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#define DEBUG 0
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#include <stdlib.h>
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#include <memory.h>
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#if DEBUG
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#include <stdio.h>
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#endif
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void msf_pattern_create(int length, char *patternStr) {
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    char upper      = 'A';
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    char lower      = 'a';
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    char num        = '0';
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    char c;
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    unsigned int i  = 0;
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    while (i != length) {
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        switch (i%3) {
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            case 0:
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                c = upper;
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                break;
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            case 1:
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                c = lower;
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                break;
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            case 2:
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                c = num;
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                if (num++ == '9') {
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                    num = '0';
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                    if (lower++ == 'z') {
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                        lower = 'a';
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                        if (upper++ == 'Z') {
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                            upper = 'A';
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                        }
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                    }
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                }
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                break;
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        }
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        patternStr[i] = c;
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        i++;
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    }
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}
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int msf_pattern_offset(int length, unsigned int needle) {
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    char            *patternStr;
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    unsigned int    *haystack;
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    if (length < 4)
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        return (-1);
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    patternStr =  (char *) malloc(length+1);
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    if (patternStr == NULL) {
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        return (-1);
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    }
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    memset(patternStr, 0x00, length+1);
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    msf_pattern_create(length, patternStr);
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    length -= 4;
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    while (length >= 0) {
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        haystack = (unsigned int *) &patternStr[length];
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        //printf("Haystack: 0x%08x\n", *haystack);
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        if (needle == *haystack)
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            break;
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        length--;
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    }
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    free(patternStr);
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    return (length);
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}
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#if DEBUG
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int main() {
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    char pattern[256];
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    char findme[] = "0Aa1";
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    memset(pattern, 0x00, 256);
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    msf_pattern_create(255, pattern);
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    printf("Pattern: %s\n", pattern);
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    printf("%s @ %d\n", findme, msf_pattern_offset(255, findme));
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    return (0);
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}
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#endif
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