From 38f6455c83dd68c80b2f667388d45cf6a28688ee Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Wed, 4 Dec 2024 14:17:02 -0800
Subject: Better websocket reader

fix bug double-render
---
 .../com/seaofnodes/simple/SimpleWebSocket.java     | 36 +++++++++++++++++++---
 1 file changed, 32 insertions(+), 4 deletions(-)

(limited to 'chapter18/src/main/java/com')

diff --git a/chapter18/src/main/java/com/seaofnodes/simple/SimpleWebSocket.java b/chapter18/src/main/java/com/seaofnodes/simple/SimpleWebSocket.java
index f9a85d19..1ce766ff 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/SimpleWebSocket.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/SimpleWebSocket.java
@@ -55,15 +55,35 @@ class SimpleWebSocket extends ServerSocket {
     int _x, _len;
     private int rawget() { assert _x<_len; return _ins[_x++]&0xFF; }
 
+    // TODO: Flip to Direct Byte Buffer, this is just a poor-mans version
+    private void flipRead() throws IOException {
+        // Move _x to _len to offset 0
+        System.arraycopy(_ins,_x,_ins,0,(_len-_x));
+        _len = _len-_x;
+        _x=0;
+        // Read more
+        int len = _in.read(_ins,_len,_ins.length-_len);
+        if( len == -1 )
+            throw Utils.TODO(); // EOF
+        _len += len;
+    }
+    // Block until you read at least len
+    private void atLeast(int len) throws IOException {
+        if( _x+len <= _len ) return;
+        flipRead();
+    }
+
+
     // Classic read from browser client.  Encoded, so decoded here
     public String get() throws IOException {
-        _len = _in.read(_ins);  _x=0;
+        atLeast(1);             // Need 1 byte for opcode
         int op = rawget();
-        if( (op&0x80)!=0x80 ) // FIN bit not set?
-            throw Utils.TODO("Multi-part from client: "+op); // Multipart message
-        op &= 0x7F;         // Strip FIN bit
+        if( (op&0x80)!=0x80 )   // FIN bit not set?
+            throw Utils.TODO( "Multi-part from client: " + op ); // Multipart message
+        op &= 0x7F;             // Strip FIN bit
         switch( op&15) {
         case 1: {
+            atLeast(5);         // Min message length
             // Message length
             int len = rawget()-128;
             if( len > 125 ) {
@@ -71,11 +91,13 @@ class SimpleWebSocket extends ServerSocket {
                     throw Utils.TODO(); // Multi-byte length
                 len = (rawget()<<8) | rawget();
             }
+            atLeast(len+4);     // Rest of message
             // Encoding key
             _key[0] = (byte)rawget();
             _key[1] = (byte)rawget();
             _key[2] = (byte)rawget();
             _key[3] = (byte)rawget();
+
             // Decode bytes
             for( int i=0; i<len; i++ )
                 _str[i] = (byte)(rawget() ^ _key[i & 3]);
@@ -84,6 +106,12 @@ class SimpleWebSocket extends ServerSocket {
         }
             // Client closes
         case 8: return null;
+            // Ping
+        case 9:
+            // Send a PONG back.  TODO: echo PING data in the PONG
+            _out.write(0x8A); // FIN + PONG
+            _out.write(0x00); // LENGTH==0
+            return get();
             // Not (yet) implemented: continuation frames, ping/pong
         default:
             throw Utils.TODO("Unexpected op from client: "+op); // Multi-part message
-- 
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