X-Git-Url: https://git.pterodactylus.net/?p=jFCPlib.git;a=blobdiff_plain;f=src%2Fmain%2Fjava%2Fnet%2Fpterodactylus%2Ffcp%2FFreenetBase64.java;fp=src%2Fmain%2Fjava%2Fnet%2Fpterodactylus%2Ffcp%2FFreenetBase64.java;h=4c3422d060904046c1872871464c6161585c234d;hp=0000000000000000000000000000000000000000;hb=fed333217dc45a47f6eabea6a5b29aed987cd160;hpb=6065356598b699145344a1a873054f2e5b0d23ef

diff --git a/src/main/java/net/pterodactylus/fcp/FreenetBase64.java b/src/main/java/net/pterodactylus/fcp/FreenetBase64.java
new file mode 100644
index 0000000..4c3422d
--- /dev/null
+++ b/src/main/java/net/pterodactylus/fcp/FreenetBase64.java
@@ -0,0 +1,90 @@
+package net.pterodactylus.fcp;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+/**
+ * Freenet-specific Base64 implementation.
+ *
+ * @author <a href="mailto:bombe@freenetproject.org">David ‘Bombe’ Roden</a>
+ */
+public class FreenetBase64 {
+
+	private static final char[] FREENET_BASE64_ALPHABET =
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789~-".toCharArray();
+	private static final int[] REVERSE_FREENET_BASE64_ALPHABET = reverse(FREENET_BASE64_ALPHABET);
+
+	private static int[] reverse(char[] alphabet) {
+		String alphabetString = new String(alphabet);
+		int[] reversedAlphabet = new int[128];
+		for (int i = 0; i < 128; i++) {
+			if (alphabetString.indexOf(i) > -1) {
+				reversedAlphabet[i] = alphabetString.indexOf(i);
+			} else {
+				reversedAlphabet[i] = -1;
+			}
+		}
+		return reversedAlphabet;
+	}
+
+	public String encode(byte[] data) {
+		StringBuilder result = new StringBuilder();
+		int currentValue = 0;
+		int index = 0;
+		while (index < data.length) {
+			currentValue = (currentValue << 8) | data[index];
+			if (index % 3 == 2) {
+				result.append(FREENET_BASE64_ALPHABET[(currentValue >> 18) & 0x3f]);
+				result.append(FREENET_BASE64_ALPHABET[(currentValue >> 12) & 0x3f]);
+				result.append(FREENET_BASE64_ALPHABET[(currentValue >> 6) & 0x3f]);
+				result.append(FREENET_BASE64_ALPHABET[currentValue & 0x3f]);
+			}
+			index++;
+		}
+		if (index % 3 == 1) {
+			result.append(FREENET_BASE64_ALPHABET[(currentValue >> 2) & 0x3f]);
+			result.append(FREENET_BASE64_ALPHABET[(currentValue << 4) & 0x3f]);
+			result.append("==");
+		} else if (index % 3 == 2) {
+			result.append(FREENET_BASE64_ALPHABET[(currentValue >> 10) & 0x3f]);
+			result.append(FREENET_BASE64_ALPHABET[(currentValue >> 4) & 0x3f]);
+			result.append(FREENET_BASE64_ALPHABET[(currentValue << 2) & 0x3f]);
+			result.append("=");
+		}
+		return result.toString();
+	}
+
+	public byte[] decode(String data) {
+		ByteArrayOutputStream dataOutput = new ByteArrayOutputStream(data.length() * 3 / 4);
+		try {
+			int currentValue = 0;
+			int index = 0;
+			for (char c : data.toCharArray()) {
+				if (c == '=') {
+					break;
+				}
+				currentValue = (currentValue << 6) | REVERSE_FREENET_BASE64_ALPHABET[c];
+				if (index % 4 == 3) {
+					dataOutput.write((currentValue >> 16) & 0xff);
+					dataOutput.write((currentValue >> 8) & 0xff);
+					dataOutput.write(currentValue & 0xff);
+				}
+				index++;
+			}
+			if (index % 4 == 2) {
+				dataOutput.write((currentValue >> 4) & 0xff);
+			} else if (index % 4 == 3) {
+				dataOutput.write((currentValue >> 10) & 0xff);
+				dataOutput.write((currentValue >> 2) & 0xff);
+			}
+			return dataOutput.toByteArray();
+		} finally {
+			try {
+				dataOutput.close();
+			} catch (IOException e) {
+				throw new RuntimeException(e);
+			}
+		}
+	}
+
+}