Log Message:
Updated tor to 0.3.0.6.

Changes in version 0.3.0.6 - 2017-04-26
  Tor 0.3.0.6 is the first stable release of the Tor 0.3.0 series.

  With the 0.3.0 series, clients and relays now use Ed25519 keys to
  authenticate their link connections to relays, rather than the old
  RSA1024 keys that they used before. (Circuit crypto has been
  Curve25519-authenticated since 0.2.4.8-alpha.) We have also replaced
  the guard selection and replacement algorithm to behave more robustly
  in the presence of unreliable networks, and to resist guard-
  capture attacks.

  This series also includes numerous other small features and bugfixes,
  along with more groundwork for the upcoming hidden-services revamp.

  Per our stable release policy, we plan to support the Tor 0.3.0
  release series for at least the next nine months, or for three months
  after the first stable release of the 0.3.1 series: whichever is
  longer. If you need a release with long-term support, we recommend
  that you stay with the 0.2.9 series.

  Below are the changes since 0.2.9.10. For a list of only the changes
  since 0.3.0.5-rc, see the ChangeLog file.

  o Major features (directory authority, security):
    - The default for AuthDirPinKeys is now 1: directory authorities
      will reject relays where the RSA identity key matches a previously
      seen value, but the Ed25519 key has changed. Closes ticket 18319.

  o Major features (guard selection algorithm):
    - Tor's guard selection algorithm has been redesigned from the
      ground up, to better support unreliable networks and restrictive
      sets of entry nodes, and to better resist guard-capture attacks by
      hostile local networks. Implements proposal 271; closes
      ticket 19877.

  o Major features (next-generation hidden services):
    - Relays can now handle v3 ESTABLISH_INTRO cells as specified by
      prop224 aka "Next Generation Hidden Services". Service and clients
      don't use this functionality yet. Closes ticket 19043. Based on
      initial code by Alec Heifetz.
    - Relays now support the HSDir version 3 protocol, so that they can
      can store and serve v3 descriptors. This is part of the next-
      generation onion service work detailled in proposal 224. Closes
      ticket 17238.

  o Major features (protocol, ed25519 identity keys):
    - Clients now support including Ed25519 identity keys in the EXTEND2
      cells they generate. By default, this is controlled by a consensus
      parameter, currently disabled. You can turn this feature on for
      testing by setting ExtendByEd25519ID in your configuration. This
      might make your traffic appear different than the traffic
      generated by other users, however. Implements part of ticket
      15056; part of proposal 220.
    - Relays now understand requests to extend to other relays by their
      Ed25519 identity keys. When an Ed25519 identity key is included in
      an EXTEND2 cell, the relay will only extend the circuit if the
      other relay can prove ownership of that identity. Implements part
      of ticket 15056; part of proposal 220.
    - Relays now use Ed25519 to prove their Ed25519 identities and to
      one another, and to clients. This algorithm is faster and more
      secure than the RSA-based handshake we've been doing until now.
      Implements the second big part of proposal 220; Closes
      ticket 15055.

  o Major features (security):
    - Change the algorithm used to decide DNS TTLs on client and server
      side, to better resist DNS-based correlation attacks like the
      DefecTor attack of Greschbach, Pulls, Roberts, Winter, and
      Feamster. Now relays only return one of two possible DNS TTL
      values, and clients are willing to believe DNS TTL values up to 3
      hours long. Closes ticket 19769.

  o Major bugfixes (client, onion service, also in 0.2.9.9):
    - Fix a client-side onion service reachability bug, where multiple
      socks requests to an onion service (or a single slow request)
      could cause us to mistakenly mark some of the service's
      introduction points as failed, and we cache that failure so
      eventually we run out and can't reach the service. Also resolves a
      mysterious "Remote server sent bogus reason code 65021" log
      warning. The bug was introduced in ticket 17218, where we tried to
      remember the circuit end reason as a uint16_t, which mangled
      negative values. Partially fixes bug 21056 and fixes bug 20307;
      bugfix on 0.2.8.1-alpha.

  o Major bugfixes (crash, directory connections):
    - Fix a rare crash when sending a begin cell on a circuit whose
      linked directory connection had already been closed. Fixes bug
      21576; bugfix on 0.2.9.3-alpha. Reported by Alec Muffett.

  o Major bugfixes (directory authority):
    - During voting, when marking a relay as a probable sybil, do not
      clear its BadExit flag: sybils can still be bad in other ways
      too. (We still clear the other flags.) Fixes bug 21108; bugfix
      on 0.2.0.13-alpha.

  o Major bugfixes (DNS):
    - Fix a bug that prevented exit nodes from caching DNS records for
      more than 60 seconds. Fixes bug 19025; bugfix on 0.2.4.7-alpha.

  o Major bugfixes (IPv6 Exits):
    - Stop rejecting all IPv6 traffic on Exits whose exit policy rejects
      any IPv6 addresses. Instead, only reject a port over IPv6 if the
      exit policy rejects that port on more than an IPv6 /16 of
      addresses. This bug was made worse by 17027 in 0.2.8.1-alpha,
      which rejected a relay's own IPv6 address by default. Fixes bug
      21357; bugfix on commit 004f3f4e53 in 0.2.4.7-alpha.

  o Major bugfixes (parsing):
    - Fix an integer underflow bug when comparing malformed Tor
      versions. This bug could crash Tor when built with
      --enable-expensive-hardening, or on Tor 0.2.9.1-alpha through Tor
      0.2.9.8, which were built with -ftrapv by default. In other cases
      it was harmless. Part of TROVE-2017-001. Fixes bug 21278; bugfix
      on 0.0.8pre1. Found by OSS-Fuzz.
    - When parsing a malformed content-length field from an HTTP
      message, do not read off the end of the buffer. This bug was a
      potential remote denial-of-service attack against Tor clients and
      relays. A workaround was released in October 2016, to prevent this
      bug from crashing Tor. This is a fix for the underlying issue,
      which should no longer matter (if you applied the earlier patch).
      Fixes bug 20894; bugfix on 0.2.0.16-alpha. Bug found by fuzzing
      using AFL (http://lcamtuf.coredump.cx/afl/).

  o Major bugfixes (scheduler):
    - Actually compare circuit policies in ewma_cmp_cmux(). This bug
      caused the channel scheduler to behave more or less randomly,
      rather than preferring channels with higher-priority circuits.
      Fixes bug 20459; bugfix on 0.2.6.2-alpha.

  o Major bugfixes (security, also in 0.2.9.9):
    - Downgrade the "-ftrapv" option from "always on" to \ 
"only on when
      --enable-expensive-hardening is provided." This hardening option,
      like others, can turn survivable bugs into crashes--and having it
      on by default made a (relatively harmless) integer overflow bug
      into a denial-of-service bug. Fixes bug 21278 (TROVE-2017-001);
      bugfix on 0.2.9.1-alpha.

  o Minor feature (client):
    - Enable IPv6 traffic on the SocksPort by default. To disable this,
      a user will have to specify "NoIPv6Traffic". Closes ticket 21269.

  o Minor feature (fallback scripts):
    - Add a check_existing mode to updateFallbackDirs.py, which checks
      if fallbacks in the hard-coded list are working. Closes ticket
      20174. Patch by haxxpop.

  o Minor feature (protocol versioning):
    - Add new protocol version for proposal 224. HSIntro now advertises
      version "3-4" and HSDir version "1-2". Fixes ticket 20656.

  o Minor features (ciphersuite selection):
    - Allow relays to accept a wider range of ciphersuites, including
      chacha20-poly1305 and AES-CCM. Closes the other part of 15426.
    - Clients now advertise a list of ciphersuites closer to the ones
      preferred by Firefox. Closes part of ticket 15426.

  o Minor features (controller):
    - Add "GETINFO sr/current" and "GETINFO sr/previous" \ 
keys, to expose
      shared-random values to the controller. Closes ticket 19925.
    - When HSFETCH arguments cannot be parsed, say "Invalid argument"
      rather than "unrecognized." Closes ticket 20389; patch from
      Ivan Markin.

  o Minor features (controller, configuration):
    - Each of the *Port options, such as SocksPort, ORPort, ControlPort,
      and so on, now comes with a __*Port variant that will not be saved
      to the torrc file by the controller's SAVECONF command. This
      change allows TorBrowser to set up a single-use domain socket for
      each time it launches Tor. Closes ticket 20956.
    - The GETCONF command can now query options that may only be
      meaningful in context-sensitive lists. This allows the controller
      to query the mixed SocksPort/__SocksPort style options introduced
      in feature 20956. Implements ticket 21300.

  o Minor features (diagnostic, directory client):
    - Warn when we find an unexpected inconsistency in directory
      download status objects. Prevents some negative consequences of
      bug 20593.

  o Minor features (directory authorities):
    - Directory authorities now reject descriptors that claim to be
      malformed versions of Tor. Helps prevent exploitation of
      bug 21278.
    - Reject version numbers with components that exceed INT32_MAX.
      Otherwise 32-bit and 64-bit platforms would behave inconsistently.
      Fixes bug 21450; bugfix on 0.0.8pre1.

  o Minor features (directory authority):
    - Add a new authority-only AuthDirTestEd25519LinkKeys option (on by
      default) to control whether authorities should try to probe relays
      by their Ed25519 link keys. This option will go away in a few
      releases--unless we encounter major trouble in our ed25519 link
      protocol rollout, in which case it will serve as a safety option.

  o Minor features (directory cache):
    - Relays and bridges will now refuse to serve the consensus they
      have if they know it is too old for a client to use. Closes
      ticket 20511.

  o Minor features (ed25519 link handshake):
    - Advertise support for the ed25519 link handshake using the
      subprotocol-versions mechanism, so that clients can tell which
      relays can identity themselves by Ed25519 ID. Closes ticket 20552.

  o Minor features (entry guards):
    - Add UseEntryGuards to TEST_OPTIONS_DEFAULT_VALUES in order to not
      break regression tests.
    - Require UseEntryGuards when UseBridges is set, in order to make
      sure bridges aren't bypassed. Resolves ticket 20502.

  o Minor features (fallback directories):
    - Allow 3 fallback relays per operator, which is safe now that we
      are choosing 200 fallback relays. Closes ticket 20912.
    - Annotate updateFallbackDirs.py with the bandwidth and consensus
      weight for each candidate fallback. Closes ticket 20878.
    - Display the relay fingerprint when downloading consensuses from
      fallbacks. Closes ticket 20908.
    - Exclude relays affected by bug 20499 from the fallback list.
      Exclude relays from the fallback list if they are running versions
      known to be affected by bug 20499, or if in our tests they deliver
      a stale consensus (i.e. one that expired more than 24 hours ago).
      Closes ticket 20539.
    - Make it easier to change the output sort order of fallbacks.
      Closes ticket 20822.
    - Reduce the minimum fallback bandwidth to 1 MByte/s. Part of
      ticket 18828.
    - Require fallback directories to have the same address and port for
      7 days (now that we have enough relays with this stability).
      Relays whose OnionOO stability timer is reset on restart by bug
      18050 should upgrade to Tor 0.2.8.7 or later, which has a fix for
      this issue. Closes ticket 20880; maintains short-term fix
      in 0.2.8.2-alpha.
    - Require fallbacks to have flags for 90% of the time (weighted
      decaying average), rather than 95%. This allows at least 73% of
      clients to bootstrap in the first 5 seconds without contacting an
      authority. Part of ticket 18828.
    - Select 200 fallback directories for each release. Closes
      ticket 20881.

  o Minor features (fingerprinting resistence, authentication):
    - Extend the length of RSA keys used for TLS link authentication to
      2048 bits. (These weren't used for forward secrecy; for forward
      secrecy, we used P256.) Closes ticket 13752.

  o Minor features (geoip):
    - Update geoip and geoip6 to the April 4 2017 Maxmind GeoLite2
      Country database.

  o Minor features (geoip, also in 0.2.9.9):
    - Update geoip and geoip6 to the January 4 2017 Maxmind GeoLite2
      Country database.

  o Minor features (infrastructure):
    - Implement smartlist_add_strdup() function. Replaces the use of
      smartlist_add(sl, tor_strdup(str)). Closes ticket 20048.

  o Minor features (linting):
    - Enhance the changes file linter to warn on Tor versions that are
      prefixed with "tor-". Closes ticket 21096.

  o Minor features (logging):
    - In several places, describe unset ed25519 keys as "<unset>",
      rather than the scary "AAAAAAAA...AAA". Closes ticket 21037.

  o Minor features (portability, compilation):
    - Autoconf now checks to determine if OpenSSL structures are opaque,
      instead of explicitly checking for OpenSSL version numbers. Part
      of ticket 21359.
    - Support building with recent LibreSSL code that uses opaque
      structures. Closes ticket 21359.

  o Minor features (relay):
    - We now allow separation of exit and relay traffic to different
      source IP addresses, using the OutboundBindAddressExit and
      OutboundBindAddressOR options respectively. Closes ticket 17975.
      Written by Michael Sonntag.

  o Minor features (reliability, crash):
    - Try better to detect problems in buffers where they might grow (or
      think they have grown) over 2 GB in size. Diagnostic for
      bug 21369.

  o Minor features (testing):
    - During 'make test-network-all', if tor logs any warnings, ask
      chutney to output them. Requires a recent version of chutney with
      the 21572 patch. Implements 21570.

  o Minor bugfix (control protocol):
    - The reply to a "GETINFO config/names" request via the control
      protocol now spells the type "Dependent" correctly. This is a
      breaking change in the control protocol. (The field seems to be
      ignored by the most common known controllers.) Fixes bug 18146;
      bugfix on 0.1.1.4-alpha.
    - The GETINFO extra-info/digest/<digest> command was broken because
      of a wrong base16 decode return value check, introduced when
      refactoring that API. Fixes bug 22034; bugfix on 0.2.9.1-alpha.

  o Minor bugfix (logging):
    - Don't recommend the use of Tor2web in non-anonymous mode.
      Recommending Tor2web is a bad idea because the client loses all
      anonymity. Tor2web should only be used in specific cases by users
      who *know* and understand the issues. Fixes bug 21294; bugfix
      on 0.2.9.3-alpha.

  o Minor bugfixes (bug resilience):
    - Fix an unreachable size_t overflow in base64_decode(). Fixes bug
      19222; bugfix on 0.2.0.9-alpha. Found by Guido Vranken; fixed by
      Hans Jerry Illikainen.

  o Minor bugfixes (build):
    - Replace obsolete Autoconf macros with their modern equivalent and
      prevent similar issues in the future. Fixes bug 20990; bugfix
      on 0.1.0.1-rc.

  o Minor bugfixes (certificate expiration time):
    - Avoid using link certificates that don't become valid till some
      time in the future. Fixes bug 21420; bugfix on 0.2.4.11-alpha

  o Minor bugfixes (client):
    - Always recover from failures in extend_info_from_node(), in an
      attempt to prevent any recurrence of bug 21242. Fixes bug 21372;
      bugfix on 0.2.3.1-alpha.
    - When clients that use bridges start up with a cached consensus on
      disk, they were ignoring it and downloading a new one. Now they
      use the cached one. Fixes bug 20269; bugfix on 0.2.3.12-alpha.

  o Minor bugfixes (code correctness):
    - Repair a couple of (unreachable or harmless) cases of the risky
      comparison-by-subtraction pattern that caused bug 21278.

  o Minor bugfixes (config):
    - Don't assert on startup when trying to get the options list and
      LearnCircuitBuildTimeout is set to 0: we are currently parsing the
      options so of course they aren't ready yet. Fixes bug 21062;
      bugfix on 0.2.9.3-alpha.

  o Minor bugfixes (configuration):
    - Accept non-space whitespace characters after the severity level in
      the `Log` option. Fixes bug 19965; bugfix on 0.2.1.1-alpha.
    - Support "TByte" and "TBytes" units in options given in \ 
bytes.
      "TB", "terabyte(s)", "TBit(s)" and \ 
"terabit(s)" were already
      supported. Fixes bug 20622; bugfix on 0.2.0.14-alpha.

  o Minor bugfixes (configure, autoconf):
    - Rename the configure option --enable-expensive-hardening to
      --enable-fragile-hardening. Expensive hardening makes the tor
      daemon abort when some kinds of issues are detected. Thus, it
      makes tor more at risk of remote crashes but safer against RCE or
      heartbleed bug category. We now try to explain this issue in a
      message from the configure script. Fixes bug 21290; bugfix
      on 0.2.5.4-alpha.

  o Minor bugfixes (consensus weight):
    - Add new consensus method that initializes bw weights to 1 instead
      of 0. This prevents a zero weight from making it all the way to
      the end (happens in small testing networks) and causing an error.
      Fixes bug 14881; bugfix on 0.2.2.17-alpha.

  o Minor bugfixes (crash prevention):
    - Fix an (currently untriggerable, but potentially dangerous) crash
      bug when base32-encoding inputs whose sizes are not a multiple of
      5. Fixes bug 21894; bugfix on 0.2.9.1-alpha.

  o Minor bugfixes (dead code):
    - Remove a redundant check for PidFile changes at runtime in
      options_transition_allowed(): this check is already performed
      regardless of whether the sandbox is active. Fixes bug 21123;
      bugfix on 0.2.5.4-alpha.

  o Minor bugfixes (descriptors):
    - Correctly recognise downloaded full descriptors as valid, even
      when using microdescriptors as circuits. This affects clients with
      FetchUselessDescriptors set, and may affect directory authorities.
      Fixes bug 20839; bugfix on 0.2.3.2-alpha.

  o Minor bugfixes (directory mirrors):
    - Allow relays to use directory mirrors without a DirPort: these
      relays need to be contacted over their ORPorts using a begindir
      connection. Fixes one case of bug 20711; bugfix on 0.2.8.2-alpha.
    - Clarify the message logged when a remote relay is unexpectedly
      missing an ORPort or DirPort: users were confusing this with a
      local port. Fixes another case of bug 20711; bugfix
      on 0.2.8.2-alpha.

  o Minor bugfixes (directory system):
    - Bridges and relays now use microdescriptors (like clients do)
      rather than old-style router descriptors. Now bridges will blend
      in with clients in terms of the circuits they build. Fixes bug
      6769; bugfix on 0.2.3.2-alpha.
    - Download all consensus flavors, descriptors, and authority
      certificates when FetchUselessDescriptors is set, regardless of
      whether tor is a directory cache or not. Fixes bug 20667; bugfix
      on all recent tor versions.

  o Minor bugfixes (documentation):
    - Update the tor manual page to document every option that can not
      be changed while tor is running. Fixes bug 21122.

  o Minor bugfixes (ed25519 certificates):
    - Correctly interpret ed25519 certificates that would expire some
      time after 19 Jan 2038. Fixes bug 20027; bugfix on 0.2.7.2-alpha.

  o Minor bugfixes (fallback directories):
    - Avoid checking fallback candidates' DirPorts if they are down in
      OnionOO. When a relay operator has multiple relays, this
      prioritizes relays that are up over relays that are down. Fixes
      bug 20926; bugfix on 0.2.8.3-alpha.
    - Stop failing when OUTPUT_COMMENTS is True in updateFallbackDirs.py.
      Fixes bug 20877; bugfix on 0.2.8.3-alpha.
    - Stop failing when a relay has no uptime data in
      updateFallbackDirs.py. Fixes bug 20945; bugfix on 0.2.8.1-alpha.

  o Minor bugfixes (hidden service):
    - Clean up the code for expiring intro points with no associated
      circuits. It was causing, rarely, a service with some expiring
      introduction points to not open enough additional introduction
      points. Fixes part of bug 21302; bugfix on 0.2.7.2-alpha.
    - Resolve two possible underflows which could lead to creating and
      closing a lot of introduction point circuits in a non-stop loop.
      Fixes bug 21302; bugfix on 0.2.7.2-alpha.
    - Stop setting the torrc option HiddenServiceStatistics to "0" just
      because we're not a bridge or relay. Instead, we preserve whatever
      value the user set (or didn't set). Fixes bug 21150; bugfix
      on 0.2.6.2-alpha.

  o Minor bugfixes (hidden services):
    - Make hidden services check for failed intro point connections,
      even when they have exceeded their intro point creation limit.
      Fixes bug 21596; bugfix on 0.2.7.2-alpha. Reported by Alec Muffett.
    - Make hidden services with 8 to 10 introduction points check for
      failed circuits immediately after startup. Previously, they would
      wait for 5 minutes before performing their first checks. Fixes bug
      21594; bugfix on 0.2.3.9-alpha. Reported by Alec Muffett.
    - Stop ignoring misconfigured hidden services. Instead, refuse to
      start tor until the misconfigurations have been corrected. Fixes
      bug 20559; bugfix on multiple commits in 0.2.7.1-alpha
      and earlier.

  o Minor bugfixes (IPv6):
    - Make IPv6-using clients try harder to find an IPv6 directory
      server. Fixes bug 20999; bugfix on 0.2.8.2-alpha.
    - When IPv6 addresses have not been downloaded yet (microdesc
      consensus documents don't list relay IPv6 addresses), use hard-
      coded addresses for authorities, fallbacks, and configured
      bridges. Now IPv6-only clients can use microdescriptors. Fixes bug
      20996; bugfix on b167e82 from 19608 in 0.2.8.5-alpha.

  o Minor bugfixes (memory leak at exit):
    - Fix a small harmless memory leak at exit of the previously unused
      RSA->Ed identity cross-certificate. Fixes bug 17779; bugfix
      on 0.2.7.2-alpha.

  o Minor bugfixes (onion services):
    - Allow the number of introduction points to be as low as 0, rather
      than as low as 3. Fixes bug 21033; bugfix on 0.2.7.2-alpha.

  o Minor bugfixes (portability):
    - Use "OpenBSD" compiler macro instead of "OPENBSD" or \ 
"__OpenBSD__".
      It is supported by OpenBSD itself, and also by most OpenBSD
      variants (such as Bitrig). Fixes bug 20980; bugfix
      on 0.1.2.1-alpha.

  o Minor bugfixes (portability, also in 0.2.9.9):
    - Avoid crashing when Tor is built using headers that contain
      CLOCK_MONOTONIC_COARSE, but then tries to run on an older kernel
      without CLOCK_MONOTONIC_COARSE. Fixes bug 21035; bugfix
      on 0.2.9.1-alpha.
    - Fix Libevent detection on platforms without Libevent 1 headers
      installed. Fixes bug 21051; bugfix on 0.2.9.1-alpha.

  o Minor bugfixes (relay):
    - Avoid a double-marked-circuit warning that could happen when we
      receive DESTROY cells under heavy load. Fixes bug 20059; bugfix
      on 0.1.0.1-rc.
    - Honor DataDirectoryGroupReadable when tor is a relay. Previously,
      initializing the keys would reset the DataDirectory to 0700
      instead of 0750 even if DataDirectoryGroupReadable was set to 1.
      Fixes bug 19953; bugfix on 0.0.2pre16. Patch by "redfish".

  o Minor bugfixes (testing):
    - Fix Raspbian build issues related to missing socket errno in
      test_util.c. Fixes bug 21116; bugfix on 0.2.8.2. Patch by "hein".
    - Remove undefined behavior from the backtrace generator by removing
      its signal handler. Fixes bug 21026; bugfix on 0.2.5.2-alpha.
    - Use bash in src/test/test-network.sh. This ensures we reliably
      call chutney's newer tools/test-network.sh when available. Fixes
      bug 21562; bugfix on 0.2.9.1-alpha.

  o Minor bugfixes (tor-resolve):
    - The tor-resolve command line tool now rejects hostnames over 255
      characters in length. Previously, it would silently truncate them,
      which could lead to bugs. Fixes bug 21280; bugfix on 0.0.9pre5.
      Patch by "junglefowl".

  o Minor bugfixes (unit tests):
    - Allow the unit tests to pass even when DNS lookups of bogus
      addresses do not fail as expected. Fixes bug 20862 and 20863;
      bugfix on unit tests introduced in 0.2.8.1-alpha
      through 0.2.9.4-alpha.

  o Minor bugfixes (util):
    - When finishing writing a file to disk, if we were about to replace
      the file with the temporary file created before and we fail to
      replace it, remove the temporary file so it doesn't stay on disk.
      Fixes bug 20646; bugfix on 0.2.0.7-alpha. Patch by fk.

  o Minor bugfixes (Windows services):
    - Be sure to initialize the monotonic time subsystem before using
      it, even when running as an NT service. Fixes bug 21356; bugfix
      on 0.2.9.1-alpha.

  o Minor bugfixes (Windows):
    - Check for getpagesize before using it to mmap files. This fixes
      compilation in some MinGW environments. Fixes bug 20530; bugfix on
      0.1.2.1-alpha. Reported by "ice".

  o Code simplification and refactoring:
    - Abolish all global guard context in entrynodes.c; replace with new
      guard_selection_t structure as preparation for proposal 271.
      Closes ticket 19858.
    - Extract magic numbers in circuituse.c into defined variables.
    - Introduce rend_service_is_ephemeral() that tells if given onion
      service is ephemeral. Replace unclear NULL-checkings for service
      directory with this function. Closes ticket 20526.
    - Refactor circuit_is_available_for_use to remove unnecessary check.
    - Refactor circuit_predict_and_launch_new for readability and
      testability. Closes ticket 18873.
    - Refactor code to manipulate global_origin_circuit_list into
      separate functions. Closes ticket 20921.
    - Refactor large if statement in purpose_needs_anonymity to use
      switch statement instead. Closes part of ticket 20077.
    - Refactor the hashing API to return negative values for errors, as
      is done as throughout the codebase. Closes ticket 20717.
    - Remove data structures that were used to index or_connection
      objects by their RSA identity digests. These structures are fully
      redundant with the similar structures used in the
      channel abstraction.
    - Remove duplicate code in the channel_write_*cell() functions.
      Closes ticket 13827; patch from Pingl.
    - Remove redundant behavior of is_sensitive_dir_purpose, refactor to
      use only purpose_needs_anonymity. Closes part of ticket 20077.
    - The code to generate and parse EXTEND and EXTEND2 cells has been
      replaced with code automatically generated by the
      "trunnel" utility.

  o Documentation (formatting):
    - Clean up formatting of tor.1 man page and HTML doc, where <pre>
      blocks were incorrectly appearing. Closes ticket 20885.

  o Documentation (man page):
    - Clarify many options in tor.1 and add some min/max values for
      HiddenService options. Closes ticket 21058.

  o Documentation:
    - Change '1' to 'weight_scale' in consensus bw weights calculation
      comments, as that is reality. Closes ticket 20273. Patch
      from pastly.
    - Clarify that when ClientRejectInternalAddresses is enabled (which
      is the default), multicast DNS hostnames for machines on the local
      network (of the form *.local) are also rejected. Closes
      ticket 17070.
    - Correct the value for AuthDirGuardBWGuarantee in the manpage, from
      250 KBytes to 2 MBytes. Fixes bug 20435; bugfix on 0.2.5.6-alpha.
    - Include the "TBits" unit in Tor's man page. Fixes part of bug
      20622; bugfix on 0.2.5.1-alpha.
    - Small fixes to the fuzzing documentation. Closes ticket 21472.
    - Stop the man page from incorrectly stating that HiddenServiceDir
      must already exist. Fixes 20486.
    - Update the description of the directory server options in the
      manual page, to clarify that a relay no longer needs to set
      DirPort in order to be a directory cache. Closes ticket 21720.

  o Removed features:
    - The AuthDirMaxServersPerAuthAddr option no longer exists: The same
      limit for relays running on a single IP applies to authority IP
      addresses as well as to non-authority IP addresses. Closes
      ticket 20960.
    - The UseDirectoryGuards torrc option no longer exists: all users
      that use entry guards will also use directory guards. Related to
      proposal 271; implements part of ticket 20831.

  o Testing:
    - Add tests for networkstatus_compute_bw_weights_v10.
    - Add unit tests circuit_predict_and_launch_new.
    - Extract dummy_origin_circuit_new so it can be used by other
      test functions.
    - New unit tests for tor_htonll(). Closes ticket 19563. Patch
      from "overcaffeinated".
    - Perform the coding style checks when running the tests and fail
      when coding style violations are found. Closes ticket 5500.