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ASN.1: Helper functions for building DER encoded data

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Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
This commit is contained in:
Jouni Malinen 2020-01-31 15:28:25 +02:00 committed by Jouni Malinen
parent ce1f477397
commit 31b5950d0b
2 changed files with 161 additions and 0 deletions
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150
src/tls/asn1.c
View File

@ -9,6 +9,7 @@
#include "includes.h"
#include "common.h"
#include "utils/wpabuf.h"
#include "asn1.h"
const struct asn1_oid asn1_sha1_oid = {
@ -429,3 +430,152 @@ int asn1_get_alg_id(const u8 *buf, size_t len, struct asn1_oid *oid,
return 0;
}
void asn1_put_integer(struct wpabuf *buf, int val)
{
u8 bin[4];
int zeros;
WPA_PUT_BE32(bin, val);
zeros = 0;
while (zeros < 3 && bin[zeros] == 0)
zeros++;
wpabuf_put_u8(buf, ASN1_TAG_INTEGER);
wpabuf_put_u8(buf, 4 - zeros);
wpabuf_put_data(buf, &bin[zeros], 4 - zeros);
}
static void asn1_put_len(struct wpabuf *buf, size_t len)
{
if (len <= 0x7f) {
wpabuf_put_u8(buf, len);
} else if (len <= 0xff) {
wpabuf_put_u8(buf, 0x80 | 1);
wpabuf_put_u8(buf, len);
} else if (len <= 0xffff) {
wpabuf_put_u8(buf, 0x80 | 2);
wpabuf_put_be16(buf, len);
} else if (len <= 0xffffff) {
wpabuf_put_u8(buf, 0x80 | 3);
wpabuf_put_be24(buf, len);
} else {
wpabuf_put_u8(buf, 0x80 | 4);
wpabuf_put_be32(buf, len);
}
}
void asn1_put_octet_string(struct wpabuf *buf, const struct wpabuf *val)
{
wpabuf_put_u8(buf, ASN1_TAG_OCTETSTRING);
asn1_put_len(buf, wpabuf_len(val));
wpabuf_put_buf(buf, val);
}
void asn1_put_oid(struct wpabuf *buf, const struct asn1_oid *oid)
{
u8 *len;
size_t i;
if (oid->len < 2)
return;
wpabuf_put_u8(buf, ASN1_TAG_OID);
len = wpabuf_put(buf, 1);
wpabuf_put_u8(buf, 40 * oid->oid[0] + oid->oid[1]);
for (i = 2; i < oid->len; i++) {
unsigned long val = oid->oid[i];
u8 bytes[8];
int idx = 0;
while (val) {
bytes[idx] = (idx ? 0x80 : 0x00) | (val & 0x7f);
idx++;
val >>= 7;
}
if (idx == 0) {
bytes[idx] = 0;
idx = 1;
}
while (idx > 0) {
idx--;
wpabuf_put_u8(buf, bytes[idx]);
}
}
*len = (u8 *) wpabuf_put(buf, 0) - len - 1;
}
void asn1_put_hdr(struct wpabuf *buf, u8 class, int constructed, u8 tag,
size_t len)
{
wpabuf_put_u8(buf, class << 6 | (constructed ? 0x20 : 0x00) | tag);
asn1_put_len(buf, len);
}
void asn1_put_sequence(struct wpabuf *buf, const struct wpabuf *payload)
{
asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 1, ASN1_TAG_SEQUENCE,
wpabuf_len(payload));
wpabuf_put_buf(buf, payload);
}
void asn1_put_set(struct wpabuf *buf, const struct wpabuf *payload)
{
asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 1, ASN1_TAG_SET,
wpabuf_len(payload));
wpabuf_put_buf(buf, payload);
}
void asn1_put_utf8string(struct wpabuf *buf, const char *val)
{
asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 0, ASN1_TAG_UTF8STRING,
os_strlen(val));
wpabuf_put_str(buf, val);
}
struct wpabuf * asn1_build_alg_id(const struct asn1_oid *oid,
const struct wpabuf *params)
{
struct wpabuf *buf;
size_t len;
/*
* AlgorithmIdentifier ::= SEQUENCE {
* algorithm OBJECT IDENTIFIER,
* parameters ANY DEFINED BY algorithm OPTIONAL}
*/
len = 100;
if (params)
len += wpabuf_len(params);
buf = wpabuf_alloc(len);
if (!buf)
return NULL;
asn1_put_oid(buf, oid);
if (params)
wpabuf_put_buf(buf, params);
return asn1_encaps(buf, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
}
struct wpabuf * asn1_encaps(struct wpabuf *buf, u8 class, u8 tag)
{
struct wpabuf *res;
if (!buf)
return NULL;
res = wpabuf_alloc(10 + wpabuf_len(buf));
if (res) {
asn1_put_hdr(res, class, 1, tag, wpabuf_len(buf));
wpabuf_put_buf(res, buf);
}
wpabuf_clear_free(buf);
return res;
}

11
src/tls/asn1.h
View File

@ -70,6 +70,17 @@ int asn1_get_sequence(const u8 *buf, size_t len, struct asn1_hdr *hdr,
const u8 **next);
int asn1_get_alg_id(const u8 *buf, size_t len, struct asn1_oid *oid,
const u8 **params, size_t *params_len, const u8 **next);
void asn1_put_integer(struct wpabuf *buf, int val);
void asn1_put_octet_string(struct wpabuf *buf, const struct wpabuf *val);
void asn1_put_oid(struct wpabuf *buf, const struct asn1_oid *oid);
void asn1_put_hdr(struct wpabuf *buf, u8 class, int constructed, u8 tag,
size_t len);
void asn1_put_sequence(struct wpabuf *buf, const struct wpabuf *payload);
void asn1_put_set(struct wpabuf *buf, const struct wpabuf *payload);
void asn1_put_utf8string(struct wpabuf *buf, const char *val);
struct wpabuf * asn1_build_alg_id(const struct asn1_oid *oid,
const struct wpabuf *params);
struct wpabuf * asn1_encaps(struct wpabuf *buf, u8 class, u8 tag);
extern const struct asn1_oid asn1_sha1_oid;
extern const struct asn1_oid asn1_sha256_oid;