asn1_decode.c revision 159d09a20817016f09b3ea28d1bdada4a336bb91
/*
* src/lib/krb5/asn.1/asn1_decode.c
*
* Copyright 1994, 2003 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.
*/
/* ASN.1 primitive decoders */
#include "asn1_decode.h"
#include "asn1_get.h"
#include <stdio.h>
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#ifdef TIME_WITH_SYS_TIME
#include <time.h>
#endif
#else
#include <time.h>
#endif
#define setup()\
asn1_error_code retval;\
taginfo tinfo
#define asn1class (tinfo.asn1class)
#define construction (tinfo.construction)
#define tagnum (tinfo.tagnum)
#define length (tinfo.length)
#define tag(type)\
retval = asn1_get_tag_2(buf,&tinfo);\
if(retval) return retval;\
if(asn1class != UNIVERSAL || construction != PRIMITIVE || tagnum != type)\
return ASN1_BAD_ID
#define cleanup()\
return 0
extern time_t krb5int_gmt_mktime (struct tm *);
asn1_error_code asn1_decode_integer(asn1buf *buf, long int *val)
{
setup();
asn1_octet o;
long n = 0; /* initialize to keep gcc happy */
int i;
tag(ASN1_INTEGER);
for (i = 0; i < length; i++) {
retval = asn1buf_remove_octet(buf, &o);
if (retval) return retval;
if (!i) {
n = (0x80 & o) ? -1 : 0; /* grab sign bit */
if (n < 0 && length > sizeof (long))
return ASN1_OVERFLOW;
else if (length > sizeof (long) + 1) /* allow extra octet for positive */
return ASN1_OVERFLOW;
}
n = (n << 8) | o;
}
*val = n;
cleanup();
}
asn1_error_code asn1_decode_unsigned_integer(asn1buf *buf, long unsigned int *val)
{
setup();
asn1_octet o;
unsigned long n;
int i;
tag(ASN1_INTEGER);
for (i = 0, n = 0; i < length; i++) {
retval = asn1buf_remove_octet(buf, &o);
if(retval) return retval;
if (!i) {
if (0x80 & o)
return ASN1_OVERFLOW;
else if (length > sizeof (long) + 1)
return ASN1_OVERFLOW;
}
n = (n << 8) | o;
}
*val = n;
cleanup();
}
/*
* asn1_decode_maybe_unsigned
*
* This is needed because older releases of MIT krb5 have signed
* sequence numbers. We want to accept both signed and unsigned
* sequence numbers, in the range -2^31..2^32-1, mapping negative
* numbers into their positive equivalents in the same way that C's
* normal integer conversions do, i.e., would preserve bits on a
* two's-complement architecture.
*/
asn1_error_code asn1_decode_maybe_unsigned(asn1buf *buf, unsigned long *val)
{
setup();
asn1_octet o;
unsigned long n, bitsremain;
unsigned int i;
tag(ASN1_INTEGER);
o = 0;
n = 0;
bitsremain = ~0UL;
for (i = 0; i < length; i++) {
/* Accounts for u_long width not being a multiple of 8. */
if (bitsremain < 0xff) return ASN1_OVERFLOW;
retval = asn1buf_remove_octet(buf, &o);
if (retval) return retval;
if (bitsremain == ~0UL) {
if (i == 0)
n = (o & 0x80) ? ~0UL : 0UL; /* grab sign bit */
/*
* Skip leading zero or 0xFF octets to humor non-compliant encoders.
*/
if (n == 0 && o == 0)
continue;
if (n == ~0UL && o == 0xff)
continue;
}
n = (n << 8) | o;
bitsremain >>= 8;
}
*val = n;
cleanup();
}
asn1_error_code asn1_decode_oid(asn1buf *buf, unsigned int *retlen, asn1_octet **val)
{
setup();
tag(ASN1_OBJECTIDENTIFIER);
retval = asn1buf_remove_octetstring(buf, length, val);
if (retval) return retval;
*retlen = length;
cleanup();
}
asn1_error_code asn1_decode_octetstring(asn1buf *buf, unsigned int *retlen, asn1_octet **val)
{
setup();
tag(ASN1_OCTETSTRING);
retval = asn1buf_remove_octetstring(buf,length,val);
if(retval) return retval;
*retlen = length;
cleanup();
}
asn1_error_code asn1_decode_charstring(asn1buf *buf, unsigned int *retlen, char **val)
{
setup();
tag(ASN1_OCTETSTRING);
retval = asn1buf_remove_charstring(buf,length,val);
if(retval) return retval;
*retlen = length;
cleanup();
}
asn1_error_code asn1_decode_generalstring(asn1buf *buf, unsigned int *retlen, char **val)
{
setup();
tag(ASN1_GENERALSTRING);
retval = asn1buf_remove_charstring(buf,length,val);
if(retval) return retval;
*retlen = length;
cleanup();
}
asn1_error_code asn1_decode_null(asn1buf *buf)
{
setup();
tag(ASN1_NULL);
if(length != 0) return ASN1_BAD_LENGTH;
cleanup();
}
asn1_error_code asn1_decode_printablestring(asn1buf *buf, int *retlen, char **val)
{
setup();
tag(ASN1_PRINTABLESTRING);
retval = asn1buf_remove_charstring(buf,length,val);
if(retval) return retval;
*retlen = length;
cleanup();
}
asn1_error_code asn1_decode_ia5string(asn1buf *buf, int *retlen, char **val)
{
setup();
tag(ASN1_IA5STRING);
retval = asn1buf_remove_charstring(buf,length,val);
if(retval) return retval;
*retlen = length;
cleanup();
}
asn1_error_code asn1_decode_generaltime(asn1buf *buf, time_t *val)
{
setup();
char *s;
struct tm ts;
time_t t;
tag(ASN1_GENERALTIME);
if(length != 15) return ASN1_BAD_LENGTH;
retval = asn1buf_remove_charstring(buf,15,&s);
/* Time encoding: YYYYMMDDhhmmssZ */
if(s[14] != 'Z') {
free(s);
return ASN1_BAD_FORMAT;
}
if(s[0] == '1' && !memcmp("19700101000000Z", s, 15)) {
t = 0;
free(s);
goto done;
}
#define c2i(c) ((c)-'0')
ts.tm_year = 1000*c2i(s[0]) + 100*c2i(s[1]) + 10*c2i(s[2]) + c2i(s[3])
- 1900;
ts.tm_mon = 10*c2i(s[4]) + c2i(s[5]) - 1;
ts.tm_mday = 10*c2i(s[6]) + c2i(s[7]);
ts.tm_hour = 10*c2i(s[8]) + c2i(s[9]);
ts.tm_min = 10*c2i(s[10]) + c2i(s[11]);
ts.tm_sec = 10*c2i(s[12]) + c2i(s[13]);
ts.tm_isdst = -1;
t = krb5int_gmt_mktime(&ts);
free(s);
if(t == -1) return ASN1_BAD_TIMEFORMAT;
done:
*val = t;
cleanup();
}