bsd/libkern/url_encode.c

   1 /*
   2  * Copyright (c) 2016 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <libkern/libkern.h>
  30
  31 static int
  32 hex2int(int c)
  33 {
  34         if (c >= '0' && c <= '9') {
  35                 return c - '0';
  36         } else if (c >= 'A' && c <= 'F') {
  37                 return c - 'A' + 10;
  38         } else if (c >= 'a' && c <= 'f') {
  39                 return c - 'a' + 10;
  40         }
  41         return 0;
  42 }
  43
  44 static bool
  45 isprint(int ch)
  46 {
  47         return ch >= 0x20 && ch <= 0x7e;
  48 }
  49
  50 /*
  51  * In-place decode of URL percent-encoded str
  52  */
  53 void
  54 url_decode(char *str)
  55 {
  56         if (!str) {
  57                 return;
  58         }
  59
  60         while (*str) {
  61                 if (*str == '%') {
  62                         char c = 0;
  63                         char *esc = str++; /* remember the start of the escape sequence */
  64
  65                         if (*str) {
  66                                 c += hex2int(*str++);
  67                         }
  68                         if (*str) {
  69                                 c = (c << 4) + hex2int(*str++);
  70                         }
  71
  72                         if (isprint(c)) {
  73                                 /* overwrite the '%' with the new char, and bump the rest of the
  74                                  * string down a few characters */
  75                                 *esc++ = c;
  76                                 str = memmove(esc, str, strlen(str)+1);
  77                         } else {
  78                                 str++;
  79                         }
  80
  81                 } else {
  82                         str++;
  83                 }
  84         }
  85 }