                                                         -*- coding: utf-8 -*-
Changes with Apache 2.4.52

  *) http: Enforce that fully qualified uri-paths not to be forward-proxied
     have an http(s) scheme, and that the ones to be forward proxied have a
     hostname, per HTTP specifications.  [Ruediger Pluem, Yann Ylavic]

  *) OpenSSL autoconf detection improvement: pick up openssl.pc in the
     specified openssl path. [Joe Orton]

  *) mod_proxy_connect, mod_proxy: Do not change the status code after we
     already sent it to the client.

  *) mod_http: Correctly sent a 100 Continue status code when sending an interim
     response as result of an Expect: 100-Continue in the request and not the
     current status code of the request. PR 65725 [Ruediger Pluem]

  *) mod_dav: Some DAV extensions, like CalDAV, specify both document
     elements and property elements that need to be taken into account
     when generating a property. The document element and property element
     are made available in the dav_liveprop_elem structure by calling
     dav_get_liveprop_element(). [Graham Leggett]

  *) mod_dav: Add utility functions dav_validate_root_ns(),
     dav_find_child_ns(), dav_find_next_ns(), dav_find_attr_ns() and
     dav_find_attr() so that other modules get to play too.
     [Graham Leggett]

  *) mpm_event: Restart stopping of idle children after a load peak. PR 65626.
     [Yann Ylavic, Ruediger Pluem]

  *) mod_http2: fixes 2 regressions in server limit handling.
     1. When reaching server limits, such as MaxRequestsPerChild, the
        HTTP/2 connection send a GOAWAY frame much too early on new
        connections, leading to invalid protocol state and a client
        failing the request. See PR65731.
        The module now initializes the HTTP/2 protocol correctly and
        allows the client to submit one request before the shutdown
        via a GOAWAY frame is being announced.
     2. A regression in v1.15.24 was fixed that could lead to httpd
        child processes not being terminated on a graceful reload or
        when reaching MaxConnectionsPerChild. When unprocessed h2
        requests were queued at the time, these could stall.
        See <https://github.com/icing/mod_h2/issues/212>.
     [Stefan Eissing]

  *) mod_ssl: Add build support for OpenSSL v3. [Rainer Jung,
     Stefan Fritsch, Yann Ylavic, Stefan Eissing, Joe Orton,
     Giovanni Bechis]

  *) mod_proxy_connect: Honor the smallest of the backend or client timeout
     while tunneling.  [Yann Ylavic]

  *) mod_proxy: SetEnv proxy-nohalfclose (or alike) allows to disable TCP
     half-close forwarding when tunneling protocols.  [Yann Ylavic]

  *) core: Be safe with ap_lingering_close() called with a socket NULL-ed by
     a third-party module.  PR 65627.
     [acmondor <bz.apache.org acmondor.ca>, Yann Ylavic]

  *) mod_md: Fix memory leak in case of failures to load the private key.
     PR 65620 [ Filipe Casal <filipe.casal@trailofbits.com> ]

  *) mod_md: adding v2.4.8 with the following changes
    - Added support for ACME External Account Binding (EAB).
      Use the new directive `MDExternalAccountBinding` to provide the
      server with the value for key identifier and hmac as provided by
      your CA.
      While working on some servers, EAB handling is not uniform
      across CAs. First tests with a Sectigo Certificate Manager in
      demo mode are successful. But ZeroSSL, for example, seems to
      regard EAB values as a one-time-use-only thing, which makes them
      fail if you create a seconde account or retry the creation of the
      first account with the same EAB.
    - The directive 'MDCertificateAuthority' now checks if its parameter
      is a http/https url or one of a set of known names. Those are
      'LetsEncrypt', 'LetsEncrypt-Test', 'Buypass' and 'Buypass-Test'
      for now and they are not case-sensitive.
      The default of LetsEncrypt is unchanged.
    - `MDContactEmail` can now be specified inside a `<MDomain dnsname>`
      section.
    - Treating 401 HTTP status codes for orders like 403, since some ACME
      servers seem to prefer that for accessing oders from other accounts.
    - When retrieving certificate chains, try to read the repsonse even
      if the HTTP Content-Type is unrecognized.
    - Fixed a bug that reset the error counter of a certificate renewal
      and prevented the increasing delays in further attempts.
    - Fixed the renewal process giving up every time on an already existing
      order with some invalid domains. Now, if such are seen in a previous
      order, a new order is created for a clean start over again.
      See <https://github.com/icing/mod_md/issues/268>
    - Fixed a mixup in md-status handler when static certificate files
      and renewal was configured at the same time.

  *) mod_md: values for External Account Binding (EAB) can
     now also be configured to be read from a separate JSON
     file. This allows to keep server configuration permissions
     world readable without exposing secrets.
     [Stefan Eissing]

  *) mod_proxy_uwsgi: Remove duplicate slashes at the beginning of PATH_INFO.
     PR 65616.  [Ruediger Pluem]

Changes with Apache 2.4.51

  *) SECURITY: CVE-2021-42013: Path Traversal and Remote Code
     Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete
     fix of CVE-2021-41773) (cve.mitre.org)
     It was found that the fix for CVE-2021-41773 in Apache HTTP
     Server 2.4.50 was insufficient.  An attacker could use a path
     traversal attack to map URLs to files outside the directories
     configured by Alias-like directives.
     If files outside of these directories are not protected by the
     usual default configuration "require all denied", these requests
     can succeed. If CGI scripts are also enabled for these aliased
     pathes, this could allow for remote code execution.
     This issue only affects Apache 2.4.49 and Apache 2.4.50 and not
     earlier versions.
     Credits: Reported by Juan Escobar from Dreamlab Technologies,
     Fernando Muñoz from NULL Life CTF Team, and Shungo Kumasaka

  *) core: Add ap_unescape_url_ex() for better decoding control, and deprecate
     unused AP_NORMALIZE_DROP_PARAMETERS flag.
     [Yann Ylavic, Ruediger Pluem, Stefan Eissing, Joe Orton]

Changes with Apache 2.4.50

  *) SECURITY: CVE-2021-41773: Path traversal and file disclosure
     vulnerability in Apache HTTP Server 2.4.49 (cve.mitre.org)
     A flaw was found in a change made to path normalization in
     Apache HTTP Server 2.4.49. An attacker could use a path
     traversal attack to map URLs to files outside the expected
     document root.
     If files outside of the document root are not protected by
     "require all denied" these requests can succeed. Additionally
     this flaw could leak the source of interpreted files like CGI
     scripts.
     This issue is known to be exploited in the wild.
     This issue only affects Apache 2.4.49 and not earlier versions.
     Credits: This issue was reported by Ash Daulton along with the
     cPanel Security Team

  *) SECURITY: CVE-2021-41524: null pointer dereference in h2 fuzzing
     (cve.mitre.org)
     While fuzzing the 2.4.49 httpd, a new null pointer dereference
     was detected during HTTP/2 request processing,
     allowing an external source to DoS the server. This requires a
     specially crafted request.
     The vulnerability was recently introduced in version 2.4.49. No
     exploit is known to the project.
     Credits: Apache httpd team would like to thank LI ZHI XIN from
     NSFocus Security Team for reporting this issue.

  *) core: AP_NORMALIZE_DECODE_UNRESERVED should normalize the second dot in
     the uri-path when it's preceded by a dot.  [Yann Ylavic]

  *) mod_md: when MDMessageCmd for a 'challenge-setup:<type>:<dnsname>'
     fails (!= 0 exit), the renewal process is aborted and an error is
     reported for the MDomain. This provides scripts that distribute
     information in a cluster to abort early with bothering an ACME
     server to validate a dns name that will not work. The common
     retry logic will make another attempt in the future, as with
     other failures.
     Fixed a bug when adding private key specs to an already working
     MDomain, see <https://github.com/icing/mod_md/issues/260>.
     [Stefan Eissing]

  *) mod_proxy: Handle UDS URIs with empty hostname ("unix:///...") as if they
     had no hostname ("unix:/...").  [Yann Ylavic]

  *) mod_md: fixed a bug in handling multiple parallel OCSP requests. These could
     run into an assertion which terminated (and restarted) the child process where
     the task was running. Eventually, all OCSP responses were collected, but not
     in the way that things are supposed to work.
     See also <https://bz.apache.org/bugzilla/show_bug.cgi?id=65567>.
     The bug was possibly triggered when more than one OCSP status needed updating
     at the same time. For example for several renewed certificates after a server
     reload.

  *) mod_rewrite: Fix UDS ("unix:") scheme for [P] rules.  PR 57691 + 65590.
     [Janne Peltonen <janne.peltonen sange.fi>]

  *) event mpm: Correctly count active child processes in parent process if
     child process dies due to MaxConnectionsPerChild.
     PR 65592 [Ruediger Pluem]

  *) mod_http2: when a server is restarted gracefully, any idle h2 worker
     threads are shut down immediately.
     Also, change OpenSSL API use for deprecations in OpenSSL 3.0.
     Adds all other, never proposed code changes to make a clean
     sync of http2 sources. [Stefan Eissing]

  *) mod_dav: Correctly handle errors returned by dav providers on REPORT
     requests. [Ruediger Pluem]

  *) core: do not install core input/output filters on secondary
     connections. [Stefan Eissing]

  *) core: Add ap_pre_connection() as a wrapper to ap_run_pre_connection()
     and use it to prevent that failures in running the pre_connection
     hook cause crashes afterwards. [Ruediger Pluem]

  *) mod_speling: Add CheckBasenameMatch PR 44221.  [Christophe Jaillet]

Changes with Apache 2.4.49

  *) SECURITY: CVE-2021-40438 (cve.mitre.org)
     mod_proxy: Server Side Request Forgery (SSRF) vulnerabilty [Yann Ylavic]

  *) SECURITY: CVE-2021-39275 (cve.mitre.org)
     core: ap_escape_quotes buffer overflow

  *) SECURITY: CVE-2021-36160 (cve.mitre.org)
     mod_proxy_uwsgi: Out of bound read vulnerability [Yann Ylavic]

  *) SECURITY: CVE-2021-34798 (cve.mitre.org)
     core: null pointer dereference on malformed request

  *) SECURITY: CVE-2021-33193 (cve.mitre.org)
     mod_http2: Request splitting vulnerability with mod_proxy [Stefan Eissing]

  *) core/mod_proxy/mod_ssl:
     Adding `outgoing` flag to conn_rec, indicating a connection is
     initiated by the server to somewhere, in contrast to incoming
     connections from clients.
     Adding 'ap_ssl_bind_outgoing()` function that marks a connection
     as outgoing and is used by mod_proxy instead of the previous
     optional function `ssl_engine_set`. This enables other SSL
     module to secure proxy connections.
     The optional functions `ssl_engine_set`, `ssl_engine_disable` and
     `ssl_proxy_enable` are now provided by the core to have backward
     compatibility with non-httpd modules that might use them. mod_ssl
     itself no longer registers these functions, but keeps them in its
     header for backward compatibility.
     The core provided optional function wrap any registered function
     like it was done for `ssl_is_ssl`.
     [Stefan Eissing]

  *) mod_ssl: Support logging private key material for use with
     wireshark via log file given by SSLKEYLOGFILE environment
     variable.  Requires OpenSSL 1.1.1.  PR 63391.  [Joe Orton]

  *) mod_proxy: Do not canonicalize the proxied URL when both "nocanon" and
     "ProxyPassInterpolateEnv On" are configured.  PR 65549.
     [Joel Self <joelself gmail.com>]

  *) mpm_event: Fix children processes possibly not stopped on graceful
     restart.  PR 63169.  [Joel Self <joelself gmail.com>]

  *) mod_proxy: Fix a potential infinite loop when tunneling Upgrade(d)
     protocols from mod_proxy_http, and a timeout triggering falsely when
     using mod_proxy_wstunnel, mod_proxy_connect or mod_proxy_http with
     upgrade= setting.  PRs 65521 and 65519.  [Yann Ylavic]

  *) mod_unique_id: Reduce the time window where duplicates may be generated
     PR 65159
     [Christophe Jaillet]

  *) mpm_prefork: Block signals for child_init hooks to prevent potential
     threads created from there to catch MPM's signals.
     [Ruediger Pluem, Yann Ylavic]

  *) Revert "mod_unique_id: Fix potential duplicated ID generation under heavy load.
     PR 65159" added in 2.4.47.
     This causes issue on Windows.
     [Christophe Jaillet]

  *) mod_proxy_uwsgi: Fix PATH_INFO setting for generic worker.  [Yann Ylavic]

  *) mod_md: Certificate/keys pairs are verified as matching before a renewal is accepted
     as successful or a staged renewal is replacing the existing certificates.
     This avoid potential mess ups in the md store file system to render the active
     certificates non-working. [@mkauf]

  *) mod_proxy: Faster unix socket path parsing in the "proxy:" URL.
     [Yann Ylavic]

  *) mod_ssl: tighten the handling of ALPN for outgoing (proxy)
     connections. If ALPN protocols are provided and sent to the
     remote server, the received protocol selected is inspected
     and checked for a match. Without match, the peer handshake
     fails.
     An exception is the proposal of "http/1.1" where it is
     accepted if the remote server did not answer ALPN with
     a selected protocol. This accomodates for hosts that do
     not observe/support ALPN and speak http/1.x be default.

  *) mod_proxy: Fix possible reuse/merging of Proxy(Pass)Match worker instances
     with others when their URLs contain a '$' substitution.  PR 65419 + 65429.
     [Yann Ylavic]

  *) mod_dav: Add method_precondition hook. WebDAV extensions define
     conditions that must exist before a WebDAV method can be executed.
     This hook allows a WebDAV extension to verify these preconditions.
     [Graham Leggett]

  *) Add hooks deliver_report and gather_reports to mod_dav.h. Allows other
     modules apart from versioning implementations to handle the REPORT method.
     [Graham Leggett]

  *) Add dav_get_provider(), dav_open_lockdb(), dav_close_lockdb() and
     dav_get_resource() to mod_dav.h. [Graham Leggett]

  *) core: fix ap_escape_quotes substitution logic. [Eric Covener]

  *) core/mpm: add hook 'child_stopping` that gets called when the MPM is
     stopping a child process. The additional `graceful` parameter allows
     registered hooks to free resources early during a graceful shutdown.
     [Yann Ylavic, Stefan Eissing]

  *) mod_proxy: Fix icomplete initialization of BalancerMember(s) from the
     balancer-manager, which can lead to a crash.  [Yann Ylavic]

  *) mpm_event: Fix graceful stop/restart of children processes if connections
     are in lingering close for too long.  [Yann Ylavic]

  *) mod_md: fixed a potential null pointer dereference if ACME/OCSP
     server returned 2xx responses without content type. Reported by chuangwen.
     [chuangwen, Stefan Eissing]

  *) mod_md:
     - Domain names in `<MDomain ...>` can now appear in quoted form.
     - Fixed a failure in ACME challenge selection that aborted further searches
       when the tls-alpn-01 method did not seem to be suitable.
     - Changed the tls-alpn-01 setup to only become unsuitable when none of the
       dns names showed support for a configured 'Protocols ... acme-tls/1'. This
       allows use of tls-alpn-01 for dns names that are not mapped to a VirtualHost.
     [Stefan Eissing]

  *) Add CPING to health check logic. [Jean-Frederic Clere]

  *) core: Split ap_create_request() from ap_read_request(). [Graham Leggett]

  *) core, h2: common ap_parse_request_line() and ap_check_request_header()
     code. [Yann Ylavic]

  *) core: Add StrictHostCheck to allow unconfigured hostnames to be
     rejected. [Eric Covener]

  *) htcacheclean: Improve help messages.  [Christophe Jaillet]

Changes with Apache 2.4.48

  *) SECURITY: CVE-2021-31618 (cve.mitre.org)
     mod_http2: Fix a potential NULL pointer dereference [Ivan Zhakov]

  *) mod_proxy_wstunnel: Add ProxyWebsocketFallbackToProxyHttp to opt-out the
     fallback to mod_proxy_http for WebSocket upgrade and tunneling.
     [Yann Ylavic]

  *) mod_proxy: Fix flushing of THRESHOLD_MIN_WRITE data while tunneling.
     BZ 65294.  [Yann Ylavic]

  *) core: Fix a regression that stripped the ETag header from 304 responses.
     PR 61820 [Ruediger Pluem, Roy T. Fielding]

  *) core: Adding SSL related inquiry functions to the server API.
     These function are always available, even when no module providing
     SSL is loaded. They provide their own "shadowing" implementation for
     the optional functions of similar name that mod_ssl and impersonators
     of mod_ssl provide.
     This enables loading of several SSL providing modules when all but
     one of them registers itself into the new hooks. Two old-style SSL
     modules will not work, as they replace the others optional functions
     with their own.
     Modules using the old-style optional functions will continue to work
     as core supplies its own versions of those.
     The following has been added so far:
     - ap_ssl_conn_is_ssl() to query if a connection is using SSL.
     - ap_ssl_var_lookup() to query SSL related variables for a
       server/connection/request.
     - Hooks for 'ssl_conn_is_ssl' and 'ssl_var_lookup' where modules
       providing SSL can install their own value supplying functions.
     - ap_ssl_add_cert_files() to enable other modules like mod_md to provide
       certificate and keys for an SSL module like mod_ssl.
     - ap_ssl_add_fallback_cert_files() to enable other modules like mod_md to
       provide a fallback certificate in case no 'proper' certificate is
       available for an SSL module like mod_ssl.
     - ap_ssl_answer_challenge() to enable other modules like mod_md to
       provide a certificate as used in the RFC 8555 'tls-alpn-01' challenge
       for the ACME protocol for an SSL module like mod_ssl. The function
       and its hook provide PEM encoded data instead of file names.
     - Hooks for 'ssl_add_cert_files', 'ssl_add_fallback_cert_files' and
       'ssl_answer_challenge' where modules like mod_md can provide providers
       to the above mentioned functions.
     - These functions reside in the new 'http_ssl.h' header file.
     [Stefan Eissing]

  *) core/mod_ssl/mod_md: adding OCSP response provisioning as core feature. This
     allows modules to access and provide OCSP response data without being tied
     of each other. The data is exchanged in standard, portable formats (PEM encoded
     certificates and DER encoded responses), so that the actual SSL/crypto
     implementations used by the modules are independant of each other.
     Registration and retrieval happen in the context of a server (server_rec)
     which modules may use to decide if they are configured for this or not.
     The area of changes:
     1. core: defines 2 functions in include/http_ssl.h, so that modules may
        register a certificate, together with its issuer certificate for OCSP
        response provisioning and ask for current response data (DER bytes) later.
        Also, 2 hooks are defined that allow modules to implement this OCSP
        provisioning.
     2. mod_ssl uses the new functions, in addition to what it did already, to
        register its certificates this way. If no one is interested in providing
        OCSP, it falls back to its own (if configured) stapling implementation.
     3. mod_md registers itself at the core hooks for OCSP provisioning. Depending
        on configuration, it will accept registrations of its own certificates only,
        all certificates or none.
     [Stefan Eissing]

 *) mod_md: v2.4.0 with improvements and bugfixes
     - MDPrivateKeys allows the specification of several types. Beside "RSA" plus
     optional key lengths elliptic curves can be configured. This means you can
     have multiple certificates for a Managed Domain with different key types.
     With ```MDPrivateKeys secp384r1 rsa2048``` you get one ECDSA  and one RSA
     certificate and all modern client will use the shorter ECDSA, while older
     client will get the RSA certificate.
     Many thanks to @tlhackque who pushed and helped on this.
     - Support added for MDomains consisting of a wildcard. Configuring
     ```MDomain *.host.net``` will match all virtual hosts matching that pattern
     and obtain one certificate for it (assuming you have 'dns-01' challenge
     support configured). Addresses #239.
     - Removed support for ACMEv1 servers. The only known installation used to
     be Let's Encrypt which has disabled that version more than a year ago for
     new accounts.
     - Andreas Ulm (<https://github.com/root360-AndreasUlm>) implemented the
     ```renewing``` call to ```MDMessageCmd``` that can deny a certificate
     renewal attempt. This is useful in clustered installations, as
     discussed in #233).
     - New event ```challenge-setup:<type>:<domain>```, triggered when the
     challenge data for a domain has been created. This is invoked before the
     ACME server is told to check for it. The type is one of the ACME challenge
     types. This is invoked for every DNS name in a MDomain.
     - The max delay for retries has been raised to daily (this is like all
     retries jittered somewhat to avoid repeats at fixed time of day).
     - Certain error codes reported by the ACME server that indicate a problem
     with the configured data now immediately switch to daily retries. For
     example: if the ACME server rejects a contact email or a domain name,
     frequent retries will most likely not solve the problem. But daily retries
     still make sense as there might be an error at the server and un-supervised
     certificate renewal is the goal. Refs #222.
     - Test case and work around for domain names > 64 octets. Fixes #227.
     When the first DNS name of an MD is longer than 63 octets, the certificate
     request will not contain a CN field, but leave it up to the CA to choose one.
     Currently, Lets Encrypt looks for a shorter name in the SAN list given and
     fails the request if none is found. But it is really up to the CA (and what
     browsers/libs accept here) and may change over the years. That is why
     the decision is best made at the CA.
     - Retry delays now have a random +/-[0-50]% modification applied to let
     retries from several servers spread out more, should they have been
     restarted at the same time of day.
     - Fixed several places where the 'badNonce' return code from an ACME server
     was not handled correctly. The test server 'pebble' simulates this behaviour
     by default and helps nicely in verifying this behaviour. Thanks, pebble!
     - Set the default `MDActivationDelay` to 0. This was confusing to users that
     new certificates were deemed not usably before a day of delay. When clocks are
     correct, using a new certificate right away should not pose a problem.
     - When handling ACME authorization resources, the module no longer requires
     the server to return a "Location" header, as was necessary in ACMEv1.
     Fixes #216.
     - Fixed a theoretical uninitialized read when testing for JSON error responses
     from the ACME CA. Reported at <https://bz.apache.org/bugzilla/show_bug.cgi?id=64297>.
     - ACME problem reports from CAs that include parameters in the Content-Type
     header are handled correctly. (Previously, the problem text would not be
     reported and retries could exceed CA limits.)
     - Account Update transactions to V2 CAs now use the correct POST-AS-GET method.
     Previously, an empty JSON object was sent - which apparently LE accepted,
     but others reject.
     [Stefan Eissing, @tlhackque, Andreas Ulm]

Changes with Apache 2.4.47

  *) SECURITY: CVE-2021-30641 (cve.mitre.org)
     Unexpected <Location> section matching with 'MergeSlashes OFF'

  *) SECURITY: CVE-2020-35452 (cve.mitre.org)
     mod_auth_digest: possible stack overflow by one nul byte while validating
     the Digest nonce.  [Yann Ylavic]

  *) SECURITY: CVE-2021-26691 (cve.mitre.org)
     mod_session: Fix possible crash due to NULL pointer dereference, which
     could be used to cause a Denial of Service with a malicious backend
     server and SessionHeader.  [Yann Ylavic]

  *) SECURITY: CVE-2021-26690 (cve.mitre.org)
     mod_session: Fix possible crash due to NULL pointer dereference, which
     could be used to cause a Denial of Service.  [Yann Ylavic]

  *) SECURITY: CVE-2020-13950 (cve.mitre.org)
     mod_proxy_http: Fix possible crash due to NULL pointer dereference, which
     could be used to cause a Denial of Service.  [Yann Ylavic]

  *) SECURITY: CVE-2020-13938 (cve.mitre.org)
     Windows: Prevent local users from stopping the httpd process [Ivan Zhakov]

  *) SECURITY: CVE-2019-17567 (cve.mitre.org)
     mod_proxy_wstunnel, mod_proxy_http: Handle Upgradable protocols end-to-end
     negotiation.  [Yann Ylavic]

  *) mod_dav_fs: Improve logging output when failing to open files for
     writing.  PR 64413.  [Bingyu Shen <ahshenbingyu gmail.com>]

  *) mod_http2: Fixed a race condition that could lead to streams being
     aborted (RST to the client), although a response had been produced.
     [Stefan Eissing]

  *) mod_lua: Add support to Lua 5.4  [Joe Orton, Giovanni Bechis, Ruediger Pluem]

  *) MPM event/worker: Fix possible crash in child process on early signal
     delivery.  PR 64533.  [Ruediger Pluem]

  *) mod_http2: sync with github standalone version 1.15.17
     - Log requests and sent the configured error response in case of early detected
       errors like too many or too long headers. [Ruediger Pluem]
     - new option 'H2OutputBuffering on/off' which controls the buffering of stream output.
       The default is on, which is the behaviour of older mod-h2 versions. When off, all
       bytes are made available immediately to the main connection for sending them
       out to the client. This fixes interop issues with certain flavours of gRPC, see
       also <https://github.com/icing/mod_h2/issues/207>.
       [Stefan Eissing]

  *) mod_unique_id: Fix potential duplicated ID generation under heavy load.
     PR 65159
     [Jonas Müntener <jonas.muentener ergon.ch>, Christophe Jaillet]

  *) "[mod_dav_fs etag handling] should really honor the FileETag setting".
     - It now does.
     - Add "Digest" to FileETag directive, allowing a strong ETag to be
       generated using a file digest.
     - Add ap_make_etag_ex() and ap_set_etag_fd() to allow full control over
       ETag generation.
     - Add concept of "binary notes" to request_rec, allowing packed bit flags
       to be added to a request.
     - First binary note - AP_REQUEST_STRONG_ETAG - allows modules to force
       the ETag to a strong ETag to comply with RFC requirements, such as those
       mandated by various WebDAV extensions.
     [Graham Leggett]

  *) mod_proxy_http: Fix a possibly crash when the origin connection gets
     interrupted before completion.  PR 64234.
     [Barnim Dzwillo <dzwillo strato.de>, Ruediger Pluem]

  *) mod_ssl: Do not keep connections to OCSP responders alive when doing
     OCSP requests.  PR 64135.  [Ruediger Pluem]

  *) mod_ssl: Improve the coalescing filter to buffer into larger TLS
     records, and avoid revealing the HTTP header size via TLS record
     boundaries (for common response generators).
     [Joe Orton, Ruediger Pluem]     

  *) mod_proxy_hcheck: Don't pile up health checks if the previous one did
     not finish before hcinterval.  PR 63010.  [Yann Ylavic]

  *) mod_session: Improve session parsing.  [Yann Yalvic]

  *) mod_authnz_ldap: Prevent authentications with empty passwords for the
     initial bind to fail with status 500. [Ruediger Pluem]

  *) mod_proxy_fcgi: Honor "SetEnv proxy-sendcl" to forward a chunked
     Transfer-Encoding from the client, spooling the request body when needed
     to provide a Content-Length to the backend.  PR 57087.  [Yann Ylavic]

  *) mod_proxy: Improve tunneling loop to support half closed connections and
     pending data draining (for protocols like rsync). PR 61616. [Yann Ylavic]

  *) mod_proxy_wstunnel: Leave Upgrade requests handling to mod_proxy_http,
     allowing for (non-)Upgrade negotiation with the origin server.
     [Yann Ylavic]

  *) mod_proxy: Allow ProxyErrorOverride to be restricted to specific status 
     codes.  PR63628. [Martin Drößler <mail martindroessler.de>]

  *) core: Add ReadBufferSize, FlushMaxThreshold and FlushMaxPipelined
     directives.  [Yann Ylavic]

  *) core: Ensure that aborted connections are logged as such. PR 62823
     [Arnaud Grandville <contact@grandville.net>]

  *) http: Allow unknown response status' lines returned in the form of
     "HTTP/x.x xxx Status xxx".  [Yann Ylavic]

  *) mod_proxy_http: Fix 100-continue deadlock for spooled request bodies,
     leading to Request Timeout (408).  PR 63855.  [Yann Ylavic]

  *) core: Remove headers on 304 Not Modified as specified by RFC7234, as
     opposed to passing an explicit subset of headers. PR 61820.
     [Giovanni Bechis]

  *) mpm_event: Don't reset connections after lingering close, restoring prior
     to 2.4.28 behaviour.  [Yann Ylavic]

  *) mpm_event: Kill connections in keepalive state only when there is no more
     workers available, not when the maximum number of connections is reached,
     restoring prior to 2.4.30 behaviour.  [Yann Ylavic]

  *) mod_unique_id: Use base64url encoding for UNIQUE_ID variable,
     avoiding the use of '@'.  PR 57044.
     [Michael Kaufmann <apache-bugzilla michael-kaufmann.ch>]

  *) mod_rewrite: Extend the [CO] (cookie) flag of RewriteRule to accept a
     SameSite attribute. [Eric Covener]

  *) mod_proxy: Add proxy check_trans hook.  This allows proxy 
     modules to decline request handling at early stage.

  *) mod_proxy_wstunnel: Decline requests without an Upgrade
     header so ws/wss can be enabled overlapping with later
     http/https.

  *) mod_http2: Log requests and sent the configured error response in case of
     early detected errors like too many or too long headers.
     [Ruediger Pluem, Stefan Eissing]

  *) mod_md: Lowered the required minimal libcurl version from 7.50 to 7.29
     as proposed by <alexander.gerasimov codeit.pro>. [Stefan Eissing]

  *) mod_ssl: Fix request body buffering with PHA in TLSv1.3.  [Joe Orton]

  *) mod_proxy_uwsgi: Fix a crash when sending environment variables with no
     value. PR 64598 [Ruediger Pluem]

  *) mod_proxy: Recognize parameters from ProxyPassMatch workers with dollar
     substitution, such that they apply to the backend connection.  Note that
     connection reuse is disabled by default to avoid compatibility issues.
     [Takashi Sato, Jan Kaluza, Eric Covener, Yann Ylavic, Jean-Frederic Clere]

Changes with Apache 2.4.46

  *) SECURITY: CVE-2020-11984 (cve.mitre.org)
     mod_proxy_uwsgi: Malicious request may result in information disclosure
     or RCE of existing file on the server running under a malicious process
     environment. [Yann Ylavic]

  *) SECURITY: CVE-2020-11993 (cve.mitre.org)
     mod_http2: when throttling connection requests, log statements
     where possibly made that result in concurrent, unsafe use of
     a memory pool. [Stefan Eissing]

  *) SECURITY: CVE-2020-9490 (cve.mitre.org)
     mod_http2: a specially crafted value for the 'Cache-Digest' header
     request would result in a crash when the server actually tries
     to HTTP/2 PUSH a resource afterwards. [Stefan Eissing]

  *) mod_proxy_fcgi: Fix missing APLOGNO macro argument
     [Eric Covener, Christophe Jaillet]

Changes with Apache 2.4.45

  *) mod_http2: remove support for abandoned http-wg draft
     <https://datatracker.ietf.org/doc/draft-kazuho-h2-cache-digest/>.
     [Stefan Eissing]

Changes with Apache 2.4.44

  *) mod_proxy_uwsgi: Error out on HTTP header larger than 16K (hard
     protocol limit).  [Yann Ylavic]

  *) mod_http2: 
     Fixes <https://github.com/icing/mod_h2/issues/200>: 
     "LimitRequestFields 0" now disables the limit, as documented.
     Fixes <https://github.com/icing/mod_h2/issues/201>: 
     Do not count repeated headers with same name against the field
     count limit. The are merged internally, as if sent in a single HTTP/1 line.
     [Stefan Eissing]

  *) mod_http2: Avoid segfaults in case of handling certain responses for
     already aborted connections.  [Stefan Eissing, Ruediger Pluem]

  *) mod_http2: The module now handles master/secondary connections and has marked
     methods according to use. [Stefan Eissing]

  *) core: Drop an invalid Last-Modified header value coming
     from a FCGI/CGI script instead of replacing it with Unix epoch.
     [Yann Ylavic, Luca Toscano]

  *) Add support for strict content-length parsing through addition of
     ap_parse_strict_length() [Yann Ylavic]

  *) mod_proxy_fcgi: ProxyFCGISetEnvIf unsets variables when expression
     evaluates to false.  PR64365. [Michael König <mail ikoenig.net>]

  *) mod_proxy_http: flush spooled request body in one go to avoid
     leaking (or long lived) temporary file. PR 64452. [Yann Ylavic]

  *) mod_ssl: Fix a race condition and possible crash when using a proxy client
     certificate (SSLProxyMachineCertificateFile).
     [Armin Abfalterer <a.abfalterer gmail.com>]

  *) mod_ssl: Fix memory leak in stapling code. PR63687. [Stefan Eissing]

  *) mod_http2: Fixed regression that no longer set H2_STREAM_ID and H2_STREAM_TAG.
     PR64330 [Stefan Eissing]

  *) mod_http2: Fixed regression that caused connections to close when mod_reqtimeout
     was configured with a handshake timeout. Fixes gitub issue #196.
     [Stefan Eissing]

  *) mod_proxy_http2: the "ping" proxy parameter
     (see <https://httpd.apache.org/docs/2.4/mod/mod_proxy.html>) is now used
     when checking the liveliness of a new or reused h2 connection to the backend.
     With short durations, this makes load-balancing more responsive. The module
     will hold back requests until ping conditions are met, using features of the
     HTTP/2 protocol alone. [Ruediger Pluem, Stefan Eissing]

  *) core: httpd is no longer linked against -lsystemd if mod_systemd
     is enabled (and built as a DSO).  [Rainer Jung]

  *) mod_proxy_http2: respect ProxyTimeout settings on backend connections
     while waiting on incoming data. [Ruediger Pluem, Stefan Eissing]

Changes with Apache 2.4.43

  *) mod_ssl: Fix memory leak of OCSP stapling response. [Yann Ylavic]

Changes with Apache 2.4.42

  *) SECURITY: CVE-2020-1934 (cve.mitre.org)
     mod_proxy_ftp: Use of uninitialized value with malicious backend FTP
     server. [Eric Covener]

  *) SECURITY: CVE-2020-1927 (cve.mitre.org)
     rewrite, core: Set PCRE_DOTALL flag by default to avoid unpredictable
     matches and substitutions with encoded line break characters.
     The fix for CVE-2019-10098 was not effective.  [Ruediger Pluem]

  *) mod_proxy_http: Fix the forwarding of requests with content body when a
     balancer member is unavailable; the retry on the next member was issued
     with an empty body (regression introduced in 2.4.41). PR63891. 
     [Yann Ylavic]

  *) core: Use a temporary file when writing the pid file, avoiding
     startup failure if an empty pidfile is left over from a
     previous crashed or aborted invocation of httpd.  PR 63140.
     [Nicolas Carrier <carrier.nicolas0 gmail.com>, Joe Orton]

  *) mod_http2: Fixes issue where mod_unique_id would generate non-unique request
     identifier under load, see <https://github.com/icing/mod_h2/issues/195>.
     [Michael Kaufmann, Stefan Eissing]

  *) mod_proxy_hcheck: Allow healthcheck expressions to use %{Content-Type}.
     PR64140. [Renier Velazco <renier.velazco upr.edu>]

  *) mod_authz_groupfile: Drop AH01666 from loglevel "error" to "info".
     PR64172.

  *) mod_usertrack: Add CookieSameSite, CookieHTTPOnly, and CookieSecure 
     to allow customization of the usertrack cookie. PR64077.
     [Prashant Keshvani <prashant2400 gmail.com>, Eric Covener]

  *) mod_proxy_ajp: Add "secret" parameter to proxy workers to implement legacy
     AJP13 authentication.  PR 53098. [Dmitry A. Bakshaev <dab1818 gmail com>]

  *) mpm_event: avoid possible KeepAliveTimeout off by -100 ms.
     [Eric Covener, Yann Ylavic]

  *) Add a config layout for OpenWRT. [Graham Leggett]

  *) Add support for cross compiling to apxs. If apxs is being executed from
     somewhere other than its target location, add that prefix to includes and
     library directories. Without this, apxs would fail to find config_vars.mk
     and exit. [Graham Leggett]

  *) mod_ssl: Disable client verification on ACME ALPN challenges. Fixes github
     issue mod_md#172 (https://github.com/icing/mod_md/issues/172).
     [Michael Kaufmann <mail michael-kaufmann.ch>, Stefan Eissing]

  *) mod_ssl: use OPENSSL_init_ssl() to initialise OpenSSL on versions 1.1+.
     [Graham Leggett]

  *) mod_ssl: Support use of private keys and certificates from an
     OpenSSL ENGINE via PKCS#11 URIs in SSLCertificateFile/KeyFile.
     [Anderson Sasaki <ansasaki redhat.com>, Joe Orton]

  *) mod_md:
     - Prefer MDContactEmail directive to ServerAdmin for registration. New directive
       thanks to Timothe Litt (@tlhackque).
     - protocol check for pre-configured "tls-alpn-01" challenge has been improved. It will now
       check all matching virtual hosts for protocol support. Thanks to @mkauf.
     - Corrected a check when OCSP stapling was configured for hosts
       where the responsible MDomain is not clear, by Michal Karm Babacek (@Karm).
     - Softening the restrictions where mod_md configuration directives may appear. This should
       allow for use in <If> and <Macro> sections. If all possible variations lead to the configuration
       you wanted in the first place, is another matter.
     [Michael Kaufmann <mail michael-kaufmann.ch>, Timothe Litt (@tlhackque),
      Michal Karm Babacek (@Karm), Stefan Eissing (@icing)] 

  *) test: Added continuous testing with Travis CI.
     This tests various scenarios on Ubuntu with the full test suite.
     Architectures tested: amd64, s390x, ppc64le, arm64
     The tests pass successfully.
     [Luca Toscano, Joe Orton, Mike Rumph, and others]

  *) core: Be stricter in parsing of Transfer-Encoding headers.
     [ZeddYu <zeddyu.lu gmail.com>, Eric Covener]

  *) mod_ssl: negotiate the TLS protocol version per name based vhost
     configuration, when linked with OpenSSL-1.1.1 or later. The base vhost's
     SSLProtocol (from the first vhost declared on the IP:port) is now only
     relevant if no SSLProtocol is declared for the vhost or globally,
     otherwise the vhost or global value apply.  [Yann Ylavic]

  *) mod_cgi, mod_cgid: Fix a memory leak in some error cases with large script
     output.  PR 64096.  [Joe Orton]

  *) config: Speed up graceful restarts by using pre-hashed command table. PR 64066.
     [Giovanni Bechis <giovanni paclan.it>, Jim Jagielski]

  *) mod_systemd: New module providing integration with systemd.  [Jan Kaluza]

  *) mod_lua: Add r:headers_in_table, r:headers_out_table, r:err_headers_out_table,
     r:notes_table, r:subprocess_env_table as read-only native table alternatives
     that can be iterated over. [Eric Covener]

  *) mod_http2: Fixed rare cases where a h2 worker could deadlock the main connection. 
     [Yann Ylavic, Stefan Eissing]

  *) mod_lua: Accept nil assignments to the exposed tables (r.subprocess_env, 
     r.headers_out, etc) to remove the key from the table. PR63971. 
     [Eric Covener]

  *) mod_http2: Fixed interaction with mod_reqtimeout. A loaded mod_http2 was disabling the
     ssl handshake timeouts. Also, fixed a mistake of the last version that made `H2Direct` 
     always `on`, regardless of configuration. Found and reported by
     <Armin.Abfalterer@united-security-providers.ch> and
     <Marcial.Rion@united-security-providers.ch>. [Stefan Eissing] 

  *) mod_http2: Multiple field length violations in the same request no longer cause
     several log entries to be written. [@mkauf]

  *) mod_ssl: OCSP does not apply to proxy mode.  PR 63679.
     [Lubos Uhliarik <luhliari redhat.com>, Yann Ylavic]

  *) mod_proxy_html, mod_xml2enc: Fix build issues with macOS due to r1864469
     [Jim Jagielski]
 
  *) mod_authn_socache: Increase the maximum length of strings that can be cached by
     the module from 100 to 256.  PR 62149 [<thorsten.meinl knime.com>]

  *) mod_proxy: Fix crash by resolving pool concurrency problems. PR 63503
     [Ruediger Pluem, Eric Covener]

  *) core: On Windows, fix a start-up crash if <IfFile ...> is used with a path that is not
     valid (For example, testing for a file on a flash drive that is not mounted)
     [Christophe Jaillet]

  *) mod_deflate, mod_brotli: honor "Accept-Encoding: foo;q=0" as per RFC 7231; which
     means 'foo' is "not acceptable".  PR 58158 [Chistophe Jaillet]

  *) mod_md v2.2.3: 
     - Configuring MDCAChallenges replaces any previous existing challenge configuration. It
       had been additive before which was not the intended behaviour. [@mkauf]
     - Fixing order of ACME challenges used when nothing else configured. Code now behaves as
       documented for `MDCAChallenges`. Fixes #156. Thanks again to @mkauf for finding this.
     - Fixing a potential, low memory null pointer dereference [thanks to @uhliarik].
     - Fixing an incompatibility with a change in libcurl v7.66.0 that added unwanted
       "transfer-encoding" to POST requests. This failed in direct communication with
       Let's Encrypt boulder server. Thanks to @mkauf for finding and fixing. [Stefan Eissing]

  *) mod_md: Adding the several new features.
     The module offers an implementation of OCSP Stapling that can replace fully or
     for a limited set of domains the existing one from mod_ssl. OCSP handling
     is part of mod_md's monitoring and message notifications. If can be used
     for sites that do not have ACME certificates.
     The url for a CTLog Monitor can be configured. It is used in the server-status
     to link to the external status page of a certificate.
     The MDMessageCmd is called with argument "installed" when a new certificate
     has been activated on server restart/reload. This allows for processing of
     the new certificate, for example to applications that require it in different
     locations or formats.
     [Stefan Eissing]

  *) mod_proxy_balancer: Fix case-sensitive referer check related to CSRF/XSS 
     protection. PR 63688. [Armin Abfalterer <a.abfalterer gmail.com>]

Changes with Apache 2.4.41

  *) SECURITY: CVE-2019-10097 (cve.mitre.org)
     mod_remoteip: Fix stack buffer overflow and NULL pointer deference
     when reading the PROXY protocol header.  [Joe Orton,
     Daniel McCarney <cpu letsencrypt.org>]

  *) SECURITY: CVE-2019-9517 (cve.mitre.org)
     mod_http2: a malicious client could perform a DoS attack by flooding
        a connection with requests and basically never reading responses
        on the TCP connection. Depending on h2 worker dimensioning, it was
        possible to block those with relatively few connections. [Stefan Eissing]

  *) SECURITY: CVE-2019-10098 (cve.mitre.org)
     rewrite, core: Set PCRE_DOTALL flag by default to avoid unpredictable
     matches and substitutions with encoded line break characters.
     [Yann Ylavic]

  *) SECURITY: CVE-2019-10092 (cve.mitre.org)
     Remove HTML-escaped URLs from canned error responses to prevent misleading
     text/links being displayed via crafted links. [Eric Covener]

  *) SECURITY: CVE-2019-10082 (cve.mitre.org)
     mod_http2: Using fuzzed network input, the http/2 session
     handling could be made to read memory after being freed,
     during connection shutdown. [Stefan Eissing]

  *) SECURITY: CVE-2019-10081 (cve.mitre.org)
     mod_http2: HTTP/2 very early pushes, for example configured with "H2PushResource",
        could lead to an overwrite of memory in the pushing request's pool,
        leading to crashes. The memory copied is that of the configured push
        link header values, not data supplied by the client. [Stefan Eissing]

  *) mod_proxy_balancer: Improve balancer-manager protection against 
     XSS/XSRF attacks from trusted users.  [Joe Orton,
     Niels Heinen <heinenn google.com>]

  *) mod_session: Introduce SessionExpiryUpdateInterval which allows to
     configure the session/cookie expiry's update interval. PR 57300.
     [Paul Spangler <paul.spangler ni.com>]

  *) modules/filters: Fix broken compilation when using old GCC (<4.2.x).
     PR 63633.  [Rainer Jung, Joe Orton]

  *) mod_ssl: Fix startup failure in 2.4.40 with SSLCertificateChainFile
     configured for a domain managed by mod_md.  [Stefan Eissing]

Changes with Apache 2.4.40

  *) core, mod_rewrite: Set PCRE_DOTALL by default. Revert via 
     RegexDefaultOptions -DOTALL [Yann Ylavic]

  *) core: Remove request details from built-in error documents [Eric Covener]

  *) mod_http2: core setting "LimitRequestFieldSize" is not additionally checked on
     merged header fields, just as HTTP/1.1 does. [Stefan Eissing, Michael Kaufmann]

  *) mod_http2: fixed a bug that prevented proper stream cleanup when connection
     throttling was in place. Stream resets by clients on streams initiated by them
     are counted as possible trigger for throttling. [Stefan Eissing]

  *) mod_http2/mpm_event: Fixes the behaviour when a HTTP/2 connection has nothing
     more to write with streams ongoing (flow control block). The timeout waiting
     for the client to send WINODW_UPDATE was incorrectly KeepAliveTimeout and not
     Timeout as it should be. Fixes PR 63534. [Yann Ylavic, Stefan Eissing]

  *) mod_proxy_balancer: Load balancer required byrequests when bytraffic chosen.
     PR 62372. [Jim Jagielski]

  *) mod_proxy_hcheck: Create the configuration for mod_proxy_hcheck
     when used in BalancerMember. PR 60757. [Jean-Frederic Clere]

  *) mod_proxy_hcheck: Mute extremely frequent debug message. [Yann Ylavic]

  *) mod_ssl/mod_md: reversing dependency by letting mod_ssl offer hooks for
     adding certificates and keys to a virtual host. An additional hook allows
     answering special TLS connections as used in ACME challenges.
     Adding 2 new hooks for init/get of OCSP stapling status information when
     other modules want to provide those. Falls back to own implementation with
     same behaviour as before.
     [Stefan Eissing]
  
  *) mod_md: new features
     - protocol
       - supports the ACMEv2 protocol. It is the default and will be used on the next
         certificate renewal, unless another "MDCertificateAuthority" is configured
       - ACMEv2 endpoints use the GET via empty POST way of accessing resources, see
         announcement by Let's Encrypt:       
         https://community.letsencrypt.org/t/acme-v2-scheduled-deprecation-of-unauthenticated-resource-gets/74380
     - challenges
       - new challenge method 'tls-alpn-01' implemented
       - challenge type 'tls-sni-01' has been removed as CAs do not offer this any longer
       - supports command configuration to setup/teardown 'dns-01' challenges
       - supports wildcard certificates when dns challenges are configured
     - status information and monitoring
       - a domain exposes its status at https://<domain>/.httpd/certificate-status
       - Managed Domains are now in Apache's 'server-status' page
       - A new handler 'md-status' exposes verbose status information in JSON format
     - new directives
       - "MDCertificateFile" and "MDCertificateKeyFile" to configure a
         Managed Domain that uses static files. Auto-renewal is turned off for those.
       - "MDMessageCmd" that is invoked on several events: 'renewed', 'expiring' and
         'errored'.
       - "MDWarnWindow" directive to configure when expiration warnings shall be issued.
     [Stefan Eissing]

  *) mod_mime_magic: Fix possible corruption of returned strings.
     [Christophe Jaillet]

  *) Default "conf/magic": Fix pattern for "audio/x-wav" for WAV files,
     remove "audio/unknown" pattern for other RIFF files.
     [Àngel Ollé Blázquez <aollebla redhat.com>]

  *) mod_proxy_http2: fixing a potential NULL pointer use in logging.
     [Christophe Jaillet, Dr Silvio Cesare InfoSect]

  *) mod_dav: Reduce the amount of memory needed when doing PROPFIND's on large
     collections by improving the memory management. [Joe Orton, Ruediger Pluem]

  *) mod_proxy_http2: adding support for handling trailers in both directions.
     PR 63502. [Stefan Eissing]

  *) mod_proxy_http: forward 100-continue, and minimize race conditions when
     reusing backend connections. PR 60330. [Yann Ylavic, Jean-Frederic Clere]

  *) mod_proxy_balancer: Fix some HTML syntax issues.  [Christophe Jaillet]
[--snip--]
