Author: toad
Date: 2006-03-17 20:35:08 +0000 (Fri, 17 Mar 2006)
New Revision: 8268
Added:
trunk/freenet/src/freenet/clients/http/filter/
trunk/freenet/src/freenet/clients/http/filter/CharsetExtractor.java
trunk/freenet/src/freenet/clients/http/filter/ContentDataFilter.java
trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
trunk/freenet/src/freenet/clients/http/filter/FilterCallback.java
trunk/freenet/src/freenet/clients/http/filter/MIMEType.java
Log:
Beginnings of content anonymity filter.
Added: trunk/freenet/src/freenet/clients/http/filter/CharsetExtractor.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/CharsetExtractor.java
2006-03-17 20:14:47 UTC (rev 8267)
+++ trunk/freenet/src/freenet/clients/http/filter/CharsetExtractor.java
2006-03-17 20:35:08 UTC (rev 8268)
@@ -0,0 +1,13 @@
+package freenet.clients.http.filter;
+
+import freenet.support.Bucket;
+
+/**
+ * For a specific text/-based MIME type, extracts the charset if
+ * possible.
+ */
+public interface CharsetExtractor {
+
+ String getCharset(Bucket data);
+
+}
Added: trunk/freenet/src/freenet/clients/http/filter/ContentDataFilter.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/ContentDataFilter.java
2006-03-17 20:14:47 UTC (rev 8267)
+++ trunk/freenet/src/freenet/clients/http/filter/ContentDataFilter.java
2006-03-17 20:35:08 UTC (rev 8268)
@@ -0,0 +1,12 @@
+package freenet.clients.http.filter;
+
+import freenet.support.Bucket;
+
+/**
+ * Data filter for a specific MIME type.
+ */
+public interface ContentDataFilter {
+
+ public Bucket filter(Bucket data, String charset, FilterCallback cb);
+
+}
Added: trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
2006-03-17 20:14:47 UTC (rev 8267)
+++ trunk/freenet/src/freenet/clients/http/filter/ContentFilter.java
2006-03-17 20:35:08 UTC (rev 8268)
@@ -0,0 +1,89 @@
+package freenet.clients.http.filter;
+
+import java.util.Hashtable;
+
+/**
+ * Freenet content filter. This doesn't actually do any filtering,
+ * it organizes everything and maintains the database.
+ */
+public class ContentFilter {
+
+ static final Hashtable mimeTypesByName = new Hashtable();
+
+ static {
+ init();
+ }
+
+ public static void init() {
+ // Register known MIME types
+
+ // Plain text
+ register(new MIMEType("text/plain", "txt", new String[0], new
String[] { "text", "pot" },
+ true, true, null, null, false, false, false,
false, false, false,
+ "Plain text - not dangerous unless your browser
is stupid (e.g. Internet Explorer)",
+ "Plain text - not dangerous unless you include
compromizing information",
+ true, "iso-8859-1", null));
+
+ // 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,
+ "GIF image - probably not dangerous",
+ "GIF image - probably not dangerous but you
should wipe any comments",
+ false, null, null));
+
+ // JPEG - probably safe - FIXME check this out, write filters
+ register(new MIMEType("image/jpeg", "jpeg", new String[0], new
String[] { "jpg" },
+ true, true, null, null, false, false, false,
false, false, false,
+ "JPEG image - probably not dangerous",
+ "JPEG image - probably not dangerous", false,
null, null));
+
+ // 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,
+ "PNG image - probably not dangerous",
+ "PNG image - probably not dangerous but you
should wipe any comments or text blocks",
+ false, null, null));
+
+ // PDF - very dangerous - FIXME ideally we would have a filter,
this is such a common format...
+ register(new MIMEType("application/pdf", "pdf", new String[] {
"application/x-pdf" }, new String[0],
+ false, false, null, null, true, true, true,
true, true, true,
+ "Adobe(R) PDF document - VERY DANGEROUS!",
+ "Adobe(R) PDF document - VERY DANGEROUS!",
+ false, null, null));
+
+ // HTML - dangerous if not filtered
+ register(new MIMEType("text/html", "html", new String[] {
"text/xhtml", "text/xml+xhtml" }, new String[] { "htm" },
+ false, false /* maybe? */, new
HTMLReadFilter(), new HTMLWriteFilter(),
+ true, true, true, true, true, true, false,
+ "HTML - not dangerous if filtered",
+ "HTML - may contain dangerous metadata etc;
suggest you check it by hand",
+ true, "iso-8859-1", new
HTMLCharsetExtractor()));
+
+ // CSS - danagerous if not filtered, not sure about the filter
+ register(new MIMEType("text/css", "css", new String[0], new
String[0],
+ false, false /* unknown */, new
CSSReadFilter(), null,
+ true, true, true, true, true, false,
+ "CSS (cascading style sheet, usually used with
HTML) - probably not dangerous if filtered, but the filter is not a whitelist
filter so take care",
+ "CSS (cascading style sheet, usually used with
HTML) - this can probably contain metadata, check it by hand",
+ true, "iso-8859-1", new CSSCharsetExtractor()));
+
+ }
+
+ public static void register(MIMEType mimeType) {
+ synchronized(mimeTypesByName) {
+ mimeTypesByName.put(mimeType.primaryMimeType, mimeType);
+ String[] alt = mimeType.alternateMimeTypes;
+ if(alt != null && alt.length > 0) {
+ for(int i=0;i<alt.length;i++)
+ mimeTypesByName.put(alt[i], mimeType);
+ }
+ }
+ }
+
+ public static MIMEType getMIMEType(String mimeType) {
+ return (MIMEType) mimeTypesByName.get(mimeType);
+ }
+
+ public static
+
+}
Added: trunk/freenet/src/freenet/clients/http/filter/FilterCallback.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/FilterCallback.java
2006-03-17 20:14:47 UTC (rev 8267)
+++ trunk/freenet/src/freenet/clients/http/filter/FilterCallback.java
2006-03-17 20:35:08 UTC (rev 8268)
@@ -0,0 +1,26 @@
+package freenet.clients.http.filter;
+
+import freenet.keys.FreenetURI;
+
+/**
+ * Callback to be provided to a content filter.
+ */
+public interface FilterCallback {
+
+ /**
+ * Process a URI.
+ * If it cannot be turned into something sufficiently safe, then return
null.
+ */
+ public FreenetURI processURI(FreenetURI uri);
+
+ /**
+ * Should we allow GET forms?
+ */
+ public boolean allowGetForms();
+
+ /**
+ * Should we allow POST forms?
+ */
+ public boolean allowPostForms();
+
+}
Added: trunk/freenet/src/freenet/clients/http/filter/MIMEType.java
===================================================================
--- trunk/freenet/src/freenet/clients/http/filter/MIMEType.java 2006-03-17
20:14:47 UTC (rev 8267)
+++ trunk/freenet/src/freenet/clients/http/filter/MIMEType.java 2006-03-17
20:35:08 UTC (rev 8268)
@@ -0,0 +1,79 @@
+package freenet.clients.http.filter;
+
+/**
+ * A MIME type, for purposes of the filter.
+ */
+public class MIMEType {
+
+ final String primaryMimeType;
+ final String[] alternateMimeTypes;
+
+ final String primaryExtension;
+ final String[] alternateExtensions;
+
+ /** Is the data safe to read as-is? This is true for text/plain. */
+ final boolean safeToRead;
+
+ /** Is the data safe to write as-is? */
+ final boolean safeToWrite;
+
+ /** Content filter to make data safe to read */
+ final ContentDataFilter readFilter;
+
+ /** Content filter to make data safe to write */
+ final ContentDataFilter writeFilter;
+
+ // Detail. Not necessarily an exhaustive list.
+
+ final boolean dangerousLinks;
+
+ final boolean dangerousInlines;
+
+ final boolean dangerousScripting;
+
+ final boolean dangerousReadMetadata;
+
+ final boolean dangerousWriteMetadata;
+
+ final boolean dangerousToWriteEvenWithFilter;
+
+ // These are in addition to the above
+
+ final String readDescription;
+
+ final String writeDescription;
+
+ final boolean takesACharset;
+
+ final String defaultCharset;
+
+ final CharsetExtractor charsetExtractor;
+
+ MIMEType(String type, String ext, String[] extraTypes, String[]
extraExts,
+ boolean safeToRead, boolean safeToWrite,
ContentDataFilter readFilter,
+ ContentDataFilter writeFilter, boolean dangerousLinks,
boolean dangerousInlines,
+ boolean dangerousScripting, boolean
dangerousReadMetadata,
+ boolean dangerousWriteMetadata, boolean
dangerousToWriteEvenWithFilter,
+ String readDescription, String writeDescription,
boolean takesACharset,
+ String defaultCharset, CharsetExtractor
charsetExtractor) {
+ this.primaryMimeType = type;
+ this.primaryExtension = ext;
+ this.alternateMimeTypes = extraTypes;
+ this.alternateExtensions = extraExts;
+ this.safeToRead = safeToRead;
+ this.safeToWrite = safeToWrite;
+ this.readFilter = readFilter;
+ this.writeFilter = writeFilter;
+ this.dangerousLinks = dangerousLinks;
+ this.dangerousInlines = dangerousInlines;
+ this.dangerousScripting = dangerousScripting;
+ this.dangerousReadMetadata = dangerousReadMetadata;
+ this.dangerousWriteMetadata = dangerousWriteMetadata;
+ this.dangerousToWriteEvenWithFilter =
dangerousToWriteEvenWithFilter;
+ this.readDescription = readDescription;
+ this.writeDescription = writeDescription;
+ this.takesACharset = takesACharset;
+ this.defaultCharset = defaultCharset;
+ this.charsetExtractor = charsetExtractor;
+ }
+}
