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[tor-talk] Tor is released!

(Also, was released last week.  If you didn't know, you should
subscribe to tor-announcements.)

Hi, all!

You can find the source code for Tor  www.torrpoject.org
at the usual place.  It's an alpha, so please expect plenty of bugs,
and be ready to report them.  Packages should be out over the next
weeks -- I'd expect this series to hit Tor Browser alpha releases some
time in the middle of June.

Changes in version - 2017-05-22
  Tor is the first release in the 0.3.1.x series. It
  reduces the bandwidth usage for Tor's directory protocol, adds some
  basic padding to resist netflow-based traffic analysis and to serve as
  the basis of other padding in the future, and adds rust support to the
  build system.

  It also contains numerous other small features and improvements to
  security, correctness, and performance.

  Below are the changes since

  o Major features (directory protocol):
    - Tor relays and authorities can now serve clients an abbreviated
      version of the consensus document, containing only the changes
      since an older consensus document that the client holds. Clients
      now request these documents when available. When both client and
      server use this new protocol, they will use far less bandwidth (up
      to 94% less) to keep the client's consensus up-to-date. Implements
      proposal 140; closes ticket 13339. Based on work by Daniel Martí.
    - Tor can now compress directory traffic with lzma or with zstd
      compression algorithms, which can deliver better bandwidth
      performance. Because lzma is computationally expensive, it's only
      used for documents that can be compressed once and served many
      times. Support for these algorithms requires that tor is built
      with the libzstd and/or liblzma libraries available. Implements
      proposal 278; closes ticket 21662.
    - Relays now perform the more expensive compression operations, and
      consensus diff generation, in worker threads. This separation
      avoids delaying the main thread when a new consensus arrives.

  o Major features (experimental):
    - Tor can now build modules written in Rust. To turn this on, pass
      the "--enable-rust" flag to the configure script. It's not time to
      get excited yet: currently, there is no actual Rust functionality
      beyond some simple glue code, and a notice at startup to tell you
      that Rust is running. Still, we hope that programmers and
      packagers will try building Tor with Rust support, so that we can
      find issues and solve portability problems. Closes ticket 22106.

  o Major features (traffic analysis resistance):
    - Connections between clients and relays now send a padding cell in
      each direction every 1.5 to 9.5 seconds (tunable via consensus
      parameters). This padding will not resist specialized
      eavesdroppers, but it should be enough to make many ISPs' routine
      network flow logging less useful in traffic analysis against
      Tor users.

      Padding is negotiated using Tor's link protocol, so both relays
      and clients must upgrade for this to take effect. Clients may
      still send padding despite the relay's version by setting
      ConnectionPadding 1 in torrc, and may disable padding by setting
      ConnectionPadding 0 in torrc. Padding may be minimized for mobile
      users with the torrc option ReducedConnectionPadding. Implements
      Proposal 251 and Section 2 of Proposal 254; closes ticket 16861.
    - Relays will publish 24 hour totals of padding and non-padding cell
      counts to their extra-info descriptors, unless PaddingStatistics 0
      is set in torrc. These 24 hour totals are also rounded to
      multiples of 10000.

  o Major bugfixes (connection usage):
    - We use NETINFO cells to try to determine if both relays involved
      in a connection will agree on the canonical status of that
      connection. We prefer the connections where this is the case for
      extend cells, and try to close connections where relays disagree
      on their canonical status early. Also, we now prefer the oldest
      valid connection for extend cells. These two changes should reduce
      the number of long-term connections that are kept open between
      relays. Fixes bug 17604; bugfix on
    - Relays now log hourly statistics (look for
      "channel_check_for_duplicates" lines) on the total number of
      connections to other relays. If the number of connections per
      relay is unexpectedly large, this log message is at notice level.
      Otherwise it is at info.

  o Major bugfixes (entry guards):
    - Don't block bootstrapping when a primary bridge is offline and we
      can't get its descriptor. Fixes bug 22325; fixes one case of bug
      21969; bugfix on

  o Major bugfixes (linux TPROXY support):
    - Fix a typo that had prevented TPROXY-based transparent proxying
      from working under Linux. Fixes bug 18100; bugfix on
      Patch from "d4fq0fQAgoJ".

  o Minor features (security, windows):
    - Enable a couple of pieces of Windows hardening: one
      (HeapEnableTerminationOnCorruption) that has been on-by-default
      since Windows 8, and unavailable before Windows 7; and one
      (PROCESS_DEP_DISABLE_ATL_THUNK_EMULATION) which we believe doesn't
      affect us, but shouldn't do any harm. Closes ticket 21953.

  o Minor features (config options):
    - Allow "%include" directives in torrc configuration files. These
      directives import the settings from other files, or from all the
      files in a directory. Closes ticket 1922. Code by Daniel Pinto.
    - Make SAVECONF return an error when overwriting a torrc that has
      includes. Using SAVECONF with the FORCE option will allow it to
      overwrite torrc even if includes are used. Related to ticket 1922.
    - Add "GETINFO config-can-saveconf" to tell controllers if SAVECONF
      will work without the FORCE option. Related to ticket 1922.

  o Minor features (controller):
    - Warn the first time that a controller requests data in the long-
      deprecated 'GETINFO network-status' format. Closes ticket 21703.

  o Minor features (defaults):
    - The default value for UseCreateFast is now 0: clients which
      haven't yet received a consensus document will now use a proper
      ntor handshake to talk to their directory servers whenever they
      can. Closes ticket 21407.
    - Onion key rotation and expiry intervals are now defined as a
      network consensus parameter, per proposal 274. The default
      lifetime of an onion key is increased from 7 to 28 days. Old onion
      keys will expire after 7 days by default. This change will make
      consensus diffs much smaller, and save significant bandwidth.
      Closes ticket 21641.

  o Minor features (fallback directory list):
    - Update the fallback directory mirror whitelist and blacklist based
      on operator emails. Closes task 21121.
    - Replace the 177 fallbacks originally introduced in Tor in
      December 2016 (of which ~126 were still functional) with a list of
      151 fallbacks (32 new, 119 unchanged, 58 removed) generated in May
      2017. Resolves ticket 21564.

  o Minor features (hidden services, logging):
    - Log a message when a hidden service descriptor has fewer
      introduction points than specified in
      HiddenServiceNumIntroductionPoints. Closes tickets 21598.
    - Log a message when a hidden service reaches its introduction point
      circuit limit, and when that limit is reset. Follow up to ticket
      21594; closes ticket 21622.
    - Warn user if multiple entries in EntryNodes and at least one
      HiddenService are used together. Pinning EntryNodes along with a
      hidden service can be possibly harmful; for instance see ticket
      14917 or 21155. Closes ticket 21155.

  o Minor features (linux seccomp2 sandbox):
    - We now have a document storage backend compatible with the Linux
      seccomp2 sandbox. This backend is used for consensus documents and
      diffs between them; in the long term, we'd like to use it for
      unparseable directory material too. Closes ticket 21645
    - Increase the maximum allowed size passed to mprotect(PROT_WRITE)
      from 1MB to 16MB. This was necessary with the glibc allocator in
      order to allow worker threads to allocate more memory -- which in
      turn is necessary because of our new use of worker threads for
      compression. Closes ticket 22096.

  o Minor features (logging):
    - Log files are no longer created world-readable by default.
      (Previously, most distributors would store the logs in a non-
      world-readable location to prevent inappropriate access. This
      change is an extra precaution.) Closes ticket 21729; patch
      from toralf.

  o Minor features (performance):
    - Our Keccak (SHA-3) implementation now accesses memory more
      efficiently, especially on little-endian systems. Closes
      ticket 21737.
    - Add an O(1) implementation of channel_find_by_global_id(), to
      speed some controller functions.

  o Minor features (relay, configuration):
    - The MyFamily option may now be repeated as many times as desired,
      for relays that want to configure large families. Closes ticket
      4998; patch by Daniel Pinto.

  o Minor features (safety):
    - Add an explicit check to extrainfo_parse_entry_from_string() for
      NULL inputs. We don't believe this can actually happen, but it may
      help silence a warning from the Clang analyzer. Closes
      ticket 21496.

  o Minor features (testing):
    - Add a "--disable-memory-sentinels" feature to help with fuzzing.
      When Tor is compiled with this option, we disable a number of
      redundant memory-safety failsafes that are intended to stop bugs
      from becoming security issues. This makes it easier to hunt for
      bugs that would be security issues without the failsafes turned
      on. Closes ticket 21439.
    - Add a general event-tracing instrumentation support to Tor. This
      subsystem will enable developers and researchers to add fine-
      grained instrumentation to their Tor instances, for use when
      examining Tor network performance issues. There are no trace
      events yet, and event-tracing is off by default unless enabled at
      compile time. Implements ticket 13802.
    - Improve our version parsing tests: add tests for typical version
      components, add tests for invalid versions, including numeric
      range and non-numeric prefixes. Unit tests 21278, 21450, and
      21507. Partially implements 21470.

  o Minor bugfixes (bandwidth accounting):
    - Roll over monthly accounting at the configured hour and minute,
      rather than always at 00:00. Fixes bug 22245; bugfix on 0.0.9rc1.
      Found by Andrey Karpov with PVS-Studio.

  o Minor bugfixes (code correctness):
    - Accurately identify client connections by their lack of peer
      authentication. This means that we bail out earlier if asked to
      extend to a client. Follow-up to 21407. Fixes bug 21406; bugfix

  o Minor bugfixes (configuration):
    - Do not crash when starting with LearnCircuitBuildTimeout 0. Fixes
      bug 22252; bugfix on

  o Minor bugfixes (connection lifespan):
    - Allow more control over how long TLS connections are kept open:
      unify CircuitIdleTimeout and PredictedPortsRelevanceTime into a
      single option called CircuitsAvailableTimeout. Also, allow the
      consensus to control the default values for both this preference
      and the lifespan of relay-to-relay connections. Fixes bug 17592;
      bugfix on
    - Increase the initial circuit build timeout testing frequency, to
      help ensure that ReducedConnectionPadding clients finish learning
      a timeout before their orconn would expire. The initial testing
      rate was set back in the days of TAP and before the Tor Browser
      updater, when we had to be much more careful about new clients
      making lots of circuits. With this change, a circuit build timeout
      is learned in about 15-20 minutes, instead of 100-120 minutes.

  o Minor bugfixes (controller):
    - GETINFO onions/current and onions/detached no longer respond with
      551 on empty lists. Fixes bug 21329; bugfix on
    - Trigger HS descriptor events on the control port when the client
      fails to pick a hidden service directory for a hidden service.
      This can happen if all the hidden service directories are in
      ExcludeNodes, or they have all been queried within the last 15
      minutes. Fixes bug 22042; bugfix on

  o Minor bugfixes (directory authority):
    - When rejecting a router descriptor for running an obsolete version
      of Tor without ntor support, warn about the obsolete tor version,
      not the missing ntor key. Fixes bug 20270; bugfix on
    - Prevent the shared randomness subsystem from asserting when
      initialized by a bridge authority with an incomplete configuration
      file. Fixes bug 21586; bugfix on

  o Minor bugfixes (exit-side DNS):
    - Fix an untriggerable assertion that checked the output of a
      libevent DNS error, so that the assertion actually behaves as
      expected. Fixes bug 22244; bugfix on Found by Andrey
      Karpov using PVS-Studio.

  o Minor bugfixes (fallback directories):
    - Make the usage example in updateFallbackDirs.py actually work, and
      explain what it does. Fixes bug 22270; bugfix on
    - Decrease the guard flag average required to be a fallback. This
      allows us to keep relays that have their guard flag removed when
      they restart. Fixes bug 20913; bugfix on
    - Decrease the minimum number of fallbacks to 100. Fixes bug 20913;
      bugfix on
    - Make sure fallback directory mirrors have the same address, port,
      and relay identity key for at least 30 days before they are
      selected. Fixes bug 20913; bugfix on

  o Minor bugfixes (hidden services):
    - Stop printing a cryptic warning when a hidden service gets a
      request to connect to a virtual port that it hasn't configured.
      Fixes bug 16706; bugfix on
    - Simplify hidden service descriptor creation by using an existing
      flag to check if an introduction point is established. Fixes bug
      21599; bugfix on

  o Minor bugfixes (memory leak):
    - Fix a small memory leak at exit from the backtrace handler code.
      Fixes bug 21788; bugfix on Patch from Daniel Pinto.

  o Minor bugfixes (protocol, logging):
    - Downgrade a log statement about unexpected relay cells from "bug"
      to "protocol warning", because there is at least one use case
      where it can be triggered by a buggy tor implementation. Fixes bug
      21293; bugfix on

  o Minor bugfixes (testing):
    - Use unbuffered I/O for utility functions around the
      process_handle_t type. This fixes unit test failures reported on
      OpenBSD and FreeBSD. Fixes bug 21654; bugfix on
    - Make display of captured unit test log messages consistent. Fixes
      bug 21510; bugfix on
    - Make test-network.sh always call chutney's test-network.sh.
      Previously, this only worked on systems which had bash installed,
      due to some bash-specific code in the script. Fixes bug 19699;
      bugfix on Follow-up to ticket 21581.

  o Minor bugfixes (voting consistency):
    - Reject version numbers with non-numeric prefixes (such as +, -, or
      whitespace). Disallowing whitespace prevents differential version
      parsing between POSIX-based and Windows platforms. Fixes bug 21507
      and part of 21508; bugfix on 0.0.8pre1.

  o Minor bugfixes (windows, relay):
    - Resolve "Failure from drain_fd: No error" warnings on Windows
      relays. Fixes bug 21540; bugfix on

  o Code simplification and refactoring:
    - Break up the 630-line function connection_dir_client_reached_eof()
      into a dozen smaller functions. This change should help
      maintainability and readability of the client directory code.
    - Isolate our use of the openssl headers so that they are only
      included from our crypto wrapper modules, and from tests that
      examine those modules' internals. Closes ticket 21841.
    - Simplify our API to launch directory requests, making it more
      extensible and less error-prone. Now it's easier to add extra
      headers to directory requests. Closes ticket 21646.
    - Our base64 decoding functions no longer overestimate the output
      space that they need when parsing unpadded inputs. Closes
      ticket 17868.
    - Remove unused "ROUTER_ADDED_NOTIFY_GENERATOR" internal value.
      Resolves ticket 22213.
    - The logic that directory caches use to spool request to clients,
      serving them one part at a time so as not to allocate too much
      memory, has been refactored for consistency. Previously there was
      a separate spooling implementation per type of spoolable data. Now
      there is one common spooling implementation, with extensible data
      types. Closes ticket 21651.
    - Tor's compression module now supports multiple backends. Part of
      the implementation for proposal 278; closes ticket 21663.

  o Documentation:
    - Clarify the behavior of the KeepAliveIsolateSOCKSAuth sub-option.
      Closes ticket 21873.
    - Correct documentation about the default DataDirectory value.
      Closes ticket 21151.
    - Document the default behavior of NumEntryGuards and
      NumDirectoryGuards correctly. Fixes bug 21715; bugfix
    - Document key=value pluggable transport arguments for Bridge lines
      in torrc. Fixes bug 20341; bugfix on
    - Note that bandwidth-limiting options don't affect TCP headers or
      DNS. Closes ticket 17170.

  o Removed features (configuration options, all in ticket 22060):
    - These configuration options are now marked Obsolete, and no longer
      have any effect: AllowInvalidNodes, AllowSingleHopCircuits,
      AllowSingleHopExits, ExcludeSingleHopRelays, FastFirstHopPK,
      TLSECGroup, WarnUnsafeSocks. They were first marked as deprecated
      in and have now been removed. The previous default
      behavior is now always chosen; the previous (less secure) non-
      default behavior is now unavailable.
    - CloseHSClientCircuitsImmediatelyOnTimeout and
      CloseHSServiceRendCircuitsImmediatelyOnTimeout were deprecated in and now have been removed. HS circuits never close
      on circuit build timeout; they have a longer timeout period.
    - {Control,DNS,Dir,Socks,Trans,NATD,OR}ListenAddress were deprecated
      in and now have been removed. Use the ORPort option
      (and others) to configure listen-only and advertise-only addresses.

  o Removed features (tools):
    - We've removed the tor-checkkey tool from src/tools. Long ago, we
      used it to help people detect RSA keys that were generated by
      versions of Debian affected by CVE-2008-0166. But those keys have
      been out of circulation for ages, and this tool is no longer
      required. Closes ticket 21842.
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