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      1 /*
      2  * libjingle
      3  * Copyright 2008, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #include "talk/base/urlencode.h"
     29 
     30 #include "talk/base/common.h"
     31 #include "talk/base/stringutils.h"
     32 
     33 static int HexPairValue(const char * code) {
     34   int value = 0;
     35   const char * pch = code;
     36   for (;;) {
     37     int digit = *pch++;
     38     if (digit >= '0' && digit <= '9') {
     39       value += digit - '0';
     40     }
     41     else if (digit >= 'A' && digit <= 'F') {
     42       value += digit - 'A' + 10;
     43     }
     44     else if (digit >= 'a' && digit <= 'f') {
     45       value += digit - 'a' + 10;
     46     }
     47     else {
     48       return -1;
     49     }
     50     if (pch == code + 2)
     51       return value;
     52     value <<= 4;
     53   }
     54 }
     55 
     56 int InternalUrlDecode(const char *source, char *dest,
     57                       bool encode_space_as_plus) {
     58   char * start = dest;
     59 
     60   while (*source) {
     61     switch (*source) {
     62     case '+':
     63       if (encode_space_as_plus) {
     64         *(dest++) = ' ';
     65       } else {
     66         *dest++ = *source;
     67       }
     68       break;
     69     case '%':
     70       if (source[1] && source[2]) {
     71         int value = HexPairValue(source + 1);
     72         if (value >= 0) {
     73           *(dest++) = value;
     74           source += 2;
     75         }
     76         else {
     77           *dest++ = '?';
     78         }
     79       }
     80       else {
     81         *dest++ = '?';
     82       }
     83       break;
     84     default:
     85       *dest++ = *source;
     86     }
     87     source++;
     88   }
     89 
     90   *dest = 0;
     91   return static_cast<int>(dest - start);
     92 }
     93 
     94 int UrlDecode(const char *source, char *dest) {
     95   return InternalUrlDecode(source, dest, true);
     96 }
     97 
     98 int UrlDecodeWithoutEncodingSpaceAsPlus(const char *source, char *dest) {
     99   return InternalUrlDecode(source, dest, false);
    100 }
    101 
    102 bool IsValidUrlChar(char ch, bool unsafe_only) {
    103   if (unsafe_only) {
    104     return !(ch <= ' ' || strchr("\\\"^&`<>[]{}", ch));
    105   } else {
    106     return isalnum(ch) || strchr("-_.!~*'()", ch);
    107   }
    108 }
    109 
    110 int InternalUrlEncode(const char *source, char *dest, unsigned int max,
    111                       bool encode_space_as_plus, bool unsafe_only) {
    112   static const char *digits = "0123456789ABCDEF";
    113   if (max == 0) {
    114     return 0;
    115   }
    116 
    117   char *start = dest;
    118   while (static_cast<unsigned>(dest - start) < max && *source) {
    119     unsigned char ch = static_cast<unsigned char>(*source);
    120     if (*source == ' ' && encode_space_as_plus && !unsafe_only) {
    121       *dest++ = '+';
    122     } else if (IsValidUrlChar(ch, unsafe_only)) {
    123       *dest++ = *source;
    124     } else {
    125       if (static_cast<unsigned>(dest - start) + 4 > max) {
    126         break;
    127       }
    128       *dest++ = '%';
    129       *dest++ = digits[(ch >> 4) & 0x0F];
    130       *dest++ = digits[       ch & 0x0F];
    131     }
    132     source++;
    133   }
    134   ASSERT(static_cast<unsigned int>(dest - start) < max);
    135   *dest = 0;
    136 
    137   return static_cast<int>(dest - start);
    138 }
    139 
    140 int UrlEncode(const char *source, char *dest, unsigned max) {
    141   return InternalUrlEncode(source, dest, max, true, false);
    142 }
    143 
    144 int UrlEncodeWithoutEncodingSpaceAsPlus(const char *source, char *dest,
    145                                         unsigned max) {
    146   return InternalUrlEncode(source, dest, max, false, false);
    147 }
    148 
    149 int UrlEncodeOnlyUnsafeChars(const char *source, char *dest, unsigned max) {
    150   return InternalUrlEncode(source, dest, max, false, true);
    151 }
    152 
    153 std::string
    154 InternalUrlDecodeString(const std::string & encoded,
    155                         bool encode_space_as_plus) {
    156   size_t needed_length = encoded.length() + 1;
    157   char* buf = STACK_ARRAY(char, needed_length);
    158   InternalUrlDecode(encoded.c_str(), buf, encode_space_as_plus);
    159   return buf;
    160 }
    161 
    162 std::string
    163 UrlDecodeString(const std::string & encoded) {
    164   return InternalUrlDecodeString(encoded, true);
    165 }
    166 
    167 std::string
    168 UrlDecodeStringWithoutEncodingSpaceAsPlus(const std::string & encoded) {
    169   return InternalUrlDecodeString(encoded, false);
    170 }
    171 
    172 std::string
    173 InternalUrlEncodeString(const std::string & decoded,
    174                         bool encode_space_as_plus,
    175                         bool unsafe_only) {
    176   int needed_length = static_cast<int>(decoded.length()) * 3 + 1;
    177   char* buf = STACK_ARRAY(char, needed_length);
    178   InternalUrlEncode(decoded.c_str(), buf, needed_length,
    179                     encode_space_as_plus, unsafe_only);
    180   return buf;
    181 }
    182 
    183 std::string
    184 UrlEncodeString(const std::string & decoded) {
    185   return InternalUrlEncodeString(decoded, true, false);
    186 }
    187 
    188 std::string
    189 UrlEncodeStringWithoutEncodingSpaceAsPlus(const std::string & decoded) {
    190   return InternalUrlEncodeString(decoded, false, false);
    191 }
    192 
    193 std::string
    194 UrlEncodeStringForOnlyUnsafeChars(const std::string & decoded) {
    195   return InternalUrlEncodeString(decoded, false, true);
    196 }
    197