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secasn1d.c

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the Netscape security libraries.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1994-2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * Support for DEcoding ASN.1 data based on BER/DER (Basic/Distinguished
 * Encoding Rules).
 *
 * $Id: secasn1d.c,v 1.38 2007/10/12 01:44:51 julien.pierre.boogz%sun.com Exp $
 */

/* #define DEBUG_ASN1D_STATES 1 */

#ifdef DEBUG_ASN1D_STATES
#include <stdio.h>
#define PR_Assert sec_asn1d_Assert
#endif

#include "secasn1.h"
#include "secerr.h"

typedef enum {
    beforeIdentifier,
    duringIdentifier,
    afterIdentifier,
    beforeLength,
    duringLength,
    afterLength,
    beforeBitString,
    duringBitString,
    duringConstructedString,
    duringGroup,
    duringLeaf,
    duringSaveEncoding,
    duringSequence,
    afterConstructedString,
    afterGroup,
    afterExplicit,
    afterImplicit,
    afterInline,
    afterPointer,
    afterSaveEncoding,
    beforeEndOfContents,
    duringEndOfContents,
    afterEndOfContents,
    beforeChoice,
    duringChoice,
    afterChoice,
    notInUse
} sec_asn1d_parse_place;

#ifdef DEBUG_ASN1D_STATES
static const char * const place_names[] = {
    "beforeIdentifier",
    "duringIdentifier",
    "afterIdentifier",
    "beforeLength",
    "duringLength",
    "afterLength",
    "beforeBitString",
    "duringBitString",
    "duringConstructedString",
    "duringGroup",
    "duringLeaf",
    "duringSaveEncoding",
    "duringSequence",
    "afterConstructedString",
    "afterGroup",
    "afterExplicit",
    "afterImplicit",
    "afterInline",
    "afterPointer",
    "afterSaveEncoding",
    "beforeEndOfContents",
    "duringEndOfContents",
    "afterEndOfContents",
    "beforeChoice",
    "duringChoice",
    "afterChoice",
    "notInUse"
};

static const char * const class_names[] = {
    "UNIVERSAL",
    "APPLICATION",
    "CONTEXT_SPECIFIC",
    "PRIVATE"
};

static const char * const method_names[] = { "PRIMITIVE", "CONSTRUCTED" };

static const char * const type_names[] = {
    "END_OF_CONTENTS",
    "BOOLEAN",
    "INTEGER",
    "BIT_STRING",
    "OCTET_STRING",
    "NULL",
    "OBJECT_ID",
    "OBJECT_DESCRIPTOR",
    "(type 08)",
    "REAL",
    "ENUMERATED",
    "EMBEDDED",
    "UTF8_STRING",
    "(type 0d)",
    "(type 0e)",
    "(type 0f)",
    "SEQUENCE",
    "SET",
    "NUMERIC_STRING",
    "PRINTABLE_STRING",
    "T61_STRING",
    "VIDEOTEXT_STRING",
    "IA5_STRING",
    "UTC_TIME",
    "GENERALIZED_TIME",
    "GRAPHIC_STRING",
    "VISIBLE_STRING",
    "GENERAL_STRING",
    "UNIVERSAL_STRING",
    "(type 1d)",
    "BMP_STRING",
    "HIGH_TAG_VALUE"
};

static const char * const flag_names[] = { /* flags, right to left */
    "OPTIONAL",
    "EXPLICIT",
    "ANY",
    "INLINE",
    "POINTER",
    "GROUP",
    "DYNAMIC",
    "SKIP",
    "INNER",
    "SAVE",
    "",            /* decoder ignores "MAY_STREAM", */
    "SKIP_REST",
    "CHOICE",
    "NO_STREAM",
    "DEBUG_BREAK",
    "unknown 08",
    "unknown 10",
    "unknown 20",
    "unknown 40",
    "unknown 80"
};

static int /* bool */
formatKind(unsigned long kind, char * buf)
{
    int i;
    unsigned long k = kind & SEC_ASN1_TAGNUM_MASK;
    unsigned long notag = kind & (SEC_ASN1_CHOICE | SEC_ASN1_POINTER |
        SEC_ASN1_INLINE | SEC_ASN1_ANY | SEC_ASN1_SAVE);

    buf[0] = 0;
    if ((kind & SEC_ASN1_CLASS_MASK) != SEC_ASN1_UNIVERSAL) {
        sprintf(buf, " %s", class_names[(kind & SEC_ASN1_CLASS_MASK) >> 6] );
        buf += strlen(buf);
    }
    if (kind & SEC_ASN1_METHOD_MASK) {
        sprintf(buf, " %s", method_names[1]);
        buf += strlen(buf);
    }
    if ((kind & SEC_ASN1_CLASS_MASK) == SEC_ASN1_UNIVERSAL) {
        if (k || !notag) {
            sprintf(buf, " %s", type_names[k] );
            if ((k == SEC_ASN1_SET || k == SEC_ASN1_SEQUENCE) &&
                (kind & SEC_ASN1_GROUP)) {
                buf += strlen(buf);
                sprintf(buf, "_OF");
            }
        }
    } else {
        sprintf(buf, " [%d]", k);
    }
    buf += strlen(buf);

    for (k = kind >> 8, i = 0; k; k >>= 1, ++i) {
        if (k & 1) {
            sprintf(buf, " %s", flag_names[i]);
            buf += strlen(buf);
        }
    }
    return notag != 0;
}

#endif /* DEBUG_ASN1D_STATES */

typedef enum {
    allDone,
    decodeError,
    keepGoing,
    needBytes
} sec_asn1d_parse_status;

struct subitem {
    const void *data;
    unsigned long len;        /* only used for substrings */
    struct subitem *next;
};

typedef struct sec_asn1d_state_struct {
    SEC_ASN1DecoderContext *top;
    const SEC_ASN1Template *theTemplate;
    void *dest;

    void *our_mark;     /* free on completion */

    struct sec_asn1d_state_struct *parent;      /* aka prev */
    struct sec_asn1d_state_struct *child; /* aka next */

    sec_asn1d_parse_place place;

    /*
     * XXX explain the next fields as clearly as possible...
     */
    unsigned char found_tag_modifiers;
    unsigned char expect_tag_modifiers;
    unsigned long check_tag_mask;
    unsigned long found_tag_number;
    unsigned long expect_tag_number;
    unsigned long underlying_kind;

    unsigned long contents_length;
    unsigned long pending;
    unsigned long consumed;

    int depth;

    /*
     * Bit strings have their length adjusted -- the first octet of the
     * contents contains a value between 0 and 7 which says how many bits
     * at the end of the octets are not actually part of the bit string;
     * when parsing bit strings we put that value here because we need it
     * later, for adjustment of the length (when the whole string is done).
     */
    unsigned int bit_string_unused_bits;

    /*
     * The following are used for indefinite-length constructed strings.
     */
    struct subitem *subitems_head;
    struct subitem *subitems_tail;

    PRPackedBool
      allocate,   /* when true, need to allocate the destination */
      endofcontents,    /* this state ended up parsing end-of-contents octets */
      explicit,   /* we are handling an explicit header */
      indefinite, /* the current item has indefinite-length encoding */
      missing,    /* an optional field that was not present */
      optional,   /* the template says this field may be omitted */
      substring;  /* this is a substring of a constructed string */

} sec_asn1d_state;

#define IS_HIGH_TAG_NUMBER(n) ((n) == SEC_ASN1_HIGH_TAG_NUMBER)
#define LAST_TAG_NUMBER_BYTE(b)     (((b) & 0x80) == 0)
#define TAG_NUMBER_BITS       7
#define TAG_NUMBER_MASK       0x7f

#define LENGTH_IS_SHORT_FORM(b)     (((b) & 0x80) == 0)
#define LONG_FORM_LENGTH(b)   ((b) & 0x7f)

#define HIGH_BITS(field,cnt)  ((field) >> ((sizeof(field) * 8) - (cnt)))


/*
 * An "outsider" will have an opaque pointer to this, created by calling
 * SEC_ASN1DecoderStart().  It will be passed back in to all subsequent
 * calls to SEC_ASN1DecoderUpdate(), and when done it is passed to
 * SEC_ASN1DecoderFinish().
 */
struct sec_DecoderContext_struct {
    PRArenaPool *our_pool;          /* for our internal allocs */
    PRArenaPool *their_pool;        /* for destination structure allocs */
#ifdef SEC_ASN1D_FREE_ON_ERROR            /*
                               * XXX see comment below (by same
                               * ifdef) that explains why this
                               * does not work (need more smarts
                               * in order to free back to mark)
                               */
    /*
     * XXX how to make their_mark work in the case where they do NOT
     * give us a pool pointer?
     */
    void *their_mark;               /* free on error */
#endif

    sec_asn1d_state *current;
    sec_asn1d_parse_status status;

    SEC_ASN1NotifyProc notify_proc; /* call before/after handling field */
    void *notify_arg;               /* argument to notify_proc */
    PRBool during_notify;           /* true during call to notify_proc */

    SEC_ASN1WriteProc filter_proc;  /* pass field bytes to this  */
    void *filter_arg;               /* argument to that function */
    PRBool filter_only;             /* do not allocate/store fields */
};


/*
 * XXX this is a fairly generic function that may belong elsewhere
 */
static void *
sec_asn1d_alloc (PRArenaPool *poolp, unsigned long len)
{
    void *thing;

    if (poolp != NULL) {
      /*
       * Allocate from the pool.
       */
      thing = PORT_ArenaAlloc (poolp, len);
    } else {
      /*
       * Allocate generically.
       */
      thing = PORT_Alloc (len);
    }

    return thing;
}


/*
 * XXX this is a fairly generic function that may belong elsewhere
 */
static void *
sec_asn1d_zalloc (PRArenaPool *poolp, unsigned long len)
{
    void *thing;

    thing = sec_asn1d_alloc (poolp, len);
    if (thing != NULL)
      PORT_Memset (thing, 0, len);
    return thing;
}


static sec_asn1d_state *
sec_asn1d_push_state (SEC_ASN1DecoderContext *cx,
                  const SEC_ASN1Template *theTemplate,
                  void *dest, PRBool new_depth)
{
    sec_asn1d_state *state, *new_state;

    state = cx->current;

    PORT_Assert (state == NULL || state->child == NULL);

    if (state != NULL) {
      PORT_Assert (state->our_mark == NULL);
      state->our_mark = PORT_ArenaMark (cx->our_pool);
    }

    new_state = (sec_asn1d_state*)sec_asn1d_zalloc (cx->our_pool, 
                                        sizeof(*new_state));
    if (new_state == NULL) {
      goto loser;
    }

    new_state->top         = cx;
    new_state->parent      = state;
    new_state->theTemplate = theTemplate;
    new_state->place       = notInUse;
    if (dest != NULL)
      new_state->dest = (char *)dest + theTemplate->offset;

    if (state != NULL) {
      new_state->depth = state->depth;
      if (new_depth) {
          if (++new_state->depth > SEC_ASN1D_MAX_DEPTH) {
            PORT_SetError (SEC_ERROR_BAD_DER);
            goto loser;
          }
      }
      state->child = new_state;
    }

    cx->current = new_state;
    return new_state;

loser:
    cx->status = decodeError;
    if (state != NULL) {
      PORT_ArenaRelease(cx->our_pool, state->our_mark);
      state->our_mark = NULL;
    }
    return NULL;
}


static void
sec_asn1d_scrub_state (sec_asn1d_state *state)
{
    /*
     * Some default "scrubbing".
     * XXX right set of initializations?
     */
    state->place = beforeIdentifier;
    state->endofcontents = PR_FALSE;
    state->indefinite = PR_FALSE;
    state->missing = PR_FALSE;
    PORT_Assert (state->consumed == 0);
}


static void
sec_asn1d_notify_before (SEC_ASN1DecoderContext *cx, void *dest, int depth)
{
    if (cx->notify_proc == NULL)
      return;

    cx->during_notify = PR_TRUE;
    (* cx->notify_proc) (cx->notify_arg, PR_TRUE, dest, depth);
    cx->during_notify = PR_FALSE;
}


static void
sec_asn1d_notify_after (SEC_ASN1DecoderContext *cx, void *dest, int depth)
{
    if (cx->notify_proc == NULL)
      return;

    cx->during_notify = PR_TRUE;
    (* cx->notify_proc) (cx->notify_arg, PR_FALSE, dest, depth);
    cx->during_notify = PR_FALSE;
}


static sec_asn1d_state *
sec_asn1d_init_state_based_on_template (sec_asn1d_state *state)
{
    PRBool explicit, optional, universal;
    unsigned char expect_tag_modifiers;
    unsigned long encode_kind, under_kind;
    unsigned long check_tag_mask, expect_tag_number;


    /* XXX Check that both of these tests are really needed/appropriate. */
    if (state == NULL || state->top->status == decodeError)
      return state;

    encode_kind = state->theTemplate->kind;

    if (encode_kind & SEC_ASN1_SAVE) {
      /*
       * This is a "magic" field that saves away all bytes, allowing
       * the immediately following field to still be decoded from this
       * same spot -- sort of a fork.
       */
      /* check that there are no extraneous bits */
      PORT_Assert (encode_kind == SEC_ASN1_SAVE);
      if (state->top->filter_only) {
          /*
           * If we are not storing, then we do not do the SAVE field
           * at all.  Just move ahead to the "real" field instead,
           * doing the appropriate notify calls before and after.
           */
          sec_asn1d_notify_after (state->top, state->dest, state->depth);
          /*
           * Since we are not storing, allow for our current dest value
           * to be NULL.  (This might not actually occur, but right now I
           * cannot convince myself one way or the other.)  If it is NULL,
           * assume that our parent dest can help us out.
           */
          if (state->dest == NULL)
            state->dest = state->parent->dest;
          else
            state->dest = (char *)state->dest - state->theTemplate->offset;
          state->theTemplate++;
          if (state->dest != NULL)
            state->dest = (char *)state->dest + state->theTemplate->offset;
          sec_asn1d_notify_before (state->top, state->dest, state->depth);
          encode_kind = state->theTemplate->kind;
          PORT_Assert ((encode_kind & SEC_ASN1_SAVE) == 0);
      } else {
          sec_asn1d_scrub_state (state);
          state->place = duringSaveEncoding;
          state = sec_asn1d_push_state (state->top, SEC_AnyTemplate,
                                state->dest, PR_FALSE);
          if (state != NULL)
            state = sec_asn1d_init_state_based_on_template (state);
          return state;
      }
    }


    universal = ((encode_kind & SEC_ASN1_CLASS_MASK) == SEC_ASN1_UNIVERSAL)
            ? PR_TRUE : PR_FALSE;

    explicit = (encode_kind & SEC_ASN1_EXPLICIT) ? PR_TRUE : PR_FALSE;
    encode_kind &= ~SEC_ASN1_EXPLICIT;

    optional = (encode_kind & SEC_ASN1_OPTIONAL) ? PR_TRUE : PR_FALSE;
    encode_kind &= ~SEC_ASN1_OPTIONAL;

    PORT_Assert (!(explicit && universal));     /* bad templates */

    encode_kind &= ~SEC_ASN1_DYNAMIC;
    encode_kind &= ~SEC_ASN1_MAY_STREAM;

    if (encode_kind & SEC_ASN1_CHOICE) {
#if 0 /* XXX remove? */
      sec_asn1d_state *child = sec_asn1d_push_state(state->top, state->theTemplate, state->dest, PR_FALSE);
      if ((sec_asn1d_state *)NULL == child) {
        return (sec_asn1d_state *)NULL;
      }

      child->allocate = state->allocate;
      child->place = beforeChoice;
      return child;
#else
      state->place = beforeChoice;
      return state;
#endif
    }

    if ((encode_kind & (SEC_ASN1_POINTER | SEC_ASN1_INLINE)) || (!universal
                                                && !explicit)) {
      const SEC_ASN1Template *subt;
      void *dest;
      PRBool child_allocate;

      PORT_Assert ((encode_kind & (SEC_ASN1_ANY | SEC_ASN1_SKIP)) == 0);

      sec_asn1d_scrub_state (state);
      child_allocate = PR_FALSE;

      if (encode_kind & SEC_ASN1_POINTER) {
          /*
           * A POINTER means we need to allocate the destination for
           * this field.  But, since it may also be an optional field,
           * we defer the allocation until later; we just record that
           * it needs to be done.
           *
           * There are two possible scenarios here -- one is just a
           * plain POINTER (kind of like INLINE, except with allocation)
           * and the other is an implicitly-tagged POINTER.  We don't
           * need to do anything special here for the two cases, but
           * since the template definition can be tricky, we do check
           * that there are no extraneous bits set in encode_kind.
           *
           * XXX The same conditions which assert should set an error.
           */
          if (universal) {
            /*
             * "universal" means this entry is a standalone POINTER;
             * there should be no other bits set in encode_kind.
             */
            PORT_Assert (encode_kind == SEC_ASN1_POINTER);
          } else {
            /*
             * If we get here we have an implicitly-tagged field
             * that needs to be put into a POINTER.  The subtemplate
             * will determine how to decode the field, but encode_kind
             * describes the (implicit) tag we are looking for.
             * The non-tag bits of encode_kind will be ignored by
             * the code below; none of them should be set, however,
             * except for the POINTER bit itself -- so check that.
             */
            PORT_Assert ((encode_kind & ~SEC_ASN1_TAG_MASK)
                       == SEC_ASN1_POINTER);
          }
          if (!state->top->filter_only)
            child_allocate = PR_TRUE;
          dest = NULL;
          state->place = afterPointer;
      } else {
          dest = state->dest;
          if (encode_kind & SEC_ASN1_INLINE) {
            /* check that there are no extraneous bits */
            PORT_Assert (encode_kind == SEC_ASN1_INLINE && !optional);
            state->place = afterInline;
          } else {
            state->place = afterImplicit;
          }
      }

      state->optional = optional;
      subt = SEC_ASN1GetSubtemplate (state->theTemplate, state->dest, PR_FALSE);
      state = sec_asn1d_push_state (state->top, subt, dest, PR_FALSE);
      if (state == NULL)
          return NULL;

      state->allocate = child_allocate;

      if (universal) {
          state = sec_asn1d_init_state_based_on_template (state);
          if (state != NULL) {
            /*
             * If this field is optional, we need to record that on
             * the pushed child so it won't fail if the field isn't
             * found.  I can't think of a way that this new state
             * could already have optional set (which we would wipe
             * out below if our local optional is not set) -- but
             * just to be sure, assert that it isn't set.
             */
            PORT_Assert (!state->optional);
            state->optional = optional;
          }
          return state;
      }

      under_kind = state->theTemplate->kind;
      under_kind &= ~SEC_ASN1_MAY_STREAM;
    } else if (explicit) {
      /*
       * For explicit, we only need to match the encoding tag next,
       * then we will push another state to handle the entire inner
       * part.  In this case, there is no underlying kind which plays
       * any part in the determination of the outer, explicit tag.
       * So we just set under_kind to 0, which is not a valid tag,
       * and the rest of the tag matching stuff should be okay.
       */
      under_kind = 0;
    } else {
      /*
       * Nothing special; the underlying kind and the given encoding
       * information are the same.
       */
      under_kind = encode_kind;
    }

    /* XXX is this the right set of bits to test here? */
    PORT_Assert ((under_kind & (SEC_ASN1_EXPLICIT | SEC_ASN1_OPTIONAL
                        | SEC_ASN1_MAY_STREAM
                        | SEC_ASN1_INLINE | SEC_ASN1_POINTER)) == 0);

    if (encode_kind & (SEC_ASN1_ANY | SEC_ASN1_SKIP)) {
      PORT_Assert (encode_kind == under_kind);
      if (encode_kind & SEC_ASN1_SKIP) {
          PORT_Assert (!optional);
          PORT_Assert (encode_kind == SEC_ASN1_SKIP);
          state->dest = NULL;
      }
      check_tag_mask = 0;
      expect_tag_modifiers = 0;
      expect_tag_number = 0;
    } else {
      check_tag_mask = SEC_ASN1_TAG_MASK;
      expect_tag_modifiers = (unsigned char)encode_kind & SEC_ASN1_TAG_MASK
                        & ~SEC_ASN1_TAGNUM_MASK;
      /*
       * XXX This assumes only single-octet identifiers.  To handle
       * the HIGH TAG form we would need to do some more work, especially
       * in how to specify them in the template, because right now we
       * do not provide a way to specify more *tag* bits in encode_kind.
       */
      expect_tag_number = encode_kind & SEC_ASN1_TAGNUM_MASK;

      switch (under_kind & SEC_ASN1_TAGNUM_MASK) {
        case SEC_ASN1_SET:
          /*
           * XXX A plain old SET (as opposed to a SET OF) is not implemented.
           * If it ever is, remove this assert...
           */
          PORT_Assert ((under_kind & SEC_ASN1_GROUP) != 0);
          /* fallthru */
        case SEC_ASN1_SEQUENCE:
          expect_tag_modifiers |= SEC_ASN1_CONSTRUCTED;
          break;
        case SEC_ASN1_BIT_STRING:
        case SEC_ASN1_BMP_STRING:
        case SEC_ASN1_GENERALIZED_TIME:
        case SEC_ASN1_IA5_STRING:
        case SEC_ASN1_OCTET_STRING:
        case SEC_ASN1_PRINTABLE_STRING:
        case SEC_ASN1_T61_STRING:
        case SEC_ASN1_UNIVERSAL_STRING:
        case SEC_ASN1_UTC_TIME:
        case SEC_ASN1_UTF8_STRING:
        case SEC_ASN1_VISIBLE_STRING:
          check_tag_mask &= ~SEC_ASN1_CONSTRUCTED;
          break;
      }
    }

    state->check_tag_mask = check_tag_mask;
    state->expect_tag_modifiers = expect_tag_modifiers;
    state->expect_tag_number = expect_tag_number;
    state->underlying_kind = under_kind;
    state->explicit = explicit;
    state->optional = optional;

    sec_asn1d_scrub_state (state);

    return state;
}

static sec_asn1d_state *
sec_asn1d_get_enclosing_construct(sec_asn1d_state *state)
{
    for (state = state->parent; state; state = state->parent) {
      sec_asn1d_parse_place place = state->place;
      if (place != afterImplicit      &&
          place != afterPointer       &&
          place != afterInline        &&
          place != afterSaveEncoding  &&
          place != duringSaveEncoding &&
          place != duringChoice) {

            /* we've walked up the stack to a state that represents
            ** the enclosing construct.  
          */
            break;
      }
    }
    return state;
}

static PRBool
sec_asn1d_parent_allows_EOC(sec_asn1d_state *state)
{
    /* get state of enclosing construct. */
    state = sec_asn1d_get_enclosing_construct(state);
    if (state) {
      sec_asn1d_parse_place place = state->place;
        /* Is it one of the types that permits an unexpected EOC? */
      int eoc_permitted = 
          (place == duringGroup ||
           place == duringConstructedString ||
           state->child->optional);
      return (state->indefinite && eoc_permitted) ? PR_TRUE : PR_FALSE;
    }
    return PR_FALSE;
}

static unsigned long
sec_asn1d_parse_identifier (sec_asn1d_state *state,
                      const char *buf, unsigned long len)
{
    unsigned char byte;
    unsigned char tag_number;

    PORT_Assert (state->place == beforeIdentifier);

    if (len == 0) {
      state->top->status = needBytes;
      return 0;
    }

    byte = (unsigned char) *buf;
#ifdef DEBUG_ASN1D_STATES
    {
        char kindBuf[256];
        formatKind(byte, kindBuf);
        printf("Found tag %02x %s\n", byte, kindBuf);
    }
#endif
    tag_number = byte & SEC_ASN1_TAGNUM_MASK;

    if (IS_HIGH_TAG_NUMBER (tag_number)) {
      state->place = duringIdentifier;
      state->found_tag_number = 0;
      /*
       * Actually, we have no idea how many bytes are pending, but we
       * do know that it is at least 1.  That is all we know; we have
       * to look at each byte to know if there is another, etc.
       */
      state->pending = 1;
    } else {
      if (byte == 0 && sec_asn1d_parent_allows_EOC(state)) {
          /*
           * Our parent has indefinite-length encoding, and the
           * entire tag found is 0, so it seems that we have hit the
           * end-of-contents octets.  To handle this, we just change
           * our state to that which expects to get the bytes of the
           * end-of-contents octets and let that code re-read this byte
           * so that our categorization of field types is correct.
           * After that, our parent will then deal with everything else.
           */
          state->place = duringEndOfContents;
          state->pending = 2;
          state->found_tag_number = 0;
          state->found_tag_modifiers = 0;
          /*
           * We might be an optional field that is, as we now find out,
           * missing.  Give our parent a clue that this happened.
           */
          if (state->optional)
            state->missing = PR_TRUE;
          return 0;
      }
      state->place = afterIdentifier;
      state->found_tag_number = tag_number;
    }
    state->found_tag_modifiers = byte & ~SEC_ASN1_TAGNUM_MASK;

    return 1;
}


static unsigned long
sec_asn1d_parse_more_identifier (sec_asn1d_state *state,
                         const char *buf, unsigned long len)
{
    unsigned char byte;
    int count;

    PORT_Assert (state->pending == 1);
    PORT_Assert (state->place == duringIdentifier);

    if (len == 0) {
      state->top->status = needBytes;
      return 0;
    }

    count = 0;

    while (len && state->pending) {
      if (HIGH_BITS (state->found_tag_number, TAG_NUMBER_BITS) != 0) {
          /*
           * The given high tag number overflows our container;
           * just give up.  This is not likely to *ever* happen.
           */
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          return 0;
      }

      state->found_tag_number <<= TAG_NUMBER_BITS;

      byte = (unsigned char) buf[count++];
      state->found_tag_number |= (byte & TAG_NUMBER_MASK);

      len--;
      if (LAST_TAG_NUMBER_BYTE (byte))
          state->pending = 0;
    }

    if (state->pending == 0)
      state->place = afterIdentifier;

    return count;
}


static void
sec_asn1d_confirm_identifier (sec_asn1d_state *state)
{
    PRBool match;

    PORT_Assert (state->place == afterIdentifier);

    match = (PRBool)(((state->found_tag_modifiers & state->check_tag_mask)
           == state->expect_tag_modifiers)
          && ((state->found_tag_number & state->check_tag_mask)
            == state->expect_tag_number));
    if (match) {
      state->place = beforeLength;
    } else {
      if (state->optional) {
          state->missing = PR_TRUE;
          state->place = afterEndOfContents;
      } else {
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
      }
    }
}


static unsigned long
sec_asn1d_parse_length (sec_asn1d_state *state,
                  const char *buf, unsigned long len)
{
    unsigned char byte;

    PORT_Assert (state->place == beforeLength);

    if (len == 0) {
      state->top->status = needBytes;
      return 0;
    }

    /*
     * The default/likely outcome.  It may get adjusted below.
     */
    state->place = afterLength;

    byte = (unsigned char) *buf;

    if (LENGTH_IS_SHORT_FORM (byte)) {
      state->contents_length = byte;
    } else {
      state->contents_length = 0;
      state->pending = LONG_FORM_LENGTH (byte);
      if (state->pending == 0) {
          state->indefinite = PR_TRUE;
      } else {
          state->place = duringLength;
      }
    }

    /* If we're parsing an ANY, SKIP, or SAVE template, and 
    ** the object being saved is definite length encoded and constructed, 
    ** there's no point in decoding that construct's members.
    ** So, just forget it's constructed and treat it as primitive.
    ** (SAVE appears as an ANY at this point)
    */
    if (!state->indefinite &&
      (state->underlying_kind & (SEC_ASN1_ANY | SEC_ASN1_SKIP))) {
      state->found_tag_modifiers &= ~SEC_ASN1_CONSTRUCTED;
    }

    return 1;
}


static unsigned long
sec_asn1d_parse_more_length (sec_asn1d_state *state,
                       const char *buf, unsigned long len)
{
    int count;

    PORT_Assert (state->pending > 0);
    PORT_Assert (state->place == duringLength);

    if (len == 0) {
      state->top->status = needBytes;
      return 0;
    }

    count = 0;

    while (len && state->pending) {
      if (HIGH_BITS (state->contents_length, 9) != 0) {
          /*
           * The given full content length overflows our container;
           * just give up.
           */
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          return 0;
      }

      state->contents_length <<= 8;
      state->contents_length |= (unsigned char) buf[count++];

      len--;
      state->pending--;
    }

    if (state->pending == 0)
      state->place = afterLength;

    return count;
}


static void
sec_asn1d_prepare_for_contents (sec_asn1d_state *state)
{
    SECItem *item;
    PRArenaPool *poolp;
    unsigned long alloc_len;

#ifdef DEBUG_ASN1D_STATES
    {
        printf("Found Length %d %s\n", state->contents_length,
               state->indefinite ? "indefinite" : "");
    }
#endif

    /*
     * XXX I cannot decide if this allocation should exclude the case
     *     where state->endofcontents is true -- figure it out!
     */
    if (state->allocate) {
      void *dest;

      PORT_Assert (state->dest == NULL);
      /*
       * We are handling a POINTER or a member of a GROUP, and need to
       * allocate for the data structure.
       */
      dest = sec_asn1d_zalloc (state->top->their_pool,
                         state->theTemplate->size);
      if (dest == NULL) {
          state->top->status = decodeError;
          return;
      }
      state->dest = (char *)dest + state->theTemplate->offset;

      /*
       * For a member of a GROUP, our parent will later put the
       * pointer wherever it belongs.  But for a POINTER, we need
       * to record the destination now, in case notify or filter
       * procs need access to it -- they cannot find it otherwise,
       * until it is too late (for one-pass processing).
       */
      if (state->parent->place == afterPointer) {
          void **placep;

          placep = state->parent->dest;
          *placep = dest;
      }
    }

    /*
     * Remember, length may be indefinite here!  In that case,
     * both contents_length and pending will be zero.
     */
    state->pending = state->contents_length;

    /* If this item has definite length encoding, and 
    ** is enclosed by a definite length constructed type,
    ** make sure it isn't longer than the remaining space in that 
    ** constructed type.  
    */
    if (state->contents_length > 0) {
      sec_asn1d_state *parent = sec_asn1d_get_enclosing_construct(state);
      if (parent && !parent->indefinite && 
          state->consumed + state->contents_length > parent->pending) {
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          return;
      }
    }

    /*
     * An EXPLICIT is nothing but an outer header, which we have
     * already parsed and accepted.  Now we need to do the inner
     * header and its contents.
     */
    if (state->explicit) {
      state->place = afterExplicit;
      state = sec_asn1d_push_state (state->top,
                              SEC_ASN1GetSubtemplate(state->theTemplate,
                                               state->dest,
                                               PR_FALSE),
                              state->dest, PR_TRUE);
      if (state != NULL)
          state = sec_asn1d_init_state_based_on_template (state);
      return;
    }

    /*
     * For GROUP (SET OF, SEQUENCE OF), even if we know the length here
     * we cannot tell how many items we will end up with ... so push a
     * state that can keep track of "children" (the individual members
     * of the group; we will allocate as we go and put them all together
     * at the end.
     */
    if (state->underlying_kind & SEC_ASN1_GROUP) {
      /* XXX If this assertion holds (should be able to confirm it via
       * inspection, too) then move this code into the switch statement
       * below under cases SET_OF and SEQUENCE_OF; it will be cleaner.
       */
      PORT_Assert (state->underlying_kind == SEC_ASN1_SET_OF
         || state->underlying_kind == SEC_ASN1_SEQUENCE_OF
         || state->underlying_kind == (SEC_ASN1_SEQUENCE_OF|SEC_ASN1_DYNAMIC)
         || state->underlying_kind == (SEC_ASN1_SEQUENCE_OF|SEC_ASN1_DYNAMIC)
                 );
      if (state->contents_length != 0 || state->indefinite) {
          const SEC_ASN1Template *subt;

          state->place = duringGroup;
          subt = SEC_ASN1GetSubtemplate (state->theTemplate, state->dest,
                                 PR_FALSE);
          state = sec_asn1d_push_state (state->top, subt, NULL, PR_TRUE);
          if (state != NULL) {
            if (!state->top->filter_only)
                state->allocate = PR_TRUE;      /* XXX propogate this? */
            /*
             * Do the "before" field notification for next in group.
             */
            sec_asn1d_notify_before (state->top, state->dest, state->depth);
            state = sec_asn1d_init_state_based_on_template (state);
          }
      } else {
          /*
           * A group of zero; we are done.
           * Set state to afterGroup and let that code plant the NULL.
           */
          state->place = afterGroup;
      }
      return;
    }

    switch (state->underlying_kind) {
      case SEC_ASN1_SEQUENCE:
      /*
       * We need to push a child to handle the individual fields.
       */
      state->place = duringSequence;
      state = sec_asn1d_push_state (state->top, state->theTemplate + 1,
                              state->dest, PR_TRUE);
      if (state != NULL) {
          /*
           * Do the "before" field notification.
           */
          sec_asn1d_notify_before (state->top, state->dest, state->depth);
          state = sec_asn1d_init_state_based_on_template (state);
      }
      break;

      case SEC_ASN1_SET:      /* XXX SET is not really implemented */
      /*
       * XXX A plain SET requires special handling; scanning of a
       * template to see where a field should go (because by definition,
       * they are not in any particular order, and you have to look at
       * each tag to disambiguate what the field is).  We may never
       * implement this because in practice, it seems to be unused.
       */
      PORT_Assert(0);
      PORT_SetError (SEC_ERROR_BAD_DER); /* XXX */
      state->top->status = decodeError;
      break;

      case SEC_ASN1_NULL:
      /*
       * The NULL type, by definition, is "nothing", content length of zero.
       * An indefinite-length encoding is not alloweed.
       */
      if (state->contents_length || state->indefinite) {
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          break;
      }
      if (state->dest != NULL) {
          item = (SECItem *)(state->dest);
          item->data = NULL;
          item->len = 0;
      }
      state->place = afterEndOfContents;
      break;

      case SEC_ASN1_BMP_STRING:
      /* Error if length is not divisable by 2 */
      if (state->contents_length % 2) {
         PORT_SetError (SEC_ERROR_BAD_DER);
         state->top->status = decodeError;
         break;
      }   
      /* otherwise, handle as other string types */
      goto regular_string_type;

      case SEC_ASN1_UNIVERSAL_STRING:
      /* Error if length is not divisable by 4 */
      if (state->contents_length % 4) {
         PORT_SetError (SEC_ERROR_BAD_DER);
         state->top->status = decodeError;
         break;
      }   
      /* otherwise, handle as other string types */
      goto regular_string_type;

      case SEC_ASN1_SKIP:
      case SEC_ASN1_ANY:
      case SEC_ASN1_ANY_CONTENTS:
      /*
       * These are not (necessarily) strings, but they need nearly
       * identical handling (especially when we need to deal with
       * constructed sub-pieces), so we pretend they are.
       */
      /* fallthru */
regular_string_type:
      case SEC_ASN1_BIT_STRING:
      case SEC_ASN1_IA5_STRING:
      case SEC_ASN1_OCTET_STRING:
      case SEC_ASN1_PRINTABLE_STRING:
      case SEC_ASN1_T61_STRING:
      case SEC_ASN1_UTC_TIME:
      case SEC_ASN1_UTF8_STRING:
      case SEC_ASN1_VISIBLE_STRING:
      /*
       * We are allocating for a primitive or a constructed string.
       * If it is a constructed string, it may also be indefinite-length.
       * If it is primitive, the length can (legally) be zero.
       * Our first order of business is to allocate the memory for
       * the string, if we can (if we know the length).
       */
      item = (SECItem *)(state->dest);

      /*
       * If the item is a definite-length constructed string, then
       * the contents_length is actually larger than what we need
       * (because it also counts each intermediate header which we
       * will be throwing away as we go), but it is a perfectly good
       * upper bound that we just allocate anyway, and then concat
       * as we go; we end up wasting a few extra bytes but save a
       * whole other copy.
       */
      alloc_len = state->contents_length;
      poolp = NULL;     /* quiet compiler warnings about unused... */

      if (item == NULL || state->top->filter_only) {
          if (item != NULL) {
            item->data = NULL;
            item->len = 0;
          }
          alloc_len = 0;
      } else if (state->substring) {
          /*
           * If we are a substring of a constructed string, then we may
           * not have to allocate anything (because our parent, the
           * actual constructed string, did it for us).  If we are a
           * substring and we *do* have to allocate, that means our
           * parent is an indefinite-length, so we allocate from our pool;
           * later our parent will copy our string into the aggregated
           * whole and free our pool allocation.
           */
          if (item->data == NULL) {
            PORT_Assert (item->len == 0);
            poolp = state->top->our_pool;
          } else {
            alloc_len = 0;
          }
      } else {
          item->len = 0;
          item->data = NULL;
          poolp = state->top->their_pool;
      }

      if (alloc_len || ((! state->indefinite)
                    && (state->subitems_head != NULL))) {
          struct subitem *subitem;
          int len;

          PORT_Assert (item);
          if (!item) {
            PORT_SetError (SEC_ERROR_BAD_DER);
            state->top->status = decodeError;
            return;
          }
          PORT_Assert (item->len == 0 && item->data == NULL);
          /*
           * Check for and handle an ANY which has stashed aside the
           * header (identifier and length) bytes for us to include
           * in the saved contents.
           */
          if (state->subitems_head != NULL) {
            PORT_Assert (state->underlying_kind == SEC_ASN1_ANY);
            for (subitem = state->subitems_head;
                 subitem != NULL; subitem = subitem->next)
                alloc_len += subitem->len;
          }

          item->data = (unsigned char*)sec_asn1d_zalloc (poolp, alloc_len);
          if (item->data == NULL) {
            state->top->status = decodeError;
            break;
          }

          len = 0;
          for (subitem = state->subitems_head;
             subitem != NULL; subitem = subitem->next) {
            PORT_Memcpy (item->data + len, subitem->data, subitem->len);
            len += subitem->len;
          }
          item->len = len;

          /*
           * Because we use arenas and have a mark set, we later free
           * everything we have allocated, so this does *not* present
           * a memory leak (it is just temporarily left dangling).
           */
          state->subitems_head = state->subitems_tail = NULL;
      }

      if (state->contents_length == 0 && (! state->indefinite)) {
          /*
           * A zero-length simple or constructed string; we are done.
           */
          state->place = afterEndOfContents;
      } else if (state->found_tag_modifiers & SEC_ASN1_CONSTRUCTED) {
          const SEC_ASN1Template *sub;

          switch (state->underlying_kind) {
            case SEC_ASN1_ANY:
            case SEC_ASN1_ANY_CONTENTS:
            sub = SEC_AnyTemplate;
            break;
            case SEC_ASN1_BIT_STRING:
            sub = SEC_BitStringTemplate;
            break;
            case SEC_ASN1_BMP_STRING:
            sub = SEC_BMPStringTemplate;
            break;
            case SEC_ASN1_GENERALIZED_TIME:
            sub = SEC_GeneralizedTimeTemplate;
            break;
            case SEC_ASN1_IA5_STRING:
            sub = SEC_IA5StringTemplate;
            break;
            case SEC_ASN1_OCTET_STRING:
            sub = SEC_OctetStringTemplate;
            break;
            case SEC_ASN1_PRINTABLE_STRING:
            sub = SEC_PrintableStringTemplate;
            break;
            case SEC_ASN1_T61_STRING:
            sub = SEC_T61StringTemplate;
            break;
            case SEC_ASN1_UNIVERSAL_STRING:
            sub = SEC_UniversalStringTemplate;
            break;
            case SEC_ASN1_UTC_TIME:
            sub = SEC_UTCTimeTemplate;
            break;
            case SEC_ASN1_UTF8_STRING:
            sub = SEC_UTF8StringTemplate;
            break;
            case SEC_ASN1_VISIBLE_STRING:
            sub = SEC_VisibleStringTemplate;
            break;
            case SEC_ASN1_SKIP:
            sub = SEC_SkipTemplate;
            break;
            default:          /* redundant given outer switch cases, but */
            PORT_Assert(0);   /* the compiler does not seem to know that, */
            sub = NULL; /* so just do enough to quiet it. */
            break;
          }

          state->place = duringConstructedString;
          state = sec_asn1d_push_state (state->top, sub, item, PR_TRUE);
          if (state != NULL) {
            state->substring = PR_TRUE;   /* XXX propogate? */
            state = sec_asn1d_init_state_based_on_template (state);
          }
      } else if (state->indefinite) {
          /*
           * An indefinite-length string *must* be constructed!
           */
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
      } else {
          /*
           * A non-zero-length simple string.
           */
          if (state->underlying_kind == SEC_ASN1_BIT_STRING)
            state->place = beforeBitString;
          else
            state->place = duringLeaf;
      }
      break;

      default:
      /*
       * We are allocating for a simple leaf item.
       */
      if (state->contents_length) {
          if (state->dest != NULL) {
            item = (SECItem *)(state->dest);
            item->len = 0;
            if (state->top->filter_only) {
                item->data = NULL;
            } else {
                item->data = (unsigned char*)
                              sec_asn1d_zalloc (state->top->their_pool,
                                       state->contents_length);
                if (item->data == NULL) {
                  state->top->status = decodeError;
                  return;
                }
            }
          }
          state->place = duringLeaf;
      } else {
          /*
           * An indefinite-length or zero-length item is not allowed.
           * (All legal cases of such were handled above.)
           */
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
      }
    }
}


static void
sec_asn1d_free_child (sec_asn1d_state *state, PRBool error)
{
    if (state->child != NULL) {
      PORT_Assert (error || state->child->consumed == 0);
      PORT_Assert (state->our_mark != NULL);
      PORT_ArenaZRelease (state->top->our_pool, state->our_mark);
      if (error && state->top->their_pool == NULL) {
          /*
           * XXX We need to free anything allocated.
             * At this point, we failed in the middle of decoding. But we
             * can't free the data we previously allocated with PR_Malloc
             * unless we keep track of every pointer. So instead we have a
             * memory leak when decoding fails half-way, unless an arena is
             * used. See bug 95311 .
           */
      }
      state->child = NULL;
      state->our_mark = NULL;
    } else {
      /*
       * It is important that we do not leave a mark unreleased/unmarked.
       * But I do not think we should ever have one set in this case, only
       * if we had a child (handled above).  So check for that.  If this
       * assertion should ever get hit, then we probably need to add code
       * here to release back to our_mark (and then set our_mark to NULL).
       */
      PORT_Assert (state->our_mark == NULL);
    }
    state->place = beforeEndOfContents;
}

/* We have just saved an entire encoded ASN.1 object (type) for a SAVE 
** template, and now in the next template, we are going to decode that 
** saved data  by calling SEC_ASN1DecoderUpdate recursively.
** If that recursive call fails with needBytes, it is a fatal error,
** because the encoded object should have been complete.
** If that recursive call fails with decodeError, it will have already
** cleaned up the state stack, so we must bail out quickly.
**
** These checks of the status returned by the recursive call are now
** done in the caller of this function, immediately after it returns.
*/
static void
sec_asn1d_reuse_encoding (sec_asn1d_state *state)
{
    sec_asn1d_state *child;
    unsigned long consumed;
    SECItem *item;
    void *dest;


    child = state->child;
    PORT_Assert (child != NULL);

    consumed = child->consumed;
    child->consumed = 0;

    item = (SECItem *)(state->dest);
    PORT_Assert (item != NULL);

    PORT_Assert (item->len == consumed);

    /*
     * Free any grandchild.
     */
    sec_asn1d_free_child (child, PR_FALSE);

    /*
     * Notify after the SAVE field.
     */
    sec_asn1d_notify_after (state->top, state->dest, state->depth);

    /*
     * Adjust to get new dest and move forward.
     */
    dest = (char *)state->dest - state->theTemplate->offset;
    state->theTemplate++;
    child->dest = (char *)dest + state->theTemplate->offset;
    child->theTemplate = state->theTemplate;

    /*
     * Notify before the "real" field.
     */
    PORT_Assert (state->depth == child->depth);
    sec_asn1d_notify_before (state->top, child->dest, child->depth);

    /*
     * This will tell DecoderUpdate to return when it is done.
     */
    state->place = afterSaveEncoding;

    /*
     * We already have a child; "push" it by making it current.
     */
    state->top->current = child;

    /*
     * And initialize it so it is ready to parse.
     */
    (void) sec_asn1d_init_state_based_on_template(child);

    /*
     * Now parse that out of our data.
     */
    if (SEC_ASN1DecoderUpdate (state->top,
                         (char *) item->data, item->len) != SECSuccess)
      return;
    if (state->top->status == needBytes) {
      return;
    }

    PORT_Assert (state->top->current == state);
    PORT_Assert (state->child == child);

    /*
     * That should have consumed what we consumed before.
     */
    PORT_Assert (consumed == child->consumed);
    child->consumed = 0;

    /*
     * Done.
     */
    state->consumed += consumed;
    child->place = notInUse;
    state->place = afterEndOfContents;
}


static unsigned long
sec_asn1d_parse_leaf (sec_asn1d_state *state,
                  const char *buf, unsigned long len)
{
    SECItem *item;
    unsigned long bufLen;

    if (len == 0) {
      state->top->status = needBytes;
      return 0;
    }

    if (state->pending < len)
      len = state->pending;

    bufLen = len;

    item = (SECItem *)(state->dest);
    if (item != NULL && item->data != NULL) {
      /* Strip leading zeroes when target is unsigned integer */
      if (state->underlying_kind == SEC_ASN1_INTEGER && /* INTEGER   */
          item->len == 0 &&                             /* MSB       */
          item->type == siUnsignedInteger)              /* unsigned  */
      {
          while (len > 1 && buf[0] == 0) {              /* leading 0 */
            buf++;
            len--;
          }
      }
      PORT_Memcpy (item->data + item->len, buf, len);
      item->len += len;
    }
    state->pending -= bufLen;
    if (state->pending == 0)
      state->place = beforeEndOfContents;

    return bufLen;
}


static unsigned long
sec_asn1d_parse_bit_string (sec_asn1d_state *state,
                      const char *buf, unsigned long len)
{
    unsigned char byte;

    /*PORT_Assert (state->pending > 0); */
    PORT_Assert (state->place == beforeBitString);

    if (state->pending == 0) {
      if (state->dest != NULL) {
          SECItem *item = (SECItem *)(state->dest);
          item->data = NULL;
          item->len = 0;
          state->place = beforeEndOfContents;
          return 0;
      }
    }

    if (len == 0) {
      state->top->status = needBytes;
      return 0;
    }

    byte = (unsigned char) *buf;
    if (byte > 7) {
      PORT_SetError (SEC_ERROR_BAD_DER);
      state->top->status = decodeError;
      return 0;
    }

    state->bit_string_unused_bits = byte;
    state->place = duringBitString;
    state->pending -= 1;

    return 1;
}


static unsigned long
sec_asn1d_parse_more_bit_string (sec_asn1d_state *state,
                         const char *buf, unsigned long len)
{
    PORT_Assert (state->place == duringBitString);
    if (state->pending == 0) {
      /* An empty bit string with some unused bits is invalid. */
      if (state->bit_string_unused_bits) {
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
      } else {
          /* An empty bit string with no unused bits is OK. */
          state->place = beforeEndOfContents;
      }
      return 0;
    }

    len = sec_asn1d_parse_leaf (state, buf, len);
    if (state->place == beforeEndOfContents && state->dest != NULL) {
      SECItem *item;

      item = (SECItem *)(state->dest);
      if (item->len)
          item->len = (item->len << 3) - state->bit_string_unused_bits;
    }

    return len;
}


/*
 * XXX All callers should be looking at return value to detect
 * out-of-memory errors (and stop!).
 */
static struct subitem *
sec_asn1d_add_to_subitems (sec_asn1d_state *state,
                     const void *data, unsigned long len,
                     PRBool copy_data)
{
    struct subitem *thing;

    thing = (struct subitem*)sec_asn1d_zalloc (state->top->our_pool,
                        sizeof (struct subitem));
    if (thing == NULL) {
      state->top->status = decodeError;
      return NULL;
    }

    if (copy_data) {
      void *copy;
      copy = sec_asn1d_alloc (state->top->our_pool, len);
      if (copy == NULL) {
          state->top->status = decodeError;
          if (!state->top->our_pool)
            PORT_Free(thing);
          return NULL;
      }
      PORT_Memcpy (copy, data, len);
      thing->data = copy;
    } else {
      thing->data = data;
    }
    thing->len = len;
    thing->next = NULL;

    if (state->subitems_head == NULL) {
      PORT_Assert (state->subitems_tail == NULL);
      state->subitems_head = state->subitems_tail = thing;
    } else {
      state->subitems_tail->next = thing;
      state->subitems_tail = thing;
    }

    return thing;
}


static void
sec_asn1d_record_any_header (sec_asn1d_state *state,
                       const char *buf,
                       unsigned long len)
{
    SECItem *item;

    item = (SECItem *)(state->dest);
    if (item != NULL && item->data != NULL) {
      PORT_Assert (state->substring);
      PORT_Memcpy (item->data + item->len, buf, len);
      item->len += len;
    } else {
      sec_asn1d_add_to_subitems (state, buf, len, PR_TRUE);
    }
}


/*
 * We are moving along through the substrings of a constructed string,
 * and have just finished parsing one -- we need to save our child data
 * (if the child was not already writing directly into the destination)
 * and then move forward by one.
 *
 * We also have to detect when we are done:
 *    - a definite-length encoding stops when our pending value hits 0
 *    - an indefinite-length encoding stops when our child is empty
 *      (which means it was the end-of-contents octets)
 */
static void
sec_asn1d_next_substring (sec_asn1d_state *state)
{
    sec_asn1d_state *child;
    SECItem *item;
    unsigned long child_consumed;
    PRBool done;

    PORT_Assert (state->place == duringConstructedString);
    PORT_Assert (state->child != NULL);

    child = state->child;

    child_consumed = child->consumed;
    child->consumed = 0;
    state->consumed += child_consumed;

    done = PR_FALSE;

    if (state->pending) {
      PORT_Assert (!state->indefinite);
      if (child_consumed > state->pending) {
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          return;
      }

      state->pending -= child_consumed;
      if (state->pending == 0)
          done = PR_TRUE;
    } else {
      PORT_Assert (state->indefinite);

      item = (SECItem *)(child->dest);
      if (item != NULL && item->data != NULL) {
          /*
           * Save the string away for later concatenation.
           */
          PORT_Assert (item->data != NULL);
          sec_asn1d_add_to_subitems (state, item->data, item->len, PR_FALSE);
          /*
           * Clear the child item for the next round.
           */
          item->data = NULL;
          item->len = 0;
      }

      /*
       * If our child was just our end-of-contents octets, we are done.
       */
      if (child->endofcontents)
          done = PR_TRUE;
    }

    /*
     * Stop or do the next one.
     */
    if (done) {
      child->place = notInUse;
      state->place = afterConstructedString;
    } else {
      sec_asn1d_scrub_state (child);
      state->top->current = child;
    }
}


/*
 * We are doing a SET OF or SEQUENCE OF, and have just finished an item.
 */
static void
sec_asn1d_next_in_group (sec_asn1d_state *state)
{
    sec_asn1d_state *child;
    unsigned long child_consumed;

    PORT_Assert (state->place == duringGroup);
    PORT_Assert (state->child != NULL);

    child = state->child;

    child_consumed = child->consumed;
    child->consumed = 0;
    state->consumed += child_consumed;

    /*
     * If our child was just our end-of-contents octets, we are done.
     */
    if (child->endofcontents) {
      /* XXX I removed the PORT_Assert (child->dest == NULL) because there
       * was a bug in that a template that was a sequence of which also had
       * a child of a sequence of, in an indefinite group was not working 
       * properly.  This fix seems to work, (added the if statement below),
       * and nothing appears broken, but I am putting this note here just
       * in case. */
      /*
       * XXX No matter how many times I read that comment,
       * I cannot figure out what case he was fixing.  I believe what he
       * did was deliberate, so I am loathe to touch it.  I need to
       * understand how it could ever be that child->dest != NULL but
       * child->endofcontents is true, and why it is important to check
       * that state->subitems_head is NULL.  This really needs to be
       * figured out, as I am not sure if the following code should be
       * compensating for "offset", as is done a little farther below
       * in the more normal case.
       */
      PORT_Assert (state->indefinite);
      PORT_Assert (state->pending == 0);
      if(child->dest && !state->subitems_head) {
          sec_asn1d_add_to_subitems (state, child->dest, 0, PR_FALSE);
          child->dest = NULL;
      }

      child->place = notInUse;
      state->place = afterGroup;
      return;
    }

    /* 
     * Do the "after" field notification for next in group.
     */
    sec_asn1d_notify_after (state->top, child->dest, child->depth);

    /*
     * Save it away (unless we are not storing).
     */
    if (child->dest != NULL) {
      void *dest;

      dest = child->dest;
      dest = (char *)dest - child->theTemplate->offset;
      sec_asn1d_add_to_subitems (state, dest, 0, PR_FALSE);
      child->dest = NULL;
    }

    /*
     * Account for those bytes; see if we are done.
     */
    if (state->pending) {
      PORT_Assert (!state->indefinite);
      if (child_consumed > state->pending) {
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          return;
      }

      state->pending -= child_consumed;
      if (state->pending == 0) {
          child->place = notInUse;
          state->place = afterGroup;
          return;
      }
    }

    /*
     * Do the "before" field notification for next item in group.
     */
    sec_asn1d_notify_before (state->top, child->dest, child->depth);

    /*
     * Now we do the next one.
     */
    sec_asn1d_scrub_state (child);

    /* Initialize child state from the template */
    sec_asn1d_init_state_based_on_template(child);

    state->top->current = child;
}


/*
 * We are moving along through a sequence; move forward by one,
 * (detecting end-of-sequence when it happens).
 * XXX The handling of "missing" is ugly.  Fix it.
 */
static void
sec_asn1d_next_in_sequence (sec_asn1d_state *state)
{
    sec_asn1d_state *child;
    unsigned long child_consumed;
    PRBool child_missing;

    PORT_Assert (state->place == duringSequence);
    PORT_Assert (state->child != NULL);

    child = state->child;

    /*
     * Do the "after" field notification.
     */
    sec_asn1d_notify_after (state->top, child->dest, child->depth);

    child_missing = (PRBool) child->missing;
    child_consumed = child->consumed;
    child->consumed = 0;

    /*
     * Take care of accounting.
     */
    if (child_missing) {
      PORT_Assert (child->optional);
    } else {
      state->consumed += child_consumed;
      /*
       * Free any grandchild.
       */
      sec_asn1d_free_child (child, PR_FALSE);
      if (state->pending) {
          PORT_Assert (!state->indefinite);
          if (child_consumed > state->pending) {
            PORT_SetError (SEC_ERROR_BAD_DER);
            state->top->status = decodeError;
            return;
          }
          state->pending -= child_consumed;
          if (state->pending == 0) {
            child->theTemplate++;
            while (child->theTemplate->kind != 0) {
                if ((child->theTemplate->kind & SEC_ASN1_OPTIONAL) == 0) {
                  PORT_SetError (SEC_ERROR_BAD_DER);
                  state->top->status = decodeError;
                  return;
                }
                child->theTemplate++;
            }
            child->place = notInUse;
            state->place = afterEndOfContents;
            return;
          }
      }
    }

    /*
     * Move forward.
     */
    child->theTemplate++;
    if (child->theTemplate->kind == 0) {
      /*
       * We are done with this sequence.
       */
      child->place = notInUse;
      if (state->pending) {
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
      } else if (child_missing) {
          /*
           * We got to the end, but have a child that started parsing
           * and ended up "missing".  The only legitimate reason for
           * this is that we had one or more optional fields at the
           * end of our sequence, and we were encoded indefinite-length,
           * so when we went looking for those optional fields we
           * found our end-of-contents octets instead.
           * (Yes, this is ugly; dunno a better way to handle it.)
           * So, first confirm the situation, and then mark that we
           * are done.
           */
          if (state->indefinite && child->endofcontents) {
            PORT_Assert (child_consumed == 2);
            if (child_consumed != 2) {
                PORT_SetError (SEC_ERROR_BAD_DER);
                state->top->status = decodeError;
            } else {
                state->consumed += child_consumed;
                state->place = afterEndOfContents;
            }
          } else {
            PORT_SetError (SEC_ERROR_BAD_DER);
            state->top->status = decodeError;
          }
      } else {
          /*
           * We have to finish out, maybe reading end-of-contents octets;
           * let the normal logic do the right thing.
           */
          state->place = beforeEndOfContents;
      }
    } else {
      unsigned char child_found_tag_modifiers = 0;
      unsigned long child_found_tag_number = 0;

      /*
       * Reset state and push.
       */
      if (state->dest != NULL)
          child->dest = (char *)state->dest + child->theTemplate->offset;

      /*
       * Do the "before" field notification.
       */
      sec_asn1d_notify_before (state->top, child->dest, child->depth);

      if (child_missing) { /* if previous child was missing, copy the tag data we already have */
          child_found_tag_modifiers = child->found_tag_modifiers;
          child_found_tag_number = child->found_tag_number;
      }
      state->top->current = child;
      child = sec_asn1d_init_state_based_on_template (child);
      if (child_missing && child) {
          child->place = afterIdentifier;
          child->found_tag_modifiers = child_found_tag_modifiers;
          child->found_tag_number = child_found_tag_number;
          child->consumed = child_consumed;
          if (child->underlying_kind == SEC_ASN1_ANY
            && !child->top->filter_only) {
            /*
             * If the new field is an ANY, and we are storing, then
             * we need to save the tag out.  We would have done this
             * already in the normal case, but since we were looking
             * for an optional field, and we did not find it, we only
             * now realize we need to save the tag.
             */
            unsigned char identifier;

            /*
             * Check that we did not end up with a high tag; for that
             * we need to re-encode the tag into multiple bytes in order
             * to store it back to look like what we parsed originally.
             * In practice this does not happen, but for completeness
             * sake it should probably be made to work at some point.
             */
            PORT_Assert (child_found_tag_number < SEC_ASN1_HIGH_TAG_NUMBER);
            identifier = (unsigned char)(child_found_tag_modifiers | child_found_tag_number);
            sec_asn1d_record_any_header (child, (char *) &identifier, 1);
          }
      }
    }
}


static void
sec_asn1d_concat_substrings (sec_asn1d_state *state)
{
    PORT_Assert (state->place == afterConstructedString);

    if (state->subitems_head != NULL) {
      struct subitem *substring;
      unsigned long alloc_len, item_len;
      unsigned char *where;
      SECItem *item;
      PRBool is_bit_string;

      item_len = 0;
      is_bit_string = (state->underlying_kind == SEC_ASN1_BIT_STRING)
                  ? PR_TRUE : PR_FALSE;

      substring = state->subitems_head;
      while (substring != NULL) {
          /*
           * All bit-string substrings except the last one should be
           * a clean multiple of 8 bits.
           */
          if (is_bit_string && (substring->next == NULL)
                        && (substring->len & 0x7)) {
            PORT_SetError (SEC_ERROR_BAD_DER);
            state->top->status = decodeError;
            return;
          }
          item_len += substring->len;
          substring = substring->next;
      }

      if (is_bit_string) {
#ifdef XP_WIN16         /* win16 compiler gets an internal error otherwise */
          alloc_len = (((long)item_len + 7) / 8);
#else
          alloc_len = ((item_len + 7) >> 3);
#endif
      } else {
          /*
           * Add 2 for the end-of-contents octets of an indefinite-length
           * ANY that is *not* also an INNER.  Because we zero-allocate
           * below, all we need to do is increase the length here.
           */
          if (state->underlying_kind == SEC_ASN1_ANY && state->indefinite)
            item_len += 2; 
          alloc_len = item_len;
      }

      item = (SECItem *)(state->dest);
      PORT_Assert (item != NULL);
      PORT_Assert (item->data == NULL);
      item->data = (unsigned char*)sec_asn1d_zalloc (state->top->their_pool, 
                                           alloc_len);
      if (item->data == NULL) {
          state->top->status = decodeError;
          return;
      }
      item->len = item_len;

      where = item->data;
      substring = state->subitems_head;
      while (substring != NULL) {
          if (is_bit_string)
            item_len = (substring->len + 7) >> 3;
          else
            item_len = substring->len;
          PORT_Memcpy (where, substring->data, item_len);
          where += item_len;
          substring = substring->next;
      }

      /*
       * Because we use arenas and have a mark set, we later free
       * everything we have allocated, so this does *not* present
       * a memory leak (it is just temporarily left dangling).
       */
      state->subitems_head = state->subitems_tail = NULL;
    }

    state->place = afterEndOfContents;
}


static void
sec_asn1d_concat_group (sec_asn1d_state *state)
{
    const void ***placep;

    PORT_Assert (state->place == afterGroup);

    placep = (const void***)state->dest;
    PORT_Assert(state->subitems_head == NULL || placep != NULL);
    if (placep != NULL) {
      struct subitem *item;
      const void **group;
      int count;

      count = 0;
      item = state->subitems_head;
      while (item != NULL) {
          PORT_Assert (item->next != NULL || item == state->subitems_tail);
          count++;
          item = item->next;
      }

      group = (const void**)sec_asn1d_zalloc (state->top->their_pool,
                          (count + 1) * (sizeof(void *)));
      if (group == NULL) {
          state->top->status = decodeError;
          return;
      }

      *placep = group;

      item = state->subitems_head;
      while (item != NULL) {
          *group++ = item->data;
          item = item->next;
      }
      *group = NULL;

      /*
       * Because we use arenas and have a mark set, we later free
       * everything we have allocated, so this does *not* present
       * a memory leak (it is just temporarily left dangling).
       */
      state->subitems_head = state->subitems_tail = NULL;
    }

    state->place = afterEndOfContents;
}


/*
 * For those states that push a child to handle a subtemplate,
 * "absorb" that child (transfer necessary information).
 */
static void
sec_asn1d_absorb_child (sec_asn1d_state *state)
{
    /*
     * There is absolutely supposed to be a child there.
     */
    PORT_Assert (state->child != NULL);

    /*
     * Inherit the missing status of our child, and do the ugly
     * backing-up if necessary.
     */
    state->missing = state->child->missing;
    if (state->missing) {
      state->found_tag_number = state->child->found_tag_number;
      state->found_tag_modifiers = state->child->found_tag_modifiers;
      state->endofcontents = state->child->endofcontents;
    }

    /*
     * Add in number of bytes consumed by child.
     * (Only EXPLICIT should have already consumed bytes itself.)
     */
    PORT_Assert (state->place == afterExplicit || state->consumed == 0);
    state->consumed += state->child->consumed;

    /*
     * Subtract from bytes pending; this only applies to a definite-length
     * EXPLICIT field.
     */
    if (state->pending) {
      PORT_Assert (!state->indefinite);
      PORT_Assert (state->place == afterExplicit);

      /*
       * If we had a definite-length explicit, then what the child
       * consumed should be what was left pending.
       */
      if (state->pending != state->child->consumed) {
          if (state->pending < state->child->consumed) {
            PORT_SetError (SEC_ERROR_BAD_DER);
            state->top->status = decodeError;
            return;
          }
          /*
           * Okay, this is a hack.  It *should* be an error whether
           * pending is too big or too small, but it turns out that
           * we had a bug in our *old* DER encoder that ended up
           * counting an explicit header twice in the case where
           * the underlying type was an ANY.  So, because we cannot
           * prevent receiving these (our own certificate server can
           * send them to us), we need to be lenient and accept them.
           * To do so, we need to pretend as if we read all of the
           * bytes that the header said we would find, even though
           * we actually came up short.
           */
          state->consumed += (state->pending - state->child->consumed);
      }
      state->pending = 0;
    }

    /*
     * Indicate that we are done with child.
     */
    state->child->consumed = 0;

    /*
     * And move on to final state.
     * (Technically everybody could move to afterEndOfContents except
     * for an indefinite-length EXPLICIT; for simplicity though we assert
     * that but let the end-of-contents code do the real determination.)
     */
    PORT_Assert (state->place == afterExplicit || (! state->indefinite));
    state->place = beforeEndOfContents;
}


static void
sec_asn1d_prepare_for_end_of_contents (sec_asn1d_state *state)
{
    PORT_Assert (state->place == beforeEndOfContents);

    if (state->indefinite) {
      state->place = duringEndOfContents;
      state->pending = 2;
    } else {
      state->place = afterEndOfContents;
    }
}


static unsigned long
sec_asn1d_parse_end_of_contents (sec_asn1d_state *state,
                         const char *buf, unsigned long len)
{
    unsigned int i;

    PORT_Assert (state->pending <= 2);
    PORT_Assert (state->place == duringEndOfContents);

    if (len == 0) {
      state->top->status = needBytes;
      return 0;
    }

    if (state->pending < len)
      len = state->pending;

    for (i = 0; i < len; i++) {
      if (buf[i] != 0) {
          /*
           * We expect to find only zeros; if not, just give up.
           */
          PORT_SetError (SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          return 0;
      }
    }

    state->pending -= len;

    if (state->pending == 0) {
      state->place = afterEndOfContents;
      state->endofcontents = PR_TRUE;
    }

    return len;
}


static void
sec_asn1d_pop_state (sec_asn1d_state *state)
{
#if 0 /* XXX I think this should always be handled explicitly by parent? */
    /*
     * Account for our child.
     */
    if (state->child != NULL) {
      state->consumed += state->child->consumed;
      if (state->pending) {
          PORT_Assert (!state->indefinite);
          if (state->child->consumed > state->pending) {
            PORT_SetError (SEC_ERROR_BAD_DER);
            state->top->status = decodeError;
          } else {
            state->pending -= state->child->consumed;
          }
      }
      state->child->consumed = 0;
    }
#endif      /* XXX */

    /*
     * Free our child.
     */
    sec_asn1d_free_child (state, PR_FALSE);

    /*
     * Just make my parent be the current state.  It will then clean
     * up after me and free me (or reuse me).
     */
    state->top->current = state->parent;
}

static sec_asn1d_state *
sec_asn1d_before_choice (sec_asn1d_state *state)
{
    sec_asn1d_state *child;

    if (state->allocate) {
      void *dest;

      dest = sec_asn1d_zalloc(state->top->their_pool, state->theTemplate->size);
      if ((void *)NULL == dest) {
          state->top->status = decodeError;
          return (sec_asn1d_state *)NULL;
      }

      state->dest = (char *)dest + state->theTemplate->offset;
    }

    child = sec_asn1d_push_state(state->top, state->theTemplate + 1, 
                         (char *)state->dest - state->theTemplate->offset, 
                         PR_FALSE);
    if ((sec_asn1d_state *)NULL == child) {
      return (sec_asn1d_state *)NULL;
    }

    sec_asn1d_scrub_state(child);
    child = sec_asn1d_init_state_based_on_template(child);
    if ((sec_asn1d_state *)NULL == child) {
      return (sec_asn1d_state *)NULL;
    }

    child->optional = PR_TRUE;

    state->place = duringChoice;

    return child;
}

static sec_asn1d_state *
sec_asn1d_during_choice (sec_asn1d_state *state)
{
    sec_asn1d_state *child = state->child;
    
    PORT_Assert((sec_asn1d_state *)NULL != child);

    if (child->missing) {
      unsigned char child_found_tag_modifiers = 0;
      unsigned long child_found_tag_number = 0;
      void *        dest;

      state->consumed += child->consumed;

      if (child->endofcontents) {
          /* This choice is probably the first item in a GROUP
          ** (e.g. SET_OF) that was indefinite-length encoded.
          ** We're actually at the end of that GROUP.
          ** We look up the stack to be sure that we find
          ** a state with indefinite length encoding before we
          ** find a state (like a SEQUENCE) that is definite.
          */
          child->place = notInUse;
          state->place = afterChoice;
          state->endofcontents = PR_TRUE;  /* propagate this up */
          if (sec_asn1d_parent_allows_EOC(state))
            return state;
          PORT_SetError(SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          return NULL;
      }

      dest = (char *)child->dest - child->theTemplate->offset;
      child->theTemplate++;

      if (0 == child->theTemplate->kind) {
          /* Ran out of choices */
          PORT_SetError(SEC_ERROR_BAD_DER);
          state->top->status = decodeError;
          return (sec_asn1d_state *)NULL;
      }
      child->dest = (char *)dest + child->theTemplate->offset;

      /* cargo'd from next_in_sequence innards */
      if (state->pending) {
          PORT_Assert(!state->indefinite);
          if (child->consumed > state->pending) {
            PORT_SetError (SEC_ERROR_BAD_DER);
            state->top->status = decodeError;
            return NULL;
          }
          state->pending -= child->consumed;
          if (0 == state->pending) {
            /* XXX uh.. not sure if I should have stopped this
             * from happening before. */
            PORT_Assert(0);
            PORT_SetError(SEC_ERROR_BAD_DER);
            state->top->status = decodeError;
            return (sec_asn1d_state *)NULL;
          }
      }

      child->consumed = 0;
      sec_asn1d_scrub_state(child);

      /* move it on top again */
      state->top->current = child;

      child_found_tag_modifiers = child->found_tag_modifiers;
      child_found_tag_number = child->found_tag_number;

      child = sec_asn1d_init_state_based_on_template(child);
      if ((sec_asn1d_state *)NULL == child) {
          return (sec_asn1d_state *)NULL;
      }

      /* copy our findings to the new top */
      child->found_tag_modifiers = child_found_tag_modifiers;
      child->found_tag_number = child_found_tag_number;

      child->optional = PR_TRUE;
      child->place = afterIdentifier;

      return child;
    } 
    if ((void *)NULL != state->dest) {
      /* Store the enum */
      int *which = (int *)state->dest;
      *which = (int)child->theTemplate->size;
    }

    child->place = notInUse;

    state->place = afterChoice;
    return state;
}

static void
sec_asn1d_after_choice (sec_asn1d_state *state)
{
    state->consumed += state->child->consumed;
    state->child->consumed = 0;
    state->place = afterEndOfContents;
    sec_asn1d_pop_state(state);
}

unsigned long
sec_asn1d_uinteger(SECItem *src)
{
    unsigned long value;
    int len;

    if (src->len > 5 || (src->len > 4 && src->data[0] == 0))
      return 0;

    value = 0;
    len = src->len;
    while (len) {
      value <<= 8;
      value |= src->data[--len];
    }
    return value;
}

SECStatus
SEC_ASN1DecodeInteger(SECItem *src, unsigned long *value)
{
    unsigned long v;
    unsigned int i;
    
    if (src == NULL) {
      PORT_SetError(SEC_ERROR_INVALID_ARGS);
      return SECFailure;
    }

    if (src->len > sizeof(unsigned long)) {
      PORT_SetError(SEC_ERROR_INVALID_ARGS);
      return SECFailure;
    }

    if (src->data == NULL) {
      PORT_SetError(SEC_ERROR_INVALID_ARGS);
      return SECFailure;
    }

    if (src->data[0] & 0x80)
      v = -1;           /* signed and negative - start with all 1's */
    else
      v = 0;

    for (i= 0; i < src->len; i++) {
      /* shift in next byte */
      v <<= 8;
      v |= src->data[i];
    }
    *value = v;
    return SECSuccess;
}

#ifdef DEBUG_ASN1D_STATES
static void
dump_states(SEC_ASN1DecoderContext *cx)
{
    sec_asn1d_state *state;
    char kindBuf[256];

    for (state = cx->current; state->parent; state = state->parent) {
        ;
    }

    for (; state; state = state->child) {
        int i;
        for (i = 0; i < state->depth; i++) {
            printf("  ");
        }

        i = formatKind(state->theTemplate->kind, kindBuf);
        printf("%s: tmpl %08x, kind%s",
               (state == cx->current) ? "STATE" : "State",
               state->theTemplate,
               kindBuf);
        printf(" %s", (state->place >= 0 && state->place <= notInUse)
                       ? place_names[ state->place ]
                       : "(undefined)");
        if (!i)
            printf(", expect 0x%02x",
                   state->expect_tag_number | state->expect_tag_modifiers);

        printf("%s%s%s %d\n",
               state->indefinite    ? ", indef"   : "",
               state->missing       ? ", miss"    : "",
               state->endofcontents ? ", EOC"     : "",
               state->pending
               );
    }

    return;
}
#endif /* DEBUG_ASN1D_STATES */

SECStatus
SEC_ASN1DecoderUpdate (SEC_ASN1DecoderContext *cx,
                   const char *buf, unsigned long len)
{
    sec_asn1d_state *state = NULL;
    unsigned long consumed;
    SEC_ASN1EncodingPart what;
    sec_asn1d_state *stateEnd = cx->current;

    if (cx->status == needBytes)
      cx->status = keepGoing;

    while (cx->status == keepGoing) {
      state = cx->current;
      what = SEC_ASN1_Contents;
      consumed = 0;
#ifdef DEBUG_ASN1D_STATES
        printf("\nPLACE = %s, next byte = 0x%02x, %08x[%d]\n",
               (state->place >= 0 && state->place <= notInUse) ?
               place_names[ state->place ] : "(undefined)",
               (unsigned int)((unsigned char *)buf)[ consumed ],
               buf, consumed);
        dump_states(cx);
#endif /* DEBUG_ASN1D_STATES */
      switch (state->place) {
        case beforeIdentifier:
          consumed = sec_asn1d_parse_identifier (state, buf, len);
          what = SEC_ASN1_Identifier;
          break;
        case duringIdentifier:
          consumed = sec_asn1d_parse_more_identifier (state, buf, len);
          what = SEC_ASN1_Identifier;
          break;
        case afterIdentifier:
          sec_asn1d_confirm_identifier (state);
          break;
        case beforeLength:
          consumed = sec_asn1d_parse_length (state, buf, len);
          what = SEC_ASN1_Length;
          break;
        case duringLength:
          consumed = sec_asn1d_parse_more_length (state, buf, len);
          what = SEC_ASN1_Length;
          break;
        case afterLength:
          sec_asn1d_prepare_for_contents (state);
          break;
        case beforeBitString:
          consumed = sec_asn1d_parse_bit_string (state, buf, len);
          break;
        case duringBitString:
          consumed = sec_asn1d_parse_more_bit_string (state, buf, len);
          break;
        case duringConstructedString:
          sec_asn1d_next_substring (state);
          break;
        case duringGroup:
          sec_asn1d_next_in_group (state);
          break;
        case duringLeaf:
          consumed = sec_asn1d_parse_leaf (state, buf, len);
          break;
        case duringSaveEncoding:
          sec_asn1d_reuse_encoding (state);
          if (cx->status == decodeError) {
            /* recursive call has already popped all states from stack.
            ** Bail out quickly.
            */
            return SECFailure;
          }
          if (cx->status == needBytes) {
            /* recursive call wanted more data. Fatal. Clean up below. */
            PORT_SetError (SEC_ERROR_BAD_DER);
            cx->status = decodeError;
          }
          break;
        case duringSequence:
          sec_asn1d_next_in_sequence (state);
          break;
        case afterConstructedString:
          sec_asn1d_concat_substrings (state);
          break;
        case afterExplicit:
        case afterImplicit:
        case afterInline:
        case afterPointer:
          sec_asn1d_absorb_child (state);
          break;
        case afterGroup:
          sec_asn1d_concat_group (state);
          break;
        case afterSaveEncoding:
          /* SEC_ASN1DecoderUpdate has called itself recursively to 
          ** decode SAVEd encoded data, and now is done decoding that.
          ** Return to the calling copy of SEC_ASN1DecoderUpdate.
          */
          return SECSuccess;
        case beforeEndOfContents:
          sec_asn1d_prepare_for_end_of_contents (state);
          break;
        case duringEndOfContents:
          consumed = sec_asn1d_parse_end_of_contents (state, buf, len);
          what = SEC_ASN1_EndOfContents;
          break;
        case afterEndOfContents:
          sec_asn1d_pop_state (state);
          break;
          case beforeChoice:
            state = sec_asn1d_before_choice(state);
            break;
          case duringChoice:
            state = sec_asn1d_during_choice(state);
            break;
          case afterChoice:
            sec_asn1d_after_choice(state);
            break;
        case notInUse:
        default:
          /* This is not an error, but rather a plain old BUG! */
          PORT_Assert (0);
          PORT_SetError (SEC_ERROR_BAD_DER);
          cx->status = decodeError;
          break;
      }

      if (cx->status == decodeError)
          break;

      /* We should not consume more than we have.  */
      PORT_Assert (consumed <= len);
      if (consumed > len) {
          PORT_SetError (SEC_ERROR_BAD_DER);
          cx->status = decodeError;
          break;
      }

      /* It might have changed, so we have to update our local copy.  */
      state = cx->current;

      /* If it is NULL, we have popped all the way to the top.  */
      if (state == NULL) {
          PORT_Assert (consumed == 0);
#if 0 /* XXX I want this here, but it seems that we have situations (like
       * downloading a pkcs7 cert chain from some issuers) that give us a
       * length which is greater than the entire encoding.  So, we cannot
       * have this be an error.
       */
          if (len > 0) {
            PORT_SetError (SEC_ERROR_BAD_DER);
            cx->status = decodeError;
          } else
#endif
            cx->status = allDone;
          break;
      }
      else if (state->theTemplate->kind == SEC_ASN1_SKIP_REST) {
          cx->status = allDone;
          break;
      }
        
      if (consumed == 0)
          continue;

      /*
       * The following check is specifically looking for an ANY
       * that is *not* also an INNER, because we need to save aside
       * all bytes in that case -- the contents parts will get
       * handled like all other contents, and the end-of-contents
       * bytes are added by the concat code, but the outer header
       * bytes need to get saved too, so we do them explicitly here.
       */
      if (state->underlying_kind == SEC_ASN1_ANY
          && !cx->filter_only && (what == SEC_ASN1_Identifier
                            || what == SEC_ASN1_Length)) {
          sec_asn1d_record_any_header (state, buf, consumed);
      }

      /*
       * We had some number of good, accepted bytes.  If the caller
       * has registered to see them, pass them along.
       */
      if (state->top->filter_proc != NULL) {
          int depth;

          depth = state->depth;
          if (what == SEC_ASN1_EndOfContents && !state->indefinite) {
            PORT_Assert (state->parent != NULL
                       && state->parent->indefinite);
            depth--;
            PORT_Assert (depth == state->parent->depth);
          }
          (* state->top->filter_proc) (state->top->filter_arg,
                               buf, consumed, depth, what);
      }

      state->consumed += consumed;
      buf += consumed;
      len -= consumed;
    }

    if (cx->status == decodeError) {
      while (state != NULL && stateEnd->parent!=state) {
          sec_asn1d_free_child (state, PR_TRUE);
          state = state->parent;
      }
#ifdef SEC_ASN1D_FREE_ON_ERROR      /*
                         * XXX This does not work because we can
                         * end up leaving behind dangling pointers
                         * to stuff that was allocated.  In order
                         * to make this really work (which would
                         * be a good thing, I think), we need to
                         * keep track of every place/pointer that
                         * was allocated and make sure to NULL it
                         * out before we then free back to the mark.    
                         */
      if (cx->their_pool != NULL) {
          PORT_Assert (cx->their_mark != NULL);
          PORT_ArenaRelease (cx->their_pool, cx->their_mark);
      }
#endif
      return SECFailure;
    }

#if 0 /* XXX This is what I want, but cannot have because it seems we
       * have situations (like when downloading a pkcs7 cert chain from
       * some issuers) that give us a total length which is greater than
       * the entire encoding.  So, we have to allow allDone to have a
       * remaining length greater than zero.  I wanted to catch internal
       * bugs with this, noticing when we do not have the right length.
       * Oh well.
       */
    PORT_Assert (len == 0
             && (cx->status == needBytes || cx->status == allDone));
#else
    PORT_Assert ((len == 0 && cx->status == needBytes)
             || cx->status == allDone);
#endif
    return SECSuccess;
}


SECStatus
SEC_ASN1DecoderFinish (SEC_ASN1DecoderContext *cx)
{
    SECStatus rv;

    if (cx->status == needBytes) {
      PORT_SetError (SEC_ERROR_BAD_DER);
      rv = SECFailure;
    } else {
      rv = SECSuccess;
    }

    /*
     * XXX anything else that needs to be finished?
     */

    PORT_FreeArena (cx->our_pool, PR_TRUE);

    return rv;
}


SEC_ASN1DecoderContext *
SEC_ASN1DecoderStart (PRArenaPool *their_pool, void *dest,
                  const SEC_ASN1Template *theTemplate)
{
    PRArenaPool *our_pool;
    SEC_ASN1DecoderContext *cx;

    our_pool = PORT_NewArena (SEC_ASN1_DEFAULT_ARENA_SIZE);
    if (our_pool == NULL)
      return NULL;

    cx = (SEC_ASN1DecoderContext*)PORT_ArenaZAlloc (our_pool, sizeof(*cx));
    if (cx == NULL) {
      PORT_FreeArena (our_pool, PR_FALSE);
      return NULL;
    }

    cx->our_pool = our_pool;
    if (their_pool != NULL) {
      cx->their_pool = their_pool;
#ifdef SEC_ASN1D_FREE_ON_ERROR
      cx->their_mark = PORT_ArenaMark (their_pool);
#endif
    }

    cx->status = needBytes;

    if (sec_asn1d_push_state(cx, theTemplate, dest, PR_FALSE) == NULL
      || sec_asn1d_init_state_based_on_template (cx->current) == NULL) {
      /*
       * Trouble initializing (probably due to failed allocations)
       * requires that we just give up.
       */
      PORT_FreeArena (our_pool, PR_FALSE);
      return NULL;
    }

    return cx;
}


void
SEC_ASN1DecoderSetFilterProc (SEC_ASN1DecoderContext *cx,
                        SEC_ASN1WriteProc fn, void *arg,
                        PRBool only)
{
    /* check that we are "between" fields here */
    PORT_Assert (cx->during_notify);

    cx->filter_proc = fn;
    cx->filter_arg = arg;
    cx->filter_only = only;
}


void
SEC_ASN1DecoderClearFilterProc (SEC_ASN1DecoderContext *cx)
{
    /* check that we are "between" fields here */
    PORT_Assert (cx->during_notify);

    cx->filter_proc = NULL;
    cx->filter_arg = NULL;
    cx->filter_only = PR_FALSE;
}


void
SEC_ASN1DecoderSetNotifyProc (SEC_ASN1DecoderContext *cx,
                        SEC_ASN1NotifyProc fn, void *arg)
{
    cx->notify_proc = fn;
    cx->notify_arg = arg;
}


void
SEC_ASN1DecoderClearNotifyProc (SEC_ASN1DecoderContext *cx)
{
    cx->notify_proc = NULL;
    cx->notify_arg = NULL;    /* not necessary; just being clean */
}

void
SEC_ASN1DecoderAbort(SEC_ASN1DecoderContext *cx, int error)
{
    PORT_Assert(cx);
    PORT_SetError(error);
    cx->status = decodeError;
}


SECStatus
SEC_ASN1Decode (PRArenaPool *poolp, void *dest,
            const SEC_ASN1Template *theTemplate,
            const char *buf, long len)
{
    SEC_ASN1DecoderContext *dcx;
    SECStatus urv, frv;

    dcx = SEC_ASN1DecoderStart (poolp, dest, theTemplate);
    if (dcx == NULL)
      return SECFailure;

    urv = SEC_ASN1DecoderUpdate (dcx, buf, len);
    frv = SEC_ASN1DecoderFinish (dcx);

    if (urv != SECSuccess)
      return urv;

    return frv;
}


SECStatus
SEC_ASN1DecodeItem (PRArenaPool *poolp, void *dest,
                const SEC_ASN1Template *theTemplate,
                const SECItem *src)
{
    return SEC_ASN1Decode (poolp, dest, theTemplate,
                     (const char *)src->data, src->len);
}

#ifdef DEBUG_ASN1D_STATES
void sec_asn1d_Assert(const char *s, const char *file, PRIntn ln)
{
    printf("Assertion failed, \"%s\", file %s, line %d\n", s, file, ln);
    fflush(stdout);
}
#endif

/*
 * Generic templates for individual/simple items and pointers to
 * and sets of same.
 *
 * If you need to add a new one, please note the following:
 *     - For each new basic type you should add *four* templates:
 *    one plain, one PointerTo, one SequenceOf and one SetOf.
 *     - If the new type can be constructed (meaning, it is a
 *    *string* type according to BER/DER rules), then you should
 *    or-in SEC_ASN1_MAY_STREAM to the type in the basic template.
 *    See the definition of the OctetString template for an example.
 *     - It may not be obvious, but these are in *alphabetical*
 *    order based on the SEC_ASN1_XXX name; so put new ones in
 *    the appropriate place.
 */

const SEC_ASN1Template SEC_SequenceOfAnyTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_AnyTemplate }
};

#if 0

const SEC_ASN1Template SEC_PointerToBitStringTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_BitStringTemplate }
};

const SEC_ASN1Template SEC_SequenceOfBitStringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_BitStringTemplate }
};

const SEC_ASN1Template SEC_SetOfBitStringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_BitStringTemplate }
};

const SEC_ASN1Template SEC_PointerToBMPStringTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_BMPStringTemplate }
};

const SEC_ASN1Template SEC_SequenceOfBMPStringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_BMPStringTemplate }
};

const SEC_ASN1Template SEC_SetOfBMPStringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_BMPStringTemplate }
};

const SEC_ASN1Template SEC_PointerToBooleanTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_BooleanTemplate }
};

const SEC_ASN1Template SEC_SequenceOfBooleanTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_BooleanTemplate }
};

const SEC_ASN1Template SEC_SetOfBooleanTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_BooleanTemplate }
};

#endif

const SEC_ASN1Template SEC_EnumeratedTemplate[] = {
    { SEC_ASN1_ENUMERATED, 0, NULL, sizeof(SECItem) }
};

const SEC_ASN1Template SEC_PointerToEnumeratedTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_EnumeratedTemplate }
};

#if 0

const SEC_ASN1Template SEC_SequenceOfEnumeratedTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_EnumeratedTemplate }
};

#endif

const SEC_ASN1Template SEC_SetOfEnumeratedTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_EnumeratedTemplate }
};

const SEC_ASN1Template SEC_PointerToGeneralizedTimeTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_GeneralizedTimeTemplate }
};

#if 0

const SEC_ASN1Template SEC_SequenceOfGeneralizedTimeTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_GeneralizedTimeTemplate }
};

const SEC_ASN1Template SEC_SetOfGeneralizedTimeTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_GeneralizedTimeTemplate }
};

const SEC_ASN1Template SEC_PointerToIA5StringTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_IA5StringTemplate }
};

const SEC_ASN1Template SEC_SequenceOfIA5StringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_IA5StringTemplate }
};

const SEC_ASN1Template SEC_SetOfIA5StringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_IA5StringTemplate }
};

const SEC_ASN1Template SEC_PointerToIntegerTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_IntegerTemplate }
};

const SEC_ASN1Template SEC_SequenceOfIntegerTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_IntegerTemplate }
};

const SEC_ASN1Template SEC_SetOfIntegerTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_IntegerTemplate }
};

const SEC_ASN1Template SEC_PointerToNullTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_NullTemplate }
};

const SEC_ASN1Template SEC_SequenceOfNullTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_NullTemplate }
};

const SEC_ASN1Template SEC_SetOfNullTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_NullTemplate }
};

const SEC_ASN1Template SEC_PointerToObjectIDTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_ObjectIDTemplate }
};

#endif

const SEC_ASN1Template SEC_SequenceOfObjectIDTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_ObjectIDTemplate }
};

#if 0

const SEC_ASN1Template SEC_SetOfObjectIDTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_ObjectIDTemplate }
};

const SEC_ASN1Template SEC_SequenceOfOctetStringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_OctetStringTemplate }
};

const SEC_ASN1Template SEC_SetOfOctetStringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_OctetStringTemplate }
};

#endif

const SEC_ASN1Template SEC_PrintableStringTemplate[] = {
    { SEC_ASN1_PRINTABLE_STRING | SEC_ASN1_MAY_STREAM, 0, NULL, sizeof(SECItem)}
};

#if 0

const SEC_ASN1Template SEC_PointerToPrintableStringTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_PrintableStringTemplate }
};

const SEC_ASN1Template SEC_SequenceOfPrintableStringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_PrintableStringTemplate }
};

const SEC_ASN1Template SEC_SetOfPrintableStringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_PrintableStringTemplate }
};

#endif

const SEC_ASN1Template SEC_T61StringTemplate[] = {
    { SEC_ASN1_T61_STRING | SEC_ASN1_MAY_STREAM, 0, NULL, sizeof(SECItem) }
};

#if 0

const SEC_ASN1Template SEC_PointerToT61StringTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_T61StringTemplate }
};

const SEC_ASN1Template SEC_SequenceOfT61StringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_T61StringTemplate }
};

const SEC_ASN1Template SEC_SetOfT61StringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_T61StringTemplate }
};

#endif

const SEC_ASN1Template SEC_UniversalStringTemplate[] = {
    { SEC_ASN1_UNIVERSAL_STRING | SEC_ASN1_MAY_STREAM, 0, NULL, sizeof(SECItem)}
};

#if 0

const SEC_ASN1Template SEC_PointerToUniversalStringTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_UniversalStringTemplate }
};

const SEC_ASN1Template SEC_SequenceOfUniversalStringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_UniversalStringTemplate }
};

const SEC_ASN1Template SEC_SetOfUniversalStringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_UniversalStringTemplate }
};

const SEC_ASN1Template SEC_PointerToUTCTimeTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_UTCTimeTemplate }
};

const SEC_ASN1Template SEC_SequenceOfUTCTimeTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_UTCTimeTemplate }
};

const SEC_ASN1Template SEC_SetOfUTCTimeTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_UTCTimeTemplate }
};

const SEC_ASN1Template SEC_PointerToUTF8StringTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_UTF8StringTemplate }
};

const SEC_ASN1Template SEC_SequenceOfUTF8StringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_UTF8StringTemplate }
};

const SEC_ASN1Template SEC_SetOfUTF8StringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_UTF8StringTemplate }
};

#endif

const SEC_ASN1Template SEC_VisibleStringTemplate[] = {
    { SEC_ASN1_VISIBLE_STRING | SEC_ASN1_MAY_STREAM, 0, NULL, sizeof(SECItem) }
};

#if 0

const SEC_ASN1Template SEC_PointerToVisibleStringTemplate[] = {
    { SEC_ASN1_POINTER, 0, SEC_VisibleStringTemplate }
};

const SEC_ASN1Template SEC_SequenceOfVisibleStringTemplate[] = {
    { SEC_ASN1_SEQUENCE_OF, 0, SEC_VisibleStringTemplate }
};

const SEC_ASN1Template SEC_SetOfVisibleStringTemplate[] = {
    { SEC_ASN1_SET_OF, 0, SEC_VisibleStringTemplate }
};

#endif

/*
 * Template for skipping a subitem.
 *
 * Note that it only makes sense to use this for decoding (when you want
 * to decode something where you are only interested in one or two of
 * the fields); you cannot encode a SKIP!
 */
const SEC_ASN1Template SEC_SkipTemplate[] = {
    { SEC_ASN1_SKIP }
};


/* These functions simply return the address of the above-declared templates.
** This is necessary for Windows DLLs.  Sigh.
*/
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_EnumeratedTemplate)
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_PointerToEnumeratedTemplate)
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_SequenceOfAnyTemplate)
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_SequenceOfObjectIDTemplate)
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_SkipTemplate)
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_UniversalStringTemplate)
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_PrintableStringTemplate)
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_T61StringTemplate)
SEC_ASN1_CHOOSER_IMPLEMENT(SEC_PointerToGeneralizedTimeTemplate)


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