1/* Copyright (c) 2014, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15#ifndef OPENSSL_HEADER_BYTESTRING_H
16#define OPENSSL_HEADER_BYTESTRING_H
17
18#include <openssl/base.h>
19
20#if defined(__cplusplus)
21extern "C" {
22#endif
23
24
25/* Bytestrings are used for parsing and building TLS and ASN.1 messages.
26 *
27 * A "CBS" (CRYPTO ByteString) represents a string of bytes in memory and
28 * provides utility functions for safely parsing length-prefixed structures
29 * like TLS and ASN.1 from it.
30 *
31 * A "CBB" (CRYPTO ByteBuilder) is a memory buffer that grows as needed and
32 * provides utility functions for building length-prefixed messages. */
33
34
35/* CRYPTO ByteString */
36
37struct cbs_st {
38  const uint8_t *data;
39  size_t len;
40};
41
42/* CBS_init sets |cbs| to point to |data|. It does not take ownership of
43 * |data|. */
44OPENSSL_EXPORT void CBS_init(CBS *cbs, const uint8_t *data, size_t len);
45
46/* CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero
47 * otherwise. */
48OPENSSL_EXPORT int CBS_skip(CBS *cbs, size_t len);
49
50/* CBS_data returns a pointer to the contents of |cbs|. */
51OPENSSL_EXPORT const uint8_t *CBS_data(const CBS *cbs);
52
53/* CBS_len returns the number of bytes remaining in |cbs|. */
54OPENSSL_EXPORT size_t CBS_len(const CBS *cbs);
55
56/* CBS_stow copies the current contents of |cbs| into |*out_ptr| and
57 * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with
58 * OPENSSL_free. It returns one on success and zero on allocation failure. On
59 * success, |*out_ptr| should be freed with OPENSSL_free. If |cbs| is empty,
60 * |*out_ptr| will be NULL. */
61OPENSSL_EXPORT int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len);
62
63/* CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a
64 * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed
65 * with OPENSSL_free. It returns one on success and zero on allocation
66 * failure. On success, |*out_ptr| should be freed with OPENSSL_free.
67 *
68 * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call
69 * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. */
70OPENSSL_EXPORT int CBS_strdup(const CBS *cbs, char **out_ptr);
71
72/* CBS_contains_zero_byte returns one if the current contents of |cbs| contains
73 * a NUL byte and zero otherwise. */
74OPENSSL_EXPORT int CBS_contains_zero_byte(const CBS *cbs);
75
76/* CBS_mem_equal compares the current contents of |cbs| with the |len| bytes
77 * starting at |data|. If they're equal, it returns one, otherwise zero. If the
78 * lengths match, it uses a constant-time comparison. */
79OPENSSL_EXPORT int CBS_mem_equal(const CBS *cbs, const uint8_t *data,
80                                 size_t len);
81
82/* CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It
83 * returns one on success and zero on error. */
84OPENSSL_EXPORT int CBS_get_u8(CBS *cbs, uint8_t *out);
85
86/* CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and
87 * advances |cbs|. It returns one on success and zero on error. */
88OPENSSL_EXPORT int CBS_get_u16(CBS *cbs, uint16_t *out);
89
90/* CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and
91 * advances |cbs|. It returns one on success and zero on error. */
92OPENSSL_EXPORT int CBS_get_u24(CBS *cbs, uint32_t *out);
93
94/* CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs|
95 * and advances |cbs|. It returns one on success and zero on error. */
96OPENSSL_EXPORT int CBS_get_u32(CBS *cbs, uint32_t *out);
97
98/* CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances
99 * |cbs|. It returns one on success and zero on error. */
100OPENSSL_EXPORT int CBS_get_bytes(CBS *cbs, CBS *out, size_t len);
101
102/* CBS_copy_bytes copies the next |len| bytes from |cbs| to |out| and advances
103 * |cbs|. It returns one on success and zero on error. */
104OPENSSL_EXPORT int CBS_copy_bytes(CBS *cbs, uint8_t *out, size_t len);
105
106/* CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit,
107 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one
108 * on success and zero on error. */
109OPENSSL_EXPORT int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out);
110
111/* CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit,
112 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It
113 * returns one on success and zero on error. */
114OPENSSL_EXPORT int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out);
115
116/* CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit,
117 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It
118 * returns one on success and zero on error. */
119OPENSSL_EXPORT int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out);
120
121
122/* Parsing ASN.1 */
123
124#define CBS_ASN1_BOOLEAN 0x1
125#define CBS_ASN1_INTEGER 0x2
126#define CBS_ASN1_BITSTRING 0x3
127#define CBS_ASN1_OCTETSTRING 0x4
128#define CBS_ASN1_NULL 0x5
129#define CBS_ASN1_OBJECT 0x6
130#define CBS_ASN1_ENUMERATED 0xa
131#define CBS_ASN1_SEQUENCE (0x10 | CBS_ASN1_CONSTRUCTED)
132#define CBS_ASN1_SET (0x11 | CBS_ASN1_CONSTRUCTED)
133#define CBS_ASN1_GENERALIZEDTIME 0x18
134
135#define CBS_ASN1_CONSTRUCTED 0x20
136#define CBS_ASN1_CONTEXT_SPECIFIC 0x80
137
138/* CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not
139 * including tag and length bytes) and advances |cbs| over it. The ASN.1
140 * element must match |tag_value|. It returns one on success and zero
141 * on error.
142 *
143 * Tag numbers greater than 30 are not supported (i.e. short form only). */
144OPENSSL_EXPORT int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value);
145
146/* CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the
147 * ASN.1 header bytes too. */
148OPENSSL_EXPORT int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value);
149
150/* CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one
151 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If
152 * |cbs| is empty or the tag does not match, it returns zero. Note: if
153 * it returns one, CBS_get_asn1 may still fail if the rest of the
154 * element is malformed. */
155OPENSSL_EXPORT int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value);
156
157/* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from
158 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to
159 * the tag number and |*out_header_len| to the length of the ASN.1 header. Each
160 * of |out|, |out_tag|, and |out_header_len| may be NULL to ignore the value.
161 *
162 * Tag numbers greater than 30 are not supported (i.e. short form only). */
163OPENSSL_EXPORT int CBS_get_any_asn1_element(CBS *cbs, CBS *out,
164                                            unsigned *out_tag,
165                                            size_t *out_header_len);
166
167/* CBS_get_any_ber_asn1_element acts the same as |CBS_get_any_asn1_element| but
168 * also allows indefinite-length elements to be returned. In that case,
169 * |*out_header_len| and |CBS_len(out)| will both be two as only the header is
170 * returned, otherwise it behaves the same as the previous function. */
171OPENSSL_EXPORT int CBS_get_any_ber_asn1_element(CBS *cbs, CBS *out,
172                                                unsigned *out_tag,
173                                                size_t *out_header_len);
174
175/* CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1|
176 * and sets |*out| to its value. It returns one on success and zero on error,
177 * where error includes the integer being negative, or too large to represent
178 * in 64 bits. */
179OPENSSL_EXPORT int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out);
180
181/* CBS_get_optional_asn1 gets an optional explicitly-tagged element from |cbs|
182 * tagged with |tag| and sets |*out| to its contents. If present and if
183 * |out_present| is not NULL, it sets |*out_present| to one, otherwise zero. It
184 * returns one on success, whether or not the element was present, and zero on
185 * decode failure. */
186OPENSSL_EXPORT int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present,
187                                         unsigned tag);
188
189/* CBS_get_optional_asn1_octet_string gets an optional
190 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets
191 * |*out| to the string and |*out_present| to one. Otherwise, it sets
192 * |*out| to empty and |*out_present| to zero. |out_present| may be
193 * NULL. It returns one on success, whether or not the element was
194 * present, and zero on decode failure. */
195OPENSSL_EXPORT int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out,
196                                                      int *out_present,
197                                                      unsigned tag);
198
199/* CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged
200 * INTEGER from |cbs|. If present, it sets |*out| to the
201 * value. Otherwise, it sets |*out| to |default_value|. It returns one
202 * on success, whether or not the element was present, and zero on
203 * decode failure. */
204OPENSSL_EXPORT int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out,
205                                                unsigned tag,
206                                                uint64_t default_value);
207
208/* CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from
209 * |cbs|. If present, it sets |*out| to either zero or one, based on the
210 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on
211 * success, whether or not the element was present, and zero on decode
212 * failure. */
213OPENSSL_EXPORT int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag,
214                                              int default_value);
215
216
217/* CRYPTO ByteBuilder.
218 *
219 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB|
220 * object is associated with a buffer and new buffers are created with
221 * |CBB_init|. Several |CBB| objects can point at the same buffer when a
222 * length-prefix is pending, however only a single |CBB| can be 'current' at
223 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then
224 * the new |CBB| points at the same buffer as the original. But if the original
225 * |CBB| is used then the length prefix is written out and the new |CBB| must
226 * not be used again.
227 *
228 * If one needs to force a length prefix to be written out because a |CBB| is
229 * going out of scope, use |CBB_flush|. */
230
231struct cbb_buffer_st {
232  uint8_t *buf;
233  size_t len;      /* The number of valid bytes. */
234  size_t cap;      /* The size of buf. */
235  char can_resize; /* One iff |buf| is owned by this object. If not then |buf|
236                      cannot be resized. */
237};
238
239struct cbb_st {
240  struct cbb_buffer_st *base;
241  /* child points to a child CBB if a length-prefix is pending. */
242  CBB *child;
243  /* offset is the number of bytes from the start of |base->buf| to this |CBB|'s
244   * pending length prefix. */
245  size_t offset;
246  /* pending_len_len contains the number of bytes in this |CBB|'s pending
247   * length-prefix, or zero if no length-prefix is pending. */
248  uint8_t pending_len_len;
249  char pending_is_asn1;
250  /* is_top_level is true iff this is a top-level |CBB| (as opposed to a child
251   * |CBB|). Top-level objects are valid arguments for |CBB_finish|. */
252  char is_top_level;
253};
254
255/* CBB_zero sets an uninitialised |cbb| to the zero state. It must be
256 * initialised with |CBB_init| or |CBB_init_fixed| before use, but it is safe to
257 * call |CBB_cleanup| without a successful |CBB_init|. This may be used for more
258 * uniform cleanup of a |CBB|. */
259OPENSSL_EXPORT void CBB_zero(CBB *cbb);
260
261/* CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as
262 * needed, the |initial_capacity| is just a hint. It returns one on success or
263 * zero on error. */
264OPENSSL_EXPORT int CBB_init(CBB *cbb, size_t initial_capacity);
265
266/* CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since
267 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB
268 * functions to fail. It returns one on success or zero on error. */
269OPENSSL_EXPORT int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len);
270
271/* CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects
272 * writing to the same buffer. This should be used in an error case where a
273 * serialisation is abandoned.
274 *
275 * This function can only be called on a "top level" |CBB|, i.e. one initialised
276 * with |CBB_init| or |CBB_init_fixed|, or a |CBB| set to the zero state with
277 * |CBB_zero|. */
278OPENSSL_EXPORT void CBB_cleanup(CBB *cbb);
279
280/* CBB_finish completes any pending length prefix and sets |*out_data| to a
281 * malloced buffer and |*out_len| to the length of that buffer. The caller
282 * takes ownership of the buffer and, unless the buffer was fixed with
283 * |CBB_init_fixed|, must call |OPENSSL_free| when done.
284 *
285 * It can only be called on a "top level" |CBB|, i.e. one initialised with
286 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on
287 * error. */
288OPENSSL_EXPORT int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len);
289
290/* CBB_flush causes any pending length prefixes to be written out and any child
291 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero
292 * on error. */
293OPENSSL_EXPORT int CBB_flush(CBB *cbb);
294
295/* CBB_data returns a pointer to the bytes written to |cbb|. It does not flush
296 * |cbb|. The pointer is valid until the next operation to |cbb|.
297 *
298 * To avoid unfinalized length prefixes, it is a fatal error to call this on a
299 * CBB with any active children. */
300OPENSSL_EXPORT const uint8_t *CBB_data(const CBB *cbb);
301
302/* CBB_len returns the number of bytes written to |cbb|. It does not flush
303 * |cbb|.
304 *
305 * To avoid unfinalized length prefixes, it is a fatal error to call this on a
306 * CBB with any active children. */
307OPENSSL_EXPORT size_t CBB_len(const CBB *cbb);
308
309/* CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The
310 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit
311 * length. It returns one on success or zero on error. */
312OPENSSL_EXPORT int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents);
313
314/* CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|.
315 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit,
316 * big-endian length. It returns one on success or zero on error. */
317OPENSSL_EXPORT int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents);
318
319/* CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|.
320 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit,
321 * big-endian length. It returns one on success or zero on error. */
322OPENSSL_EXPORT int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents);
323
324/* CBB_add_asn1 sets |*out_contents| to a |CBB| into which the contents of an
325 * ASN.1 object can be written. The |tag| argument will be used as the tag for
326 * the object. Passing in |tag| number 31 will return in an error since only
327 * single octet identifiers are supported. It returns one on success or zero
328 * on error. */
329OPENSSL_EXPORT int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag);
330
331/* CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on
332 * success and zero otherwise. */
333OPENSSL_EXPORT int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len);
334
335/* CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to
336 * the beginning of that space. The caller must then write |len| bytes of
337 * actual contents to |*out_data|. It returns one on success and zero
338 * otherwise. */
339OPENSSL_EXPORT int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len);
340
341/* CBB_reserve ensures |cbb| has room for |len| additional bytes and sets
342 * |*out_data| to point to the beginning of that space. It returns one on
343 * success and zero otherwise. The caller may write up to |len| bytes to
344 * |*out_data| and call |CBB_did_write| to complete the write. |*out_data| is
345 * valid until the next operation on |cbb| or an ancestor |CBB|. */
346OPENSSL_EXPORT int CBB_reserve(CBB *cbb, uint8_t **out_data, size_t len);
347
348/* CBB_did_write advances |cbb| by |len| bytes, assuming the space has been
349 * written to by the caller. It returns one on success and zero on error. */
350OPENSSL_EXPORT int CBB_did_write(CBB *cbb, size_t len);
351
352/* CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on
353 * success and zero otherwise. */
354OPENSSL_EXPORT int CBB_add_u8(CBB *cbb, uint8_t value);
355
356/* CBB_add_u16 appends a 16-bit, big-endian number from |value| to |cbb|. It
357 * returns one on success and zero otherwise. */
358OPENSSL_EXPORT int CBB_add_u16(CBB *cbb, uint16_t value);
359
360/* CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It
361 * returns one on success and zero otherwise. */
362OPENSSL_EXPORT int CBB_add_u24(CBB *cbb, uint32_t value);
363
364/* CBB_discard_child discards the current unflushed child of |cbb|. Neither the
365 * child's contents nor the length prefix will be included in the output. */
366OPENSSL_EXPORT void CBB_discard_child(CBB *cbb);
367
368/* CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1|
369 * and writes |value| in its contents. It returns one on success and zero on
370 * error. */
371OPENSSL_EXPORT int CBB_add_asn1_uint64(CBB *cbb, uint64_t value);
372
373
374#if defined(__cplusplus)
375}  /* extern C */
376#endif
377
378#endif  /* OPENSSL_HEADER_BYTESTRING_H */
379