Similarity between nghttp2's nghttp2_hd_huffman.c and libhpack's huffman.c

[tatsuhiro-t]

I found that nghttp2's nghttp2_hd_huffman.c and libhpack's huffman.c are quite similar. Actually, except for memory management and cosmetic code style (variable name), they are almost identical. The data structure in libhpack's huffman.h is quite similar to nghttp2's nghttp2_hd_huffman.h too.

• https://github.com/tatsuhiro-t/nghttp2/blob/master/lib/nghttp2_hd_huffman.c
• https://github.com/alobbs/libhpack/blob/master/libhpack/huffman.c

I rewrote huffman decoding algorithm in Jan 24, 2014 into the current form. Similar changes were committed in libhpack in Feb 22, 2014. Even before that, they look very similar.

• https://github.com/tatsuhiro-t/nghttp2/blob/9eb031ce837883233a30b19317f32acb920be62b/lib/nghttp2_hd_huffman.c
• https://github.com/alobbs/libhpack/blob/6ff4f73d63a95220fb512200e8d0bcf7390ce96b/libhpack/huffman.c

I saw several HPACK huffman implementations, but I've never met this degree of similarity.

If libhpack's huffman.c is a copy of nghttp2's nghttp2_hd_huffman.c without substantial changes, then MIT license requires that our copyright notice must be appeared in libhpack source code:

/*
 * nghttp2 - HTTP/2 C Library
 *
 * Copyright (c) 2013 Tatsuhiro Tsujikawa
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

I'd like to hear your thoughts.
Apologies in advance if this is a false claim.