Merge bitcoin/bitcoin#22098: [test, init] DNS seed querying logic

82b6f89819e55af26f5264678e0f93052934bcb3 [style] Small style improvements to DNS parameters (Amiti Uttarwar)
4c89e24f64c1dc1a56a3bcb6b5e2b4fb95e8b29f [test] Test the delay before querying DNS seeds (Amiti Uttarwar)
6395c8ed5689ea72e9a1618f14551775246f6361 [test] Test the interactions between -forcednsseed and -dnsseed (Amiti Uttarwar)
6f6b7df6bdcf863af160c0426e3a22028ca8259a [init] Disallow starting up with conflicting paramters for -dnsseed and -forcednsseed (Amiti Uttarwar)
26d0ffe4f2573e0297c9b0e095c2a0868929b08b [test] Test -forcednsseed causes querying DNS seeds (Amiti Uttarwar)
35851450a928ffacca240fadbf1747a42d5ba256 [test] Test the interactions between -connect and -dnsseed (Amiti Uttarwar)
75c05af361552eeecd100cee8cc40d4cd5a3aa27 [test] Test logic to query DNS seeds with block-relay-only connections (Amiti Uttarwar)
9c0871977839c28636eff975748182888299cd2b [test] Introduce test logic to query DNS seeds (Amiti Uttarwar)

Pull request description:

  This PR adds a DNS seed to the regtest chain params to enable testing the DNS seed querying logic of `CConnman::ThreadDNSAddressSeed` and relevant startup parameters. Adds coverage for the changes in #22013 (and then some).

  The main behavioral change to bitcoind is that this PR disallows starting up with conflicting parameters for `-dnsseed` and `-forcednsseed`.

  The tests include:
  * parameter interactions of different combinations of `-connect`, `-dnsseed` and `-forcednsseed`
  * the delay before querying DNS seeds depending on how many addresses are in the addrman
  * the behavior of `-forcednsseed`
  * skipping DNS querying if we have outbound full relay connections & not block-relay-only connections

  Huge props to mzumsande for identifying the timing technique for testing successful connections before running `ThreadDNSAddressSeed` 🙌🏽

ACKs for top commit:
  mzumsande:
    ACK 82b6f89819e55af26f5264678e0f93052934bcb3
  jnewbery:
    reACK 82b6f89819e55af26f5264678e0f93052934bcb3

Tree-SHA512: 9f0c29bfbf99426727e79c0a25606ae09deab91a92e3c5cee7f84c3ca7503a8ac9ab85a85c51841d40b164ef8c991326070f0b2f41d075fb7985df26f6e95d6d

1 files changed, 6 insertions, 1 deletions

diff --git a/src/init.cpp b/src/init.cpp
index 75394d96b1..aee8b78999 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -426,7 +426,7 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-dnsseed", strprintf("Query for peer addresses via DNS lookup, if low on addresses (default: %u unless -connect used)", DEFAULT_DNSSEED), ArgsManager::ALLOW_BOOL, OptionsCategory::CONNECTION);
     argsman.AddArg("-externalip=<ip>", "Specify your own public address", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-fixedseeds", strprintf("Allow fixed seeds if DNS seeds don't provide peers (default: %u)", DEFAULT_FIXEDSEEDS), ArgsManager::ALLOW_BOOL, OptionsCategory::CONNECTION);
-    argsman.AddArg("-forcednsseed", strprintf("Always query for peer addresses via DNS lookup (default: %u)", DEFAULT_FORCEDNSSEED), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
+    argsman.AddArg("-forcednsseed", strprintf("Always query for peer addresses via DNS lookup (default: %u)", DEFAULT_FORCEDNSSEED), ArgsManager::ALLOW_BOOL, OptionsCategory::CONNECTION);
     argsman.AddArg("-listen", "Accept connections from outside (default: 1 if no -proxy or -connect)", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-listenonion", strprintf("Automatically create Tor onion service (default: %d)", DEFAULT_LISTEN_ONION), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-maxconnections=<n>", strprintf("Maintain at most <n> connections to peers (default: %u). This limit does not apply to connections manually added via -addnode or the addnode RPC, which have a separate limit of %u.", DEFAULT_MAX_PEER_CONNECTIONS, MAX_ADDNODE_CONNECTIONS), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
@@ -848,6 +848,11 @@ bool AppInitParameterInteraction(const ArgsManager& args)
             return InitError(_("Prune mode is incompatible with -coinstatsindex."));
     }
 
+    // If -forcednsseed is set to true, ensure -dnsseed has not been set to false
+    if (args.GetBoolArg("-forcednsseed", DEFAULT_FORCEDNSSEED) && !args.GetBoolArg("-dnsseed", DEFAULT_DNSSEED)){
+        return InitError(_("Cannot set -forcednsseed to true when setting -dnsseed to false."));
+    }
+
     // -bind and -whitebind can't be set when not listening
     size_t nUserBind = args.GetArgs("-bind").size() + args.GetArgs("-whitebind").size();
     if (nUserBind != 0 && !args.GetBoolArg("-listen", DEFAULT_LISTEN)) {