Make SignatureData able to store signatures and scripts

In addition to having the scriptSig and scriptWitness, have SignatureData
also be able to store just the signatures (pubkeys mapped to sigs) and
scripts (script ids mapped to scripts).

Also have DataFromTransaction be able to extract signatures and scripts
from the scriptSig and scriptWitness of an input to put them in SignatureData.

Adds a new SignatureChecker which takes a SignatureData and puts pubkeys
and signatures into it when it successfully verifies a signature.

Adds a new field in SignatureData which stores whether the SignatureData
was complete. This allows us to also update the scriptSig and
scriptWitness to the final one when updating a SignatureData with another
one.

1 files changed, 13 insertions, 4 deletions

diff --git a/src/script/sign.h b/src/script/sign.h
index 8ef0306bfe..7dc4bedb06 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -53,9 +53,18 @@ public:
 /** A signature creator that just produces 72-byte empty signatures. */
 extern const BaseSignatureCreator& DUMMY_SIGNATURE_CREATOR;
 
+typedef std::pair<CPubKey, std::vector<unsigned char>> SigPair;
+
+// This struct contains information from a transaction input and also contains signatures for that input.
+// The information contained here can be used to create a signature and is also filled by ProduceSignature
+// in order to construct final scriptSigs and scriptWitnesses.
 struct SignatureData {
-    CScript scriptSig;
-    CScriptWitness scriptWitness;
+    bool complete = false; ///< Stores whether the scriptSig and scriptWitness are complete
+    CScript scriptSig; ///< The scriptSig of an input. Contains complete signatures or the traditional partial signatures format
+    CScript redeem_script; ///< The redeemScript (if any) for the input
+    CScript witness_script; ///< The witnessScript (if any) for the input. witnessScripts are used in P2WSH outputs.
+    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.
 
     SignatureData() {}
     explicit SignatureData(const CScript& script) : scriptSig(script) {}
@@ -71,8 +80,8 @@ bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom,
 /** Combine two script signatures using a generic signature checker, intelligently, possibly with OP_0 placeholders. */
 SignatureData CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker, const SignatureData& scriptSig1, const SignatureData& scriptSig2);
 
-/** Extract signature data from a transaction, and insert it. */
-SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn);
+/** Extract signature data from a transaction input, and insert it. */
+SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout);
 void UpdateInput(CTxIn& input, const SignatureData& data);
 
 /* Check whether we know how to sign for an output like this, assuming we