rpc: simplify getaddressinfo labels, deprecate previous behavior

- change the value returned in the RPC getaddressinfo `labels` field to an array
  of label name strings

- deprecate the previous behavior of returning a JSON hash structure containing
  label `name` and address `purpose` key/value pairs

- update the relevant tests

1 files changed, 21 insertions, 13 deletions

diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index a9475a0ce4..5deb7817bd 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -3744,18 +3744,20 @@ UniValue getaddressinfo(const JSONRPCRequest& request)
             "                                                         getaddressinfo output fields for the embedded address, excluding metadata (timestamp, hdkeypath,\n"
             "                                                         hdseedid) and relation to the wallet (ismine, iswatchonly).\n"
             "  \"iscompressed\" : true|false,        (boolean, optional) If the pubkey is compressed.\n"
-            "  \"label\" :  \"label\"                  (string) The label associated with the address. Defaults to \"\". Equivalent to the name field in the labels array.\n"
+            "  \"label\" :  \"label\"                  (string) The label associated with the address. Defaults to \"\". Equivalent to the label name in the labels array below.\n"
             "  \"timestamp\" : timestamp,            (number, optional) The creation time of the key, if available, expressed in " + UNIX_EPOCH_TIME + ".\n"
             "  \"hdkeypath\" : \"keypath\"             (string, optional) The HD keypath, if the key is HD and available.\n"
             "  \"hdseedid\" : \"<hash160>\"            (string, optional) The Hash160 of the HD seed.\n"
             "  \"hdmasterfingerprint\" : \"<hash160>\" (string, optional) The fingerprint of the master key.\n"
-            "  \"labels\"                            (object) An array of labels associated with the address. Currently limited to one label but returned\n"
+            "  \"labels\"                            (json object) An array of labels associated with the address. Currently limited to one label but returned\n"
             "                                               as an array to keep the API stable if multiple labels are enabled in the future.\n"
             "    [\n"
+            "      \"label name\" (string) The label name. Defaults to \"\". Equivalent to the label field above.\n\n"
+            "      DEPRECATED, will be removed in 0.21. To re-enable, launch bitcoind with `-deprecatedrpc=labelspurpose`:\n"
             "      { (json object of label data)\n"
-            "        \"name\": \"label name\" (string) The label name. Defaults to \"\". Equivalent to the label field above.\n"
-            "        \"purpose\": \"purpose\" (string) The purpose of the associated address (send or receive).\n"
-            "      },...\n"
+            "        \"name\" : \"label name\" (string) The label name. Defaults to \"\". Equivalent to the label field above.\n"
+            "        \"purpose\" : \"purpose\" (string) The purpose of the associated address (send or receive).\n"
+            "      }\n"
             "    ]\n"
             "}\n"
                 },
@@ -3769,7 +3771,6 @@ UniValue getaddressinfo(const JSONRPCRequest& request)
 
     UniValue ret(UniValue::VOBJ);
     CTxDestination dest = DecodeDestination(request.params[0].get_str());
-
     // Make sure the destination is valid
     if (!IsValidDestination(dest)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
@@ -3800,7 +3801,7 @@ UniValue getaddressinfo(const JSONRPCRequest& request)
 
     // Return label field if existing. Currently only one label can be
     // associated with an address, so the label should be equivalent to the
-    // value of the name key/value pair in the labels hash array below.
+    // value of the name key/value pair in the labels array below.
     if (pwallet->mapAddressBook.count(dest)) {
         ret.pushKV("label", pwallet->mapAddressBook[dest].name);
     }
@@ -3819,15 +3820,22 @@ UniValue getaddressinfo(const JSONRPCRequest& request)
         }
     }
 
-    // Return a labels array containing a hash of key/value pairs for the label
-    // name and address purpose. The name value is equivalent to the label field
-    // above. Currently only one label can be associated with an address, but we
-    // return an array so the API remains stable if we allow multiple labels to
-    // be associated with an address in the future.
+    // Return a `labels` array containing the label associated with the address,
+    // equivalent to the `label` field above. Currently only one label can be
+    // associated with an address, but we return an array so the API remains
+    // stable if we allow multiple labels to be associated with an address in
+    // the future.
+    //
+    // DEPRECATED: The previous behavior of returning an array containing a JSON
+    // object of `name` and `purpose` key/value pairs has been deprecated.
     UniValue labels(UniValue::VARR);
     std::map<CTxDestination, CAddressBookData>::iterator mi = pwallet->mapAddressBook.find(dest);
     if (mi != pwallet->mapAddressBook.end()) {
-        labels.push_back(AddressBookDataToJSON(mi->second, true));
+        if (pwallet->chain().rpcEnableDeprecated("labelspurpose")) {
+            labels.push_back(AddressBookDataToJSON(mi->second, true));
+        } else {
+            labels.push_back(mi->second.name);
+        }
     }
     ret.pushKV("labels", std::move(labels));