diff options
Diffstat (limited to 'roms/ipxe/src/crypto/asn1.c')
| -rw-r--r-- | roms/ipxe/src/crypto/asn1.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/roms/ipxe/src/crypto/asn1.c b/roms/ipxe/src/crypto/asn1.c new file mode 100644 index 000000000..a54d31d0c --- /dev/null +++ b/roms/ipxe/src/crypto/asn1.c @@ -0,0 +1,166 @@ +/* + * 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. + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +#include <stdint.h> +#include <stddef.h> +#include <errno.h> +#include <ipxe/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 negative 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 ( struct asn1_cursor *cursor, + unsigned int type ) { + unsigned int len_len; + unsigned int len; + int rc; + + /* Sanity check */ + if ( cursor->len < 2 /* Tag byte and first length byte */ ) { + if ( cursor->len ) + DBGC ( cursor, "ASN1 %p too short\n", cursor ); + rc = -EINVAL; + goto notfound; + } + + /* Check the tag byte */ + if ( *( ( uint8_t * ) cursor->data ) != type ) { + DBGC ( cursor, "ASN1 %p type mismatch (expected %d, got %d)\n", + cursor, type, *( ( uint8_t * ) cursor->data ) ); + rc = -ENXIO; + goto notfound; + } + cursor->data++; + cursor->len--; + + /* Extract length of the length field and sanity check */ + len_len = *( ( uint8_t * ) cursor->data ); + 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 ); + rc = -EINVAL; + goto notfound; + } + + /* Extract the length and sanity check */ + for ( len = 0 ; len_len ; len_len-- ) { + len <<= 8; + len |= *( ( uint8_t * ) cursor->data ); + cursor->data++; + cursor->len--; + } + if ( cursor->len < len ) { + DBGC ( cursor, "ASN1 %p bad length %d (max %zd)\n", + cursor, len, cursor->len ); + rc = -EINVAL; + goto notfound; + } + + return len; + + notfound: + cursor->data = NULL; + cursor->len = 0; + return rc; +} + +/** + * 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 ( struct asn1_cursor *cursor, unsigned int type ) { + int len; + + len = asn1_start ( cursor, type ); + if ( len < 0 ) + return len; + + 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 ( struct asn1_cursor *cursor, unsigned int type ) { + int len; + + len = asn1_start ( cursor, type ); + if ( len < 0 ) + return len; + + 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; +} |