[freenet-cvs] r17726 - trunk/freenet/src/freenet/clients/http/filter

[nextg...@freenetproject.org]

Author: nextgens
Date: 2008-02-08 23:41:38 +0000 (Fri, 08 Feb 2008)
New Revision: 17726

Modified:
   trunk/freenet/src/freenet/clients/http/filter/PNGFilter.java
Log:
PNGFilter: Add more tests on chunktype/order

Modified: trunk/freenet/src/freenet/clients/http/filter/PNGFilter.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/PNGFilter.java        
2008-02-08 23:05:53 UTC (rev 17725)
+++ trunk/freenet/src/freenet/clients/http/filter/PNGFilter.java        
2008-02-08 23:41:38 UTC (rev 17726)
@@ -12,7 +12,6 @@

 import freenet.l10n.L10n;
 import freenet.support.CRC;
-import freenet.support.Fields;
 import freenet.support.HTMLNode;
 import freenet.support.HexUtil;
 import freenet.support.Logger;
@@ -43,7 +42,7 @@

        private final boolean deleteText;
        private final boolean deleteTimestamp;
-       private final boolean checkCRCs; // need a fair amount of memory
+       private final boolean checkCRCs;
        static final byte[] pngHeader =
                {(byte) 137, (byte) 80, (byte) 78, (byte) 71, (byte) 13, (byte) 
10, (byte) 26, (byte) 10};

@@ -107,11 +106,14 @@
                        }

                        // Check the chunks :
-                       // We should have an IHDR chunk at the beginning and a 
IEND at the end
+                       // @see 
http://www.libpng.org/pub/png/spec/1.2/PNG-Chunks.html#C.Summary-of-standard-chunks
                        boolean finished = false;
                        boolean hasSeenIHDR = false;
                        boolean hasSeenIEND = false;
-
+                       boolean hasSeenPLTE = false;
+                       boolean hasSeenIDAT = false;
+                       String lastChunkType = "";
+                       
                        while(!finished) {
                                boolean skip = false;
                                if(baos != null)
@@ -194,6 +196,18 @@
                                                throw new IOException("Two IEND 
chunks detected!!");
                                        hasSeenIEND = true;
                                }
+                               
+                               if(!skip && 
"PLTE".equalsIgnoreCase(chunkTypeString)) {
+                                       if(hasSeenIDAT)
+                                               throw new IOException("PLTE 
must be before IDAT");
+                                       hasSeenPLTE = true;
+                               }
+                               
+                               if(!skip && 
"IDAT".equalsIgnoreCase(chunkTypeString)) {
+                                       if(hasSeenIDAT && 
!"IDAT".equalsIgnoreCase(lastChunkType))
+                                               throw new IOException("Multiple 
IDAT chunks must be consecutive!");
+                                       hasSeenIDAT = true;
+                               }

                                if(dis.available() < 1) {
                                        if(!(hasSeenIEND && hasSeenIHDR))
@@ -213,6 +227,7 @@
                                                Logger.minor(this, "Writing " + 
chunkTypeString + " (" + baos.size() + ") to the output bucket");
                                        baos.writeTo(output);
                                }
+                               lastChunkType = chunkTypeString;
                        }

                        dis.close();