[freenet-cvs] r11195 - trunk/freenet/src/freenet/clients/http/filter

[toad at freenetproject.org]

Author: toad
Date: 2006-12-02 16:48:30 +0000 (Sat, 02 Dec 2006)
New Revision: 11195

Added:
   trunk/freenet/src/freenet/clients/http/filter/GIFFilter.java
Modified:
   trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
Log:
Basic GIF filter too. (Again, this only checks the header).

Modified: trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java	2006-12-02 16:42:54 UTC (rev 11194)
+++ trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java	2006-12-02 16:48:30 UTC (rev 11195)
@@ -39,7 +39,7 @@
 		
 		// GIF - probably safe - FIXME check this out, write filters 
 		register(new MIMEType("image/gif", "gif", new String[0], new String[0], 
-				true, false, null, null, false, false, false, false, false, false,
+				true, false, new GIFFilter(), null, false, false, false, false, false, false,
 				"GIF image - probably not dangerous",
 				"GIF image - probably not dangerous but you should wipe any comments",
 				false, null, null));

Added: trunk/freenet/src/freenet/clients/http/filter/GIFFilter.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/GIFFilter.java	2006-12-02 16:42:54 UTC (rev 11194)
+++ trunk/freenet/src/freenet/clients/http/filter/GIFFilter.java	2006-12-02 16:48:30 UTC (rev 11195)
@@ -0,0 +1,75 @@
+/* This code is part of Freenet. It is distributed under the GNU General
+ * Public License, version 2 (or at your option any later version). See
+ * http://www.gnu.org/ for further details of the GPL. */
+package freenet.clients.http.filter;
+
+import java.io.BufferedInputStream;
+import java.io.DataInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Arrays;
+import java.util.HashMap;
+
+import freenet.support.HTMLNode;
+import freenet.support.io.Bucket;
+import freenet.support.io.BucketFactory;
+
+/**
+ * Content filter for PNG's.
+ * This one just verifies that a PNG is valid, and throws if it isn't.
+ */
+public class GIFFilter implements ContentDataFilter {
+
+	static final String ERROR_MESSAGE = 
+		"The file you tried to fetch is not a GIF. It does not include a valid GIF header. "+
+		"It might be some other file format, and your browser may do something horrible with it, "+
+		"therefore we have blocked it.";
+	
+	static final int HEADER_SIZE = 6;
+	static final byte[] gif87aHeader =
+		{ (byte)'G', (byte)'I', (byte)'F', (byte)'8', (byte)'7', (byte)'a' };
+	static final byte[] gif89aHeader =
+		{ (byte)'G', (byte)'I', (byte)'F', (byte)'8', (byte)'9', (byte)'a' };
+		
+	
+	public Bucket readFilter(Bucket data, BucketFactory bf, String charset,
+			HashMap otherParams, FilterCallback cb) throws DataFilterException,
+			IOException {
+		if(data.size() < 6) {
+			throwHeaderError("Too short", "The file is too short to be a GIF.");
+		}
+		InputStream is = data.getInputStream();
+		BufferedInputStream bis = new BufferedInputStream(is);
+		DataInputStream dis = new DataInputStream(bis);
+		try {
+			// Check the header
+			byte[] headerCheck = new byte[HEADER_SIZE];
+			dis.read(headerCheck);
+			if((!Arrays.equals(headerCheck, gif87aHeader)) && (!Arrays.equals(headerCheck, gif89aHeader))) {
+				throwHeaderError("Invalid header", "The file does not contain a valid GIF header.");
+			}
+		} finally {
+			dis.close();
+		}
+		return data;
+	}
+
+	private void throwHeaderError(String shortReason, String reason) throws DataFilterException {
+		// Throw an exception
+		String message = ERROR_MESSAGE;
+		if(reason != null) message += ' ' + reason;
+		String msg = "Not a GIF";
+		if(shortReason != null)
+			msg += " - " + shortReason;
+		throw new DataFilterException(shortReason, shortReason,
+				"<p>"+message+"</p>", new HTMLNode("p").addChild("#", message));
+	}
+
+	public Bucket writeFilter(Bucket data, BucketFactory bf, String charset,
+			HashMap otherParams, FilterCallback cb) throws DataFilterException,
+			IOException {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+}