Add fallback directory mirror helper scripts

Add the generateFallbackDirLine.py script for automatically generating
fallback directory mirror lines from relay fingerprints. No more typos!

Add the lookupFallbackDirContact.py script for automatically looking up
operator contact info from relay fingerprints.

Implements ticket 24706.

changes/ticket24706

@@ -0,0 +1,6 @@
+  o Minor features (fallback directory mirrors):
+    - Add the generateFallbackDirLine.py script for automatically generating
+      fallback directory mirror lines from relay fingerprints. No more typos!
+      Add the lookupFallbackDirContact.py script for automatically looking up
+      operator contact info from relay fingerprints.
+      Implements ticket 24706.

scripts/maint/fallback.blacklist

@@ -3,6 +3,8 @@
 # Format:
 # [ IPv4[:DirPort] ] [ orport=<ORPort> ] [ id=<ID> ] ...
 #   [ ipv6=<IPv6>[:<IPv6 ORPort>] ]
+# or use:
+# scripts/maint/generateFallbackDirLine.py fingerprint ...
 #
 # If a sufficiently specific group of attributes matches, the directory mirror
 # will be excluded: (each group is listed on its own line)

scripts/maint/fallback.whitelist

@@ -2,6 +2,8 @@
 #
 # Format:
 # IPv4:DirPort orport=<ORPort> id=<ID> [ ipv6=<IPv6>:<IPv6 ORPort> ]
+# or use:
+# scripts/maint/generateFallbackDirLine.py fingerprint ...
 #
 # All attributes must match for the directory mirror to be included.
 # If the fallback has an ipv6 key, the whitelist line must also have

scripts/maint/generateFallbackDirLine.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python
+
+# Generate a fallback directory whitelist/blacklist line for every fingerprint
+# passed as an argument.
+#
+# Usage:
+# generateFallbackDirLine.py fingerprint ...
+
+import sys
+
+import stem.descriptor.remote as remote
+
+if len(sys.argv) <= 1:
+  print "Usage: {} fingerprint ...".format(sys.argv[0])
+  sys.exit(-1)
+
+# we need the full consensus, because it has IPv6 ORPorts
+# and we want a fingerprint to router mapping in routers
+#
+# stem returns document_handler='DOCUMENT' as a list of consensuses
+# with one entry
+consensus = remote.get_consensus(document_handler='DOCUMENT').run()[0]
+
+for fingerprint in sys.argv[1:]:
+  if fingerprint in consensus.routers:
+    r = consensus.routers[fingerprint]
+    # Tor clients don't use DirPorts, but old code requires one for fallbacks
+    if r.dir_port is not None:
+      # IPv4:DirPort orport=ORPort id=Fingerprint ipv6=[IPv6]:IPv6ORPort # nick
+      ipv6_or_ap_list = [ apv for apv in r.or_addresses if apv[2] ]
+      ipv6_str = ""
+      if len(ipv6_or_ap_list) > 0:
+        ipv6_or_ap = ipv6_or_ap_list[0]
+        ipv6_str = " ipv6=[{}]:{}".format(ipv6_or_ap[0], ipv6_or_ap[1])
+      print ("{}:{} orport={} id={}{} # {}"
+             .format(r.address, r.dir_port, r.or_port, r.fingerprint,
+                     ipv6_str, r.nickname))
+    else:
+      print "# {} needs a DirPort".format(fingerprint)    
+  else:
+    print "# {} not found in current consensus".format(fingerprint)

scripts/maint/lookupFallbackDirContact.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python
+
+# Lookup fallback directory contact lines for every fingerprint passed as an
+# argument.
+#
+# Usage:
+# lookupFallbackDirContact.py fingerprint ...
+
+import sys
+
+import stem.descriptor.remote as remote
+
+if len(sys.argv) <= 1:
+  print "Usage: {} fingerprint ...".format(sys.argv[0])
+  sys.exit(-1)
+
+# we need descriptors, because the consensus does not have contact infos
+descriptor_list = remote.get_server_descriptors(fingerprints=sys.argv[1:]).run()
+
+descriptor_list_fingerprints = []
+for d in descriptor_list:
+  assert d.fingerprint in sys.argv[1:]
+  descriptor_list_fingerprints.append(d.fingerprint)
+  print "{} {}".format(d.fingerprint, d.contact)
+
+for fingerprint in sys.argv[1:]:
+  if fingerprint not in descriptor_list_fingerprints:
+    print "{} not found in current descriptors".format(fingerprint)