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authorH. Peter Anvin <hpa@zytor.com>2008-03-26 16:25:35 -0700
committerH. Peter Anvin <hpa@zytor.com>2008-03-26 16:25:35 -0700
commit9eddd22a7b53b1d02fbae0d987df8af122924248 (patch)
tree882f5152880b0b1aa2d7a0619d30065acc69fb16 /gpxe/src/crypto/asn1.c
parentbbb8f15936b851e6a0ef6f7bb2c95197bff35994 (diff)
downloadsyslinux-9eddd22a7b53b1d02fbae0d987df8af122924248.tar.gz
Add gPXE into the source tree; build unified imagesyslinux-3.70-pre7
Diffstat (limited to 'gpxe/src/crypto/asn1.c')
-rw-r--r--gpxe/src/crypto/asn1.c159
1 files changed, 159 insertions, 0 deletions
diff --git a/gpxe/src/crypto/asn1.c b/gpxe/src/crypto/asn1.c
new file mode 100644
index 00000000..0a69162a
--- /dev/null
+++ b/gpxe/src/crypto/asn1.c
@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdint.h>
+#include <stddef.h>
+#include <errno.h>
+#include <gpxe/asn1.h>
+
+/** @file
+ *
+ * ASN.1 encoding
+ *
+ */
+
+/**
+ * Start parsing ASN.1 object
+ *
+ * @v cursor ASN.1 object cursor
+ * @v type Expected type
+ * @ret len Length of object body, or -1 on error
+ *
+ * The object cursor will be updated to point to the start of the
+ * object body (i.e. the first byte following the length byte(s)), and
+ * the length of the object body (i.e. the number of bytes until the
+ * following object tag, if any) is returned.
+ *
+ * If any error occurs (i.e. if the object is not of the expected
+ * type, or if we overflow beyond the end of the ASN.1 object), then
+ * the cursor will be invalidated and a negative value will be
+ * returned.
+ */
+static int asn1_start_object ( struct asn1_cursor *cursor,
+ unsigned int type ) {
+ unsigned int len_len;
+ unsigned int len;
+
+ /* Sanity check */
+ if ( cursor->len < 2 /* Tag byte and first length byte */ ) {
+ if ( cursor->len )
+ DBGC ( cursor, "ASN1 %p too short\n", cursor );
+ goto notfound;
+ }
+
+ /* Check the tag byte */
+ if ( cursor->data[0] != type ) {
+ DBGC ( cursor, "ASN1 %p type mismatch (expected %d, got %d)\n",
+ cursor, type, cursor->data[0] );
+ goto notfound;
+ }
+ cursor->data++;
+ cursor->len--;
+
+ /* Extract length of the length field and sanity check */
+ len_len = cursor->data[0];
+ if ( len_len & 0x80 ) {
+ len_len = ( len_len & 0x7f );
+ cursor->data++;
+ cursor->len--;
+ } else {
+ len_len = 1;
+ }
+ if ( cursor->len < len_len ) {
+ DBGC ( cursor, "ASN1 %p bad length field length %d (max "
+ "%zd)\n", cursor, len_len, cursor->len );
+ goto notfound;
+ }
+
+ /* Extract the length and sanity check */
+ for ( len = 0 ; len_len ; len_len-- ) {
+ len <<= 8;
+ len |= cursor->data[0];
+ cursor->data++;
+ cursor->len--;
+ }
+ if ( cursor->len < len ) {
+ DBGC ( cursor, "ASN1 %p bad length %d (max %zd)\n",
+ cursor, len, cursor->len );
+ goto notfound;
+ }
+
+ return len;
+
+ notfound:
+ cursor->data = NULL;
+ cursor->len = 0;
+ return -1;
+}
+
+/**
+ * Enter ASN.1 object
+ *
+ * @v cursor ASN.1 object cursor
+ * @v type Expected type
+ * @ret rc Return status code
+ *
+ * The object cursor will be updated to point to the body of the
+ * current ASN.1 object. If any error occurs, the object cursor will
+ * be invalidated.
+ */
+int asn1_enter_object ( struct asn1_cursor *cursor, unsigned int type ) {
+ int len;
+
+ len = asn1_start_object ( cursor, type );
+ if ( len < 0 )
+ return -ENOENT;
+
+ cursor->len = len;
+ DBGC ( cursor, "ASN1 %p entered object type %02x (len %x)\n",
+ cursor, type, len );
+
+ return 0;
+}
+
+/**
+ * Skip ASN.1 object
+ *
+ * @v cursor ASN.1 object cursor
+ * @v type Expected type
+ * @ret rc Return status code
+ *
+ * The object cursor will be updated to point to the next ASN.1
+ * object. If any error occurs, the object cursor will be
+ * invalidated.
+ */
+int asn1_skip_object ( struct asn1_cursor *cursor, unsigned int type ) {
+ int len;
+
+ len = asn1_start_object ( cursor, type );
+ if ( len < 0 )
+ return -ENOENT;
+
+ cursor->data += len;
+ cursor->len -= len;
+ DBGC ( cursor, "ASN1 %p skipped object type %02x (len %x)\n",
+ cursor, type, len );
+
+ if ( ! cursor->len ) {
+ DBGC ( cursor, "ASN1 %p reached end of object\n", cursor );
+ cursor->data = NULL;
+ return -ENOENT;
+ }
+
+ return 0;
+}