netscape-revival
security/lib/util/derdec.c
#include "secder.h"
extern int SEC_ERROR_BAD_DER;
extern int SEC_ERROR_NO_MEMORY;
static uint32
der_indefinite_length(unsigned char *buf, unsigned char *end)
{
uint32 len, ret, dataLen;
unsigned char tag, lenCode;
int dataLenLen;
len = 0;
while ( 1 ) {
if ((buf + 2) > end) {
return(0);
}
tag = *buf++;
lenCode = *buf++;
len += 2;
if ( ( tag == 0 ) && ( lenCode == 0 ) ) {
return(len);
}
if ( lenCode == 0x80 ) { /* indefinite length */
ret = der_indefinite_length(buf, end); /* recurse to find length */
if (ret == 0)
return 0;
len += ret;
buf += ret;
} else { /* definite length */
if (lenCode & 0x80) {
/* Length of data is in multibyte format */
dataLenLen = lenCode & 0x7f;
switch (dataLenLen) {
case 1:
dataLen = buf[0];
break;
case 2:
dataLen = (buf[0]<<8)|buf[1];
break;
case 3:
dataLen = ((unsigned long)buf[0]<<16)|(buf[1]<<8)|buf[2];
break;
case 4:
dataLen = ((unsigned long)buf[0]<<24)|
((unsigned long)buf[1]<<16)|(buf[2]<<8)|buf[3];
break;
default:
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
} else {
/* Length of data is in single byte */
dataLen = lenCode;
dataLenLen = 0;
}
/* skip this item */
buf = buf + dataLenLen + dataLen;
len = len + dataLenLen + dataLen;
}
}
}
/*
** Capture the next thing in the buffer.
** Returns the length of the header and the length of the contents.
*/
static SECStatus
der_capture(unsigned char *buf, unsigned char *end,
int *header_len_p, uint32 *contents_len_p)
{
unsigned char *bp;
unsigned char whole_tag;
uint32 contents_len;
int tag_number;
if ((buf + 2) > end) {
*header_len_p = 0;
*contents_len_p = 0;
if (buf == end)
return SECSuccess;
return SECFailure;
}
bp = buf;
/* Get tag and verify that it is ok. */
whole_tag = *bp++;
tag_number = whole_tag & DER_TAGNUM_MASK;
/*
* XXX This code does not (yet) handle the high-tag-number form!
*/
if (tag_number == DER_HIGH_TAG_NUMBER) {
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
if ((whole_tag & DER_CLASS_MASK) == DER_UNIVERSAL) {
/* Check that the universal tag number is one we implement. */
switch (tag_number) {
case DER_BOOLEAN:
case DER_INTEGER:
case DER_BIT_STRING:
case DER_OCTET_STRING:
case DER_NULL:
case DER_OBJECT_ID:
case DER_SEQUENCE:
case DER_SET:
case DER_PRINTABLE_STRING:
case DER_T61_STRING:
case DER_IA5_STRING:
case DER_VISIBLE_STRING:
case DER_UTC_TIME:
case 0: /* end-of-contents tag */
break;
default:
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
}
/*
* Get first byte of length code (might contain entire length, might not).
*/
contents_len = *bp++;
/*
* If the high bit is set, then the length is in multibyte format,
* or the thing has an indefinite-length.
*/
if (contents_len & 0x80) {
int bytes_of_encoded_len;
bytes_of_encoded_len = contents_len & 0x7f;
contents_len = 0;
switch (bytes_of_encoded_len) {
case 4:
contents_len |= *bp++;
contents_len <<= 8;
/* fallthru */
case 3:
contents_len |= *bp++;
contents_len <<= 8;
/* fallthru */
case 2:
contents_len |= *bp++;
contents_len <<= 8;
/* fallthru */
case 1:
contents_len |= *bp++;
break;
case 0:
contents_len = der_indefinite_length (bp, end);
if (contents_len)
break;
/* fallthru */
default:
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
}
if ((bp + contents_len) > end) {
/* Ran past end of buffer */
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
*header_len_p = bp - buf;
*contents_len_p = contents_len;
return SECSuccess;
}
static unsigned char *
der_decode(PRArenaPool *arena, void *dest, DERTemplate *dtemplate,
unsigned char *buf, int header_len, uint32 contents_len)
{
unsigned char *orig_buf, *end;
unsigned long encode_kind, under_kind;
PRBool explicit, optional, universal, check_tag;
SECItem *item;
SECStatus rv;
PRBool indefinite_length, explicit_indefinite_length;
encode_kind = dtemplate->kind;
explicit = (encode_kind & DER_EXPLICIT) ? PR_TRUE : PR_FALSE;
optional = (encode_kind & DER_OPTIONAL) ? PR_TRUE : PR_FALSE;
universal = ((encode_kind & DER_CLASS_MASK) == DER_UNIVERSAL)
? PR_TRUE : PR_FALSE;
PORT_Assert (!(explicit && universal)); /* bad templates */
if (header_len == 0) {
if (optional || (encode_kind & DER_ANY))
return buf;
PORT_SetError(SEC_ERROR_BAD_DER);
return NULL;
}
if (encode_kind & DER_POINTER) {
void *place, **placep;
int offset;
if (dtemplate->sub != NULL) {
dtemplate = dtemplate->sub;
under_kind = dtemplate->kind;
if (universal) {
encode_kind = under_kind;
}
place = PORT_ArenaZAlloc(arena, dtemplate->arg);
offset = dtemplate->offset;
} else {
if (universal) {
under_kind = encode_kind & ~DER_POINTER;
} else {
under_kind = dtemplate->arg;
}
place = PORT_ArenaZAlloc(arena, sizeof(SECItem));
offset = 0;
}
if (place == NULL) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
return NULL; /* Out of memory */
}
placep = (void **)dest;
*placep = place;
dest = (void *)((char *)place + offset);
} else if (encode_kind & DER_INLINE) {
PORT_Assert (dtemplate->sub != NULL);
dtemplate = dtemplate->sub;
under_kind = dtemplate->kind;
if (universal) {
encode_kind = under_kind;
}
dest = (void *)((char *)dest + dtemplate->offset);
} else if (universal) {
under_kind = encode_kind;
} else {
under_kind = dtemplate->arg;
}
orig_buf = buf;
end = buf + header_len + contents_len;
explicit_indefinite_length = PR_FALSE;
if (explicit) {
/*
* This tag is expected to match exactly.
* (The template has all of the bits specified.)
*/
if (*buf != (encode_kind & DER_TAG_MASK)) {
if (optional)
return buf;
PORT_SetError(SEC_ERROR_BAD_DER);
return NULL;
}
if ((header_len == 2) && (*(buf + 1) == 0x80))
explicit_indefinite_length = PR_TRUE;
buf += header_len;
rv = der_capture (buf, end, &header_len, &contents_len);
if (rv != SECSuccess)
return NULL;
if (header_len == 0) { /* XXX is this right? */
PORT_SetError(SEC_ERROR_BAD_DER);
return NULL;
}
optional = PR_FALSE; /* can no longer be optional */
encode_kind = under_kind;
}
check_tag = PR_TRUE;
if (encode_kind & (DER_DERPTR | DER_ANY | DER_FORCE | DER_SKIP)) {
PORT_Assert ((encode_kind & DER_ANY) || !optional);
encode_kind = encode_kind & (~DER_FORCE);
under_kind = under_kind & (~DER_FORCE);
check_tag = PR_FALSE;
}
if (check_tag) {
PRBool wrong;
unsigned char expect_tag, expect_num;
/*
* This tag is expected to match, but the simple types
* may or may not have the constructed bit set, so we
* have to have all this extra logic.
*/
wrong = PR_TRUE;
expect_tag = encode_kind & DER_TAG_MASK;
expect_num = expect_tag & DER_TAGNUM_MASK;
if (expect_num == DER_SET || expect_num == DER_SEQUENCE) {
if (*buf == (expect_tag | DER_CONSTRUCTED))
wrong = PR_FALSE;
} else {
if (*buf == expect_tag)
wrong = PR_FALSE;
else if (*buf == (expect_tag | DER_CONSTRUCTED))
wrong = PR_FALSE;
}
if (wrong) {
if (optional)
return buf;
PORT_SetError(SEC_ERROR_BAD_DER);
return NULL;
}
}
if (under_kind & DER_DERPTR) {
item = (SECItem *)dest;
if (under_kind & DER_OUTER) {
item->data = buf;
item->len = header_len + contents_len;
} else {
item->data = buf + header_len;
item->len = contents_len;
}
return orig_buf;
}
if (encode_kind & DER_ANY) {
contents_len += header_len;
header_len = 0;
}
if ((header_len == 2) && (*(buf + 1) == 0x80))
indefinite_length = PR_TRUE;
else
indefinite_length = PR_FALSE;
buf += header_len;
if (contents_len == 0)
return buf;
under_kind &= ~DER_OPTIONAL;
if (under_kind & DER_INDEFINITE) {
int count, thing_size;
unsigned char *sub_buf;
DERTemplate *tmpt;
void *things, **indp, ***placep;
under_kind &= ~DER_INDEFINITE;
/*
* Count items.
*/
count = 0;
sub_buf = buf;
while (sub_buf < end) {
if (indefinite_length && sub_buf[0] == 0 && sub_buf[1] == 0) {
break;
}
rv = der_capture (sub_buf, end, &header_len, &contents_len);
if (rv != SECSuccess)
return NULL;
count++;
sub_buf += header_len + contents_len;
}
/*
* Allocate an array of pointers to items; extra one is for a NULL.
*/
indp = PORT_ArenaZAlloc(arena, (count + 1) * sizeof(void *));
if (indp == NULL) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
return NULL;
}
/*
* Prepare.
*/
if (under_kind == DER_SET || under_kind == DER_SEQUENCE) {
tmpt = dtemplate->sub;
PORT_Assert (tmpt != NULL);
thing_size = tmpt->arg;
PORT_Assert (thing_size != 0);
} else {
tmpt = NULL;
thing_size = sizeof(SECItem);
}
/*
* Allocate the items themselves.
*/
things = PORT_ArenaZAlloc(arena, count * thing_size);
if (things == NULL) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
return NULL;
}
placep = (void ***)dest;
*placep = indp;
while (count) {
/* ignore return value because we already did whole thing above */
(void) der_capture (buf, end, &header_len, &contents_len);
if (tmpt != NULL) {
void *sub_thing;
sub_thing = (void *)((char *)things + tmpt->offset);
buf = der_decode (arena, sub_thing, tmpt,
buf, header_len, contents_len);
if (buf == NULL)
return NULL;
} else {
item = (SECItem *)things;
if (under_kind == DER_ANY) {
contents_len += header_len;
header_len = 0;
}
buf += header_len;
if (under_kind == DER_BIT_STRING) {
item->data = buf + 1;
item->len = ((contents_len - 1) << 3) - *buf;
} else {
item->data = buf;
item->len = contents_len;
}
buf += contents_len;
}
*indp++ = things;
things = (void *)((char *)things + thing_size);
count--;
}
*indp = NULL;
goto der_decode_done;
}
switch (under_kind) {
case DER_SEQUENCE:
case DER_SET:
{
DERTemplate *tmpt;
void *sub_dest;
for (tmpt = dtemplate + 1; tmpt->kind; tmpt++) {
sub_dest = (void *)((char *)dest + tmpt->offset);
rv = der_capture (buf, end, &header_len, &contents_len);
if (rv != SECSuccess)
return NULL;
buf = der_decode (arena, sub_dest, tmpt,
buf, header_len, contents_len);
if (buf == NULL)
return NULL;
}
}
break;
case DER_BIT_STRING:
item = (SECItem *)dest;
item->data = buf + 1;
item->len = ((contents_len - 1) << 3) - *buf;
buf += contents_len;
break;
case DER_SKIP:
buf += contents_len;
break;
default:
item = (SECItem *)dest;
item->data = buf;
item->len = contents_len;
buf += contents_len;
break;
}
der_decode_done:
if (indefinite_length && buf[0] == 0 && buf[1] == 0) {
buf += 2;
}
if (explicit_indefinite_length && buf[0] == 0 && buf[1] == 0) {
buf += 2;
}
return buf;
}
SECStatus
DER_Decode(PRArenaPool *arena, void *dest, DERTemplate *dtemplate, SECItem *src)
{
unsigned char *buf;
uint32 buf_len, contents_len;
int header_len;
SECStatus rv;
buf = src->data;
buf_len = src->len;
rv = der_capture (buf, buf + buf_len, &header_len, &contents_len);
if (rv != SECSuccess)
return rv;
dest = (void *)((char *)dest + dtemplate->offset);
buf = der_decode (arena, dest, dtemplate, buf, header_len, contents_len);
if (buf == NULL)
return SECFailure;
return SECSuccess;
}
SECStatus
DER_Lengths(SECItem *item, int *header_len_p, uint32 *contents_len_p)
{
return(der_capture(item->data, &item->data[item->len], header_len_p,
contents_len_p));
}