The Tor Browser: security/nss/lib/util/secasn1e.c@6474c204b198 (annotated)

security/nss/lib/util/secasn1e.c@6474c204b198 (annotated)

security/nss/lib/util/secasn1e.c

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /*
  * Support for ENcoding ASN.1 data based on BER/DER (Basic/Distinguished
  * Encoding Rules).
  */
 #include "secasn1.h"
 typedef enum {
     beforeHeader,
     duringContents,
     duringGroup,
     duringSequence,
     afterContents,
     afterImplicit,
     afterInline,
     afterPointer,
     afterChoice,
     notInUse
 } sec_asn1e_parse_place;
 typedef enum {
     allDone,
     encodeError,
     keepGoing,
     needBytes
 } sec_asn1e_parse_status;
 typedef enum {
     hdr_normal      = 0,  /* encode header normally */
     hdr_any         = 1,  /* header already encoded in content */
     hdr_decoder     = 2,  /* template only used by decoder. skip it. */
     hdr_optional    = 3,  /* optional component, to be omitted */
     hdr_placeholder = 4   /* place holder for from_buf content */
 } sec_asn1e_hdr_encoding;
 typedef struct sec_asn1e_state_struct {
     SEC_ASN1EncoderContext *top;
     const SEC_ASN1Template *theTemplate;
     void *src;
     struct sec_asn1e_state_struct *parent;	/* aka prev */
     struct sec_asn1e_state_struct *child;	/* aka next */
     sec_asn1e_parse_place place;	/* where we are in encoding process */
     /*
      * XXX explain the next fields as clearly as possible...
      */
     unsigned char tag_modifiers;
     unsigned char tag_number;
     unsigned long underlying_kind;
     int depth;
     PRBool isExplicit,		/* we are handling an isExplicit header */
 	   indefinite,		/* need end-of-contents */
 	   is_string,		/* encoding a simple string or an ANY */
 	   may_stream,		/* when streaming, do indefinite encoding */
 	   optional,		/* omit field if it has no contents */
 	   disallowStreaming;	/* disallow streaming in all sub-templates */
 } sec_asn1e_state;
 /*
  * An "outsider" will have an opaque pointer to this, created by calling
  * SEC_ASN1EncoderStart().  It will be passed back in to all subsequent
  * calls to SEC_ASN1EncoderUpdate() and related routines, and when done
  * it is passed to SEC_ASN1EncoderFinish().
  */
 struct sec_EncoderContext_struct {
     PLArenaPool *our_pool;		/* for our internal allocs */
     sec_asn1e_state *current;
     sec_asn1e_parse_status status;
     PRBool streaming;
     PRBool from_buf;
     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 output_proc;	/* pass encoded bytes to this  */
     void *output_arg;			/* argument to that function */
 };
 static sec_asn1e_state *
 sec_asn1e_push_state (SEC_ASN1EncoderContext *cx,
 		      const SEC_ASN1Template *theTemplate,
 		      const void *src, PRBool new_depth)
 {
     sec_asn1e_state *state, *new_state;
     state = cx->current;
     new_state = (sec_asn1e_state*)PORT_ArenaZAlloc (cx->our_pool,
 						    sizeof(*new_state));
     if (new_state == NULL) {
 	cx->status = encodeError;
 	return NULL;
     }
     new_state->top = cx;
     new_state->parent = state;
     new_state->theTemplate = theTemplate;
     new_state->place = notInUse;
     if (src != NULL)
 	new_state->src = (char *)src + theTemplate->offset;
     if (state != NULL) {
 	new_state->depth = state->depth;
 	if (new_depth)
 	    new_state->depth++;
 	state->child = new_state;
     }
     cx->current = new_state;
     return new_state;
 }
 static void
 sec_asn1e_scrub_state (sec_asn1e_state *state)
 {
     /*
      * Some default "scrubbing".
      * XXX right set of initializations?
      */
     state->place = beforeHeader;
     state->indefinite = PR_FALSE;
 }
 static void
 sec_asn1e_notify_before (SEC_ASN1EncoderContext *cx, void *src, int depth)
 {
     if (cx->notify_proc == NULL)
 	return;
     cx->during_notify = PR_TRUE;
     (* cx->notify_proc) (cx->notify_arg, PR_TRUE, src, depth);
     cx->during_notify = PR_FALSE;
 }
 static void
 sec_asn1e_notify_after (SEC_ASN1EncoderContext *cx, void *src, int depth)
 {
     if (cx->notify_proc == NULL)
 	return;
     cx->during_notify = PR_TRUE;
     (* cx->notify_proc) (cx->notify_arg, PR_FALSE, src, depth);
     cx->during_notify = PR_FALSE;
 }
 static sec_asn1e_state *
 sec_asn1e_init_state_based_on_template (sec_asn1e_state *state)
 {
     PRBool isExplicit, is_string, may_stream, optional, universal;
     PRBool disallowStreaming;
     unsigned char tag_modifiers;
     unsigned long encode_kind, under_kind;
     unsigned long tag_number;
     PRBool isInline = PR_FALSE;
     encode_kind = state->theTemplate->kind;
     universal = ((encode_kind & SEC_ASN1_CLASS_MASK) == SEC_ASN1_UNIVERSAL)
 		? PR_TRUE : PR_FALSE;
     isExplicit = (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 (!(isExplicit && universal));	/* bad templates */
     may_stream = (encode_kind & SEC_ASN1_MAY_STREAM) ? PR_TRUE : PR_FALSE;
     encode_kind &= ~SEC_ASN1_MAY_STREAM;
     disallowStreaming = (encode_kind & SEC_ASN1_NO_STREAM) ? PR_TRUE : PR_FALSE;
     encode_kind &= ~SEC_ASN1_NO_STREAM;
     /* Just clear this to get it out of the way; we do not need it here */
     encode_kind &= ~SEC_ASN1_DYNAMIC;
     if( encode_kind & SEC_ASN1_CHOICE ) {
       under_kind = SEC_ASN1_CHOICE;
     } else if ((encode_kind & (SEC_ASN1_POINTER | SEC_ASN1_INLINE)) ||
         (!universal && !isExplicit)) {
 	const SEC_ASN1Template *subt;
 	void *src = NULL;
 	PORT_Assert ((encode_kind & (SEC_ASN1_ANY | SEC_ASN1_SKIP)) == 0);
 	sec_asn1e_scrub_state (state);
 	if (encode_kind & SEC_ASN1_POINTER) {
 	    src = *(void **)state->src;
 	    state->place = afterPointer;
 	    if (src == NULL) {
 		/*
 		 * If this is optional, but NULL, then the field does
 		 * not need to be encoded.  In this case we are done;
 		 * we do not want to push a subtemplate.
 		 */
 		if (optional)
 		    return state;
 		/*
 		 * XXX this is an error; need to figure out
 		 * how to handle this
 		 */
 	    }
 	} else {
 	    src = state->src;
 	    if (encode_kind & SEC_ASN1_INLINE) {
 		/* check that there are no extraneous bits */
 		/* PORT_Assert (encode_kind == SEC_ASN1_INLINE && !optional); */
 		state->place = afterInline;
 		isInline = PR_TRUE;
 	    } else {
 		/*
 		 * Save the tag modifiers and tag number here before moving
 		 * on to the next state in case this is a member of a
 		 * SEQUENCE OF
 		 */
 		state->tag_modifiers = (unsigned char)
 		    (encode_kind & (SEC_ASN1_TAG_MASK & ~SEC_ASN1_TAGNUM_MASK));
 		state->tag_number = (unsigned char)
 		    (encode_kind & SEC_ASN1_TAGNUM_MASK);
 		state->place = afterImplicit;
 		state->optional = optional;
 	    }
 	}
 	subt = SEC_ASN1GetSubtemplate (state->theTemplate, state->src, PR_TRUE);
 	if (isInline && optional) {
 	    /* we only handle a very limited set of optional inline cases at
 	       this time */
 	    if (PR_FALSE != SEC_ASN1IsTemplateSimple(subt)) {
 		/* we now know that the target is a SECItem*, so we can check
 		   if the source contains one */
 		SECItem* target = (SECItem*)state->src;
 		if (!target || !target->data || !target->len) {
 		    /* no valid data to encode subtemplate */
 		    return state;
 		}
 	    } else {
 		PORT_Assert(0); /* complex templates are not handled as
 				   inline optional */
 	    }
 	}
 	state = sec_asn1e_push_state (state->top, subt, src, PR_FALSE);
 	if (state == NULL)
 	    return state;
 	if (universal) {
 	    /*
 	     * This is a POINTER or INLINE; just init based on that
 	     * and we are done.
 	     */
 	    return sec_asn1e_init_state_based_on_template (state);
 	}
 	/*
 	 * This is an implicit, non-universal (meaning, application-private
 	 * or context-specific) field.  This results in a "magic" tag but
 	 * encoding based on the underlying type.  We pushed a new state
 	 * that is based on the subtemplate (the underlying type), but
 	 * now we will sort of alias it to give it some of our properties
 	 * (tag, optional status, etc.).
 	 *
 	 * NB: ALL the following flags in the subtemplate are disallowed
 	 *     and/or ignored: EXPLICIT, OPTIONAL, INNER, INLINE, POINTER.
 	 */
 	under_kind = state->theTemplate->kind;
 	if ((under_kind & SEC_ASN1_MAY_STREAM) && !disallowStreaming) {
 	    may_stream = PR_TRUE;
 	}
 	under_kind &= ~(SEC_ASN1_MAY_STREAM | SEC_ASN1_DYNAMIC);
     } else {
 	under_kind = encode_kind;
     }
     /*
      * Sanity check that there are no unwanted bits marked in under_kind.
      * These bits were either removed above (after we recorded them) or
      * they simply should not be found (signalling a bad/broken template).
      * XXX is this the right set of bits to test here? (i.e. need to add
      * or remove any?)
      */
 #define UNEXPECTED_FLAGS \
  (SEC_ASN1_EXPLICIT | SEC_ASN1_OPTIONAL | SEC_ASN1_SKIP | SEC_ASN1_INNER | \
   SEC_ASN1_DYNAMIC | SEC_ASN1_MAY_STREAM | SEC_ASN1_INLINE | SEC_ASN1_POINTER)
     PORT_Assert ((under_kind & UNEXPECTED_FLAGS) == 0);
     under_kind &= ~UNEXPECTED_FLAGS;
 #undef UNEXPECTED_FLAGS
     if (encode_kind & SEC_ASN1_ANY) {
 	PORT_Assert (encode_kind == under_kind);
 	tag_modifiers = 0;
 	tag_number = 0;
 	is_string = PR_TRUE;
     } else {
 	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.
 	 */
 	tag_number = encode_kind & SEC_ASN1_TAGNUM_MASK;
 	is_string = PR_FALSE;
 	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:
 	    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:
 	    /*
 	     * We do not yet know if we will be constructing the string,
 	     * so we have to wait to do this final tag modification.
 	     */
 	    is_string = PR_TRUE;
 	    break;
 	}
     }
     state->tag_modifiers = tag_modifiers;
     state->tag_number = (unsigned char)tag_number;
     state->underlying_kind = under_kind;
     state->isExplicit = isExplicit;
     state->may_stream = may_stream;
     state->is_string = is_string;
     state->optional = optional;
     state->disallowStreaming = disallowStreaming;
     sec_asn1e_scrub_state (state);
     return state;
 }
 static void
 sec_asn1e_write_part (sec_asn1e_state *state,
 		      const char *buf, unsigned long len,
 		      SEC_ASN1EncodingPart part)
 {
     SEC_ASN1EncoderContext *cx;
     cx = state->top;
     (* cx->output_proc) (cx->output_arg, buf, len, state->depth, part);
 }
 /*
  * XXX This assumes only single-octet identifiers.  To handle
  * the HIGH TAG form we would need to modify this interface and
  * teach it to properly encode the special form.
  */
 static void
 sec_asn1e_write_identifier_bytes (sec_asn1e_state *state, unsigned char value)
 {
     char byte;
     byte = (char) value;
     sec_asn1e_write_part (state, &byte, 1, SEC_ASN1_Identifier);
 }
 int
 SEC_ASN1EncodeLength(unsigned char *buf,int value) {
     int lenlen;
     lenlen = SEC_ASN1LengthLength (value);
     if (lenlen == 1) {
 	buf[0] = value;
     } else {
 	int i;
 	i = lenlen - 1;
 	buf[0] = 0x80 | i;
 	while (i) {
 	    buf[i--] = value;
 	    value >>= 8;
 	}
         PORT_Assert (value == 0);
     }
     return lenlen;
 }
 static void
 sec_asn1e_write_length_bytes (sec_asn1e_state *state, unsigned long value,
 			      PRBool indefinite)
 {
     int lenlen;
     unsigned char buf[sizeof(unsigned long) + 1];
     if (indefinite) {
 	PORT_Assert (value == 0);
 	buf[0] = 0x80;
 	lenlen = 1;
     } else {
 	lenlen = SEC_ASN1EncodeLength(buf,value);
     }
     sec_asn1e_write_part (state, (char *) buf, lenlen, SEC_ASN1_Length);
 }
 static void
 sec_asn1e_write_contents_bytes (sec_asn1e_state *state,
 				const char *buf, unsigned long len)
 {
     sec_asn1e_write_part (state, buf, len, SEC_ASN1_Contents);
 }
 static void
 sec_asn1e_write_end_of_contents_bytes (sec_asn1e_state *state)
 {
     const char eoc[2] = {0, 0};
     sec_asn1e_write_part (state, eoc, 2, SEC_ASN1_EndOfContents);
 }
 static int
 sec_asn1e_which_choice
 (
   void *src,
   const SEC_ASN1Template *theTemplate
 )
 {
   int rv;
   unsigned int which = *(unsigned int *)src;
   for( rv = 1, theTemplate++; theTemplate->kind != 0; rv++, theTemplate++ ) {
     if( which == theTemplate->size ) {
       return rv;
     }
   }
   return 0;
 }
 static unsigned long
 sec_asn1e_contents_length (const SEC_ASN1Template *theTemplate, void *src,
 			   PRBool disallowStreaming, PRBool insideIndefinite,
 			   sec_asn1e_hdr_encoding *pHdrException)
 {
     unsigned long encode_kind, underlying_kind;
     PRBool isExplicit, optional, universal, may_stream;
     unsigned long len;
     /*
      * This function currently calculates the length in all cases
      * except the following: when writing out the contents of a
      * template that belongs to a state where it was a sub-template
      * with the SEC_ASN1_MAY_STREAM bit set and it's parent had the
      * optional bit set.  The information that the parent is optional
      * and that we should return the length of 0 when that length is
      * present since that means the optional field is no longer present.
      * So we add the disallowStreaming flag which is passed in when
      * writing the contents, but for all recursive calls to
      * sec_asn1e_contents_length, we pass PR_FALSE, because this
      * function correctly calculates the length for children templates
      * from that point on.  Confused yet?  At least you didn't have
      * to figure it out.  ;)  -javi
      */
     encode_kind = theTemplate->kind;
     universal = ((encode_kind & SEC_ASN1_CLASS_MASK) == SEC_ASN1_UNIVERSAL)
 		? PR_TRUE : PR_FALSE;
     isExplicit = (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 (!(isExplicit && universal));	/* bad templates */
     may_stream = (encode_kind & SEC_ASN1_MAY_STREAM) ? PR_TRUE : PR_FALSE;
     encode_kind &= ~SEC_ASN1_MAY_STREAM;
     /* Just clear this to get it out of the way; we do not need it here */
     encode_kind &= ~SEC_ASN1_DYNAMIC;
     if (encode_kind & SEC_ASN1_NO_STREAM) {
 	disallowStreaming = PR_TRUE;
     }
     encode_kind &= ~SEC_ASN1_NO_STREAM;
     if (encode_kind & SEC_ASN1_CHOICE) {
 	void *src2;
 	int indx = sec_asn1e_which_choice(src, theTemplate);
 	if (0 == indx) {
 	    /* XXX set an error? "choice not found" */
 	    /* state->top->status = encodeError; */
 	    return 0;
 	}
         src2 = (void *)
 	        ((char *)src - theTemplate->offset + theTemplate[indx].offset);
         return sec_asn1e_contents_length(&theTemplate[indx], src2,
 					 disallowStreaming, insideIndefinite,
 					 pHdrException);
     }
     if ((encode_kind & (SEC_ASN1_POINTER | SEC_ASN1_INLINE)) || !universal) {
 	/* XXX any bits we want to disallow (PORT_Assert against) here? */
 	theTemplate = SEC_ASN1GetSubtemplate (theTemplate, src, PR_TRUE);
 	if (encode_kind & SEC_ASN1_POINTER) {
 	    src = *(void **)src;
 	    if (src == NULL) {
 		*pHdrException = optional ? hdr_optional : hdr_normal;
 		return 0;
 	    }
 	} else if (encode_kind & SEC_ASN1_INLINE) {
 	    /* check that there are no extraneous bits */
 	    if (optional) {
 		if (PR_FALSE != SEC_ASN1IsTemplateSimple(theTemplate)) {
 		    /* we now know that the target is a SECItem*, so we can check
 		       if the source contains one */
 		    SECItem* target = (SECItem*)src;
 		    if (!target || !target->data || !target->len) {
 			/* no valid data to encode subtemplate */
 			*pHdrException = hdr_optional;
 			return 0;
 		    }
 		} else {
 		    PORT_Assert(0); /* complex templates not handled as inline
                                        optional */
 		}
 	    }
 	}
 	src = (char *)src + theTemplate->offset;
 	/* recurse to find the length of the subtemplate */
 	len = sec_asn1e_contents_length (theTemplate, src, disallowStreaming,
 	                                 insideIndefinite, pHdrException);
 	if (len == 0 && optional) {
 	    *pHdrException = hdr_optional;
 	} else if (isExplicit) {
 	    if (*pHdrException == hdr_any) {
 		/* *we* do not want to add in a header,
 		** but our caller still does.
 		*/
 		*pHdrException = hdr_normal;
 	    } else if (*pHdrException == hdr_normal) {
 		/* if the inner content exists, our length is
 		 * len(identifier) + len(length) + len(innercontent)
 		 * XXX we currently assume len(identifier) == 1;
 		 * to support a high-tag-number this would need to be smarter.
 		 */
 		len += 1 + SEC_ASN1LengthLength (len);
 	    }
 	}
 	return len;
     }
     underlying_kind = encode_kind;
     /* This is only used in decoding; it plays no part in encoding.  */
     if (underlying_kind & SEC_ASN1_SAVE) {
 	/* check that there are no extraneous bits */
 	PORT_Assert (underlying_kind == SEC_ASN1_SAVE);
 	*pHdrException = hdr_decoder;
 	return 0;
     }
 #define UNEXPECTED_FLAGS \
  (SEC_ASN1_EXPLICIT | SEC_ASN1_OPTIONAL | SEC_ASN1_INLINE | SEC_ASN1_POINTER |\
   SEC_ASN1_DYNAMIC | SEC_ASN1_MAY_STREAM | SEC_ASN1_SAVE | SEC_ASN1_SKIP)
     /* Having any of these bits is not expected here...  */
     PORT_Assert ((underlying_kind & UNEXPECTED_FLAGS) == 0);
     underlying_kind &= ~UNEXPECTED_FLAGS;
 #undef UNEXPECTED_FLAGS
     if (underlying_kind & SEC_ASN1_CHOICE) {
 	void *src2;
 	int indx = sec_asn1e_which_choice(src, theTemplate);
 	if (0 == indx) {
 	    /* XXX set an error? "choice not found" */
 	    /* state->top->status = encodeError; */
 	    return 0;
 	}
         src2 = (void *)
 		((char *)src - theTemplate->offset + theTemplate[indx].offset);
         len = sec_asn1e_contents_length(&theTemplate[indx], src2,
 	                                disallowStreaming, insideIndefinite,
 					pHdrException);
     } else {
       switch (underlying_kind) {
       case SEC_ASN1_SEQUENCE_OF:
       case SEC_ASN1_SET_OF:
 	{
 	    const SEC_ASN1Template *tmpt;
 	    void *sub_src;
 	    unsigned long sub_len;
 	    void **group;
 	    len = 0;
 	    group = *(void ***)src;
 	    if (group == NULL)
 		break;
 	    tmpt = SEC_ASN1GetSubtemplate (theTemplate, src, PR_TRUE);
 	    for (; *group != NULL; group++) {
 		sub_src = (char *)(*group) + tmpt->offset;
 		sub_len = sec_asn1e_contents_length (tmpt, sub_src,
 		                                     disallowStreaming,
 						     insideIndefinite,
                                                      pHdrException);
 		len += sub_len;
 		/*
 		 * XXX The 1 below is the presumed length of the identifier;
 		 * to support a high-tag-number this would need to be smarter.
 		 */
 		if (*pHdrException == hdr_normal)
 		    len += 1 + SEC_ASN1LengthLength (sub_len);
 	    }
 	}
 	break;
       case SEC_ASN1_SEQUENCE:
       case SEC_ASN1_SET:
 	{
 	    const SEC_ASN1Template *tmpt;
 	    void *sub_src;
 	    unsigned long sub_len;
 	    len = 0;
 	    for (tmpt = theTemplate + 1; tmpt->kind; tmpt++) {
 		sub_src = (char *)src + tmpt->offset;
 		sub_len = sec_asn1e_contents_length (tmpt, sub_src,
 		                                     disallowStreaming,
 						     insideIndefinite,
                                                      pHdrException);
 		len += sub_len;
 		/*
 		 * XXX The 1 below is the presumed length of the identifier;
 		 * to support a high-tag-number this would need to be smarter.
 		 */
 		if (*pHdrException == hdr_normal)
 		    len += 1 + SEC_ASN1LengthLength (sub_len);
 	    }
 	}
 	break;
       case SEC_ASN1_BIT_STRING:
 	/* convert bit length to byte */
 	len = (((SECItem *)src)->len + 7) >> 3;
 	/* bit string contents involve an extra octet */
 	if (len)
 	    len++;
 	break;
       case SEC_ASN1_INTEGER:
 	/* ASN.1 INTEGERs are signed.
 	 * If the source is an unsigned integer, the encoder will need
 	 * to handle the conversion here.
 	 */
 	{
 	    unsigned char *buf = ((SECItem *)src)->data;
 	    SECItemType integerType = ((SECItem *)src)->type;
 	    len = ((SECItem *)src)->len;
 	    while (len > 0) {
 		if (*buf != 0) {
 		    if (*buf & 0x80 && integerType == siUnsignedInteger) {
 			len++; /* leading zero needed to make number signed */
 		    }
 		    break; /* reached beginning of number */
 		}
 		if (len == 1) {
 		    break; /* the number 0 */
 		}
 		if (buf[1] & 0x80) {
 		    break; /* leading zero already present */
 		}
 		/* extraneous leading zero, keep going */
 		buf++;
 		len--;
 	    }
 	}
 	break;
       default:
 	len = ((SECItem *)src)->len;
 	break;
       }  /* end switch */
 #ifndef WHAT_PROBLEM_DOES_THIS_SOLVE
       /* if we're streaming, we may have a secitem w/len 0 as placeholder */
       if (!len && insideIndefinite && may_stream && !disallowStreaming) {
 	  len = 1;
       }
 #endif
     }    /* end else */
     if (len == 0 && optional)
 	*pHdrException = hdr_optional;
     else if (underlying_kind == SEC_ASN1_ANY)
 	*pHdrException = hdr_any;
     else
 	*pHdrException = hdr_normal;
     return len;
 }
 static void
 sec_asn1e_write_header (sec_asn1e_state *state)
 {
     unsigned long contents_length;
     unsigned char tag_number, tag_modifiers;
     sec_asn1e_hdr_encoding hdrException = hdr_normal;
     PRBool indefinite = PR_FALSE;
     PORT_Assert (state->place == beforeHeader);
     tag_number = state->tag_number;
     tag_modifiers = state->tag_modifiers;
     if (state->underlying_kind == SEC_ASN1_ANY) {
 	state->place = duringContents;
 	return;
     }
     if (state->underlying_kind & SEC_ASN1_CHOICE) {
 	int indx = sec_asn1e_which_choice(state->src, state->theTemplate);
 	if( 0 == indx ) {
 	    /* XXX set an error? "choice not found" */
 	    state->top->status = encodeError;
 	    return;
 	}
 	state->place = afterChoice;
 	state = sec_asn1e_push_state(state->top, &state->theTemplate[indx],
 			       (char *)state->src - state->theTemplate->offset,
 			       PR_TRUE);
 	if (state) {
 	    /*
 	     * Do the "before" field notification.
 	     */
 	    sec_asn1e_notify_before (state->top, state->src, state->depth);
 	    state = sec_asn1e_init_state_based_on_template (state);
 	}
 	return;
     }
     /* The !isString test below is apparently intended to ensure that all
     ** constructed types receive indefinite length encoding.
     */
    indefinite = (PRBool)
 	(state->top->streaming && state->may_stream &&
 	 (state->top->from_buf || !state->is_string));
     /*
      * If we are doing a definite-length encoding, first we have to
      * walk the data structure to calculate the entire contents length.
      * If we are doing an indefinite-length encoding, we still need to
      * know if the contents is:
      *    optional and to be omitted, or
      *    an ANY (header is pre-encoded), or
      *    a SAVE or some other kind of template used only by the decoder.
      * So, we call this function either way.
      */
     contents_length = sec_asn1e_contents_length (state->theTemplate,
 						 state->src,
                                                  state->disallowStreaming,
 						 indefinite,
                                                  &hdrException);
     /*
      * We might be told explicitly not to put out a header.
      * But it can also be the case, via a pushed subtemplate, that
      * sec_asn1e_contents_length could not know that this field is
      * really optional.  So check for that explicitly, too.
      */
     if (hdrException != hdr_normal ||
 	(contents_length == 0 && state->optional)) {
 	state->place = afterContents;
 	if (state->top->streaming &&
 	    state->may_stream &&
 	    state->top->from_buf) {
 	    /* we did not find an optional indefinite string, so we
 	     * don't encode it.  However, if TakeFromBuf is on, we stop
 	     * here anyway to give our caller a chance to intercept at the
 	     * same point where we would stop if the field were present.
 	     */
 	    state->top->status = needBytes;
 	}
 	return;
     }
     if (indefinite) {
 	/*
 	 * We need to put out an indefinite-length encoding.
 	 * The only universal types that can be constructed are SETs,
 	 * SEQUENCEs, and strings; so check that it is one of those,
 	 * or that it is not universal (e.g. context-specific).
 	 */
 	state->indefinite = PR_TRUE;
 	PORT_Assert ((tag_number == SEC_ASN1_SET)
 		     || (tag_number == SEC_ASN1_SEQUENCE)
 		     || ((tag_modifiers & SEC_ASN1_CLASS_MASK) != 0)
 		     || state->is_string);
 	tag_modifiers |= SEC_ASN1_CONSTRUCTED;
 	contents_length = 0;
     }
     sec_asn1e_write_identifier_bytes (state,
                                 (unsigned char)(tag_number | tag_modifiers));
     sec_asn1e_write_length_bytes (state, contents_length, state->indefinite);
     if (contents_length == 0 && !state->indefinite) {
 	/*
 	 * If no real contents to encode, then we are done with this field.
 	 */
 	state->place = afterContents;
 	return;
     }
     /*
      * An EXPLICIT is nothing but an outer header, which we have already
      * written.  Now we need to do the inner header and contents.
      */
     if (state->isExplicit) {
 	const SEC_ASN1Template *subt =
 	      SEC_ASN1GetSubtemplate(state->theTemplate, state->src, PR_TRUE);
 	state->place = afterContents;
 	state = sec_asn1e_push_state (state->top, subt, state->src, PR_TRUE);
 	if (state != NULL)
 	    state = sec_asn1e_init_state_based_on_template (state);
 	return;
     }
     switch (state->underlying_kind) {
       case SEC_ASN1_SET_OF:
       case SEC_ASN1_SEQUENCE_OF:
 	/*
 	 * We need to push a child to handle each member.
 	 */
 	{
 	    void **group;
 	    const SEC_ASN1Template *subt;
 	    group = *(void ***)state->src;
 	    if (group == NULL || *group == NULL) {
 		/*
 		 * Group is empty; we are done.
 		 */
 		state->place = afterContents;
 		return;
 	    }
 	    state->place = duringGroup;
 	    subt = SEC_ASN1GetSubtemplate (state->theTemplate, state->src,
 					   PR_TRUE);
 	    state = sec_asn1e_push_state (state->top, subt, *group, PR_TRUE);
 	    if (state != NULL)
 		state = sec_asn1e_init_state_based_on_template (state);
 	}
 	break;
       case SEC_ASN1_SEQUENCE:
       case SEC_ASN1_SET:
 	/*
 	 * We need to push a child to handle the individual fields.
 	 */
 	state->place = duringSequence;
 	state = sec_asn1e_push_state (state->top, state->theTemplate + 1,
 				      state->src, PR_TRUE);
 	if (state != NULL) {
 	    /*
 	     * Do the "before" field notification.
 	     */
 	    sec_asn1e_notify_before (state->top, state->src, state->depth);
 	    state = sec_asn1e_init_state_based_on_template (state);
 	}
 	break;
       default:
 	/*
 	 * I think we do not need to do anything else.
 	 * XXX Correct?
 	 */
 	state->place = duringContents;
 	break;
     }
 }
 static void
 sec_asn1e_write_contents_from_buf (sec_asn1e_state *state,
 			  const char *buf, unsigned long len)
 {
     PORT_Assert (state->place == duringContents);
     PORT_Assert (state->top->from_buf);
     PORT_Assert (state->may_stream && !state->disallowStreaming);
     /*
      * Probably they just turned on "take from buf", but have not
      * yet given us any bytes.  If there is nothing in the buffer
      * then we have nothing to do but return and wait.
      */
     if (buf == NULL || len == 0) {
 	state->top->status = needBytes;
 	return;
     }
     /*
      * We are streaming, reading from a passed-in buffer.
      * This means we are encoding a simple string or an ANY.
      * For the former, we need to put out a substring, with its
      * own identifier and length.  For an ANY, we just write it
      * out as is (our caller is required to ensure that it
      * is a properly encoded entity).
      */
     PORT_Assert (state->is_string);		/* includes ANY */
     if (state->underlying_kind != SEC_ASN1_ANY) {
 	unsigned char identifier;
 	/*
 	 * Create the identifier based on underlying_kind.  We cannot
 	 * use tag_number and tag_modifiers because this can be an
 	 * implicitly encoded field.  In that case, the underlying
 	 * substrings *are* encoded with their real tag.
 	 */
 	identifier = (unsigned char)
 	                    (state->underlying_kind & SEC_ASN1_TAG_MASK);
 	/*
 	 * The underlying kind should just be a simple string; there
 	 * should be no bits like CONTEXT_SPECIFIC or CONSTRUCTED set.
 	 */
 	PORT_Assert ((identifier & SEC_ASN1_TAGNUM_MASK) == identifier);
 	/*
 	 * Write out the tag and length for the substring.
 	 */
 	sec_asn1e_write_identifier_bytes (state, identifier);
 	if (state->underlying_kind == SEC_ASN1_BIT_STRING) {
 	    char byte;
 	    /*
 	     * Assume we have a length in bytes but we need to output
 	     * a proper bit string.  This interface only works for bit
 	     * strings that are full multiples of 8.  If support for
 	     * real, variable length bit strings is needed then the
 	     * caller will have to know to pass in a bit length instead
 	     * of a byte length and then this code will have to
 	     * perform the encoding necessary (length written is length
 	     * in bytes plus 1, and the first octet of string is the
 	     * number of bits remaining between the end of the bit
 	     * string and the next byte boundary).
 	     */
 	    sec_asn1e_write_length_bytes (state, len + 1, PR_FALSE);
 	    byte = 0;
 	    sec_asn1e_write_contents_bytes (state, &byte, 1);
 	} else {
 	    sec_asn1e_write_length_bytes (state, len, PR_FALSE);
 	}
     }
     sec_asn1e_write_contents_bytes (state, buf, len);
     state->top->status = needBytes;
 }
 static void
 sec_asn1e_write_contents (sec_asn1e_state *state)
 {
     unsigned long len = 0;
     PORT_Assert (state->place == duringContents);
     switch (state->underlying_kind) {
       case SEC_ASN1_SET:
       case SEC_ASN1_SEQUENCE:
 	PORT_Assert (0);
 	break;
       case SEC_ASN1_BIT_STRING:
 	{
 	    SECItem *item;
 	    char rem;
 	    item = (SECItem *)state->src;
 	    len = (item->len + 7) >> 3;
 	    rem = (unsigned char)((len << 3) - item->len); /* remaining bits */
 	    sec_asn1e_write_contents_bytes (state, &rem, 1);
 	    sec_asn1e_write_contents_bytes (state, (char *) item->data, len);
 	}
 	break;
       case SEC_ASN1_BMP_STRING:
 	/* The number of bytes must be divisable by 2 */
 	if ((((SECItem *)state->src)->len) % 2) {
 	    SEC_ASN1EncoderContext *cx;
 	    cx = state->top;
 	    cx->status = encodeError;
 	    break;
 	}
 	/* otherwise, fall through to write the content */
 	goto process_string;
       case SEC_ASN1_UNIVERSAL_STRING:
 	/* The number of bytes must be divisable by 4 */
 	if ((((SECItem *)state->src)->len) % 4) {
 	    SEC_ASN1EncoderContext *cx;
 	    cx = state->top;
 	    cx->status = encodeError;
 	    break;
 	}
 	/* otherwise, fall through to write the content */
 	goto process_string;
       case SEC_ASN1_INTEGER:
        /* ASN.1 INTEGERs are signed.  If the source is an unsigned
 	* integer, the encoder will need to handle the conversion here.
 	*/
 	{
 	    unsigned int blen;
 	    unsigned char *buf;
 	    SECItemType integerType;
 	    blen = ((SECItem *)state->src)->len;
 	    buf = ((SECItem *)state->src)->data;
 	    integerType = ((SECItem *)state->src)->type;
 	    while (blen > 0) {
 		if (*buf & 0x80 && integerType == siUnsignedInteger) {
 		    char zero = 0; /* write a leading 0 */
 		    sec_asn1e_write_contents_bytes(state, &zero, 1);
 		    /* and then the remaining buffer */
 		    sec_asn1e_write_contents_bytes(state,
 						   (char *)buf, blen);
 		    break;
 		}
 		/* Check three possibilities:
 		 * 1.  No leading zeros, msb of MSB is not 1;
 		 * 2.  The number is zero itself;
 		 * 3.  Encoding a signed integer with a leading zero,
 		 *     keep the zero so that the number is positive.
 		 */
 		if (*buf != 0 ||
 		     blen == 1 ||
 		     (buf[1] & 0x80 && integerType != siUnsignedInteger) )
 		{
 		    sec_asn1e_write_contents_bytes(state,
 						   (char *)buf, blen);
 		    break;
 		}
 		/* byte is 0, continue */
 		buf++;
 		blen--;
 	    }
 	}
 	/* done with this content */
 	break;
 process_string:
       default:
 	{
 	    SECItem *item;
 	    item = (SECItem *)state->src;
 	    sec_asn1e_write_contents_bytes (state, (char *) item->data,
 					    item->len);
 	}
 	break;
     }
     state->place = afterContents;
 }
 /*
  * We are doing a SET OF or SEQUENCE OF, and have just finished an item.
  */
 static void
 sec_asn1e_next_in_group (sec_asn1e_state *state)
 {
     sec_asn1e_state *child;
     void **group;
     void *member;
     PORT_Assert (state->place == duringGroup);
     PORT_Assert (state->child != NULL);
     child = state->child;
     group = *(void ***)state->src;
     /*
      * Find placement of current item.
      */
     member = (char *)(state->child->src) - child->theTemplate->offset;
     while (*group != member)
 	group++;
     /*
      * Move forward to next item.
      */
     group++;
     if (*group == NULL) {
 	/*
 	 * That was our last one; we are done now.
 	 */
 	child->place = notInUse;
 	state->place = afterContents;
 	return;
     }
     child->src = (char *)(*group) + child->theTemplate->offset;
     /*
      * Re-"push" child.
      */
     sec_asn1e_scrub_state (child);
     state->top->current = child;
 }
 /*
  * We are moving along through a sequence; move forward by one,
  * (detecting end-of-sequence when it happens).
  */
 static void
 sec_asn1e_next_in_sequence (sec_asn1e_state *state)
 {
     sec_asn1e_state *child;
     PORT_Assert (state->place == duringSequence);
     PORT_Assert (state->child != NULL);
     child = state->child;
     /*
      * Do the "after" field notification.
      */
     sec_asn1e_notify_after (state->top, child->src, child->depth);
     /*
      * Move forward.
      */
     child->theTemplate++;
     if (child->theTemplate->kind == 0) {
 	/*
 	 * We are done with this sequence.
 	 */
 	child->place = notInUse;
 	state->place = afterContents;
 	return;
     }
     /*
      * Reset state and push.
      */
     child->src = (char *)state->src + child->theTemplate->offset;
     /*
      * Do the "before" field notification.
      */
     sec_asn1e_notify_before (state->top, child->src, child->depth);
     state->top->current = child;
     (void) sec_asn1e_init_state_based_on_template (child);
 }
 static void
 sec_asn1e_after_contents (sec_asn1e_state *state)
 {
     PORT_Assert (state->place == afterContents);
     if (state->indefinite)
 	sec_asn1e_write_end_of_contents_bytes (state);
     /*
      * 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;
 }
 /*
  * This function is called whether or not we are streaming; if we
  * *are* streaming, our caller can also instruct us to take bytes
  * from the passed-in buffer (at buf, for length len, which is likely
  * bytes but could even mean bits if the current field is a bit string).
  * If we have been so instructed, we will gobble up bytes from there
  * (rather than from our src structure) and output them, and then
  * we will just return, expecting to be called again -- either with
  * more bytes or after our caller has instructed us that we are done
  * (for now) with the buffer.
  */
 SECStatus
 SEC_ASN1EncoderUpdate (SEC_ASN1EncoderContext *cx,
 		       const char *buf, unsigned long len)
 {
     sec_asn1e_state *state;
     if (cx->status == needBytes) {
 	cx->status = keepGoing;
     }
     while (cx->status == keepGoing) {
 	state = cx->current;
 	switch (state->place) {
 	  case beforeHeader:
 	    sec_asn1e_write_header (state);
 	    break;
 	  case duringContents:
 	    if (cx->from_buf)
 		sec_asn1e_write_contents_from_buf (state, buf, len);
 	    else
 		sec_asn1e_write_contents (state);
 	    break;
 	  case duringGroup:
 	    sec_asn1e_next_in_group (state);
 	    break;
 	  case duringSequence:
 	    sec_asn1e_next_in_sequence (state);
 	    break;
 	  case afterContents:
 	    sec_asn1e_after_contents (state);
 	    break;
 	  case afterImplicit:
 	  case afterInline:
 	  case afterPointer:
 	  case afterChoice:
 	    /*
 	     * These states are more documentation than anything.
 	     * They just need to force a pop.
 	     */
 	    PORT_Assert (!state->indefinite);
 	    state->place = afterContents;
 	    break;
 	  case notInUse:
 	  default:
 	    /* This is not an error, but rather a plain old BUG! */
 	    PORT_Assert (0);
 	    cx->status = encodeError;
 	    break;
 	}
 	if (cx->status == encodeError)
 	    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) {
 	    cx->status = allDone;
 	    break;
 	}
     }
     if (cx->status == encodeError) {
 	return SECFailure;
     }
     return SECSuccess;
 }
 void
 SEC_ASN1EncoderFinish (SEC_ASN1EncoderContext *cx)
 {
     /*
      * XXX anything else that needs to be finished?
      */
     PORT_FreeArena (cx->our_pool, PR_FALSE);
 }
 SEC_ASN1EncoderContext *
 SEC_ASN1EncoderStart (const void *src, const SEC_ASN1Template *theTemplate,
 		      SEC_ASN1WriteProc output_proc, void *output_arg)
 {
     PLArenaPool *our_pool;
     SEC_ASN1EncoderContext *cx;
     our_pool = PORT_NewArena (SEC_ASN1_DEFAULT_ARENA_SIZE);
     if (our_pool == NULL)
 	return NULL;
     cx = (SEC_ASN1EncoderContext*)PORT_ArenaZAlloc (our_pool, sizeof(*cx));
     if (cx == NULL) {
 	PORT_FreeArena (our_pool, PR_FALSE);
 	return NULL;
     }
     cx->our_pool = our_pool;
     cx->output_proc = output_proc;
     cx->output_arg = output_arg;
     cx->status = keepGoing;
     if (sec_asn1e_push_state(cx, theTemplate, src, PR_FALSE) == NULL
 	|| sec_asn1e_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;
 }
 /*
  * XXX Do we need a FilterProc, too?
  */
 void
 SEC_ASN1EncoderSetNotifyProc (SEC_ASN1EncoderContext *cx,
 			      SEC_ASN1NotifyProc fn, void *arg)
 {
     cx->notify_proc = fn;
     cx->notify_arg = arg;
 }
 void
 SEC_ASN1EncoderClearNotifyProc (SEC_ASN1EncoderContext *cx)
 {
     cx->notify_proc = NULL;
     cx->notify_arg = NULL;	/* not necessary; just being clean */
 }
 void
 SEC_ASN1EncoderAbort(SEC_ASN1EncoderContext *cx, int error)
 {
     PORT_Assert(cx);
     PORT_SetError(error);
     cx->status = encodeError;
 }
 void
 SEC_ASN1EncoderSetStreaming (SEC_ASN1EncoderContext *cx)
 {
     /* XXX is there a way to check that we are "between" fields here? */
     cx->streaming = PR_TRUE;
 }
 void
 SEC_ASN1EncoderClearStreaming (SEC_ASN1EncoderContext *cx)
 {
     /* XXX is there a way to check that we are "between" fields here? */
     cx->streaming = PR_FALSE;
 }
 void
 SEC_ASN1EncoderSetTakeFromBuf (SEC_ASN1EncoderContext *cx)
 {
     /*
      * XXX is there a way to check that we are "between" fields here?  this
      * needs to include a check for being in between groups of items in
      * a SET_OF or SEQUENCE_OF.
      */
     PORT_Assert (cx->streaming);
     cx->from_buf = PR_TRUE;
 }
 void
 SEC_ASN1EncoderClearTakeFromBuf (SEC_ASN1EncoderContext *cx)
 {
     /* we should actually be taking from buf *now* */
     PORT_Assert (cx->from_buf);
     if (! cx->from_buf)		/* if not, just do nothing */
 	return;
     cx->from_buf = PR_FALSE;
     if (cx->status == needBytes) {
 	cx->status = keepGoing;
 	cx->current->place = afterContents;
     }
 }
 SECStatus
 SEC_ASN1Encode (const void *src, const SEC_ASN1Template *theTemplate,
 		SEC_ASN1WriteProc output_proc, void *output_arg)
 {
     SEC_ASN1EncoderContext *ecx;
     SECStatus rv;
     ecx = SEC_ASN1EncoderStart (src, theTemplate, output_proc, output_arg);
     if (ecx == NULL)
 	return SECFailure;
     rv = SEC_ASN1EncoderUpdate (ecx, NULL, 0);
     SEC_ASN1EncoderFinish (ecx);
     return rv;
 }
 /*
  * XXX depth and data_kind are unused; is there a PC way to silence warnings?
  * (I mean "politically correct", not anything to do with intel/win platform)
  */
 static void
 sec_asn1e_encode_item_count (void *arg, const char *buf, unsigned long len,
 			     int depth, SEC_ASN1EncodingPart data_kind)
 {
     unsigned long *count;
     count = (unsigned long*)arg;
     PORT_Assert (count != NULL);
     *count += len;
 }
 /* XXX depth and data_kind are unused; is there a PC way to silence warnings? */
 static void
 sec_asn1e_encode_item_store (void *arg, const char *buf, unsigned long len,
 			     int depth, SEC_ASN1EncodingPart data_kind)
 {
     SECItem *dest;
     dest = (SECItem*)arg;
     PORT_Assert (dest != NULL);
     PORT_Memcpy (dest->data + dest->len, buf, len);
     dest->len += len;
 }
 /*
  * Allocate an entire SECItem, or just the data part of it, to hold
  * "len" bytes of stuff.  Allocate from the given pool, if specified,
  * otherwise just do a vanilla PORT_Alloc.
  *
  * XXX This seems like a reasonable general-purpose function (for SECITEM_)?
  */
 static SECItem *
 sec_asn1e_allocate_item (PLArenaPool *poolp, SECItem *dest, unsigned long len)
 {
     if (poolp != NULL) {
 	void *release;
 	release = PORT_ArenaMark (poolp);
 	if (dest == NULL)
 	    dest = (SECItem*)PORT_ArenaAlloc (poolp, sizeof(SECItem));
 	if (dest != NULL) {
 	    dest->data = (unsigned char*)PORT_ArenaAlloc (poolp, len);
 	    if (dest->data == NULL) {
 		dest = NULL;
 	    }
 	}
 	if (dest == NULL) {
 	    /* one or both allocations failed; release everything */
 	    PORT_ArenaRelease (poolp, release);
 	} else {
 	    /* everything okay; unmark the arena */
 	    PORT_ArenaUnmark (poolp, release);
 	}
     } else {
 	SECItem *indest;
 	indest = dest;
 	if (dest == NULL)
 	    dest = (SECItem*)PORT_Alloc (sizeof(SECItem));
 	if (dest != NULL) {
 	    dest->type = siBuffer;
 	    dest->data = (unsigned char*)PORT_Alloc (len);
 	    if (dest->data == NULL) {
 		if (indest == NULL)
 		    PORT_Free (dest);
 		dest = NULL;
 	    }
 	}
     }
     return dest;
 }
 SECItem *
 SEC_ASN1EncodeItem (PLArenaPool *poolp, SECItem *dest, const void *src,
 		    const SEC_ASN1Template *theTemplate)
 {
     unsigned long encoding_length;
     SECStatus rv;
     PORT_Assert (dest == NULL || dest->data == NULL);
     encoding_length = 0;
     rv = SEC_ASN1Encode (src, theTemplate,
 			 sec_asn1e_encode_item_count, &encoding_length);
     if (rv != SECSuccess)
 	return NULL;
     dest = sec_asn1e_allocate_item (poolp, dest, encoding_length);
     if (dest == NULL)
 	return NULL;
     /* XXX necessary?  This really just checks for a bug in the allocate fn */
     PORT_Assert (dest->data != NULL);
     if (dest->data == NULL)
 	return NULL;
     dest->len = 0;
     (void) SEC_ASN1Encode (src, theTemplate, sec_asn1e_encode_item_store, dest);
     PORT_Assert (encoding_length == dest->len);
     return dest;
 }
 static SECItem *
 sec_asn1e_integer(PLArenaPool *poolp, SECItem *dest, unsigned long value,
 		  PRBool is_unsigned)
 {
     unsigned long copy;
     unsigned char sign;
     int len = 0;
     /*
      * Determine the length of the encoded value (minimum of 1).
      */
     copy = value;
     do {
 	len++;
 	sign = (unsigned char)(copy & 0x80);
 	copy >>= 8;
     } while (copy);
     /*
      * If 'value' is non-negative, and the high bit of the last
      * byte we counted was set, we need to add one to the length so
      * we put a high-order zero byte in the encoding.
      */
     if (sign && (is_unsigned || (long)value >= 0))
 	len++;
     /*
      * Allocate the item (if necessary) and the data pointer within.
      */
     dest = sec_asn1e_allocate_item (poolp, dest, len);
     if (dest == NULL)
 	return NULL;
     /*
      * Store the value, byte by byte, in the item.
      */
     dest->len = len;
     while (len) {
 	dest->data[--len] = (unsigned char)value;
 	value >>= 8;
     }
     PORT_Assert (value == 0);
     return dest;
 }
 SECItem *
 SEC_ASN1EncodeInteger(PLArenaPool *poolp, SECItem *dest, long value)
 {
     return sec_asn1e_integer (poolp, dest, (unsigned long) value, PR_FALSE);
 }
 SECItem *
 SEC_ASN1EncodeUnsignedInteger(PLArenaPool *poolp,
 			      SECItem *dest, unsigned long value)
 {
     return sec_asn1e_integer (poolp, dest, value, PR_TRUE);
 }

The Tor Browser / annotate

security/nss/lib/util/secasn1e.c@6474c204b198 (annotated)

security/nss/lib/util/secasn1e.c