGNUM SECURITY CONSIDERATIONS
1247
1248CBOR::XS provides a C<TO_CBOR> method for both L<Math::BigInt> and
1249L<Math::BigFloat> that tries to encode the number in the simplest possible
1250way, that is, either a CBOR integer, a CBOR bigint/decimal fraction (tag
12514) or an arbitrary-exponent decimal fraction (tag 264). Rational numbers
1252(L<Math::BigRat>, tag 30) can also contain bignums as members.
1253
1254CBOR::XS will also understand base-2 bigfloat or arbitrary-exponent
1255bigfloats (tags 5 and 265), but it will never generate these on its own.
1256
1257Using the built-in L<Math::BigInt::Calc> support, encoding and decoding
1258decimal fractions is generally fast. Decoding bigints can be slow for very
1259big numbers (tens of thousands of digits, something that could potentially
1260be caught by limiting the size of CBOR texts), and decoding bigfloats or
1261arbitrary-exponent bigfloats can be I<extremely> slow (minutes, decades)
1262for large exponents (roughly 40 bit and longer).
1263
1264Additionally, L<Math::BigInt> can take advantage of other bignum
1265libraries, such as L<Math::GMP>, which cannot handle big floats with large
1266exponents, and might simply abort or crash your program, due to their code
1267quality.
1268
1269This can be a concern if you want to parse untrusted CBOR. If it is, you
1270might want to disable decoding of tag 2 (bigint) and 3 (negative bigint)
1271types. You should also disable types 5 and 265, as these can be slow even
1272without bigints.
1273
1274Disabling bigints will also partially or fully disable types that rely on
1275them, e.g. rational numbers that use bignums.
1276
901 1277
902=head1 CBOR IMPLEMENTATION NOTES 1278=head1 CBOR IMPLEMENTATION NOTES
903 1279
904This section contains some random implementation notes. They do not 1280This section contains some random implementation notes. They do not
905describe guaranteed behaviour, but merely behaviour as-is implemented 1281describe guaranteed behaviour, but merely behaviour as-is implemented
919 1295
920 1296
921=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT 1297=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
922 1298
923On perls that were built without 64 bit integer support (these are rare 1299On perls that were built without 64 bit integer support (these are rare
924nowadays, even on 32 bit architectures), support for any kind of 64 bit 1300nowadays, even on 32 bit architectures, as all major Perl distributions
1301are built with 64 bit integer support), support for any kind of 64 bit
925integer in CBOR is very limited - most likely, these 64 bit values will 1302value in CBOR is very limited - most likely, these 64 bit values will
926be truncated, corrupted, or otherwise not decoded correctly. This also 1303be truncated, corrupted, or otherwise not decoded correctly. This also
927includes string, array and map sizes that are stored as 64 bit integers. 1304includes string, float, array and map sizes that are stored as 64 bit
1305integers.
928 1306
929 1307
930=head1 THREADS 1308=head1 THREADS
931 1309
932This module is I<not> guaranteed to be thread safe and there are no 1310This module is I<not> guaranteed to be thread safe and there are no
946Please refrain from using rt.cpan.org or any other bug reporting 1324Please refrain from using rt.cpan.org or any other bug reporting
947service. I put the contact address into my modules for a reason. 1325service. I put the contact address into my modules for a reason.
948 1326
949=cut 1327=cut
950 1328
1329# clumsy and slow hv_store-in-hash helper function
1330sub _hv_store {
1331 $_[0]{$_[1]} = $_[2];
1332}
1333
951our %FILTER = ( 1334our %FILTER = (
952 # 0 # rfc4287 datetime, utf-8 1335 0 => sub { # rfc4287 datetime, utf-8
953 # 1 # unix timestamp, any 1336 require Time::Piece;
1337 # Time::Piece::Strptime uses the "incredibly flexible date parsing routine"
1338 # from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything
1339 # else either. Whats incredibe over standard strptime totally escapes me.
1340 # doesn't do fractional times, either. sigh.
1341 # In fact, it's all a lie, it uses whatever strptime it wants, and of course,
1342 # they are all incompatible. The openbsd one simply ignores %z (but according to the
1343 # docs, it would be much more incredibly flexible indeed. If it worked, that is.).
1344 scalar eval {
1345 my $s = $_[1];
1346
1347 $s =~ s/Z$/+00:00/;
1348 $s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$//
1349 or die;
1350
1351 my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully
1352 my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S");
1353
1354 Time::Piece::gmtime ($d->epoch + $b)
1355 } || die "corrupted CBOR date/time string ($_[0])";
1356 },
1357
1358 1 => sub { # seconds since the epoch, possibly fractional
1359 require Time::Piece;
1360 scalar Time::Piece::gmtime (pop)
1361 },
954 1362
955 2 => sub { # pos bigint 1363 2 => sub { # pos bigint
956 require Math::BigInt; 1364 require Math::BigInt;
957 Math::BigInt->new ("0x" . unpack "H*", pop) 1365 Math::BigInt->new ("0x" . unpack "H*", pop)
958 }, 1366 },
965 4 => sub { # decimal fraction, array 1373 4 => sub { # decimal fraction, array
966 require Math::BigFloat; 1374 require Math::BigFloat;
967 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0]) 1375 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
968 }, 1376 },
969 1377
1378 264 => sub { # decimal fraction with arbitrary exponent
1379 require Math::BigFloat;
1380 Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
1381 },
1382
970 5 => sub { # bigfloat, array 1383 5 => sub { # bigfloat, array
971 require Math::BigFloat; 1384 require Math::BigFloat;
972 scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2) 1385 scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
1386 },
1387
1388 265 => sub { # bigfloat with arbitrary exponent
1389 require Math::BigFloat;
1390 scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
1391 },
1392
1393 30 => sub { # rational number
1394 require Math::BigRat;
1395 Math::BigRat->new ("$_[1][0]/$_[1][1]") # separate parameters only work in recent versons
973 }, 1396 },
974 1397
975 21 => sub { pop }, # expected conversion to base64url encoding 1398 21 => sub { pop }, # expected conversion to base64url encoding
976 22 => sub { pop }, # expected conversion to base64 encoding 1399 22 => sub { pop }, # expected conversion to base64 encoding
977 23 => sub { pop }, # expected conversion to base16 encoding 1400 23 => sub { pop }, # expected conversion to base16 encoding
987 # 34 # base64 rfc46484, utf-8 1410 # 34 # base64 rfc46484, utf-8
988 # 35 # regex pcre/ecma262, utf-8 1411 # 35 # regex pcre/ecma262, utf-8
989 # 36 # mime message rfc2045, utf-8 1412 # 36 # mime message rfc2045, utf-8
990); 1413);
991 1414
992sub CBOR::XS::default_filter { 1415sub default_filter {
993 &{ $FILTER{$_[0]} or return } 1416 &{ $FILTER{$_[0]} or return }
1417}
1418
1419our %SAFE_FILTER = map { $_ => $FILTER{$_} } 0, 1, 21, 22, 23, 32;
1420
1421sub safe_filter {
1422 &{ $SAFE_FILTER{$_[0]} or return }
994} 1423}
995 1424
996sub URI::TO_CBOR { 1425sub URI::TO_CBOR {
997 my $uri = $_[0]->as_string; 1426 my $uri = $_[0]->as_string;
998 utf8::upgrade $uri; 1427 utf8::upgrade $uri;
999 CBOR::XS::tag 32, $uri 1428 tag 32, $uri
1000} 1429}
1001 1430
1002sub Math::BigInt::TO_CBOR { 1431sub Math::BigInt::TO_CBOR {
1003 if ($_[0] >= -2147483648 && $_[0] <= 2147483647) { 1432 if (-2147483648 <= $_[0] && $_[0] <= 2147483647) {
1004 $_[0]->numify 1433 $_[0]->numify
1005 } else { 1434 } else {
1006 my $hex = substr $_[0]->as_hex, 2; 1435 my $hex = substr $_[0]->as_hex, 2;
1007 $hex = "0$hex" if 1 & length $hex; # sigh 1436 $hex = "0$hex" if 1 & length $hex; # sigh
1008 CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex 1437 tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
1009 } 1438 }
1010} 1439}
1011 1440
1012sub Math::BigFloat::TO_CBOR { 1441sub Math::BigFloat::TO_CBOR {
1013 my ($m, $e) = $_[0]->parts; 1442 my ($m, $e) = $_[0]->parts;
1443
1444 -9223372036854775808 <= $e && $e <= 18446744073709551615
1014 CBOR::XS::tag 4, [$e->numify, $m] 1445 ? tag 4, [$e->numify, $m]
1446 : tag 264, [$e, $m]
1447}
1448
1449sub Math::BigRat::TO_CBOR {
1450 my ($n, $d) = $_[0]->parts;
1451
1452 # older versions of BigRat need *1, as they not always return numbers
1453
1454 $d*1 == 1
1455 ? $n*1
1456 : tag 30, [$n*1, $d*1]
1457}
1458
1459sub Time::Piece::TO_CBOR {
1460 tag 1, 0 + $_[0]->epoch
1015} 1461}
1016 1462
1017XSLoader::load "CBOR::XS", $VERSION; 1463XSLoader::load "CBOR::XS", $VERSION;
1018 1464
1019=head1 SEE ALSO 1465=head1 SEE ALSO

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