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) 21 extern "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 37 struct 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|. */ 44 OPENSSL_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. */ 48 OPENSSL_EXPORT int CBS_skip(CBS *cbs, size_t len); 49 50 /* CBS_data returns a pointer to the contains of |cbs|. */ 51 OPENSSL_EXPORT const uint8_t *CBS_data(const CBS *cbs); 52 53 /* CBS_len returns the number of bytes remaining in |cbs|. */ 54 OPENSSL_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. */ 61 OPENSSL_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. */ 70 OPENSSL_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. */ 74 OPENSSL_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. */ 79 OPENSSL_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. */ 84 OPENSSL_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. */ 88 OPENSSL_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. */ 92 OPENSSL_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. */ 96 OPENSSL_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. */ 100 OPENSSL_EXPORT int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 101 102 /* CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 103 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 104 * on success and zero on error. */ 105 OPENSSL_EXPORT int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 106 107 /* CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 108 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 109 * returns one on success and zero on error. */ 110 OPENSSL_EXPORT int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 111 112 /* CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 113 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 114 * returns one on success and zero on error. */ 115 OPENSSL_EXPORT int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 116 117 118 /* Parsing ASN.1 */ 119 120 #define CBS_ASN1_BOOLEAN 0x1 121 #define CBS_ASN1_INTEGER 0x2 122 #define CBS_ASN1_BITSTRING 0x3 123 #define CBS_ASN1_OCTETSTRING 0x4 124 #define CBS_ASN1_OBJECT 0x6 125 #define CBS_ASN1_ENUMERATED 0xa 126 #define CBS_ASN1_SEQUENCE (0x10 | CBS_ASN1_CONSTRUCTED) 127 #define CBS_ASN1_SET (0x11 | CBS_ASN1_CONSTRUCTED) 128 129 #define CBS_ASN1_CONSTRUCTED 0x20 130 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 131 132 /* CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 133 * including tag and length bytes) and advances |cbs| over it. The ASN.1 134 * element must match |tag_value|. It returns one on success and zero 135 * on error. 136 * 137 * Tag numbers greater than 31 are not supported. */ 138 OPENSSL_EXPORT int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value); 139 140 /* CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 141 * ASN.1 header bytes too. */ 142 OPENSSL_EXPORT int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value); 143 144 /* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 145 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 146 * the tag number and |*out_header_len| to the length of the ASN.1 header. If 147 * the element has indefinite length then |*out| will only contain the 148 * header. Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore 149 * the value. 150 * 151 * Tag numbers greater than 31 are not supported. */ 152 OPENSSL_EXPORT int CBS_get_any_asn1_element(CBS *cbs, CBS *out, 153 unsigned *out_tag, 154 size_t *out_header_len); 155 156 /* CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 157 * and sets |*out| to its value. It returns one on success and zero on error, 158 * where error includes the integer being negative, or too large to represent 159 * in 64 bits. */ 160 OPENSSL_EXPORT int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 161 162 163 /* CRYPTO ByteBuilder. 164 * 165 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 166 * object is associated with a buffer and new buffers are created with 167 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 168 * length-prefix is pending, however only a single |CBB| can be 'current' at 169 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 170 * the new |CBB| points at the same buffer as the original. But if the original 171 * |CBB| is used then the length prefix is written out and the new |CBB| must 172 * not be used again. 173 * 174 * If one needs to force a length prefix to be written out because a |CBB| is 175 * going out of scope, use |CBB_flush|. */ 176 177 struct cbb_buffer_st { 178 uint8_t *buf; 179 size_t len; /* The number of valid bytes. */ 180 size_t cap; /* The size of buf. */ 181 char can_resize; /* One iff |buf| is owned by this object. If not then |buf| 182 cannot be resized. */ 183 }; 184 185 struct cbb_st { 186 struct cbb_buffer_st *base; 187 /* offset is the offset from the start of |base->buf| to the position of any 188 * pending length-prefix. */ 189 size_t offset; 190 /* child points to a child CBB if a length-prefix is pending. */ 191 struct cbb_st *child; 192 /* pending_len_len contains the number of bytes in a pending length-prefix, 193 * or zero if no length-prefix is pending. */ 194 uint8_t pending_len_len; 195 char pending_is_asn1; 196 /* is_top_level is true iff this is a top-level |CBB| (as opposed to a child 197 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. */ 198 char is_top_level; 199 }; 200 201 /* CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 202 * needed, the |initial_capacity| is just a hint. It returns one on success or 203 * zero on error. */ 204 OPENSSL_EXPORT int CBB_init(CBB *cbb, size_t initial_capacity); 205 206 /* CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 207 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 208 * functions to fail. It returns one on success or zero on error. */ 209 OPENSSL_EXPORT int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 210 211 /* CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 212 * writing to the same buffer. This should be used in an error case where a 213 * serialisation is abandoned. */ 214 OPENSSL_EXPORT void CBB_cleanup(CBB *cbb); 215 216 /* CBB_finish completes any pending length prefix and sets |*out_data| to a 217 * malloced buffer and |*out_len| to the length of that buffer. The caller 218 * takes ownership of the buffer and, unless the buffer was fixed with 219 * |CBB_init_fixed|, must call |OPENSSL_free| when done. 220 * 221 * It can only be called on a "top level" |CBB|, i.e. one initialised with 222 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 223 * error. */ 224 OPENSSL_EXPORT int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 225 226 /* CBB_flush causes any pending length prefixes to be written out and any child 227 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 228 * on error. */ 229 OPENSSL_EXPORT int CBB_flush(CBB *cbb); 230 231 /* CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 232 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 233 * length. It returns one on success or zero on error. */ 234 OPENSSL_EXPORT int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 235 236 /* CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 237 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 238 * big-endian length. It returns one on success or zero on error. */ 239 OPENSSL_EXPORT int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 240 241 /* CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 242 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 243 * big-endian length. It returns one on success or zero on error. */ 244 OPENSSL_EXPORT int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 245 246 /* CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 247 * ASN.1 object can be written. The |tag| argument will be used as the tag for 248 * the object. It returns one on success or zero on error. */ 249 OPENSSL_EXPORT int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag); 250 251 /* CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 252 * success and zero otherwise. */ 253 OPENSSL_EXPORT int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 254 255 /* CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 256 * the beginning of that space. The caller must then write |len| bytes of 257 * actual contents to |*out_data|. It returns one on success and zero 258 * otherwise. */ 259 OPENSSL_EXPORT int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 260 261 /* CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 262 * success and zero otherwise. */ 263 OPENSSL_EXPORT int CBB_add_u8(CBB *cbb, uint8_t value); 264 265 /* CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 266 * returns one on success and zero otherwise. */ 267 OPENSSL_EXPORT int CBB_add_u16(CBB *cbb, uint16_t value); 268 269 /* CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 270 * returns one on success and zero otherwise. */ 271 OPENSSL_EXPORT int CBB_add_u24(CBB *cbb, uint32_t value); 272 273 274 #if defined(__cplusplus) 275 } /* extern C */ 276 #endif 277 278 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 279
