Author: toad
Date: 2006-12-02 00:56:37 +0000 (Sat, 02 Dec 2006)
New Revision: 11190
Added:
trunk/freenet/src/freenet/clients/http/filter/PNGFilter.java
Modified:
trunk/freenet/src/freenet/clients/http/filter/CSSReadFilter.java
trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
Log:
Initial PNG filter. Currently it just checks for a signature.
However this is enough to stop at least one attack, provided that my patch to
firefox is (eventually) accepted.
Modified: trunk/freenet/src/freenet/clients/http/filter/CSSReadFilter.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/CSSReadFilter.java
2006-12-01 23:37:12 UTC (rev 11189)
+++ trunk/freenet/src/freenet/clients/http/filter/CSSReadFilter.java
2006-12-02 00:56:37 UTC (rev 11190)
@@ -52,7 +52,7 @@
explanation.addChild("#", " The page you are about to
display has an unknown character set. This means that we are not able to filter
the page, and it may compromize your anonymity.");
throw new DataFilterException("Warning: Unknown
character set ("+charset+ ')', "Warning: Unknown character set
("+HTMLEncoder.encode(charset)+ ')',
"<p><b>Unknown character set</b> The
page you are about to display has an unknown character set. "+
- "This means that we are not able to
filter the page, and it may compromize your anonymity.", explanation);
+ "This means that we are not able to
filter the page, and it may compromize your anonymity.</p>", explanation);
}
CSSParser parser = new CSSParser(r, w, false, cb);
parser.parse();
Modified: trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
2006-12-01 23:37:12 UTC (rev 11189)
+++ trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
2006-12-02 00:56:37 UTC (rev 11190)
@@ -52,7 +52,7 @@
// PNG - probably safe - FIXME check this out, write filters
register(new MIMEType("image/png", "png", new String[0], new
String[0],
- true, false, null, null, false, false, false,
false, true, false,
+ true, false, new PNGFilter(), null, false,
false, false, false, true, false,
"PNG image - probably not dangerous",
"PNG image - probably not dangerous but you
should wipe any comments or text blocks",
false, null, null));
Added: trunk/freenet/src/freenet/clients/http/filter/PNGFilter.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/PNGFilter.java
2006-12-01 23:37:12 UTC (rev 11189)
+++ trunk/freenet/src/freenet/clients/http/filter/PNGFilter.java
2006-12-02 00:56:37 UTC (rev 11190)
@@ -0,0 +1,53 @@
+/* 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 PNGFilter implements ContentDataFilter {
+
+ static final byte[] pngHeader =
+ { (byte)137, (byte)80, (byte)78, (byte)71, (byte)13, (byte)10,
(byte)26, (byte)10 };
+
+ public Bucket readFilter(Bucket data, BucketFactory bf, String charset,
+ HashMap otherParams, FilterCallback cb) throws
DataFilterException,
+ IOException {
+ InputStream is = data.getInputStream();
+ BufferedInputStream bis = new BufferedInputStream(is);
+ DataInputStream dis = new DataInputStream(bis);
+ // Check the header
+ byte[] headerCheck = new byte[pngHeader.length];
+ dis.read(headerCheck);
+ if(!Arrays.equals(headerCheck, pngHeader)) {
+ // Throw an exception
+ String message = "The file you tried to fetch is not a
PNG. It does not include a valid PNG header. "+
+ "It might be some other file format,
and your browser may do something horrible with it, "+
+ "therefore we have blocked it.";
+ throw new DataFilterException("Not a PNG - invalid
header", "Not a PNG - invalid header",
+ "<p>"+message+"</p>", new
HTMLNode("p").addChild("#", message));
+ }
+ return data;
+ }
+
+ public Bucket writeFilter(Bucket data, BucketFactory bf, String charset,
+ HashMap otherParams, FilterCallback cb) throws
DataFilterException,
+ IOException {
+ // TODO Auto-generated method stub
+ return null;
+ }
+
+}
