[mLib] / base64.c

/* -*-c-*-
 *
 * $Id: base64.c,v 1.7 2004/04/08 01:36:11 mdw Exp $
 *
 * Base64 encoding and decoding.
 *
 * (c) 1997 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of the mLib utilities library.
 *
 * mLib is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * mLib 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 Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with mLib; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Header files ------------------------------------------------------*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "base64.h"
#include "dstr.h"

/*----- Important tables --------------------------------------------------*/

static const char encodemap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
				  "abcdefghijklmnopqrstuvwxyz" 
				  "0123456789+/" };

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

/*----- Main code ---------------------------------------------------------*/

/* --- @base64_encode@ --- *
 *
 * Arguments:	@base64_ctx *ctx@ = pointer to a context block
 *		@const void *p@ = pointer to a source buffer
 *		@size_t sz@ = size of the source buffer
 *		@dstr *d@ = pointer to destination string
 *
 * Returns:	---
 *
 * Use:		Encodes a binary string in base64.  To flush out the final
 *		few characters (if necessary), pass a null source pointer.
 */

void base64_encode(base64_ctx *ctx,
		   const void *p, size_t sz,
		   dstr *d)
{
  if (p) {
    unsigned long acc = ctx->acc;
    unsigned qsz = ctx->qsz;
    const unsigned char *src = p;

    while (sz) {
      acc = (acc << 8) | *src++;
      qsz++;
      sz--;
      if (qsz == 3) {
	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
	DPUTC(d, encodemap[(acc >>  6) & 0x3f]);
	DPUTC(d, encodemap[(acc >>  0) & 0x3f]);
	ctx->lnlen += 4;
	if (ctx->maxline && ctx->lnlen >= ctx->maxline) {
	  dstr_puts(d, ctx->indent);
	  ctx->lnlen = 0;
	}
	qsz = 0;
	acc = 0;
      }
    }

    ctx->acc = acc;
    ctx->qsz = qsz;
  } else {
    unsigned long acc = ctx->acc;
    unsigned qsz = ctx->qsz;

    switch (qsz) {
      case 0:
	break;
      case 1:
	acc <<= 16;
	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
	DPUTC(d, '=');
	DPUTC(d, '=');
	ctx->lnlen += 4;
	break;
      case 2:
	acc <<= 8;
	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
	DPUTC(d, encodemap[(acc >>  6) & 0x3f]);
	DPUTC(d, '=');
	ctx->lnlen += 4;
	break;
    }
    ctx->qsz = 0;
    ctx->acc = 0;
  }
}

/* --- @base64_decode@ --- *
 *
 * Arguments:	@base64_ctx *ctx@ = pointer to a context block
 *		@const void *p@ = pointer to a source buffer
 *		@size_t sz@ = size of the source buffer
 *		@dstr *d@ = pointer to destination string
 *
 * Returns:	---
 *
 * Use:		Decodes a binary string in base64.  To flush out the final
 *		few characters (if necessary), pass a null source pointer.
 */

void base64_decode(base64_ctx *ctx,
		   const void *p, size_t sz,
		   dstr *d)
{
  if (p) {
    unsigned long acc = ctx->acc;
    unsigned qsz = ctx->qsz;
    const char *src = p;
    int ch;

    while (sz) {

      /* --- Get the next character and convert it --- */

      ch = *src++;
      if (ch >= 128 || ch < 0)
	ch = -1;
      else
	ch = decodemap[ch];
      sz--;
      if (ch == -1)
	continue;

      /* --- Bung it in the accumulator --- */

      acc = (acc << 6) | ch;
      qsz++;

      /* --- Maybe write out a completed triplet --- */

      if (qsz == 4) {
	DPUTC(d, (acc >> 16) & 0xff);
	DPUTC(d, (acc >>  8) & 0xff);
	DPUTC(d, (acc >>  0) & 0xff);
	acc = 0;
	qsz = 0;
      }
    }

    ctx->acc = acc;
    ctx->qsz = qsz;
  } else {

    /* --- Notes about the tail-end bits --- *
     *
     * Ending Base64 decoding is messy.  The reference I'm using to define
     * the encoding, RFC1521 section 5.2, is a little hazy on exactly what to
     * do at the end.  It explains that I'm meant to ignore spurious `='
     * characters, and points out that I'm not guaranteed to see anything
     * interesting at the end.  I'll play safe here, and ignore all `='
     * characters, relying on my client to work out when to stop feeding me
     * data.  I'll use the queue size to work out how many tail-end bytes
     * I ought to write.
     */

    unsigned long acc = ctx->acc;
    unsigned qsz = ctx->qsz;

    /* --- Now fiddle with everything else --- *
     *
     * There's a bodge here for invalid encodings which have only one hextet
     * in the final group.  I'm not sure this is really worth having, but it
     * might save some unexpected behaviour.  (Not that you won't still get
     * unexpected behaviour if the stream is completely empty, of course.)
     */

    if (qsz) {
      acc <<= 6 * (4 - qsz);
      qsz *= 6;
      if (qsz < 8)
	qsz = 8;
      while (qsz >= 8) {
	DPUTC(d, (acc >> 16) & 0xff);
	acc <<= 8;
	qsz -= 8;
      }
    }

    /* --- That seems to be good enough --- */

    ctx->qsz = 0;
    ctx->acc = 0;
  }
}

/* --- @base64_init@ --- *
 *
 * Arguments:	@base64_ctx *ctx@ = pointer to context block to initialize
 *
 * Returns:	---
 *
 * Use:		Initializes a base64 context properly.
 */

void base64_init(base64_ctx *ctx)
{
  ctx->acc = 0;
  ctx->qsz = 0;
  ctx->lnlen = 0;
  ctx->indent = "\n";
  ctx->maxline = 72;
}

/*----- Test driver code --------------------------------------------------*/

#ifdef TEST_RIG

int main(int argc, char *argv[])
{
  unsigned char buf[BUFSIZ];
  dstr d = DSTR_INIT;
  base64_ctx ctx;
  void (*proc)(base64_ctx *, const void *, size_t, dstr *);
  size_t sz;

  base64_init(&ctx);

  if (argc > 1 && strcmp(argv[1], "-d") == 0)
    proc = base64_decode;
  else {
    proc = base64_encode;
    putchar('\t');
    ctx.indent = "\n\t";
    ctx.maxline = 64;
  }

  do {
    sz = fread(buf, 1, sizeof(buf), stdin);
    if (sz) {
      proc(&ctx, buf, sz, &d);
      dstr_write(&d, stdout);
      dstr_destroy(&d);
    }
  } while (sz == sizeof(buf));

  proc(&ctx, 0, 0, &d);
  dstr_write(&d, stdout);

  if (proc == base64_encode)
    putchar('\n');

  return (0);
}

#endif

/*----- That's all, folks -------------------------------------------------*/
Commit	Line	Data
ceba1986	1	/* --c--
ceba1986	2	*
8656dc50	3	* $Id: base64.c,v 1.7 2004/04/08 01:36:11 mdw Exp $
ceba1986	4	*
	5	* Base64 encoding and decoding.
	6	*
	7	* (c) 1997 Straylight/Edgeware
	8	*/
	9
	10	/----- Licensing notice --------------------------------------------------
	11	*
	12	* This file is part of the mLib utilities library.
	13	*
	14	* mLib is free software; you can redistribute it and/or modify
	15	* it under the terms of the GNU Library General Public License as
	16	* published by the Free Software Foundation; either version 2 of the
	17	* License, or (at your option) any later version.
	18	*
	19	* mLib is distributed in the hope that it will be useful,
	20	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	22	* GNU Library General Public License for more details.
	23	*
	24	* You should have received a copy of the GNU Library General Public
	25	* License along with mLib; if not, write to the Free
	26	* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
	27	* MA 02111-1307, USA.
	28	*/
	29
ceba1986	30	/----- Header files ------------------------------------------------------/
	31
	32	#include <stdio.h>
	33	#include <stdlib.h>
	34	#include <string.h>
	35
	36	#include "base64.h"
	37	#include "dstr.h"
	38
	39	/----- Important tables --------------------------------------------------/
	40
fde30071	41	static const char encodemap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	42	"abcdefghijklmnopqrstuvwxyz"
	43	"0123456789+/" };
ceba1986	44
fde30071	45	static const signed char decodemap[] = {
ceba1986	46	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */
	47	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */
	48	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 2x */
	49	52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 3x */
	50	-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 4x */
	51	15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 5x */
	52	-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 ,37, 38, 39, 40, /* 6x */
	53	41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 /* 7x */
	54	};
	55
	56	/----- Main code ---------------------------------------------------------/
	57
	58	/* --- @base64_encode@ --- *
	59	*
	60	* Arguments: @base64_ctx *ctx@ = pointer to a context block
c601c4f1	61	* @const void *p@ = pointer to a source buffer
ceba1986	62	* @size_t sz@ = size of the source buffer
	63	* @dstr *d@ = pointer to destination string
	64	*
	65	* Returns: ---
	66	*
	67	* Use: Encodes a binary string in base64. To flush out the final
	68	* few characters (if necessary), pass a null source pointer.
	69	*/
	70
	71	void base64_encode(base64_ctx *ctx,
c601c4f1	72	const void *p, size_t sz,
ceba1986	73	dstr *d)
ceba1986	74	{
c601c4f1	75	if (p) {
ceba1986	76	unsigned long acc = ctx->acc;
ceba1986	77	unsigned qsz = ctx->qsz;
c601c4f1	78	const unsigned char *src = p;
ceba1986	79
	80	while (sz) {
	81	acc = (acc << 8) \| *src++;
	82	qsz++;
	83	sz--;
	84	if (qsz == 3) {
fde30071	85	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
	86	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
	87	DPUTC(d, encodemap[(acc >> 6) & 0x3f]);
	88	DPUTC(d, encodemap[(acc >> 0) & 0x3f]);
ceba1986	89	ctx->lnlen += 4;
	90	if (ctx->maxline && ctx->lnlen >= ctx->maxline) {
	91	dstr_puts(d, ctx->indent);
	92	ctx->lnlen = 0;
	93	}
	94	qsz = 0;
	95	acc = 0;
	96	}
	97	}
	98
	99	ctx->acc = acc;
	100	ctx->qsz = qsz;
	101	} else {
	102	unsigned long acc = ctx->acc;
	103	unsigned qsz = ctx->qsz;
	104
	105	switch (qsz) {
	106	case 0:
	107	break;
	108	case 1:
	109	acc <<= 16;
fde30071	110	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
fde30071	111	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
c601c4f1	112	DPUTC(d, '=');
c601c4f1	113	DPUTC(d, '=');
ceba1986	114	ctx->lnlen += 4;
	115	break;
	116	case 2:
	117	acc <<= 8;
fde30071	118	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
	119	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
	120	DPUTC(d, encodemap[(acc >> 6) & 0x3f]);
c601c4f1	121	DPUTC(d, '=');
ceba1986	122	ctx->lnlen += 4;
	123	break;
	124	}
	125	ctx->qsz = 0;
	126	ctx->acc = 0;
	127	}
	128	}
	129
	130	/* --- @base64_decode@ --- *
	131	*
	132	* Arguments: @base64_ctx *ctx@ = pointer to a context block
c601c4f1	133	* @const void *p@ = pointer to a source buffer
ceba1986	134	* @size_t sz@ = size of the source buffer
	135	* @dstr *d@ = pointer to destination string
	136	*
	137	* Returns: ---
	138	*
	139	* Use: Decodes a binary string in base64. To flush out the final
	140	* few characters (if necessary), pass a null source pointer.
	141	*/
	142
	143	void base64_decode(base64_ctx *ctx,
c601c4f1	144	const void *p, size_t sz,
ceba1986	145	dstr *d)
ceba1986	146	{
c601c4f1	147	if (p) {
ceba1986	148	unsigned long acc = ctx->acc;
ceba1986	149	unsigned qsz = ctx->qsz;
c601c4f1	150	const char *src = p;
ceba1986	151	int ch;
	152
	153	while (sz) {
	154
	155	/* --- Get the next character and convert it --- */
	156
	157	ch = *src++;
	158	if (ch >= 128 \|\| ch < 0)
	159	ch = -1;
	160	else
fde30071	161	ch = decodemap[ch];
ceba1986	162	sz--;
	163	if (ch == -1)
	164	continue;
	165
	166	/* --- Bung it in the accumulator --- */
	167
	168	acc = (acc << 6) \| ch;
	169	qsz++;
	170
	171	/* --- Maybe write out a completed triplet --- */
	172
	173	if (qsz == 4) {
c601c4f1	174	DPUTC(d, (acc >> 16) & 0xff);
	175	DPUTC(d, (acc >> 8) & 0xff);
	176	DPUTC(d, (acc >> 0) & 0xff);
ceba1986	177	acc = 0;
	178	qsz = 0;
	179	}
	180	}
	181
	182	ctx->acc = acc;
	183	ctx->qsz = qsz;
	184	} else {
	185
	186	/* --- Notes about the tail-end bits --- *
	187	*
	188	* Ending Base64 decoding is messy. The reference I'm using to define
	189	* the encoding, RFC1521 section 5.2, is a little hazy on exactly what to
	190	* do at the end. It explains that I'm meant to ignore spurious `='
	191	* characters, and points out that I'm not guaranteed to see anything
	192	* interesting at the end. I'll play safe here, and ignore all `='
	193	* characters, relying on my client to work out when to stop feeding me
	194	* data. I'll use the queue size to work out how many tail-end bytes
	195	* I ought to write.
	196	*/
	197
	198	unsigned long acc = ctx->acc;
	199	unsigned qsz = ctx->qsz;
	200
a226592f	201	/* --- Now fiddle with everything else --- *
	202	*
	203	* There's a bodge here for invalid encodings which have only one hextet
	204	* in the final group. I'm not sure this is really worth having, but it
	205	* might save some unexpected behaviour. (Not that you won't still get
	206	* unexpected behaviour if the stream is completely empty, of course.)
	207	*/
ceba1986	208
a226592f	209	if (qsz) {
	210	acc <<= 6 * (4 - qsz);
	211	qsz *= 6;
	212	if (qsz < 8)
	213	qsz = 8;
	214	while (qsz >= 8) {
	215	DPUTC(d, (acc >> 16) & 0xff);
	216	acc <<= 8;
	217	qsz -= 8;
	218	}
ceba1986	219	}
	220
	221	/* --- That seems to be good enough --- */
	222
	223	ctx->qsz = 0;
	224	ctx->acc = 0;
	225	}
	226	}
	227
	228	/* --- @base64_init@ --- *
	229	*
	230	* Arguments: @base64_ctx *ctx@ = pointer to context block to initialize
	231	*
	232	* Returns: ---
	233	*
	234	* Use: Initializes a base64 context properly.
	235	*/
	236
	237	void base64_init(base64_ctx *ctx)
	238	{
	239	ctx->acc = 0;
	240	ctx->qsz = 0;
	241	ctx->lnlen = 0;
	242	ctx->indent = "\n";
	243	ctx->maxline = 72;
	244	}
	245
	246	/----- Test driver code --------------------------------------------------/
	247
	248	#ifdef TEST_RIG
	249
	250	int main(int argc, char *argv[])
	251	{
	252	unsigned char buf[BUFSIZ];
0bfb1431	253	dstr d = DSTR_INIT;
ceba1986	254	base64_ctx ctx;
d5679ed0	255	void (proc)(base64_ctx , const void , size_t, dstr );
ceba1986	256	size_t sz;
ceba1986	257
ceba1986	258	base64_init(&ctx);
	259
	260	if (argc > 1 && strcmp(argv[1], "-d") == 0)
	261	proc = base64_decode;
	262	else {
	263	proc = base64_encode;
	264	putchar('\t');
	265	ctx.indent = "\n\t";
	266	ctx.maxline = 64;
	267	}
	268
	269	do {
	270	sz = fread(buf, 1, sizeof(buf), stdin);
	271	if (sz) {
	272	proc(&ctx, buf, sz, &d);
	273	dstr_write(&d, stdout);
	274	dstr_destroy(&d);
	275	}
	276	} while (sz == sizeof(buf));
	277
	278	proc(&ctx, 0, 0, &d);
	279	dstr_write(&d, stdout);
	280
	281	if (proc == base64_encode)
	282	putchar('\n');
	283
	284	return (0);
	285	}
	286
	287	#endif
	288
	289	/----- That's all, folks -------------------------------------------------/