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Annotation of qemu/roms/ipxe/src/crypto/asn1.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (C) 2007 Michael Brown <[email protected]>.
        !             3:  *
        !             4:  * This program is free software; you can redistribute it and/or
        !             5:  * modify it under the terms of the GNU General Public License as
        !             6:  * published by the Free Software Foundation; either version 2 of the
        !             7:  * License, or any later version.
        !             8:  *
        !             9:  * This program is distributed in the hope that it will be useful, but
        !            10:  * WITHOUT ANY WARRANTY; without even the implied warranty of
        !            11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
        !            12:  * General Public License for more details.
        !            13:  *
        !            14:  * You should have received a copy of the GNU General Public License
        !            15:  * along with this program; if not, write to the Free Software
        !            16:  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            17:  */
        !            18: 
        !            19: FILE_LICENCE ( GPL2_OR_LATER );
        !            20: 
        !            21: #include <stdint.h>
        !            22: #include <stddef.h>
        !            23: #include <errno.h>
        !            24: #include <ipxe/asn1.h>
        !            25: 
        !            26: /** @file
        !            27:  *
        !            28:  * ASN.1 encoding
        !            29:  *
        !            30:  */
        !            31: 
        !            32: /**
        !            33:  * Start parsing ASN.1 object
        !            34:  *
        !            35:  * @v cursor           ASN.1 object cursor
        !            36:  * @v type             Expected type
        !            37:  * @ret len            Length of object body, or negative error
        !            38:  *
        !            39:  * The object cursor will be updated to point to the start of the
        !            40:  * object body (i.e. the first byte following the length byte(s)), and
        !            41:  * the length of the object body (i.e. the number of bytes until the
        !            42:  * following object tag, if any) is returned.
        !            43:  *
        !            44:  * If any error occurs (i.e. if the object is not of the expected
        !            45:  * type, or if we overflow beyond the end of the ASN.1 object), then
        !            46:  * the cursor will be invalidated and a negative value will be
        !            47:  * returned.
        !            48:  */
        !            49: static int asn1_start ( struct asn1_cursor *cursor,
        !            50:                               unsigned int type ) {
        !            51:        unsigned int len_len;
        !            52:        unsigned int len;
        !            53:        int rc;
        !            54: 
        !            55:        /* Sanity check */
        !            56:        if ( cursor->len < 2 /* Tag byte and first length byte */ ) {
        !            57:                if ( cursor->len )
        !            58:                        DBGC ( cursor, "ASN1 %p too short\n", cursor );
        !            59:                rc = -EINVAL;
        !            60:                goto notfound;
        !            61:        }
        !            62: 
        !            63:        /* Check the tag byte */
        !            64:        if ( *( ( uint8_t * ) cursor->data ) != type ) {
        !            65:                DBGC ( cursor, "ASN1 %p type mismatch (expected %d, got %d)\n",
        !            66:                       cursor, type, *( ( uint8_t * ) cursor->data ) );
        !            67:                rc = -ENXIO;
        !            68:                goto notfound;
        !            69:        }
        !            70:        cursor->data++;
        !            71:        cursor->len--;
        !            72: 
        !            73:        /* Extract length of the length field and sanity check */
        !            74:        len_len = *( ( uint8_t * ) cursor->data );
        !            75:        if ( len_len & 0x80 ) {
        !            76:                len_len = ( len_len & 0x7f );
        !            77:                cursor->data++;
        !            78:                cursor->len--;
        !            79:        } else {
        !            80:                len_len = 1;
        !            81:        }
        !            82:        if ( cursor->len < len_len ) {
        !            83:                DBGC ( cursor, "ASN1 %p bad length field length %d (max "
        !            84:                       "%zd)\n", cursor, len_len, cursor->len );
        !            85:                rc = -EINVAL;
        !            86:                goto notfound;
        !            87:        }
        !            88: 
        !            89:        /* Extract the length and sanity check */
        !            90:        for ( len = 0 ; len_len ; len_len-- ) {
        !            91:                len <<= 8;
        !            92:                len |= *( ( uint8_t * ) cursor->data );
        !            93:                cursor->data++;
        !            94:                cursor->len--;
        !            95:        }
        !            96:        if ( cursor->len < len ) {
        !            97:                DBGC ( cursor, "ASN1 %p bad length %d (max %zd)\n",
        !            98:                       cursor, len, cursor->len );
        !            99:                rc = -EINVAL;
        !           100:                goto notfound;
        !           101:        }
        !           102: 
        !           103:        return len;
        !           104: 
        !           105:  notfound:
        !           106:        cursor->data = NULL;
        !           107:        cursor->len = 0;
        !           108:        return rc;
        !           109: }
        !           110: 
        !           111: /**
        !           112:  * Enter ASN.1 object
        !           113:  *
        !           114:  * @v cursor           ASN.1 object cursor
        !           115:  * @v type             Expected type
        !           116:  * @ret rc             Return status code
        !           117:  *
        !           118:  * The object cursor will be updated to point to the body of the
        !           119:  * current ASN.1 object.  If any error occurs, the object cursor will
        !           120:  * be invalidated.
        !           121:  */
        !           122: int asn1_enter ( struct asn1_cursor *cursor, unsigned int type ) {
        !           123:        int len;
        !           124: 
        !           125:        len = asn1_start ( cursor, type );
        !           126:        if ( len < 0 )
        !           127:                return len;
        !           128: 
        !           129:        cursor->len = len;
        !           130:        DBGC ( cursor, "ASN1 %p entered object type %02x (len %x)\n",
        !           131:               cursor, type, len );
        !           132: 
        !           133:        return 0;
        !           134: }
        !           135: 
        !           136: /**
        !           137:  * Skip ASN.1 object
        !           138:  *
        !           139:  * @v cursor           ASN.1 object cursor
        !           140:  * @v type             Expected type
        !           141:  * @ret rc             Return status code
        !           142:  *
        !           143:  * The object cursor will be updated to point to the next ASN.1
        !           144:  * object.  If any error occurs, the object cursor will be
        !           145:  * invalidated.
        !           146:  */
        !           147: int asn1_skip ( struct asn1_cursor *cursor, unsigned int type ) {
        !           148:        int len;
        !           149: 
        !           150:        len = asn1_start ( cursor, type );
        !           151:        if ( len < 0 )
        !           152:                return len;
        !           153: 
        !           154:        cursor->data += len;
        !           155:        cursor->len -= len;
        !           156:        DBGC ( cursor, "ASN1 %p skipped object type %02x (len %x)\n",
        !           157:               cursor, type, len );
        !           158: 
        !           159:        if ( ! cursor->len ) {
        !           160:                DBGC ( cursor, "ASN1 %p reached end of object\n", cursor );
        !           161:                cursor->data = NULL;
        !           162:                return -ENOENT;
        !           163:        }
        !           164: 
        !           165:        return 0;
        !           166: }

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