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      1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 4 -*- */
      2 /* vi: set expandtab shiftwidth=4 tabstop=4: */
      3 
      4 /**
      5  * \file
      6  * <PRE>
      7  * High performance base64 encoder / decoder
      8  * Version 1.3 -- 17-Mar-2006
      9  *
     10  * Copyright &copy; 2005, 2006, Nick Galbreath -- nickg [at] modp [dot] com
     11  * All rights reserved.
     12  *
     13  * http://modp.com/release/base64
     14  *
     15  * Released under bsd license.  See modp_b64.c for details.
     16  * </pre>
     17  *
     18  * The default implementation is the standard b64 encoding with padding.
     19  * It's easy to change this to use "URL safe" characters and to remove
     20  * padding.  See the modp_b64.c source code for details.
     21  *
     22  */
     23 
     24 #ifndef MODP_B64
     25 #define MODP_B64
     26 
     27 #ifdef __cplusplus
     28 extern "C" {
     29 #endif
     30 
     31 /**
     32  * Encode a raw binary string into base 64.
     33  * src contains the bytes
     34  * len contains the number of bytes in the src
     35  * dest should be allocated by the caller to contain
     36  *   at least modp_b64_encode_len(len) bytes (see below)
     37  *   This will contain the null-terminated b64 encoded result
     38  * returns length of the destination string plus the ending null byte
     39  *    i.e.  the result will be equal to strlen(dest) + 1
     40  *
     41  * Example
     42  *
     43  * \code
     44  * char* src = ...;
     45  * int srclen = ...; //the length of number of bytes in src
     46  * char* dest = (char*) malloc(modp_b64_encode_len);
     47  * int len = modp_b64_encode(dest, src, sourcelen);
     48  * if (len == -1) {
     49  *   printf("Error\n");
     50  * } else {
     51  *   printf("b64 = %s\n", dest);
     52  * }
     53  * \endcode
     54  *
     55  */
     56 int modp_b64_encode(char* dest, const char* str, int len);
     57 
     58 /**
     59  * Decode a base64 encoded string
     60  *
     61  * src should contain exactly len bytes of b64 characters.
     62  *     if src contains -any- non-base characters (such as white
     63  *     space, -1 is returned.
     64  *
     65  * dest should be allocated by the caller to contain at least
     66  *    len * 3 / 4 bytes.
     67  *
     68  * Returns the length (strlen) of the output, or -1 if unable to
     69  * decode
     70  *
     71  * \code
     72  * char* src = ...;
     73  * int srclen = ...; // or if you don't know use strlen(src)
     74  * char* dest = (char*) malloc(modp_b64_decode_len(srclen));
     75  * int len = modp_b64_decode(dest, src, sourcelen);
     76  * if (len == -1) { error }
     77  * \endcode
     78  */
     79 int modp_b64_decode(char* dest, const char* src, int len);
     80 
     81 /**
     82  * Given a source string of length len, this returns the amount of
     83  * memory the destination string should have.
     84  *
     85  * remember, this is integer math
     86  * 3 bytes turn into 4 chars
     87  * ceiling[len / 3] * 4 + 1
     88  *
     89  * +1 is for any extra null.
     90  */
     91 #define modp_b64_encode_len(A) ((A+2)/3 * 4 + 1)
     92 
     93 /**
     94  * Given a base64 string of length len,
     95  *   this returns the amount of memory required for output string
     96  *  It maybe be more than the actual number of bytes written.
     97  * NOTE: remember this is integer math
     98  * this allocates a bit more memory than traditional versions of b64
     99  * decode  4 chars turn into 3 bytes
    100  * floor[len * 3/4] + 2
    101  */
    102 #define modp_b64_decode_len(A) (A / 4 * 3 + 2)
    103 
    104 /**
    105  * Will return the strlen of the output from encoding.
    106  * This may be less than the required number of bytes allocated.
    107  *
    108  * This allows you to 'deserialized' a struct
    109  * \code
    110  * char* b64encoded = "...";
    111  * int len = strlen(b64encoded);
    112  *
    113  * struct datastuff foo;
    114  * if (modp_b64_encode_strlen(sizeof(struct datastuff)) != len) {
    115  *    // wrong size
    116  *    return false;
    117  * } else {
    118  *    // safe to do;
    119  *    if (modp_b64_decode((char*) &foo, b64encoded, len) == -1) {
    120  *      // bad characters
    121  *      return false;
    122  *    }
    123  * }
    124  * // foo is filled out now
    125  * \endcode
    126  */
    127 #define modp_b64_encode_strlen(A) ((A + 2)/ 3 * 4)
    128 
    129 #ifdef __cplusplus
    130 }
    131 
    132 #include <string>
    133 
    134 inline std::string& modp_b64_encode(std::string& s)
    135 {
    136     std::string x(modp_b64_encode_len(s.size()), '\0');
    137     int d = modp_b64_encode(const_cast<char*>(x.data()), s.data(), s.size());
    138     x.erase(d, std::string::npos);
    139     s.swap(x);
    140     return s;
    141 }
    142 
    143 /**
    144  * base 64 decode a string (self-modifing)
    145  * On failure, the string is empty.
    146  *
    147  * This function is for C++ only (duh)
    148  *
    149  * \param[in,out] s the string to be decoded
    150  * \return a reference to the input string
    151  */
    152 inline std::string& modp_b64_decode(std::string& s)
    153 {
    154     std::string x(modp_b64_decode_len(s.size()), '\0');
    155     int d = modp_b64_decode(const_cast<char*>(x.data()), s.data(), s.size());
    156     if (d < 0) {
    157         x.clear();
    158     } else {
    159         x.erase(d, std::string::npos);
    160     }
    161     s.swap(x);
    162     return s;
    163 }
    164 
    165 #endif /* __cplusplus */
    166 
    167 #endif /* MODP_B64 */
    168