We rewrite static header table handling in nghttp2_hd.c. We expand
nghttp2_token to include all static header table entries, and fully
use them in header compression and decompression. The lookup function
is now located in nghttp2_hd.c. We add new nghttp2_hd_inflate_hd2()
function to export token value for header name, then we pass it to
nghttp2_http_on_header function, so that we don't have to look up
token there. We carefully set enum value of token to static table
index, so looking up static table is now O(1), assuming we have token.
nghttp2 library now use Literal Header Field never Indexed for
"authorization" header field and small "cookie" header field,
regardless of nghttp2_nv.flags.
nghttp2_mem structure is introduced to hold custom memory allocator
functions and user supplied pointer. nghttp2_mem object can be passed
to nghttp2_session_client_new3(), nghttp2_session_server_new3(),
nghttp2_hd_deflate_new2() and nghttp2_hd_inflate_new2() to replace
standard malloc(), free(), calloc() and realloc(). nghttp2_mem
structure has user supplied pointer mem_user_data which can be used as
per session/object memory pool.
This commits changes the upper bound of one header field size (the sum
of the length of name and value) to 64KiB by default. We may add an
option to change this upper bound in the future.
Previously in inflater we reserve new ringbuffer when table size is
changed. This may be potentially a problem if new table size is very
large number. When inflater is not used directly by application, this
is not a problem because application can choose the buffer size. On
the other hand, if application uses inflater directly and it does not
have control of new buffer size (e.g., protocol dissector), then we
just fail to allocate large buffer in
nghttp2_hd_inflate_change_table_size() without actually use such huge
buffer. This change defers the actual allocation of buffer when it is
actually needed so that we will fail when it is absolutely needed.
Previously we use 2 separate buffer for each name and value. The
problem is we would waste buffer space for name because it is usually
small. Also tuning buffer size for each buffer separately is not
elegant and current HTTP server practice is that one buffer for 1
name/value pair. This commit unifies 2 buffers into 1.
It is generally useful to know what is the cause of the error. Since
we expose HPACK API, it is friendly to tell application the
insufficient buffer size is a culprit.
Tatsuhiro Tsujikawa
Alexis La Goutte