modp_b64/modp_b64.h

   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 */