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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_tag.h>
#include <errno.h>
ssize_t
ber_fetch_tag(void *ptr, size_t size, ber_tlv_tag_t *tag_r) {
ber_tlv_tag_t val;
ber_tlv_tag_t tclass;
ssize_t skipped;
if(size == 0)
return 0;
val = *(uint8_t *)ptr;
tclass = (val >> 6);
if((val &= 31) != 31) {
/*
* Simple form: everything encoded in a single octet.
* Tag Class is encoded using two least significant bits.
*/
*tag_r = (val << 2) | tclass;
return 1;
}
/*
* Each octet contains 7 bits of useful information.
* The MSB is 0 if it is the last octet of the tag.
*/
for(val = 0, ptr++, skipped = 2; skipped < size; ptr++, skipped++) {
unsigned oct = *(uint8_t *)ptr;
if(oct & 0x80) {
val = (val << 7) | (oct & 0x7F);
/*
* Make sure there are at least 9 bits spare
* at the MS side of a value.
*/
if(val >> ((8 * sizeof(val)) - 9)) {
/*
* We would not be able to accomodate
* any more tag bits.
*/
return -1;
}
} else {
*tag_r = (val << 9) | (oct << 2) | tclass;
return skipped;
}
}
return 0; /* Want more */
}
ssize_t
ber_tlv_tag_fwrite(ber_tlv_tag_t tag, FILE *f) {
char buf[sizeof("[APPLICATION ]") + 32];
ssize_t ret;
ret = ber_tlv_tag_snprint(tag, buf, sizeof(buf));
if(ret >= sizeof(buf) || ret < 2) {
errno = EPERM;
return -1;
}
return fwrite(buf, 1, ret, f);
}
ssize_t
ber_tlv_tag_snprint(ber_tlv_tag_t tag, char *buf, size_t size) {
char *type = 0;
int ret;
switch(tag & 0x3) {
case ASN_TAG_CLASS_UNIVERSAL: type = "UNIVERSAL "; break;
case ASN_TAG_CLASS_APPLICATION: type = "APPLICATION "; break;
case ASN_TAG_CLASS_CONTEXT: type = ""; break;
case ASN_TAG_CLASS_PRIVATE: type = "PRIVATE "; break;
}
ret = snprintf(buf, size, "[%s%u]", type, ((unsigned)tag) >> 2);
if(ret <= 0 && size) buf[0] = '\0'; /* against broken libc's */
return ret;
}
char *
ber_tlv_tag_string(ber_tlv_tag_t tag) {
static char buf[sizeof("[APPLICATION ]") + 32];
(void)ber_tlv_tag_snprint(tag, buf, sizeof(buf));
return buf;
}
ssize_t
der_tlv_tag_serialize(ber_tlv_tag_t tag, void *bufp, size_t size) {
int tclass = BER_TAG_CLASS(tag);
ber_tlv_tag_t tval = BER_TAG_VALUE(tag);
uint8_t *buf = bufp;
uint8_t *end;
ssize_t computed_size;
int i;
if(tval <= 30) {
/* Encoded in 1 octet */
if(size) buf[0] = (tclass << 6) | tval;
return 1;
} else if(size) {
*buf++ = (tclass << 6) | 0x1F;
size--;
}
/*
* Compute the size of the subsequent bytes.
* The routine is written so every floating-point
* operation is done at compile time.
* Note, there is a subtle problem lurking here,
* could you guess where it is? :)
* Hint: what happens when ((8*sizeof(tag))%7) == 0?
*/
computed_size = 1 + 8 * sizeof(tag) / 7;
for(i = (8*sizeof(tag)) - ((8*sizeof(tag))%7); i >= 7; i -= 7) {
if((tval >> i) & 0x7F) break;
computed_size--;
}
/*
* Fill in the buffer, space permitting.
*/
if(size > computed_size)
end = buf + computed_size;
else
end = buf + size;
for((void)i; buf < end; i -= 7, buf++) {
*buf = 0x80 | ((tval>>i) & 0x7F);
}
return computed_size + 1;
}
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