Import BoringSSL's crypto bytestring and crypto bytebuilder APIs.

This is imported with as few changes as possible for the initial commit.
I removed OPENSSL_EXPORT, replaced OPENSSL_malloc() etc with malloc()
and changed a few header includes.

BoringSSL has this as part of their public API.  We're leaving it internal
to libssl for now.

Based on BoringSSL's CBB/CBS API as of commit
c5cc15b4f5b1d6e9b9112cb8d30205a638aa2c54.

input + ok jsing@, miod@

1 files changed, 346 insertions, 0 deletions

diff --git a/src/lib/libssl/bytestring.h b/src/lib/libssl/bytestring.h
new file mode 100644
index 0000000000..3c4e8eaaf3
--- /dev/null
+++ b/src/lib/libssl/bytestring.h
@@ -0,0 +1,346 @@
+/*      $OpenBSD: bytestring.h,v 1.1 2015/02/06 09:36:16 doug 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
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#include <sys/types.h>
+#include <stdint.h>
+
+#include <openssl/opensslconf.h>
+
+/* 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 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 contains 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_stow copies the current contents of |cbs| into |*out_ptr| and
+ * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with
+ * OPENSSL_free. It returns one on success and zero on allocation failure. On
+ * success, |*out_ptr| should be freed with OPENSSL_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 OPENSSL_free. It returns one on success and zero on allocation
+ * failure. On success, |*out_ptr| should be freed with OPENSSL_free.
+ *
+ * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call
+ * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. */
+int CBS_strdup(const CBS *cbs, char **out_ptr);
+
+/* 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_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);
+
+
+/* Parsing ASN.1 */
+
+#define CBS_ASN1_BOOLEAN 0x1
+#define CBS_ASN1_INTEGER 0x2
+#define CBS_ASN1_BITSTRING 0x3
+#define CBS_ASN1_OCTETSTRING 0x4
+#define CBS_ASN1_OBJECT 0x6
+#define CBS_ASN1_ENUMERATED 0xa
+#define CBS_ASN1_SEQUENCE (0x10 | CBS_ASN1_CONSTRUCTED)
+#define CBS_ASN1_SET (0x11 | CBS_ASN1_CONSTRUCTED)
+
+#define CBS_ASN1_CONSTRUCTED 0x20
+#define CBS_ASN1_CONTEXT_SPECIFIC 0x80
+
+/* 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 31 are not supported. */
+int CBS_get_asn1(CBS *cbs, CBS *out, unsigned 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 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 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. If
+ * 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 31 are not supported. */
+int CBS_get_any_asn1_element(CBS *cbs, CBS *out,
+                                            unsigned *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 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 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 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 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;
+  size_t len;      /* The number of valid bytes. */
+  size_t cap;      /* The size of buf. */
+  char can_resize; /* One iff |buf| is owned by this object. If not then |buf|
+                      cannot be resized. */
+};
+
+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 |OPENSSL_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_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_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. It returns one on success or zero on error. */
+int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t 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, uint8_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, uint16_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, uint32_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_asn1_ber_to_der reads an ASN.1 structure from |in|. If it finds
+ * indefinite-length elements then it attempts to convert the BER 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.
+ *
+ * A sufficiently complex ASN.1 structure will break this function because it's
+ * not possible to generically convert BER to DER without knowledge of the
+ * structure itself. However, this sufficies to handle the PKCS#7 and #12 output
+ * from NSS.
+ *
+ * It returns one on success and zero otherwise. */
+int CBS_asn1_ber_to_der(CBS *in, uint8_t **out, size_t *out_len);
+#endif /* LIBRESSL_INTERNAL */
+
+#if defined(__cplusplus)
+}  /* extern C */
+#endif
+
+#endif  /* OPENSSL_HEADER_BYTESTRING_H */