Mark PSBTs spending unspendable outputs as invalid in analysis

src/node/psbt.cpp

@@ -7,6 +7,7 @@
 #include <node/psbt.h>
 #include <policy/policy.h>
 #include <policy/settings.h>
+#include <tinyformat.h>
 
 #include <numeric>
 
@@ -39,6 +40,11 @@ PSBTAnalysis AnalyzePSBT(PartiallySignedTransaction psbtx)
             calc_fee = false;
         }
 
+        if (!utxo.IsNull() && utxo.scriptPubKey.IsUnspendable()) {
+            result.SetInvalid(strprintf("PSBT is not valid. Input %u spends unspendable output", i));
+            return result;
+        }
+
         // Check if it is final
         if (!utxo.IsNull() && !PSBTInputSigned(input)) {
             input_analysis.is_final = false;

test/functional/rpc_psbt.py

@@ -416,5 +416,10 @@ class PSBTTest(BitcoinTestFramework):
         analyzed = self.nodes[0].analyzepsbt(signed)
         assert analyzed['inputs'][0]['has_utxo'] and analyzed['inputs'][0]['is_final'] and analyzed['next'] == 'extractor'
 
+        self.log.info("PSBT spending unspendable outputs should have error message and Creator as next")
+        analysis = self.nodes[0].analyzepsbt('cHNidP8BAJoCAAAAAljoeiG1ba8MI76OcHBFbDNvfLqlyHV5JPVFiHuyq911AAAAAAD/////g40EJ9DsZQpoqka7CwmK6kQiwHGyyng1Kgd5WdB86h0BAAAAAP////8CcKrwCAAAAAAWAEHYXCtx0AYLCcmIauuBXlCZHdoSTQDh9QUAAAAAFv8/wADXYP/7//////8JxOh0LR2HAI8AAAAAAAEBIADC6wsAAAAAF2oUt/X69ELjeX2nTof+fZ10l+OyAokDAQcJAwEHEAABAACAAAEBIADC6wsAAAAAF2oUt/X69ELjeX2nTof+fZ10l+OyAokDAQcJAwEHENkMak8AAAAA')
+        assert_equal(analysis['next'], 'creator')
+        assert_equal(analysis['error'], 'PSBT is not valid. Input 0 spends unspendable output')
+
 if __name__ == '__main__':
     PSBTTest().main()