ChangeLog

Changes in version 0.4.2.1-alpha - 2019-09-??
  This is the first alpha release in the 0.4.2.x series. It adds new
  defenses for denial-of-service attacks against onion services. It also
  includes numerous kinds of bugfixes and refactoring to help improve
  Tor's stability and ease of development.

  o Major features (onion service v3, denial of service):
    - Add onion service introduction denial of service defenses. Intro
      points can now rate-limit client introduction requests, using
      parameters that can be sent by the service within the
      ESTABLISH_INTRO cell. If the cell extension for this is not used,
      the intro point will honor the consensus parameters. Closes
      ticket 30924.

  o Major bugfixes (circuit build, guard):
    - When considering upgrading circuits from "waiting for guard" to
      "open", always ignore circuits that are marked for close.
      Previously we could end up in the situation where a subsystem is
      notified of a circuit opening, but the circuit is still marked for
      close, leading to undesirable behavior. Fixes bug 30871; bugfix
      on 0.3.0.1-alpha.

  o Major bugfixes (crash, Linux, Android):
    - Tolerate systems (including some Android installations) where
      madvise and MADV_DONTDUMP are available at build-time, but not at
      run time. Previously, these systems would notice a failed syscall
      and abort. Fixes bug 31570; bugfix on 0.4.1.1-alpha.
    - Tolerate systems (including some Linux installations) where
      madvise and/or MADV_DONTFORK are available at build-time, but not
      at run time. Previously, these systems would notice a failed
      syscall and abort. Fixes bug 31696; bugfix on 0.4.1.1-alpha.

  o Minor features (best practices tracker):
    - Our best-practices tracker now integrates with our include-checker
      tool to keep track of how many layering violations we have not yet
      fixed. We hope to reduce this number over time to improve Tor's
      modularity. Closes ticket 31176.
    - Add a TOR_PRACTRACKER_OPTIONS variable for passing arguments to
      practracker from the environment. We may want this for continuous
      integration. Closes ticket 31309.
    - Give a warning rather than an error when a practracker exception
      is violated by a small amount, add a --list-overbroad option to
      practracker that lists exceptions that are stricter than they need
      to be, and provide an environment variable for disabling
      practracker. Closes ticket 30752.
    - Our best-practices tracker now looks at headers as well as C
      files. Closes ticket 31175.

  o Minor features (build system):
    - Add --disable-manpage and --disable-html-manual options to
      configure script. This will enable shortening build times by not
      building documentation. Resolves issue 19381.

  o Minor features (compilation):
    - Log a more useful error message when we are compiling and one of
      the compile-time hardening options we have selected can be linked
      but not executed. Closes ticket 27530.

  o Minor features (configuration):
    - The configuration code has been extended to allow splitting
      configuration data across multiple objects. Previously, all
      configuration data needed to be kept in a single object, which
      tended to become bloated. Closes ticket 31240.

  o Minor features (continuous integration):
    - When running CI builds on Travis, put some random data in
      ~/.torrc, to make sure no tests are reading the Tor configuration
      file from its default location. Resolves issue 30102.

  o Minor features (debugging):
    - Log a nonfatal assertion failure if we encounter a configuration
      line whose command is "CLEAR" but which has a nonempty value. This
      should be impossible, according to the rules of our configuration
      line parsing. Closes ticket 31529.

  o Minor features (git hooks):
    - Our pre-commit git hook now checks for a special file before
      running practracker, so that practracker only runs on branches
      that are based on master. Since the pre-push hook calls the pre-
      commit hook, practracker will also only run before pushes of
      branches based on master. Closes ticket 30979.

  o Minor features (git scripts):
    - Add a "--" command-line argument, to separate git-push-all.sh
      script arguments from arguments that are passed through to git
      push. Closes ticket 31314.
    - Add a -r <remote-name> argument to git-push-all.sh, so the script
      can push test branches to a personal remote. Closes ticket 31314.
    - Add a -t <test-branch-prefix> argument to git-merge-forward.sh and
      git-push-all.sh, which makes these scripts create, merge forward,
      and push test branches. Closes ticket 31314.
    - Add a -u argument to git-merge-forward.sh, so that the script can
      re-use existing test branches after a merge failure and fix.
      Closes ticket 31314.
    - Add a TOR_GIT_PUSH env var, which sets the default git push
      command and arguments for git-push-all.sh. Closes ticket 31314.
    - Add a TOR_PUSH_DELAY variable to git-push-all.sh, which makes the
      script push master and maint branches with a delay between each
      branch. These delays trigger the CI jobs in a set order, which
      should show the most likely failures first. Also make pushes
      atomic by default, and make the script pass any command-line
      arguments to git push. Closes ticket 29879.
    - Call the shellcheck script from the pre-commit hook. Closes
      ticket 30967.
    - Skip pushing test branches that are the same as a remote
      maint/release/master branch in git-push-all.sh by default. Add a
      -s argument, so git-push-all.sh can push all test branches. Closes
      ticket 31314.

  o Minor features (IPv6, logging):
    - Log IPv6 addresses as well as IPv4 addresses when describing
      routerinfos, routerstatuses, and nodes. Closes ticket 21003.

  o Minor features (onion service v3):
    - Do not allow single hop clients to fetch or post an HS descriptor
      from an HSDir. Closes ticket 24964.

  o Minor features (onion service):
    - Disallow single-hop clients at the introduction point. We've
      removed Tor2web support a while back and single-hop rendezvous
      attempts are blocked at the relays. This change should remove load
      off the network from spammy clients. Close ticket 24963.

  o Minor features (stem tests):
    - Change "make test-stem" so it only runs the stem tests that use
      tor. This change makes test-stem faster and more reliable. Closes
      ticket 31554.

  o Minor features (testing):
    - Add a script to invoke "tor --dump-config" and "tor
      --verify-config" with various configuration options, and see
      whether tor's resulting configuration or error messages are what
      we expect. Use it for integration testing of our +Option and
      /Option flags. Closes ticket 31637.
    - Improve test coverage for our existing configuration parsing and
      management API. Closes ticket 30893.
    - Add integration tests to make sure that practracker gives the
      outputs we expect. Closes ticket 31477.
    - The practracker self-tests are now run as part of the Tor test
      suite. Closes ticket 31304.

  o Minor features (token bucket):
    - Implement a generic token bucket that uses a single counter, for
      use in anti-DoS onion service work. Closes ticket 30687.

  o Minor bugfixes (best practices tracker):
    - Fix a few issues in the best-practices script, including tests,
      tab tolerance, error reporting, and directory-exclusion logic.
      Fixes bug 29746; bugfix on 0.4.1.1-alpha.
    - When running check-best-practices, only consider files in the src
      subdirectory. Previously we had recursively considered all
      subdirectories, which made us get confused by the temporary
      directories made by "make distcheck". Fixes bug 31578; bugfix
      on 0.4.1.1-alpha.

  o Minor bugfixes (build system):
    - Do not include the deprecated <sys/sysctl.h> on Linux or Windows
      systems. Fixes bug 31673; bugfix on 0.2.5.4-alpha.

  o Minor bugfixes (chutney, makefiles, documentation):
    - "make test-network-all" now shows the warnings from each test-
      network.sh run on the console, so developers see new warnings
      early. We've also improved the documentation for this feature, and
      renamed a Makefile variable so the code is self-documenting. Fixes
      bug 30455; bugfix on 0.3.0.4-rc.

  o Minor bugfixes (compilation):
    - Add more stub functions to fix compilation on Android with link-
      time optimization when --disable-module-dirauth is used.
      Previously, these compilation settings would make the compiler
      look for functions that didn't exist. Fixes bug 31552; bugfix
      on 0.4.1.1-alpha.

  o Minor bugfixes (configuration):
    - Invalid floating-point values in the configuration file are now
      treated as errors in the configuration. Previously, they were
      ignored and treated as zero. Fixes bug 31475; bugfix on 0.0.1.

  o Minor bugfixes (coverity):
    - Add an assertion when parsing a BEGIN cell so that coverity can be
      sure that we are not about to dereference a NULL address. Fixes
      bug 31026; bugfix on 0.2.4.7-alpha. This is CID 1447296.
    - In our siphash implementation, when building for coverity, use
      memcpy in place of a switch statement, so that coverity can tell
      we are not accessing out-of-bounds memory. Fixes bug 31025; bugfix
      on 0.2.8.1-alpha. This is tracked as CID 1447293 and 1447295.
    - Fix several coverity warnings from our unit tests. Fixes bug
      31030; bugfix on 0.2.4.1-alpha, 0.3.2.1-alpha, and 0.4.0.1-alpha.

  o Minor bugfixes (developer tooling):
    - Only log git script changes in the post-merge script when the
      merge was to the master branch. Fixes bug 31040; bugfix
      on 0.4.1.1-alpha.

  o Minor bugfixes (directory authorities):
    - Return a distinct status when formatting annotations fails. Fixes
      bug 30780; bugfix on 0.2.0.8-alpha.

  o Minor bugfixes (error handling):
    - On abort, try harder to flush the output buffers of log messages.
      On some platforms (macOS), log messages could be discarded when
      the process terminates. Fixes bug 31571; bugfix on 0.3.5.1-alpha.
    - Report the tor version whenever an assertion fails. Previously, we
      only reported the Tor version on some crashes, and some non-fatal
      assertions. Fixes bug 31571; bugfix on 0.3.5.1-alpha.
    - When tor aborts due to an error, close log file descriptors before
      aborting. Closing the logs makes some OSes flush log file buffers,
      rather than deleting buffered log lines. Fixes bug 31594; bugfix
      on 0.2.5.2-alpha.

  o Minor bugfixes (git hooks):
    - Remove a duplicate call to practracker from the pre-push hook. The
      pre-push hook already calls the pre-commit hook, which calls
      practracker. Fixes bug 31462; bugfix on 0.4.1.1-alpha.

  o Minor bugfixes (git scripts):
    - Stop hard-coding the bash path in the git scripts. Some OSes don't
      have bash in /usr/bin, others have an ancient bash at this path.
      Fixes bug 30840; bugfix on 0.4.0.1-alpha.
    - Stop hard-coding the tor master branch name and worktree path in
      the git scripts. Fixes bug 30841; bugfix on 0.4.0.1-alpha.
    - Allow git-push-all.sh to be run from any directory. Previously,
      the script only worked if run from an upstream worktree directory.
      Closes ticket 31678.

  o Minor bugfixes (guards):
    - When tor is missing descriptors for some primary entry guards,
      make the log message less alarming. It's normal for descriptors to
      expire, as long as tor fetches new ones soon after. Fixes bug
      31657; bugfix on 0.3.3.1-alpha.

  o Minor bugfixes (ipv6):
    - Check for private IPv6 addresses alongside their IPv4 equivalents
      when authorities check descriptors. Previously, we only checked
      for private IPv4 addresses. Fixes bug 31088; bugfix on
      0.2.3.21-rc. Patch by Neel Chauhan.
    - When parsing microdescriptors, we should check the IPv6 exit
      policy alongside IPv4. Previously, we checked both exit policies
      for only router info structures, while microdescriptors were
      IPv4-only. Fixes bug 27284; bugfix on 0.2.3.1-alpha. Patch by
      Neel Chauhan.

  o Minor bugfixes (logging):
    - Change log level of message "Hash of session info was not as
      expected" to LOG_PROTOCOL_WARN. Fixes bug 12399; bugfix
      on 0.1.1.10-alpha.
    - Fix a code issue that would have broken our parsing of log domains
      as soon as we had 33 of them. Fortunately, we still only have 29.
      Fixes bug 31451; bugfix on 0.4.1.4-rc.

  o Minor bugfixes (memory management):
    - Stop leaking a small amount of memory in nt_service_install(), in
      unreachable code. Fixes bug 30799; bugfix on 0.2.0.7-alpha. Patch
      by Xiaoyin Liu.

  o Minor bugfixes (networking, IP addresses):
    - When parsing addresses via Tor's internal DNS lookup API, reject
      IPv4 addresses in square brackets, and accept IPv6 addresses in
      square brackets. This change completes the work started in 23082,
      making address parsing consistent between tor's internal DNS
      lookup and address parsing APIs. Fixes bug 30721; bugfix
      on 0.2.1.5-alpha.
    - When parsing addresses via Tor's internal address:port parsing and
      DNS lookup APIs, require IPv6 addresses with ports to have square
      brackets. But allow IPv6 addresses without ports, whether or not
      they have square brackets. Fixes bug 30721; bugfix
      on 0.2.1.5-alpha.

  o Minor bugfixes (onion service v3):
    - When purging the client descriptor cache, close any introduction
      point circuits associated with purged cache entries. This avoids
      picking those circuits later when connecting to the same
      introduction points. Fixes bug 30921; bugfix on 0.3.2.1-alpha.

  o Minor bugfixes (onion services):
    - In the hs_ident_circuit_t data structure, remove the unused field
      circuit_type and the respective argument in hs_ident_circuit_new().
      This field was set by clients (for introduction) and services (for
      introduction and rendezvous) but was never used afterwards. Fixes
      bug 31490; bugfix on 0.3.2.1-alpha. Patch by Neel Chauhan.

  o Minor bugfixes (operator tools):
    - Make tor-print-ed-signing-cert(1) print certificate expiration
      date in RFC 1123 and UNIX timestamp formats, to make output
      machine readable. Fixes bug 31012; bugfix on 0.3.5.1-alpha.

  o Minor bugfixes (rust):
    - Correctly exclude a redundant rust build job in Travis. Fixes bug
      31463; bugfix on 0.3.5.4-alpha.
    - Raise the minimum rustc version to 1.31.0, as checked by configure
      and CI. Fixes bug 31442; bugfix on 0.3.5.4-alpha.

  o Minor bugfixes (sendme, code structure):
    - Rename the trunnel SENDME file definition from sendme.trunnel to
      sendme_cell.trunnel to avoid having twice sendme.{c|h} in the
      repository. Fixes bug 30769; bugfix on 0.4.1.1-alpha.

  o Minor bugfixes (statistics):
    - Stop removing the ed25519 signature if the extra info file is too
      big. If the signature data was removed, but the keyword was kept,
      this could result in an unparseable extra info file. Fixes bug
      30958; bugfix on 0.2.7.2-alpha.

  o Minor bugfixes (subsystems):
    - Make the subsystem init order match the subsystem module
      dependencies. Call windows process security APIs as early as
      possible. Initialize logging before network and time, so that
      network and time can use logging. Fixes bug 31615; bugfix
      on 0.4.0.1-alpha.

  o Minor bugfixes (testing):
    - Teach the util/socketpair_ersatz test to work correctly when we
      have no network stack configured. Fixes bug 30804; bugfix
      on 0.2.5.1-alpha.

  o Minor bugfixes (v2 single onion services):
    - Always retry v2 single onion service intro and rend circuits with
      a 3-hop path. Previously, v2 single onion services used a 3-hop
      path when rendezvous circuits were retried after a remote or
      delayed failure, but a 1-hop path for immediate retries. Fixes bug
      23818; bugfix on 0.2.9.3-alpha.

  o Minor bugfixes (v3 single onion services):
    - Always retry v3 single onion service intro and rend circuits with
      a 3-hop path. Previously, v3 single onion services used a 3-hop
      path when rend circuits were retried after a remote or delayed
      failure, but a 1-hop path for immediate retries. Fixes bug 23818;
      bugfix on 0.3.2.1-alpha.
    - Make v3 single onion services fall back to a 3-hop intro, when all
      intro points are unreachable via a 1-hop path. Previously, v3
      single onion services failed when all intro nodes were unreachable
      via a 1-hop path. Fixes bug 23507; bugfix on 0.3.2.1-alpha.

  o Documentation:
    - Improve documentation in circuit padding subsystem. Patch by
      Tobias Pulls. Closes ticket 31113.
    - Include an example usage for IPv6 ORPort in our sample torrc.
      Closes ticket 31320; patch from Ali Raheem.
    - Use RFC 2397 data URL scheme to embed an image into tor-exit-
      notice.html so that operators no longer have to host it
      themselves. Closes ticket 31089.

  o Removed features:
    - No longer include recommended package digests in votes as detailed
      in proposal 301. The RecommendedPackages torrc option is
      deprecated and will no longer have any effect. "package" lines
      will still be considered when computing consensuses for consensus
      methods that include them. (This change has no effect on the list
      of recommended Tor versions, which is still in use.) Closes
      ticket 29738.
    - Remove torctl.in from contrib/dist directory. Resolves
      ticket 30550.

  o Testing:
    - Run shellcheck for all non-third-party shell scripts that are
      shipped with Tor. Closes ticket 29533.
    - When checking shell scripts, ignore any user-created directories.
      Closes ticket 30967.

  o Code simplification and refactoring (config handling):
    - Extract our variable manipulation code from confparse.c to a new
      lower-level typedvar.h module. Closes ticket 30864.
    - Lower another layer of object management from confparse.c to a
      more general tool. Now typed structure members are accessible via
      an abstract type. Implements ticket 30914.
    - Move our backend logic for working with configuration and state
      files into a lower-level library, since it no longer depends on
      any tor-specific functionality. Closes ticket 31626.
    - Numerous simplifications in configuration-handling logic: remove
      duplicated macro definitions, replace magical names with flags,
      and refactor "TestingTorNetwork" to use the same default-option
      logic as the rest of Tor. Closes ticket 30935.
    - Replace our ad-hoc set of flags for configuration variables and
      configuration variable types with fine-grained orthogonal flags
      corresponding to the actual behavior we want. Closes ticket 31625.

  o Code simplification and refactoring (misc):
    - Eliminate some uses of lower-level control reply abstractions,
      primarily in the onion_helper functions. Closes ticket 30889.
    - Rework bootstrap tracking to use the new publish-subscribe
      subsystem. Closes ticket 29976.
    - Rewrite format_node_description() and router_get_verbose_nickname()
      to use strlcpy() and strlcat(). The previous implementation used
      memcpy() and pointer arithmetic, which was error-prone. Closes
      ticket 31545. This is CID 1452819.
    - Split extrainfo_dump_to_string() into smaller functions. Closes
      ticket 30956.
    - Use the ptrdiff_t type consistently for expressing variable
      offsets and pointer differences. Previously we incorrectly (but
      harmlessly) used int and sometimes off_t for these cases. Closes
      ticket 31532.
    - Use the subsystems mechanism to manage the main event loop code.
      Closes ticket 30806.
    - Various simplifications and minor improvements to the circuit
      padding machines. Patch by Tobias Pulls. Closes tickets 31112
      and 31098.

  o Documentation (hard-coded directories):
    - Improve the documentation for the DirAuthority and FallbackDir
      torrc options. Closes ticket 30955.

  o Documentation (tor.1 man page):
    - Fix typo in tor.1 man page: the option is "--help", not "-help".
      Fixes bug 31008; bugfix on 0.2.2.9-alpha.


Changes in version 0.4.1.5 - 2019-08-20
  This is the first stable release in the 0.4.1.x series. This series
  adds experimental circuit-level padding, authenticated SENDME cells to
  defend against certain attacks, and several performance improvements
  to save on CPU consumption. It fixes bugs in bootstrapping and v3
  onion services. It also includes numerous smaller features and
  bugfixes on earlier versions.

  Per our support policy, we will support the 0.4.1.x series for nine
  months, or until three months after the release of a stable 0.4.2.x:
  whichever is longer. If you need longer-term support, please stick
  with 0.3.5.x, which will we plan to support until Feb 2022.

  Below are the changes since 0.4.1.4-rc. For a complete list of changes
  since 0.4.0.5, see the ReleaseNotes file.

  o Directory authority changes:
    - The directory authority "dizum" has a new IP address. Closes
      ticket 31406.

  o Minor features (circuit padding logging):
    - Demote noisy client-side warn logs about circuit padding to
      protocol warnings. Add additional log messages and circuit ID
      fields to help with bug 30992 and any other future issues.

  o Minor bugfixes (circuit padding negotiation):
    - Bump the circuit padding protocol version to explicitly signify
      that the HS setup machine support is finalized in 0.4.1.x-stable.
      This also means that 0.4.1.x-alpha clients will not negotiate
      padding with 0.4.1.x-stable relays, and 0.4.1.x-stable clients
      will not negotiate padding with 0.4.1.x-alpha relays (or 0.4.0.x
      relays). Fixes bug 31356; bugfix on 0.4.1.1-alpha.

  o Minor bugfixes (circuit padding):
    - Ignore non-padding cells on padding circuits. This addresses
      various warning messages from subsystems that were not expecting
      padding circuits. Fixes bug 30942; bugfix on 0.4.1.1-alpha.

  o Minor bugfixes (clock skew detection):
    - Don't believe clock skew results from NETINFO cells that appear to
      arrive before we sent the VERSIONS cells they are responding to.
      Previously, we would accept them up to 3 minutes "in the past".
      Fixes bug 31343; bugfix on 0.2.4.4-alpha.

  o Minor bugfixes (compatibility, standards compliance):
    - Fix a bug that would invoke undefined behavior on certain
      operating systems when trying to asprintf() a string exactly
      INT_MAX bytes long. We don't believe this is exploitable, but it's
      better to fix it anyway. Fixes bug 31001; bugfix on 0.2.2.11-alpha.
      Found and fixed by Tobias Stoeckmann.

  o Minor bugfixes (compilation warning):
    - Fix a compilation warning on Windows about casting a function
      pointer for GetTickCount64(). Fixes bug 31374; bugfix
      on 0.2.9.1-alpha.

  o Minor bugfixes (compilation):
    - Avoid using labs() on time_t, which can cause compilation warnings
      on 64-bit Windows builds. Fixes bug 31343; bugfix on 0.2.4.4-alpha.

  o Minor bugfixes (distribution):
    - Do not ship any temporary files found in the
      scripts/maint/practracker directory. Fixes bug 31311; bugfix
      on 0.4.1.1-alpha.

  o Testing (continuous integration):
    - In Travis, make stem log a controller trace to the console, and
      tail stem's tor log after failure. Closes ticket 30591.
    - In Travis, only run the stem tests that use a tor binary. Closes
      ticket 30694.


Changes in version 0.4.1.4-rc - 2019-07-25
  Tor 0.4.1.4-rc fixes a few bugs from previous versions of Tor, and
  updates to a new list of fallback directories. If no new bugs are
  found, the next release in the 0.4.1.x serious should be stable.

  o Major bugfixes (circuit build, guard):
    - When considering upgrading circuits from "waiting for guard" to
      "open", always ignore circuits that are marked for close. Otherwise,
      we can end up in the situation where a subsystem is notified that
      a closing circuit has just opened, leading to undesirable
      behavior. Fixes bug 30871; bugfix on 0.3.0.1-alpha.

  o Minor features (continuous integration):
    - Our Travis configuration now uses Chutney to run some network
      integration tests automatically. Closes ticket 29280.

  o Minor features (fallback directory list):
    - Replace the 157 fallbacks originally introduced in Tor 0.3.5.6-rc
      in December 2018 (of which ~122 were still functional), with a
      list of 148 fallbacks (70 new, 78 existing, 79 removed) generated
      in June 2019. Closes ticket 28795.

  o Minor bugfixes (circuit padding):
    - On relays, properly check that a padding machine is absent before
      logging a warning about it being absent. Fixes bug 30649; bugfix
      on 0.4.0.1-alpha.
    - Add two NULL checks in unreachable places to silence Coverity (CID
      144729 and 1447291) and better future-proof ourselves. Fixes bug
      31024; bugfix on 0.4.1.1-alpha.

  o Minor bugfixes (crash on exit):
    - Avoid a set of possible code paths that could try to use freed
      memory in routerlist_free() while Tor was exiting. Fixes bug
      31003; bugfix on 0.1.2.2-alpha.

  o Minor bugfixes (logging):
    - Fix a conflict between the flag used for messaging-domain log
      messages, and the LD_NO_MOCK testing flag. Fixes bug 31080; bugfix
      on 0.4.1.1-alpha.

  o Minor bugfixes (memory leaks):
    - Fix a trivial memory leak when parsing an invalid value from a
      download schedule in the configuration. Fixes bug 30894; bugfix
      on 0.3.4.1-alpha.

  o Code simplification and refactoring:
    - Remove some dead code from circpad_machine_remove_token() to fix
      some Coverity warnings (CID 1447298). Fixes bug 31027; bugfix
      on 0.4.1.1-alpha.


Changes in version 0.4.1.3-alpha - 2019-06-25
  Tor 0.4.1.3-alpha resolves numerous bugs left over from the previous
  alpha, most of them from earlier release series.

  o Major bugfixes (Onion service reachability):
    - Properly clean up the introduction point map when circuits change
      purpose from onion service circuits to pathbias, measurement, or
      other circuit types. This should fix some service-side instances
      of introduction point failure. Fixes bug 29034; bugfix
      on 0.3.2.1-alpha.

  o Minor features (geoip):
    - Update geoip and geoip6 to the June 10 2019 Maxmind GeoLite2
      Country database. Closes ticket 30852.

  o Minor features (logging):
    - Give a more useful assertion failure message if we think we have
      minherit() but we fail to make a region non-inheritable. Give a
      compile-time warning if our support for minherit() is incomplete.
      Closes ticket 30686.

  o Minor bugfixes (circuit isolation):
    - Fix a logic error that prevented the SessionGroup sub-option from
      being accepted. Fixes bug 22619; bugfix on 0.2.7.2-alpha.

  o Minor bugfixes (continuous integration):
    - Allow the test-stem job to fail in Travis, because it sometimes
      hangs. Fixes bug 30744; bugfix on 0.3.5.4-alpha.
    - Skip test_rebind on macOS in Travis, because it is unreliable on
      macOS on Travis. Fixes bug 30713; bugfix on 0.3.5.1-alpha.
    - Skip test_rebind when the TOR_SKIP_TEST_REBIND environment
      variable is set. Fixes bug 30713; bugfix on 0.3.5.1-alpha.

  o Minor bugfixes (directory authorities):
    - Stop crashing after parsing an unknown descriptor purpose
      annotation. We think this bug can only be triggered by modifying a
      local file. Fixes bug 30781; bugfix on 0.2.0.8-alpha.

  o Minor bugfixes (pluggable transports):
    - When running as a bridge with pluggable transports, always publish
      pluggable transport information in our extrainfo descriptor, even
      if ExtraInfoStatistics is 0. This information is needed by
      BridgeDB. Fixes bug 30956; bugfix on 0.4.1.1-alpha.

  o Documentation:
    - Mention URLs for Travis/Appveyor/Jenkins in ReleasingTor.md.
      Closes ticket 30630.


Changes in version 0.4.1.2-alpha - 2019-06-06
  Tor 0.4.1.2-alpha resolves numerous bugs--some of them from the
  previous alpha, and some much older. It also contains minor testing
  improvements, and an improvement to the security of our authenticated
  SENDME implementation.

  o Major bugfixes (bridges):
    - Consider our directory information to have changed when our list
      of bridges changes. Previously, Tor would not re-compute the
      status of its directory information when bridges changed, and
      therefore would not realize that it was no longer able to build
      circuits. Fixes part of bug 29875.
    - Do not count previously configured working bridges towards our
      total of working bridges. Previously, when Tor's list of bridges
      changed, it would think that the old bridges were still usable,
      and delay fetching router descriptors for the new ones. Fixes part
      of bug 29875; bugfix on 0.3.0.1-alpha.

  o Major bugfixes (flow control, SENDME):
    - Decrement the stream-level package window after packaging a cell.
      Previously, it was done inside a log_debug() call, meaning that if
      debug logs were not enabled, the decrement would never happen, and
      thus the window would be out of sync with the other end point.
      Fixes bug 30628; bugfix on 0.4.1.1-alpha.

  o Major bugfixes (onion service reachability):
    - Properly clean up the introduction point map and associated state
      when circuits change purpose from onion service circuits to
      pathbias, measurement, or other circuit types. This may fix some
      instances of introduction point failure. Fixes bug 29034; bugfix
      on 0.3.2.1-alpha.

  o Minor features (authenticated SENDME):
    - Ensure that there is enough randomness on every circuit to prevent
      an attacker from successfully predicting the hashes they will need
      to include in authenticated SENDME cells. At a random interval, if
      we have not sent randomness already, we now leave some extra space
      at the end of a cell that we can fill with random bytes. Closes
      ticket 26846.

  o Minor features (continuous integration):
    - When running coverage builds on Travis, we now set
      TOR_TEST_RNG_SEED, to avoid RNG-based coverage differences. Part
      of ticket 28878.

  o Minor features (maintenance):
    - Add a new "make autostyle" target that developers can use to apply
      all automatic Tor style and consistency conversions to the
      codebase. Closes ticket 30539.

  o Minor features (testing):
    - The circuitpadding tests now use a reproducible RNG implementation,
      so that if a test fails, we can learn why. Part of ticket 28878.
    - Tor's tests now support an environment variable, TOR_TEST_RNG_SEED,
      to set the RNG seed for tests that use a reproducible RNG. Part of
      ticket 28878.
    - When running tests in coverage mode, take additional care to make
      our coverage deterministic, so that we can accurately track
      changes in code coverage. Closes ticket 30519.

  o Minor bugfixes (configuration, proxies):
    - Fix a bug that prevented us from supporting SOCKS5 proxies that
      want authentication along with configured (but unused!)
      ClientTransportPlugins. Fixes bug 29670; bugfix on 0.2.6.1-alpha.

  o Minor bugfixes (controller):
    - POSTDESCRIPTOR requests should work again. Previously, they were
      broken if a "purpose=" flag was specified. Fixes bug 30580; bugfix
      on 0.4.1.1-alpha.
    - Repair the HSFETCH command so that it works again. Previously, it
      expected a body when it shouldn't have. Fixes bug 30646; bugfix
      on 0.4.1.1-alpha.

  o Minor bugfixes (developer tooling):
    - Fix pre-push hook to allow fixup and squash commits when pushing
      to non-upstream git remote. Fixes bug 30286; bugfix
      on 0.4.0.1-alpha.

  o Minor bugfixes (directory authority):
    - Move the "bandwidth-file-headers" line in directory authority
      votes so that it conforms to dir-spec.txt. Fixes bug 30316; bugfix
      on 0.3.5.1-alpha.

  o Minor bugfixes (NetBSD):
    - Fix usage of minherit() on NetBSD and other platforms that define
      MAP_INHERIT_{ZERO,NONE} instead of INHERIT_{ZERO,NONE}. Fixes bug
      30614; bugfix on 0.4.0.2-alpha. Patch from Taylor Campbell.

  o Minor bugfixes (out-of-memory handler):
    - When purging the DNS cache because of an out-of-memory condition,
      try purging just the older entries at first. Previously, we would
      always purge the whole thing. Fixes bug 29617; bugfix
      on 0.3.5.1-alpha.

  o Minor bugfixes (portability):
    - Avoid crashing in our tor_vasprintf() implementation on systems
      that define neither vasprintf() nor _vscprintf(). (This bug has
      been here long enough that we question whether people are running
      Tor on such systems, but we're applying the fix out of caution.)
      Fixes bug 30561; bugfix on 0.2.8.2-alpha. Found and fixed by
      Tobias Stoeckmann.

  o Minor bugfixes (shutdown, libevent, memory safety):
    - Avoid use-after-free bugs when shutting down, by making sure that
      we shut down libevent only after shutting down all of its users.
      We believe these are harmless in practice, since they only occur
      on the shutdown path, and do not involve any attacker-controlled
      data. Fixes bug 30629; bugfix on 0.4.1.1-alpha.

  o Minor bugfixes (static analysis):
    - Fix several spurious Coverity warnings about the unit tests, to
      lower our chances of missing real warnings in the future. Fixes
      bug 30150; bugfix on 0.3.5.1-alpha and various other Tor versions.

  o Testing:
    - Specify torrc paths (with empty files) when launching tor in
      integration tests; refrain from reading user and system torrcs.
      Resolves issue 29702.


Changes in version 0.4.1.1-alpha - 2019-05-22
  This is the first alpha in the 0.4.1.x series. It introduces
  lightweight circuit padding to make some onion-service circuits harder
  to distinguish, includes a new "authenticated SENDME" feature to make
  certain denial-of-service attacks more difficult, and improves
  performance in several areas.

  o Major features (circuit padding):
    - Onion service clients now add padding cells at the start of their
      INTRODUCE and RENDEZVOUS circuits, to make those circuits' traffic
      look more like general purpose Exit traffic. The overhead for this
      is 2 extra cells in each direction for RENDEZVOUS circuits, and 1
      extra upstream cell and 10 downstream cells for INTRODUCE
      circuits. This feature is only enabled when also supported by the
      circuit's middle node. (Clients may specify fixed middle nodes
      with the MiddleNodes option, and may force-disable this feature
      with the CircuitPadding option.) Closes ticket 28634.

  o Major features (code organization):
    - Tor now includes a generic publish-subscribe message-passing
      subsystem that we can use to organize intermodule dependencies. We
      hope to use this to reduce dependencies between modules that don't
      need to be related, and to generally simplify our codebase. Closes
      ticket 28226.

  o Major features (controller protocol):
    - Controller commands are now parsed using a generalized parsing
      subsystem. Previously, each controller command was responsible for
      parsing its own input, which led to strange inconsistencies.
      Closes ticket 30091.

  o Major features (flow control):
    - Implement authenticated SENDMEs as detailed in proposal 289. A
      SENDME cell now includes the digest of the traffic that it
      acknowledges, so that once an end point receives the SENDME, it
      can confirm the other side's knowledge of the previous cells that
      were sent, and prevent certain types of denial-of-service attacks.
      This behavior is controlled by two new consensus parameters: see
      the proposal for more details. Fixes ticket 26288.

  o Major features (performance):
    - Our node selection algorithm now excludes nodes in linear time.
      Previously, the algorithm was quadratic, which could slow down
      heavily used onion services. Closes ticket 30307.

  o Major features (performance, RNG):
    - Tor now constructs a fast secure pseudorandom number generator for
      each thread, to use when performance is critical. This PRNG is
      based on AES-CTR, using a buffering construction similar to
      libottery and the (newer) OpenBSD arc4random() code. It
      outperforms OpenSSL 1.1.1a's CSPRNG by roughly a factor of 100 for
      small outputs. Although we believe it to be cryptographically
      strong, we are only using it when necessary for performance.
      Implements tickets 29023 and 29536.

  o Major bugfixes (onion service v3):
    - Fix an unreachable bug in which an introduction point could try to
      send an INTRODUCE_ACK with a status code that Trunnel would refuse
      to encode, leading the relay to assert(). We've consolidated the
      ABI values into Trunnel now. Fixes bug 30454; bugfix
      on 0.3.0.1-alpha.
    - Clients can now handle unknown status codes from INTRODUCE_ACK
      cells. (The NACK behavior will stay the same.) This will allow us
      to extend status codes in the future without breaking the normal
      client behavior. Fixes another part of bug 30454; bugfix
      on 0.3.0.1-alpha.

  o Minor features (circuit padding):
    - We now use a fast PRNG when scheduling circuit padding. Part of
      ticket 28636.
    - Allow the padding machine designer to pick the edges of their
      histogram instead of trying to compute them automatically using an
      exponential formula. Resolves some undefined behavior in the case
      of small histograms and allows greater flexibility on machine
      design. Closes ticket 29298; bugfix on 0.4.0.1-alpha.
    - Allow circuit padding machines to hold a circuit open until they
      are done padding it. Closes ticket 28780.

  o Minor features (compile-time modules):
    - Add a "--list-modules" command to print a list of which compile-
      time modules are enabled. Closes ticket 30452.

  o Minor features (continuous integration):
    - Remove sudo configuration lines from .travis.yml as they are no
      longer needed with current Travis build environment. Resolves
      issue 30213.
    - In Travis, show stem's tor log after failure. Closes ticket 30234.

  o Minor features (controller):
    - Add onion service version 3 support to the HSFETCH command.
      Previously, only version 2 onion services were supported. Closes
      ticket 25417. Patch by Neel Chauhan.

  o Minor features (debugging):
    - Introduce tor_assertf() and tor_assertf_nonfatal() to enable
      logging of additional information during assert failure. Now we
      can use format strings to include information for trouble
      shooting. Resolves ticket 29662.

  o Minor features (defense in depth):
    - In smartlist_remove_keeporder(), set unused pointers to NULL, in
      case a bug causes them to be used later. Closes ticket 30176.
      Patch from Tobias Stoeckmann.
    - Tor now uses a cryptographically strong PRNG even for decisions
      that we do not believe are security-sensitive. Previously, for
      performance reasons, we had used a trivially predictable linear
      congruential generator algorithm for certain load-balancing and
      statistical sampling decisions. Now we use our fast RNG in those
      cases. Closes ticket 29542.

  o Minor features (developer tools):
    - Tor's "practracker" test script now checks for files and functions
      that seem too long and complicated. Existing overlong functions
      and files are accepted for now, but should eventually be
      refactored. Closes ticket 29221.
    - Add some scripts used for git maintenance to scripts/git. Closes
      ticket 29391.
    - Call practracker from pre-push and pre-commit git hooks to let
      developers know if they made any code style violations. Closes
      ticket 30051.
    - Add a script to check that each header has a well-formed and
      unique guard macro. Closes ticket 29756.

  o Minor features (geoip):
    - Update geoip and geoip6 to the May 13 2019 Maxmind GeoLite2
      Country database. Closes ticket 30522.

  o Minor features (HTTP tunnel):
    - Return an informative web page when the HTTPTunnelPort is used as
      an HTTP proxy. Closes ticket 27821, patch by "eighthave".

  o Minor features (IPv6, v3 onion services):
    - Make v3 onion services put IPv6 addresses in service descriptors.
      Before this change, service descriptors only contained IPv4
      addresses. Implements 26992.

  o Minor features (modularity):
    - The "--disable-module-dirauth" compile-time option now disables
      even more dirauth-only code. Closes ticket 30345.

  o Minor features (performance):
    - Use OpenSSL's implementations of SHA3 when available (in OpenSSL
      1.1.1 and later), since they tend to be faster than tiny-keccak.
      Closes ticket 28837.

  o Minor features (testing):
    - Tor's unit test code now contains helper functions to replace the
      PRNG with a deterministic or reproducible version for testing.
      Previously, various tests implemented this in various ways.
      Implements ticket 29732.
    - We now have a script, cov-test-determinism.sh, to identify places
      where our unit test coverage has become nondeterministic. Closes
      ticket 29436.
    - Check that representative subsets of values of `int` and `unsigned
      int` can be represented by `void *`. Resolves issue 29537.

  o Minor bugfixes (bridge authority):
    - Bridge authorities now set bridges as running or non-running when
      about to dump their status to a file. Previously, they set bridges
      as running in response to a GETINFO command, but those shouldn't
      modify data structures. Fixes bug 24490; bugfix on 0.2.0.13-alpha.
      Patch by Neel Chauhan.

  o Minor bugfixes (channel padding statistics):
    - Channel padding write totals and padding-enabled totals are now
      counted properly in relay extrainfo descriptors. Fixes bug 29231;
      bugfix on 0.3.1.1-alpha.

  o Minor bugfixes (circuit padding):
    - Add a "CircuitPadding" torrc option to disable circuit padding.
      Fixes bug 28693; bugfix on 0.4.0.1-alpha.
    - Allow circuit padding machines to specify that they do not
      contribute much overhead, and provide consensus flags and torrc
      options to force clients to only use these low overhead machines.
      Fixes bug 29203; bugfix on 0.4.0.1-alpha.
    - Provide a consensus parameter to fully disable circuit padding, to
      be used in emergency network overload situations. Fixes bug 30173;
      bugfix on 0.4.0.1-alpha.
    - The circuit padding subsystem will no longer schedule padding if
      dormant mode is enabled. Fixes bug 28636; bugfix on 0.4.0.1-alpha.
    - Inspect a circuit-level cell queue before sending padding, to
      avoid sending padding while too much data is already queued. Fixes
      bug 29204; bugfix on 0.4.0.1-alpha.
    - Avoid calling monotime_absolute_usec() in circuit padding machines
      that do not use token removal or circuit RTT estimation. Fixes bug
      29085; bugfix on 0.4.0.1-alpha.

  o Minor bugfixes (compilation, unusual configurations):
    - Avoid failures when building with the ALL_BUGS_ARE_FATAL option
      due to missing declarations of abort(), and prevent other such
      failures in the future. Fixes bug 30189; bugfix on 0.3.4.1-alpha.

  o Minor bugfixes (controller protocol):
    - Teach the controller parser to distinguish an object preceded by
      an argument list from one without. Previously, it couldn't
      distinguish an argument list from the first line of a multiline
      object. Fixes bug 29984; bugfix on 0.2.3.8-alpha.

  o Minor bugfixes (directory authority, ipv6):
    - Directory authorities with IPv6 support now always mark themselves
      as reachable via IPv6. Fixes bug 24338; bugfix on 0.2.4.1-alpha.
      Patch by Neel Chauhan.

  o Minor bugfixes (documentation):
    - Improve the documentation for using MapAddress with ".exit". Fixes
      bug 30109; bugfix on 0.1.0.1-rc.
    - Improve the monotonic time module and function documentation to
      explain what "monotonic" actually means, and document some results
      that have surprised people. Fixes bug 29640; bugfix
      on 0.2.9.1-alpha.
    - Use proper formatting when providing an example on quoting options
      that contain whitespace. Fixes bug 29635; bugfix on 0.2.3.18-rc.

  o Minor bugfixes (logging):
    - Do not log a warning when running with an OpenSSL version other
      than the one Tor was compiled with, if the two versions should be
      compatible. Previously, we would warn whenever the version was
      different. Fixes bug 30190; bugfix on 0.2.4.2-alpha.
    - Warn operators when the MyFamily option is set but ContactInfo is
      missing, as the latter should be set too. Fixes bug 25110; bugfix
      on 0.3.3.1-alpha.

  o Minor bugfixes (memory leak):
    - Avoid a minor memory leak that could occur on relays when failing
      to create a "keys" directory. Fixes bug 30148; bugfix
      on 0.3.3.1-alpha.

  o Minor bugfixes (onion services):
    - Avoid a GCC 9.1.1 warning (and possible crash depending on libc
      implemenation) when failing to load an onion service client
      authorization file. Fixes bug 30475; bugfix on 0.3.5.1-alpha.
    - When refusing to launch a controller's HSFETCH request because of
      rate-limiting, respond to the controller with a new response,
      "QUERY_RATE_LIMITED". Previously, we would log QUERY_NO_HSDIR for
      this case. Fixes bug 28269; bugfix on 0.3.1.1-alpha. Patch by
      Neel Chauhan.
    - When relaunching a circuit to a rendezvous service, mark the
      circuit as needing high-uptime routers as appropriate. Fixes bug
      17357; bugfix on 0.1.0.1-rc. Patch by Neel Chauhan.
    - Stop ignoring IPv6 link specifiers sent to v3 onion services.
      (IPv6 support for v3 onion services is still incomplete: see
      ticket 23493 for details.) Fixes bug 23588; bugfix on
      0.3.2.1-alpha. Patch by Neel Chauhan.

  o Minor bugfixes (onion services, performance):
    - When building circuits to onion services, call tor_addr_parse()
      less often. Previously, we called tor_addr_parse() in
      circuit_is_acceptable() even if its output wasn't used. This
      change should improve performance when building circuits. Fixes
      bug 22210; bugfix on 0.2.8.12. Patch by Neel Chauhan.

  o Minor bugfixes (performance):
    - When checking whether a node is a bridge, use a fast check to make
      sure that its identity is set. Previously, we used a constant-time
      check, which is not necessary in this case. Fixes bug 30308;
      bugfix on 0.3.5.1-alpha.

  o Minor bugfixes (pluggable transports):
    - Tor now sets TOR_PT_EXIT_ON_STDIN_CLOSE=1 for client transports as
      well as servers. Fixes bug 25614; bugfix on 0.2.7.1-alpha.

  o Minor bugfixes (probability distributions):
    - Refactor and improve parts of the probability distribution code
      that made Coverity complain. Fixes bug 29805; bugfix
      on 0.4.0.1-alpha.

  o Minor bugfixes (python):
    - Stop assuming that /usr/bin/python3 exists. For scripts that work
      with python2, use /usr/bin/python. Otherwise, use /usr/bin/env
      python3. Fixes bug 29913; bugfix on 0.2.5.3-alpha.

  o Minor bugfixes (relay):
    - When running as a relay, if IPv6Exit is set to 1 while ExitRelay
      is auto, act as if ExitRelay is 1. Previously, we would ignore
      IPv6Exit if ExitRelay was 0 or auto. Fixes bug 29613; bugfix on
      0.3.5.1-alpha. Patch by Neel Chauhan.

  o Minor bugfixes (stats):
    - When ExtraInfoStatistics is 0, stop including bandwidth usage
      statistics, GeoIPFile hashes, ServerTransportPlugin lines, and
      bridge statistics by country in extra-info documents. Fixes bug
      29018; bugfix on 0.2.4.1-alpha.

  o Minor bugfixes (testing):
    - Call setrlimit() to disable core dumps in test_bt_cl.c. Previously
      we used `ulimit -c` in test_bt.sh, which violates POSIX shell
      compatibility. Fixes bug 29061; bugfix on 0.3.5.1-alpha.
    - Fix some incorrect code in the v3 onion service unit tests. Fixes
      bug 29243; bugfix on 0.3.2.1-alpha.
    - In the "routerkeys/*" tests, check the return values of mkdir()
      for possible failures. Fixes bug 29939; bugfix on 0.2.7.2-alpha.
      Found by Coverity as CID 1444254.
    - Split test_utils_general() into several smaller test functions.
      This makes it easier to perform resource deallocation on assert
      failure, and fixes Coverity warnings CID 1444117 and CID 1444118.
      Fixes bug 29823; bugfix on 0.2.9.1-alpha.

  o Minor bugfixes (tor-resolve):
    - Fix a memory leak in tor-resolve that could happen if Tor gave it
      a malformed SOCKS response. (Memory leaks in tor-resolve don't
      actually matter, but it's good to fix them anyway.) Fixes bug
      30151; bugfix on 0.4.0.1-alpha.

  o Code simplification and refactoring:
    - Abstract out the low-level formatting of replies on the control
      port. Implements ticket 30007.
    - Add several assertions in an attempt to fix some Coverity
      warnings. Closes ticket 30149.
    - Introduce a connection_dir_buf_add() helper function that checks
      for compress_state of dir_connection_t and automatically writes a
      string to directory connection with or without compression.
      Resolves issue 28816.
    - Make the base32_decode() API return the number of bytes written,
      for consistency with base64_decode(). Closes ticket 28913.
    - Move most relay-only periodic events out of mainloop.c into the
      relay subsystem. Closes ticket 30414.
    - Refactor and encapsulate parts of the codebase that manipulate
      crypt_path_t objects. Resolves issue 30236.
    - Refactor several places in our code that Coverity incorrectly
      believed might have memory leaks. Closes ticket 30147.
    - Remove redundant return values in crypto_format, and the
      associated return value checks elsewhere in the code. Make the
      implementations in crypto_format consistent, and remove redundant
      code. Resolves ticket 29660.
    - Rename tor_mem_is_zero() to fast_mem_is_zero(), to emphasize that
      it is not a constant-time function. Closes ticket 30309.
    - Replace hs_desc_link_specifier_t with link_specifier_t, and remove
      all hs_desc_link_specifier_t-specific code. Fixes bug 22781;
      bugfix on 0.3.2.1-alpha.
    - Simplify v3 onion service link specifier handling code. Fixes bug
      23576; bugfix on 0.3.2.1-alpha.
    - Split crypto_digest.c into NSS code, OpenSSL code, and shared
      code. Resolves ticket 29108.
    - Split control.c into several submodules, in preparation for
      distributing its current responsibilities throughout the codebase.
      Closes ticket 29894.
    - Start to move responsibility for knowing about periodic events to
      the appropriate subsystems, so that the mainloop doesn't need to
      know all the periodic events in the rest of the codebase.
      Implements tickets 30293 and 30294.

  o Documentation:
    - Document how to find git commits and tags for bug fixes in
      CodingStandards.md. Update some file documentation. Closes
      ticket 30261.

  o Removed features:
    - Remove the linux-tor-prio.sh script from contrib/operator-tools
      directory. Resolves issue 29434.
    - Remove the obsolete OpenSUSE initscript. Resolves issue 30076.
    - Remove the obsolete script at contrib/dist/tor.sh.in. Resolves
      issue 30075.

  o Code simplification and refactoring (shell scripts):
    - Clean up many of our shell scripts to fix shellcheck warnings.
      These include autogen.sh (ticket 26069), test_keygen.sh (ticket
      29062), test_switch_id.sh (ticket 29065), test_rebind.sh (ticket
      29063), src/test/fuzz/minimize.sh (ticket 30079), test_rust.sh
      (ticket 29064), torify (ticket 29070), asciidoc-helper.sh (29926),
      fuzz_multi.sh (30077), fuzz_static_testcases.sh (ticket 29059),
      nagios-check-tor-authority-cert (ticket 29071),
      src/test/fuzz/fixup_filenames.sh (ticket 30078), test-network.sh
      (ticket 29060), test_key_expiration.sh (ticket 30002),
      zero_length_keys.sh (ticket 29068), and test_workqueue_*.sh
      (ticket 29067).

  o Testing (chutney):
    - In "make test-network-all", test IPv6-only v3 single onion
      services, using the chutney network single-onion-v23-ipv6-md.
      Closes ticket 27251.


Changes in version 0.4.0.5 - 2019-05-02
  This is the first stable release in the 0.4.0.x series. It contains
  improvements for power management and bootstrap reporting, as well as
  preliminary backend support for circuit padding to prevent some kinds
  of traffic analysis. It also continues our work in refactoring Tor for
  long-term maintainability.

  Per our support policy, we will support the 0.4.0.x series for nine
  months, or until three months after the release of a stable 0.4.1.x:
  whichever is longer. If you need longer-term support, please stick
  with 0.3.5.x, which will we plan to support until Feb 2022.

  Below are the changes since 0.4.0.4-rc. For a complete list of changes
  since 0.3.5.7, see the ReleaseNotes file.

  o Minor features (continuous integration):
    - In Travis, tell timelimit to use stem's backtrace signals, and
      launch python directly from timelimit, so python receives the
      signals from timelimit, rather than make. Closes ticket 30117.

  o Minor features (diagnostic):
    - Add more diagnostic log messages in an attempt to solve the issue
      of NUL bytes appearing in a microdescriptor cache. Related to
      ticket 28223.

  o Minor features (testing):
    - Use the approx_time() function when setting the "Expires" header
      in directory replies, to make them more testable. Needed for
      ticket 30001.

  o Minor bugfixes (rust):
    - Abort on panic in all build profiles, instead of potentially
      unwinding into C code. Fixes bug 27199; bugfix on 0.3.3.1-alpha.

  o Minor bugfixes (shellcheck):
    - Look for scripts in their correct locations during "make
      shellcheck". Previously we had looked in the wrong place during
      out-of-tree builds. Fixes bug 30263; bugfix on 0.4.0.1-alpha.

  o Minor bugfixes (testing):
    - Check the time in the "Expires" header using approx_time(). Fixes
      bug 30001; bugfix on 0.4.0.4-rc.

  o Minor bugfixes (UI):
    - Lower log level of unlink() errors during bootstrap. Fixes bug
      29930; bugfix on 0.4.0.1-alpha.


Changes in version 0.4.0.4-rc - 2019-04-11
  Tor 0.4.0.4-rc is the first release candidate in its series; it fixes
  several bugs from earlier versions, including some that had affected
  stability, and one that prevented relays from working with NSS.

  o Major bugfixes (NSS, relay):
    - When running with NSS, disable TLS 1.2 ciphersuites that use
      SHA384 for their PRF. Due to an NSS bug, the TLS key exporters for
      these ciphersuites don't work -- which caused relays to fail to
      handshake with one another when these ciphersuites were enabled.
      Fixes bug 29241; bugfix on 0.3.5.1-alpha.

  o Minor features (bandwidth authority):
    - Make bandwidth authorities ignore relays that are reported in the
      bandwidth file with the flag "vote=0". This change allows us to
      report unmeasured relays for diagnostic reasons without including
      their bandwidth in the bandwidth authorities' vote. Closes
      ticket 29806.
    - When a directory authority is using a bandwidth file to obtain the
      bandwidth values that will be included in the next vote, serve
      this bandwidth file at /tor/status-vote/next/bandwidth. Closes
      ticket 21377.

  o Minor features (circuit padding):
    - Stop warning about undefined behavior in the probability
      distribution tests. Float division by zero may technically be
      undefined behavior in C, but it's well defined in IEEE 754.
      Partial backport of 29298. Closes ticket 29527; bugfix
      on 0.4.0.1-alpha.

  o Minor features (continuous integration):
    - On Travis Rust builds, cleanup Rust registry and refrain from
      caching the "target/" directory to speed up builds. Resolves
      issue 29962.

  o Minor features (dormant mode):
    - Add a DormantCanceledByStartup option to tell Tor that it should
      treat a startup event as cancelling any previous dormant state.
      Integrators should use this option with caution: it should only be
      used if Tor is being started because of something that the user
      did, and not if Tor is being automatically started in the
      background. Closes ticket 29357.

  o Minor features (geoip):
    - Update geoip and geoip6 to the April 2 2019 Maxmind GeoLite2
      Country database. Closes ticket 29992.

  o Minor features (NSS, diagnostic):
    - Try to log an error from NSS (if there is any) and a more useful
      description of our situation if we are using NSS and a call to
      SSL_ExportKeyingMaterial() fails. Diagnostic for ticket 29241.

  o Minor bugfixes (security):
    - Fix a potential double free bug when reading huge bandwidth files.
      The issue is not exploitable in the current Tor network because
      the vulnerable code is only reached when directory authorities
      read bandwidth files, but bandwidth files come from a trusted
      source (usually the authorities themselves). Furthermore, the
      issue is only exploitable in rare (non-POSIX) 32-bit architectures,
      which are not used by any of the current authorities. Fixes bug
      30040; bugfix on 0.3.5.1-alpha. Bug found and fixed by
      Tobias Stoeckmann.
    - Verify in more places that we are not about to create a buffer
      with more than INT_MAX bytes, to avoid possible OOB access in the
      event of bugs. Fixes bug 30041; bugfix on 0.2.0.16. Found and
      fixed by Tobias Stoeckmann.

  o Minor bugfix (continuous integration):
    - Reset coverage state on disk after Travis CI has finished. This
      should prevent future coverage merge errors from causing the test
      suite for the "process" subsystem to fail. The process subsystem
      was introduced in 0.4.0.1-alpha. Fixes bug 29036; bugfix
      on 0.2.9.15.
    - Terminate test-stem if it takes more than 9.5 minutes to run.
      (Travis terminates the job after 10 minutes of no output.)
      Diagnostic for 29437. Fixes bug 30011; bugfix on 0.3.5.4-alpha.

  o Minor bugfixes (bootstrap reporting):
    - During bootstrap reporting, correctly distinguish pluggable
      transports from plain proxies. Fixes bug 28925; bugfix
      on 0.4.0.1-alpha.

  o Minor bugfixes (C correctness):
    - Fix an unlikely memory leak in consensus_diff_apply(). Fixes bug
      29824; bugfix on 0.3.1.1-alpha. This is Coverity warning
      CID 1444119.

  o Minor bugfixes (circuitpadding testing):
    - Minor tweaks to avoid rare test failures related to timers and
      monotonic time. Fixes bug 29500; bugfix on 0.4.0.1-alpha.

  o Minor bugfixes (directory authorities):
    - Actually include the bandwidth-file-digest line in directory
      authority votes. Fixes bug 29959; bugfix on 0.4.0.2-alpha.

  o Minor bugfixes (logging):
    - On Windows, when errors cause us to reload a consensus from disk,
      tell the user that we are retrying at log level "notice".
      Previously we only logged this information at "info", which was
      confusing because the errors themselves were logged at "warning".
      Improves previous fix for 28614. Fixes bug 30004; bugfix
      on 0.4.0.2-alpha.

  o Minor bugfixes (pluggable transports):
    - Restore old behavior when it comes to discovering the path of a
      given Pluggable Transport executable file. A change in
      0.4.0.1-alpha had broken this behavior on paths containing a
      space. Fixes bug 29874; bugfix on 0.4.0.1-alpha.

  o Minor bugfixes (testing):
    - Backport the 0.3.4 src/test/test-network.sh to 0.2.9. We need a
      recent test-network.sh to use new chutney features in CI. Fixes
      bug 29703; bugfix on 0.2.9.1-alpha.
    - Fix a test failure on Windows caused by an unexpected "BUG"
      warning in our tests for tor_gmtime_r(-1). Fixes bug 29922; bugfix
      on 0.2.9.3-alpha.

  o Minor bugfixes (TLS protocol):
    - When classifying a client's selection of TLS ciphers, if the
      client ciphers are not yet available, do not cache the result.
      Previously, we had cached the unavailability of the cipher list
      and never looked again, which in turn led us to assume that the
      client only supported the ancient V1 link protocol. This, in turn,
      was causing Stem integration tests to stall in some cases. Fixes
      bug 30021; bugfix on 0.2.4.8-alpha.

  o Code simplification and refactoring:
    - Introduce a connection_dir_buf_add() helper function that detects
      whether compression is in use, and adds a string accordingly.
      Resolves issue 28816.
    - Refactor handle_get_next_bandwidth() to use
      connection_dir_buf_add(). Implements ticket 29897.

  o Documentation:
    - Clarify that Tor performs stream isolation among *Port listeners
      by default. Resolves issue 29121.


Changes in version 0.4.0.3-alpha - 2019-03-22
  Tor 0.4.0.3-alpha is the third in its series; it fixes several small
  bugs from earlier versions.

  o Minor features (address selection):
    - Treat the subnet 100.64.0.0/10 as public for some purposes;
      private for others. This subnet is the RFC 6598 (Carrier Grade
      NAT) IP range, and is deployed by many ISPs as an alternative to
      RFC 1918 that does not break existing internal networks. Tor now
      blocks SOCKS and control ports on these addresses and warns users
      if client ports or ExtORPorts are listening on a RFC 6598 address.
      Closes ticket 28525. Patch by Neel Chauhan.

  o Minor features (geoip):
    - Update geoip and geoip6 to the March 4 2019 Maxmind GeoLite2
      Country database. Closes ticket 29666.

  o Minor bugfixes (circuitpadding):
    - Inspect the circuit-level cell queue before sending padding, to
      avoid sending padding when too much data is queued. Fixes bug
      29204; bugfix on 0.4.0.1-alpha.

  o Minor bugfixes (logging):
    - Correct a misleading error message when IPv4Only or IPv6Only is
      used but the resolved address can not be interpreted as an address
      of the specified IP version. Fixes bug 13221; bugfix on
      0.2.3.9-alpha. Patch from Kris Katterjohn.
    - Log the correct port number for listening sockets when "auto" is
      used to let Tor pick the port number. Previously, port 0 was
      logged instead of the actual port number. Fixes bug 29144; bugfix
      on 0.3.5.1-alpha. Patch from Kris Katterjohn.
    - Stop logging a BUG() warning when Tor is waiting for exit
      descriptors. Fixes bug 28656; bugfix on 0.3.5.1-alpha.

  o Minor bugfixes (memory management):
    - Refactor the shared random state's memory management so that it
      actually takes ownership of the shared random value pointers.
      Fixes bug 29706; bugfix on 0.2.9.1-alpha.

  o Minor bugfixes (memory management, testing):
    - Stop leaking parts of the shared random state in the shared-random
      unit tests. Fixes bug 29599; bugfix on 0.2.9.1-alpha.

  o Minor bugfixes (pluggable transports):
    - Fix an assertion failure crash bug when a pluggable transport is
      terminated during the bootstrap phase. Fixes bug 29562; bugfix
      on 0.4.0.1-alpha.

  o Minor bugfixes (Rust, protover):
    - Add a missing "Padding" value to the Rust implementation of
      protover. Fixes bug 29631; bugfix on 0.4.0.1-alpha.

  o Minor bugfixes (single onion services):
    - Allow connections to single onion services to remain idle without
      being disconnected. Previously, relays acting as rendezvous points
      for single onion services were mistakenly closing idle rendezvous
      circuits after 60 seconds, thinking that they were unused
      directory-fetching circuits that had served their purpose. Fixes
      bug 29665; bugfix on 0.2.1.26.

  o Minor bugfixes (stats):
    - When ExtraInfoStatistics is 0, stop including PaddingStatistics in
      relay and bridge extra-info documents. Fixes bug 29017; bugfix
      on 0.3.1.1-alpha.

  o Minor bugfixes (testing):
    - Downgrade some LOG_ERR messages in the address/* tests to
      warnings. The LOG_ERR messages were occurring when we had no
      configured network. We were failing the unit tests, because we
      backported 28668 to 0.3.5.8, but did not backport 29530. Fixes bug
      29530; bugfix on 0.3.5.8.
    - Fix our gcov wrapper script to look for object files at the
      correct locations. Fixes bug 29435; bugfix on 0.3.5.1-alpha.
    - Decrease the false positive rate of stochastic probability
      distribution tests. Fixes bug 29693; bugfix on 0.4.0.1-alpha.

  o Minor bugfixes (Windows, CI):
    - Skip the Appveyor 32-bit Windows Server 2016 job, and 64-bit
      Windows Server 2012 R2 job. The remaining 2 jobs still provide
      coverage of 64/32-bit, and Windows Server 2016/2012 R2. Also set
      fast_finish, so failed jobs terminate the build immediately. Fixes
      bug 29601; bugfix on 0.3.5.4-alpha.


Changes in version 0.3.5.8 - 2019-02-21
  Tor 0.3.5.8 backports several fixes from later releases, including fixes
  for an annoying SOCKS-parsing bug that affected users in earlier 0.3.5.x
  releases.

  It also includes a fix for a medium-severity security bug affecting Tor
  0.3.2.1-alpha and later. All Tor instances running an affected release
  should upgrade to 0.3.3.12, 0.3.4.11, 0.3.5.8, or 0.4.0.2-alpha.

  o Major bugfixes (cell scheduler, KIST, security):
    - Make KIST consider the outbuf length when computing what it can
      put in the outbuf. Previously, KIST acted as though the outbuf
      were empty, which could lead to the outbuf becoming too full. It
      is possible that an attacker could exploit this bug to cause a Tor
      client or relay to run out of memory and crash. Fixes bug 29168;
      bugfix on 0.3.2.1-alpha. This issue is also being tracked as
      TROVE-2019-001 and CVE-2019-8955.

  o Major bugfixes (networking, backport from 0.4.0.2-alpha):
    - Gracefully handle empty username/password fields in SOCKS5
      username/password auth message and allow SOCKS5 handshake to
      continue. Previously, we had rejected these handshakes, breaking
      certain applications. Fixes bug 29175; bugfix on 0.3.5.1-alpha.

  o Minor features (compilation, backport from 0.4.0.2-alpha):
    - Compile correctly when OpenSSL is built with engine support
      disabled, or with deprecated APIs disabled. Closes ticket 29026.
      Patches from "Mangix".

  o Minor features (geoip):
    - Update geoip and geoip6 to the February 5 2019 Maxmind GeoLite2
      Country database. Closes ticket 29478.

  o Minor features (testing, backport from 0.4.0.2-alpha):
    - Treat all unexpected ERR and BUG messages as test failures. Closes
      ticket 28668.

  o Minor bugfixes (onion service v3, client, backport from 0.4.0.1-alpha):
    - Stop logging a "BUG()" warning and stacktrace when we find a SOCKS
      connection waiting for a descriptor that we actually have in the
      cache. It turns out that this can actually happen, though it is
      rare. Now, tor will recover and retry the descriptor. Fixes bug
      28669; bugfix on 0.3.2.4-alpha.

  o Minor bugfixes (IPv6, backport from 0.4.0.1-alpha):
    - Fix tor_ersatz_socketpair on IPv6-only systems. Previously, the
      IPv6 socket was bound using an address family of AF_INET instead
      of AF_INET6. Fixes bug 28995; bugfix on 0.3.5.1-alpha. Patch from
      Kris Katterjohn.

  o Minor bugfixes (build, compatibility, rust, backport from 0.4.0.2-alpha):
    - Update Cargo.lock file to match the version made by the latest
      version of Rust, so that "make distcheck" will pass again. Fixes
      bug 29244; bugfix on 0.3.3.4-alpha.

  o Minor bugfixes (client, clock skew, backport from 0.4.0.1-alpha):
    - Select guards even if the consensus has expired, as long as the
      consensus is still reasonably live. Fixes bug 24661; bugfix
      on 0.3.0.1-alpha.

  o Minor bugfixes (compilation, backport from 0.4.0.1-alpha):
    - Compile correctly on OpenBSD; previously, we were missing some
      headers required in order to detect it properly. Fixes bug 28938;
      bugfix on 0.3.5.1-alpha. Patch from Kris Katterjohn.

  o Minor bugfixes (documentation, backport from 0.4.0.2-alpha):
    - Describe the contents of the v3 onion service client authorization
      files correctly: They hold public keys, not private keys. Fixes
      bug 28979; bugfix on 0.3.5.1-alpha. Spotted by "Felixix".

  o Minor bugfixes (logging, backport from 0.4.0.1-alpha):
    - Rework rep_hist_log_link_protocol_counts() to iterate through all
      link protocol versions when logging incoming/outgoing connection
      counts. Tor no longer skips version 5, and we won't have to
      remember to update this function when new link protocol version is
      developed. Fixes bug 28920; bugfix on 0.2.6.10.

  o Minor bugfixes (logging, backport from 0.4.0.2-alpha):
    - Log more information at "warning" level when unable to read a
      private key; log more information at "info" level when unable to
      read a public key. We had warnings here before, but they were lost
      during our NSS work. Fixes bug 29042; bugfix on 0.3.5.1-alpha.

  o Minor bugfixes (misc, backport from 0.4.0.2-alpha):
    - The amount of total available physical memory is now determined
      using the sysctl identifier HW_PHYSMEM (rather than HW_USERMEM)
      when it is defined and a 64-bit variant is not available. Fixes
      bug 28981; bugfix on 0.2.5.4-alpha. Patch from Kris Katterjohn.

  o Minor bugfixes (onion services, backport from 0.4.0.2-alpha):
    - Avoid crashing if ClientOnionAuthDir (incorrectly) contains more
      than one private key for a hidden service. Fixes bug 29040; bugfix
      on 0.3.5.1-alpha.
    - In hs_cache_store_as_client() log an HSDesc we failed to parse at
      "debug" level. Tor used to log it as a warning, which caused very
      long log lines to appear for some users. Fixes bug 29135; bugfix
      on 0.3.2.1-alpha.
    - Stop logging "Tried to establish rendezvous on non-OR circuit..."
      as a warning. Instead, log it as a protocol warning, because there
      is nothing that relay operators can do to fix it. Fixes bug 29029;
      bugfix on 0.2.5.7-rc.

  o Minor bugfixes (tests, directory clients, backport from 0.4.0.1-alpha):
    - Mark outdated dirservers when Tor only has a reasonably live
      consensus. Fixes bug 28569; bugfix on 0.3.2.5-alpha.

  o Minor bugfixes (tests, backport from 0.4.0.2-alpha):
    - Detect and suppress "bug" warnings from the util/time test on
      Windows. Fixes bug 29161; bugfix on 0.2.9.3-alpha.
    - Do not log an error-level message if we fail to find an IPv6
      network interface from the unit tests. Fixes bug 29160; bugfix
      on 0.2.7.3-rc.

  o Minor bugfixes (usability, backport from 0.4.0.1-alpha):
    - Stop saying "Your Guard ..." in pathbias_measure_{use,close}_rate().
      Some users took this phrasing to mean that the mentioned guard was
      under their control or responsibility, which it is not. Fixes bug
      28895; bugfix on Tor 0.3.0.1-alpha.


Changes in version 0.3.4.11 - 2019-02-21
  Tor 0.3.4.11 is the third stable release in its series.  It includes
  a fix for a medium-severity security bug affecting Tor 0.3.2.1-alpha and
  later. All Tor instances running an affected release should upgrade to
  0.3.3.12, 0.3.4.11, 0.3.5.8, or 0.4.0.2-alpha.

  o Major bugfixes (cell scheduler, KIST, security):
    - Make KIST consider the outbuf length when computing what it can
      put in the outbuf. Previously, KIST acted as though the outbuf
      were empty, which could lead to the outbuf becoming too full. It
      is possible that an attacker could exploit this bug to cause a Tor
      client or relay to run out of memory and crash. Fixes bug 29168;
      bugfix on 0.3.2.1-alpha. This issue is also being tracked as
      TROVE-2019-001 and CVE-2019-8955.

  o Minor features (geoip):
    - Update geoip and geoip6 to the February 5 2019 Maxmind GeoLite2
      Country database. Closes ticket 29478.

  o Minor bugfixes (build, compatibility, rust, backport from 0.4.0.2-alpha):
    - Update Cargo.lock file to match the version made by the latest
      version of Rust, so that "make distcheck" will pass again. Fixes
      bug 29244; bugfix on 0.3.3.4-alpha.

  o Minor bugfixes (onion services, backport from 0.4.0.2-alpha):
    - Stop logging "Tried to establish rendezvous on non-OR circuit..."
      as a warning. Instead, log it as a protocol warning, because there
      is nothing that relay operators can do to fix it. Fixes bug 29029;
      bugfix on 0.2.5.7-rc.


Changes in version 0.3.3.12 - 2019-02-21
  Tor 0.3.3.12 fixes a medium-severity security bug affecting Tor
  0.3.2.1-alpha and later. All Tor instances running an affected release
  should upgrade to 0.3.3.12, 0.3.4.11, 0.3.5.8, or 0.4.0.2-alpha.

  This release marks the end of support for the Tor 0.3.3.x series. We
  recommend that users switch to either the Tor 0.3.4 series (supported
  until at least 10 June 2019), or the Tor 0.3.5 series, which will
  receive long-term support until at least 1 Feb 2022.

  o Major bugfixes (cell scheduler, KIST, security):
    - Make KIST consider the outbuf length when computing what it can
      put in the outbuf. Previously, KIST acted as though the outbuf
      were empty, which could lead to the outbuf becoming too full. It
      is possible that an attacker could exploit this bug to cause a Tor
      client or relay to run out of memory and crash. Fixes bug 29168;
      bugfix on 0.3.2.1-alpha. This issue is also being tracked as
      TROVE-2019-001 and CVE-2019-8955.

  o Minor features (geoip):
    - Update geoip and geoip6 to the February 5 2019 Maxmind GeoLite2
      Country database. Closes ticket 29478.

  o Minor bugfixes (build, compatibility, rust, backport from 0.4.0.2-alpha):
    - Update Cargo.lock file to match the version made by the latest
      version of Rust, so that "make distcheck" will pass again. Fixes
      bug 29244; bugfix on 0.3.3.4-alpha.

  o Minor bugfixes (onion services, backport from 0.4.0.2-alpha):
    - Stop logging "Tried to establish rendezvous on non-OR circuit..."
      as a warning. Instead, log it as a protocol warning, because there
      is nothing that relay operators can do to fix it. Fixes bug 29029;
      bugfix on 0.2.5.7-rc.


Changes in version 0.4.0.2-alpha - 2019-02-21
  Tor 0.4.0.2-alpha is the second alpha in its series; it fixes several
  bugs from earlier versions, including several that had broken
  backward compatibility.

  It also includes a fix for a medium-severity security bug affecting Tor
  0.3.2.1-alpha and later. All Tor instances running an affected release
  should upgrade to 0.3.3.12, 0.3.4.11, 0.3.5.8, or 0.4.0.2-alpha.

  o Major bugfixes (cell scheduler, KIST, security):
    - Make KIST consider the outbuf length when computing what it can
      put in the outbuf. Previously, KIST acted as though the outbuf
      were empty, which could lead to the outbuf becoming too full. It
      is possible that an attacker could exploit this bug to cause a Tor
      client or relay to run out of memory and crash. Fixes bug 29168;
      bugfix on 0.3.2.1-alpha. This issue is also being tracked as
      TROVE-2019-001 and CVE-2019-8955.

  o Major bugfixes (networking):
    - Gracefully handle empty username/password fields in SOCKS5
      username/password auth messsage and allow SOCKS5 handshake to
      continue. Previously, we had rejected these handshakes, breaking
      certain applications. Fixes bug 29175; bugfix on 0.3.5.1-alpha.

  o Major bugfixes (windows, startup):
    - When reading a consensus file from disk, detect whether it was
      written in text mode, and re-read it in text mode if so. Always
      write consensus files in binary mode so that we can map them into
      memory later. Previously, we had written in text mode, which
      confused us when we tried to map the file on windows. Fixes bug
      28614; bugfix on 0.4.0.1-alpha.

  o Minor features (compilation):
    - Compile correctly when OpenSSL is built with engine support
      disabled, or with deprecated APIs disabled. Closes ticket 29026.
      Patches from "Mangix".

  o Minor features (developer tooling):
    - Check that bugfix versions in changes files look like Tor versions
      from the versions spec. Warn when bugfixes claim to be on a future
      release. Closes ticket 27761.
    - Provide a git pre-commit hook that disallows committing if we have
      any failures in our code and changelog formatting checks. It is
      now available in scripts/maint/pre-commit.git-hook. Implements
      feature 28976.

  o Minor features (directory authority):
    - When a directory authority is using a bandwidth file to obtain
      bandwidth values, include the digest of that file in the vote.
      Closes ticket 26698.

  o Minor features (geoip):
    - Update geoip and geoip6 to the February 5 2019 Maxmind GeoLite2
      Country database. Closes ticket 29478.

  o Minor features (testing):
    - Treat all unexpected ERR and BUG messages as test failures. Closes
      ticket 28668.

  o Minor bugfixes (build, compatibility, rust):
    - Update Cargo.lock file to match the version made by the latest
      version of Rust, so that "make distcheck" will pass again. Fixes
      bug 29244; bugfix on 0.3.3.4-alpha.

  o Minor bugfixes (compilation):
    - Fix compilation warnings in test_circuitpadding.c. Fixes bug
      29169; bugfix on 0.4.0.1-alpha.
    - Silence a compiler warning in test-memwipe.c on OpenBSD. Fixes bug
      29145; bugfix on 0.2.9.3-alpha. Patch from Kris Katterjohn.

  o Minor bugfixes (documentation):
    - Describe the contents of the v3 onion service client authorization
      files correctly: They hold public keys, not private keys. Fixes
      bug 28979; bugfix on 0.3.5.1-alpha. Spotted by "Felixix".

  o Minor bugfixes (linux seccomp sandbox):
    - Fix startup crash when experimental sandbox support is enabled.
      Fixes bug 29150; bugfix on 0.4.0.1-alpha. Patch by Peter Gerber.

  o Minor bugfixes (logging):
    - Avoid logging that we are relaxing a circuit timeout when that
      timeout is fixed. Fixes bug 28698; bugfix on 0.2.4.7-alpha.
    - Log more information at "warning" level when unable to read a
      private key; log more information at "info" level when unable to
      read a public key. We had warnings here before, but they were lost
      during our NSS work. Fixes bug 29042; bugfix on 0.3.5.1-alpha.

  o Minor bugfixes (misc):
    - The amount of total available physical memory is now determined
      using the sysctl identifier HW_PHYSMEM (rather than HW_USERMEM)
      when it is defined and a 64-bit variant is not available. Fixes
      bug 28981; bugfix on 0.2.5.4-alpha. Patch from Kris Katterjohn.

  o Minor bugfixes (onion services):
    - Avoid crashing if ClientOnionAuthDir (incorrectly) contains more
      than one private key for a hidden service. Fixes bug 29040; bugfix
      on 0.3.5.1-alpha.
    - In hs_cache_store_as_client() log an HSDesc we failed to parse at
      "debug" level. Tor used to log it as a warning, which caused very
      long log lines to appear for some users. Fixes bug 29135; bugfix
      on 0.3.2.1-alpha.
    - Stop logging "Tried to establish rendezvous on non-OR circuit..."
      as a warning. Instead, log it as a protocol warning, because there
      is nothing that relay operators can do to fix it. Fixes bug 29029;
      bugfix on 0.2.5.7-rc.

  o Minor bugfixes (scheduler):
    - When re-adding channels to the pending list, check the correct
      channel's sched_heap_idx. This issue has had no effect in mainline
      Tor, but could have led to bugs down the road in improved versions
      of our circuit scheduling code. Fixes bug 29508; bugfix
      on 0.3.2.10.

  o Minor bugfixes (tests):
    - Fix intermittent failures on an adaptive padding test. Fixes one
      case of bug 29122; bugfix on 0.4.0.1-alpha.
    - Disable an unstable circuit-padding test that was failing
      intermittently because of an ill-defined small histogram. Such
      histograms will be allowed again after 29298 is implemented. Fixes
      a second case of bug 29122; bugfix on 0.4.0.1-alpha.
    - Detect and suppress "bug" warnings from the util/time test on
      Windows. Fixes bug 29161; bugfix on 0.2.9.3-alpha.
    - Do not log an error-level message if we fail to find an IPv6
      network interface from the unit tests. Fixes bug 29160; bugfix
      on 0.2.7.3-rc.

  o Documentation:
    - In the manpage entry describing MapAddress torrc setting, use
      example IP addresses from ranges specified for use in documentation
      by RFC 5737. Resolves issue 28623.

  o Removed features:
    - Remove the old check-tor script. Resolves issue 29072.


Changes in version 0.4.0.1-alpha - 2019-01-18
  Tor 0.4.0.1-alpha is the first release in the new 0.4.0.x series. It
  introduces improved features for power and bandwidth conservation,
  more accurate reporting of bootstrap progress for user interfaces, and
  an experimental backend for an exciting new adaptive padding feature.
  There is also the usual assortment of bugfixes and minor features, all
  described below.

  o Major features (battery management, client, dormant mode):
    - When Tor is running as a client, and it is unused for a long time,
      it can now enter a "dormant" state. When Tor is dormant, it avoids
      network and CPU activity until it is reawoken either by a user
      request or by a controller command. For more information, see the
      configuration options starting with "Dormant". Implements tickets
      2149 and 28335.
    - The client's memory of whether it is "dormant", and how long it
      has spent idle, persists across invocations. Implements
      ticket 28624.
    - There is a DormantOnFirstStartup option that integrators can use
      if they expect that in many cases, Tor will be installed but
      not used.

  o Major features (bootstrap reporting):
    - When reporting bootstrap progress, report the first connection
      uniformly, regardless of whether it's a connection for building
      application circuits. This allows finer-grained reporting of early
      progress than previously possible, with the improvements of ticket
      27169. Closes tickets 27167 and 27103. Addresses ticket 27308.
    - When reporting bootstrap progress, treat connecting to a proxy or
      pluggable transport as separate from having successfully used that
      proxy or pluggable transport to connect to a relay. Closes tickets
      27100 and 28884.

  o Major features (circuit padding):
    - Implement preliminary support for the circuit padding portion of
      Proposal 254. The implementation supports Adaptive Padding (aka
      WTF-PAD) state machines for use between experimental clients and
      relays. Support is also provided for APE-style state machines that
      use probability distributions instead of histograms to specify
      inter-packet delay. At the moment, Tor does not provide any
      padding state machines that are used in normal operation: for now,
      this feature exists solely for experimentation. Closes
      ticket 28142.

  o Major features (refactoring):
    - Tor now uses an explicit list of its own subsystems when
      initializing and shutting down. Previously, these systems were
      managed implicitly in various places throughout the codebase.
      (There may still be some subsystems using the old system.) Closes
      ticket 28330.

  o Minor features (bootstrap reporting):
    - When reporting bootstrap progress, stop distinguishing between
      situations where only internal paths are available and situations
      where external paths are available. Previously, Tor would often
      erroneously report that it had only internal paths. Closes
      ticket 27402.

  o Minor features (continuous integration):
    - Log Python version during each Travis CI job. Resolves
      issue 28551.

  o Minor features (controller):
    - Add a DROPOWNERSHIP command to undo the effects of TAKEOWNERSHIP.
      Implements ticket 28843.

  o Minor features (developer tooling):
    - Provide a git hook script to prevent "fixup!" and "squash!"
      commits from ending up in the master branch, as scripts/main/pre-
      push.git-hook. Closes ticket 27993.

  o Minor features (directory authority):
    - Directory authorities support a new consensus algorithm, under
      which the family lines in microdescriptors are encoded in a
      canonical form. This change makes family lines more compressible
      in transit, and on the client. Closes ticket 28266; implements
      proposal 298.

  o Minor features (directory authority, relay):
    - Authorities now vote on a "StaleDesc" flag to indicate that a
      relay's descriptor is so old that the relay should upload again
      soon. Relays treat this flag as a signal to upload a new
      descriptor. This flag will eventually let us remove the
      'published' date from routerstatus entries, and make our consensus
      diffs much smaller. Closes ticket 26770; implements proposal 293.

  o Minor features (fallback directory mirrors):
    - Update the fallback whitelist based on operator opt-ins and opt-
      outs. Closes ticket 24805, patch by Phoul.

  o Minor features (FreeBSD):
    - On FreeBSD-based systems, warn relay operators if the
      "net.inet.ip.random_id" sysctl (IP ID randomization) is disabled.
      Closes ticket 28518.

  o Minor features (HTTP standards compliance):
    - Stop sending the header "Content-type: application/octet-stream"
      along with transparently compressed documents: this confused
      browsers. Closes ticket 28100.

  o Minor features (IPv6):
    - We add an option ClientAutoIPv6ORPort, to make clients randomly
      prefer a node's IPv4 or IPv6 ORPort. The random preference is set
      every time a node is loaded from a new consensus or bridge config.
      We expect that this option will enable clients to bootstrap more
      quickly without having to determine whether they support IPv4,
      IPv6, or both. Closes ticket 27490. Patch by Neel Chauhan.
    - When using addrs_in_same_network_family(), avoid choosing circuit
      paths that pass through the same IPv6 subnet more than once.
      Previously, we only checked IPv4 subnets. Closes ticket 24393.
      Patch by Neel Chauhan.

  o Minor features (log messages):
    - Improve log message in v3 onion services that could print out
      negative revision counters. Closes ticket 27707. Patch
      by "ffmancera".

  o Minor features (memory usage):
    - Save memory by storing microdescriptor family lists with a more
      compact representation. Closes ticket 27359.
    - Tor clients now use mmap() to read consensus files from disk, so
      that they no longer need keep the full text of a consensus in
      memory when parsing it or applying a diff. Closes ticket 27244.

  o Minor features (parsing):
    - Directory authorities now validate that router descriptors and
      ExtraInfo documents are in a valid subset of UTF-8, and reject
      them if they are not. Closes ticket 27367.