+/* -*-c-*-
+ *
+ * $Id: base64.c,v 1.1 1999/05/17 20:35:00 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.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: base64.c,v $
+ * Revision 1.1 1999/05/17 20:35:00 mdw
+ * Base64 encoding and decoding support.
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "base64.h"
+#include "dstr.h"
+
+/*----- Important tables --------------------------------------------------*/
+
+static const char base64_encodeMap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+ "abcdefghijklmnopqrstuvwxyz"
+ "0123456789+/" };
+
+static const signed char base64_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 unsigned char *src@ = 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 unsigned char *src, size_t sz,
+ dstr *d)
+{
+ if (src) {
+ unsigned long acc = ctx->acc;
+ unsigned qsz = ctx->qsz;
+
+ while (sz) {
+ acc = (acc << 8) | *src++;
+ qsz++;
+ sz--;
+ if (qsz == 3) {
+ dstr_putc(d, base64_encodeMap[(acc >> 18) & 0x3f]);
+ dstr_putc(d, base64_encodeMap[(acc >> 12) & 0x3f]);
+ dstr_putc(d, base64_encodeMap[(acc >> 6) & 0x3f]);
+ dstr_putc(d, base64_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;
+ dstr_putc(d, base64_encodeMap[(acc >> 18) & 0x3f]);
+ dstr_putc(d, base64_encodeMap[(acc >> 12) & 0x3f]);
+ dstr_putc(d, '=');
+ dstr_putc(d, '=');
+ ctx->lnlen += 4;
+ break;
+ case 2:
+ acc <<= 8;
+ dstr_putc(d, base64_encodeMap[(acc >> 18) & 0x3f]);
+ dstr_putc(d, base64_encodeMap[(acc >> 12) & 0x3f]);
+ dstr_putc(d, base64_encodeMap[(acc >> 6) & 0x3f]);
+ dstr_putc(d, '=');
+ ctx->lnlen += 4;
+ break;
+ }
+ ctx->qsz = 0;
+ ctx->acc = 0;
+ }
+}
+
+/* --- @base64_decode@ --- *
+ *
+ * Arguments: @base64_ctx *ctx@ = pointer to a context block
+ * @const unsigned char *src@ = 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 unsigned char *src, size_t sz,
+ dstr *d)
+{
+ if (src) {
+ unsigned long acc = ctx->acc;
+ unsigned qsz = ctx->qsz;
+ int ch;
+
+ while (sz) {
+
+ /* --- Get the next character and convert it --- */
+
+ ch = *src++;
+ if (ch >= 128 || ch < 0)
+ ch = -1;
+ else
+ ch = base64_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) {
+ dstr_putc(d, (acc >> 16) & 0xff);
+ dstr_putc(d, (acc >> 8) & 0xff);
+ dstr_putc(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 --- */
+
+ acc <<= 6 * (4 - qsz);
+ qsz *= 6;
+ while (qsz > 8) {
+ dstr_putc(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;
+ base64_ctx ctx;
+ void (*proc)(base64_ctx *, const unsigned char *, size_t, dstr *);
+ size_t sz;
+
+ dstr_create(&d);
+ 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 -------------------------------------------------*/
~mdw / mLib / commitdiff