/* $OpenBSD: bytestring.h,v 1.25 2024/06/22 15:25:06 jsing Exp $ */ /* * Copyright (c) 2014, Google Inc. * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #ifndef OPENSSL_HEADER_BYTESTRING_H #define OPENSSL_HEADER_BYTESTRING_H #include #include __BEGIN_HIDDEN_DECLS /* * Bytestrings are used for parsing and building TLS and ASN.1 messages. * * A "CBS" (CRYPTO ByteString) represents a string of bytes in memory and * provides utility functions for safely parsing length-prefixed structures * like TLS and ASN.1 from it. * * A "CBB" (CRYPTO ByteBuilder) is a memory buffer that grows as needed and * provides utility functions for building length-prefixed messages. */ /* CRYPTO ByteString */ typedef struct cbs_st { const uint8_t *data; size_t initial_len; size_t len; } CBS; /* * CBS_init sets |cbs| to point to |data|. It does not take ownership of * |data|. */ void CBS_init(CBS *cbs, const uint8_t *data, size_t len); /* * CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero * otherwise. */ int CBS_skip(CBS *cbs, size_t len); /* * CBS_data returns a pointer to the contents of |cbs|. */ const uint8_t *CBS_data(const CBS *cbs); /* * CBS_len returns the number of bytes remaining in |cbs|. */ size_t CBS_len(const CBS *cbs); /* * CBS_offset returns the current offset into the original data of |cbs|. */ size_t CBS_offset(const CBS *cbs); /* * CBS_stow copies the current contents of |cbs| into |*out_ptr| and * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with * free. It returns one on success and zero on allocation failure. On * success, |*out_ptr| should be freed with free. If |cbs| is empty, * |*out_ptr| will be NULL. */ int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len); /* * CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed * with free. It returns one on success and zero on failure. On success, * |*out_ptr| should be freed with free. If |cbs| contains NUL bytes, * CBS_strdup will fail. */ int CBS_strdup(const CBS *cbs, char **out_ptr); /* * CBS_write_bytes writes all of the remaining data from |cbs| into |dst| * if it is at most |dst_len| bytes. If |copied| is not NULL, it will be set * to the amount copied. It returns one on success and zero otherwise. */ int CBS_write_bytes(const CBS *cbs, uint8_t *dst, size_t dst_len, size_t *copied); /* * CBS_contains_zero_byte returns one if the current contents of |cbs| contains * a NUL byte and zero otherwise. */ int CBS_contains_zero_byte(const CBS *cbs); /* * CBS_mem_equal compares the current contents of |cbs| with the |len| bytes * starting at |data|. If they're equal, it returns one, otherwise zero. If the * lengths match, it uses a constant-time comparison. */ int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len); /* * CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It * returns one on success and zero on error. */ int CBS_get_u8(CBS *cbs, uint8_t *out); /* * CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and * advances |cbs|. It returns one on success and zero on error. */ int CBS_get_u16(CBS *cbs, uint16_t *out); /* * CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and * advances |cbs|. It returns one on success and zero on error. */ int CBS_get_u24(CBS *cbs, uint32_t *out); /* * CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs| * and advances |cbs|. It returns one on success and zero on error. */ int CBS_get_u32(CBS *cbs, uint32_t *out); /* * CBS_get_u64 sets |*out| to the next, big-endian uint64_t value from |cbs| * and advances |cbs|. It returns one on success and zero on error. */ int CBS_get_u64(CBS *cbs, uint64_t *out); /* * CBS_get_last_u8 sets |*out| to the last uint8_t from |cbs| and shortens * |cbs|. It returns one on success and zero on error. */ int CBS_get_last_u8(CBS *cbs, uint8_t *out); /* * CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances * |cbs|. It returns one on success and zero on error. */ int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); /* * CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, * length-prefixed value from |cbs| and advances |cbs| over it. It returns one * on success and zero on error. */ int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); /* * CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It * returns one on success and zero on error. */ int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); /* * CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It * returns one on success and zero on error. */ int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); /* * CBS_peek_u8 sets |*out| to the next uint8_t from |cbs|, but does not advance * |cbs|. It returns one on success and zero on error. */ int CBS_peek_u8(CBS *cbs, uint8_t *out); /* * CBS_peek_u16 sets |*out| to the next, big-endian uint16_t from |cbs|, but * does not advance |cbs|. It returns one on success and zero on error. */ int CBS_peek_u16(CBS *cbs, uint16_t *out); /* * CBS_peek_u24 sets |*out| to the next, big-endian 24-bit value from |cbs|, but * does not advance |cbs|. It returns one on success and zero on error. */ int CBS_peek_u24(CBS *cbs, uint32_t *out); /* * CBS_peek_u32 sets |*out| to the next, big-endian uint32_t value from |cbs|, * but does not advance |cbs|. It returns one on success and zero on error. */ int CBS_peek_u32(CBS *cbs, uint32_t *out); /* * CBS_peek_last_u8 sets |*out| to the last uint8_t from |cbs|, but does not * shorten |cbs|. It returns one on success and zero on error. */ int CBS_peek_last_u8(CBS *cbs, uint8_t *out); /* Parsing ASN.1 */ /* * While an identifier can be multiple octets, this library only handles the * single octet variety currently. This limits support up to tag number 30 * since tag number 31 is a reserved value to indicate multiple octets. */ /* Bits 8 and 7: class tag type: See X.690 section 8.1.2.2. */ #define CBS_ASN1_UNIVERSAL 0x00 #define CBS_ASN1_APPLICATION 0x40 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 #define CBS_ASN1_PRIVATE 0xc0 /* Bit 6: Primitive or constructed: See X.690 section 8.1.2.3. */ #define CBS_ASN1_PRIMITIVE 0x00 #define CBS_ASN1_CONSTRUCTED 0x20 /* * Bits 5 to 1 are the tag number. See X.680 section 8.6 for tag numbers of * the universal class. */ /* * Common universal identifier octets. * See X.690 section 8.1 and X.680 section 8.6 for universal tag numbers. * * Note: These definitions are the cause of some of the strange behavior in * CBS's bs_ber.c. * * In BER, it is the sender's option to use primitive or constructed for * bitstring (X.690 section 8.6.1) and octetstring (X.690 section 8.7.1). * * In DER, bitstring and octetstring are required to be primitive * (X.690 section 10.2). */ #define CBS_ASN1_BOOLEAN (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x1) #define CBS_ASN1_INTEGER (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x2) #define CBS_ASN1_BITSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x3) #define CBS_ASN1_OCTETSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x4) #define CBS_ASN1_OBJECT (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x6) #define CBS_ASN1_ENUMERATED (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0xa) #define CBS_ASN1_SEQUENCE (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x10) #define CBS_ASN1_SET (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x11) /* * CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not * including tag and length bytes) and advances |cbs| over it. The ASN.1 * element must match |tag_value|. It returns one on success and zero * on error. * * Tag numbers greater than 30 are not supported (i.e. short form only). */ int CBS_get_asn1(CBS *cbs, CBS *out, unsigned int tag_value); /* * CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the * ASN.1 header bytes too. */ int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned int tag_value); /* * CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one * if the next ASN.1 element on |cbs| would have tag |tag_value|. If * |cbs| is empty or the tag does not match, it returns zero. Note: if * it returns one, CBS_get_asn1 may still fail if the rest of the * element is malformed. */ int CBS_peek_asn1_tag(const CBS *cbs, unsigned int tag_value); /* * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to * the tag number and |*out_header_len| to the length of the ASN.1 header. * Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore * the value. * * Tag numbers greater than 30 are not supported (i.e. short form only). */ int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned int *out_tag, size_t *out_header_len); /* * CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| * and sets |*out| to its value. It returns one on success and zero on error, * where error includes the integer being negative, or too large to represent * in 64 bits. */ int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); /* * CBS_get_optional_asn1 gets an optional explicitly-tagged element * from |cbs| tagged with |tag| and sets |*out| to its contents. If * present, it sets |*out_present| to one, otherwise zero. It returns * one on success, whether or not the element was present, and zero on * decode failure. */ int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned int tag); /* * CBS_get_optional_asn1_octet_string gets an optional * explicitly-tagged OCTET STRING from |cbs|. If present, it sets * |*out| to the string and |*out_present| to one. Otherwise, it sets * |*out| to empty and |*out_present| to zero. |out_present| may be * NULL. It returns one on success, whether or not the element was * present, and zero on decode failure. */ int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, unsigned int tag); /* * CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged * INTEGER from |cbs|. If present, it sets |*out| to the * value. Otherwise, it sets |*out| to |default_value|. It returns one * on success, whether or not the element was present, and zero on * decode failure. */ int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned int tag, uint64_t default_value); /* * CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from * |cbs|. If present, it sets |*out| to either zero or one, based on the * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on * success, whether or not the element was present, and zero on decode * failure. */ int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned int tag, int default_value); /* * CRYPTO ByteBuilder. * * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| * object is associated with a buffer and new buffers are created with * |CBB_init|. Several |CBB| objects can point at the same buffer when a * length-prefix is pending, however only a single |CBB| can be 'current' at * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then * the new |CBB| points at the same buffer as the original. But if the original * |CBB| is used then the length prefix is written out and the new |CBB| must * not be used again. * * If one needs to force a length prefix to be written out because a |CBB| is * going out of scope, use |CBB_flush|. */ struct cbb_buffer_st { uint8_t *buf; /* The number of valid bytes. */ size_t len; /* The size of buf. */ size_t cap; /* * One iff |buf| is owned by this object. If not then |buf| cannot be * resized. */ char can_resize; }; typedef struct cbb_st { struct cbb_buffer_st *base; /* * offset is the offset from the start of |base->buf| to the position of any * pending length-prefix. */ size_t offset; /* child points to a child CBB if a length-prefix is pending. */ struct cbb_st *child; /* * pending_len_len contains the number of bytes in a pending length-prefix, * or zero if no length-prefix is pending. */ uint8_t pending_len_len; char pending_is_asn1; /* * is_top_level is true iff this is a top-level |CBB| (as opposed to a child * |CBB|). Top-level objects are valid arguments for |CBB_finish|. */ char is_top_level; } CBB; /* * CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as * needed, the |initial_capacity| is just a hint. It returns one on success or * zero on error. */ int CBB_init(CBB *cbb, size_t initial_capacity); /* * CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since * |buf| cannot grow, trying to write more than |len| bytes will cause CBB * functions to fail. It returns one on success or zero on error. */ int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); /* * CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects * writing to the same buffer. This should be used in an error case where a * serialisation is abandoned. */ void CBB_cleanup(CBB *cbb); /* * CBB_finish completes any pending length prefix and sets |*out_data| to a * malloced buffer and |*out_len| to the length of that buffer. The caller * takes ownership of the buffer and, unless the buffer was fixed with * |CBB_init_fixed|, must call |free| when done. * * It can only be called on a "top level" |CBB|, i.e. one initialised with * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on * error. */ int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); /* * CBB_flush causes any pending length prefixes to be written out and any child * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero * on error. */ int CBB_flush(CBB *cbb); /* * CBB_discard_child discards the current unflushed child of |cbb|. Neither the * child's contents nor the length prefix will be included in the output. */ void CBB_discard_child(CBB *cbb); /* * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit * length. It returns one on success or zero on error. */ int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); /* * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, * big-endian length. It returns one on success or zero on error. */ int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); /* * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, * big-endian length. It returns one on success or zero on error. */ int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); /* * CBB_add_u32_length_prefixed sets |*out_contents| to a new child of |cbb|. * The data written to |*out_contents| will be prefixed in |cbb| with a 32-bit, * big-endian length. It returns one on success or zero on error. */ int CBB_add_u32_length_prefixed(CBB *cbb, CBB *out_contents); /* * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an * ASN.1 object can be written. The |tag| argument will be used as the tag for * the object. Passing in |tag| number 31 will return in an error since only * single octet identifiers are supported. It returns one on success or zero * on error. */ int CBB_add_asn1(CBB *cbb, CBB *out_contents, unsigned int tag); /* * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on * success and zero otherwise. */ int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); /* * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to * the beginning of that space. The caller must then write |len| bytes of * actual contents to |*out_data|. It returns one on success and zero * otherwise. */ int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); /* * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on * success and zero otherwise. */ int CBB_add_u8(CBB *cbb, size_t value); /* * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It * returns one on success and zero otherwise. */ int CBB_add_u16(CBB *cbb, size_t value); /* * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It * returns one on success and zero otherwise. */ int CBB_add_u24(CBB *cbb, size_t value); /* * CBB_add_u32 appends a 32-bit, big-endian number from |value| to |cbb|. It * returns one on success and zero otherwise. */ int CBB_add_u32(CBB *cbb, size_t value); /* * CBB_add_u64 appends a 64-bit, big-endian number from |value| to |cbb|. It * returns one on success and zero otherwise. */ int CBB_add_u64(CBB *cbb, uint64_t value); /* * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| * and writes |value| in its contents. It returns one on success and zero on * error. */ int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); #ifdef LIBRESSL_INTERNAL /* * CBS_dup sets |out| to point to cbs's |data| and |len|. It results in two * CBS that point to the same buffer. */ void CBS_dup(const CBS *cbs, CBS *out); /* * cbs_get_any_asn1_element sets |*out| to contain the next ASN.1 element from * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to * the tag number and |*out_header_len| to the length of the ASN.1 header. If * strict mode is disabled and the element has indefinite length then |*out| * will only contain the header. Each of |out|, |out_tag|, and * |out_header_len| may be NULL to ignore the value. * * Tag numbers greater than 30 are not supported (i.e. short form only). */ int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned int *out_tag, size_t *out_header_len, int strict); /* * CBS_asn1_indefinite_to_definite reads an ASN.1 structure from |in|. If it * finds indefinite-length elements that otherwise appear to be valid DER, it * attempts to convert the DER-like data to DER and sets |*out| and * |*out_length| to describe a malloced buffer containing the DER data. * Additionally, |*in| will be advanced over the ASN.1 data. * * If it doesn't find any indefinite-length elements then it sets |*out| to * NULL and |*in| is unmodified. * * This is NOT a conversion from BER to DER. There are many restrictions when * dealing with DER data. This is only concerned with one: indefinite vs. * definite form. However, this suffices to handle the PKCS#7 and PKCS#12 output * from NSS. * * It returns one on success and zero otherwise. */ int CBS_asn1_indefinite_to_definite(CBS *in, uint8_t **out, size_t *out_len); #endif /* LIBRESSL_INTERNAL */ __END_HIDDEN_DECLS #endif /* OPENSSL_HEADER_BYTESTRING_H */