69 lines
1.4 KiB
C
69 lines
1.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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//kbuild:lib-y += percent_decode.o
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#include "libbb.h"
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static unsigned hex_to_bin(unsigned char c)
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{
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unsigned v;
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v = c - '0';
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if (v <= 9)
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return v;
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/* c | 0x20: letters to lower case, non-letters
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* to (potentially different) non-letters */
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v = (unsigned)(c | 0x20) - 'a';
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if (v <= 5)
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return v + 10;
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return ~0;
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/* For testing:
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void t(char c) { printf("'%c'(%u) %u\n", c, c, hex_to_bin(c)); }
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int main() { t(0x10); t(0x20); t('0'); t('9'); t('A'); t('F'); t('a'); t('f');
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t('0'-1); t('9'+1); t('A'-1); t('F'+1); t('a'-1); t('f'+1); return 0; }
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*/
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}
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char* FAST_FUNC percent_decode_in_place(char *str, int strict)
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{
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/* note that decoded string is always shorter than original */
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char *src = str;
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char *dst = str;
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char c;
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while ((c = *src++) != '\0') {
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unsigned v;
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if (!strict && c == '+') {
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*dst++ = ' ';
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continue;
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}
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if (c != '%') {
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*dst++ = c;
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continue;
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}
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v = hex_to_bin(src[0]);
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if (v > 15) {
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bad_hex:
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if (strict)
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return NULL;
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*dst++ = '%';
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continue;
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}
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v = (v * 16) | hex_to_bin(src[1]);
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if (v > 255)
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goto bad_hex;
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if (strict && (v == '/' || v == '\0')) {
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/* caller takes it as indication of invalid
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* (dangerous wrt exploits) chars */
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return str + 1;
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}
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*dst++ = v;
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src += 2;
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}
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*dst = '\0';
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return str;
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}
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