Update EncodeDestination(), DecodeDestination() and IsValidDestination()

An overview of commits that implement an initial switch from using
CBitcoinAddress to CTxDestination using bech32 (in line with Bitcoin's
implementation). A 80% implementation (not cleaned up) can be found in our archives:
- cevap/ion-old-v3@3b30fd0
- cevap/ion-old-v3@f8ee3a8
- cevap/ion-old-v3@7f87033
- cevap/ion-old-v3@f0d2206
- cevap/ion-old-v3@dbddc7b
- cevap/ion-old-v3@e834f27
- cevap/ion-old-v3@2c467e1
- cevap/ion-old-v3@ef36201
- cevap/ion-old-v3@3d6e391

Implementing this switch in full is future work, which needs:
- bitcoin#11117
- bitcoin#11167
- bitcoin#11372

src/Makefile.am

@@ -116,6 +116,7 @@ BITCOIN_CORE_H = \
   activemasternode.h \
   addrman.h \
   base58.h \
+  bech32.h \
   bip38.h \
   bloom.h \
   blocksignature.h \
@@ -151,6 +152,7 @@ BITCOIN_CORE_H = \
   invalid.h \
   invalid_outpoints.json.h \
   invalid_serials.json.h \
+  ionaddrenc.h \
   kernel.h \
   swifttx.h \
   key.h \
@@ -571,10 +573,13 @@ libbitcoin_common_a_SOURCES = \
   allocators.cpp \
   amount.cpp \
   base58.cpp \
+  bech32.cpp \
   bip38.cpp \
   chainparams.cpp \
   coins.cpp \
   compressor.cpp \
+  dstencode.cpp \
+  ionaddrenc.cpp \
   primitives/block.cpp \
   xion/deterministicmint.cpp \
   primitives/transaction.cpp \

src/base58.cpp

@@ -319,3 +319,90 @@ bool CBitcoinSecret::SetString(const std::string& strSecret)
 {
     return SetString(strSecret.c_str());
 }
+
+namespace
+{
+class DestinationEncoder : public boost::static_visitor<std::string>
+{
+private:
+    const CChainParams& m_params;
+
+public:
+    DestinationEncoder(const CChainParams& params) : m_params(params) {}
+
+    std::string operator()(const CKeyID& id) const
+    {
+        std::vector<unsigned char> data = m_params.Base58Prefix(CChainParams::PUBKEY_ADDRESS);
+        data.insert(data.end(), id.begin(), id.end());
+        return EncodeBase58Check(data);
+    }
+
+    std::string operator()(const CScriptID& id) const
+    {
+        std::vector<unsigned char> data = m_params.Base58Prefix(CChainParams::SCRIPT_ADDRESS);
+        data.insert(data.end(), id.begin(), id.end());
+        return EncodeBase58Check(data);
+    }
+
+/*
+    std::string operator()(const WitnessV0KeyHash& id) const
+    {
+        std::vector<unsigned char> data = {0};
+        ConvertBits<8, 5, true>(data, id.begin(), id.end());
+        return bech32::Encode(m_params.Bech32HRP(), data);
+    }
+
+    std::string operator()(const WitnessV0ScriptHash& id) const
+    {
+        std::vector<unsigned char> data = {0};
+        ConvertBits<8, 5, true>(data, id.begin(), id.end());
+        return bech32::Encode(m_params.Bech32HRP(), data);
+    }
+
+    std::string operator()(const WitnessUnknown& id) const
+    {
+        if (id.version < 1 || id.version > 16 || id.length < 2 || id.length > 40) {
+            return {};
+        }
+        std::vector<unsigned char> data = {(unsigned char)id.version};
+        ConvertBits<8, 5, true>(data, id.program, id.program + id.length);
+        return bech32::Encode(m_params.Bech32HRP(), data);
+    }
+*/
+    std::string operator()(const CNoDestination& no) const { return {}; }
+};
+
+CTxDestination DecodeDestination(const std::string& str, const CChainParams& params)
+{
+    std::vector<unsigned char> data;
+    uint160 hash;
+    if (DecodeBase58Check(str, data)) {
+        // base58-encoded Bitcoin addresses.
+        // Public-key-hash-addresses have version 0 (or 111 testnet).
+        // The data vector contains RIPEMD160(SHA256(pubkey)), where pubkey is the serialized public key.
+        const std::vector<unsigned char>& pubkey_prefix = params.Base58Prefix(CChainParams::PUBKEY_ADDRESS);
+        if (data.size() == hash.size() + pubkey_prefix.size() && std::equal(pubkey_prefix.begin(), pubkey_prefix.end(), data.begin())) {
+            std::copy(data.begin() + pubkey_prefix.size(), data.end(), hash.begin());
+            return CKeyID(hash);
+        }
+        // Script-hash-addresses have version 5 (or 196 testnet).
+        // The data vector contains RIPEMD160(SHA256(cscript)), where cscript is the serialized redemption script.
+        const std::vector<unsigned char>& script_prefix = params.Base58Prefix(CChainParams::SCRIPT_ADDRESS);
+        if (data.size() == hash.size() + script_prefix.size() && std::equal(script_prefix.begin(), script_prefix.end(), data.begin())) {
+            std::copy(data.begin() + script_prefix.size(), data.end(), hash.begin());
+            return CScriptID(hash);
+        }
+    }
+    return CNoDestination();
+}
+} // anon namespace
+
+std::string EncodeLegacyAddr(const CTxDestination &dest, const CChainParams &params)
+{
+    return boost::apply_visitor(DestinationEncoder(params), dest);
+}
+
+CTxDestination DecodeLegacyAddr(const std::string &str, const CChainParams &params)
+{
+    return DecodeDestination(str, params);
+}

src/base58.h

@@ -180,4 +180,10 @@ std::string EncodeLegacyAddr(const CTxDestination &dest, const CChainParams &);
 /// Decode an old-style bitcoin address
 CTxDestination DecodeLegacyAddr(const std::string &str, const CChainParams &);
 
+/// Encode an old-style bitcoin address
+std::string EncodeLegacyAddr(const CTxDestination &dest, const CChainParams &);
+
+/// Decode an old-style bitcoin address
+CTxDestination DecodeLegacyAddr(const std::string &str, const CChainParams &);
+
 #endif // BITCOIN_BASE58_H

src/script/standard.cpp

@@ -308,3 +308,7 @@ CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys)
     script << CScript::EncodeOP_N(keys.size()) << OP_CHECKMULTISIG;
     return script;
 }
+
+bool IsValidDestination(const CTxDestination& dest) {
+    return dest.which() != 0;
+}

src/script/standard.h

@@ -96,6 +96,8 @@ class CNoDestination {
  *  A CTxDestination is the internal data type encoded in a CBitcoinAddress
  */
 typedef boost::variant<CNoDestination, CKeyID, CScriptID> CTxDestination;
+/** Check whether a CTxDestination is a CNoDestination. */
+bool IsValidDestination(const CTxDestination& dest);
 
 const char* GetTxnOutputType(txnouttype t);