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authorMichael Brown2016-07-28 16:02:15 +0200
committerMichael Brown2016-07-28 16:02:15 +0200
commit296670a6481ab8b4090c3e53fa4b8dc9518e7c69 (patch)
tree0512604b5923d4d32729131b16fe4870c32d7f32
parent[crypto] Remove obsolete extern declaration for asn1_invalidate_cursor() (diff)
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[crypto] Allow for parsing of partial ASN.1 cursors
Allow code to create a partial ASN.1 cursor containing only the type and length bytes, so that asn1_start() may be used to determine the length of a large ASN.1 blob without first allocating memory to hold the entire blob. Signed-off-by: Michael Brown <mcb30@ipxe.org>
-rw-r--r--src/crypto/asn1.c13
-rw-r--r--src/include/ipxe/asn1.h2
2 files changed, 9 insertions, 6 deletions
diff --git a/src/crypto/asn1.c b/src/crypto/asn1.c
index 9c71ffe1..03eb18f7 100644
--- a/src/crypto/asn1.c
+++ b/src/crypto/asn1.c
@@ -86,6 +86,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
*
* @v cursor ASN.1 object cursor
* @v type Expected type, or ASN1_ANY
+ * @v extra Additional length not present within partial cursor
* @ret len Length of object body, or negative error
*
* The object cursor will be updated to point to the start of the
@@ -93,7 +94,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
* the length of the object body (i.e. the number of bytes until the
* following object tag, if any) is returned.
*/
-static int asn1_start ( struct asn1_cursor *cursor, unsigned int type ) {
+int asn1_start ( struct asn1_cursor *cursor, unsigned int type, size_t extra ) {
unsigned int len_len;
unsigned int len;
@@ -135,9 +136,9 @@ static int asn1_start ( struct asn1_cursor *cursor, unsigned int type ) {
cursor->data++;
cursor->len--;
}
- if ( cursor->len < len ) {
+ if ( ( cursor->len + extra ) < len ) {
DBGC ( cursor, "ASN1 %p bad length %d (max %zd)\n",
- cursor, len, cursor->len );
+ cursor, len, ( cursor->len + extra ) );
return -EINVAL_ASN1_LEN;
}
@@ -158,7 +159,7 @@ static int asn1_start ( struct asn1_cursor *cursor, unsigned int type ) {
int asn1_enter ( struct asn1_cursor *cursor, unsigned int type ) {
int len;
- len = asn1_start ( cursor, type );
+ len = asn1_start ( cursor, type, 0 );
if ( len < 0 ) {
asn1_invalidate_cursor ( cursor );
return len;
@@ -185,7 +186,7 @@ int asn1_enter ( struct asn1_cursor *cursor, unsigned int type ) {
int asn1_skip_if_exists ( struct asn1_cursor *cursor, unsigned int type ) {
int len;
- len = asn1_start ( cursor, type );
+ len = asn1_start ( cursor, type, 0 );
if ( len < 0 )
return len;
@@ -242,7 +243,7 @@ int asn1_shrink ( struct asn1_cursor *cursor, unsigned int type ) {
/* Find end of object */
memcpy ( &temp, cursor, sizeof ( temp ) );
- len = asn1_start ( &temp, type );
+ len = asn1_start ( &temp, type, 0 );
if ( len < 0 ) {
asn1_invalidate_cursor ( cursor );
return len;
diff --git a/src/include/ipxe/asn1.h b/src/include/ipxe/asn1.h
index 70dd3eae..b0a82c00 100644
--- a/src/include/ipxe/asn1.h
+++ b/src/include/ipxe/asn1.h
@@ -337,6 +337,8 @@ asn1_type ( const struct asn1_cursor *cursor ) {
return ( ( cursor->len >= sizeof ( *type ) ) ? *type : ASN1_END );
}
+extern int asn1_start ( struct asn1_cursor *cursor, unsigned int type,
+ size_t extra );
extern int asn1_enter ( struct asn1_cursor *cursor, unsigned int type );
extern int asn1_skip_if_exists ( struct asn1_cursor *cursor,
unsigned int type );