SegWit wallet support

This introduces two command line flags (-addresstype and -changetype) which control
the type of addresses/outputs created by the GUI and RPCs. Certain RPCs allow
overriding these (`getnewaddress` and `getrawchangeaddress`). Supported types
are "legacy" (P2PKH and P2SH-multisig), "p2sh-segwit" (P2SH-P2WPKH and P2SH-P2WSH-multisig),
and "bech32" (P2WPKH and P2WSH-multisig).

A few utility functions are added to the wallet to construct different address type
and to add the necessary entries to the wallet file to be compatible with earlier
versions (see `CWallet::LearnRelatedScripts`, `GetDestinationForKey`,
`GetAllDestinationsForKey`, `CWallet::AddAndGetDestinationForScript`).

1 files changed, 16 insertions, 19 deletions

diff --git a/src/qt/paymentserver.cpp b/src/qt/paymentserver.cpp
index 510a3783ae..48462f9b5f 100644
--- a/src/qt/paymentserver.cpp
+++ b/src/qt/paymentserver.cpp
@@ -636,27 +636,24 @@ void PaymentServer::fetchPaymentACK(CWallet* wallet, const SendCoinsRecipient& r
     // Create a new refund address, or re-use:
     QString account = tr("Refund from %1").arg(recipient.authenticatedMerchant);
     std::string strAccount = account.toStdString();
-    std::set<CTxDestination> refundAddresses = wallet->GetAccountAddresses(strAccount);
-    if (!refundAddresses.empty()) {
-        CScript s = GetScriptForDestination(*refundAddresses.begin());
+    CPubKey newKey;
+    if (wallet->GetKeyFromPool(newKey)) {
+        // BIP70 requests encode the scriptPubKey directly, so we are not restricted to address
+        // types supported by the receiver. As a result, we choose the address format we also
+        // use for change. Despite an actual payment and not change, this is a close match:
+        // it's the output type we use subject to privacy issues, but not restricted by what
+        // other software supports.
+        wallet->LearnRelatedScripts(newKey, g_change_type);
+        CTxDestination dest = GetDestinationForKey(newKey, g_change_type);
+        wallet->SetAddressBook(dest, strAccount, "refund");
+
+        CScript s = GetScriptForDestination(dest);
         payments::Output* refund_to = payment.add_refund_to();
         refund_to->set_script(&s[0], s.size());
-    }
-    else {
-        CPubKey newKey;
-        if (wallet->GetKeyFromPool(newKey)) {
-            CKeyID keyID = newKey.GetID();
-            wallet->SetAddressBook(keyID, strAccount, "refund");
-
-            CScript s = GetScriptForDestination(keyID);
-            payments::Output* refund_to = payment.add_refund_to();
-            refund_to->set_script(&s[0], s.size());
-        }
-        else {
-            // This should never happen, because sending coins should have
-            // just unlocked the wallet and refilled the keypool.
-            qWarning() << "PaymentServer::fetchPaymentACK: Error getting refund key, refund_to not set";
-        }
+    } else {
+        // This should never happen, because sending coins should have
+        // just unlocked the wallet and refilled the keypool.
+        qWarning() << "PaymentServer::fetchPaymentACK: Error getting refund key, refund_to not set";
     }
 
     int length = payment.ByteSize();