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    1 v1.15.17
    2 --------------------------------------------------------------------------------
    3  * Integrated changes from Apache trunk.
    4  * Log requests and sent the configured error response in case of early detected
    5    errors like too many or too long headers. [Ruediger Pluem]
    6  * added test for buffering across a mod_http2+mod_proxy_http2 connection
    7  * added TRACE2 logging to show buffering flag when writing task output
    8  * new option 'H2OutputBuffering on/off' which controls the buffering of stream output.
    9    The default is on, which is the behaviour of older mod-h2 versions. When off, all
   10    bytes are made available immediately to the main connection for sending them
   11    out to the client. This fixes interop issues with certain flavours of gRPC, see
   12    als #207.
   13  * Eliminated some Python deprecation warnings in test code.
   14  
   15 v1.15.16
   16 --------------------------------------------------------------------------------
   17  * Fixed reporting of transferred bytes for mod_logio for modifiers %O (and %S) to
   18    report the number of transferred header and body lengths. This is still only
   19    an approximation of the bytes on the connection. The data is subject to header
   20    compression and h2 framing afterwards. Grain of salt. Fixes #203.
   21  
   22 v1.15.14
   23 --------------------------------------------------------------------------------
   24  * Removing support for abandoned draft of http-wg regarding cache-digests.
   25 
   26 v1.15.13
   27 --------------------------------------------------------------------------------
   28  * Fixes #200: "LimitRequestFields 0" now disables the limit, as documented.
   29 
   30 v1.15.12
   31 --------------------------------------------------------------------------------
   32  * Fixes #201: do not count repeated headers with same name against the field
   33    count limit. The are merged internally, as if sent in a single HTTP/1 line.
   34  * Refrain from detecting (intermediate) responses, when the connection has
   35    already been aborted or non-flush meta buckets are encountered.
   36  * Changed terminology to master/secondary connections in the source.
   37  * Test against the installed version of the module. This allows test cases
   38    to work with other versions.
   39 
   40 v1.15.11
   41 --------------------------------------------------------------------------------
   42  * mod_proxy_http2: the "ping" proxy parameter 
   43    (see <https://httpd.apache.org/docs/2.4/mod/mod_proxy.html>) is now used
   44    when checking the liveliness of a new or reused h2 connection to the backend.
   45    With short durations, this makes load-balancing more responsive. The module
   46    will hold back requests until ping conditions are met, using features of the
   47    HTTP/2 protocol alone. [Ruediger Pluem, Stefan Eissing]
   48 
   49 v1.15.10
   50 --------------------------------------------------------------------------------
   51  * mod_proxy_http2: respect ProxyTimeout settings on backend connections
   52    while waiting on incoming data. [Ruediger Pluem, Stefan Eissing]
   53 
   54 v1.15.9
   55 --------------------------------------------------------------------------------
   56  * Since v1.15.4 mod_reqtimeout was enabled for h2 connections. This lead to closing of
   57    h2 connections when a handshake timeout was configured, irregardless if the handshake
   58    did happen or not. Added a positive test next to the negative one to ensure that 
   59    mod_reqtimeout is removed after a successful handshake. Fixes #196 
   60 
   61 v1.15.8
   62 --------------------------------------------------------------------------------
   63  * Fixed an unfortunate regression introduced in v1.15.7 that prevented
   64    H2_STREAM_ID to be set. Fixes <https://bz.apache.org/bugzilla/show_bug.cgi?id=64330>
   65    and Windows crashes reported in <https://www.apachelounge.com/viewtopic.php?p=39012#39012>. 
   66  * Synch with code spell/APLOGNO changes from Apache svn.
   67 
   68 v1.15.7
   69 --------------------------------------------------------------------------------
   70  * Fixes issue #195 regarding h2 slave connection ids that resulted in duplicate
   71    request ids being generated under loads.
   72 
   73 v1.15.6
   74 --------------------------------------------------------------------------------
   75  * Fix by Joe Orton for a gcc 10 warnings on s390x.
   76 
   77 v1.15.5
   78 --------------------------------------------------------------------------------
   79  * Fixed rare cases where a h2 worker could deadlock the main connection. All the good
   80    bits in this thanks to Yann Ylavic.
   81  
   82 v1.15.4
   83 --------------------------------------------------------------------------------
   84  * Fixed interaction with mod_reqtimeout. mod-h2 was knocking it out completely, however
   85    it allow configuration of the TLS handshake timeout and that is very useful indeed.
   86    Also, fixed a stupid mistake of mine that made `H2Direct` always `on`, irregardless 
   87    of configuration. Found and reported by <Armin.Abfalterer@united-security-providers.ch> and
   88    <Marcial.Rion@united-security-providers.ch>. Thanks!
   89  * Switched test suite and test cgis to python3. A regression in cgi.Fieldstorage() makes
   90    tests skip chunked uploads at the moment. Sad.
   91  * Merged PR by @mkaufmann that avoids multiple field lengths violations to be logged
   92    on the same request.
   93  
   94 v1.15.3
   95 --------------------------------------------------------------------------------
   96  * fixes Timeout vs. KeepAliveTimeout behaviour, see PR 63534 (for trunk now,
   97    mpm event backport to 2.4.x up for vote). 
   98  * Fixes stream cleanup when connection throttling is in place. 
   99  * Counts stream resets by client on streams initiated by client as cause 
  100    for connection throttling.
  101  * Header length checks are now logged similar to HTTP/1.1 protocol handler (thanks @mkaufmann)
  102  * Header length is checked also on the merged value from several header instances
  103    and results in a 431 response.
  104  
  105 v1.15.2
  106 --------------------------------------------------------------------------------
  107  * fixing mod_proxy_http2 to support trailers in both directions. See PR 63502.
  108 
  109 v1.15.1
  110 --------------------------------------------------------------------------------
  111  * further copying of passed data to disentangle worker and main connection.
  112 
  113 v1.15.0
  114 --------------------------------------------------------------------------------
  115  - reverted as no good.
  116 
  117 v1.14.3
  118 --------------------------------------------------------------------------------
  119  * Integrated latest changes from trunk. In particular mod_proxy_http2 connection
  120    reuse and retry changes by @rpluem.
  121  
  122 v1.14.2
  123 --------------------------------------------------------------------------------
  124  * Integrated a forgotten request init fix from Apache subversion
  125  * When a TLS renegotiation is denied, configured error documents could prevent
  126    the proper HTTP/2 stream reset to happen. Fix by Michael Kaufmann (@mkauf).
  127  * Added a test case for #172
  128 
  129 v1.14.1
  130 --------------------------------------------------------------------------------
  131  * Tweaks to new H2Padding, now simply is of the form:
  132     ```H2Padding numbits```
  133    and applies a *random* number of padding bytes to each payload frame. The
  134    range is from [0, 2^N[. The default is 0, so no padding.
  135  
  136 v1.14.0
  137 --------------------------------------------------------------------------------
  138  * new configuration directive:
  139     ```H2Padding [ 'prefer' | 'enforce' ] numbits```
  140     to control padding of HTTP/2 payload frames. 'numbits' is a number from 0-8,
  141     where 0 disables padding and 1-8 is the power of 2 that frame lengths are
  142     rounded to. The default is 4 bits, e.g. frames are padded to be a multiple
  143     of 16 (2^4).
  144     While 'enforce' always applies this to all payload frames, the default 'prefer'
  145     option caps frame length at H2TLSWarmUpSize when in effect.
  146   
  147 v1.13.1
  148 --------------------------------------------------------------------------------
  149  * mod_http2: cleanup of the now dead h2_req_engine support, no functional change.
  150 
  151 v1.13.0
  152 --------------------------------------------------------------------------------
  153  * mod_proxy_http2: simplifying implementation and reducing memory use by only
  154    running a single request at the time on a h2 backend connection. The previous
  155    implementation was just not good enough regarding flow control on the overall
  156    server and too complex compared to the performance benefits achieved. The goal
  157    with this change is to establish a solid base from which to optimize things
  158    again.
  159  * Fixes slave connection input filter to use proper return code on speculative read
  160    encountering an EOF.
  161  * Starting test_600 for mod_proxy_http2 use on server itself
  162 
  163 v1.12.5
  164 --------------------------------------------------------------------------------
  165  * Analyzing PR63170 more, mod_proxy_http2 needs to differentiate between its hosting
  166    stream gone and its master connection gone. The later is terminal, the former is not.
  167  * mod_proxy_http2: ping the other side of an idle connection only when not already
  168    waiting on a PING response.
  169 
  170 v1.12.4
  171 --------------------------------------------------------------------------------
  172  * Fixed an issue where a proxy_http2 handler entered an infinit loop when encountering
  173    certain errors on the backend connection. 
  174    See <https://bz.apache.org/bugzilla/show_bug.cgi?id=63170>.
  175 
  176 v1.12.3
  177 --------------------------------------------------------------------------------
  178  * fixed bug in nghttp output parsing that filters now Frames sent/received inbetween
  179    response body DATA. 
  180  * added test cases for nghttp output parsing which is screen scraping, so controlled
  181    failure make debugging issues easier
  182  * fixed an issue with curl detecting when configure --with-curl=path was used.
  183  * added multi-resource retrieval tests via nghttp -a
  184  * added Test for the h2 status handler
  185  * More POST and form upload tests with nghttp client
  186  * added POST tests in a http: proxied setup
  187 
  188 v1.12.2
  189 --------------------------------------------------------------------------------
  190  * Fixed keepalives counter on slave connections.
  191 
  192 v1.12.1
  193 --------------------------------------------------------------------------------
  194  * Fixed Bug introduce in v1.12.0 where mod_proxy_http2 no longer set the server name
  195    on new backend connections.
  196  * Fixed issue where mod_proxy_http2 would trigger an invalid internal state when retrying requests.
  197  * applied patch for #167 provided by Michael Kaufmann (@mkauf) about errors on
  198    HEAD requests (h2 streams not closed cleanly), for example those served by mod_cgid.
  199 
  200 v1.12.0
  201 --------------------------------------------------------------------------------
  202  * H2Upgrade can be configured per directory/location. Test case added.
  203  * H2Push can be disabled per directory/location. Test case added.
  204  * Configuration rework to open up several directives for use in locations and directories
  205    and .htaccess files.
  206  * Merging changes from httpd/trunk + httpd/branches/2.4.x to have a unified source again.
  207 
  208 v1.11.4
  209 --------------------------------------------------------------------------------
  210  * Changed cleanup strategy for slave connections.
  211  * Added test case for <https://bz.apache.org/bugzilla/show_bug.cgi?id=62654>
  212  * Adding an mpm check so that mod_http2 also compiles against Apache httpd trunk.
  213 
  214 v1.11.3
  215 --------------------------------------------------------------------------------
  216  * Adding defensive code for stream EOS handling, in case the request handler somehow
  217    missed to signal it the normal way. Should address #167 and #170. 
  218  
  219 v1.11.2
  220 --------------------------------------------------------------------------------
  221  * Fixed configure to no longer require ```libcurl-devel```, but only the ```curl```
  222    command with h2 support for testing.
  223 
  224 v1.11.1
  225 --------------------------------------------------------------------------------
  226  * added test/Makefile.in to the release tar ball, so that peopl just need
  227    automake to build (reported in #169 by @uhliarik, fix proposed by @notroj)
  228  * added  -avoid-version to the linker flags (thanks to Oden Erikson, @odeneriksson)
  229  * added tests for 100 interim responses
  230  * added tests for trailers
  231  * added tests for conditional request header
  232  * added tests for invalid characters in response header
  233  * added Upgrade: response header tests
  234  * added vars require configuration tests
  235  * added ssl renegotiation tests
  236 
  237 v1.11.0
  238 --------------------------------------------------------------------------------
  239  * connection IO event handling reworked. Instead of reacting on incoming bytes, the
  240    state machine now acts on incoming frames that are affecting it. This reduces
  241    state transitions.
  242  * pytest suite now covers some basic tests on h2 selection, GET and POST
  243  * started to add pytest suite from existing bash tests
  244 
  245 v1.10.21
  246 --------------------------------------------------------------------------------
  247  * Code cleanups from Apache subversion
  248  * New optional function to query the number of h2 workers from Apache branch
  249 
  250 v1.10.20
  251 --------------------------------------------------------------------------------
  252  * Restore keepalive handling of v1.10.16. Idle connections are kept open
  253    for the duration.
  254 
  255 v1.10.19
  256 --------------------------------------------------------------------------------
  257  * adding regular memory cleanup when transferring large response bodies. This
  258    reduces memory footprint and avoids memory exhaustion when transferring large files
  259    on 32-bit architectures.
  260 
  261 v1.10.18
  262 --------------------------------------------------------------------------------
  263  * fixes a race condition where aborting streams triggers an unnecessary timeout.
  264 
  265 v1.10.17
  266 --------------------------------------------------------------------------------
  267  * accurate reporting of h2 data input/output per request via mod_logio. Fixes
  268    an issue where output sizes where counted n-times on reused slave connections. See #158.
  269  * normalized connection prefix logging when trace2 is enabled for direct h2 connection
  270    detection.
  271 
  272 v1.10.16
  273 --------------------------------------------------------------------------------
  274  * Removed no longer used code in stream cleanup, disabled beam events
  275    during pool shutdown, discouraged content-encoding filter from applying
  276    themselves to http2_status responses.
  277 
  278 v1.10.15
  279 --------------------------------------------------------------------------------
  280  * discourage gzip/brotli content encoding on http2-status responses as
  281    they are inserted into the reponse when filters are already done.
  282 
  283 v1.10.14
  284 --------------------------------------------------------------------------------
  285   * fixed unfair scheduling when number of active connections
  286      exceeded the scheduling fifo capacity.
  287 
  288 v1.10.13
  289 --------------------------------------------------------------------------------
  290   * avoid unnecessary data retrieval for a trace log. Allow certain
  291     information retrievals on null bucket beams where it makes sense.
  292   * Fixed configure to check first for libs and then add compiler flags
  293 
  294 v1.10.12
  295 --------------------------------------------------------------------------------
  296   * Reverting 1.10.11 change since showed no effect on issue #120
  297   * Fixes a race condition on request body handling.
  298 
  299 v1.10.11
  300 --------------------------------------------------------------------------------
  301   * DoS flow control protection is less agressive as long as active tasks stay
  302     below worker capacity. Intended to fix problems with media streaming.
  303 
  304 v1.10.10
  305 --------------------------------------------------------------------------------
  306   * adding signalling of data available before waiting on beam buffer to drain. Missing this causes suspended streams to stall and time out.
  307 
  308 v1.10.9
  309 --------------------------------------------------------------------------------
  310   * cleanup of bucket beam change signaling to track down issue #143
  311 
  312 v1.10.8
  313 --------------------------------------------------------------------------------
  314   * a stream could stall and not send any more output to the client which in the end aborts the connection due to a timeout.
  315 
  316 v1.10.7
  317 --------------------------------------------------------------------------------
  318   * disable and give warning when mpm_prefork is encountered. The server will
  319     continue to work, but HTTP/2 will no longer be negotiated.
  320   * improved implementation of ready queue.
  321 
  322 v1.10.6
  323 --------------------------------------------------------------------------------
  324   * Fix for possible CPU busy loop introduced in v1.10.3 where a stream may keep
  325     the session in continuous check for state changes that never happen.
  326 
  327 v1.10.5
  328 --------------------------------------------------------------------------------
  329   * fail requests without ERROR log in case we need to read interim
  330     responses and see only garbage. This can happen if proxied servers send
  331     data where none should be, e.g. a body for a HEAD request.
  332 
  333 v1.10.4
  334 --------------------------------------------------------------------------------
  335   * mod_proxy_http2: adding support for Reverse Proxy Request headers.
  336 
  337 v1.10.3
  338 --------------------------------------------------------------------------------
  339   * fixed possible deadlock that could occur when connections were 
  340      terminated early with ongoing streams. Fixed possible hanger with timeout
  341      on race when connection considers itself idle. 
  342 
  343 v1.10.2
  344 --------------------------------------------------------------------------------
  345   * MaxKeepAliveRequests now limits the number of times a 
  346     slave connection gets reused.
  347   * Client streams that lack the EOF flag get now forcefully
  348     closed with a RST_STREAM (NO_ERROR) when the request has been answered.
  349   * Only when 'HttpProtocolOptions Unsafe' is configured, will
  350     control characters in response headers or trailers be forwarded to the
  351     client. Otherwise, in the default configuration, a request will eiher 
  352     fail with status 500 or the stream will be reset by a RST_STREAM frame. 
  353      
  354 v1.10.1
  355 --------------------------------------------------------------------------------
  356   * Fixed bug in re-attempting proxy requests after connection error. 
  357     Reliability of reconnect handling improved.
  358   * Fixed two rare deadlocks with new non-nested mutex use.
  359   * No longer mapping Link: header urls in proxy requests when preserve host
  360     is set.
  361 
  362 v1.10.0
  363 --------------------------------------------------------------------------------
  364   * better performance, eliminated need for nested locks and
  365     thread privates. Moving request setups from the main connection to the
  366     worker threads. Increase number of spare connections kept.
  367   * input buffering and dynamic flow windows for increased 
  368     throughput. Requires nghttp2 >= v1.5.0 features. Announced at startup
  369     in mod_http2 INFO log as feature 'DWINS'.
  370   * h2 workers with improved scalability for better scheduling
  371     performance. There are H2MaxWorkers threads created at start and the
  372     number is kept constant for now.
  373   * obsoleted option H2SessionExtraFiles, will be ignored and
  374     just log a warning.
  375   * fixed PR60869 by making h2 workers exit explicitly waking up
  376     all threads to exit in a defined way.
  377      
  378 v1.9.3
  379 --------------------------------------------------------------------------------
  380   * moving session cleanup to pre_close hook to avoid races with
  381     modules already shut down and slave connections still operating.
  382   * stream timeouts now change to vhost values once the request
  383     is parsed and processing starts. Initial values are taken from base
  384     server or SNI host as before. [Stefan Eissing]
  385   * fixed retry behaviour for http2 proxy connections when frontend 
  386     connection uses http/1.1.     
  387   * separate mutex instances for each bucket beam, resulting in 
  388     less lock contention. input beams only created when necessary.
  389 
  390 v1.9.2
  391 --------------------------------------------------------------------------------
  392   * mod_http2: adding allocator mutex to session pool due to reports of rare
  393     crashes.
  394     
  395 v1.9.1
  396 --------------------------------------------------------------------------------
  397   * mod_proxy_http2: support for ProxyPreserveHost directive
  398 
  399 v1.9.0
  400 --------------------------------------------------------------------------------
  401   * not counting file buckets again stream max buffer limits. 
  402     Effectively transfering static files in one step from slave to master 
  403     connection.    
  404   * mod_http2: comforting ap_check_pipeline() on slave connections
  405     to facilitate reuse (see https://github.com/icing/mod_h2/issues/128).
  406     [reported by Armin Abfalterer]
  407   * mod_http2: http/2 streams now with state handling/transitions as defined
  408     in RFC7540. Stream cleanup/connection shutdown reworked to become easier
  409     to understand/maintain/debug. Added many asserts on state and cleanup 
  410     transitions.
  411  
  412 v1.8.11
  413 --------------------------------------------------------------------------------
  414   * regression fix on bugzilla PR 59348, on graceful restart, ongoing 
  415     streams are finished normally before the final GOAWAY is sent.
  416   * do not attempt to generated a response on an already aborted slave connection
  417   * fix potential double cleanup of bucket beam memory
  418 
  419 v1.8.10
  420 --------------------------------------------------------------------------------
  421   * fixes bugzilla PR60599, sending proper response for conditional requests
  422     answered by mod_cache. (orignal patch by Jeff Wheelhouse)
  423 
  424 v1.8.9
  425 --------------------------------------------------------------------------------
  426   * rework of stream resource cleanup to avoid a crash in a close
  427     of a lingering connection. Prohibit special file bucket beaming for
  428     shared buckets. Files sent in stream output now use the stream pool
  429     as read buffer, reducing memory footprint of connections.
  430     (much help from Yann Ylavic)
  431 
  432 v1.8.8
  433 --------------------------------------------------------------------------------
  434   * streaming of request output now reacts timely to data
  435     from other streams becoming available. Same for new incoming requests.
  436  
  437 v1.8.7
  438 --------------------------------------------------------------------------------
  439   * fix for possible page fault when stream is resumed during session shutdown. 
  440     (Patch by sidney-j-r-m, github)
  441   * fix for h2 session ignoring new responses while already
  442     open streams continue to have data available.
  443      
  444 v1.8.6
  445 --------------------------------------------------------------------------------
  446   * adding support for MergeTrailers directive. 
  447   * limiting DATA frame sizes by TLS record sizes in use on the     
  448     connection. Flushing outgoing frames earlier.
  449 
  450 v1.8.5
  451 --------------------------------------------------------------------------------
  452   * Removed debug log statements left over in 1.8.4 release.
  453   
  454 v1.8.4
  455 --------------------------------------------------------------------------------
  456   * Cleanup beamer registry on server reload, Fixes Apache bugzilla PR60510.
  457     Patch by Pavel Mateja <pavel@verotel.cz>
  458   * Fixes #126 e.g. beam bucket lifetime handling when data is sent 
  459     over temporary pools.
  460 
  461 v1.8.3
  462 --------------------------------------------------------------------------------
  463   * CVE-2016-8740: Mitigate DoS memory exhaustion via endless
  464     CONTINUATION frames. Reported by Naveen Tiwari <naveen.tiwari@asu.edu> and 
  465     CDF/SEFCOM at Arizona State University
  466   * Removing some warning when streams are cleaned up that were never scheduled
  467 
  468 
  469 v1.8.2
  470 --------------------------------------------------------------------------------
  471   * new directive 'H2EarlyHints' to enable sending of HTTP status 103 interim
  472     responses. Off by default since some browser still choke on them.
  473   * mod_proxy_http2 will, when used on top of a HTTP/1.x connection, only 
  474     forward 100 responses from the backend if the client expects them. All
  475     other responses in the 100 range are filtered.
  476 
  477 v1.8.0
  478 --------------------------------------------------------------------------------
  479   * mod_http2: new directive 'H2PushResource' to enable early pushes before 
  480     processing of the main request starts. Resources are announced to the 
  481     client in Link headers on a 103 early hint response. 
  482     All responses with status code <400 are inspected for Link header and
  483     trigger pushes accordingly. 304 still does prevent pushes.
  484     'H2PushResource' can mark resources as 'critical' which gives them higher
  485     priority than the main resource. This leads to preferred scheduling for
  486     processing and, when content is available, will send it first. 'critical'
  487     is also recognized on Link headers.
  488   * mod_proxy_http2: uris in Link headers are now mapped back to a suitable
  489     local url when available. Relative uris with an absolute path are mapped
  490     as well. This makes reverse proxy mapping available for resources
  491     announced in this header. 
  492     With 103 interim responses being forwarded to the main client connection,
  493     this effectively allows early pushing of resources by a reverse proxied
  494     backend server.
  495   * mod_proxy_http2: adding support for 103 status code, as proposed by
  496     Kazuho Oku.
  497 
  498 v1.7.9
  499 --------------------------------------------------------------------------------
  500   * fixed a crash in stream shutdown introduced in 1.7.8
  501 
  502 v1.7.8
  503 --------------------------------------------------------------------------------
  504   * unannounced and multiple interim responses (status code < 200)
  505     are parsed and forwarded to client until a final response arrives.
  506   * mod_proxy_http2: improved robustness when main connection is closed early
  507     by resetting all ongoing streams against the backend.
  508   * mod_http2: allocators from slave connections are released earlier, resulting
  509     in less overall memory use on busy, long lived connections.
  510 
  511 v1.7.6
  512 --------------------------------------------------------------------------------
  513   * fixed crash in beam memory handling introduced in 1.7.x changes
  514 
  515 v1.7.5
  516 --------------------------------------------------------------------------------
  517   * properly implemented 100-continue handling for proxy setups, be it
  518     mod_proxy_http or mod_proxy_http2
  519   * reusing backend HTTP/2 connections more than a second old will hold back
  520     request bodies until a PING response is received. Headers are still sent
  521     right away since those are repeatable on a new connection.
  522   
  523   
  524 v1.7.3
  525 --------------------------------------------------------------------------------
  526   * reverts some int -> apr_uint32_t changes made in 1.7.0 to address possible
  527     crashes.
  528     
  529 v1.7.2
  530 --------------------------------------------------------------------------------
  531   * fixes compilation error on 32 bit systems when generating slave connection id.
  532 
  533 v1.7.1
  534 --------------------------------------------------------------------------------
  535   * fix for build issues on Windows platforms
  536 
  537 v1.7.0
  538 --------------------------------------------------------------------------------
  539   * rewrite of how responses and trailers are transferred between master and 
  540     slave connections.
  541   * Reduction of internal states for tasks and streams, reducing complexity
  542     for increased stability. 
  543   * Heuristic id generation for slave connections to better keep promise of 
  544     connection ids unique at given point in time. This fixes problems with
  545     mod_cgid in high load situtations. 
  546   * Fix for handling of incoming trailers when no request body is sent.
  547 
  548 v1.6.2
  549 --------------------------------------------------------------------------------
  550   * fixes a race that led to output blocking (stream not finishing)
  551 
  552 v1.6.1
  553 --------------------------------------------------------------------------------
  554   * if configured with nghttp2 1.14.0 and onward, invalid request
  555     headers will immediately reset the stream with a PROTOCOL error. Feature
  556     logged by module on startup as 'INVHD' in info message.
  557   * fixed handling of stream buffers during shutdown.
  558      
  559 v1.6.0
  560 --------------------------------------------------------------------------------
  561  * handling graceful shutdown gracefully, e.g. processing existing streams to the end.
  562  * h2 status resource follows latest draft, see
  563    http://www.ietf.org/id/draft-benfield-http2-debug-state-01.txt
  564    Configure it as
  565    <Location "/.well-known/h2/state">
  566         SetHandler http2-status
  567     </Location>
  568  * support for 'Expect: 100-continue' handling
  569 
  570 v1.5.13
  571 --------------------------------------------------------------------------------
  572  * new H2CopyFiles directive that changes treatment of file handles in 
  573    responses. Necessary in order to fix broken lifetime handling in modules 
  574    such as mod_wsgi. Use 'H2CopyFiles off' where ever you need it.
  575  * removing timeouts on master connection while requests are being processed. 
  576    Requests may timeout, but the master only times out when no more requests 
  577    are active.
  578 
  579 v1.5.12
  580 --------------------------------------------------------------------------------
  581  * fixed connection flushing when handling SETTINGS and no stream is open.
  582    (thanks @summerwind)
  583  * fix for request abort when connections drops, introduced in 1.5.8
  584  * more rigid error handling in DATA frame assembly, leading
  585    to deterministic connection errors if assembly fails.
  586 
  587 v1.5.10
  588 --------------------------------------------------------------------------------
  589  * fixed bug in error handling when passing DATA frames.
  590 
  591 v1.5.9
  592 --------------------------------------------------------------------------------
  593  * more strict error handling and logging in DATA frame assembly.
  594 
  595 v1.5.8
  596 --------------------------------------------------------------------------------
  597  * mod_http2: improved cleanup of connection/streams/tasks to always
  598    have deterministic order regardless of event initiating it. Addresses
  599    reported crashes due to memory read after free issues. 
  600   
  601 v1.5.7
  602 --------------------------------------------------------------------------------
  603  * fixed read after free on certain conditions when clients abort connections
  604  * fixed connection shutdown when stream tasks block on reads
  605 
  606 v1.5.6
  607 --------------------------------------------------------------------------------
  608  * fixed possible null pointer reference in new bucket beams during read on an 
  609    aborted beam
  610  * improved event handling on master connection (idle/submit/wait) to increase 
  611    performance
  612  
  613 v1.5.5
  614 -------------------------------------------------------------------------------- 
  615  * Fix async write issue that sometimes led to selection of wrong timeout
  616    vs. keepalive timeout selection for idle sessions.
  617  * Checking LimitRequestLine, LimitRequestFields and 
  618    LimitRequestFieldSize configurated values for incoming streams. Returning
  619    HTTP status 431 for too long/many headers fields and 414 for a too long
  620    pseudo header.
  621  * Tracking conn_rec->current_thread on slave connections, so
  622    that mod_lua finds the correct one. Fixes PR 59542.
  623 
  624 v1.5.3
  625 -------------------------------------------------------------------------------- 
  626  * slave connections have conn_rec->aborted flag set when a stream
  627    has been reset by the client.
  628  * Small fixes in bucket beams when forwarding file buckets. Output handling
  629    on master connection uses less FLUSH and passes automatically when more
  630    than half of H2StreamMaxMemSize bytes have accumulated.
  631    Workaround for http: when forwarding partial file buckets to keep the
  632    output filter from closing these too early.
  633  * elimination of fixed master connectin buffer for TLS connections. New 
  634    scratch bucket handling optimized for TLS write sizes. 
  635    File bucket data read directly into scratch buffers, avoiding one
  636    copy. Non-TLS connections continue to pass buckets unchanged to the core
  637    filters to allow sendfile() usage.
  638  * h2_request.c is no longer shared between these modules. This simplifies 
  639    building on platforms such as Windows, as module reference used in 
  640    logging is now clear.
  641      
  642 v1.5.2
  643 -------------------------------------------------------------------------------- 
  644  * fixed connection shutdown deadlock on linux when client closed early
  645  * beam shutdown does now wait on endpoint to finish using buckets in flight,
  646    hopefully addressing crash issues completely 
  647  * Since 1.5.1 the internal HTTP/2 protocol is reported as "HTTP/2.0" for
  648    better compatibility and since CGI's SERVER_PROTOCOL seems to require this
  649    format
  650     
  651 v1.5.1
  652 -------------------------------------------------------------------------------- 
  653  * fixed segmentation fault when connections where aborted by client in new
  654    bucket beam code
  655  * eliminated one more memory pool per stream
  656  
  657 v1.5.0
  658 -------------------------------------------------------------------------------- 
  659  * mod_proxy_http2 for backend HTTP/2 connections, currently cleartext only
  660  * new "bucket beam" technology to transport buckets across threads without 
  661    buffer copy. 
  662  * delaying response start until flush or enough body data has been accumulated.
  663  * all fixed up to and including 1.4.7
  664      
  665 v1.4.7
  666 -------------------------------------------------------------------------------- 
  667  * disabling file mmap handling as this leads to segmentation faults when files
  668    are truncates while being streamed out. 
  669  * Some additional trace1 logging when connections give unexpected errors, e.g.
  670    clients close connection without final GOAWAY frame. 
  671  
  672 v1.4.6 (as released in Apache httpd 2.4.20)
  673 -------------------------------------------------------------------------------- 
  674  * incrementing keepalives on each request started so that logging %k gives 
  675    increasing numbers per master http2 connection. New documented variables 
  676    in env, usable in custom log formats: H2_PUSH, H2_PUSHED, H2_PUSHED_ON, 
  677    H2_STREAM_ID and H2_STREAM_TAG.
  678  * more efficient passing of response bodies with less contention
  679      and file bucket forwarding.
  680  * fix for missing score board updates on request count, fix for memory leak 
  681    on slave connection reuse.
  682  * disabling PUSH when client sends GOAWAY. Slave connections are reused for 
  683    several requests, improved performance and better memory use. 
  684  * fixes problem with wrong lifetime of file buckets on main connection.
  685  * fixes incorrect denial of requests without :authority header.
  686  * give control to async mpm for keepalive timeouts only when no streams are 
  687    open and even if only after 1 sec delay. Under load, event mpm discards 
  688    connections otherwise too quickly.
  689  * fixed possible read after free when streams were cancelled early by the 
  690    client.
  691  * fixed possible deadlock during connection shutdown. Thanks to @FrankStolle 
  692    for reporting and getting the necessary data.
  693  * fixed apr_uint64_t formatting in a log statement to user proper APR def, 
  694    thanks to @Sp1l.
  695  * number of worker threads allowed to a connection is adjusting 
  696    dynamically. Starting with 4, the number is doubled when streams can be 
  697    served without block on http/2 connection flow. The number is halfed, when
  698    the server has to wait on client flow control grants. 
  699    This can happen with a maximum frequency of 5 times per second. 
  700    When a connection occupies too many workers, repeatable requests 
  701    (GET/HEAD/OPTIONS) are cancelled and placed back in the queue. Should that 
  702    not suffice and a stream is busy longer than the server timeout, the 
  703    connection will be aborted with error code ENHANCE_YOUR_CALM.
  704    This does *not* limit the number of streams a client may open, rather the
  705    number of server threads a connection might use.
  706  * allowing link header to specify multiple "rel" values, space-separated 
  707    inside a quoted string. Prohibiting push when Link parameter "nopush" is 
  708    present.
  709  * reworked connection state handling. Idle connections accept a GOAWAY from 
  710    the client without further reply. Otherwise the module makes a best effort 
  711    to send one last GOAWAY to the client.
  712  * the values from standard directives Timeout and KeepAliveTimeout properly 
  713    are applied to http/2 connections.
  714  * idle connections are returned to async mpms. new hook "pre_close_connection" 
  715    used to send GOAWAY frame when not already done. Setting event mpm server 
  716    config "by hand" for the main connection to the correct negotiated server.
  717  * keep-alive blocking reads are done with 1 second timeouts to check for MPM 
  718    stopping. Will announce early GOAWAY and finish processing open streams, 
  719    then close.
  720  * bytes read/written on slave connections are reported via the optional 
  721    mod_logio functions. Fixes PR 58871.
  722  * connections how keep a "push diary" where hashes of already pushed resources 
  723    are kept. See directive H2PushDiarySize for managing this. Push diaries can 
  724    be initialized by clients via the "Cache-Digest" request header. 
  725    This carries a base64url encoded. compressed Golomb set as described
  726    in https://datatracker.ietf.org/doc/draft-kazuho-h2-cache-digest/
  727    Introduced a status handler for HTTP/2 connections, giving various counters
  728    and statistics about the current connection, plus its cache digest value
  729    in a JSON record. Not a replacement for more HTTP/2 in the server status. 
  730    Configured as
  731    <Location "/http2-status">
  732        SetHandler http2-status
  733    </Location>
  734  * Fixed flushing of last GOAWAY frame. Previously, that frame did not always 
  735    reach the client, causing some to fail the next request.
  736    Fixed calculation of last stream id accepted as described in rfc7540. 
  737    Reading in KEEPALIVE state now correctly shown in scoreboard. 
  738    Fixed possible race in connection shutdown after review by Ylavic. 
  739    Fixed segfault on connection shutdown, callback ran into a semi dismantled session. 
  740  * Added support for experimental accept-push-policy draft
  741    (https://tools.ietf.org/html/draft-ruellan-http-accept-push-policy-00). Clients
  742    may now influence server pushes by sending accept-push-policy headers.
  743  * new r->subprocess_env variables HTTP2 and H2PUSH, set to "on"
  744    when available for request.
  745  * mod_status/scoreboard: showing connection protocol in new column, new 
  746    ap_update_child_status methods for updating server/description. mod_ssl
  747    sets vhost negotiated by servername directly.
  748 
  749 v1.2.8
  750 -------------------------------------------------------------------------------- 
  751  * Requests without ':authority' header, using 'Host' instead, are no longer
  752    denied.
  753    
  754 v1.2.7
  755 -------------------------------------------------------------------------------- 
  756  * Adding logio fix from apache trunk so that resource sizes are correcly 
  757    reported in access logs.
  758 
  759 v1.2.6
  760 -------------------------------------------------------------------------------- 
  761  * Adding 'accept-encoding' to headers used in PUSHed resources - as sent by
  762    the initiating request.
  763 
  764 v1.2.5
  765 -------------------------------------------------------------------------------- 
  766  * fixes a deadlock that caused connections to get stuck in output, locking
  767    up the connection and a server thread forever. Thanks to @FrankStolle for
  768    reporting and getting the necessary data.
  769  
  770 v1.2.4
  771 -------------------------------------------------------------------------------- 
  772  * removed all H2*Timeout directives. HTTP/2 uses not the same Timeout and
  773    KeepAliveTimeout as HTTP/1.1.
  774  * enforcing the Timeout value on read and write operations from the selected
  775    virtual host (TLS+SNI). httpd was wrongly using the defaults set in the
  776    base server config.
  777  * add DEBUG logging to see if writing properly returns to catch a connection
  778    hanger reported in #79
  779  
  780 v1.2.3
  781 -------------------------------------------------------------------------------- 
  782  * connection timeout handling when requests do not report back
  783  * setting correct server config for event mpm on main connection, so that
  784    timeouts, keepalives use the correct values
  785  * fixes event hack to match changes in structures
  786 
  787 v1.2.2
  788 -------------------------------------------------------------------------------- 
  789  * removed unused code
  790  
  791 v1.2.1
  792 -------------------------------------------------------------------------------- 
  793  * fixed compilation error because of stupid own log2n function
  794  * fixed cache digest calculation to spit out same values as Kazuho Oku's
  795    reference implementation (https://github.com/kazuho/h2-cache-digest).
  796  
  797 v1.2.0
  798 -------------------------------------------------------------------------------- 
  799  * Each connection now has a push diary where already pushed resources are
  800    recorded (as 64-bit subsets sha256 URL hashes). The maximum size of a diary
  801    can be configured with the new directive 'H2PushDiarySize'. The default is 256.
  802  * The module recognizes the request header 'Cache-Digest', carrying a base64url
  803    encoded set of hash values using Golomb set encoding as described in
  804       https://datatracker.ietf.org/doc/draft-kazuho-h2-cache-digest/
  805    This is highly experimental and will most likely change in format and
  806    interpretation as the draft evolves. For now, this value is used to replace
  807    the current push diary. This allows clients to inform the server about
  808    which resources they already have cached.
  809  * module configuration now looks to the crypto library (because it wants SHA256
  810    from it). If it is not found, a replacement hash is used, however this is
  811    not interoperable with cache digests from clients, e.g. hits will be missed.
  812  * the module has a new handler named "http2-status" which exposes certain
  813    properties and statistics of the *current* HTTP/2 connection. It can be 
  814    configured just like:
  815        <Location "/http2-status">
  816          SetHandler http2-status
  817        </Location>
  818    The usual precautions about exposing some internals of your server to the
  819    outside world apply. Just as for "server-status"."
  820  * Due to more test cases and new functions, more bugs have been exposed,
  821    examined and exterminated.
  822 
  823 v1.1.0
  824 -------------------------------------------------------------------------------- 
  825  * GOAWAY will be sent when a HTTP/2 connection is shutdown, whenever the
  826    connection still allows it. Calculation of the last stream id has been
  827    corrected to include streams started, not only streams finished processing.
  828  * several issues fixed with new fuzzing tests that simulate random closes 
  829    and delays/timeouts
  830  * H2SessionExtraFiles are now shared between all sessions in the same process.
  831    It now works like this:
  832    H2MaxWorkers * H2SessionFiles is assumed to be the total number of file
  833    handles that can be safely used for HTTP/2 transfers without other parts
  834    of the server running out of handles. This number is shared between all
  835    HTTP/2 connections in the same server process.
  836    The default is set to 2. With H2MaxWorkers on most platforms/mpms
  837    defaulting to 25 that gives a maximum of 50 handles that can be invoved in
  838    transfers. 
  839    I think I have to write a blog post one day of how this works and affects
  840    performance. tl;dr the more handles http2 may use, the faster static files
  841    can be served.
  842  * KeepAlive is not correctly visible on the server status page for HTTP/2
  843    connections. (Would like more info there, need to extend the scoreboard
  844    for it.)
  845  * KeepAlive connections are *not* set aside in async MPMs such as event. This
  846    is a very desirable feature, but I could not get it to work reliably with
  847    the existing MPM interface. Will work on that for the next Apache release.
  848    (The main problem is that event will silently close such connections and
  849     http2 has no chance to send a last GOAWAY frame. That makes clients fail
  850     requests which they have just started.)
  851 
  852 v1.0.18
  853 -------------------------------------------------------------------------------- 
  854  * fixed race condition in connnection shutdown that could cause indefinite 
  855    hang, fixed cleanup of http2 worker threads, thanks to Yann Ylavic
  856  
  857 v1.0.17
  858 -------------------------------------------------------------------------------- 
  859  * H2Timeout/H2KeepAliveTimeout now defaults to what ever is set for HTTP/1
  860    connections via Timeout/KeepAliveTimeout
  861  * fixes in calculating remaining timeout values
  862 
  863 v1.0.16
  864 -------------------------------------------------------------------------------- 
  865  * simplified connection shutdown and worker join for robustness
  866  * improved performance for small requests due to less locking
  867  * http2 connections work in event with normal server KeepAliveTimeout setting
  868  
  869 v1.0.15
  870 -------------------------------------------------------------------------------- 
  871  * fixed busy loops on random connection errors
  872  * fixed connection state for event MPM that shutdown child with 'G' status
  873  * changed default for H2KeepAliveTimeout. For async MPMs (event), will leave
  874    keepalive handling to the MPM. For sync (worker, prefork), will default to
  875    whatever is set for H2Timeout.
  876  
  877 v1.0.14
  878 -------------------------------------------------------------------------------- 
  879  * fixed segfault on connection shutdown
  880  * added support for accept-push-policy headers, see
  881    https://tools.ietf.org/html/draft-ruellan-http-accept-push-policy-00
  882  
  883 v1.0.13
  884 -------------------------------------------------------------------------------- 
  885  * reworked connection state handling. Improved scoreboard update (server-status).
  886    Default on H2KeepAliveTimeout same as H2Timeout, 5 seconds. After that, 
  887    connections are closed.
  888    On asynchronous MPMs (event), keep-alive connections no longer block threads,
  889    but exact timeout handling is then up to the MPM. In these MPMs, having a
  890    longer H2KeepAliveTimeout may be suitable.
  891  * new CGI environment variables HTTP2 and H2PUSH. With former "on", the 
  892    connection uses HTTP/2. With latter "on", the request may trigger Server Push
  893    via Link headers, as both server and clients support it.
  894 
  895 v1.0.12
  896 -------------------------------------------------------------------------------- 
  897  * alpha release on top of Apache httpd 2.4.18
  898  * removed sandbox from build, needs installed 2.4.18 + apxs
  899  * new directives:
  900    - H2Timeout           timeout of a http/2 connection (seconds), default 5
  901    - H2KeepAliveTimeout  timeout of an idle http/2 connection (seconds), default 300
  902    - H2StreamTimeout     timeout on individual streams (seconds), default 120
  903    you can set them to `0` in which case no timeout may apply. You may try that
  904    for the stream timeouts if you have problems. This is the very experimental
  905    part right now...
  906  * improved handling of connection closes to make a better effort on freeing
  907    worker threads still involved in streams.
  908  * worker numbers are constant MaxThreadsPerChild by default
  909  * fixed bug on handling large input without content length
  910    
  911 v1.0.3
  912 -------------------------------------------------------------------------------- 
  913  * copy from https://svn.apache.org/repos/asf/httpd/httpd/trunk
  914  * includes proposed backport patch for Apache httpd 2.4.17
  915    * improved https:// throughput
  916    * vastly improved http:// throughput
  917    * several stability and logging improvements
  918    * connection reuse: virtual hosts that have exactly the same TLS setup
  919      (certificates, protocol, ciphers and all) allow using a single HTTP/2
  920      connection.
  921    * h2c: first HTTP/1.1 request on a connection will announce additionally
  922      available and more preferred protocols in the ```Upgrade``` response
  923      header.
  924    * H2Direct is by default on for cleartext connections where h2c is an
  925      allowed protocol. Or, the other way around, it is always disabled unless
  926      h2/h2c is configured.
  927    * TLS handshake is triggered earlier, allowing all connection hooks which
  928      register behind mod_ssl to see negotiated values.
  929    * new experimental directives ```H2TLSWarmUpSize``` and ```H2TLSCoolDownSecs```
  930      that specify how TLS record sizes should used during the lifetime of a
  931      connection.
  932      * H2TLSWarmUpSize: amount of bytes to send in small (~1300 bytes) chunks,
  933        so that packets fit inside a single MTU. After this many bytes have
  934        been sent, data is written with max size of 16 KB when possible.
  935      * H2TLSCoolDownSecs: number of idle seconds to pass before a warmed
  936        up TLS connection falls back to small chunks again.
  937      Set both to 0 to always write max chunks. Defaults are 1 MB and 1 second.
  938    * HTTP/2 priorities are now respected when scheduling streams for handling.
  939      This effects which queued task is handled first whenever a worker becomes
  940      available.
  941    * New directive ```H2ModernTLSOnly on|off``` that checks connections for
  942      TLS protocol version and negotiated ciphers, so that HTTP/2 connections
  943      only happen on ```modern``` TLS and none of the ciphers in the black
  944      list from RFC 7540 are used.
  945    * 'HTTP/2.0' is written in log files when requests are served via mod_http2.
  946      
  947  * updated test cases from Apache tests
  948  * configure now builds the sandbox by default, too many user problems
  949    otherwise
  950 
  951 
  952 v0.9.9 - 1.0.2
  953 -------------------------------------------------------------------------------- 
  954 never happened here, but at http://httpd.apache.org
  955 
  956 v0.9.8
  957 -------------------------------------------------------------------------------- 
  958  * server protocol of requests served via mod_h2 is now `HTTP/2`
  959  * directive `H2SerializeHeaders` had no effect any longer, fixed.
  960  * requests served in `H2SerializeHeaders on` hosts, report `HTTP/1.1` as
  961    protocol. This is the mode to enabled when having compatiblity issues.
  962 
  963 v0.9.7
  964 -------------------------------------------------------------------------------- 
  965  * update of core-protocols.patch to v4
  966  * "Protocols" default changed. servers/vhosts need to explicitly enable h2/h2c 
  967    now. For example with `Protocols h2 http/1.1`
  968  * adding test cases for "Protocols" ordering
  969  * configuration option -enable-werror now sets compiler flags to go for Apache
  970    httpd standard code restrictions.
  971 
  972 v0.9.6
  973 -------------------------------------------------------------------------------- 
  974  * for closed h2 connections proper state is set. Fixes resource/worker handling
  975    issues in mpm_event
  976  * upgrade the core-protocols patch to the latest relevant apache changes
  977  * if not explicitly configured, H2SessionExtraFiles gets a default usable in
  978    proecsses with 256 max file handles and depending on mpm used.
  979  * upgraded sandbox to nghttp2 1.3.0
  980 
  981 v0.9.5
  982 -------------------------------------------------------------------------------- 
  983  * fix for resource management when running with mpm_event
  984 
  985 v0.9.4
  986 -------------------------------------------------------------------------------- 
  987  * mod_h2 is a copy of the module in Apache httpd trunk
  988  * requires a patched httpd for new Protocols feature. Patch applied in sandbox,
  989    available for own use in sandbox/httpd/patches/core_protocols_release.patch.
  990  * See README.me about changes, especially the chapter about Migration
  991  * Several H2* directives have disappeared, also see Migration in README.md
  992  * This version should be close to the release candidate. Report any issues
  993    here at github or on the apache httpd dev mailing list
  994 
  995 v0.8.3
  996 -------------------------------------------------------------------------------- 
  997  * Fixed typo in module setup during installation that broke enabling the module
  998    via a2enmod.
  999 
 1000 v0.8.2
 1001 -------------------------------------------------------------------------------- 
 1002  * In case "H2SerializeHeaders On" is configured, errorneous requests led to
 1003    500 responses. Fixed by installing post_read hooks really early now.
 1004 
 1005 v0.8.1
 1006 -------------------------------------------------------------------------------- 
 1007  * added some defensive code for configurations at user that produced duplicate
 1008    response headers
 1009  * added httpd/trunk fix to allocate task memory pools under mplx locking
 1010 
 1011 v0.8.0
 1012 -------------------------------------------------------------------------------- 
 1013  * when serving static files, these are kept open longer (and buffer copied
 1014    less). Use config "H2SessionExtraFiles" to change the value. The more you
 1015    can give per connection, the better. But you may run out of open file 
 1016    handles, if not careful. Default value is 5, which seems to work on my
 1017    config with mpms worker, event and prefork. Basically, eaach httpd process
 1018    needs at least #connections + #workers + (#conn * #extrafiles) available.
 1019  * main connection buffering, buffer sizes and write sizes are configurable,
 1020    see README.md for the list of options. buffer sizes and write sizes influence
 1021    the TLS performance. Defaults seem reasonably, but ymmv.
 1022  * general performance improved due to better handling of stream close and
 1023    resource cleanup
 1024  * prefork mpm confirmed working. Unless configured otherwise, each session
 1025    will only have 1 worker thread. Raise this with "H2MaxWorkers"
 1026  * changed sandbox cipher config to mozilla recommendation (thanks Lucas)
 1027  * sandbox update to nghttp2 1.0.5
 1028 
 1029 v0.7.3
 1030 --------------------------------------------------------------------------------
 1031  * sandbox update to nghttp2 1.0.4
 1032  * rework of stream scheduling and thread sync
 1033  * test suite runs with mpm_prefork on OS X and Ubuntu (feedback welcome)
 1034 
 1035 v0.7.2
 1036 --------------------------------------------------------------------------------
 1037  * fixes crash with certain modules that (correctly) expected their 
 1038    pre_connection hooks to work. Solves #28
 1039  * fixes log statements and Makefile to compile sandbox on 32bit linux
 1040 
 1041 v0.7.1
 1042 --------------------------------------------------------------------------------
 1043  * h2_mplx now uses reference counting to enable a controlled destruction on
 1044    session termination. If this fixes all the crashes reported, remains to
 1045    be seen.
 1046 
 1047 v0.7.0
 1048 --------------------------------------------------------------------------------
 1049  * switching to nghttp2 v1.0.*, compilation + linkage with nghttp2 v0.7.* will
 1050    not work any more as there have been changes in nghttp2's API. The sandbox
 1051    builds against v1.0.2 and also pulls curl 7.43.0 which did the same version
 1052    switch.
 1053  * keeping support for h2-16/h2-14 ALPN identifiers until a 1.0 release
 1054  * varying h2 support (on|off) among virtual hosts on the same port is now
 1055    possible and should work correctly.
 1056  * improved mod_ssl alpn patch to correctly select the proper virtual host
 1057    even if the SSL library invokes SNI after ALPN callbacks.
 1058  * Disabled NPN support in sandbox built. The patch for httpd 2.4.x is still
 1059    there, but no longer applied.
 1060  * KNOWN ISSUE: when using mpm_event, the error 
 1061      "error scoreboard is full, not at MaxRequestWorkers" 
 1062    sometimes happens. Under investigation. mpm_worker ist stable and recommended
 1063    for now.
 1064 
 1065 
 1066 v0.6.6
 1067 --------------------------------------------------------------------------------
 1068  * adding sni_misdirect.patch for httpd/mod_ssl that changes status code when 
 1069    TLS connections are reused for other vhosts. 
 1070 
 1071 v0.6.5
 1072 --------------------------------------------------------------------------------
 1073  * httpd scoreboard fixups: scoreboard handles are still updated on the main
 1074    connection from all stream request incoming from it, since it is not trivial
 1075    to get new handles for h2 workers. Updating of scoreboard status has been 
 1076    improved, no workers remain on "G"raceful shutdown in load tests any longer.
 1077  * some refacoring to isolate tls/alpn/upgrade code
 1078  * adding php-wrapper script to distribution, was missing
 1079 
 1080 v0.6.4
 1081 --------------------------------------------------------------------------------
 1082  * accepting "h2" on Upgrade: headers and allowing also Upgrade to work on TLS
 1083    connections that talk HTTP/1.1.
 1084  * logging WARNING once when mod_h2 is used in a "prefork" mpm configuration.
 1085    There seem to be issues with mod_proxy/rewrite and dankging I/O.
 1086  * added test suites for combinations with mod_proxy and mod_rewrite
 1087  * added test for request with Host: header where h2 is not enabled
 1088  * sandbox now builds local openssl 1.0.2 if 1.0.1 or older are installed
 1089    on the system. Prior 1.0.1 was accepted, but NPN support will be disabled
 1090    soon.
 1091  * added "Known Problems" section in README
 1092  * direct mode should also work with TLS connections, untested currently.
 1093 
 1094 v0.6.3
 1095 --------------------------------------------------------------------------------
 1096  * h2c direct mode is now enabled on http: virtual hosts. It can be disabled
 1097    by configuring "H2Direct off" for the base server. This works for clients
 1098    with prior knowledge that a http server supports h2c.
 1099 
 1100 v0.6.2
 1101 --------------------------------------------------------------------------------
 1102  * added "H2Direct (on|off)" as config directive. On a non-TLS host, it enables
 1103    direct h2c communication without any Upgrade dance. Useful for testing, for
 1104    example with h2load.
 1105  * fixed concurrency issue observed on a mpm_event server when closing sessions
 1106 
 1107 v0.6.1
 1108 --------------------------------------------------------------------------------
 1109  * relaxing task finished sync due to segfaults with mpm_event
 1110  * mod_reqtimeout enabled on stream processing again
 1111  * merged pr from ecovener, fix for ap_update_vhost_from_headers use
 1112  * tinkering with buffering on main connection
 1113 
 1114 v0.6.0
 1115 --------------------------------------------------------------------------------
 1116  * fiddling around with task/worker assignments to use the global h2_workers
 1117    lock less, giving better parallelism
 1118  * ./configure --enable-werror enables all sorts of compiler diagnostics, if
 1119    the chosen compiler supports them
 1120  * merged pull request with compiler warning fixes by LPardue and @samhurst 
 1121    (Thanks!)
 1122  * new config option "H2SerializeHeaders (On|Off)" that determines if request
 1123    response headers should be serialized/parsed when converting from HTTP/2 to
 1124    httpd's internal HTTP/1 processing or request_recs are manipulated directly.
 1125    "Off" is default, "On" gives better compatibility.
 1126  * new config options "H2HackMpmEvent (On|Off) that enables a hack to make
 1127    internal connection work with the mpm_event module. Has no effect if other
 1128    mpm modules have been configured. Defaults to "On"."
 1129  * upgrading sandbox to nghttp2 0.7.15
 1130 
 1131 v0.5.6
 1132 --------------------------------------------------------------------------------
 1133  * making SSL variables available in subprocess (e.g. CGI) environments if
 1134 configured (fixes #19)
 1135 
 1136 v0.5.5
 1137 --------------------------------------------------------------------------------
 1138  * improved transfer of large resources by 50% by more efficient writes
 1139 
 1140 v0.5.4
 1141  --------------------------------------------------------------------------------
 1142  * moving request handling and http/1 emulation into worker thread, offloading 
 1143    main
 1144  * some fixes in connection shutdown re race condition with still active workers
 1145  * removing reqtimeout filters on stream connections
 1146  * taking in latest alpn changes from httpd trunk, made separate npn patch for
 1147    those who need to run with openssl 1.0.1
 1148  * fixed handling of transient bucket in stream output data (led to corrupted
 1149    responses)
 1150  * reworked task join to eliminate race conditions during session shutdown
 1151  * info logging is less verbose
 1152 
 1153 v0.5.2
 1154 --------------------------------------------------------------------------------
 1155  * rewrote the input handling
 1156     * forwarding headers in camel case to HTTP/1 request prossing
 1157     * merging duplicate headers into single line with proper separators
 1158     * eliminated h2_bucket by using apr_bucket_brigades everywhere
 1159     * added test cases and fixed chunked input processing
 1160  * sandbox now uses curl 7.42.0
 1161  * enhanced alpn patch slightly, compatible to old one, no need to repatch mod_ssl on existing installations
 1162  * adding some tests with fcgi, for sandbox testing please install php5-cgi
 1163 
 1164 v0.5.1
 1165 --------------------------------------------------------------------------------
 1166  * ensuring HOST header is properly set for internal request handling
 1167  * updated sandbox to latest nghttp2 release
 1168 
 1169 v0.5.0
 1170 --------------------------------------------------------------------------------
 1171  * improved resource handling and performance
 1172  * fixes lookup of correct server config when several virtual hosts are 
 1173    available
 1174 
 1175 v0.4.5
 1176 --------------------------------------------------------------------------------
 1177  * fixed base64 decoding to use correct dialect when upgrading to h2c
 1178 
 1179 v0.4.4
 1180 --------------------------------------------------------------------------------
 1181  * adds missing file in distribution tar, fixes #11
 1182  * sandbox now uses nghttp2 0.7.11
 1183 
 1184 v0.4.3
 1185 --------------------------------------------------------------------------------
 1186  * heavy work on internal data transfers, use of apache bucket brigades for
 1187    improved performance and parallelism
 1188  * mod_h2 now performs proper flow-control on input. Uploads can no longer
 1189    flood memory of the server.
 1190  * changed mod_ssl patch to reflect current trunk changes in regard to NPN/ALPN
 1191    support.
 1192  * patched the trunk ALPN patch to make it do the right thing if no 
 1193    ALPNPreference is configured
 1194  * added DESTDIR support in Makefile as supplied by Hanno Böck.
 1195 
 1196 v0.4.2
 1197 --------------------------------------------------------------------------------
 1198  * adding more low-level logging to NPN/ALPN negotiation
 1199  * added '-Werror' to module compiler flags (thanks @devurandom)
 1200  * debugged and tcpdumped around h2c startup handling with curl on certain
 1201    platforms. If you experience connection hangers, report pls with 'trace2'
 1202    level error log.
 1203 
 1204 v0.4.1
 1205 --------------------------------------------------------------------------------
 1206  * fixing infinite loop when aborting session with tasks hanging in read
 1207 
 1208 v0.4.0
 1209 --------------------------------------------------------------------------------
 1210  * h2 + h2-16 will be negiotiated/upgraded. Priority handling is implemented
 1211    in nghttp2, however assigning requests to workers has currently not the
 1212    necessary information.
 1213  * Alt-Svc support based on https://http2.github.io/http2-spec/alt-svc.html#indicator
 1214    Configuration directives "H2AltSvc" and "H2AltSvcMaxAge" added. Configurable
 1215    per virtual host.
 1216  * reduced lock contention and eliminated broadcast signalling on internal 
 1217    condition variables, improved multi-thread performance
 1218 
 1219 v0.3.1
 1220 --------------------------------------------------------------------------------
 1221  * defining _GNU_SOURCE to pull in proper features and make APR header files
 1222    happy, fixes #7 
 1223 
 1224 v0.3.0
 1225 --------------------------------------------------------------------------------
 1226  * new directory structure, all sandbox related parts have been moved to 
 1227    own sandbox dir
 1228  * non-sandbox configuration no longer triggers building of sandbox stuff
 1229  * cleanup up distribution builds to have smaller and working tar balls
 1230 
 1231 v0.2.2
 1232 --------------------------------------------------------------------------------
 1233  * optimizations on response reads
 1234  * being more apacheeeish, using APR_RINGs for queue handling
 1235  * using openssl latest.tar.gz to retrieve latest openssl for sandbox
 1236  * fixed crash in large request header handling
 1237  * better flushing of stream io resulting in performance improvements
 1238  * added sandbox tests for chunked responses of various sizes
 1239  * integrated fix (https://github.com/icing/mod_h2/pull/5) from 
 1240    Jonathan (invader444) to fix chunked encoding when converting http/1
 1241    responses to http2 unchunked data.
 1242 
 1243 v0.2.1
 1244 --------------------------------------------------------------------------------
 1245  * changed apr_pool usage to have more recycling, 50% performance increase in 
 1246    loadtest
 1247  * added hack to enable mod_h2 to run in mpm_event (experimental)
 1248  * changed internal stream/data lookup from O(n/2) to O(log(n)) time
 1249  * fixed index in http2 to http1 header conversion leading to segfaults
 1250  * update openssl version downloaded for sandbox
 1251  * using sha256 for self-signed sandbox certificates
 1252  * sandbox certificate no longer announces itself as roo
 1253    (last 3 thanks to michael.koeller at greenbytes.de)
 1254 
 1255 v0.2.0
 1256 --------------------------------------------------------------------------------
 1257  * merged pull request from Tatsuhiro Tsujikawa, removing code for CONTINUATION
 1258    frames that are never seen by mod_h2
 1259  * request/response headers are filtered when converting between HTTP/1.1 and
 1260    HTTP/2 where they can only do harm (Expect/Connection/etc.)
 1261  * added test cases for uploads
 1262  * fixed handling of uploads ;-)
 1263  * enabled h2c upgrade for "OPTIONS *" requests
 1264  * changed h2_stream_set implementation to use sorted apr array
 1265  * switched to nghttp2 v0.7.7 in sandbox
 1266 
 1267 v0.1.1
 1268 --------------------------------------------------------------------------------
 1269  * added cgi test cases (needs python installed)
 1270  * fixed typo in configure.ac that did not set the CPP flags correctly (#3)
 1271  * fixed handling of chunked encoding in responses
 1272  * merged header macro pull request from MATSUMOTO, Ryosuke
 1273 
 1274 v0.1.0
 1275 --------------------------------------------------------------------------------
 1276  * first alpha release, see README on how to use it and what is all missing
 1277  * h2 supported with openssl > 1.0.1 and patched mod_ssl (patch included and used in sandbox)
 1278  * h2c supported
 1279  * only usable in mpm_worker right now
 1280  * configure --enable-sandbox for a local install of everything needed
 1281  * tested with httpd 2.4.12 and nghttp2 0.7.5 on Ubuntu 14.04 and OS X 10.10