aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/nghttp2/README.rst
blob: 19bbf2cfe08da509a67786dd91f95444c8d25463 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
nghttp2 - HTTP/2 C Library
==========================

This is an implementation of the Hypertext Transfer Protocol version 2
in C.

The framing layer of HTTP/2 is implemented as a reusable C library.
On top of that, we have implemented an HTTP/2 client, server and
proxy.  We have also developed load test and benchmarking tools for
HTTP/2.

An HPACK encoder and decoder are available as a public API.

Development Status
------------------

nghttp2 was originally developed based on `RFC 7540
<https://tools.ietf.org/html/rfc7540>`_ HTTP/2 and `RFC 7541
<https://tools.ietf.org/html/rfc7541>`_ HPACK - Header Compression for
HTTP/2.  Now we are updating our code to implement `RFC 9113
<https://datatracker.ietf.org/doc/html/rfc9113>`_.

The nghttp2 code base was forked from the spdylay
(https://github.com/tatsuhiro-t/spdylay) project.

Public Test Server
------------------

The following endpoints are available to try out our nghttp2
implementation.

* https://nghttp2.org/ (TLS + ALPN and HTTP/3)

  This endpoint supports ``h2``, ``h2-16``, ``h2-14``, and
  ``http/1.1`` via ALPN and requires TLSv1.2 for HTTP/2
  connection.

  It also supports HTTP/3.

* http://nghttp2.org/ (HTTP Upgrade and HTTP/2 Direct)

  ``h2c`` and ``http/1.1``.

Requirements
------------

The following package is required to build the libnghttp2 library:

* pkg-config >= 0.20

To build the documentation, you need to install:

* sphinx (http://sphinx-doc.org/)

If you need libnghttp2 (C library) only, then the above packages are
all you need.  Use ``--enable-lib-only`` to ensure that only
libnghttp2 is built.  This avoids potential build error related to
building bundled applications.

To build and run the application programs (``nghttp``, ``nghttpd``,
``nghttpx`` and ``h2load``) in the ``src`` directory, the following packages
are required:

* OpenSSL >= 1.1.1; or wolfSSL >= 5.7.0; or LibreSSL >= 3.8.1; or
  aws-lc >= 1.19.0; or BoringSSL
* libev >= 4.11
* zlib >= 1.2.3
* libc-ares >= 1.7.5

To enable ``-a`` option (getting linked assets from the downloaded
resource) in ``nghttp``, the following package is required:

* libxml2 >= 2.6.26

To enable systemd support in nghttpx, the following package is
required:

* libsystemd-dev >= 209

The HPACK tools require the following package:

* jansson >= 2.5

To build sources under the examples directory, libevent is required:

* libevent-openssl >= 2.0.8

To mitigate heap fragmentation in long running server programs
(``nghttpd`` and ``nghttpx``), jemalloc is recommended:

* jemalloc

  .. note::

     Alpine Linux currently does not support malloc replacement
     due to musl limitations. See details in issue `#762 <https://github.com/nghttp2/nghttp2/issues/762>`_.

For BoringSSL or aws-lc build, to enable :rfc:`8879` TLS Certificate
Compression in applications, the following library is required:

* libbrotli-dev >= 1.0.9

To enable mruby support for nghttpx, `mruby
<https://github.com/mruby/mruby>`_ is required.  We need to build
mruby with C++ ABI explicitly turned on, and probably need other
mrgems, mruby is managed by git submodule under third-party/mruby
directory.  Currently, mruby support for nghttpx is disabled by
default.  To enable mruby support, use ``--with-mruby`` configure
option.  Note that at the time of this writing, libmruby-dev and mruby
packages in Debian/Ubuntu are not usable for nghttp2, since they do
not enable C++ ABI.  To build mruby, the following packages are
required:

* ruby
* bison

nghttpx supports `neverbleed <https://github.com/h2o/neverbleed>`_,
privilege separation engine for OpenSSL.  In short, it minimizes the
risk of private key leakage when serious bug like Heartbleed is
exploited.  The neverbleed is disabled by default.  To enable it, use
``--with-neverbleed`` configure option.

To enable the experimental HTTP/3 support for h2load and nghttpx, the
following libraries are required:

* `OpenSSL with QUIC support
  <https://github.com/quictls/openssl/tree/OpenSSL_1_1_1w+quic>`_; or
  wolfSSL; or LibreSSL (does not support 0RTT); or aws-lc; or
  `BoringSSL <https://boringssl.googlesource.com/boringssl/>`_ (commit
  e13f7e2ff5432205f09b4679c8a7715f1c130372)
* `ngtcp2 <https://github.com/ngtcp2/ngtcp2>`_ >= 1.4.0
* `nghttp3 <https://github.com/ngtcp2/nghttp3>`_ >= 1.1.0

Use ``--enable-http3`` configure option to enable HTTP/3 feature for
h2load and nghttpx.

In order to build optional eBPF program to direct an incoming QUIC UDP
datagram to a correct socket for nghttpx, the following libraries are
required:

* libbpf-dev >= 0.7.0

Use ``--with-libbpf`` configure option to build eBPF program.
libelf-dev is needed to build libbpf.

For Ubuntu 20.04, you can build libbpf from `the source code
<https://github.com/libbpf/libbpf/releases>`_.  nghttpx requires eBPF
program for reloading its configuration and hot swapping its
executable.

Compiling libnghttp2 C source code requires a C99 compiler.  gcc 4.8
is known to be adequate.  In order to compile the C++ source code,
C++20 compliant compiler is required.  At least g++ >= 12 and
clang++ >= 15 are known to work.

.. note::

   To enable mruby support in nghttpx, and use ``--with-mruby``
   configure option.

.. note::

   Mac OS X users may need the ``--disable-threads`` configure option to
   disable multi-threading in nghttpd, nghttpx and h2load to prevent
   them from crashing. A patch is welcome to make multi threading work
   on Mac OS X platform.

.. note::

   To compile the associated applications (nghttp, nghttpd, nghttpx
   and h2load), you must use the ``--enable-app`` configure option and
   ensure that the specified requirements above are met.  Normally,
   configure script checks required dependencies to build these
   applications, and enable ``--enable-app`` automatically, so you
   don't have to use it explicitly.  But if you found that
   applications were not built, then using ``--enable-app`` may find
   that cause, such as the missing dependency.

.. note::

   In order to detect third party libraries, pkg-config is used
   (however we don't use pkg-config for some libraries (e.g., libev)).
   By default, pkg-config searches ``*.pc`` file in the standard
   locations (e.g., /usr/lib/pkgconfig).  If it is necessary to use
   ``*.pc`` file in the custom location, specify paths to
   ``PKG_CONFIG_PATH`` environment variable, and pass it to configure
   script, like so:

   .. code-block:: text

       $ ./configure PKG_CONFIG_PATH=/path/to/pkgconfig

   For pkg-config managed libraries, ``*_CFLAG`` and ``*_LIBS``
   environment variables are defined (e.g., ``OPENSSL_CFLAGS``,
   ``OPENSSL_LIBS``).  Specifying non-empty string to these variables
   completely overrides pkg-config.  In other words, if they are
   specified, pkg-config is not used for detection, and user is
   responsible to specify the correct values to these variables.  For
   complete list of these variables, run ``./configure -h``.

If you are using Ubuntu 22.04 LTS, run the following to install the
required packages:

.. code-block:: text

    sudo apt-get install g++ clang make binutils autoconf automake \
      autotools-dev libtool pkg-config \
      zlib1g-dev libssl-dev libxml2-dev libev-dev \
      libevent-dev libjansson-dev \
      libc-ares-dev libjemalloc-dev libsystemd-dev \
      ruby-dev bison libelf-dev

Building nghttp2 from release tar archive
-----------------------------------------

The nghttp2 project regularly releases tar archives which includes
nghttp2 source code, and generated build files.  They can be
downloaded from `Releases
<https://github.com/nghttp2/nghttp2/releases>`_ page.

Building nghttp2 from git requires autotools development packages.
Building from tar archives does not require them, and thus it is much
easier.  The usual build step is as follows:

.. code-block:: text

    $ tar xf nghttp2-X.Y.Z.tar.bz2
    $ cd nghttp2-X.Y.Z
    $ ./configure
    $ make

Building from git
-----------------

Building from git is easy, but please be sure that at least autoconf 2.68 is
used:

.. code-block:: text

    $ git submodule update --init
    $ autoreconf -i
    $ automake
    $ autoconf
    $ ./configure
    $ make

Notes for building on Windows (MSVC)
------------------------------------

The easiest way to build native Windows nghttp2 dll is use `cmake
<https://cmake.org/>`_.  The free version of `Visual C++ Build Tools
<http://landinghub.visualstudio.com/visual-cpp-build-tools>`_ works
fine.

1. Install cmake for windows
2. Open "Visual C++ ... Native Build Tool Command Prompt", and inside
   nghttp2 directly, run ``cmake``.
3. Then run ``cmake --build`` to build library.
4. nghttp2.dll, nghttp2.lib, nghttp2.exp are placed under lib directory.

Note that the above steps most likely produce nghttp2 library only.
No bundled applications are compiled.

Notes for building on Windows (Mingw/Cygwin)
--------------------------------------------

Under Mingw environment, you can only compile the library, it's
``libnghttp2-X.dll`` and ``libnghttp2.a``.

If you want to compile the applications(``h2load``, ``nghttp``,
``nghttpx``, ``nghttpd``), you need to use the Cygwin environment.

Under Cygwin environment, to compile the applications you need to
compile and install the libev first.

Secondly, you need to undefine the macro ``__STRICT_ANSI__``, if you
not, the functions ``fdopen``, ``fileno`` and ``strptime`` will not
available.

the sample command like this:

.. code-block:: text

    $ export CFLAGS="-U__STRICT_ANSI__ -I$libev_PREFIX/include -L$libev_PREFIX/lib"
    $ export CXXFLAGS=$CFLAGS
    $ ./configure
    $ make

If you want to compile the applications under ``examples/``, you need
to remove or rename the ``event.h`` from libev's installation, because
it conflicts with libevent's installation.

Notes for installation on Linux systems
--------------------------------------------
After installing nghttp2 tool suite with ``make install`` one might experience a similar error:

.. code-block:: text

    nghttpx: error while loading shared libraries: libnghttp2.so.14: cannot open shared object file: No such file or directory

This means that the tool is unable to locate the ``libnghttp2.so`` shared library.

To update the shared library cache run ``sudo ldconfig``.

Building the documentation
--------------------------

.. note::

   Documentation is still incomplete.

To build the documentation, run:

.. code-block:: text

    $ make html

The documents will be generated under ``doc/manual/html/``.

The generated documents will not be installed with ``make install``.

The online documentation is available at
https://nghttp2.org/documentation/

Build HTTP/3 enabled h2load and nghttpx
---------------------------------------

To build h2load and nghttpx with HTTP/3 feature enabled, run the
configure script with ``--enable-http3``.

For nghttpx to reload configurations and swapping its executable while
gracefully terminating old worker processes, eBPF is required.  Run
the configure script with ``--enable-http3 --with-libbpf`` to build
eBPF program.  The QUIC keying material must be set with
``--frontend-quic-secret-file`` in order to keep the existing
connections alive during reload.

The detailed steps to build HTTP/3 enabled h2load and nghttpx follow.

Build aws-lc:

.. code-block:: text

   $ git clone --depth 1 -b v1.34.2 https://github.com/aws/aws-lc
   $ cd aws-lc
   $ cmake -B build -DDISABLE_GO=ON --install-prefix=$PWD/opt
   $ make -j$(nproc) -C build
   $ cmake --install build
   $ cd ..

Build nghttp3:

.. code-block:: text

   $ git clone --depth 1 -b v1.5.0 https://github.com/ngtcp2/nghttp3
   $ cd nghttp3
   $ git submodule update --init --depth 1
   $ autoreconf -i
   $ ./configure --prefix=$PWD/build --enable-lib-only
   $ make -j$(nproc)
   $ make install
   $ cd ..

Build ngtcp2:

.. code-block:: text

   $ git clone --depth 1 -b v1.7.0 https://github.com/ngtcp2/ngtcp2
   $ cd ngtcp2
   $ git submodule update --init --depth 1
   $ autoreconf -i
   $ ./configure --prefix=$PWD/build --enable-lib-only --with-boringssl \
         BORINGSSL_CFLAGS="-I$PWD/../aws-lc/opt/include" \
         BORINGSSL_LIBS="-L$PWD/../aws-lc/opt/lib -lssl -lcrypto"
   $ make -j$(nproc)
   $ make install
   $ cd ..

If your Linux distribution does not have libbpf-dev >= 0.7.0, build
from source:

.. code-block:: text

   $ git clone --depth 1 -b v1.4.5 https://github.com/libbpf/libbpf
   $ cd libbpf
   $ PREFIX=$PWD/build make -C src install
   $ cd ..

Build nghttp2:

.. code-block:: text

   $ git clone https://github.com/nghttp2/nghttp2
   $ cd nghttp2
   $ git submodule update --init
   $ autoreconf -i
   $ ./configure --with-mruby --enable-http3 --with-libbpf \
         CC=clang-15 CXX=clang++-15 \
         PKG_CONFIG_PATH="$PWD/../aws-lc/opt/lib/pkgconfig:$PWD/../nghttp3/build/lib/pkgconfig:$PWD/../ngtcp2/build/lib/pkgconfig:$PWD/../libbpf/build/lib64/pkgconfig" \
         LDFLAGS="$LDFLAGS -Wl,-rpath,$PWD/../aws-lc/opt/lib -Wl,-rpath,$PWD/../libbpf/build/lib64"
   $ make -j$(nproc)

The eBPF program ``reuseport_kern.o`` should be found under bpf
directory.  Pass ``--quic-bpf-program-file=bpf/reuseport_kern.o``
option to nghttpx to load it.  See also `HTTP/3 section in nghttpx -
HTTP/2 proxy - HOW-TO
<https://nghttp2.org/documentation/nghttpx-howto.html#http-3>`_.

Unit tests
----------

Unit tests are done by simply running ``make check``.

Integration tests
-----------------

We have the integration tests for the nghttpx proxy server.  The tests are
written in the `Go programming language <http://golang.org/>`_ and uses
its testing framework.  We depend on the following libraries:

* golang.org/x/net/http2
* golang.org/x/net/websocket
* https://github.com/tatsuhiro-t/go-nghttp2

Go modules will download these dependencies automatically.

To run the tests, run the following command under
``integration-tests`` directory:

.. code-block:: text

    $ make it

Inside the tests, we use port 3009 to run the test subject server.

Migration from v0.7.15 or earlier
---------------------------------

nghttp2 v1.0.0 introduced several backward incompatible changes.  In
this section, we describe these changes and how to migrate to v1.0.0.

ALPN protocol ID is now ``h2`` and ``h2c``
++++++++++++++++++++++++++++++++++++++++++

Previously we announced ``h2-14`` and ``h2c-14``.  v1.0.0 implements
final protocol version, and we changed ALPN ID to ``h2`` and ``h2c``.
The macros ``NGHTTP2_PROTO_VERSION_ID``,
``NGHTTP2_PROTO_VERSION_ID_LEN``,
``NGHTTP2_CLEARTEXT_PROTO_VERSION_ID``, and
``NGHTTP2_CLEARTEXT_PROTO_VERSION_ID_LEN`` have been updated to
reflect this change.

Basically, existing applications do not have to do anything, just
recompiling is enough for this change.

Use word "client magic" where we use "client connection preface"
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

We use "client connection preface" to mean first 24 bytes of client
connection preface.  This is technically not correct, since client
connection preface is composed of 24 bytes client magic byte string
followed by SETTINGS frame.  For clarification, we call "client magic"
for this 24 bytes byte string and updated API.

* ``NGHTTP2_CLIENT_CONNECTION_PREFACE`` was replaced with
  ``NGHTTP2_CLIENT_MAGIC``.
* ``NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN`` was replaced with
  ``NGHTTP2_CLIENT_MAGIC_LEN``.
* ``NGHTTP2_BAD_PREFACE`` was renamed as ``NGHTTP2_BAD_CLIENT_MAGIC``

The already deprecated ``NGHTTP2_CLIENT_CONNECTION_HEADER`` and
``NGHTTP2_CLIENT_CONNECTION_HEADER_LEN`` were removed.

If application uses these macros, just replace old ones with new ones.
Since v1.0.0, client magic is sent by library (see next subsection),
so client application may just remove these macro use.

Client magic is sent by library
+++++++++++++++++++++++++++++++

Previously nghttp2 library did not send client magic, which is first
24 bytes byte string of client connection preface, and client
applications have to send it by themselves.  Since v1.0.0, client
magic is sent by library via first call of ``nghttp2_session_send()``
or ``nghttp2_session_mem_send2()``.

The client applications which send client magic must remove the
relevant code.

Remove HTTP Alternative Services (Alt-Svc) related code
+++++++++++++++++++++++++++++++++++++++++++++++++++++++

Alt-Svc specification is not finalized yet.  To make our API stable,
we have decided to remove all Alt-Svc related API from nghttp2.

* ``NGHTTP2_EXT_ALTSVC`` was removed.
* ``nghttp2_ext_altsvc`` was removed.

We have already removed the functionality of Alt-Svc in v0.7 series
and they have been essentially noop.  The application using these
macro and struct, remove those lines.

Use nghttp2_error in nghttp2_on_invalid_frame_recv_callback
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Previously ``nghttp2_on_invalid_frame_recv_cb_called`` took the
``error_code``, defined in ``nghttp2_error_code``, as parameter.  But
they are not detailed enough to debug.  Therefore, we decided to use
more detailed ``nghttp2_error`` values instead.

The application using this callback should update the callback
signature.  If it treats ``error_code`` as HTTP/2 error code, update
the code so that it is treated as ``nghttp2_error``.

Receive client magic by default
+++++++++++++++++++++++++++++++

Previously nghttp2 did not process client magic (24 bytes byte
string).  To make it deal with it, we had to use
``nghttp2_option_set_recv_client_preface()``.  Since v1.0.0, nghttp2
processes client magic by default and
``nghttp2_option_set_recv_client_preface()`` was removed.

Some application may want to disable this behaviour, so we added
``nghttp2_option_set_no_recv_client_magic()`` to achieve this.

The application using ``nghttp2_option_set_recv_client_preface()``
with nonzero value, just remove it.

The application using ``nghttp2_option_set_recv_client_preface()``
with zero value or not using it must use
``nghttp2_option_set_no_recv_client_magic()`` with nonzero value.

Client, Server and Proxy programs
---------------------------------

The ``src`` directory contains the HTTP/2 client, server and proxy programs.

nghttp - client
+++++++++++++++

``nghttp`` is a HTTP/2 client.  It can connect to the HTTP/2 server
with prior knowledge, HTTP Upgrade and ALPN TLS extension.

It has verbose output mode for framing information.  Here is sample
output from ``nghttp`` client:

.. code-block:: text

    $ nghttp -nv https://nghttp2.org
    [  0.190] Connected
    The negotiated protocol: h2
    [  0.212] recv SETTINGS frame <length=12, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
    [  0.212] send SETTINGS frame <length=12, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
    [  0.212] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=3>
	      (dep_stream_id=0, weight=201, exclusive=0)
    [  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=5>
	      (dep_stream_id=0, weight=101, exclusive=0)
    [  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=7>
	      (dep_stream_id=0, weight=1, exclusive=0)
    [  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=9>
	      (dep_stream_id=7, weight=1, exclusive=0)
    [  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=11>
	      (dep_stream_id=3, weight=1, exclusive=0)
    [  0.212] send HEADERS frame <length=39, flags=0x25, stream_id=13>
	      ; END_STREAM | END_HEADERS | PRIORITY
	      (padlen=0, dep_stream_id=11, weight=16, exclusive=0)
	      ; Open new stream
	      :method: GET
	      :path: /
	      :scheme: https
	      :authority: nghttp2.org
	      accept: */*
	      accept-encoding: gzip, deflate
	      user-agent: nghttp2/1.0.1-DEV
    [  0.221] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [  0.221] recv (stream_id=13) :method: GET
    [  0.221] recv (stream_id=13) :scheme: https
    [  0.221] recv (stream_id=13) :path: /stylesheets/screen.css
    [  0.221] recv (stream_id=13) :authority: nghttp2.org
    [  0.221] recv (stream_id=13) accept-encoding: gzip, deflate
    [  0.222] recv (stream_id=13) user-agent: nghttp2/1.0.1-DEV
    [  0.222] recv PUSH_PROMISE frame <length=50, flags=0x04, stream_id=13>
	      ; END_HEADERS
	      (padlen=0, promised_stream_id=2)
    [  0.222] recv (stream_id=13) :status: 200
    [  0.222] recv (stream_id=13) date: Thu, 21 May 2015 16:38:14 GMT
    [  0.222] recv (stream_id=13) content-type: text/html
    [  0.222] recv (stream_id=13) last-modified: Fri, 15 May 2015 15:38:06 GMT
    [  0.222] recv (stream_id=13) etag: W/"555612de-19f6"
    [  0.222] recv (stream_id=13) link: </stylesheets/screen.css>; rel=preload; as=stylesheet
    [  0.222] recv (stream_id=13) content-encoding: gzip
    [  0.222] recv (stream_id=13) server: nghttpx nghttp2/1.0.1-DEV
    [  0.222] recv (stream_id=13) via: 1.1 nghttpx
    [  0.222] recv (stream_id=13) strict-transport-security: max-age=31536000
    [  0.222] recv HEADERS frame <length=166, flags=0x04, stream_id=13>
	      ; END_HEADERS
	      (padlen=0)
	      ; First response header
    [  0.222] recv DATA frame <length=2601, flags=0x01, stream_id=13>
	      ; END_STREAM
    [  0.222] recv (stream_id=2) :status: 200
    [  0.222] recv (stream_id=2) date: Thu, 21 May 2015 16:38:14 GMT
    [  0.222] recv (stream_id=2) content-type: text/css
    [  0.222] recv (stream_id=2) last-modified: Fri, 15 May 2015 15:38:06 GMT
    [  0.222] recv (stream_id=2) etag: W/"555612de-9845"
    [  0.222] recv (stream_id=2) content-encoding: gzip
    [  0.222] recv (stream_id=2) server: nghttpx nghttp2/1.0.1-DEV
    [  0.222] recv (stream_id=2) via: 1.1 nghttpx
    [  0.222] recv (stream_id=2) strict-transport-security: max-age=31536000
    [  0.222] recv HEADERS frame <length=32, flags=0x04, stream_id=2>
	      ; END_HEADERS
	      (padlen=0)
	      ; First push response header
    [  0.228] recv DATA frame <length=8715, flags=0x01, stream_id=2>
	      ; END_STREAM
    [  0.228] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
	      (last_stream_id=2, error_code=NO_ERROR(0x00), opaque_data(0)=[])

The HTTP Upgrade is performed like so:

.. code-block:: text

    $ nghttp -nvu http://nghttp2.org
    [  0.011] Connected
    [  0.011] HTTP Upgrade request
    GET / HTTP/1.1
    Host: nghttp2.org
    Connection: Upgrade, HTTP2-Settings
    Upgrade: h2c
    HTTP2-Settings: AAMAAABkAAQAAP__
    Accept: */*
    User-Agent: nghttp2/1.0.1-DEV


    [  0.018] HTTP Upgrade response
    HTTP/1.1 101 Switching Protocols
    Connection: Upgrade
    Upgrade: h2c


    [  0.018] HTTP Upgrade success
    [  0.018] recv SETTINGS frame <length=12, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
    [  0.018] send SETTINGS frame <length=12, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
    [  0.018] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=3>
	      (dep_stream_id=0, weight=201, exclusive=0)
    [  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=5>
	      (dep_stream_id=0, weight=101, exclusive=0)
    [  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=7>
	      (dep_stream_id=0, weight=1, exclusive=0)
    [  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=9>
	      (dep_stream_id=7, weight=1, exclusive=0)
    [  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=11>
	      (dep_stream_id=3, weight=1, exclusive=0)
    [  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=1>
	      (dep_stream_id=11, weight=16, exclusive=0)
    [  0.019] recv (stream_id=1) :method: GET
    [  0.019] recv (stream_id=1) :scheme: http
    [  0.019] recv (stream_id=1) :path: /stylesheets/screen.css
    [  0.019] recv (stream_id=1) host: nghttp2.org
    [  0.019] recv (stream_id=1) user-agent: nghttp2/1.0.1-DEV
    [  0.019] recv PUSH_PROMISE frame <length=49, flags=0x04, stream_id=1>
	      ; END_HEADERS
	      (padlen=0, promised_stream_id=2)
    [  0.019] recv (stream_id=1) :status: 200
    [  0.019] recv (stream_id=1) date: Thu, 21 May 2015 16:39:16 GMT
    [  0.019] recv (stream_id=1) content-type: text/html
    [  0.019] recv (stream_id=1) content-length: 6646
    [  0.019] recv (stream_id=1) last-modified: Fri, 15 May 2015 15:38:06 GMT
    [  0.019] recv (stream_id=1) etag: "555612de-19f6"
    [  0.019] recv (stream_id=1) link: </stylesheets/screen.css>; rel=preload; as=stylesheet
    [  0.019] recv (stream_id=1) accept-ranges: bytes
    [  0.019] recv (stream_id=1) server: nghttpx nghttp2/1.0.1-DEV
    [  0.019] recv (stream_id=1) via: 1.1 nghttpx
    [  0.019] recv HEADERS frame <length=157, flags=0x04, stream_id=1>
	      ; END_HEADERS
	      (padlen=0)
	      ; First response header
    [  0.019] recv DATA frame <length=6646, flags=0x01, stream_id=1>
	      ; END_STREAM
    [  0.019] recv (stream_id=2) :status: 200
    [  0.019] recv (stream_id=2) date: Thu, 21 May 2015 16:39:16 GMT
    [  0.019] recv (stream_id=2) content-type: text/css
    [  0.019] recv (stream_id=2) content-length: 38981
    [  0.019] recv (stream_id=2) last-modified: Fri, 15 May 2015 15:38:06 GMT
    [  0.019] recv (stream_id=2) etag: "555612de-9845"
    [  0.019] recv (stream_id=2) accept-ranges: bytes
    [  0.019] recv (stream_id=2) server: nghttpx nghttp2/1.0.1-DEV
    [  0.019] recv (stream_id=2) via: 1.1 nghttpx
    [  0.019] recv HEADERS frame <length=36, flags=0x04, stream_id=2>
	      ; END_HEADERS
	      (padlen=0)
	      ; First push response header
    [  0.026] recv DATA frame <length=16384, flags=0x00, stream_id=2>
    [  0.027] recv DATA frame <length=7952, flags=0x00, stream_id=2>
    [  0.027] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
	      (window_size_increment=33343)
    [  0.032] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=2>
	      (window_size_increment=33707)
    [  0.032] recv DATA frame <length=14645, flags=0x01, stream_id=2>
	      ; END_STREAM
    [  0.032] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [  0.032] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
	      (last_stream_id=2, error_code=NO_ERROR(0x00), opaque_data(0)=[])

Using the ``-s`` option, ``nghttp`` prints out some timing information for
requests, sorted by completion time:

.. code-block:: text

    $ nghttp -nas https://nghttp2.org/
    ***** Statistics *****

    Request timing:
      responseEnd: the  time  when  last  byte of  response  was  received
                   relative to connectEnd
     requestStart: the time  just before  first byte  of request  was sent
                   relative  to connectEnd.   If  '*' is  shown, this  was
                   pushed by server.
          process: responseEnd - requestStart
             code: HTTP status code
             size: number  of  bytes  received as  response  body  without
                   inflation.
              URI: request URI

    see http://www.w3.org/TR/resource-timing/#processing-model

    sorted by 'complete'

    id  responseEnd requestStart  process code size request path
     13    +37.19ms       +280us  36.91ms  200   2K /
      2    +72.65ms *   +36.38ms  36.26ms  200   8K /stylesheets/screen.css
     17    +77.43ms     +38.67ms  38.75ms  200   3K /javascripts/octopress.js
     15    +78.12ms     +38.66ms  39.46ms  200   3K /javascripts/modernizr-2.0.js

Using the ``-r`` option, ``nghttp`` writes more detailed timing data to
the given file in HAR format.

nghttpd - server
++++++++++++++++

``nghttpd`` is a multi-threaded static web server.

By default, it uses SSL/TLS connection.  Use ``--no-tls`` option to
disable it.

``nghttpd`` only accepts HTTP/2 connections via ALPN or direct HTTP/2
connections.  No HTTP Upgrade is supported.

The ``-p`` option allows users to configure server push.

Just like ``nghttp``, it has a verbose output mode for framing
information.  Here is sample output from ``nghttpd``:

.. code-block:: text

    $ nghttpd --no-tls -v 8080
    IPv4: listen 0.0.0.0:8080
    IPv6: listen :::8080
    [id=1] [  1.521] send SETTINGS frame <length=6, flags=0x00, stream_id=0>
              (niv=1)
              [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
    [id=1] [  1.521] recv SETTINGS frame <length=12, flags=0x00, stream_id=0>
              (niv=2)
              [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
              [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
    [id=1] [  1.521] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
              ; ACK
              (niv=0)
    [id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=3>
              (dep_stream_id=0, weight=201, exclusive=0)
    [id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=5>
              (dep_stream_id=0, weight=101, exclusive=0)
    [id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=7>
              (dep_stream_id=0, weight=1, exclusive=0)
    [id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=9>
              (dep_stream_id=7, weight=1, exclusive=0)
    [id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=11>
              (dep_stream_id=3, weight=1, exclusive=0)
    [id=1] [  1.521] recv (stream_id=13) :method: GET
    [id=1] [  1.521] recv (stream_id=13) :path: /
    [id=1] [  1.521] recv (stream_id=13) :scheme: http
    [id=1] [  1.521] recv (stream_id=13) :authority: localhost:8080
    [id=1] [  1.521] recv (stream_id=13) accept: */*
    [id=1] [  1.521] recv (stream_id=13) accept-encoding: gzip, deflate
    [id=1] [  1.521] recv (stream_id=13) user-agent: nghttp2/1.0.0-DEV
    [id=1] [  1.521] recv HEADERS frame <length=41, flags=0x25, stream_id=13>
              ; END_STREAM | END_HEADERS | PRIORITY
              (padlen=0, dep_stream_id=11, weight=16, exclusive=0)
              ; Open new stream
    [id=1] [  1.521] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
              ; ACK
              (niv=0)
    [id=1] [  1.521] send HEADERS frame <length=86, flags=0x04, stream_id=13>
              ; END_HEADERS
              (padlen=0)
              ; First response header
              :status: 200
              server: nghttpd nghttp2/1.0.0-DEV
              content-length: 10
              cache-control: max-age=3600
              date: Fri, 15 May 2015 14:49:04 GMT
              last-modified: Tue, 30 Sep 2014 12:40:52 GMT
    [id=1] [  1.522] send DATA frame <length=10, flags=0x01, stream_id=13>
              ; END_STREAM
    [id=1] [  1.522] stream_id=13 closed
    [id=1] [  1.522] recv GOAWAY frame <length=8, flags=0x00, stream_id=0>
              (last_stream_id=0, error_code=NO_ERROR(0x00), opaque_data(0)=[])
    [id=1] [  1.522] closed

nghttpx - proxy
+++++++++++++++

``nghttpx`` is a multi-threaded reverse proxy for HTTP/3, HTTP/2, and
HTTP/1.1, and powers http://nghttp2.org and supports HTTP/2 server
push.

We reworked ``nghttpx`` command-line interface, and as a result, there
are several incompatibles from 1.8.0 or earlier.  This is necessary to
extend its capability, and secure the further feature enhancements in
the future release.  Please read `Migration from nghttpx v1.8.0 or
earlier
<https://nghttp2.org/documentation/nghttpx-howto.html#migration-from-nghttpx-v1-8-0-or-earlier>`_
to know how to migrate from earlier releases.

``nghttpx`` implements `important performance-oriented features
<https://istlsfastyet.com/#server-performance>`_ in TLS, such as
session IDs, session tickets (with automatic key rotation), OCSP
stapling, dynamic record sizing, ALPN, forward secrecy and HTTP/2.
``nghttpx`` also offers the functionality to share session cache and
ticket keys among multiple ``nghttpx`` instances via memcached.

``nghttpx`` has 2 operation modes:

================== ======================== ================ =============
Mode option        Frontend                 Backend          Note
================== ======================== ================ =============
default mode       HTTP/3, HTTP/2, HTTP/1.1 HTTP/1.1, HTTP/2 Reverse proxy
``--http2-proxy``  HTTP/3, HTTP/2, HTTP/1.1 HTTP/1.1, HTTP/2 Forward proxy
================== ======================== ================ =============

The interesting mode at the moment is the default mode.  It works like
a reverse proxy and listens for HTTP/3, HTTP/2, and HTTP/1.1 and can
be deployed as a SSL/TLS terminator for existing web server.

In all modes, the frontend connections are encrypted by SSL/TLS by
default.  To disable encryption, use the ``no-tls`` keyword in
``--frontend`` option.  If encryption is disabled, incoming HTTP/1.1
connections can be upgraded to HTTP/2 through HTTP Upgrade.  On the
other hard, backend connections are not encrypted by default.  To
encrypt backend connections, use ``tls`` keyword in ``--backend``
option.

``nghttpx`` supports a configuration file.  See the ``--conf`` option and
sample configuration file ``nghttpx.conf.sample``.

In the default mode, ``nghttpx`` works as reverse proxy to the backend
server:

.. code-block:: text

    Client <-- (HTTP/3, HTTP/2, HTTP/1.1) --> nghttpx <-- (HTTP/1.1, HTTP/2) --> Web Server
                                            [reverse proxy]

With the ``--http2-proxy`` option, it works as forward proxy, and it
is so called secure HTTP/2 proxy:

.. code-block:: text

    Client <-- (HTTP/3, HTTP/2, HTTP/1.1) --> nghttpx <-- (HTTP/1.1) --> Proxy
                                             [secure proxy]          (e.g., Squid, ATS)

The ``Client`` in the above example needs to be configured to use
``nghttpx`` as secure proxy.

At the time of this writing, both Chrome and Firefox support secure
HTTP/2 proxy.  One way to configure Chrome to use a secure proxy is to
create a proxy.pac script like this:

.. code-block:: javascript

    function FindProxyForURL(url, host) {
        return "HTTPS SERVERADDR:PORT";
    }

``SERVERADDR`` and ``PORT`` is the hostname/address and port of the
machine nghttpx is running on.  Please note that Chrome requires a valid
certificate for secure proxy.

Then run Chrome with the following arguments:

.. code-block:: text

    $ google-chrome --proxy-pac-url=file:///path/to/proxy.pac --use-npn

The backend HTTP/2 connections can be tunneled through an HTTP proxy.
The proxy is specified using ``--backend-http-proxy-uri``.  The
following figure illustrates how nghttpx talks to the outside HTTP/2
proxy through an HTTP proxy:

.. code-block:: text

    Client <-- (HTTP/3, HTTP/2, HTTP/1.1) --> nghttpx <-- (HTTP/2) --

            --===================---> HTTP/2 Proxy
              (HTTP proxy tunnel)     (e.g., nghttpx -s)

Benchmarking tool
-----------------

The ``h2load`` program is a benchmarking tool for HTTP/3, HTTP/2, and
HTTP/1.1.  The UI of ``h2load`` is heavily inspired by ``weighttp``
(https://github.com/lighttpd/weighttp).  The typical usage is as
follows:

.. code-block:: text

    $ h2load -n100000 -c100 -m100 https://localhost:8443/
    starting benchmark...
    spawning thread #0: 100 concurrent clients, 100000 total requests
    Protocol: TLSv1.2
    Cipher: ECDHE-RSA-AES128-GCM-SHA256
    Server Temp Key: ECDH P-256 256 bits
    progress: 10% done
    progress: 20% done
    progress: 30% done
    progress: 40% done
    progress: 50% done
    progress: 60% done
    progress: 70% done
    progress: 80% done
    progress: 90% done
    progress: 100% done

    finished in 771.26ms, 129658 req/s, 4.71MB/s
    requests: 100000 total, 100000 started, 100000 done, 100000 succeeded, 0 failed, 0 errored
    status codes: 100000 2xx, 0 3xx, 0 4xx, 0 5xx
    traffic: 3812300 bytes total, 1009900 bytes headers, 1000000 bytes data
                         min         max         mean         sd        +/- sd
    time for request:    25.12ms    124.55ms     51.07ms     15.36ms    84.87%
    time for connect:   208.94ms    254.67ms    241.38ms      7.95ms    63.00%
    time to 1st byte:   209.11ms    254.80ms    241.51ms      7.94ms    63.00%

The above example issued total 100,000 requests, using 100 concurrent
clients (in other words, 100 HTTP/2 sessions), and a maximum of 100 streams
per client.  With the ``-t`` option, ``h2load`` will use multiple native
threads to avoid saturating a single core on client side.

.. warning::

   **Don't use this tool against publicly available servers.** That is
   considered a DOS attack.  Please only use it against your private
   servers.

If the experimental HTTP/3 is enabled, h2load can send requests to
HTTP/3 server.  To do this, specify ``h3`` to ``--alpn-list`` option
like so:

.. code-block:: text

    $ h2load --alpn-list h3 https://127.0.0.1:4433

For nghttp2 v1.58 or earlier, use ``--npn-list`` instead of
``--alpn-list``.

HPACK tools
-----------

The ``src`` directory contains the HPACK tools.  The ``deflatehd`` program is a
command-line header compression tool.  The ``inflatehd`` program is a
command-line header decompression tool.  Both tools read input from
stdin and write output to stdout.  Errors are written to stderr.
They take JSON as input and output.  We  (mostly) use the same JSON data
format described at https://github.com/http2jp/hpack-test-case.

deflatehd - header compressor
+++++++++++++++++++++++++++++

The ``deflatehd`` program reads JSON data or HTTP/1-style header fields from
stdin and outputs compressed header block in JSON.

For the JSON input, the root JSON object must include a ``cases`` key.
Its value has to include the sequence of input header set.  They share
the same compression context and are processed in the order they
appear.  Each item in the sequence is a JSON object and it must
include a ``headers`` key.  Its value is an array of JSON objects,
which includes exactly one name/value pair.

Example:

.. code-block:: json

    {
      "cases":
      [
        {
          "headers": [
            { ":method": "GET" },
            { ":path": "/" }
          ]
        },
        {
          "headers": [
            { ":method": "POST" },
            { ":path": "/" }
          ]
        }
      ]
    }


With the ``-t`` option, the program can accept more familiar HTTP/1 style
header field blocks.  Each header set is delimited by an empty line:

Example:

.. code-block:: text

    :method: GET
    :scheme: https
    :path: /

    :method: POST
    user-agent: nghttp2

The output is in JSON object.  It should include a ``cases`` key and its
value is an array of JSON objects, which has at least the following keys:

seq
    The index of header set in the input.

input_length
    The sum of the length of the name/value pairs in the input.

output_length
    The length of the compressed header block.

percentage_of_original_size
    ``output_length`` / ``input_length`` * 100

wire
    The compressed header block as a hex string.

headers
    The input header set.

header_table_size
    The header table size adjusted before deflating the header set.

Examples:

.. code-block:: json

    {
      "cases":
      [
        {
          "seq": 0,
          "input_length": 66,
          "output_length": 20,
          "percentage_of_original_size": 30.303030303030305,
          "wire": "01881f3468e5891afcbf83868a3d856659c62e3f",
          "headers": [
            {
              ":authority": "example.org"
            },
            {
              ":method": "GET"
            },
            {
              ":path": "/"
            },
            {
              ":scheme": "https"
            },
            {
              "user-agent": "nghttp2"
            }
          ],
          "header_table_size": 4096
        }
        ,
        {
          "seq": 1,
          "input_length": 74,
          "output_length": 10,
          "percentage_of_original_size": 13.513513513513514,
          "wire": "88448504252dd5918485",
          "headers": [
            {
              ":authority": "example.org"
            },
            {
              ":method": "POST"
            },
            {
              ":path": "/account"
            },
            {
              ":scheme": "https"
            },
            {
              "user-agent": "nghttp2"
            }
          ],
          "header_table_size": 4096
        }
      ]
    }


The output can be used as the input for ``inflatehd`` and
``deflatehd``.

With the ``-d`` option, the extra ``header_table`` key is added and its
associated value includes the state of dynamic header table after the
corresponding header set was processed.  The value includes at least
the following keys:

entries
    The entry in the header table.  If ``referenced`` is ``true``, it
    is in the reference set.  The ``size`` includes the overhead (32
    bytes).  The ``index`` corresponds to the index of header table.
    The ``name`` is the header field name and the ``value`` is the
    header field value.

size
    The sum of the spaces entries occupied, this includes the
    entry overhead.

max_size
    The maximum header table size.

deflate_size
    The sum of the spaces entries occupied within
    ``max_deflate_size``.

max_deflate_size
    The maximum header table size the encoder uses.  This can be smaller
    than ``max_size``.  In this case, the encoder only uses up to first
    ``max_deflate_size`` buffer.  Since the header table size is still
    ``max_size``, the encoder has to keep track of entries outside the
    ``max_deflate_size`` but inside the ``max_size`` and make sure
    that they are no longer referenced.

Example:

.. code-block:: json

    {
      "cases":
      [
        {
          "seq": 0,
          "input_length": 66,
          "output_length": 20,
          "percentage_of_original_size": 30.303030303030305,
          "wire": "01881f3468e5891afcbf83868a3d856659c62e3f",
          "headers": [
            {
              ":authority": "example.org"
            },
            {
              ":method": "GET"
            },
            {
              ":path": "/"
            },
            {
              ":scheme": "https"
            },
            {
              "user-agent": "nghttp2"
            }
          ],
          "header_table_size": 4096,
          "header_table": {
            "entries": [
              {
                "index": 1,
                "name": "user-agent",
                "value": "nghttp2",
                "referenced": true,
                "size": 49
              },
              {
                "index": 2,
                "name": ":scheme",
                "value": "https",
                "referenced": true,
                "size": 44
              },
              {
                "index": 3,
                "name": ":path",
                "value": "/",
                "referenced": true,
                "size": 38
              },
              {
                "index": 4,
                "name": ":method",
                "value": "GET",
                "referenced": true,
                "size": 42
              },
              {
                "index": 5,
                "name": ":authority",
                "value": "example.org",
                "referenced": true,
                "size": 53
              }
            ],
            "size": 226,
            "max_size": 4096,
            "deflate_size": 226,
            "max_deflate_size": 4096
          }
        }
        ,
        {
          "seq": 1,
          "input_length": 74,
          "output_length": 10,
          "percentage_of_original_size": 13.513513513513514,
          "wire": "88448504252dd5918485",
          "headers": [
            {
              ":authority": "example.org"
            },
            {
              ":method": "POST"
            },
            {
              ":path": "/account"
            },
            {
              ":scheme": "https"
            },
            {
              "user-agent": "nghttp2"
            }
          ],
          "header_table_size": 4096,
          "header_table": {
            "entries": [
              {
                "index": 1,
                "name": ":method",
                "value": "POST",
                "referenced": true,
                "size": 43
              },
              {
                "index": 2,
                "name": "user-agent",
                "value": "nghttp2",
                "referenced": true,
                "size": 49
              },
              {
                "index": 3,
                "name": ":scheme",
                "value": "https",
                "referenced": true,
                "size": 44
              },
              {
                "index": 4,
                "name": ":path",
                "value": "/",
                "referenced": false,
                "size": 38
              },
              {
                "index": 5,
                "name": ":method",
                "value": "GET",
                "referenced": false,
                "size": 42
              },
              {
                "index": 6,
                "name": ":authority",
                "value": "example.org",
                "referenced": true,
                "size": 53
              }
            ],
            "size": 269,
            "max_size": 4096,
            "deflate_size": 269,
            "max_deflate_size": 4096
          }
        }
      ]
    }

inflatehd - header decompressor
+++++++++++++++++++++++++++++++

The ``inflatehd`` program reads JSON data from stdin and outputs decompressed
name/value pairs in JSON.

The root JSON object must include the ``cases`` key.  Its value has to
include the sequence of compressed header blocks.  They share the same
compression context and are processed in the order they appear.  Each
item in the sequence is a JSON object and it must have at least a
``wire`` key.  Its value is a compressed header block as a hex string.

Example:

.. code-block:: json

    {
      "cases":
      [
        { "wire": "8285" },
        { "wire": "8583" }
      ]
    }

The output is a JSON object.  It should include a ``cases`` key and its
value is an array of JSON objects, which has at least following keys:

seq
    The index of the header set in the input.

headers
    A JSON array that includes decompressed name/value pairs.

wire
    The compressed header block as a hex string.

header_table_size
    The header table size adjusted before inflating compressed header
    block.

Example:

.. code-block:: json

    {
      "cases":
      [
        {
          "seq": 0,
          "wire": "01881f3468e5891afcbf83868a3d856659c62e3f",
          "headers": [
            {
              ":authority": "example.org"
            },
            {
              ":method": "GET"
            },
            {
              ":path": "/"
            },
            {
              ":scheme": "https"
            },
            {
              "user-agent": "nghttp2"
            }
          ],
          "header_table_size": 4096
        }
        ,
        {
          "seq": 1,
          "wire": "88448504252dd5918485",
          "headers": [
            {
              ":method": "POST"
            },
            {
              ":path": "/account"
            },
            {
              "user-agent": "nghttp2"
            },
            {
              ":scheme": "https"
            },
            {
              ":authority": "example.org"
            }
          ],
          "header_table_size": 4096
        }
      ]
    }

The output can be used as the input for ``deflatehd`` and
``inflatehd``.

With the ``-d`` option, the extra ``header_table`` key is added and its
associated value includes the state of the dynamic header table after the
corresponding header set was processed.  The format is the same as
``deflatehd``.

Contribution
------------

[This text was composed based on 1.2. License section of curl/libcurl
project.]

When contributing with code, you agree to put your changes and new
code under the same license nghttp2 is already using unless stated and
agreed otherwise.

When changing existing source code, do not alter the copyright of
the original file(s).  The copyright will still be owned by the
original creator(s) or those who have been assigned copyright by the
original author(s).

By submitting a patch to the nghttp2 project, you (or your employer, as
the case may be) agree to assign the copyright of your submission to us.
.. the above really needs to be reworded to pass legal muster.
We will credit you for your
changes as far as possible, to give credit but also to keep a trace
back to who made what changes.  Please always provide us with your
full real name when contributing!

See `Contribution Guidelines
<https://nghttp2.org/documentation/contribute.html>`_ for more
details.

Versioning
----------

In general, we follow `Semantic Versioning <http://semver.org/>`_.

We may release PATCH releases between the regular releases, mainly for
severe security bug fixes.

We have no plan to break API compatibility changes involving soname
bump, so MAJOR version will stay 1 for the foreseeable future.

License
-------

The MIT License