gseDecodeBasic.c

00001 /**
00002  * Rapid-prototyping protection schemes with IEC 61850
00003  *
00004  * Copyright (c) 2011 Steven Blair
00005  * 
00006  * This program is free software; you can redistribute it and/or
00007  * modify it under the terms of the GNU General Public License
00008  * as published by the Free Software Foundation; either version 2
00009  * of the License, or (at your option) any later version.
00010 
00011  * This program is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014  * GNU General Public License for more details.
00015 
00016  * You should have received a copy of the GNU General Public License
00017  * along with this program; if not, write to the Free Software
00018  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
00019  */
00020 
00021 #include "ctypes.h"
00022 #include "datatypes.h"
00023 #include "ied.h"
00024 #include "gseDecodeBasic.h"
00025 #include <string.h>
00026 
00027 // GSE decoding of basic types
00028 int BER_DECODE_CTYPE_FLOAT32(unsigned char *buf, CTYPE_FLOAT32 *value) {
00029     CTYPE_INT16U offset = 0;
00030     CTYPE_INT16U len = 0;
00031 
00032     if (buf[offset++] == 0x87) {
00033         len += decodeLength(&buf[offset]);
00034         offset += getLengthFieldSize(buf[offset]);
00035 
00036         // check for 8 bits for exponent
00037         if (buf[offset++] == 0x08) {
00038             netmemcpy(value, &buf[offset], len - 1);
00039         }
00040     }
00041 
00042     return offset + len - 1;
00043 }
00044 
00045 // GSE decoding of basic types
00046 int BER_DECODE_CTYPE_FLOAT64(unsigned char *buf, CTYPE_FLOAT64 *value) {
00047     CTYPE_INT16U offset = 0;
00048     CTYPE_INT16U len = 0;
00049 
00050     if (buf[offset++] == 0x87) {
00051         len += decodeLength(&buf[offset]);
00052         offset += getLengthFieldSize(buf[offset]);
00053 
00054         // check for 11 bits for exponent
00055         if (buf[offset++] == 0x0B) {
00056             netmemcpy(value, &buf[offset], len - 1);
00057         }
00058     }
00059 
00060     return offset + len - 1;
00061 }
00062 int BER_DECODE_CTYPE_QUALITY(unsigned char *buf, CTYPE_QUALITY *value) {
00063     CTYPE_INT16U offset = 0;
00064     CTYPE_INT16U len = 0;
00065 
00066     if (buf[offset++] == 0x85) {
00067         len += decodeLength(&buf[offset]);
00068         offset += getLengthFieldSize(buf[offset]);
00069 
00070         netmemcpy(value, buf, len);        //TODO check if memcpy should be used here, and elsewhere
00071     }
00072 
00073     return offset + len;
00074 }
00075 int BER_DECODE_CTYPE_TIMESTAMP(unsigned char *buf, CTYPE_TIMESTAMP *value) {
00076     CTYPE_INT16U offset = 0;
00077     CTYPE_INT16U len = 0;
00078 
00079     if (buf[offset++] == 0x89) {
00080         len += decodeLength(&buf[offset]);
00081         offset += getLengthFieldSize(buf[offset]);
00082 
00083         netmemcpy(value, buf, len);
00084     }
00085 
00086     return offset + len;
00087 }
00088 int BER_DECODE_CTYPE_ENUM(unsigned char *buf, CTYPE_ENUM *value) {    // assuming enum is an int - allows any enum type to be used
00089     CTYPE_INT16U offset = 0;
00090     CTYPE_INT16U len = 0;
00091 
00092     if (buf[offset++] == ASN1_TAG_UNSIGNED) {
00093         len += decodeLength(&buf[offset]);
00094         offset += getLengthFieldSize(buf[offset]);
00095 
00096         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT32U);
00097     }
00098 
00099     return offset + len;
00100 }
00101 int BER_DECODE_CTYPE_INT16(unsigned char *buf, CTYPE_INT16 *value) {
00102     CTYPE_INT16U offset = 0;
00103     CTYPE_INT16U len = 0;
00104 
00105     if (buf[offset++] == ASN1_TAG_INTEGER) {
00106         len += decodeLength(&buf[offset]);
00107         offset += getLengthFieldSize(buf[offset]);
00108 
00109         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT16);
00110     }
00111 
00112     return offset + len;
00113 }
00114 int BER_DECODE_CTYPE_INT32(unsigned char *buf, CTYPE_INT32 *value) {
00115     CTYPE_INT16U offset = 0;
00116     CTYPE_INT16U len = 0;
00117 
00118     if (buf[offset++] == ASN1_TAG_INTEGER) {
00119         len += decodeLength(&buf[offset]);
00120         offset += getLengthFieldSize(buf[offset]);
00121 
00122         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT32);
00123     }
00124 
00125     return offset + len;
00126 }
00127 int BER_DECODE_CTYPE_INT16U(unsigned char *buf, CTYPE_INT16U *value) {
00128     CTYPE_INT16U offset = 0;
00129     CTYPE_INT16U len = 0;
00130 
00131     if (buf[offset++] == ASN1_TAG_UNSIGNED) {
00132         len += decodeLength(&buf[offset]);
00133         offset += getLengthFieldSize(buf[offset]);
00134 
00135         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT16U);
00136     }
00137 
00138     return offset + len;
00139 }
00140 int BER_DECODE_CTYPE_INT32U(unsigned char *buf, CTYPE_INT32U *value) {
00141     CTYPE_INT16U offset = 0;
00142     CTYPE_INT16U len = 0;
00143 
00144     if (buf[offset++] == ASN1_TAG_UNSIGNED) {
00145         len += decodeLength(&buf[offset]);
00146         offset += getLengthFieldSize(buf[offset]);
00147 
00148         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT32U);
00149     }
00150 
00151     return offset + len;
00152 }
00153 int BER_DECODE_CTYPE_VISSTRING255(unsigned char *buf, CTYPE_VISSTRING255 *value) {
00154     netmemcpy(value, buf, SV_GET_LENGTH_VISSTRING255);
00155 
00156     return SV_GET_LENGTH_VISSTRING255;
00157 }
00158 int BER_DECODE_CTYPE_BOOLEAN(unsigned char *buf, CTYPE_BOOLEAN *value) {
00159     CTYPE_INT16U offset = 0;
00160     CTYPE_INT16U len = 0;
00161 
00162     if (buf[offset++] == ASN1_TAG_BOOLEAN) {
00163         len += decodeLength(&buf[offset]);
00164         offset += getLengthFieldSize(buf[offset]);
00165 
00166         netmemcpy(value, buf, len);
00167     }
00168 
00169     return offset + len;
00170 }
00171 int BER_DECODE_CTYPE_DBPOS(unsigned char *buf, CTYPE_DBPOS *value) {
00172     netmemcpy(value, buf, SV_GET_LENGTH_DBPOS);
00173 
00174     return SV_GET_LENGTH_DBPOS;
00175 }