From 94ab0dc4425b05e8691c0954f70c1859d0b7294c Mon Sep 17 00:00:00 2001
From: Moses Nakamura <nnythm@gmail.com>
Date: Mon, 18 Dec 2017 20:41:09 -0500
Subject: [PATCH] codec-http2: Better keep track of nameLength in
 HpackDecoder.decode

Motivation:

http/2 counts header sizes somewhat inconsistently.  Sometimes, headers
which are substantively less than the header list size will be measured
as longer than the header list size.

Modifications:

Keep better track of the nameLength of a given name, so that we don't
accidentally end up reusing a nameLength.

Result:

More consistent measurement of header list size.

Fixes #7511.
---
 .../handler/codec/http2/HpackDecoder.java     |  3 +++
 .../handler/codec/http2/HpackDecoderTest.java | 22 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/codec-http2/src/main/java/io/netty/handler/codec/http2/HpackDecoder.java b/codec-http2/src/main/java/io/netty/handler/codec/http2/HpackDecoder.java
index ce81f7c498..07b1e30b53 100644
--- a/codec-http2/src/main/java/io/netty/handler/codec/http2/HpackDecoder.java
+++ b/codec-http2/src/main/java/io/netty/handler/codec/http2/HpackDecoder.java
@@ -162,6 +162,7 @@ final class HpackDecoder {
                             default:
                                 // Index was stored as the prefix
                                 name = readName(index);
+                                nameLength = name.length();
                                 state = READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX;
                         }
                     } else if ((b & 0x20) == 0x20) {
@@ -187,6 +188,7 @@ final class HpackDecoder {
                             default:
                             // Index was stored as the prefix
                             name = readName(index);
+                            nameLength = name.length();
                             state = READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX;
                         }
                     }
@@ -205,6 +207,7 @@ final class HpackDecoder {
                 case READ_INDEXED_HEADER_NAME:
                     // Header Name matches an entry in the Header Table
                     name = readName(decodeULE128(in, index));
+                    nameLength = name.length();
                     state = READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX;
                     break;
 
diff --git a/codec-http2/src/test/java/io/netty/handler/codec/http2/HpackDecoderTest.java b/codec-http2/src/test/java/io/netty/handler/codec/http2/HpackDecoderTest.java
index 8dd885400c..04552b9263 100644
--- a/codec-http2/src/test/java/io/netty/handler/codec/http2/HpackDecoderTest.java
+++ b/codec-http2/src/test/java/io/netty/handler/codec/http2/HpackDecoderTest.java
@@ -455,4 +455,26 @@ public class HpackDecoderTest {
             in.release();
         }
     }
+
+    @Test
+    public void testDecodeCountsNamesOnlyOnce() throws Http2Exception {
+        ByteBuf in = Unpooled.buffer(200);
+        try {
+            hpackDecoder.setMaxHeaderListSize(3500, 4000);
+            HpackEncoder hpackEncoder = new HpackEncoder(true);
+
+            // encode headers that are slightly larger than maxHeaderListSize
+            // but smaller than maxHeaderListSizeGoAway
+            Http2Headers toEncode = new DefaultHttp2Headers();
+            toEncode.add(String.format("%03000d", 0).replace('0', 'f'), "value");
+            toEncode.add("accept", "value");
+            hpackEncoder.encodeHeaders(1, in, toEncode, NEVER_SENSITIVE);
+
+            Http2Headers decoded = new DefaultHttp2Headers();
+            hpackDecoder.decode(1, in, decoded);
+            assertEquals(2, decoded.size());
+        } finally {
+            in.release();
+        }
+    }
 }