Add support for the x-webkit-deflate-frame extension

Created by: oleavr

This is limited to inflate-only for now — so the server may send compressed data, but the client will (for now) always send uncompressed data to the server.

AndroidAsync/src/com/koushikdutta/async/http/HybiParser.java

@@ -40,16 +40,20 @@ import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 import java.util.Arrays;
 import java.util.List;
+import java.util.zip.DataFormatException;
+import java.util.zip.Inflater;
 
 abstract class HybiParser {
     private static final String TAG = "HybiParser";
 
     private boolean mMasking = true;
+    private boolean mDeflate = false;
 
     private int     mStage;
 
     private boolean mFinal;
     private boolean mMasked;
+    private boolean mDeflated;
     private int     mOpcode;
     private int     mLengthSize;
     private int     mLength;
@@ -61,6 +65,8 @@ abstract class HybiParser {
     private boolean mClosed = false;
 
     private ByteArrayOutputStream mBuffer = new ByteArrayOutputStream();
+    private Inflater mInflater = new Inflater(true);
+    private byte[] mInflateBuffer = new byte[4096];
 
     private static final int BYTE   = 255;
     private static final int FIN    = 128;
@@ -106,11 +112,33 @@ abstract class HybiParser {
         }
         return payload;
     }
-    
+
+    private byte[] inflate(byte[] payload) throws DataFormatException {
+        ByteArrayOutputStream inflated = new ByteArrayOutputStream();
+
+        mInflater.setInput(payload);
+        while (!mInflater.needsInput()) {
+            int chunkSize = mInflater.inflate(mInflateBuffer);
+            inflated.write(mInflateBuffer, 0, chunkSize);
+        }
+
+        mInflater.setInput(new byte[] { 0, 0, -1, -1 });
+        while (!mInflater.needsInput()) {
+            int chunkSize = mInflater.inflate(mInflateBuffer);
+            inflated.write(mInflateBuffer, 0, chunkSize);
+        }
+
+        return inflated.toByteArray();
+    }
+
     public void setMasking(boolean masking) {
         mMasking = masking;
     }
-    
+
+    public void setDeflate(boolean deflate) {
+        mDeflate = deflate;
+    }
+
     DataCallback mStage0 = new DataCallback() {
         @Override
         public void onDataAvailable(DataEmitter emitter, ByteBufferList bb) {
@@ -208,12 +236,13 @@ abstract class HybiParser {
         boolean rsv2 = (data & RSV2) == RSV2;
         boolean rsv3 = (data & RSV3) == RSV3;
 
-        if (rsv1 || rsv2 || rsv3) {
+        if ((!mDeflate && rsv1) || rsv2 || rsv3) {
             throw new ProtocolError("RSV not zero");
         }
 
         mFinal   = (data & FIN) == FIN;
         mOpcode  = (data & OPCODE);
+        mDeflated = rsv1;
         mMask    = new byte[0];
         mPayload = new byte[0];
 
@@ -324,6 +353,13 @@ abstract class HybiParser {
 
     private void emitFrame() throws IOException {
         byte[] payload = mask(mPayload, mMask, 0);
+        if (mDeflated) {
+            try {
+                payload = inflate(payload);
+            } catch (DataFormatException e) {
+                throw new IOException("Invalid deflated data");
+            }
+        }
         int opcode = mOpcode;
 
         if (opcode == OP_CONTINUATION) {

AndroidAsync/src/com/koushikdutta/async/http/WebSocketImpl.java

@@ -71,7 +71,7 @@ public class WebSocketImpl implements WebSocket {
             pending = null;
     }
 
-    private void setupParser(boolean masking) {
+    private void setupParser(boolean masking, boolean deflate) {
         mParser = new HybiParser(mSocket) {
             @Override
             protected void report(Exception ex) {
@@ -100,6 +100,7 @@ public class WebSocketImpl implements WebSocket {
             }
         };
         mParser.setMasking(masking);
+        mParser.setDeflate(deflate);
         if (mSocket.isPaused())
             mSocket.resume();
     }
@@ -126,7 +127,7 @@ public class WebSocketImpl implements WebSocket {
 //            response.getHeaders().getHeaders().set("Access-Control-Allow-Origin", "http://" + origin);
         response.writeHead();
         
-        setupParser(false);
+        setupParser(false, false);
     }
     
     public static void addWebSocketUpgradeHeaders(AsyncHttpRequest req, String protocol) {
@@ -134,6 +135,7 @@ public class WebSocketImpl implements WebSocket {
         final String key = Base64.encodeToString(toByteArray(UUID.randomUUID()),Base64.NO_WRAP);
         headers.set("Sec-WebSocket-Version", "13");
         headers.set("Sec-WebSocket-Key", key);
+        headers.set("Sec-WebSocket-Extensions", "x-webkit-deflate-frame");
         headers.set("Connection", "Upgrade");
         headers.set("Upgrade", "websocket");
         if (protocol != null)
@@ -166,9 +168,17 @@ public class WebSocketImpl implements WebSocket {
         String expected = SHA1(concat).trim();
         if (!sha1.equalsIgnoreCase(expected))
             return null;
+        String extensions = requestHeaders.get("Sec-WebSocket-Extensions");
+        boolean deflate = false;
+        if (extensions != null) {
+            if (extensions.equals("x-webkit-deflate-frame"))
+                deflate = true;
+            else
+                return null;
+        }
 
         WebSocketImpl ret = new WebSocketImpl(response.detachSocket());
-        ret.setupParser(true);
+        ret.setupParser(true, deflate);
         return ret;
     }