Add deriveaddresses RPC util method #14667

Nit: request.params.empty() instead of request.params.size() < 1 :-)

Remove this unused variable :-)

It would be easy enough to add support for picking a specific index from a ranged descriptor, is there a reason you chose to disallow it? Just add a second parameter which specifies the index. EDIT: thinking about it, it would be just as easy to not use a ranged descriptor if we're only using a single key, don't worry.

It seems a weird anti-feature to me. I don't understand why you're adding extra complexity to the function just to prevent a range. If you only want one, you can still do so.

I initially did that to prevent extra complexity, but I've actually encountered a situation where allowing ranges would be very useful. Will change this to return an array.

@Sjors I assume that also includes allowing combo right? Sounds good 👍

@MeshCollider yes, no reason anymore to exclude combo()

This doesn't seem to belong in this file (the file is specific per PR).

listwalletdir was already hijacking that file, so I joined, but I can add a new one.

In which case we could add them to the main file in the first place.

I thought the point of these extra files was mainly to prevent constant rebasing, which seemed mostly a result of different sections interfering, and less when you're just adding one line an existing entry. Though I'm not sure exactly what trips up git.

This file was removed in master. Also, if another patch added a line in the meantime, git(hub) would also report a merge conflict.

Should be plural now :)

I feel like this is unnecessarily complicated, I'd prefer just start and end parameters without the "n" parameter

Nit: This condition would appear when the scriptPubKey does not have a corresponding address (I think this is only currently possible through "raw" or through bare multisig). Perhaps a better error message is possible?

Could also have a test for this error?

If anyone has an example (raw) descriptor that triggers this error, I can add it, and think of a better message.

Try "multi(1,key1,key2)" for some public keys.

Added the bare multisig example and reworded error to "Descriptor does not have a corresponding address".

bad indentation?

indentation.

missing test for this error.

validate range_start < range_end?

Added check and test.

micronit, s/start/begin?

Is it possible to return empty?

Addresses can be an empty UniValue array in theory: UniValue addresses(UniValue::VARR);

I guess not in practice, do you want an error check?

I added an RPC error in case the result is empty. I don't know how to produce that, so there's no test.

Compile failure can be fixed with (large diff due to whitespace fixes)

diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 12d165fff7..e9ff8a8040 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -145,30 +145,29 @@ static UniValue createmultisig(const JSONRPCRequest& request)
 
 UniValue deriveaddresses(const JSONRPCRequest& request)
 {
-    if (request.fHelp || request.params.empty() || request.params.size() > 3)
+    if (request.fHelp || request.params.empty() || request.params.size() > 3) {
         throw std::runtime_error(
-            RPCHelpMan{"deriveaddresses", {
-                "\nDerives one or more addresses corresponding to an output descriptor.\n"
-                "Examples of output descriptors are:\n"
-                "    pkh(<pubkey>)                        P2PKH outputs for the given pubkey\n"
-                "    wpkh(<pubkey>)                       Native segwit P2PKH outputs for the given pubkey\n"
-                "    sh(multi(<n>,<pubkey>,<pubkey>,...)) P2SH-multisig outputs for the given threshold and pubkeys\n"
-                "    raw(<hex script>)                    Outputs whose scriptPubKey equals the specified hex scripts\n"
-                "\nIn the above, <pubkey> either refers to a fixed public key in hexadecimal notation, or to an xpub/xprv optionally followed by one\n"
-                "or more path elements separated by \"/\", where \"h\" represents a hardened child key.\n"
-                "For more information on output descriptors, see the documentation in the doc/descriptors.md file.\n"
-            }, {
-                {"descriptor", RPCArg::Type::STR, /* opt */ false, /* default_val */ "", "The descriptor."},
-                {"begin", RPCArg::Type::NUM, /* opt */ true, /* default_val */ "", "If a ranged descriptor is used, this specifies the beginning of the range to import."},
-                {"end", RPCArg::Type::NUM, /* opt */ true, /* default_val */ "", "If a ranged descriptor is used, this specifies the end of the range to import."}
-            }}.ToString() +
-            "\nResult:\n"
-            "[ address ] (array) the derived addresses\n"
-            "\nExamples:\n"
-            "\nFirst three native segwit receive addresses\n"
-            + HelpExampleCli("deriveaddresses", "\"wpkh([d34db33f/84h/0h/0h]xpub6DJ2dNUysrn5Vt36jH2KLBT2i1auw1tTSSomg8PhqNiUtx8QX2SvC9nrHu81fT41fvDUnhMjEzQgXnQjKEu3oaqMSzhSrHMxyyoEAmUHQbY/0/*)\" 0 2") +
-            ""
-        );
+            RPCHelpMan{"deriveaddresses",
+                {"\nDerives one or more addresses corresponding to an output descriptor.\n"
+                 "Examples of output descriptors are:\n"
+                 "    pkh(<pubkey>)                        P2PKH outputs for the given pubkey\n"
+                 "    wpkh(<pubkey>)                       Native segwit P2PKH outputs for the given pubkey\n"
+                 "    sh(multi(<n>,<pubkey>,<pubkey>,...)) P2SH-multisig outputs for the given threshold and pubkeys\n"
+                 "    raw(<hex script>)                    Outputs whose scriptPubKey equals the specified hex scripts\n"
+                 "\nIn the above, <pubkey> either refers to a fixed public key in hexadecimal notation, or to an xpub/xprv optionally followed by one\n"
+                 "or more path elements separated by \"/\", where \"h\" represents a hardened child key.\n"
+                 "For more information on output descriptors, see the documentation in the doc/descriptors.md file.\n"},
+                {
+                    {"descriptor", RPCArg::Type::STR, /* opt */ false, /* default_val */ "", "The descriptor."},
+                    {"begin", RPCArg::Type::NUM, /* opt */ true, /* default_val */ "", "If a ranged descriptor is used, this specifies the beginning of the range to import."},
+                    {"end", RPCArg::Type::NUM, /* opt */ true, /* default_val */ "", "If a ranged descriptor is used, this specifies the end of the range to import."},
+                },
+                RPCResult{
+                    "[ address ] (array) the derived addresses\n"},
+                RPCExamples{
+                    "\nFirst three native segwit receive addresses\n" + HelpExampleCli("deriveaddresses", "\"wpkh([d34db33f/84h/0h/0h]xpub6DJ2dNUysrn5Vt36jH2KLBT2i1auw1tTSSomg8PhqNiUtx8QX2SvC9nrHu81fT41fvDUnhMjEzQgXnQjKEu3oaqMSzhSrHMxyyoEAmUHQbY/0/*)\" 0 2")}}
+                .ToString());
+    }
 
     RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VNUM, UniValue::VNUM});
     const std::string desc_str = request.params[0].get_str();

Thanks, done.

grammar nit: "Range should be greater than or equal to 0"

meta-nit: #14491 uses "start", not "begin". Would be nice to sync these.

I'd add a wallet roundtrip test like:

wpkh_info = self.nodes[0].getaddressinfo(self.nodes[0].getnewaddress("", "bech32"))
# Trim the witness part of descriptor off, check pkh entry in wallet, match descriptor
pkh_desc = wpkh_info["desc"][1:]
pkh_addr = self.nodes[0].deriveaddresses(pkh_desc)
pkh_info = self.nodes[0].getaddressinfo(pkh_addr)
assert_equal(wpkh_info["hdkeypath"], pkh_info["hdkeypath"])
assert_equal(wpkh_info["pubkey"], pkh_info["pubkey"])