gseDecodeBasic.c

00001 /**
00002  * Rapid-prototyping protection schemes with IEC 61850
00003  *
00004  * Copyright (c) 2012 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 fixed-length GOOSE. If not, check for 8 bits for exponent
00037         if (len == 5 && buf[offset] == 0x08) {
00038             netmemcpy(value, &buf[offset + 1], len - 1);
00039         }
00040         else if (len == 4) {
00041             netmemcpy(value, &buf[offset], len);
00042         }
00043     }
00044 
00045     return offset + len;
00046 }
00047 
00048 int BER_DECODE_CTYPE_FLOAT64(unsigned char *buf, CTYPE_FLOAT64 *value) {
00049     CTYPE_INT16U offset = 0;
00050     CTYPE_INT16U len = 0;
00051 
00052     if (buf[offset++] == 0x87) {
00053         len += decodeLength(&buf[offset]);
00054         offset += getLengthFieldSize(buf[offset]);
00055 
00056         // check for fixed-length GOOSE. If not, check for 11 bits for exponent
00057         if (len == 9 && buf[offset] == 0x0B) {
00058             netmemcpy(value, &buf[offset + 1], len - 1);
00059         }
00060         else if (len == 8) {
00061             netmemcpy(value, &buf[offset], len);
00062         }
00063     }
00064 
00065     return offset + len;
00066 }
00067 int BER_DECODE_CTYPE_QUALITY(unsigned char *buf, CTYPE_QUALITY *value) {
00068     CTYPE_INT16U offset = 0;
00069     CTYPE_INT16U len = 0;
00070 
00071     if (buf[offset] == ASN1_TAG_BIT_STRING) {
00072         offset++;
00073         len += decodeLength(&buf[offset]);
00074         offset += getLengthFieldSize(buf[offset]);
00075 
00076         netmemcpy(value, &buf[offset + 1], len - 1);    // skip over one byte (which contains number of unused bits)
00077     }
00078 
00079     return offset + len;
00080 }
00081 int BER_DECODE_CTYPE_TIMESTAMP(unsigned char *buf, CTYPE_TIMESTAMP *value) {
00082     CTYPE_INT16U offset = 0;
00083     CTYPE_INT16U len = 0;
00084 
00085     if (buf[offset++] == 0x89) {
00086         len += decodeLength(&buf[offset]);
00087         offset += getLengthFieldSize(buf[offset]);
00088 
00089         netmemcpy(value, &buf[offset], len);
00090     }
00091 
00092     return offset + len;
00093 }
00094 int BER_DECODE_CTYPE_ENUM(unsigned char *buf, CTYPE_ENUM *value) {    // assuming enum is an int - allows any enum type to be used
00095     CTYPE_INT16U offset = 0;
00096     CTYPE_INT16U len = 0;
00097 
00098     if (buf[offset++] == ASN1_TAG_UNSIGNED) {
00099         len += decodeLength(&buf[offset]);
00100         offset += getLengthFieldSize(buf[offset]);
00101 
00102 #if GOOSE_FIXED_SIZE == 1
00103         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT8);
00104 #else
00105         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT32U);
00106 #endif
00107     }
00108 
00109     return offset + len;
00110 }
00111 int BER_DECODE_CTYPE_INT8(unsigned char *buf, CTYPE_INT8 *value) {
00112     CTYPE_INT16U offset = 0;
00113     CTYPE_INT16U len = 0;
00114 
00115     if (buf[offset++] == ASN1_TAG_INTEGER) {
00116         len += decodeLength(&buf[offset]);
00117         offset += getLengthFieldSize(buf[offset]);
00118 
00119         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT8);
00120     }
00121 
00122     return offset + len;
00123 }
00124 int BER_DECODE_CTYPE_INT16(unsigned char *buf, CTYPE_INT16 *value) {
00125     CTYPE_INT16U offset = 0;
00126     CTYPE_INT16U len = 0;
00127 
00128     if (buf[offset++] == ASN1_TAG_INTEGER) {
00129         len += decodeLength(&buf[offset]);
00130         offset += getLengthFieldSize(buf[offset]);
00131 
00132         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT16);
00133     }
00134 
00135     return offset + len;
00136 }
00137 int BER_DECODE_CTYPE_INT32(unsigned char *buf, CTYPE_INT32 *value) {
00138     CTYPE_INT16U offset = 0;
00139     CTYPE_INT16U len = 0;
00140 
00141     if (buf[offset++] == ASN1_TAG_INTEGER) {
00142         len += decodeLength(&buf[offset]);
00143         offset += getLengthFieldSize(buf[offset]);
00144 
00145         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT32);
00146     }
00147 
00148     return offset + len;
00149 }
00150 int BER_DECODE_CTYPE_INT16U(unsigned char *buf, CTYPE_INT16U *value) {
00151     CTYPE_INT16U offset = 0;
00152     CTYPE_INT16U len = 0;
00153 
00154     if (buf[offset++] == ASN1_TAG_UNSIGNED) {
00155         len += decodeLength(&buf[offset]);
00156         offset += getLengthFieldSize(buf[offset]);
00157 
00158         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT16U);
00159     }
00160 
00161     return offset + len;
00162 }
00163 int BER_DECODE_CTYPE_INT32U(unsigned char *buf, CTYPE_INT32U *value) {
00164     CTYPE_INT16U offset = 0;
00165     CTYPE_INT16U len = 0;
00166 
00167     if (buf[offset++] == ASN1_TAG_UNSIGNED) {
00168         len += decodeLength(&buf[offset]);
00169         offset += getLengthFieldSize(buf[offset]);
00170 
00171         ber_decode_integer(&buf[offset], len, value, SV_GET_LENGTH_INT32U);
00172     }
00173 
00174     return offset + len;
00175 }
00176 int BER_DECODE_CTYPE_VISSTRING255(unsigned char *buf, CTYPE_VISSTRING255 *value) {
00177     netmemcpy(value, buf, SV_GET_LENGTH_VISSTRING255);
00178 
00179     return SV_GET_LENGTH_VISSTRING255;
00180 }
00181 int BER_DECODE_CTYPE_BOOLEAN(unsigned char *buf, CTYPE_BOOLEAN *value) {
00182     CTYPE_INT16U offset = 0;
00183     CTYPE_INT16U len = 0;
00184 
00185     if (buf[offset++] == ASN1_TAG_BOOLEAN) {
00186         len += decodeLength(&buf[offset]);
00187         offset += getLengthFieldSize(buf[offset]);
00188 
00189         netmemcpy(value, &buf[offset], len);
00190     }
00191 
00192     return offset + len;
00193 }
00194 int BER_DECODE_CTYPE_DBPOS(unsigned char *buf, CTYPE_DBPOS *value) {
00195     netmemcpy(value, buf, SV_GET_LENGTH_DBPOS);
00196 
00197     return SV_GET_LENGTH_DBPOS;
00198 }