Add unmodified-but-with-checksum to getdescriptorinfo

Author: sipa

src/rpc/misc.cpp

@@ -136,6 +136,7 @@ UniValue getdescriptorinfo(const JSONRPCRequest& request)
             RPCResult{
             "{\n"
             "  \"descriptor\" : \"desc\",         (string) The descriptor in canonical form, without private keys\n"
+            "  \"checksum\" : \"chksum\",         (string) The checksum for the input descriptor\n"
             "  \"isrange\" : true|false,        (boolean) Whether the descriptor is ranged\n"
             "  \"issolvable\" : true|false,     (boolean) Whether the descriptor is solvable\n"
             "  \"hasprivatekeys\" : true|false, (boolean) Whether the input descriptor contained at least one private key\n"
@@ -156,6 +157,7 @@ UniValue getdescriptorinfo(const JSONRPCRequest& request)
 
     UniValue result(UniValue::VOBJ);
     result.pushKV("descriptor", desc->ToString());
+    result.pushKV("checksum", GetDescriptorChecksum(request.params[0].get_str()));
     result.pushKV("isrange", desc->IsRange());
     result.pushKV("issolvable", desc->IsSolvable());
     result.pushKV("hasprivatekeys", provider.keys.size() > 0);

src/script/descriptor.cpp

@@ -938,6 +938,14 @@ std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProv
     return nullptr;
 }
 
+std::string GetDescriptorChecksum(const std::string& descriptor)
+{
+    std::string ret;
+    Span<const char> sp(descriptor.data(), descriptor.size());
+    if (!CheckChecksum(sp, false, &ret)) return "";
+    return ret;
+}
+
 std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider)
 {
     return InferScript(script, ParseScriptContext::TOP, provider);

src/script/descriptor.h

@@ -81,6 +81,14 @@ struct Descriptor {
  */
 std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out, bool require_checksum = false);
 
+/** Get the checksum for a descriptor.
+ *
+ * If it already has one, and it is correct, return the checksum in the input.
+ * If it already has one that is wrong, return "".
+ * If it does not already have one, return the checksum that would need to be added.
+ */
+std::string GetDescriptorChecksum(const std::string& descriptor);
+
 /** Find a descriptor for the specified script, using information from provider where possible.
  *
  * A non-ranged descriptor which only generates the specified script will be returned in all

test/functional/wallet_address_types.py

@@ -175,6 +175,10 @@ def test_desc(self, node, address, multisig, typ, utxo):
         assert info['desc'] == descsum_create(info['desc'][:-9])
         # Verify that stripping the checksum and feeding it to getdescriptorinfo roundtrips
         assert info['desc'] == self.nodes[0].getdescriptorinfo(info['desc'][:-9])['descriptor']
+        assert_equal(info['desc'][-8:], self.nodes[0].getdescriptorinfo(info['desc'][:-9])['checksum'])
+        # Verify that keeping the checksum and feeding it to getdescriptorinfo roundtrips
+        assert info['desc'] == self.nodes[0].getdescriptorinfo(info['desc'])['descriptor']
+        assert_equal(info['desc'][-8:], self.nodes[0].getdescriptorinfo(info['desc'])['checksum'])
 
         if not multisig and typ == 'legacy':
             # P2PKH