X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/fce810c27ad09dd73706100435a6e65af0a67604..e18c4734744e56b738ca2918dffe071f95f4c14b:/lib/base64.c

diff --git a/lib/base64.c b/lib/base64.c
index 8015b1a..7909b4f 100644
--- a/lib/base64.c
+++ b/lib/base64.c
@@ -1,6 +1,6 @@
 /*
  * This file is part of DisOrder
- * Copyright (C) 2005, 2007 Richard Kettlewell
+ * Copyright (C) 2005, 2007, 2008 Richard Kettlewell
  *
  * 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
@@ -33,13 +33,31 @@
 #include "vector.h"
 
 static const char mime_base64_table[] =
-  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
 
 /** @brief Convert MIME base64
  * @param s base64 data
+ * @param nsp Where to store length of converted data
  * @return Decoded data
+ *
+ * See <a href="http://tools.ietf.org/html/rfc2045#section-6.8">RFC
+ * 2045 s6.8</a>.
  */
 char *mime_base64(const char *s, size_t *nsp) {
+  return generic_base64(s, nsp, mime_base64_table);
+}
+
+/** @brief Convert base64
+ * @param s base64 data
+ * @param nsp Where to store length of converted data
+ * @param table Table of characters to use
+ * @return Decoded data
+ *
+ * @p table should consist of 65 characters.  The first 64 will be used to
+ * represents the 64 digits and the 65th will be used as padding at the end
+ * (i.e. the role of '=' in RFC2045 base64).
+ */
+char *generic_base64(const char *s, size_t *nsp, const char *table) {
   struct dynstr d;
   const char *t;
   int b[4], n, c;
@@ -47,21 +65,21 @@ char *mime_base64(const char *s, size_t *nsp) {
   dynstr_init(&d);
   n = 0;
   while((c = (unsigned char)*s++)) {
-    if((t = strchr(mime_base64_table, c))) {
-      b[n++] = t - mime_base64_table;
-      if(n == 4) {
-	dynstr_append(&d, (b[0] << 2) + (b[1] >> 4));
-	dynstr_append(&d, (b[1] << 4) + (b[2] >> 2));
-	dynstr_append(&d, (b[2] << 6) + b[3]);
-	n = 0;
-      }
-    } else if(c == '=') {
+    if(c == table[64]) {
       if(n >= 2) {
 	dynstr_append(&d, (b[0] << 2) + (b[1] >> 4));
 	if(n == 3)
 	  dynstr_append(&d, (b[1] << 4) + (b[2] >> 2));
       }
       break;
+    } else if((t = strchr(table, c))) {
+      b[n++] = t - table;
+      if(n == 4) {
+	dynstr_append(&d, (b[0] << 2) + (b[1] >> 4));
+	dynstr_append(&d, (b[1] << 4) + (b[2] >> 2));
+	dynstr_append(&d, (b[2] << 6) + b[3]);
+	n = 0;
+      }
     }
   }
   if(nsp)
@@ -70,42 +88,61 @@ char *mime_base64(const char *s, size_t *nsp) {
   return d.vec;
 }
 
-/** @brief Convert a binary string to base64
+/** @brief Convert a binary string to MIME base64
  * @param s Bytes to convert
  * @param ns Number of bytes to convert
  * @return Encoded data
  *
  * This function does not attempt to split up lines.
+ *
+ * See <a href="http://tools.ietf.org/html/rfc2045#section-6.8">RFC
+ * 2045 s6.8</a>.
  */
 char *mime_to_base64(const uint8_t *s, size_t ns) {
+  return generic_to_base64(s, ns, mime_base64_table);
+}
+
+/** @brief Convert a binary string to base64
+ * @param s Bytes to convert
+ * @param ns Number of bytes to convert
+ * @param table Table of characters to use
+ * @return Encoded data
+ *
+ * This function does not attempt to split up lines.
+ *
+ * @p table should consist of 65 characters.  The first 64 will be used to
+ * represents the 64 digits and the 65th will be used as padding at the end
+ * (i.e. the role of '=' in RFC2045 base64).
+ */
+char *generic_to_base64(const uint8_t *s, size_t ns, const char *table) {
   struct dynstr d[1];
 
   dynstr_init(d);
   while(ns >= 3) {
     /* Input bytes with output bits: AAAAAABB BBBBCCCC CCDDDDDD */
     /* Output bytes with input bits: 000000 001111 111122 222222 */
-    dynstr_append(d, mime_base64_table[s[0] >> 2]);
-    dynstr_append(d, mime_base64_table[((s[0] & 3) << 4)
+    dynstr_append(d, table[s[0] >> 2]);
+    dynstr_append(d, table[((s[0] & 3) << 4)
 				       + (s[1] >> 4)]);
-    dynstr_append(d, mime_base64_table[((s[1] & 15) << 2)
+    dynstr_append(d, table[((s[1] & 15) << 2)
 				       + (s[2] >> 6)]);
-    dynstr_append(d, mime_base64_table[s[2] & 63]);
+    dynstr_append(d, table[s[2] & 63]);
     ns -= 3;
     s += 3;
   }
   if(ns > 0) {
-    dynstr_append(d, mime_base64_table[s[0] >> 2]);
+    dynstr_append(d, table[s[0] >> 2]);
     switch(ns) {
     case 1:
-      dynstr_append(d, mime_base64_table[(s[0] & 3) << 4]);
-      dynstr_append(d, '=');
-      dynstr_append(d, '=');
+      dynstr_append(d, table[(s[0] & 3) << 4]);
+      dynstr_append(d, table[64]);
+      dynstr_append(d, table[64]);
       break;
     case 2:
-      dynstr_append(d, mime_base64_table[((s[0] & 3) << 4)
+      dynstr_append(d, table[((s[0] & 3) << 4)
 					 + (s[1] >> 4)]);
-      dynstr_append(d, mime_base64_table[(s[1] & 15) << 2]);
-      dynstr_append(d, '=');
+      dynstr_append(d, table[(s[1] & 15) << 2]);
+      dynstr_append(d, table[64]);
       break;
     }
   }