Adds a ParseTrailers method to SpdyUtils, with some basic validation of the header keys provided.

net/quic/spdy_utils.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/spdy_utils.h"
 
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
@@ skipping 47 matching lines @@
       }
       if (new_value != *content_length) {
         return false;
       }
     }
   }
 
   return true;
 }
 
+// static
+bool SpdyUtils::ParseTrailers(const char* data,
+                              uint32 data_len,
+                              size_t* final_byte_offset,
+                              SpdyHeaderBlock* trailers) {
+  SpdyFramer framer(HTTP2);
+  if (!framer.ParseHeaderBlockInBuffer(data, data_len, trailers) ||
+      trailers->empty()) {
+    DVLOG(1) << "Request Trailers are invalid.";
+    return false;  // Trailers were invalid.
+  }
+
+  // Pull out the :final-offset pseudo header which indicates the number of
+  // response body bytes expected.
+  auto it = trailers->find(":final-offset");
+  if (it == trailers->end() ||
+      !base::StringToSizeT(it->second, final_byte_offset)) {
+    DVLOG(1) << ":final-offset not present";
+    return false;  // :final-offset key must be present.
+  }
+  // :final-offset header is no longer used.
+  trailers->erase(it->first);
+
+  // Trailers must not have empty keys, and must not contain pseudo headers.
+  for (const auto& trailer : *trailers) {
+    base::StringPiece key = trailer.first;
+    base::StringPiece value = trailer.second;
+    if (key.starts_with(":")) {
+      DVLOG(1) << "Trailers must not contain pseudo-header: '" << key << "','"
+               << value << "'.";
+      return false;
+    }
+
+    // TODO(rjshade): Check for other forbidden keys, following the HTTP/2 spec.
+  }
+
+  DVLOG(1) << "Successfully parsed Trailers.";
+  return true;
+}
+
 }  // namespace net