Prop210: Add schedules for simultaneous client consensus downloads

Prop210: Add attempt-based connection schedules

Existing tor schedules increment the schedule position on failure,
then retry the connection after the scheduled time.

To make multiple simultaneous connections, we need to increment the
schedule position when making each attempt, then retry a (potentially
simultaneous) connection after the scheduled time.

(Also change find_dl_schedule_and_len to find_dl_schedule, as it no
longer takes or returns len.)

Prop210: Add multiple simultaneous consensus downloads for clients

Make connections on TestingClientBootstrapConsensus*DownloadSchedule,
incrementing the schedule each time the client attempts to connect.

Check if the number of downloads is less than
TestingClientBootstrapConsensusMaxInProgressTries before trying any
more connections.

doc/tor.1.txt

@@ -2281,10 +2281,18 @@ The following options are used for running a testing Tor network.
        TestingClientDownloadSchedule 0, 0, 5, 10, 15, 20, 30, 60
        TestingServerConsensusDownloadSchedule 0, 0, 5, 10, 15, 20, 30, 60
        TestingClientConsensusDownloadSchedule 0, 0, 5, 10, 15, 20, 30, 60
+       TestingClientBootstrapConsensusAuthorityDownloadSchedule 0, 2,
+           4 (for 40 seconds), 8, 16, 32, 60
+       TestingClientBootstrapConsensusFallbackDownloadSchedule 0, 1,
+           4 (for 40 seconds), 8, 16, 32, 60
+       TestingClientBootstrapConsensusAuthorityOnlyDownloadSchedule 0, 1,
+           4 (for 40 seconds), 8, 16, 32, 60
        TestingBridgeDownloadSchedule 60, 30, 30, 60
        TestingClientMaxIntervalWithoutRequest 5 seconds
        TestingDirConnectionMaxStall 30 seconds
        TestingConsensusMaxDownloadTries 80
+       TestingClientBootstrapConsensusMaxDownloadTries 80
+       TestingClientBootstrapConsensusAuthorityOnlyMaxDownloadTries 80
        TestingDescriptorMaxDownloadTries 80
        TestingMicrodescMaxDownloadTries 80
        TestingCertMaxDownloadTries 80
@@ -2345,6 +2353,36 @@ The following options are used for running a testing Tor network.
     requires that **TestingTorNetwork** is set. (Default: 0, 0, 60, 300, 600,
     1800, 3600, 3600, 3600, 10800, 21600, 43200)
 
+[[TestingClientBootstrapConsensusAuthorityDownloadSchedule]] **TestingClientBootstrapConsensusAuthorityDownloadSchedule** __N__,__N__,__...__::
+    Schedule for when clients should download consensuses from authorities if
+    they are bootstrapping (that is, they don't have a usable, reasonably live
+    consensus). Only used by clients fetching from a list of fallback
+    directory mirrors. This schedule is advanced by (potentially concurrent)
+    connection attempts, unlike other schedules, which are advanced by
+    connection failures. Changing this schedule requires that
+    **TestingTorNetwork** is set. (Default: 10, 11, 3600, 10800, 25200, 54000,
+    111600, 262800)
+
+[[TestingClientBootstrapConsensusFallbackDownloadSchedule]] **TestingClientBootstrapConsensusFallbackDownloadSchedule** __N__,__N__,__...__::
+    Schedule for when clients should download consensuses from fallback
+    directory mirrors if they are bootstrapping (that is, they don't have a
+    usable, reasonably live consensus). Only used by clients fetching from a
+    list of fallback directory mirrors.  This schedule is advanced by
+    (potentially concurrent) connection attempts, unlike other schedules, which
+    are advanced by connection failures. Changing this schedule requires that
+    **TestingTorNetwork** is set. (Default: 0, 1, 4, 11, 3600, 10800, 25200,
+    54000, 111600, 262800)
+
+[[TestingClientBootstrapConsensusAuthorityOnlyDownloadSchedule]] **TestingClientBootstrapConsensusAuthorityOnlyDownloadSchedule** __N__,__N__,__...__::
+    Schedule for when clients should download consensuses from authorities if
+    they are bootstrapping (that is, they don't have a usable, reasonably live
+    consensus). Only used by clients which don't have or won't fetch from a
+    list of fallback directory mirrors. This schedule is advanced by
+    (potentially concurrent) connection attempts, unlike other schedules,
+    which are advanced by connection failures. Changing this schedule requires
+    that **TestingTorNetwork** is set. (Default: 0, 3, 7, 3600, 10800, 25200,
+    54000, 111600, 262800)
+
 [[TestingBridgeDownloadSchedule]] **TestingBridgeDownloadSchedule** __N__,__N__,__...__::
     Schedule for when clients should download bridge descriptors. Changing this
     requires that **TestingTorNetwork** is set. (Default: 3600, 900, 900, 3600)
@@ -2361,9 +2399,24 @@ The following options are used for running a testing Tor network.
     5 minutes)
 
 [[TestingConsensusMaxDownloadTries]] **TestingConsensusMaxDownloadTries** __NUM__::
-    Try this often to download a consensus before giving up. Changing
+    Try this many times to download a consensus before giving up. Changing
     this requires that **TestingTorNetwork** is set. (Default: 8)
 
+[[TestingClientBootstrapConsensusMaxDownloadTries]] **TestingClientBootstrapConsensusMaxDownloadTries** __NUM__::
+    Try this many times to download a consensus while bootstrapping using
+    fallback directory mirrors before giving up. Changing this requires that
+    **TestingTorNetwork** is set. (Default: 7)
+
+[[TestingClientBootstrapConsensusMaxDownloadTries]] **TestingClientBootstrapConsensusMaxDownloadTries** __NUM__::
+    Try this many times to download a consensus while bootstrapping using
+    only authorities before giving up. Changing this requires that
+    **TestingTorNetwork** is set. (Default: 4)
+
+[[TestingClientBootstrapConsensusMaxInProgressTries]] **TestingClientBootstrapConsensusMaxInProgressTries** __NUM__::
+    Try this many simultaneous connections to download a consensus before
+    waiting for one to complete, timeout, or error out. Changing this
+    requires that **TestingTorNetwork** is set. (Default: 4)
+
 [[TestingDescriptorMaxDownloadTries]] **TestingDescriptorMaxDownloadTries** __NUM__::
     Try this often to download a server descriptor before giving up.
     Changing this requires that **TestingTorNetwork** is set. (Default: 8)