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, 39 insertions, 13 deletions

diff --git a/src/script.cpp b/src/script.cpp
index e1b6985408..0ef0126255 100644
--- a/src/script.cpp
+++ b/src/script.cpp
@@ -1456,36 +1456,57 @@ public:
     bool operator()(const CScriptID &scriptID) const { return keystore->HaveCScript(scriptID); }
 };
 
-bool IsMine(const CKeyStore &keystore, const CTxDestination &dest)
+isminetype IsMine(const CKeyStore &keystore, const CTxDestination &dest)
 {
-    return boost::apply_visitor(CKeyStoreIsMineVisitor(&keystore), dest);
+    if (boost::apply_visitor(CKeyStoreIsMineVisitor(&keystore), dest))
+        return MINE_SPENDABLE;
+    if (keystore.HaveWatchOnly(dest))
+        return MINE_WATCH_ONLY;
+    return MINE_NO;
 }
 
-bool IsMine(const CKeyStore &keystore, const CScript& scriptPubKey)
+isminetype IsMine(const CKeyStore &keystore, const CScript& scriptPubKey)
 {
     vector<valtype> vSolutions;
     txnouttype whichType;
-    if (!Solver(scriptPubKey, whichType, vSolutions))
-        return false;
+    if (!Solver(scriptPubKey, whichType, vSolutions)) {
+        if (keystore.HaveWatchOnly(scriptPubKey.GetID()))
+            return MINE_WATCH_ONLY;
+        return MINE_NO;
+    }
 
     CKeyID keyID;
     switch (whichType)
     {
     case TX_NONSTANDARD:
     case TX_NULL_DATA:
-        return false;
+        break;
     case TX_PUBKEY:
         keyID = CPubKey(vSolutions[0]).GetID();
-        return keystore.HaveKey(keyID);
+        if (keystore.HaveKey(keyID))
+            return MINE_SPENDABLE;
+        if (keystore.HaveWatchOnly(keyID))
+            return MINE_WATCH_ONLY;
+        break;
     case TX_PUBKEYHASH:
         keyID = CKeyID(uint160(vSolutions[0]));
-        return keystore.HaveKey(keyID);
+        if (keystore.HaveKey(keyID))
+            return MINE_SPENDABLE;
+        if (keystore.HaveWatchOnly(keyID))
+            return MINE_WATCH_ONLY;
+        break;
     case TX_SCRIPTHASH:
     {
+        CScriptID scriptID = CScriptID(uint160(vSolutions[0]));
         CScript subscript;
-        if (!keystore.GetCScript(CScriptID(uint160(vSolutions[0])), subscript))
-            return false;
-        return IsMine(keystore, subscript);
+        if (keystore.GetCScript(scriptID, subscript)) {
+            isminetype ret = IsMine(keystore, subscript);
+            if (ret)
+                return ret;
+        }
+        if (keystore.HaveWatchOnly(scriptID))
+            return MINE_WATCH_ONLY;
+        break;
     }
     case TX_MULTISIG:
     {
@@ -1495,10 +1516,15 @@ bool IsMine(const CKeyStore &keystore, const CScript& scriptPubKey)
         // them) enable spend-out-from-under-you attacks, especially
         // in shared-wallet situations.
         vector<valtype> keys(vSolutions.begin()+1, vSolutions.begin()+vSolutions.size()-1);
-        return HaveKeys(keys, keystore) == keys.size();
+        if (HaveKeys(keys, keystore) == keys.size())
+            return MINE_SPENDABLE;
+        break;
     }
     }
-    return false;
+
+    if (keystore.HaveWatchOnly(scriptPubKey.GetID()))
+        return MINE_WATCH_ONLY;
+    return MINE_NO;
 }
 
 bool ExtractDestination(const CScript& scriptPubKey, CTxDestination& addressRet)