Merge bitcoin/bitcoin#24830: init: Allow -proxy="" setting values

1d4122dfefcb0a33c3d5bf7bbe2c7cd7e09d3764 init: Allow -proxy="" setting values (Ryan Ofsky)

Pull request description:

  This drops the `No proxy server specified. Use -proxy=<ip> or -proxy=<ip:port>` error when a empty `-proxy=` command line argument, `bitcoin.conf` value, or `settings.json` value is specified, and just makes bitcoin connect and listen normally in these cases.

  The error was originally added in https://github.com/bitcoin/bitcoin/pull/20003 to prevent a bare `-proxy` command line argument with no assignment from clearing proxy settings. But it was implemented in an overbroad way breaking empty `-proxy=` assignments as well.

  The motivation for this change is to prevent a GUI bug that happens with https://github.com/bitcoin/bitcoin/pull/15936, reported in https://github.com/bitcoin/bitcoin/pull/15936#pullrequestreview-937685759 by vasild, that happens after a proxy setting is enabled and disabled in the GUI. But this change also makes sense on its own to remove a potentially confusing error message.

ACKs for top commit:
  hebasto:
    re-ACK 1d4122dfefcb0a33c3d5bf7bbe2c7cd7e09d3764, only rebased since my recent [review](https://github.com/bitcoin/bitcoin/pull/24830#pullrequestreview-941255672).

Tree-SHA512: 753adfce199ed078a6cd9e0ea78e76c0b14070f8fcfe2a4632cd0c6dfe6b4e135ddffbe11a97e5e30520ea9e5bda00bad1493cbaef74cf425aa8613249167f53

1 files changed, 1 insertions, 5 deletions

diff --git a/src/init.cpp b/src/init.cpp
index f06b5bd0d0..e65af7e7ba 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -471,7 +471,7 @@ void SetupServerArgs(ArgsManager& argsman)
     // TODO: remove the sentence "Nodes not using ... incoming connections." once the changes from
     // https://github.com/bitcoin/bitcoin/pull/23542 have become widespread.
     argsman.AddArg("-port=<port>", strprintf("Listen for connections on <port>. Nodes not using the default ports (default: %u, testnet: %u, signet: %u, regtest: %u) are unlikely to get incoming connections. Not relevant for I2P (see doc/i2p.md).", defaultChainParams->GetDefaultPort(), testnetChainParams->GetDefaultPort(), signetChainParams->GetDefaultPort(), regtestChainParams->GetDefaultPort()), ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY, OptionsCategory::CONNECTION);
-    argsman.AddArg("-proxy=<ip:port>", "Connect through SOCKS5 proxy, set -noproxy to disable (default: disabled)", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
+    argsman.AddArg("-proxy=<ip:port>", "Connect through SOCKS5 proxy, set -noproxy to disable (default: disabled)", ArgsManager::ALLOW_ANY | ArgsManager::DISALLOW_ELISION, OptionsCategory::CONNECTION);
     argsman.AddArg("-proxyrandomize", strprintf("Randomize credentials for every proxy connection. This enables Tor stream isolation (default: %u)", DEFAULT_PROXYRANDOMIZE), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-seednode=<ip>", "Connect to a node to retrieve peer addresses, and disconnect. This option can be specified multiple times to connect to multiple nodes.", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-networkactive", "Enable all P2P network activity (default: 1). Can be changed by the setnetworkactive RPC command", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
@@ -1029,10 +1029,6 @@ bool AppInitParameterInteraction(const ArgsManager& args, bool use_syscall_sandb
 
     nMaxTipAge = args.GetIntArg("-maxtipage", DEFAULT_MAX_TIP_AGE);
 
-    if (args.IsArgSet("-proxy") && args.GetArg("-proxy", "").empty()) {
-        return InitError(_("No proxy server specified. Use -proxy=<ip> or -proxy=<ip:port>."));
-    }
-
     if (args.GetBoolArg("-reindex-chainstate", false)) {
         // indexes that must be deactivated to prevent index corruption, see #24630
         if (args.GetBoolArg("-coinstatsindex", DEFAULT_COINSTATSINDEX)) {