tasn_dec.c

开源的ssl算法openssl,版本0.9.8H

			free_cont = 1;
			goto err;
			}
		len = buf.length;
		/* Append a final null to string */
		if (!BUF_MEM_grow_clean(&buf, len + 1))
			{
			ASN1err(ASN1_F_ASN1_D2I_EX_PRIMITIVE,
						ERR_R_MALLOC_FAILURE);
			return 0;
			}
		buf.data[len] = 0;
		cont = (const unsigned char *)buf.data;
		free_cont = 1;
		}
	else
		{
		cont = p;
		len = plen;
		p += plen;
		}

	/* We now have content length and type: translate into a structure */
	if (!asn1_ex_c2i(pval, cont, len, utype, &free_cont, it))
		goto err;

	*in = p;
	ret = 1;
	err:
	if (free_cont && buf.data) OPENSSL_free(buf.data);
	return ret;
	}

/* Translate ASN1 content octets into a structure */

int asn1_ex_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
			int utype, char *free_cont, const ASN1_ITEM *it)
	{
	ASN1_VALUE **opval = NULL;
	ASN1_STRING *stmp;
	ASN1_TYPE *typ = NULL;
	int ret = 0;
	const ASN1_PRIMITIVE_FUNCS *pf;
	ASN1_INTEGER **tint;
	pf = it->funcs;

	if (pf && pf->prim_c2i)
		return pf->prim_c2i(pval, cont, len, utype, free_cont, it);
	/* If ANY type clear type and set pointer to internal value */
	if (it->utype == V_ASN1_ANY)
		{
		if (!*pval)
			{
			typ = ASN1_TYPE_new();
			if (typ == NULL)
				goto err;
			*pval = (ASN1_VALUE *)typ;
			}
		else
			typ = (ASN1_TYPE *)*pval;

		if (utype != typ->type)
			ASN1_TYPE_set(typ, utype, NULL);
		opval = pval;
		pval = (ASN1_VALUE **)&typ->value.ptr;
		}
	switch(utype)
		{
		case V_ASN1_OBJECT:
		if (!c2i_ASN1_OBJECT((ASN1_OBJECT **)pval, &cont, len))
			goto err;
		break;

		case V_ASN1_NULL:
		if (len)
			{
			ASN1err(ASN1_F_ASN1_EX_C2I,
						ASN1_R_NULL_IS_WRONG_LENGTH);
			goto err;
			}
		*pval = (ASN1_VALUE *)1;
		break;

		case V_ASN1_BOOLEAN:
		if (len != 1)
			{
			ASN1err(ASN1_F_ASN1_EX_C2I,
						ASN1_R_BOOLEAN_IS_WRONG_LENGTH);
			goto err;
			}
		else
			{
			ASN1_BOOLEAN *tbool;
			tbool = (ASN1_BOOLEAN *)pval;
			*tbool = *cont;
			}
		break;

		case V_ASN1_BIT_STRING:
		if (!c2i_ASN1_BIT_STRING((ASN1_BIT_STRING **)pval, &cont, len))
			goto err;
		break;

		case V_ASN1_INTEGER:
		case V_ASN1_NEG_INTEGER:
		case V_ASN1_ENUMERATED:
		case V_ASN1_NEG_ENUMERATED:
		tint = (ASN1_INTEGER **)pval;
		if (!c2i_ASN1_INTEGER(tint, &cont, len))
			goto err;
		/* Fixup type to match the expected form */
		(*tint)->type = utype | ((*tint)->type & V_ASN1_NEG);
		break;

		case V_ASN1_OCTET_STRING:
		case V_ASN1_NUMERICSTRING:
		case V_ASN1_PRINTABLESTRING:
		case V_ASN1_T61STRING:
		case V_ASN1_VIDEOTEXSTRING:
		case V_ASN1_IA5STRING:
		case V_ASN1_UTCTIME:
		case V_ASN1_GENERALIZEDTIME:
		case V_ASN1_GRAPHICSTRING:
		case V_ASN1_VISIBLESTRING:
		case V_ASN1_GENERALSTRING:
		case V_ASN1_UNIVERSALSTRING:
		case V_ASN1_BMPSTRING:
		case V_ASN1_UTF8STRING:
		case V_ASN1_OTHER:
		case V_ASN1_SET:
		case V_ASN1_SEQUENCE:
		default:
		/* All based on ASN1_STRING and handled the same */
		if (!*pval)
			{
			stmp = ASN1_STRING_type_new(utype);
			if (!stmp)
				{
				ASN1err(ASN1_F_ASN1_EX_C2I,
							ERR_R_MALLOC_FAILURE);
				goto err;
				}
			*pval = (ASN1_VALUE *)stmp;
			}
		else
			{
			stmp = (ASN1_STRING *)*pval;
			stmp->type = utype;
			}
		/* If we've already allocated a buffer use it */
		if (*free_cont)
			{
			if (stmp->data)
				OPENSSL_free(stmp->data);
			stmp->data = (unsigned char *)cont; /* UGLY CAST! RL */
			stmp->length = len;
			*free_cont = 0;
			}
		else
			{
			if (!ASN1_STRING_set(stmp, cont, len))
				{
				ASN1err(ASN1_F_ASN1_EX_C2I,
							ERR_R_MALLOC_FAILURE);
				ASN1_STRING_free(stmp);	
				*pval = NULL;
				goto err;
				}
			}
		break;
		}
	/* If ASN1_ANY and NULL type fix up value */
	if (typ && (utype == V_ASN1_NULL))
		 typ->value.ptr = NULL;

	ret = 1;
	err:
	if (!ret)
		{
		ASN1_TYPE_free(typ);
		if (opval)
			*opval = NULL;
		}
	return ret;
	}


/* This function finds the end of an ASN1 structure when passed its maximum
 * length, whether it is indefinite length and a pointer to the content.
 * This is more efficient than calling asn1_collect because it does not
 * recurse on each indefinite length header.
 */

static int asn1_find_end(const unsigned char **in, long len, char inf)
	{
	int expected_eoc;
	long plen;
	const unsigned char *p = *in, *q;
	/* If not indefinite length constructed just add length */
	if (inf == 0)
		{
		*in += len;
		return 1;
		}
	expected_eoc = 1;
	/* Indefinite length constructed form. Find the end when enough EOCs
	 * are found. If more indefinite length constructed headers
	 * are encountered increment the expected eoc count otherwise just
	 * skip to the end of the data.
	 */
	while (len > 0)
		{
		if(asn1_check_eoc(&p, len))
			{
			expected_eoc--;
			if (expected_eoc == 0)
				break;
			len -= 2;
			continue;
			}
		q = p;
		/* Just read in a header: only care about the length */
		if(!asn1_check_tlen(&plen, NULL, NULL, &inf, NULL, &p, len,
				-1, 0, 0, NULL))
			{
			ASN1err(ASN1_F_ASN1_FIND_END, ERR_R_NESTED_ASN1_ERROR);
			return 0;
			}
		if (inf)
			expected_eoc++;
		else
			p += plen;
		len -= p - q;
		}
	if (expected_eoc)
		{
		ASN1err(ASN1_F_ASN1_FIND_END, ASN1_R_MISSING_EOC);
		return 0;
		}
	*in = p;
	return 1;
	}
/* This function collects the asn1 data from a constructred string
 * type into a buffer. The values of 'in' and 'len' should refer
 * to the contents of the constructed type and 'inf' should be set
 * if it is indefinite length.
 */

static int asn1_collect(BUF_MEM *buf, const unsigned char **in, long len,
				char inf, int tag, int aclass)
	{
	const unsigned char *p, *q;
	long plen;
	char cst, ininf;
	p = *in;
	inf &= 1;
	/* If no buffer and not indefinite length constructed just pass over
	 * the encoded data */
	if (!buf && !inf)
		{
		*in += len;
		return 1;
		}
	while(len > 0)
		{
		q = p;
		/* Check for EOC */
		if (asn1_check_eoc(&p, len))
			{
			/* EOC is illegal outside indefinite length
			 * constructed form */
			if (!inf)
				{
				ASN1err(ASN1_F_ASN1_COLLECT,
					ASN1_R_UNEXPECTED_EOC);
				return 0;
				}
			inf = 0;
			break;
			}

		if (!asn1_check_tlen(&plen, NULL, NULL, &ininf, &cst, &p,
					len, tag, aclass, 0, NULL))
			{
			ASN1err(ASN1_F_ASN1_COLLECT, ERR_R_NESTED_ASN1_ERROR);
			return 0;
			}

		/* If indefinite length constructed update max length */
		if (cst)
			{
#ifdef OPENSSL_ALLOW_NESTED_ASN1_STRINGS
			if (!asn1_collect(buf, &p, plen, ininf, tag, aclass))
				return 0;
#else
			ASN1err(ASN1_F_ASN1_COLLECT, ASN1_R_NESTED_ASN1_STRING);
			return 0;
#endif
			}
		else if (plen && !collect_data(buf, &p, plen))
			return 0;
		len -= p - q;
		}
	if (inf)
		{
		ASN1err(ASN1_F_ASN1_COLLECT, ASN1_R_MISSING_EOC);
		return 0;
		}
	*in = p;
	return 1;
	}

static int collect_data(BUF_MEM *buf, const unsigned char **p, long plen)
	{
	int len;
	if (buf)
		{
		len = buf->length;
		if (!BUF_MEM_grow_clean(buf, len + plen))
			{
			ASN1err(ASN1_F_COLLECT_DATA, ERR_R_MALLOC_FAILURE);
			return 0;
			}
		memcpy(buf->data + len, *p, plen);
		}
	*p += plen;
	return 1;
	}

/* Check for ASN1 EOC and swallow it if found */

static int asn1_check_eoc(const unsigned char **in, long len)
	{
	const unsigned char *p;
	if (len < 2) return 0;
	p = *in;
	if (!p[0] && !p[1])
		{
		*in += 2;
		return 1;
		}
	return 0;
	}

/* Check an ASN1 tag and length: a bit like ASN1_get_object
 * but it sets the length for indefinite length constructed
 * form, we don't know the exact length but we can set an
 * upper bound to the amount of data available minus the
 * header length just read.
 */

static int asn1_check_tlen(long *olen, int *otag, unsigned char *oclass,
				char *inf, char *cst,
				const unsigned char **in, long len,
				int exptag, int expclass, char opt,
				ASN1_TLC *ctx)
	{
	int i;
	int ptag, pclass;
	long plen;
	const unsigned char *p, *q;
	p = *in;
	q = p;

	if (ctx && ctx->valid)
		{
		i = ctx->ret;
		plen = ctx->plen;
		pclass = ctx->pclass;
		ptag = ctx->ptag;
		p += ctx->hdrlen;
		}
	else
		{
		i = ASN1_get_object(&p, &plen, &ptag, &pclass, len);
		if (ctx)
			{
			ctx->ret = i;
			ctx->plen = plen;
			ctx->pclass = pclass;
			ctx->ptag = ptag;
			ctx->hdrlen = p - q;
			ctx->valid = 1;
			/* If definite length, and no error, length +
			 * header can't exceed total amount of data available. 
			 */
			if (!(i & 0x81) && ((plen + ctx->hdrlen) > len))
				{
				ASN1err(ASN1_F_ASN1_CHECK_TLEN,
							ASN1_R_TOO_LONG);
				asn1_tlc_clear(ctx);
				return 0;
				}
			}
		}

	if (i & 0x80)
		{
		ASN1err(ASN1_F_ASN1_CHECK_TLEN, ASN1_R_BAD_OBJECT_HEADER);
		asn1_tlc_clear(ctx);
		return 0;
		}
	if (exptag >= 0)
		{
		if ((exptag != ptag) || (expclass != pclass))
			{
			/* If type is OPTIONAL, not an error:
			 * indicate missing type.
			 */
			if (opt) return -1;
			asn1_tlc_clear(ctx);
			ASN1err(ASN1_F_ASN1_CHECK_TLEN, ASN1_R_WRONG_TAG);
			return 0;
			}
		/* We have a tag and class match:
		 * assume we are going to do something with it */
		asn1_tlc_clear(ctx);
		}

	if (i & 1)
		plen = len - (p - q);

	if (inf)
		*inf = i & 1;

	if (cst)
		*cst = i & V_ASN1_CONSTRUCTED;

	if (olen)
		*olen = plen;

	if (oclass)
		*oclass = pclass;

	if (otag)
		*otag = ptag;

	*in = p;
	return 1;
	}