IABSD.fr/src/lib/libssl/bs_cbb.c

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• Author : beck
  Date : 2019-01-23 22:20:40
  Hash : 59f50346
  Message : assert.h is often misused. It should not be used in a library ok bcook@ jsing@

• lib/libssl/bs_cbb.c

• /*	$OpenBSD: bs_cbb.c,v 1.20 2019/01/23 22:20:40 beck 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. */
  
  #include <stdlib.h>
  #include <string.h>
  
  #include <openssl/opensslconf.h>
  
  #include "bytestring.h"
  
  #define CBB_INITIAL_SIZE 64
  
  static int
  cbb_init(CBB *cbb, uint8_t *buf, size_t cap)
  {
  	struct cbb_buffer_st *base;
  
  	base = malloc(sizeof(struct cbb_buffer_st));
  	if (base == NULL)
  		return 0;
  
  	base->buf = buf;
  	base->len = 0;
  	base->cap = cap;
  	base->can_resize = 1;
  
  	cbb->base = base;
  	cbb->is_top_level = 1;
  
  	return 1;
  }
  
  int
  CBB_init(CBB *cbb, size_t initial_capacity)
  {
  	uint8_t *buf = NULL;
  
  	memset(cbb, 0, sizeof(*cbb));
  
  	if (initial_capacity == 0)
  		initial_capacity = CBB_INITIAL_SIZE;
  
  	if ((buf = malloc(initial_capacity)) == NULL)
  		return 0;
  
  	if (!cbb_init(cbb, buf, initial_capacity)) {
  		free(buf);
  		return 0;
  	}
  
  	return 1;
  }
  
  int
  CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len)
  {
  	memset(cbb, 0, sizeof(*cbb));
  
  	if (!cbb_init(cbb, buf, len))
  		return 0;
  
  	cbb->base->can_resize = 0;
  
  	return 1;
  }
  
  void
  CBB_cleanup(CBB *cbb)
  {
  	if (cbb->base) {
  		if (cbb->base->can_resize)
  			freezero(cbb->base->buf, cbb->base->cap);
  		free(cbb->base);
  	}
  	cbb->base = NULL;
  	cbb->child = NULL;
  }
  
  static int
  cbb_buffer_add(struct cbb_buffer_st *base, uint8_t **out, size_t len)
  {
  	size_t newlen;
  
  	if (base == NULL)
  		return 0;
  
  	newlen = base->len + len;
  	if (newlen < base->len)
  		/* Overflow */
  		return 0;
  
  	if (newlen > base->cap) {
  		size_t newcap = base->cap * 2;
  		uint8_t *newbuf;
  
  		if (!base->can_resize)
  			return 0;
  
  		if (newcap < base->cap || newcap < newlen)
  			newcap = newlen;
  
  		newbuf = recallocarray(base->buf, base->cap, newcap, 1);
  		if (newbuf == NULL)
  			return 0;
  
  		base->buf = newbuf;
  		base->cap = newcap;
  	}
  
  	if (out)
  		*out = base->buf + base->len;
  
  	base->len = newlen;
  	return 1;
  }
  
  static int
  cbb_add_u(CBB *cbb, uint32_t v, size_t len_len)
  {
  	uint8_t *buf;
  	size_t i;
  
  	if (len_len == 0)
  		return 1;
  
  	if (len_len > 4)
  		return 0;
  
  	if (!CBB_flush(cbb) || !cbb_buffer_add(cbb->base, &buf, len_len))
  		return 0;
  
  	for (i = len_len - 1; i < len_len; i--) {
  		buf[i] = v;
  		v >>= 8;
  	}
  	return 1;
  }
  
  int
  CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len)
  {
  	if (!cbb->is_top_level)
  		return 0;
  
  	if (!CBB_flush(cbb))
  		return 0;
  
  	if (cbb->base->can_resize && (out_data == NULL || out_len == NULL))
  		/*
  		 * |out_data| and |out_len| can only be NULL if the CBB is
  		 * fixed.
  		 */
  		return 0;
  
  	if (out_data != NULL)
  		*out_data = cbb->base->buf;
  
  	if (out_len != NULL)
  		*out_len = cbb->base->len;
  
  	cbb->base->buf = NULL;
  	CBB_cleanup(cbb);
  	return 1;
  }
  
  /*
   * CBB_flush recurses and then writes out any pending length prefix. The current
   * length of the underlying base is taken to be the length of the
   * length-prefixed data.
   */
  int
  CBB_flush(CBB *cbb)
  {
  	size_t child_start, i, len;
  
  	if (cbb->base == NULL)
  		return 0;
  
  	if (cbb->child == NULL || cbb->pending_len_len == 0)
  		return 1;
  
  	child_start = cbb->offset + cbb->pending_len_len;
  
  	if (!CBB_flush(cbb->child) || child_start < cbb->offset ||
  	    cbb->base->len < child_start)
  		return 0;
  
  	len = cbb->base->len - child_start;
  
  	if (cbb->pending_is_asn1) {
  		/*
  		 * For ASN.1, we assumed that we were using short form which
  		 * only requires a single byte for the length octet.
  		 *
  		 * If it turns out that we need long form, we have to move
  		 * the contents along in order to make space for more length
  		 * octets.
  		 */
  		size_t len_len = 1;  /* total number of length octets */
  		uint8_t initial_length_byte;
  
  		/* We already wrote 1 byte for the length. */
  		if (cbb->pending_len_len != 1)
  			return 0;
  
  		/* Check for long form */
  		if (len > 0xfffffffe)
  			return 0;	/* 0xffffffff is reserved */
  		else if (len > 0xffffff)
  			len_len = 5;
  		else if (len > 0xffff)
  			len_len = 4;
  		else if (len > 0xff)
  			len_len = 3;
  		else if (len > 0x7f)
  			len_len = 2;
  
  		if (len_len == 1) {
  			/* For short form, the initial byte is the length. */
  			initial_length_byte = len;
  			len = 0;
  
  		} else {
  			/*
  			 * For long form, the initial byte is the number of
  			 * subsequent length octets (plus bit 8 set).
  			 */
  			initial_length_byte = 0x80 | (len_len - 1);
  
  			/*
  			 * We need to move the contents along in order to make
  			 * space for the long form length octets.
  			 */
  			size_t extra_bytes = len_len - 1;
  			if (!cbb_buffer_add(cbb->base, NULL, extra_bytes))
  				return 0;
  
  			memmove(cbb->base->buf + child_start + extra_bytes,
  			    cbb->base->buf + child_start, len);
  		}
  		cbb->base->buf[cbb->offset++] = initial_length_byte;
  		cbb->pending_len_len = len_len - 1;
  	}
  
  	for (i = cbb->pending_len_len - 1; i < cbb->pending_len_len; i--) {
  		cbb->base->buf[cbb->offset + i] = len;
  		len >>= 8;
  	}
  	if (len != 0)
  		return 0;
  
  	cbb->child->base = NULL;
  	cbb->child = NULL;
  	cbb->pending_len_len = 0;
  	cbb->pending_is_asn1 = 0;
  	cbb->offset = 0;
  
  	return 1;
  }
  
  void
  CBB_discard_child(CBB *cbb)
  {
  	if (cbb->child == NULL)
  		return;
  
  	cbb->base->len = cbb->offset;
  	
  	cbb->child->base = NULL;
  	cbb->child = NULL;
  	cbb->pending_len_len = 0;
  	cbb->pending_is_asn1 = 0;
  	cbb->offset = 0;
  }
  
  static int
  cbb_add_length_prefixed(CBB *cbb, CBB *out_contents, size_t len_len)
  {
  	uint8_t *prefix_bytes;
  
  	if (!CBB_flush(cbb))
  		return 0;
  
  	cbb->offset = cbb->base->len;
  	if (!cbb_buffer_add(cbb->base, &prefix_bytes, len_len))
  		return 0;
  
  	memset(prefix_bytes, 0, len_len);
  	memset(out_contents, 0, sizeof(CBB));
  	out_contents->base = cbb->base;
  	cbb->child = out_contents;
  	cbb->pending_len_len = len_len;
  	cbb->pending_is_asn1 = 0;
  
  	return 1;
  }
  
  int
  CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents)
  {
  	return cbb_add_length_prefixed(cbb, out_contents, 1);
  }
  
  int
  CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents)
  {
  	return cbb_add_length_prefixed(cbb, out_contents, 2);
  }
  
  int
  CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents)
  {
  	return cbb_add_length_prefixed(cbb, out_contents, 3);
  }
  
  int
  CBB_add_asn1(CBB *cbb, CBB *out_contents, unsigned int tag)
  {
  	if (tag > UINT8_MAX)
  		return 0;
  
  	/* Long form identifier octets are not supported. */
  	if ((tag & 0x1f) == 0x1f)
  		return 0;
  
  	/* Short-form identifier octet only needs a single byte */
  	if (!CBB_flush(cbb) || !CBB_add_u8(cbb, tag))
  		return 0;
  
  	/*
  	 * Add 1 byte to cover the short-form length octet case.  If it turns
  	 * out we need long-form, it will be extended later.
  	 */
  	cbb->offset = cbb->base->len;
  	if (!CBB_add_u8(cbb, 0))
  		return 0;
  
  	memset(out_contents, 0, sizeof(CBB));
  	out_contents->base = cbb->base;
  	cbb->child = out_contents;
  	cbb->pending_len_len = 1;
  	cbb->pending_is_asn1 = 1;
  
  	return 1;
  }
  
  int
  CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len)
  {
  	uint8_t *dest;
  
  	if (!CBB_add_space(cbb, &dest, len))
  		return 0;
  
  	memcpy(dest, data, len);
  	return 1;
  }
  
  int
  CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len)
  {
  	if (!CBB_flush(cbb) || !cbb_buffer_add(cbb->base, out_data, len))
  		return 0;
  
  	return 1;
  }
  
  int
  CBB_add_u8(CBB *cbb, size_t value)
  {
  	if (value > UINT8_MAX)
  		return 0;
  
  	return cbb_add_u(cbb, (uint32_t)value, 1);
  }
  
  int
  CBB_add_u16(CBB *cbb, size_t value)
  {
  	if (value > UINT16_MAX)
  		return 0;
  
  	return cbb_add_u(cbb, (uint32_t)value, 2);
  }
  
  int
  CBB_add_u24(CBB *cbb, size_t value)
  {
  	if (value > 0xffffffUL)
  		return 0;
  
  	return cbb_add_u(cbb, (uint32_t)value, 3);
  }
  
  int
  CBB_add_u32(CBB *cbb, size_t value)
  {
  	if (value > 0xffffffffUL)
  		return 0;
  
  	return cbb_add_u(cbb, (uint32_t)value, 4);
  }
  
  int
  CBB_add_asn1_uint64(CBB *cbb, uint64_t value)
  {
  	CBB child;
  	size_t i;
  	int started = 0;
  
  	if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER))
  		return 0;
  
  	for (i = 0; i < 8; i++) {
  		uint8_t byte = (value >> 8 * (7 - i)) & 0xff;
  
  		/*
  		 * ASN.1 restriction: first 9 bits cannot be all zeroes or
  		 * all ones.  Since this function only encodes unsigned
  		 * integers, the only concerns are not encoding leading
  		 * zeros and adding a padding byte if necessary.
  		 *
  		 * In practice, this means:
  		 * 1) Skip leading octets of all zero bits in the value
  		 * 2) After skipping the leading zero octets, if the next 9
  		 *    bits are all ones, add an all zero prefix octet (and
  		 *    set the high bit of the prefix octet if negative).
  		 *
  		 * Additionally, for an unsigned value, add an all zero
  		 * prefix if the high bit of the first octet would be one.
  		 */
  		if (!started) {
  			if (byte == 0)
  				/* Don't encode leading zeros. */
  				continue;
  
  			/*
  			 * If the high bit is set, add a padding byte to make it
  			 * unsigned.
  			 */
  			if ((byte & 0x80) && !CBB_add_u8(&child, 0))
  				return 0;
  
  			started = 1;
  		}
  		if (!CBB_add_u8(&child, byte))
  			return 0;
  	}
  
  	/* 0 is encoded as a single 0, not the empty string. */
  	if (!started && !CBB_add_u8(&child, 0))
  		return 0;
  
  	return CBB_flush(cbb);
  }