1 files changed, 55 insertions, 20 deletions

diff --git a/src/org/gnunet/util/Strings.java b/src/org/gnunet/util/Strings.java
index 3c369b1..a35568a 100644
--- a/src/org/gnunet/util/Strings.java
+++ b/src/org/gnunet/util/Strings.java
@@ -26,6 +26,21 @@ package org.gnunet.util;
 public class Strings {
     private static final String encTable = "0123456789ABCDEFGHIJKLMNOPQRSTUV";
 
+
+    /**
+     * Convert binary data to ASCII encoding.  The ASCII encoding is rather
+     * GNUnet specific.  It was chosen such that it only uses characters
+     * in [0-9A-V], can be produced without complex arithmetics and uses a
+     * small number of characters.
+     * Does not append 0-terminator, but returns a pointer to the place where
+     * it should be placed, if needed.
+     *
+     * returned string has length ((size*8) + (((size*8) % 5) > 0 ? 5 - ((size*8) % 5) : 0)) / 5 bytes
+     *
+     * @param data data to encode
+     * @return pointer to the next byte in 'out' or NULL on error.
+     */
+
     public static String dataToString(byte[] data) {
         StringBuilder sb = new StringBuilder();
 
@@ -54,15 +69,25 @@ public class Strings {
         return sb.toString();
     }
 
-    public static byte[] stringToData(String string) {
-        /*
+    /**
+     * Convert ASCII encoding back to data
+     * out_size must match exactly the size of the data before it was encoded.
+     *
+     * @param string the string to decode
+     * @param outSize size of the output buffer
+     * @return GNUNET_OK on success, GNUNET_SYSERR if result has the wrong encoding
+     */
+
+    public static byte[] stringToData(String string, int outSize) {
         long rpos;
         long wpos;
         long bits;
         long vbit;
-        int ret;
-        int shift;
-        int encoded_len = out_size * 8;
+        long ret;
+        long shift;
+        int enclen = string.length();
+        int encoded_len = outSize * 8;
+        byte[] out = new byte[outSize];
         if (encoded_len % 5 > 0) {
             // padding!
             vbit = encoded_len % 5;
@@ -75,29 +100,39 @@ public class Strings {
             throw new AssertionError();
         }
 
-        wpos = out_size;
+        wpos = outSize;
         rpos = enclen;
-        bits = (ret = getValue__(enc[--rpos])) >> (5 - encoded_len % 5);
-        if (-1 == ret)
-            return GNUNET_SYSERR;
+        bits = (ret = getValue__(string.charAt((int) (--rpos)))) >> (5 - encoded_len % 5);
+        if (-1 == ret) {
+            throw new AssertionError();
+        }
         while (wpos > 0) {
-            GNUNET_assert(rpos > 0);
-            bits = ((ret = getValue__(enc[--rpos])) << vbit) | bits;
-            if (-1 == ret)
-                return GNUNET_SYSERR;
+            assert rpos > 0;
+            bits = ((ret = getValue__(string.charAt((int) (--rpos)))) << vbit) | bits;
+            if (-1 == ret) {
+                throw new AssertionError();
+            }
             vbit += 5;
             if (vbit >= 8) {
-                out[--wpos] = (unsigned char)bits;
+                out[(int)--wpos] = (byte)((char) bits);
                 bits >>= 8;
                 vbit -= 8;
             }
         }
-        GNUNET_assert(rpos == 0);
-        GNUNET_assert(vbit == 0);
-        return GNUNET_OK;
-
+        assert(rpos == 0);
+        assert(vbit == 0);
+        return out;
     }
-    */
-    throw new UnsupportedOperationException("not yet implemented");
+
+
+    private static int getValue__ (char a) {
+        if ((a >= '0') && (a <= '9')) {
+            return a - '0';
+        }
+        if ((a >= 'A') && (a <= 'V')) {
+            return (a - 'A' + 10);
+        }
+        return -1;
     }
+
 }