base64.c File Reference

Conversion to/from base64 encoding. More...

#include "config.h"
#include "base64.h"
#include "buffer.h"
#include "memory.h"
#include "string2.h"

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Macros
#define	BAD   -1

Functions
static size_t	b64_encode (const char *in, size_t inlen, char *out, size_t outlen, const char *alpha)
	Convert raw bytes to NUL-terminated base64 string.
size_t	mutt_b64_encode (const char *in, size_t inlen, char *out, size_t outlen)
	Convert raw bytes to a base64 string.
size_t	mutt_b64_encode_urlsafe (const char *in, size_t inlen, char *out, size_t outlen)
	Convert raw bytes to a URL-safe base64 string.
int	mutt_b64_decode (const char *in, char *out, size_t olen)
	Convert NUL-terminated base64 string to raw bytes.
size_t	mutt_b64_buffer_encode (struct Buffer *buf, const char *in, size_t len)
	Convert raw bytes to NUL-terminated base64 string.
int	mutt_b64_buffer_decode (struct Buffer *buf, const char *in)
	Convert NUL-terminated base64 string to raw bytes.

Variables
static const char	B64Chars [64]
	Characters of the Base64 encoding.
static const char	B64CharsUrlSafe [64]
	URL-Safe Characters of the Base64 encoding.
const int	Index64 [128]
	Lookup table for Base64 encoding characters.

Detailed Description

Conversion to/from base64 encoding.

Authors

• Richard Russon
• Pietro Cerutti

Copyright

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Definition in file base64.c.

Macro Definition Documentation

BAD

#define BAD   -1

Definition at line 39 of file base64.c.

Function Documentation

b64_encode()

static size_t b64_encode ( const char * in, size_t inlen, char * out, size_t outlen, const char * alpha )

static

Convert raw bytes to NUL-terminated base64 string.

Parameters

in	Input buffer for the raw bytes
inlen	Length of the input buffer
out	Output buffer for the base64 encoded string
outlen	Length of the output buffer
alpha	Alphabet to encode with

Return values

num	Length of the string written to the output buffer

This function performs base64 encoding. The resulting string is guaranteed to be NUL-terminated. The number of characters up to the terminating NUL-byte is returned (equivalent to calling strlen() on the output buffer after this function returns).

Definition at line 101 of file base64.c.

{
  if (!in || !out)
    return 0;
 
  unsigned char *begin = (unsigned char *) out;
  const unsigned char *inu = (const unsigned char *) in;
 
  while ((inlen >= 3) && (outlen > 4))
  {
    *out++ = alpha[inu[0] >> 2];
    *out++ = alpha[((inu[0] << 4) & 0x30) | (inu[1] >> 4)];
    *out++ = alpha[((inu[1] << 2) & 0x3c) | (inu[2] >> 6)];
    *out++ = alpha[inu[2] & 0x3f];
    outlen -= 4;
    inlen -= 3;
    inu += 3;
  }
 
  /* clean up remainder */
  if ((inlen > 0) && (outlen > 4))
  {
    unsigned char fragment;
 
    *out++ = alpha[inu[0] >> 2];
    fragment = (inu[0] << 4) & 0x30;
    if (inlen > 1)
      fragment |= inu[1] >> 4;
    *out++ = alpha[fragment];
    *out++ = (inlen < 2) ? '=' : alpha[(inu[1] << 2) & 0x3c];
    *out++ = '=';
  }
  *out = '\0';
  return out - (char *) begin;
}

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mutt_b64_encode()

size_t mutt_b64_encode	(	const char *	in,
		size_t	inlen,
		char *	out,
		size_t	outlen )

Convert raw bytes to a base64 string.

Parameters

in	Input buffer for the raw bytes
inlen	Length of the input buffer
out	Output buffer for the base64 encoded string
outlen	Length of the output buffer

Return values

num	Length of the string written to the output buffer

See also

b64_encode()

Definition at line 148 of file base64.c.

{
  return b64_encode(in, inlen, out, outlen, B64Chars);
}

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mutt_b64_encode_urlsafe()

size_t mutt_b64_encode_urlsafe	(	const char *	in,
		size_t	inlen,
		char *	out,
		size_t	outlen )

Convert raw bytes to a URL-safe base64 string.

Parameters

in	Input buffer for the raw bytes
inlen	Length of the input buffer
out	Output buffer for the base64 encoded string
outlen	Length of the output buffer

Return values

num	Length of the string written to the output buffer

See also

b64_encode()

Definition at line 163 of file base64.c.

{
  return b64_encode(in, inlen, out, outlen, B64CharsUrlSafe);
}

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mutt_b64_decode()

int mutt_b64_decode	(	const char *	in,
		char *	out,
		size_t	olen )

Convert NUL-terminated base64 string to raw bytes.

Parameters

in	Input buffer for the NUL-terminated base64-encoded string
out	Output buffer for the raw bytes
olen	Length of the output buffer

Return values

num	Success, bytes written
-1	Error

This function performs base64 decoding. The resulting buffer is NOT NUL-terminated. If the input buffer contains invalid base64 characters, this function returns -1.

Definition at line 180 of file base64.c.

{
  if (!in || !*in || !out)
    return -1;
 
  int len = 0;
 
  for (; *in; in += 4)
  {
    const unsigned char digit1 = in[0];
    if ((digit1 > 127) || (base64val(digit1) == BAD))
      return -1;
    const unsigned char digit2 = in[1];
    if ((digit2 > 127) || (base64val(digit2) == BAD))
      return -1;
 
    /* The 3rd and 4th bytes can be terminating padding chars ('='). Some
     * mailers don't properly terminate base64-encoded strings, so we allow for
     * the input string to terminate without padding. */
    const unsigned char digit3 = in[2] ? in[2] : '=';
    if ((digit3 > 127) || ((digit3 != '=') && (base64val(digit3) == BAD)))
      return -1;
    const unsigned char digit4 = (digit3 == '=') ? '=' : in[3];
    if ((digit4 > 127) || ((digit4 != '=') && (base64val(digit4) == BAD)))
      return -1;
 
    /* digits are already sanity-checked */
    if (len == olen)
      return len;
    *out++ = (base64val(digit1) << 2) | (base64val(digit2) >> 4);
    len++;
    if (digit3 != '=')
    {
      if (len == olen)
        return len;
      *out++ = ((base64val(digit2) << 4) & 0xf0) | (base64val(digit3) >> 2);
      len++;
      if (digit4 != '=')
      {
        if (len == olen)
          return len;
        *out++ = ((base64val(digit3) << 6) & 0xc0) | base64val(digit4);
        len++;
      }
    }
 
    /* did we reach the end? */
    if (digit4 == '=')
    {
      break;
    }
  }
 
  return len;
}

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mutt_b64_buffer_encode()

size_t mutt_b64_buffer_encode	(	struct Buffer *	buf,
		const char *	in,
		size_t	len )

Convert raw bytes to NUL-terminated base64 string.

Parameters

buf	Buffer for the result
in	Input buffer for the raw bytes
len	Length of the input buffer

Return values

num	Length of the string written to the output buffer

Definition at line 243 of file base64.c.

{
  if (!buf)
    return 0;
 
  buf_alloc(buf, MAX((len * 2), 1024));
  size_t num = mutt_b64_encode(in, len, buf->data, buf->dsize);
  buf_fix_dptr(buf);
  return num;
}

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mutt_b64_buffer_decode()

int mutt_b64_buffer_decode	(	struct Buffer *	buf,
		const char *	in )

Convert NUL-terminated base64 string to raw bytes.

Parameters

buf	Buffer for the result
in	Input buffer for the NUL-terminated base64-encoded string

Return values

num	Success, bytes written
-1	Error

Definition at line 261 of file base64.c.

{
  if (!buf)
    return -1;
 
  buf_alloc(buf, mutt_str_len(in));
  int olen = mutt_b64_decode(in, buf->data, buf->dsize);
  // mutt_b64_decode returns raw bytes, so don't terminate the buffer either
  if (olen > 0)
    buf_seek(buf, olen);
  else
    buf_seek(buf, 0);
 
  return olen;
}

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Variable Documentation

B64Chars

const char B64Chars[64]

static

Initial value:

= {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
  'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
  'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
  'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',
}

Characters of the Base64 encoding.

Definition at line 44 of file base64.c.

                                 {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
  'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
  'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
  'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',
};

B64CharsUrlSafe

const char B64CharsUrlSafe[64]

static

Initial value:

= {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
  'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
  'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
  'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
}

URL-Safe Characters of the Base64 encoding.

RFC4648 section 5 Base 64 Encoding with URL and Filename Safe Alphabet

Definition at line 57 of file base64.c.

                                        {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
  'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
  'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
  'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
};

Index64

const int Index64[128]

Initial value:

= {
  
  -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
  -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
  -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
  52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1,
  -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,
  15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
  -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
  41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
  
}

Lookup table for Base64 encoding characters.

Note

This is very similar to the table in imap/utf7.c

Encoding chars:

• utf7 A-Za-z0-9+,
• mime A-Za-z0-9+/

Definition at line 74 of file base64.c.

                         {
  // clang-format off
  -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
  -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
  -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
  52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1,
  -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,
  15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
  -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
  41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
  // clang-format on
};