[mLib] / base64.c

/* -*-c-*-
 *
 * 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	*
	3	* Base64 encoding and decoding.
	4	*
	5	* (c) 1997 Straylight/Edgeware
	6	*/
	7
d4efbcd9	8	/----- Licensing notice --------------------------------------------------
ceba1986	9	*
	10	* This file is part of the mLib utilities library.
	11	*
	12	* mLib is free software; you can redistribute it and/or modify
	13	* it under the terms of the GNU Library General Public License as
	14	* published by the Free Software Foundation; either version 2 of the
	15	* License, or (at your option) any later version.
d4efbcd9	16	*
ceba1986	17	* mLib is distributed in the hope that it will be useful,
	18	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	20	* GNU Library General Public License for more details.
d4efbcd9	21	*
ceba1986	22	* You should have received a copy of the GNU Library General Public
	23	* License along with mLib; if not, write to the Free
	24	* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
	25	* MA 02111-1307, USA.
	26	*/
	27
ceba1986	28	/----- Header files ------------------------------------------------------/
	29
	30	#include <stdio.h>
	31	#include <stdlib.h>
	32	#include <string.h>
	33
	34	#include "base64.h"
	35	#include "dstr.h"
	36
	37	/----- Important tables --------------------------------------------------/
	38
fde30071	39	static const char encodemap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
d4efbcd9	40	"abcdefghijklmnopqrstuvwxyz"
fde30071	41	"0123456789+/" };
ceba1986	42
fde30071	43	static const signed char decodemap[] = {
ceba1986	44	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */
	45	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */
	46	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 2x */
	47	52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 3x */
	48	-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 4x */
	49	15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 5x */
	50	-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 ,37, 38, 39, 40, /* 6x */
	51	41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 /* 7x */
d4efbcd9	52	};
ceba1986	53
	54	/----- Main code ---------------------------------------------------------/
	55
	56	/* --- @base64_encode@ --- *
	57	*
	58	* Arguments: @base64_ctx *ctx@ = pointer to a context block
c601c4f1	59	* @const void *p@ = pointer to a source buffer
ceba1986	60	* @size_t sz@ = size of the source buffer
	61	* @dstr *d@ = pointer to destination string
	62	*
	63	* Returns: ---
	64	*
	65	* Use: Encodes a binary string in base64. To flush out the final
	66	* few characters (if necessary), pass a null source pointer.
	67	*/
	68
	69	void base64_encode(base64_ctx *ctx,
c601c4f1	70	const void *p, size_t sz,
ceba1986	71	dstr *d)
ceba1986	72	{
c601c4f1	73	if (p) {
ceba1986	74	unsigned long acc = ctx->acc;
ceba1986	75	unsigned qsz = ctx->qsz;
c601c4f1	76	const unsigned char *src = p;
ceba1986	77
	78	while (sz) {
	79	acc = (acc << 8) \| *src++;
	80	qsz++;
	81	sz--;
	82	if (qsz == 3) {
fde30071	83	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
	84	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
	85	DPUTC(d, encodemap[(acc >> 6) & 0x3f]);
	86	DPUTC(d, encodemap[(acc >> 0) & 0x3f]);
ceba1986	87	ctx->lnlen += 4;
	88	if (ctx->maxline && ctx->lnlen >= ctx->maxline) {
	89	dstr_puts(d, ctx->indent);
	90	ctx->lnlen = 0;
	91	}
	92	qsz = 0;
	93	acc = 0;
	94	}
	95	}
	96
	97	ctx->acc = acc;
	98	ctx->qsz = qsz;
	99	} else {
	100	unsigned long acc = ctx->acc;
	101	unsigned qsz = ctx->qsz;
	102
	103	switch (qsz) {
	104	case 0:
	105	break;
	106	case 1:
	107	acc <<= 16;
fde30071	108	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
fde30071	109	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
c601c4f1	110	DPUTC(d, '=');
c601c4f1	111	DPUTC(d, '=');
ceba1986	112	ctx->lnlen += 4;
	113	break;
	114	case 2:
	115	acc <<= 8;
fde30071	116	DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
	117	DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
	118	DPUTC(d, encodemap[(acc >> 6) & 0x3f]);
c601c4f1	119	DPUTC(d, '=');
ceba1986	120	ctx->lnlen += 4;
	121	break;
	122	}
	123	ctx->qsz = 0;
	124	ctx->acc = 0;
	125	}
	126	}
	127
	128	/* --- @base64_decode@ --- *
	129	*
	130	* Arguments: @base64_ctx *ctx@ = pointer to a context block
c601c4f1	131	* @const void *p@ = pointer to a source buffer
ceba1986	132	* @size_t sz@ = size of the source buffer
	133	* @dstr *d@ = pointer to destination string
	134	*
	135	* Returns: ---
	136	*
	137	* Use: Decodes a binary string in base64. To flush out the final
	138	* few characters (if necessary), pass a null source pointer.
	139	*/
	140
	141	void base64_decode(base64_ctx *ctx,
c601c4f1	142	const void *p, size_t sz,
ceba1986	143	dstr *d)
ceba1986	144	{
c601c4f1	145	if (p) {
ceba1986	146	unsigned long acc = ctx->acc;
ceba1986	147	unsigned qsz = ctx->qsz;
c601c4f1	148	const char *src = p;
ceba1986	149	int ch;
	150
	151	while (sz) {
	152
	153	/* --- Get the next character and convert it --- */
	154
	155	ch = *src++;
	156	if (ch >= 128 \|\| ch < 0)
	157	ch = -1;
	158	else
fde30071	159	ch = decodemap[ch];
ceba1986	160	sz--;
	161	if (ch == -1)
	162	continue;
	163
	164	/* --- Bung it in the accumulator --- */
	165
	166	acc = (acc << 6) \| ch;
	167	qsz++;
	168
	169	/* --- Maybe write out a completed triplet --- */
	170
	171	if (qsz == 4) {
c601c4f1	172	DPUTC(d, (acc >> 16) & 0xff);
	173	DPUTC(d, (acc >> 8) & 0xff);
	174	DPUTC(d, (acc >> 0) & 0xff);
ceba1986	175	acc = 0;
	176	qsz = 0;
	177	}
	178	}
	179
	180	ctx->acc = acc;
	181	ctx->qsz = qsz;
	182	} else {
	183
	184	/* --- Notes about the tail-end bits --- *
	185	*
	186	* Ending Base64 decoding is messy. The reference I'm using to define
	187	* the encoding, RFC1521 section 5.2, is a little hazy on exactly what to
	188	* do at the end. It explains that I'm meant to ignore spurious `='
	189	* characters, and points out that I'm not guaranteed to see anything
	190	* interesting at the end. I'll play safe here, and ignore all `='
	191	* characters, relying on my client to work out when to stop feeding me
	192	* data. I'll use the queue size to work out how many tail-end bytes
	193	* I ought to write.
	194	*/
	195
	196	unsigned long acc = ctx->acc;
	197	unsigned qsz = ctx->qsz;
	198
a226592f	199	/* --- Now fiddle with everything else --- *
	200	*
	201	* There's a bodge here for invalid encodings which have only one hextet
	202	* in the final group. I'm not sure this is really worth having, but it
	203	* might save some unexpected behaviour. (Not that you won't still get
	204	* unexpected behaviour if the stream is completely empty, of course.)
	205	*/
ceba1986	206
a226592f	207	if (qsz) {
	208	acc <<= 6 * (4 - qsz);
	209	qsz *= 6;
	210	if (qsz < 8)
	211	qsz = 8;
	212	while (qsz >= 8) {
	213	DPUTC(d, (acc >> 16) & 0xff);
	214	acc <<= 8;
	215	qsz -= 8;
	216	}
ceba1986	217	}
	218
	219	/* --- That seems to be good enough --- */
	220
	221	ctx->qsz = 0;
	222	ctx->acc = 0;
	223	}
	224	}
	225
	226	/* --- @base64_init@ --- *
	227	*
	228	* Arguments: @base64_ctx *ctx@ = pointer to context block to initialize
	229	*
	230	* Returns: ---
	231	*
	232	* Use: Initializes a base64 context properly.
	233	*/
	234
	235	void base64_init(base64_ctx *ctx)
	236	{
	237	ctx->acc = 0;
	238	ctx->qsz = 0;
	239	ctx->lnlen = 0;
	240	ctx->indent = "\n";
	241	ctx->maxline = 72;
	242	}
	243
	244	/----- Test driver code --------------------------------------------------/
	245
	246	#ifdef TEST_RIG
	247
	248	int main(int argc, char *argv[])
	249	{
	250	unsigned char buf[BUFSIZ];
0bfb1431	251	dstr d = DSTR_INIT;
ceba1986	252	base64_ctx ctx;
d5679ed0	253	void (proc)(base64_ctx , const void , size_t, dstr );
ceba1986	254	size_t sz;
ceba1986	255
ceba1986	256	base64_init(&ctx);
	257
	258	if (argc > 1 && strcmp(argv[1], "-d") == 0)
	259	proc = base64_decode;
	260	else {
	261	proc = base64_encode;
	262	putchar('\t');
	263	ctx.indent = "\n\t";
	264	ctx.maxline = 64;
	265	}
	266
	267	do {
	268	sz = fread(buf, 1, sizeof(buf), stdin);
	269	if (sz) {
	270	proc(&ctx, buf, sz, &d);
	271	dstr_write(&d, stdout);
	272	dstr_destroy(&d);
	273	}
	274	} while (sz == sizeof(buf));
	275
	276	proc(&ctx, 0, 0, &d);
	277	dstr_write(&d, stdout);
	278
	279	if (proc == base64_encode)
	280	putchar('\n');
	281
	282	return (0);
	283	}
	284
	285	#endif
	286
	287	/----- That's all, folks -------------------------------------------------/