HTTP/2 C library and tools

Nghttp2 v0.6.3

We happily announce yet another release of nghttp2 v0.6.3. It still implements h2-14 and HPACK-09.

This release addresses portability/compatibility issues reported by package maintainer and users. One of the problem was caused by use of std::future. Some platform lacks std::future, which causes compile error on application under src directoy. In this release, we check that whether std::future is available or not and if not, define NOTHREADS and exclude multi threading code entirely from applications.

Surprisingly, nghttp2 did not check first SETTINGS (a part of conneciton preface) strictly. From this release, nghttp2 library code checks whether SETTINGS is received as a first frame and if other frame type is received, treats it as PROTOCOL_ERROR.

The library code itself was optimized a bit more and improved its efficiency.