Deprecate HTTP/2 PAD_HIGH field and enforce max padding size to 256 octets.

net/spdy/spdy_protocol.h

Index: net/spdy/spdy_protocol.h
diff --git a/net/spdy/spdy_protocol.h b/net/spdy/spdy_protocol.h
index 1249bbe37b075cb3ffd6e9dde23ae50c08e3fa95..c80c0c06f29f9baac4d3c2a428e6d43e0d7ab397 100644
--- a/net/spdy/spdy_protocol.h
+++ b/net/spdy/spdy_protocol.h
@@ -55,6 +55,9 @@ const int32 kSpdySessionInitialWindowSize = 64 * 1024;  // 64 KBytes
 // Maximum window size for a Spdy stream or session.
 const int32 kSpdyMaximumWindowSize = 0x7FFFFFFF;  // Max signed 32bit int
 
+// Maximum padding size in octets for one DATA or HEADERS or PUSH_PROMISE frame.
+const int32 kPaddingSizePerFrame = 256;
+
 // SPDY 2 dictionary.
 // This is just a hacked dictionary to use for shrinking HTTP-like headers.
 const char kV2Dictionary[] =
@@ -294,8 +297,7 @@ enum SpdyDataFlags {
   DATA_FLAG_NONE = 0x00,
   DATA_FLAG_FIN = 0x01,
   DATA_FLAG_END_SEGMENT = 0x02,
-  DATA_FLAG_PAD_LOW = 0x08,
-  DATA_FLAG_PAD_HIGH = 0x10,
+  DATA_FLAG_PADDED = 0x08,
   DATA_FLAG_COMPRESSED = 0x20,
 };
 
@@ -314,13 +316,13 @@ enum SpdyPingFlags {
 enum SpdyHeadersFlags {
   HEADERS_FLAG_END_SEGMENT = 0x02,
   HEADERS_FLAG_END_HEADERS = 0x04,
-  HEADERS_FLAG_PAD_LOW = 0x08,
-  HEADERS_FLAG_PAD_HIGH = 0x10,
+  HEADERS_FLAG_PADDED = 0x08,
   HEADERS_FLAG_PRIORITY = 0x20,
 };
 
 enum SpdyPushPromiseFlags {
   PUSH_PROMISE_FLAG_END_PUSH_PROMISE = 0x04,
+  PUSH_PROMISE_FLAG_PADDED = 0x08,
 };
 
 // Flags on the SETTINGS control frame.
@@ -621,27 +623,16 @@ class NET_EXPORT_PRIVATE SpdyDataIR
 
   base::StringPiece data() const { return data_; }
 
-  bool pad_low() const { return pad_low_; }
-
-  bool pad_high() const { return pad_high_; }
+  bool padded() const { return padded_; }
 
   int padding_payload_len() const { return padding_payload_len_; }
 
   void set_padding_len(int padding_len) {
-    // The padding_len should be in (0, 65535 + 2].
-    // Note that SpdyFramer::GetDataFrameMaximumPayload() enforces the overall
-    // payload size later so we actually can't pad more than 16375 bytes.
     DCHECK_GT(padding_len, 0);
-    DCHECK_LT(padding_len, 65537);
-
-    if (padding_len <= 256) {
-      pad_low_ = true;
-      --padding_len;
-    } else {
-      pad_low_ = pad_high_ = true;
-      padding_len -= 2;
-    }
-    padding_payload_len_ = padding_len;
+    DCHECK_LE(padding_len, kPaddingSizePerFrame);
+    padded_ = true;
+    // The pad field takes one octet on the wire.
+    padding_payload_len_ = padding_len - 1;
   }
 
   // Deep-copy of data (keep private copy).
@@ -663,8 +654,7 @@ class NET_EXPORT_PRIVATE SpdyDataIR
   scoped_ptr<std::string> data_store_;
   base::StringPiece data_;
 
-  bool pad_low_;
-  bool pad_high_;
+  bool padded_;
   // padding_payload_len_ = desired padding length - len(padding length field).
   int padding_payload_len_;