Add support for watch-only addresses

Changes:
* Add Add/Have WatchOnly methods to CKeyStore, and implementations
  in CBasicKeyStore.
* Add similar methods to CWallet, and support entries for it in
  CWalletDB.
* Make IsMine in script/wallet return a new enum 'isminetype',
  rather than a boolean. This allows distinguishing between
  spendable and unspendable coins.
* Add a field fSpendable to COutput (GetAvailableCoins' return type).
* Mark watchonly coins in listunspent as 'watchonly': true.
* Add 'watchonly' to validateaddress, suppressing script/pubkey/...
  in this case.

Based on a patch by Eric Lombrozo.

Conflicts:
	src/qt/walletmodel.cpp
	src/rpcserver.cpp
	src/wallet.cpp

1 files changed, 45 insertions, 0 deletions

diff --git a/src/rpcdump.cpp b/src/rpcdump.cpp
index 593e0d2b6b..5b325c46ee 100644
--- a/src/rpcdump.cpp
+++ b/src/rpcdump.cpp
@@ -133,6 +133,51 @@ Value importprivkey(const Array& params, bool fHelp)
     return Value::null;
 }
 
+Value importaddress(const Array& params, bool fHelp)
+{
+    if (fHelp || params.size() < 1 || params.size() > 3)
+        throw runtime_error(
+            "importaddress <address> [label] [rescan=true]\n"
+            "Adds an address that can be watched as if it were in your wallet but cannot be used to spend.");
+
+    CBitcoinAddress address(params[0].get_str());
+    if (!address.IsValid())
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid Bitcoin address");
+    CTxDestination dest;
+    dest = address.Get();
+
+    string strLabel = "";
+    if (params.size() > 1)
+        strLabel = params[1].get_str();
+
+    // Whether to perform rescan after import
+    bool fRescan = true;
+    if (params.size() > 2)
+        fRescan = params[2].get_bool();
+
+    {
+        LOCK2(cs_main, pwalletMain->cs_wallet);
+
+        // Don't throw error in case an address is already there
+        if (pwalletMain->HaveWatchOnly(dest))
+            return Value::null;
+
+        pwalletMain->MarkDirty();
+        pwalletMain->SetAddressBook(dest, strLabel, "receive");
+
+        if (!pwalletMain->AddWatchOnly(dest))
+            throw JSONRPCError(RPC_WALLET_ERROR, "Error adding address to wallet");
+
+        if (fRescan)
+        {
+            pwalletMain->ScanForWalletTransactions(chainActive.Genesis(), true);
+            pwalletMain->ReacceptWalletTransactions();
+        }
+    }
+
+    return Value::null;
+}
+
 Value importwallet(const Array& params, bool fHelp)
 {
     if (fHelp || params.size() != 1)