This ticket depends on IPv6 Addresses in legacy/trac#33233, and automatic IPv6 ORPorts in legacy/trac#33246. These tests should be in CI, or they should be repeated after each change. We should support the following combinations of address literals and hostnames: Legacy configurations: 1. (A) No configured Address option 2. (B) Address IPv4 literal 3. (C) Address hostname (use IPv4 and IPv6 DNS addresses) New configurations: 1. (D) Address IPv6 literal 2. (E) Address IPv4 literal / Address IPv6 literal 3. (F) Address hostname / Address hostname (use IPv4 and IPv6 DNS addresses) 4. (G) Address IPv4 literal / Address hostname (only use IPv6 DNS addresses) 5. (H) Address hostname (only use IPv4 DNS addresses) / Address IPv6 literal If we can't find an IPv4 or IPv6 address using the configured Address options: * No IPv4: guess IPv4, and its reachability must succeed. * No IPv6: guess IPv6, publish if reachability succeeds. Combinations A and B are the most common legacy configurations. We want to support the following outcomes for all legacy configurations: * automatic upgrades to guessed and reachable IPv6 addresses, * continuing to operate on IPv4 when the IPv6 address can't be guessed, and * continuing to operate on IPv4 when the IPv6 address has been guessed, but it is unreachable. See proposal 312, section 3.2.1, testing notes: ​https://gitweb.torproject.org/torspec.git/tree/proposals/312-relay-auto-ipv6-addr.txt#n270