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/*-
* Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
* Redistribution and modifications are permitted subject to BSD license.
*/
#include <constr_TYPE.h>
#include <ber_tlv_length.h>
#include <ber_tlv_tag.h>
ssize_t
ber_fetch_length(int _is_constructed, void *bufptr, size_t size,
ber_tlv_len_t *len_r) {
uint8_t *buf = (uint8_t *)bufptr;
unsigned oct;
if(size == 0)
return 0; /* Want more */
oct = *(uint8_t *)buf;
if((oct & 0x80) == 0) {
/*
* Short definite length.
*/
*len_r = (oct & 0x7F);
return 1;
} else {
ber_tlv_len_t len;
size_t skipped;
if(_is_constructed && oct == 0x80) {
*len_r = -1; /* Indefinite length */
return 1;
}
if(oct == 0xff) {
/* Reserved in standard for future use. */
return -1;
}
oct &= 0x7F; /* Leave only the 7 LS bits */
for(len = 0, buf++, skipped = 1;
oct && (++skipped < size); buf++, oct--) {
len = (len << 8) | *buf;
if(len < 0
|| (len >> ((8 * sizeof(len)) - 8) && oct > 1)) {
/*
* Too large length value.
*/
return -1;
}
}
if(oct == 0) {
*len_r = len;
return skipped;
}
return 0; /* Want more */
}
}
ssize_t
ber_skip_length(int _is_constructed, void *ptr, size_t size) {
ber_tlv_len_t vlen; /* Length of V in TLV */
ssize_t tl; /* Length of L in TLV */
ssize_t ll; /* Length of L in TLV */
size_t skip;
/*
* Determine the size of L in TLV.
*/
ll = ber_fetch_length(_is_constructed, ptr, size, &vlen);
if(ll <= 0) return ll;
/*
* Definite length.
*/
if(vlen >= 0) {
skip = ll + vlen;
if(skip > size)
return 0; /* Want more */
return skip;
}
/*
* Indefinite length!
*/
ASN_DEBUG("Skipping indefinite length");
for(skip = ll, (char *)ptr += ll, size -= ll;;) {
ber_tlv_tag_t tag;
/* Fetch the tag */
tl = ber_fetch_tag(ptr, size, &tag);
if(tl <= 0) return tl;
ll = ber_skip_length(BER_TLV_CONSTRUCTED(ptr),
(char *)ptr + tl, size - tl);
if(ll <= 0) return ll;
skip += tl + ll;
/*
* This may be the end of the indefinite length structure,
* two consecutive 0 octets.
* Check if it is true.
*/
if(((uint8_t *)ptr)[0] == 0
&& ((uint8_t *)ptr)[1] == 0)
return skip;
(char *)ptr += tl + ll;
size -= tl + ll;
}
/* UNREACHABLE */
}
ssize_t
der_tlv_length_serialize(ber_tlv_len_t len, void *bufp, size_t size) {
size_t computed_size; /* Size of len encoding */
uint8_t *buf = (uint8_t *)bufp;
uint8_t *end;
int i;
if(len <= 127) {
/* Encoded in 1 octet */
if(size) *buf = len;
return 1;
}
/*
* Compute the size of the subsequent bytes.
*/
computed_size = sizeof(len); /* assert(sizeof(len)<128), n.p. */
for(i = (8*(sizeof(len)-1)); i > 0; i -= 8) {
if((len >> i) & 0xFF) break;
computed_size--;
}
if(size) {
*buf++ = 0x80 | computed_size; /* Length of the encoding */
size--;
}
/*
* Produce the len encoding, space permitting.
*/
if(size > computed_size)
end = buf + computed_size;
else
end = buf + size;
for((void)i /* Reuse bits count */; buf < end; i -= 8, buf++) {
*buf = (len >> i) & 0xFF;
}
return computed_size + 1;
}
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