Merge remote-tracking branch 'teor/feature17327-v4'

diff --cc doc/tor.1.txt
index 562fed931b5730d2f86c678acefa08c35bd1b123,3ef5674d2bee6ca2c9f133950fea7dc3997b6765..f173a97aa3cdc4f3141226bd3072d713430a9c1a
--- 1/doc/tor.1.txt
--- 2/doc/tor.1.txt
+++ b/doc/tor.1.txt
@@@ -358,20 -358,10 +358,20 @@@ GENERAL OPTION
      DataDirectory. If the option is set to 1, make the DataDirectory readable
      by the default GID. (Default: 0)
  
- [[FallbackDir]] **FallbackDir** __address__:__port__ orport=__port__ id=__fingerprint__ [weight=__num__]::
+ [[FallbackDir]] **FallbackDir** __address__:__port__ orport=__port__ id=__fingerprint__ [weight=__num__] [ipv6=__address__:__orport__]::
      When we're unable to connect to any directory cache for directory info
 -    (usually because we don't know about any yet) we try a FallbackDir.
 -    By default, the directory authorities are also FallbackDirs.
 +    (usually because we don't know about any yet) we try a directory authority.
 +    Clients also simultaneously try a FallbackDir, to avoid hangs on client
 +    startup if a directory authority is down. Clients retry FallbackDirs more
 +    often than directory authorities, to reduce the load on the directory
 +    authorities.
 +    By default, the directory authorities are also FallbackDirs. Specifying a
 +    FallbackDir replaces Tor's default hard-coded FallbackDirs (if any).
 +
 +[[UseDefaultFallbackDirs]] **UseDefaultFallbackDirs** **0**|**1**::
 +    Use Tor's default hard-coded FallbackDirs (if any). (When a
 +    FallbackDir line is present, it replaces the hard-coded FallbackDirs,
 +    regardless of the value of UseDefaultFallbackDirs.) (Default: 1)
  
  [[DirAuthority]] **DirAuthority** [__nickname__] [**flags**] __address__:__port__ __fingerprint__::
      Use a nonstandard authoritative directory server at the provided address

diff --cc src/or/config.c
Simple merge

diff --cc src/or/or.h
Simple merge

diff --cc src/or/routerlist.c
Simple merge

diff --cc src/or/routerlist.h
Simple merge

diff --cc src/test/test_config.c
index 1d25f8693f330b8db5103968ec91ad380b626a70,580dae4167f4f099cffbb105fb88f1f60203dcc1..0137d1c49a09a76b15c476b89fda370b2848d2c8
--- 1/src/test/test_config.c
--- 2/src/test/test_config.c
+++ b/src/test/test_config.c
@@@ -3326,8 -3383,12 +3496,13 @@@ test_config_use_multiple_directories(vo
    { #name, test_config_ ## name, flags, NULL, NULL }
  
  struct testcase_t config_tests[] = {
+   CONFIG_TEST(adding_trusted_dir_server, TT_FORK),
+   CONFIG_TEST(adding_fallback_dir_server, TT_FORK),
+   CONFIG_TEST(parsing_trusted_dir_server, 0),
+   CONFIG_TEST(parsing_fallback_dir_server, 0),
+   CONFIG_TEST(adding_default_trusted_dir_servers, TT_FORK),
    CONFIG_TEST(adding_dir_servers, TT_FORK),
 +  CONFIG_TEST(default_dir_servers, TT_FORK),
    CONFIG_TEST(resolve_my_address, TT_FORK),
    CONFIG_TEST(addressmap, 0),
    CONFIG_TEST(parse_bridge_line, 0),