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/*
* ASN.1 DER parsing
* Copyright (c) 2006, Jouni Malinen <j@w1.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Alternatively, this software may be distributed under the terms of BSD
* license.
*
* See README and COPYING for more details.
*/
#include "includes.h"
#include "common.h"
#ifdef CONFIG_INTERNAL_X509
#include "asn1.h"
int asn1_get_next(const u8 *buf, size_t len, struct asn1_hdr *hdr)
{
const u8 *pos, *end;
u8 tmp;
os_memset(hdr, 0, sizeof(*hdr));
pos = buf;
end = buf + len;
hdr->identifier = *pos++;
hdr->class = hdr->identifier >> 6;
hdr->constructed = !!(hdr->identifier & (1 << 5));
if ((hdr->identifier & 0x1f) == 0x1f) {
hdr->tag = 0;
do {
if (pos >= end) {
wpa_printf(MSG_DEBUG, "ASN.1: Identifier "
"underflow");
return -1;
}
tmp = *pos++;
wpa_printf(MSG_MSGDUMP, "ASN.1: Extended tag data: "
"0x%02x", tmp);
hdr->tag = (hdr->tag << 7) | (tmp & 0x7f);
} while (tmp & 0x80);
} else
hdr->tag = hdr->identifier & 0x1f;
tmp = *pos++;
if (tmp & 0x80) {
if (tmp == 0xff) {
wpa_printf(MSG_DEBUG, "ASN.1: Reserved length "
"value 0xff used");
return -1;
}
tmp &= 0x7f; /* number of subsequent octets */
hdr->length = 0;
if (tmp > 4) {
wpa_printf(MSG_DEBUG, "ASN.1: Too long length field");
return -1;
}
while (tmp--) {
if (pos >= end) {
wpa_printf(MSG_DEBUG, "ASN.1: Length "
"underflow");
return -1;
}
hdr->length = (hdr->length << 8) | *pos++;
}
} else {
/* Short form - length 0..127 in one octet */
hdr->length = tmp;
}
if (end < pos || hdr->length > (unsigned int) (end - pos)) {
wpa_printf(MSG_DEBUG, "ASN.1: Contents underflow");
return -1;
}
hdr->payload = pos;
return 0;
}
int asn1_get_oid(const u8 *buf, size_t len, struct asn1_oid *oid,
const u8 **next)
{
struct asn1_hdr hdr;
const u8 *pos, *end;
unsigned long val;
u8 tmp;
os_memset(oid, 0, sizeof(*oid));
if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0)
return -1;
if (hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_OID) {
wpa_printf(MSG_DEBUG, "ASN.1: Expected OID - found class %d "
"tag 0x%x", hdr.class, hdr.tag);
return -1;
}
pos = hdr.payload;
end = hdr.payload + hdr.length;
*next = end;
while (pos < end) {
val = 0;
do {
if (pos >= end)
return -1;
tmp = *pos++;
val = (val << 7) | (tmp & 0x7f);
} while (tmp & 0x80);
if (oid->len >= ASN1_MAX_OID_LEN) {
wpa_printf(MSG_DEBUG, "ASN.1: Too long OID value");
return -1;
}
if (oid->len == 0) {
/*
* The first octet encodes the first two object
* identifier components in (X*40) + Y formula.
* X = 0..2.
*/
oid->oid[0] = val / 40;
if (oid->oid[0] > 2)
oid->oid[0] = 2;
oid->oid[1] = val - oid->oid[0] * 40;
oid->len = 2;
} else
oid->oid[oid->len++] = val;
}
return 0;
}
void asn1_oid_to_str(struct asn1_oid *oid, char *buf, size_t len)
{
char *pos = buf;
size_t i;
int ret;
if (len == 0)
return;
buf[0] = '\0';
for (i = 0; i < oid->len; i++) {
ret = os_snprintf(pos, buf + len - pos,
"%s%lu",
i == 0 ? "" : ".", oid->oid[i]);
if (ret < 0 || ret >= buf + len - pos)
break;
pos += ret;
}
buf[len - 1] = '\0';
}
static u8 rotate_bits(u8 octet)
{
int i;
u8 res;
res = 0;
for (i = 0; i < 8; i++) {
res <<= 1;
if (octet & 1)
res |= 1;
octet >>= 1;
}
return res;
}
unsigned long asn1_bit_string_to_long(const u8 *buf, size_t len)
{
unsigned long val = 0;
const u8 *pos = buf;
/* BER requires that unused bits are zero, so we can ignore the number
* of unused bits */
pos++;
if (len >= 2)
val |= rotate_bits(*pos++);
if (len >= 3)
val |= ((unsigned long) rotate_bits(*pos++)) << 8;
if (len >= 4)
val |= ((unsigned long) rotate_bits(*pos++)) << 16;
if (len >= 5)
val |= ((unsigned long) rotate_bits(*pos++)) << 24;
if (len >= 6)
wpa_printf(MSG_DEBUG, "X509: %s - some bits ignored "
"(BIT STRING length %lu)",
__func__, (unsigned long) len);
return val;
}
#endif /* CONFIG_INTERNAL_X509 */
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