+/* -*-c-*-
+ *
+ * $Id$
+ *
+ * Base32 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 "base32.h"
+#include "dstr.h"
+
+/*----- Important tables --------------------------------------------------*/
+
+static const char encodemap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567" };
+
+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, -1, -1, -1, -1, -1, /* 2x */
+ -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -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, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 6x */
+ 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 7x */
+};
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @base32_encode@ --- *
+ *
+ * Arguments: @base32_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 base32. To flush out the final
+ * few characters (if necessary), pass a null source pointer.
+ */
+
+void base32_encode(base32_ctx *ctx,
+ const void *p, size_t sz,
+ dstr *d)
+{
+ if (p) {
+ unsigned long accl = ctx->accl, acch = ctx->acch;
+ unsigned qsz = ctx->qsz;
+ const unsigned char *src = p;
+
+ while (sz) {
+ acch = (acch << 8) | ((accl >> 24) & 0xff);
+ accl = (accl << 8) | *src++;
+ qsz++;
+ sz--;
+ if (qsz == 5) {
+ DPUTC(d, encodemap[(acch >> 3) & 0x1f]);
+ DPUTC(d, encodemap[((acch << 2) & 0x1c) | ((accl >> 30) & 0x03)]);
+ DPUTC(d, encodemap[(accl >> 25) & 0x1f]);
+ DPUTC(d, encodemap[(accl >> 20) & 0x1f]);
+ DPUTC(d, encodemap[(accl >> 15) & 0x1f]);
+ DPUTC(d, encodemap[(accl >> 10) & 0x1f]);
+ DPUTC(d, encodemap[(accl >> 5) & 0x1f]);
+ DPUTC(d, encodemap[(accl >> 0) & 0x1f]);
+ ctx->lnlen += 8;
+ if (ctx->maxline && ctx->lnlen >= ctx->maxline) {
+ dstr_puts(d, ctx->indent);
+ ctx->lnlen = 0;
+ }
+ qsz = 0;
+ accl = acch = 0;
+ }
+ }
+
+ ctx->acch = acch; ctx->accl = accl;
+ ctx->qsz = qsz;
+ } else {
+ unsigned long accl = ctx->accl, acch = ctx->acch;
+ unsigned qsz = ctx->qsz;
+
+ if (qsz) {
+ unsigned pad = 5 - qsz;
+ if (pad > 3) {
+ acch = accl << (pad * 8 - 32);
+ accl = 0;
+ } else {
+ acch = (acch << (8 * pad)) | ((accl & 0xffffffff) >> (32 - 8 * pad));
+ accl = accl << (8 * pad);
+ }
+ qsz = 40;
+ pad *= 8;
+ while (qsz > pad) {
+ DPUTC(d, encodemap[(acch >> 3) & 0x1f]);
+ acch = (acch << 5) | ((accl >> 27) & 0x1f);
+ accl = (accl << 5);
+ qsz -= 5;
+ }
+ while (qsz) {
+ DPUTC(d, '=');
+ qsz -= 5;
+ }
+ ctx->lnlen += 8;
+ }
+ ctx->qsz = 0;
+ ctx->acch = ctx->accl = 0;
+ }
+}
+
+/* --- @base32_decode@ --- *
+ *
+ * Arguments: @base32_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 base32. To flush out the final
+ * few characters (if necessary), pass a null source pointer.
+ */
+
+void base32_decode(base32_ctx *ctx,
+ const void *p, size_t sz,
+ dstr *d)
+{
+ if (p) {
+ unsigned long accl = ctx->accl, acch = ctx->acch;
+ 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 --- */
+
+ acch = (acch << 5) | ((accl >> 27) & 0x1f);
+ accl = (accl << 5) | ch;
+ qsz++;
+
+ /* --- Maybe write out a completed triplet --- */
+
+ if (qsz == 8) {
+ DPUTC(d, (acch >> 0) & 0xff);
+ DPUTC(d, (accl >> 24) & 0xff);
+ DPUTC(d, (accl >> 16) & 0xff);
+ DPUTC(d, (accl >> 8) & 0xff);
+ DPUTC(d, (accl >> 0) & 0xff);
+ acch = accl = 0;
+ qsz = 0;
+ }
+ }
+
+ ctx->acch = acch; ctx->accl = accl;
+ ctx->qsz = qsz;
+ } else {
+
+ /* --- Notes about the tail-end bits --- *
+ *
+ * I'll use the queue size to work out how many tail-end bytes I ought to
+ * write. This isn't strictly right, but it's easier.
+ */
+
+ unsigned long acch = ctx->acch, accl = ctx->accl;
+ unsigned qsz = ctx->qsz;
+
+ /* --- Now fiddle with everything else --- *
+ *
+ * There's a bodge here for invalid encodings which have a funny number
+ * of quintets 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) {
+ unsigned pad = 8 - qsz;
+ if (pad > 6) {
+ acch = accl << (5 * pad - 32);
+ accl = 0;
+ } else {
+ acch = (acch << (5 * pad)) | ((accl & 0xffffffff) >> (32 - 5 * pad));
+ accl = accl << (5 * pad);
+ }
+
+ qsz *= 5;
+ while (qsz >= 8) {
+ DPUTC(d, acch & 0xff);
+ acch = accl >> 24;
+ accl <<= 8;
+ qsz -= 8;
+ }
+ }
+
+ /* --- That seems to be good enough --- */
+
+ ctx->qsz = 0;
+ ctx->acch = ctx->accl = 0;
+ }
+}
+
+/* --- @base32_init@ --- *
+ *
+ * Arguments: @base32_ctx *ctx@ = pointer to context block to initialize
+ *
+ * Returns: ---
+ *
+ * Use: Initializes a base32 context properly.
+ */
+
+void base32_init(base32_ctx *ctx)
+{
+ ctx->accl = ctx->acch = 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;
+ base32_ctx ctx;
+ void (*proc)(base32_ctx *, const void *, size_t, dstr *);
+ size_t sz;
+
+ base32_init(&ctx);
+
+ if (argc > 1 && strcmp(argv[1], "-d") == 0)
+ proc = base32_decode;
+ else {
+ proc = base32_encode;
+ putchar('\t');
+ ctx.indent = "\n\t";
+ ctx.maxline = 32;
+ }
+
+ 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 == base32_encode)
+ putchar('\n');
+
+ return (0);
+}
+
+#endif
+
+/*----- That's all, folks -------------------------------------------------*/
~mdw / mLib / commitdiff