Move CTxDestination to its own file

CTxDestination is really our internal representation of an address and
doesn't really have anything to do with standard script types, so move
them to their own file.

src/addresstype.cpp

@@ -0,0 +1,150 @@
+// Copyright (c) 2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://www.opensource.org/licenses/mit-license.php.
+
+#include <addresstype.h>
+#include <script/script.h>
+#include <script/standard.h>
+#include <hash.h>
+#include <pubkey.h>
+#include <uint256.h>
+#include <util/hash_type.h>
+
+#include <vector>
+
+typedef std::vector<unsigned char> valtype;
+
+ScriptHash::ScriptHash(const CScript& in) : BaseHash(Hash160(in)) {}
+ScriptHash::ScriptHash(const CScriptID& in) : BaseHash(static_cast<uint160>(in)) {}
+
+PKHash::PKHash(const CPubKey& pubkey) : BaseHash(pubkey.GetID()) {}
+PKHash::PKHash(const CKeyID& pubkey_id) : BaseHash(pubkey_id) {}
+
+WitnessV0KeyHash::WitnessV0KeyHash(const CPubKey& pubkey) : BaseHash(pubkey.GetID()) {}
+WitnessV0KeyHash::WitnessV0KeyHash(const PKHash& pubkey_hash) : BaseHash(static_cast<uint160>(pubkey_hash)) {}
+
+CKeyID ToKeyID(const PKHash& key_hash)
+{
+    return CKeyID{static_cast<uint160>(key_hash)};
+}
+
+CKeyID ToKeyID(const WitnessV0KeyHash& key_hash)
+{
+    return CKeyID{static_cast<uint160>(key_hash)};
+}
+
+CScriptID ToScriptID(const ScriptHash& script_hash)
+{
+    return CScriptID{static_cast<uint160>(script_hash)};
+}
+
+WitnessV0ScriptHash::WitnessV0ScriptHash(const CScript& in)
+{
+    CSHA256().Write(in.data(), in.size()).Finalize(begin());
+}
+
+bool ExtractDestination(const CScript& scriptPubKey, CTxDestination& addressRet)
+{
+    std::vector<valtype> vSolutions;
+    TxoutType whichType = Solver(scriptPubKey, vSolutions);
+
+    switch (whichType) {
+    case TxoutType::PUBKEY: {
+        CPubKey pubKey(vSolutions[0]);
+        if (!pubKey.IsValid())
+            return false;
+
+        addressRet = PKHash(pubKey);
+        return true;
+    }
+    case TxoutType::PUBKEYHASH: {
+        addressRet = PKHash(uint160(vSolutions[0]));
+        return true;
+    }
+    case TxoutType::SCRIPTHASH: {
+        addressRet = ScriptHash(uint160(vSolutions[0]));
+        return true;
+    }
+    case TxoutType::WITNESS_V0_KEYHASH: {
+        WitnessV0KeyHash hash;
+        std::copy(vSolutions[0].begin(), vSolutions[0].end(), hash.begin());
+        addressRet = hash;
+        return true;
+    }
+    case TxoutType::WITNESS_V0_SCRIPTHASH: {
+        WitnessV0ScriptHash hash;
+        std::copy(vSolutions[0].begin(), vSolutions[0].end(), hash.begin());
+        addressRet = hash;
+        return true;
+    }
+    case TxoutType::WITNESS_V1_TAPROOT: {
+        WitnessV1Taproot tap;
+        std::copy(vSolutions[0].begin(), vSolutions[0].end(), tap.begin());
+        addressRet = tap;
+        return true;
+    }
+    case TxoutType::WITNESS_UNKNOWN: {
+        WitnessUnknown unk;
+        unk.version = vSolutions[0][0];
+        std::copy(vSolutions[1].begin(), vSolutions[1].end(), unk.program);
+        unk.length = vSolutions[1].size();
+        addressRet = unk;
+        return true;
+    }
+    case TxoutType::MULTISIG:
+    case TxoutType::NULL_DATA:
+    case TxoutType::NONSTANDARD:
+        return false;
+    } // no default case, so the compiler can warn about missing cases
+    assert(false);
+}
+
+namespace {
+class CScriptVisitor
+{
+public:
+    CScript operator()(const CNoDestination& dest) const
+    {
+        return CScript();
+    }
+
+    CScript operator()(const PKHash& keyID) const
+    {
+        return CScript() << OP_DUP << OP_HASH160 << ToByteVector(keyID) << OP_EQUALVERIFY << OP_CHECKSIG;
+    }
+
+    CScript operator()(const ScriptHash& scriptID) const
+    {
+        return CScript() << OP_HASH160 << ToByteVector(scriptID) << OP_EQUAL;
+    }
+
+    CScript operator()(const WitnessV0KeyHash& id) const
+    {
+        return CScript() << OP_0 << ToByteVector(id);
+    }
+
+    CScript operator()(const WitnessV0ScriptHash& id) const
+    {
+        return CScript() << OP_0 << ToByteVector(id);
+    }
+
+    CScript operator()(const WitnessV1Taproot& tap) const
+    {
+        return CScript() << OP_1 << ToByteVector(tap);
+    }
+
+    CScript operator()(const WitnessUnknown& id) const
+    {
+        return CScript() << CScript::EncodeOP_N(id.version) << std::vector<unsigned char>(id.program, id.program + id.length);
+    }
+};
+} // namespace
+
+CScript GetScriptForDestination(const CTxDestination& dest)
+{
+    return std::visit(CScriptVisitor(), dest);
+}
+
+bool IsValidDestination(const CTxDestination& dest) {
+    return dest.index() != 0;
+}