//-----------------------------------------------------------------------------
// Copyright (C) 2015 iceman <iceman at iuse.se>
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// CRC Calculations from the software reveng commands
//-----------------------------------------------------------------------------
#include "cmdcrc.h"
#define MAX_ARGS 20
static int split(char *str, char *arr[MAX_ARGS]) {
int beginIndex = 0;
int endIndex;
int maxWords = MAX_ARGS;
int wordCnt = 0;
while (1) {
while (isspace(str[beginIndex])) {
++beginIndex;
}
if (str[beginIndex] == '\0') {
break;
}
endIndex = beginIndex;
while (str[endIndex] && !isspace(str[endIndex])) {
++endIndex;
}
int len = endIndex - beginIndex;
char *tmp = calloc(len + 1, sizeof(char));
memcpy(tmp, &str[beginIndex], len);
arr[wordCnt++] = tmp;
beginIndex = endIndex;
if (wordCnt == maxWords)
break;
}
return wordCnt;
}
//returns array of model names and the count of models returning
// as well as a width array for the width of each model
int GetModels(char *Models[], int *count, uint8_t *width) {
/* default values */
static model_t model = MZERO;
int ibperhx = 8;//, obperhx = 8;
int rflags = 0, uflags = 0; /* search and UI flags */
poly_t apoly, crc, qpoly = PZERO, *apolys = NULL, *pptr = NULL, *qptr = NULL;
model_t pset = model, *candmods, *mptr;
/* stdin must be binary */
#ifdef _WIN32
_setmode(STDIN_FILENO, _O_BINARY);
#endif /* _WIN32 */
SETBMP();
if (width[0] == 0) { //reveng -D
*count = mcount();
if (!*count) {
PrintAndLogEx(WARNING, "no preset models available");
return 0;
}
for (int mode = 0; mode < *count; ++mode) {
mbynum(&model, mode);
mcanon(&model);
size_t size = (model.name && *model.name) ? strlen(model.name) : 7;
char *tmp = calloc(size + 1, sizeof(char));
if (tmp == NULL) {
PrintAndLogEx(WARNING, "out of memory?");
return 0;
}
if (model.name != NULL) {
memcpy(tmp, model.name, size);
Models[mode] = tmp;
width[mode] = plen(model.spoly);
}
}
mfree(&model);
} else { //reveng -s
if (~model.flags & P_MULXN) {
PrintAndLogEx(WARNING, "cannot search for non-Williams compliant models");
return 0;
}
praloc(&model.spoly, (unsigned long)width[0]);
praloc(&model.init, (unsigned long)width[0]);
praloc(&model.xorout, (unsigned long)width[0]);
if (!plen(model.spoly))
palloc(&model.spoly, (unsigned long)width[0]);
else
width[0] = (uint8_t)plen(model.spoly);
/* special case if qpoly is zero, search to end of range */
if (!ptst(qpoly))
rflags &= ~R_HAVEQ;
int pass;
/* if endianness not specified, try
* little-endian then big-endian.
* NB: crossed-endian algorithms will not be
* searched.
*/
/* scan against preset models */
if (~uflags & C_NOPCK) {
pass = 0;
int Cnt = 0, psets;
do {
psets = mcount();
while (psets) {
mbynum(&pset, --psets);
/* skip if different width, or refin or refout don't match */
if (plen(pset.spoly) != width[0] || (model.flags ^ pset.flags) & (P_REFIN | P_REFOUT))
continue;
/* skip if the preset doesn't match specified parameters */
if (rflags & R_HAVEP && pcmp(&model.spoly, &pset.spoly))
continue;
if (rflags & R_HAVEI && psncmp(&model.init, &pset.init))
continue;
if (rflags & R_HAVEX && psncmp(&model.xorout, &pset.xorout))
continue;
//for additional args (not used yet, maybe future?)
apoly = pclone(pset.xorout);
if (pset.flags & P_REFOUT)
prev(&apoly);
for (qptr = apolys; qptr < pptr; ++qptr) {
crc = pcrc(*qptr, pset.spoly, pset.init, apoly, 0);
if (ptst(crc)) {
pfree(&crc);
break;
}
pfree(&crc);
}
pfree(&apoly);
if (qptr == pptr) {
/* the selected model solved all arguments */
mcanon(&pset);
size_t size = (pset.name && *pset.name) ? strlen(pset.name) : 7;
//PrintAndLogEx(NORMAL, "Size: %d, %s, count: %d",size,pset.name, Cnt);
char *tmp = calloc(size + 1, sizeof(char));
if (tmp == NULL) {
PrintAndLogEx(WARNING, "out of memory?");
return 0;
}
width[Cnt] = width[0];
memcpy(tmp, pset.name, size);
Models[Cnt++] = tmp;
*count = Cnt;
uflags |= C_RESULT;
}
}
mfree(&pset);
/* toggle refIn/refOut and reflect arguments */
if (~rflags & R_HAVERI) {
model.flags ^= P_REFIN | P_REFOUT;
for (qptr = apolys; qptr < pptr; ++qptr) {
prevch(qptr, ibperhx);
}
}
} while (~rflags & R_HAVERI && ++pass < 2);
}
//got everything now free the memory...
if (uflags & C_RESULT) {
for (qptr = apolys; qptr < pptr; ++qptr) {
pfree(qptr);
}
}
if (uflags & C_NOBFS && ~rflags & R_HAVEP) {
PrintAndLogEx(WARNING, "no models found");
return 0;
}
if (!(model.flags & P_REFIN) != !(model.flags & P_REFOUT)) {
PrintAndLogEx(WARNING, "cannot search for crossed-endian models");
return 0;
}
pass = 0;
int args = 0;
do {
mptr = candmods = reveng(&model, qpoly, rflags, args, apolys);
if (mptr && plen(mptr->spoly)) {
uflags |= C_RESULT;
}
while (mptr && plen(mptr->spoly)) {
mfree(mptr++);
}
free(candmods);
if (~rflags & R_HAVERI) {
model.flags ^= P_REFIN | P_REFOUT;
for (qptr = apolys; qptr < pptr; ++qptr) {
prevch(qptr, ibperhx);
}
}
} while (~rflags & R_HAVERI && ++pass < 2);
for (qptr = apolys; qptr < pptr; ++qptr) {
pfree(qptr);
}
free(apolys);
mfree(&model);
if (~uflags & C_RESULT) {
PrintAndLogEx(WARNING, "no models found");
return 0;
}
}
return 1;
}
//-c || -v
//inModel = valid model name string - CRC-8
//inHexStr = input hex string to calculate crc on
//reverse = reverse calc option if true
//endian = {0 = calc default endian input and output, b = big endian input and output, B = big endian output, r = right justified
// l = little endian input and output, L = little endian output only, t = left justified}
//result = calculated crc hex string
int RunModel(char *inModel, char *inHexStr, bool reverse, char endian, char *result) {
/* default values */
static model_t model = MZERO;
int ibperhx = 8, obperhx = 8;
// int rflags = 0; // search flags
int c;
poly_t apoly, crc;
char *string;
// stdin must be binary
#ifdef _WIN32
_setmode(STDIN_FILENO, _O_BINARY);
#endif /* _WIN32 */
SETBMP();
//set model
c = mbynam(&model, inModel);
if (!c) {
PrintAndLogEx(WARNING, "error: preset model '%s' not found. Use reveng -D to list presets. [%d]", inModel, c);
return 0;
}
if (c < 0) {
PrintAndLogEx(WARNING, "no preset models available");
return 0;
}
// rflags |= R_HAVEP | R_HAVEI | R_HAVERI | R_HAVERO | R_HAVEX;
//set flags
switch (endian) {
case 'b': /* b big-endian (RefIn = false, RefOut = false ) */
model.flags &= ~P_REFIN;
//rflags |= R_HAVERI;
/* fall through: */
case 'B': /* B big-endian output (RefOut = false) */
model.flags &= ~P_REFOUT;
//rflags |= R_HAVERO;
mnovel(&model);
/* fall through: */
case 'r': /* r right-justified */
model.flags |= P_RTJUST;
break;
case 'l': /* l little-endian input and output */
model.flags |= P_REFIN;
//rflags |= R_HAVERI;
/* fall through: */
case 'L': /* L little-endian output */
model.flags |= P_REFOUT;
//rflags |= R_HAVERO;
mnovel(&model);
/* fall through: */
case 't': /* t left-justified */
model.flags &= ~P_RTJUST;
break;
}
/* canonicalise the model, so the one we dump is the one we
* calculate with (not with -s, spoly may be blank which will
* normalise to zero and clear init and xorout.)
*/
mcanon(&model);
if (reverse) {
// v calculate reversed CRC
/* Distinct from the -V switch as this causes
* the arguments and output to be reversed as well.
*/
// reciprocate Poly
prcp(&model.spoly);
/* mrev() does:
* if(refout) prev(init); else prev(xorout);
* but here the entire argument polynomial is
* reflected, not just the characters, so RefIn
* and RefOut are not inverted as with -V.
* Consequently Init is the mirror image of the
* one resulting from -V, and so we have:
*/
if (~model.flags & P_REFOUT) {
prev(&model.init);
prev(&model.xorout);
}
// swap init and xorout
apoly = model.init;
model.init = model.xorout;
model.xorout = apoly;
}
// c calculate CRC
/* in the Williams model, xorout is applied after the refout stage.
* as refout is part of ptostr(), we reverse xorout here.
*/
if (model.flags & P_REFOUT)
prev(&model.xorout);
apoly = strtop(inHexStr, model.flags, ibperhx);
if (reverse)
prev(&apoly);
crc = pcrc(apoly, model.spoly, model.init, model.xorout, model.flags);
if (reverse)
prev(&crc);
string = ptostr(crc, model.flags, obperhx);
for (int i = 0; i < 50; i++) {
result[i] = string[i];
if (result[i] == 0) break;
}
free(string);
pfree(&crc);
pfree(&apoly);
return 1;
}
/*
//test call to RunModel
static int CmdrevengTestC(const char *Cmd) {
int cmdp = 0;
char inModel[30] = {0x00};
char inHexStr[30] = {0x00};
char result[30];
int dataLen;
char endian = 0;
dataLen = param_getstr(Cmd, cmdp++, inModel, sizeof(inModel));
if (dataLen < 4) return 0;
dataLen = param_getstr(Cmd, cmdp++, inHexStr, sizeof(inHexStr));
if (dataLen < 4) return 0;
bool reverse = (param_get8(Cmd, cmdp++)) ? true : false;
endian = param_getchar(Cmd, cmdp++);
//PrintAndLogEx(NORMAL, "mod: %s, hex: %s, rev %d", inModel, inHexStr, reverse);
int ans = RunModel(inModel, inHexStr, reverse, endian, result);
if (!ans) return 0;
PrintAndLogEx(SUCCESS, "result: %s", result);
return 1;
}
*/
//returns a calloced string (needs to be freed)
static char *SwapEndianStr(const char *inStr, const size_t len, const uint8_t blockSize) {
char *tmp = calloc(len + 1, sizeof(char));
for (uint8_t block = 0; block < (uint8_t)(len / blockSize); block++) {
for (size_t i = 0; i < blockSize; i += 2) {
tmp[i + (blockSize * block)] = inStr[(blockSize - 1 - i - 1) + (blockSize * block)];
tmp[i + (blockSize * block) + 1] = inStr[(blockSize - 1 - i) + (blockSize * block)];
}
}
return tmp;
}
// takes hex string in and searches for a matching result (hex string must include checksum)
static int CmdrevengSearch(const char *Cmd) {
#define NMODELS 106
char inHexStr[100] = {0x00};
int dataLen = param_getstr(Cmd, 0, inHexStr, sizeof(inHexStr));
if (dataLen < 4) return 0;
// these two arrays, must match preset size.
char *Models[NMODELS];
uint8_t width[NMODELS] = {0};
int count = 0;
uint8_t crcChars;
char result[30];
char revResult[30];
int ans = GetModels(Models, &count, width);
bool found = false;
if (!ans) return 0;
// try each model and get result
for (int i = 0; i < count; i++) {
/*if (found) {
free(Models[i]);
continue;
}*/
// round up to # of characters in this model's crc
crcChars = ((width[i] + 7) / 8) * 2;
// can't test a model that has more crc digits than our data
if (crcChars >= dataLen)
continue;
PrintAndLogEx(DEBUG
, "DEBUG: dataLen %d, crcChars %u, width[i] %u"
, dataLen
, crcChars
, width[i]
);
if (crcChars == 0)
continue;
memset(result, 0, 30);
char *inCRC = calloc(crcChars + 1, sizeof(char));
memcpy(inCRC, inHexStr + (dataLen - crcChars), crcChars);
char *outHex = calloc(dataLen - crcChars + 1, sizeof(char));
memcpy(outHex, inHexStr, dataLen - crcChars);
ans = RunModel(Models[i], outHex, false, 0, result);
if (ans) {
// test for match
if (memcmp(result, inCRC, crcChars) == 0) {
PrintAndLogEx(SUCCESS, "\nfound possible match\nmodel: %s | value: %s\n", Models[i], result);
//optional - stop searching if found...
found = true;
} else {
if (crcChars > 2) {
char *swapEndian = SwapEndianStr(result, crcChars, crcChars);
if (memcmp(swapEndian, inCRC, crcChars) == 0) {
PrintAndLogEx(SUCCESS, "\nfound possible match\nmodel: %s | value endian swapped: %s\n", Models[i], swapEndian);
// optional - stop searching if found...
found = true;
}
free(swapEndian);
}
}
}
ans = RunModel(Models[i], outHex, true, 0, revResult);
if (ans) {
// test for match
if (memcmp(revResult, inCRC, crcChars) == 0) {
PrintAndLogEx(SUCCESS, "\nfound possible match\nmodel reversed: %s | value: %s\n", Models[i], revResult);
// optional - stop searching if found...
found = true;
} else {
if (crcChars > 2) {
char *swapEndian = SwapEndianStr(revResult, crcChars, crcChars);
if (memcmp(swapEndian, inCRC, crcChars) == 0) {
PrintAndLogEx(SUCCESS, "\nfound possible match\nmodel reversed: %s | value endian swapped: %s\n", Models[i], swapEndian);
// optional - stop searching if found...
found = true;
}
free(swapEndian);
}
}
}
free(inCRC);
free(outHex);
free(Models[i]);
}
if (!found) PrintAndLogEx(FAILED, "\nno matches found\n");
return 1;
}
int CmdCrc(const char *Cmd) {
char name[] = {"reveng "};
char Cmd2[100 + 7];
memcpy(Cmd2, name, 7);
memcpy(Cmd2 + 7, Cmd, 100);
char *argv[MAX_ARGS];
int argc = split(Cmd2, argv);
if (argc == 3 && memcmp(argv[1], "-g", 2) == 0) {
CmdrevengSearch(argv[2]);
} else {
reveng_main(argc, argv);
}
for (int i = 0; i < argc; ++i) {
free(argv[i]);
}
return 0;
}