Merge #13932: Additional utility RPCs for PSBT

540729ef4bf1b6c6da1ec795e441d2ce56a9a58b Implement analyzepsbt RPC and tests (Andrew Chow)
77542cf2a5f8abb97dd46f782c1b0199cc062033 Move PSBT UTXO fetching to a separate method (Andrew Chow)
cb40b3abd4514361a024a1e7a1a281da9261261b Figure out what is missing during signing (Andrew Chow)
08f749c9147a5f3fdbbd880e0974b97084429002 Implement joinpsbts RPC and tests (Andrew Chow)
7344a7b9984b99882e136efc8ad48fb31740df93 Implement utxoupdatepsbt RPC and tests (Andrew Chow)

Pull request description:

  This PR adds 3 new utility RPCs for interacting with PSBTs.

  `utxoupdatepsbt` updates a PSBT with UTXO information from the node. It only works with witness UTXOs because full transactions (as would be needed for non-witness UTXOs) are not available unless txindex is enabled.

  `joinpsbts` joins the inputs from multiple distinct PSBTs into one PSBT. e.g. if PSBT 1 has inputs 1 and 2, and PSBT 2 has inputs 3 and 4, `joinpsbts` would create a new PSBT with inputs 1, 2, 3, and 4.

  `analyzepsbt` analyzes a PSBT and determines the current state of it and all of its inputs, and the next step that needs to be done.

Tree-SHA512: 3c1fa302201abca76a8901d0c2be7b4ccbce334d989533c215f8b3e50e22f2f018ce6209544b26789f58f5980a253c0655111e1e20d47d5656e0414c64891a5c

2 files changed, 17 insertions, 2 deletions

diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 9d6a390ea2..320956d0c4 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -83,6 +83,8 @@ static bool CreateSig(const BaseSignatureCreator& creator, SignatureData& sigdat
         assert(i.second);
         return true;
     }
+    // Could not make signature or signature not found, add keyid to missing
+    sigdata.missing_sigs.push_back(keyid);
     return false;
 }
 
@@ -116,17 +118,24 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
     case TX_PUBKEYHASH: {
         CKeyID keyID = CKeyID(uint160(vSolutions[0]));
         CPubKey pubkey;
-        if (!GetPubKey(provider, sigdata, keyID, pubkey)) return false;
+        if (!GetPubKey(provider, sigdata, keyID, pubkey)) {
+            // Pubkey could not be found, add to missing
+            sigdata.missing_pubkeys.push_back(keyID);
+            return false;
+        }
         if (!CreateSig(creator, sigdata, provider, sig, pubkey, scriptPubKey, sigversion)) return false;
         ret.push_back(std::move(sig));
         ret.push_back(ToByteVector(pubkey));
         return true;
     }
     case TX_SCRIPTHASH:
-        if (GetCScript(provider, sigdata, uint160(vSolutions[0]), scriptRet)) {
+        h160 = uint160(vSolutions[0]);
+        if (GetCScript(provider, sigdata, h160, scriptRet)) {
             ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
             return true;
         }
+        // Could not find redeemScript, add to missing
+        sigdata.missing_redeem_script = h160;
         return false;
 
     case TX_MULTISIG: {
@@ -154,6 +163,8 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
             ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
             return true;
         }
+        // Could not find witnessScript, add to missing
+        sigdata.missing_witness_script = uint256(vSolutions[0]);
         return false;
 
     default:
diff --git a/src/script/sign.h b/src/script/sign.h
index 3e9a3b38c6..491fb54c45 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -131,6 +131,10 @@ struct SignatureData {
     CScriptWitness scriptWitness; ///< The scriptWitness of an input. Contains complete signatures or the traditional partial signatures format. scriptWitness is part of a transaction input per BIP 144.
     std::map<CKeyID, SigPair> signatures; ///< BIP 174 style partial signatures for the input. May contain all signatures necessary for producing a final scriptSig or scriptWitness.
     std::map<CKeyID, std::pair<CPubKey, KeyOriginInfo>> misc_pubkeys;
+    std::vector<CKeyID> missing_pubkeys; ///< KeyIDs of pubkeys which could not be found
+    std::vector<CKeyID> missing_sigs; ///< KeyIDs of pubkeys for signatures which could not be found
+    uint160 missing_redeem_script; ///< ScriptID of the missing redeemScript (if any)
+    uint256 missing_witness_script; ///< SHA256 of the missing witnessScript (if any)
 
     SignatureData() {}
     explicit SignatureData(const CScript& script) : scriptSig(script) {}