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/*
* src/lib/krb5/asn.1/asn1_get.c
*
* Copyright 1994 by the Massachusetts Institute of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
#include "asn1_get.h"
asn1_error_code asn1_get_tag(buf, class, construction, tagnum, retlen)
asn1buf * buf;
asn1_class * class;
asn1_construction * construction;
asn1_tagnum * tagnum;
int * retlen;
{
asn1_error_code retval;
if (buf == NULL || buf->base == NULL ||
buf->bound - buf->next + 1 <= 0) {
*tagnum = ASN1_TAGNUM_CEILING;
return 0;
}
/* Allow for the indefinite encoding */
if ( !*(buf->next) && !*(buf->next + 1)) {
buf->next += 2;
*tagnum = ASN1_TAGNUM_CEILING;
return 0;
}
retval = asn1_get_id(buf,class,construction,tagnum);
if(retval) return retval;
retval = asn1_get_length(buf,retlen);
if(retval) return retval;
return 0;
}
asn1_error_code asn1_get_sequence(buf, retlen)
asn1buf * buf;
int * retlen;
{
asn1_error_code retval;
asn1_class class;
asn1_construction construction;
asn1_tagnum tagnum;
retval = asn1_get_tag(buf,&class,&construction,&tagnum,retlen);
if(retval) return retval;
if(retval) return (krb5_error_code)retval;
if(class != UNIVERSAL || construction != CONSTRUCTED ||
tagnum != ASN1_SEQUENCE) return ASN1_BAD_ID;
return 0;
}
/****************************************************************/
/* Private Procedures */
asn1_error_code asn1_get_id(buf, class, construction, tagnum)
asn1buf * buf;
asn1_class * class;
asn1_construction * construction;
asn1_tagnum * tagnum;
{
asn1_error_code retval;
asn1_tagnum tn=0;
asn1_octet o;
#define ASN1_CLASS_MASK 0xC0
#define ASN1_CONSTRUCTION_MASK 0x20
#define ASN1_TAG_NUMBER_MASK 0x1F
retval = asn1buf_remove_octet(buf,&o);
if(retval) return retval;
if(class != NULL)
*class = (asn1_class)(o&ASN1_CLASS_MASK);
if(construction != NULL)
*construction = (asn1_construction)(o&ASN1_CONSTRUCTION_MASK);
if((o&ASN1_TAG_NUMBER_MASK) != ASN1_TAG_NUMBER_MASK){
/* low-tag-number form */
if(tagnum != NULL) *tagnum = (asn1_tagnum)(o&ASN1_TAG_NUMBER_MASK);
}else{
/* high-tag-number form */
do{
retval = asn1buf_remove_octet(buf,&o);
if(retval) return retval;
tn = (tn<<7) + (asn1_tagnum)(o&0x7F);
}while(tn&0x80);
if(tagnum != NULL) *tagnum = tn;
}
return 0;
}
asn1_error_code asn1_get_length(buf, retlen)
asn1buf * buf;
int * retlen;
{
asn1_error_code retval;
asn1_octet o;
retval = asn1buf_remove_octet(buf,&o);
if(retval) return retval;
if((o&0x80) == 0){
if(retlen != NULL) *retlen = (int)(o&0x7F);
}else{
int num;
int len=0;
for(num = (int)(o&0x7F); num>0; num--){
retval = asn1buf_remove_octet(buf,&o);
if(retval) return retval;
len = (len<<8) + (int)o;
}
if(retlen != NULL) *retlen = len;
}
return 0;
}
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