Motivation:
When a sender sends too large of headers it should not unnecessarily
kill the connection, as killing the connection is a heavy-handed
solution while SETTINGS_MAX_HEADER_LIST_SIZE is advisory and may be
ignored.
The maxHeaderListSizeGoAway limit in HpackDecoder is unnecessary because
any headers causing the list to exceeding the max size can simply be
thrown away. In addition, DefaultHttp2FrameReader.HeadersBlockBuilder
limits the entire block to maxHeaderListSizeGoAway. Thus individual
literals are limited to maxHeaderListSizeGoAway.
(Technically, literals are limited to 1.6x maxHeaderListSizeGoAway,
since the canonical Huffman code has a maximum compression ratio of
.625. However, the "unnecessary" limit in HpackDecoder was also being
applied to compressed sizes.)
Modifications:
Remove maxHeaderListSizeGoAway checking in HpackDecoder and instead
eagerly throw away any headers causing the list to exceed
maxHeaderListSize.
Result:
Fewer large header cases will trigger connection-killing.
DefaultHttp2FrameReader.HeadersBlockBuilder will still kill the
connection when maxHeaderListSizeGoAway is exceeded, however.
Fixes#7887
Motivation:
When connecting to an HTTP/2 server that did not set any value for the
SETTINGS_MAX_HEADER_LIST_SIZE in the settings frame, the netty client was
imposing an arbitrary maximum header list size of 8kB. There should be no need
for the client to enforce such a limit if the server has not specified any
limit. This caused an issue for a grpc-java client that needed to send a large
header to a server via an Envoy proxy server. The error condition is
demonstrated here: https://github.com/JLofgren/demo-grpc-java-bug-4284
Fixes grpc-java issue #4284 - https://github.com/grpc/grpc-java/issues/4284
and netty issue #7825 - https://github.com/netty/netty/issues/7825
Modifications:
In HpackEncoder use MAX_HEADER_LIST_SIZE as default maxHeader list size.
Result:
HpackEncoder will only enforce a max header list size if the server has
specified a limit in its settings frame.
Motivation:
According to the spec:
All pseudo-header fields MUST appear in the header block before regular
header fields. Any request or response that contains a pseudo-header
field that appears in a header block after
a regular header field MUST be treated as malformed (Section 8.1.2.6).
Pseudo-header fields are only valid in the context in which they are defined.
Pseudo-header fields defined for requests MUST NOT appear in responses;
pseudo-header fields defined for responses MUST NOT appear in requests.
Pseudo-header fields MUST NOT appear in trailers.
Endpoints MUST treat a request or response that contains undefined or
invalid pseudo-header fields as malformed (Section 8.1.2.6).
Clients MUST NOT accept a malformed response. Note that these requirements
are intended to protect against several types of common attacks against HTTP;
they are deliberately strict because being permissive can expose
implementations to these vulnerabilities.
Modifications:
- Introduce validation in HPackDecoder
Result:
- Requests with unknown pseudo-field headers are rejected
- Requests with containing response specific pseudo-headers are rejected
- Requests where pseudo-header appear after regular header are rejected
- h2spec 8.1.2.1 pass
Motivation:
The internal.hpack classes are no longer exposed in our public APIs and can be made package private in the http2 package.
Modifications:
- Make the hpack classes package private in the http2 package
Result:
Less APIs exposed as public.
