Implement PSBT Structures and un/serialization methods per BIP 174

Author: achow101

src/pubkey.h

@@ -107,6 +107,7 @@ class CPubKey
 
     //! Simple read-only vector-like interface to the pubkey data.
     unsigned int size() const { return GetLen(vch[0]); }
+    const unsigned char* data() const { return vch; }
     const unsigned char* begin() const { return vch; }
     const unsigned char* end() const { return vch + size(); }
     const unsigned char& operator[](unsigned int pos) const { return vch[pos]; }

src/script/sign.cpp

@@ -429,3 +429,19 @@ bool IsSolvable(const SigningProvider& provider, const CScript& script)
     }
     return false;
 }
+
+
+bool PartiallySignedTransaction::IsNull() const
+{
+    return !tx && inputs.empty() && outputs.empty() && unknown.empty();
+}
+
+bool PSBTInput::IsNull() const
+{
+    return !non_witness_utxo && witness_utxo.IsNull() && partial_sigs.empty() && unknown.empty() && hd_keypaths.empty() && redeem_script.empty() && witness_script.empty();
+}
+
+bool PSBTOutput::IsNull() const
+{
+    return redeem_script.empty() && witness_script.empty() && hd_keypaths.empty() && unknown.empty();
+}