xref: /openbsd/lib/libcrypto/asn1/tasn_dec.c (revision 09467b48)

/* $OpenBSD: tasn_dec.c,v 1.37 2019/04/01 15:48:04 jsing Exp $ */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project 2000.
 */
/* ====================================================================
 * Copyright (c) 2000-2005 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */


#include <stddef.h>
#include <string.h>
#include <openssl/asn1.h>
#include <openssl/asn1t.h>
#include <openssl/objects.h>
#include <openssl/buffer.h>
#include <openssl/err.h>

/* Constructed types with a recursive definition (such as can be found in PKCS7)
 * could eventually exceed the stack given malicious input with excessive
 * recursion. Therefore we limit the stack depth.
 */
#define ASN1_MAX_CONSTRUCTED_NEST 30

static int asn1_check_eoc(const unsigned char **in, long len);
static int asn1_find_end(const unsigned char **in, long len, char inf);

static int asn1_collect(BUF_MEM *buf, const unsigned char **in, long len,
    char inf, int tag, int aclass, int depth);

static int collect_data(BUF_MEM *buf, const unsigned char **p, long plen);

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);

static int asn1_template_ex_d2i(ASN1_VALUE **pval, const unsigned char **in,
    long len, const ASN1_TEMPLATE *tt, char opt, ASN1_TLC *ctx, int depth);
static int asn1_template_noexp_d2i(ASN1_VALUE **val, const unsigned char **in,
    long len, const ASN1_TEMPLATE *tt, char opt, ASN1_TLC *ctx, int depth);
static int asn1_d2i_ex_primitive(ASN1_VALUE **pval, const unsigned char **in,
    long len, const ASN1_ITEM *it, int tag, int aclass, char opt,
    ASN1_TLC *ctx);

/* Table to convert tags to bit values, used for MSTRING type */
static const unsigned long tag2bit[32] = {
	0,	0,	0,	B_ASN1_BIT_STRING,	/* tags  0 -  3 */
	B_ASN1_OCTET_STRING,	0,	0,		B_ASN1_UNKNOWN,/* tags  4- 7 */
	B_ASN1_UNKNOWN,	B_ASN1_UNKNOWN,	B_ASN1_UNKNOWN,	B_ASN1_UNKNOWN,/* tags  8-11 */
	B_ASN1_UTF8STRING,B_ASN1_UNKNOWN,B_ASN1_UNKNOWN,B_ASN1_UNKNOWN,/* tags 12-15 */
	B_ASN1_SEQUENCE,0,B_ASN1_NUMERICSTRING,B_ASN1_PRINTABLESTRING, /* tags 16-19 */
	B_ASN1_T61STRING,B_ASN1_VIDEOTEXSTRING,B_ASN1_IA5STRING,       /* tags 20-22 */
	B_ASN1_UTCTIME, B_ASN1_GENERALIZEDTIME,			       /* tags 23-24 */
	B_ASN1_GRAPHICSTRING,B_ASN1_ISO64STRING,B_ASN1_GENERALSTRING,  /* tags 25-27 */
	B_ASN1_UNIVERSALSTRING,B_ASN1_UNKNOWN,B_ASN1_BMPSTRING,B_ASN1_UNKNOWN, /* tags 28-31 */
};

unsigned long
ASN1_tag2bit(int tag)
{
	if ((tag < 0) || (tag > 30))
		return 0;
	return tag2bit[tag];
}

/* Macro to initialize and invalidate the cache */

#define asn1_tlc_clear(c)	if (c) (c)->valid = 0
/* Version to avoid compiler warning about 'c' always non-NULL */
#define asn1_tlc_clear_nc(c)	(c)->valid = 0

/* Decode an ASN1 item, this currently behaves just
 * like a standard 'd2i' function. 'in' points to
 * a buffer to read the data from, in future we will
 * have more advanced versions that can input data
 * a piece at a time and this will simply be a special
 * case.
 */

ASN1_VALUE *
ASN1_item_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
    const ASN1_ITEM *it)
{
	ASN1_TLC c;
	ASN1_VALUE *ptmpval = NULL;

	if (!pval)
		pval = &ptmpval;
	asn1_tlc_clear_nc(&c);
	if (ASN1_item_ex_d2i(pval, in, len, it, -1, 0, 0, &c) > 0)
		return *pval;
	return NULL;
}

int
ASN1_template_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
    const ASN1_TEMPLATE *tt)
{
	ASN1_TLC c;

	asn1_tlc_clear_nc(&c);
	return asn1_template_ex_d2i(pval, in, len, tt, 0, &c, 0);
}


/* Decode an item, taking care of IMPLICIT tagging, if any.
 * If 'opt' set and tag mismatch return -1 to handle OPTIONAL
 */

static int
asn1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
    const ASN1_ITEM *it, int tag, int aclass, char opt, ASN1_TLC *ctx,
    int depth)
{
	const ASN1_TEMPLATE *tt, *errtt = NULL;
	const ASN1_EXTERN_FUNCS *ef;
	const ASN1_AUX *aux = it->funcs;
	ASN1_aux_cb *asn1_cb = NULL;
	const unsigned char *p = NULL, *q;
	unsigned char oclass;
	char seq_eoc, seq_nolen, cst, isopt;
	long tmplen;
	int i;
	int otag;
	int ret = 0;
	ASN1_VALUE **pchptr;
	int combine;

	combine = aclass & ASN1_TFLG_COMBINE;
	aclass &= ~ASN1_TFLG_COMBINE;

	if (!pval)
		return 0;

	if (aux && aux->asn1_cb)
		asn1_cb = aux->asn1_cb;

	if (++depth > ASN1_MAX_CONSTRUCTED_NEST) {
		ASN1error(ASN1_R_NESTED_TOO_DEEP);
		goto err;
	}

	switch (it->itype) {
	case ASN1_ITYPE_PRIMITIVE:
		if (it->templates) {
			/* tagging or OPTIONAL is currently illegal on an item
			 * template because the flags can't get passed down.
			 * In practice this isn't a problem: we include the
			 * relevant flags from the item template in the
			 * template itself.
			 */
			if ((tag != -1) || opt) {
				ASN1error(ASN1_R_ILLEGAL_OPTIONS_ON_ITEM_TEMPLATE);
				goto err;
			}
			return asn1_template_ex_d2i(pval, in, len,
			    it->templates, opt, ctx, depth);
		}
		return asn1_d2i_ex_primitive(pval, in, len, it,
		    tag, aclass, opt, ctx);
		break;

	case ASN1_ITYPE_MSTRING:
		p = *in;
		/* Just read in tag and class */
		ret = asn1_check_tlen(NULL, &otag, &oclass, NULL, NULL,
		    &p, len, -1, 0, 1, ctx);
		if (!ret) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			goto err;
		}

		/* Must be UNIVERSAL class */
		if (oclass != V_ASN1_UNIVERSAL) {
			/* If OPTIONAL, assume this is OK */
			if (opt)
				return -1;
			ASN1error(ASN1_R_MSTRING_NOT_UNIVERSAL);
			goto err;
		}
		/* Check tag matches bit map */
		if (!(ASN1_tag2bit(otag) & it->utype)) {
			/* If OPTIONAL, assume this is OK */
			if (opt)
				return -1;
			ASN1error(ASN1_R_MSTRING_WRONG_TAG);
			goto err;
		}
		return asn1_d2i_ex_primitive(pval, in, len,
		    it, otag, 0, 0, ctx);

	case ASN1_ITYPE_EXTERN:
		/* Use new style d2i */
		ef = it->funcs;
		return ef->asn1_ex_d2i(pval, in, len,
		    it, tag, aclass, opt, ctx);

	case ASN1_ITYPE_CHOICE:
		if (asn1_cb && !asn1_cb(ASN1_OP_D2I_PRE, pval, it, NULL))
			goto auxerr;

		if (*pval) {
			/* Free up and zero CHOICE value if initialised */
			i = asn1_get_choice_selector(pval, it);
			if ((i >= 0) && (i < it->tcount)) {
				tt = it->templates + i;
				pchptr = asn1_get_field_ptr(pval, tt);
				ASN1_template_free(pchptr, tt);
				asn1_set_choice_selector(pval, -1, it);
			}
		} else if (!ASN1_item_ex_new(pval, it)) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			goto err;
		}
		/* CHOICE type, try each possibility in turn */
		p = *in;
		for (i = 0, tt = it->templates; i < it->tcount; i++, tt++) {
			pchptr = asn1_get_field_ptr(pval, tt);
			/* We mark field as OPTIONAL so its absence
			 * can be recognised.
			 */
			ret = asn1_template_ex_d2i(pchptr, &p, len, tt, 1, ctx,
				depth);
			/* If field not present, try the next one */
			if (ret == -1)
				continue;
			/* If positive return, read OK, break loop */
			if (ret > 0)
				break;
			/* Otherwise must be an ASN1 parsing error */
			errtt = tt;
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			goto err;
		}

		/* Did we fall off the end without reading anything? */
		if (i == it->tcount) {
			/* If OPTIONAL, this is OK */
			if (opt) {
				/* Free and zero it */
				ASN1_item_ex_free(pval, it);
				return -1;
			}
			ASN1error(ASN1_R_NO_MATCHING_CHOICE_TYPE);
			goto err;
		}

		asn1_set_choice_selector(pval, i, it);
		*in = p;
		if (asn1_cb && !asn1_cb(ASN1_OP_D2I_POST, pval, it, NULL))
			goto auxerr;
		return 1;

	case ASN1_ITYPE_NDEF_SEQUENCE:
	case ASN1_ITYPE_SEQUENCE:
		p = *in;
		tmplen = len;

		/* If no IMPLICIT tagging set to SEQUENCE, UNIVERSAL */
		if (tag == -1) {
			tag = V_ASN1_SEQUENCE;
			aclass = V_ASN1_UNIVERSAL;
		}
		/* Get SEQUENCE length and update len, p */
		ret = asn1_check_tlen(&len, NULL, NULL, &seq_eoc, &cst,
		    &p, len, tag, aclass, opt, ctx);
		if (!ret) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			goto err;
		} else if (ret == -1)
			return -1;
		if (aux && (aux->flags & ASN1_AFLG_BROKEN)) {
			len = tmplen - (p - *in);
			seq_nolen = 1;
		}
		/* If indefinite we don't do a length check */
		else
			seq_nolen = seq_eoc;
		if (!cst) {
			ASN1error(ASN1_R_SEQUENCE_NOT_CONSTRUCTED);
			goto err;
		}

		if (!*pval && !ASN1_item_ex_new(pval, it)) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			goto err;
		}

		if (asn1_cb && !asn1_cb(ASN1_OP_D2I_PRE, pval, it, NULL))
			goto auxerr;

		/* Free up and zero any ADB found */
		for (i = 0, tt = it->templates; i < it->tcount; i++, tt++) {
			if (tt->flags & ASN1_TFLG_ADB_MASK) {
				const ASN1_TEMPLATE *seqtt;
				ASN1_VALUE **pseqval;
				seqtt = asn1_do_adb(pval, tt, 1);
				if (!seqtt)
					goto err;
				pseqval = asn1_get_field_ptr(pval, seqtt);
				ASN1_template_free(pseqval, seqtt);
			}
		}

		/* Get each field entry */
		for (i = 0, tt = it->templates; i < it->tcount; i++, tt++) {
			const ASN1_TEMPLATE *seqtt;
			ASN1_VALUE **pseqval;
			seqtt = asn1_do_adb(pval, tt, 1);
			if (!seqtt)
				goto err;
			pseqval = asn1_get_field_ptr(pval, seqtt);
			/* Have we ran out of data? */
			if (!len)
				break;
			q = p;
			if (asn1_check_eoc(&p, len)) {
				if (!seq_eoc) {
					ASN1error(ASN1_R_UNEXPECTED_EOC);
					goto err;
				}
				len -= p - q;
				seq_eoc = 0;
				q = p;
				break;
			}
			/* This determines the OPTIONAL flag value. The field
			 * cannot be omitted if it is the last of a SEQUENCE
			 * and there is still data to be read. This isn't
			 * strictly necessary but it increases efficiency in
			 * some cases.
			 */
			if (i == (it->tcount - 1))
				isopt = 0;
			else
				isopt = (char)(seqtt->flags & ASN1_TFLG_OPTIONAL);
			/* attempt to read in field, allowing each to be
			 * OPTIONAL */

			ret = asn1_template_ex_d2i(pseqval, &p, len,
			    seqtt, isopt, ctx, depth);
			if (!ret) {
				errtt = seqtt;
				goto err;
			} else if (ret == -1) {
				/* OPTIONAL component absent.
				 * Free and zero the field.
				 */
				ASN1_template_free(pseqval, seqtt);
				continue;
			}
			/* Update length */
			len -= p - q;
		}

		/* Check for EOC if expecting one */
		if (seq_eoc && !asn1_check_eoc(&p, len)) {
			ASN1error(ASN1_R_MISSING_EOC);
			goto err;
		}
		/* Check all data read */
		if (!seq_nolen && len) {
			ASN1error(ASN1_R_SEQUENCE_LENGTH_MISMATCH);
			goto err;
		}

		/* If we get here we've got no more data in the SEQUENCE,
		 * however we may not have read all fields so check all
		 * remaining are OPTIONAL and clear any that are.
		 */
		for (; i < it->tcount; tt++, i++) {
			const ASN1_TEMPLATE *seqtt;
			seqtt = asn1_do_adb(pval, tt, 1);
			if (!seqtt)
				goto err;
			if (seqtt->flags & ASN1_TFLG_OPTIONAL) {
				ASN1_VALUE **pseqval;
				pseqval = asn1_get_field_ptr(pval, seqtt);
				ASN1_template_free(pseqval, seqtt);
			} else {
				errtt = seqtt;
				ASN1error(ASN1_R_FIELD_MISSING);
				goto err;
			}
		}
		/* Save encoding */
		if (!asn1_enc_save(pval, *in, p - *in, it)) {
			ASN1error(ERR_R_MALLOC_FAILURE);
			goto auxerr;
		}
		*in = p;
		if (asn1_cb && !asn1_cb(ASN1_OP_D2I_POST, pval, it, NULL))
			goto auxerr;
		return 1;

	default:
		return 0;
	}

auxerr:
	ASN1error(ASN1_R_AUX_ERROR);
err:
	if (combine == 0)
		ASN1_item_ex_free(pval, it);
	if (errtt)
		ERR_asprintf_error_data("Field=%s, Type=%s", errtt->field_name,
		    it->sname);
	else
		ERR_asprintf_error_data("Type=%s", it->sname);
	return 0;
}

int
ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
    const ASN1_ITEM *it, int tag, int aclass, char opt, ASN1_TLC *ctx)
{
	return asn1_item_ex_d2i(pval, in, len, it, tag, aclass, opt, ctx, 0);
}

/* Templates are handled with two separate functions.
 * One handles any EXPLICIT tag and the other handles the rest.
 */

static int
asn1_template_ex_d2i(ASN1_VALUE **val, const unsigned char **in, long inlen,
    const ASN1_TEMPLATE *tt, char opt, ASN1_TLC *ctx, int depth)
{
	int flags, aclass;
	int ret;
	long len;
	const unsigned char *p, *q;
	char exp_eoc;

	if (!val)
		return 0;
	flags = tt->flags;
	aclass = flags & ASN1_TFLG_TAG_CLASS;

	p = *in;

	/* Check if EXPLICIT tag expected */
	if (flags & ASN1_TFLG_EXPTAG) {
		char cst;
		/* Need to work out amount of data available to the inner
		 * content and where it starts: so read in EXPLICIT header to
		 * get the info.
		 */
		ret = asn1_check_tlen(&len, NULL, NULL, &exp_eoc, &cst,
		    &p, inlen, tt->tag, aclass, opt, ctx);
		q = p;
		if (!ret) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			return 0;
		} else if (ret == -1)
			return -1;
		if (!cst) {
			ASN1error(ASN1_R_EXPLICIT_TAG_NOT_CONSTRUCTED);
			return 0;
		}
		/* We've found the field so it can't be OPTIONAL now */
		ret = asn1_template_noexp_d2i(val, &p, len, tt, 0, ctx, depth);
		if (!ret) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			return 0;
		}
		/* We read the field in OK so update length */
		len -= p - q;
		if (exp_eoc) {
			/* If NDEF we must have an EOC here */
			if (!asn1_check_eoc(&p, len)) {
				ASN1error(ASN1_R_MISSING_EOC);
				goto err;
			}
		} else {
			/* Otherwise we must hit the EXPLICIT tag end or its
			 * an error */
			if (len) {
				ASN1error(ASN1_R_EXPLICIT_LENGTH_MISMATCH);
				goto err;
			}
		}
	} else
		return asn1_template_noexp_d2i(val, in, inlen, tt, opt, ctx,
			depth);

	*in = p;
	return 1;

err:
	ASN1_template_free(val, tt);
	return 0;
}

static int
asn1_template_noexp_d2i(ASN1_VALUE **val, const unsigned char **in, long len,
    const ASN1_TEMPLATE *tt, char opt, ASN1_TLC *ctx, int depth)
{
	int flags, aclass;
	int ret;
	const unsigned char *p, *q;

	if (!val)
		return 0;
	flags = tt->flags;
	aclass = flags & ASN1_TFLG_TAG_CLASS;

	p = *in;
	q = p;

	if (flags & ASN1_TFLG_SK_MASK) {
		/* SET OF, SEQUENCE OF */
		int sktag, skaclass;
		char sk_eoc;
		/* First work out expected inner tag value */
		if (flags & ASN1_TFLG_IMPTAG) {
			sktag = tt->tag;
			skaclass = aclass;
		} else {
			skaclass = V_ASN1_UNIVERSAL;
			if (flags & ASN1_TFLG_SET_OF)
				sktag = V_ASN1_SET;
			else
				sktag = V_ASN1_SEQUENCE;
		}
		/* Get the tag */
		ret = asn1_check_tlen(&len, NULL, NULL, &sk_eoc, NULL,
		    &p, len, sktag, skaclass, opt, ctx);
		if (!ret) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			return 0;
		} else if (ret == -1)
			return -1;
		if (!*val)
			*val = (ASN1_VALUE *)sk_new_null();
		else {
			/* We've got a valid STACK: free up any items present */
			STACK_OF(ASN1_VALUE) *sktmp =
			    (STACK_OF(ASN1_VALUE) *)*val;
			ASN1_VALUE *vtmp;
			while (sk_ASN1_VALUE_num(sktmp) > 0) {
				vtmp = sk_ASN1_VALUE_pop(sktmp);
				ASN1_item_ex_free(&vtmp,
				    tt->item);
			}
		}

		if (!*val) {
			ASN1error(ERR_R_MALLOC_FAILURE);
			goto err;
		}

		/* Read as many items as we can */
		while (len > 0) {
			ASN1_VALUE *skfield;
			q = p;
			/* See if EOC found */
			if (asn1_check_eoc(&p, len)) {
				if (!sk_eoc) {
					ASN1error(ASN1_R_UNEXPECTED_EOC);
					goto err;
				}
				len -= p - q;
				sk_eoc = 0;
				break;
			}
			skfield = NULL;
			if (!asn1_item_ex_d2i(&skfield, &p, len,
			    tt->item, -1, 0, 0, ctx, depth)) {
				ASN1error(ERR_R_NESTED_ASN1_ERROR);
				goto err;
			}
			len -= p - q;
			if (!sk_ASN1_VALUE_push((STACK_OF(ASN1_VALUE) *)*val,
			    skfield)) {
				ASN1error(ERR_R_MALLOC_FAILURE);
				goto err;
			}
		}
		if (sk_eoc) {
			ASN1error(ASN1_R_MISSING_EOC);
			goto err;
		}
	} else if (flags & ASN1_TFLG_IMPTAG) {
		/* IMPLICIT tagging */
		ret = asn1_item_ex_d2i(val, &p, len,
		    tt->item, tt->tag, aclass, opt, ctx, depth);
		if (!ret) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			goto err;
		} else if (ret == -1)
			return -1;
	} else {
		/* Nothing special */
		ret = asn1_item_ex_d2i(val, &p, len, tt->item,
		    -1, tt->flags & ASN1_TFLG_COMBINE, opt, ctx, depth);
		if (!ret) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			goto err;
		} else if (ret == -1)
			return -1;
	}

	*in = p;
	return 1;

err:
	ASN1_template_free(val, tt);
	return 0;
}

static int
asn1_d2i_ex_primitive(ASN1_VALUE **pval, const unsigned char **in, long inlen,
    const ASN1_ITEM *it, int tag, int aclass, char opt, ASN1_TLC *ctx)
{
	int ret = 0, utype;
	long plen;
	char cst, inf, free_cont = 0;
	const unsigned char *p;
	BUF_MEM buf;
	const unsigned char *cont = NULL;
	long len;

	buf.length = 0;
	buf.max = 0;
	buf.data = NULL;

	if (!pval) {
		ASN1error(ASN1_R_ILLEGAL_NULL);
		return 0; /* Should never happen */
	}

	if (it->itype == ASN1_ITYPE_MSTRING) {
		utype = tag;
		tag = -1;
	} else
		utype = it->utype;

	if (utype == V_ASN1_ANY) {
		/* If type is ANY need to figure out type from tag */
		unsigned char oclass;
		if (tag >= 0) {
			ASN1error(ASN1_R_ILLEGAL_TAGGED_ANY);
			return 0;
		}
		if (opt) {
			ASN1error(ASN1_R_ILLEGAL_OPTIONAL_ANY);
			return 0;
		}
		p = *in;
		ret = asn1_check_tlen(NULL, &utype, &oclass, NULL, NULL,
		    &p, inlen, -1, 0, 0, ctx);
		if (!ret) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			return 0;
		}
		if (oclass != V_ASN1_UNIVERSAL)
			utype = V_ASN1_OTHER;
	}
	if (tag == -1) {
		tag = utype;
		aclass = V_ASN1_UNIVERSAL;
	}
	p = *in;
	/* Check header */
	ret = asn1_check_tlen(&plen, NULL, NULL, &inf, &cst,
	    &p, inlen, tag, aclass, opt, ctx);
	if (!ret) {
		ASN1error(ERR_R_NESTED_ASN1_ERROR);
		return 0;
	} else if (ret == -1)
		return -1;
	ret = 0;
	/* SEQUENCE, SET and "OTHER" are left in encoded form */
	if ((utype == V_ASN1_SEQUENCE) || (utype == V_ASN1_SET) ||
	    (utype == V_ASN1_OTHER)) {
		/* Clear context cache for type OTHER because the auto clear
		 * when we have a exact match wont work
		 */
		if (utype == V_ASN1_OTHER) {
			asn1_tlc_clear(ctx);
		}
		/* SEQUENCE and SET must be constructed */
		else if (!cst) {
			ASN1error(ASN1_R_TYPE_NOT_CONSTRUCTED);
			return 0;
		}

		cont = *in;
		/* If indefinite length constructed find the real end */
		if (inf) {
			if (!asn1_find_end(&p, plen, inf))
				goto err;
			len = p - cont;
		} else {
			len = p - cont + plen;
			p += plen;
			buf.data = NULL;
		}
	} else if (cst) {
		/* Should really check the internal tags are correct but
		 * some things may get this wrong. The relevant specs
		 * say that constructed string types should be OCTET STRINGs
		 * internally irrespective of the type. So instead just check
		 * for UNIVERSAL class and ignore the tag.
		 */
		if (!asn1_collect(&buf, &p, plen, inf, -1, V_ASN1_UNIVERSAL, 0)) {
			free_cont = 1;
			goto err;
		}
		len = buf.length;
		/* Append a final null to string */
		if (!BUF_MEM_grow_clean(&buf, len + 1)) {
			ASN1error(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)
		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;
	ASN1_INTEGER **tint;
	int ret = 0;

	if (it->funcs != NULL) {
		const ASN1_PRIMITIVE_FUNCS *pf = it->funcs;

		if (pf->prim_c2i == NULL)
			return 0;
		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 = &typ->value.asn1_value;
	}
	switch (utype) {
	case V_ASN1_OBJECT:
		if (!c2i_ASN1_OBJECT((ASN1_OBJECT **)pval, &cont, len))
			goto err;
		break;

	case V_ASN1_NULL:
		if (len) {
			ASN1error(ASN1_R_NULL_IS_WRONG_LENGTH);
			goto err;
		}
		*pval = (ASN1_VALUE *)1;
		break;

	case V_ASN1_BOOLEAN:
		if (len != 1) {
			ASN1error(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_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:
		if (utype == V_ASN1_BMPSTRING && (len & 1)) {
			ASN1error(ASN1_R_BMPSTRING_IS_WRONG_LENGTH);
			goto err;
		}
		if (utype == V_ASN1_UNIVERSALSTRING && (len & 3)) {
			ASN1error(ASN1_R_UNIVERSALSTRING_IS_WRONG_LENGTH);
			goto err;
		}
		/* All based on ASN1_STRING and handled the same */
		if (!*pval) {
			stmp = ASN1_STRING_type_new(utype);
			if (!stmp) {
				ASN1error(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) {
			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)) {
				ASN1error(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)) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			return 0;
		}
		if (inf)
			expected_eoc++;
		else
			p += plen;
		len -= p - q;
	}
	if (expected_eoc) {
		ASN1error(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.
 */

#ifndef ASN1_MAX_STRING_NEST
/* This determines how many levels of recursion are permitted in ASN1
 * string types. If it is not limited stack overflows can occur. If set
 * to zero no recursion is allowed at all. Although zero should be adequate
 * examples exist that require a value of 1. So 5 should be more than enough.
 */
#define ASN1_MAX_STRING_NEST 5
#endif

static int
asn1_collect(BUF_MEM *buf, const unsigned char **in, long len, char inf,
    int tag, int aclass, int depth)
{
	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) {
				ASN1error(ASN1_R_UNEXPECTED_EOC);
				return 0;
			}
			inf = 0;
			break;
		}

		if (!asn1_check_tlen(&plen, NULL, NULL, &ininf, &cst, &p,
		    len, tag, aclass, 0, NULL)) {
			ASN1error(ERR_R_NESTED_ASN1_ERROR);
			return 0;
		}

		/* If indefinite length constructed update max length */
		if (cst) {
			if (depth >= ASN1_MAX_STRING_NEST) {
				ASN1error(ASN1_R_NESTED_ASN1_STRING);
				return 0;
			}
			if (!asn1_collect(buf, &p, plen, ininf, tag, aclass,
			    depth + 1))
				return 0;
		} else if (plen && !collect_data(buf, &p, plen))
			return 0;
		len -= p - q;
	}
	if (inf) {
		ASN1error(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)) {
			ASN1error(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)) {
				ASN1error(ASN1_R_TOO_LONG);
				asn1_tlc_clear(ctx);
				return 0;
			}
		}
	}

	if (i & 0x80) {
		ASN1error(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);
			ASN1error(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;
}