Use boost::asio::deadline_timer for walletpassphrase timeout

New method in bitcoinrpc:  RunLater, that uses a map of deadline
timers to run a function later.

Behavior of walletpassphrase is changed; before, calling
walletpassphrase again before the lock timeout passed
would result in: Error: Wallet is already unlocked.

You would have to call lockwallet before walletpassphrase.

Now: the last walletpassphrase with correct password
wins, and overrides any previous timeout.

Fixes issue# 1961 which was caused by spawning too many threads.

Test plan:

Start with encrypted wallet, password 'foo'
NOTE:
 python -c 'import time; print("%d"%time.time())'
... will tell you current unix timestamp.

Try:

walletpassphrase foo 600
getinfo
EXPECT: unlocked_until is about 10 minutes in the future

walletpassphrase foo 1
sleep 2
sendtoaddress mun74Bvba3B1PF2YkrF4NsgcJwHXXh12LF 11
EXPECT: Error: Please enter the wallet passphrase with walletpassphrase first.

walletpassphrase foo 600
walletpassphrase foo 0
getinfo
EXPECT: wallet is locked (unlocked_until is 0)

walletpassphrase foo 10
walletpassphrase foo 600
getinfo
EXPECT: wallet is unlocked until 10 minutes in future

walletpassphrase foo 60
walletpassphrase bar 600
EXPECT: Error, incorrect passphrase
getinfo
EXPECT: wallet still scheduled to lock 60 seconds from first (successful) walletpassphrase

src/bitcoinrpc.cpp

@@ -11,17 +11,17 @@
 #include "bitcoinrpc.h"
 #include "db.h"
 
+#include <boost/algorithm/string.hpp>
 #include <boost/asio.hpp>
 #include <boost/asio/ip/v6_only.hpp>
+#include <boost/asio/ssl.hpp>
 #include <boost/bind.hpp>
 #include <boost/filesystem.hpp>
+#include <boost/filesystem/fstream.hpp>
 #include <boost/foreach.hpp>
 #include <boost/iostreams/concepts.hpp>
 #include <boost/iostreams/stream.hpp>
-#include <boost/algorithm/string.hpp>
 #include <boost/lexical_cast.hpp>
-#include <boost/asio/ssl.hpp>
-#include <boost/filesystem/fstream.hpp>
 #include <boost/shared_ptr.hpp>
 #include <list>
 
@@ -34,6 +34,7 @@ static std::string strRPCUserColonPass;
 
 // These are created by StartRPCThreads, destroyed in StopRPCThreads
 static asio::io_service* rpc_io_service = NULL;
+static map<string, boost::shared_ptr<deadline_timer> > deadlineTimers;
 static ssl::context* rpc_ssl_context = NULL;
 static boost::thread_group* rpc_worker_group = NULL;
 
@@ -843,6 +844,7 @@ void StopRPCThreads()
 {
     if (rpc_io_service == NULL) return;
 
+    deadlineTimers.clear();
     rpc_io_service->stop();
     rpc_worker_group->join_all();
     delete rpc_worker_group; rpc_worker_group = NULL;
@@ -850,6 +852,26 @@ void StopRPCThreads()
     delete rpc_io_service; rpc_io_service = NULL;
 }
 
+void RPCRunHandler(const boost::system::error_code& err, boost::function<void(void)> func)
+{
+    if (!err)
+        func();
+}
+
+void RPCRunLater(const std::string& name, boost::function<void(void)> func, int64 nSeconds)
+{
+    assert(rpc_io_service != NULL);
+
+    if (deadlineTimers.count(name) == 0)
+    {
+        deadlineTimers.insert(make_pair(name,
+                                        boost::shared_ptr<deadline_timer>(new deadline_timer(*rpc_io_service))));
+    }
+    deadlineTimers[name]->expires_from_now(posix_time::seconds(nSeconds));
+    deadlineTimers[name]->async_wait(boost::bind(RPCRunHandler, _1, func));
+}
+
+
 class JSONRequest
 {
 public:

src/bitcoinrpc.h

@@ -88,6 +88,12 @@ void RPCTypeCheck(const json_spirit::Array& params,
 void RPCTypeCheck(const json_spirit::Object& o,
                   const std::map<std::string, json_spirit::Value_type>& typesExpected, bool fAllowNull=false);
 
+/*
+  Run func nSeconds from now. Uses boost deadline timers.
+  Overrides previous timer <name> (if any).
+ */
+void RPCRunLater(const std::string& name, boost::function<void(void)> func, int64 nSeconds);
+
 typedef json_spirit::Value(*rpcfn_type)(const json_spirit::Array& params, bool fHelp);
 
 class CRPCCommand

src/rpcwallet.cpp

@@ -84,7 +84,7 @@ Value getinfo(const Array& params, bool fHelp)
     obj.push_back(Pair("keypoolsize",   pwalletMain->GetKeyPoolSize()));
     obj.push_back(Pair("paytxfee",      ValueFromAmount(nTransactionFee)));
     if (pwalletMain->IsCrypted())
-        obj.push_back(Pair("unlocked_until", (boost::int64_t)nWalletUnlockTime / 1000));
+        obj.push_back(Pair("unlocked_until", (boost::int64_t)nWalletUnlockTime));
     obj.push_back(Pair("errors",        GetWarnings("statusbar")));
     return obj;
 }
@@ -1256,56 +1256,11 @@ Value keypoolrefill(const Array& params, bool fHelp)
 }
 
 
-void ThreadTopUpKeyPool(void* parg)
+static void LockWallet(CWallet* pWallet)
 {
-    // Make this thread recognisable as the key-topping-up thread
-    RenameThread("bitcoin-key-top");
-
-    pwalletMain->TopUpKeyPool();
-}
-
-void ThreadCleanWalletPassphrase(void* parg)
-{
-    // Make this thread recognisable as the wallet relocking thread
-    RenameThread("bitcoin-lock-wa");
-
-    int64 nMyWakeTime = GetTimeMillis() + *((int64*)parg) * 1000;
-
-    ENTER_CRITICAL_SECTION(cs_nWalletUnlockTime);
-
-    if (nWalletUnlockTime == 0)
-    {
-        nWalletUnlockTime = nMyWakeTime;
-
-        do
-        {
-            if (nWalletUnlockTime==0)
-                break;
-            int64 nToSleep = nWalletUnlockTime - GetTimeMillis();
-            if (nToSleep <= 0)
-                break;
-
-            LEAVE_CRITICAL_SECTION(cs_nWalletUnlockTime);
-            MilliSleep(nToSleep);
-            ENTER_CRITICAL_SECTION(cs_nWalletUnlockTime);
-
-        } while(1);
-
-        if (nWalletUnlockTime)
-        {
-            nWalletUnlockTime = 0;
-            pwalletMain->Lock();
-        }
-    }
-    else
-    {
-        if (nWalletUnlockTime < nMyWakeTime)
-            nWalletUnlockTime = nMyWakeTime;
-    }
-
-    LEAVE_CRITICAL_SECTION(cs_nWalletUnlockTime);
-
-    delete (int64*)parg;
+    LOCK(cs_nWalletUnlockTime);
+    nWalletUnlockTime = 0;
+    pWallet->Lock();
 }
 
 Value walletpassphrase(const Array& params, bool fHelp)
@@ -1319,9 +1274,6 @@ Value walletpassphrase(const Array& params, bool fHelp)
     if (!pwalletMain->IsCrypted())
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletpassphrase was called.");
 
-    if (!pwalletMain->IsLocked())
-        throw JSONRPCError(RPC_WALLET_ALREADY_UNLOCKED, "Error: Wallet is already unlocked.");
-
     // Note that the walletpassphrase is stored in params[0] which is not mlock()ed
     SecureString strWalletPass;
     strWalletPass.reserve(100);
@@ -1339,9 +1291,12 @@ Value walletpassphrase(const Array& params, bool fHelp)
             "walletpassphrase <passphrase> <timeout>\n"
             "Stores the wallet decryption key in memory for <timeout> seconds.");
 
-    NewThread(ThreadTopUpKeyPool, NULL);
-    int64* pnSleepTime = new int64(params[1].get_int64());
-    NewThread(ThreadCleanWalletPassphrase, pnSleepTime);
+    pwalletMain->TopUpKeyPool();
+
+    int64 nSleepTime = params[1].get_int64();
+    LOCK(cs_nWalletUnlockTime);
+    nWalletUnlockTime = GetTime() + nSleepTime;
+    RPCRunLater("lockwallet", boost::bind(LockWallet, pwalletMain), nSleepTime);
 
     return Value::null;
 }

src/wallet.cpp

@@ -87,9 +87,6 @@ bool CWallet::AddCScript(const CScript& redeemScript)
 
 bool CWallet::Unlock(const SecureString& strWalletPassphrase)
 {
-    if (!IsLocked())
-        return false;
-
     CCrypter crypter;
     CKeyingMaterial vMasterKey;
 
@@ -100,7 +97,7 @@ bool CWallet::Unlock(const SecureString& strWalletPassphrase)
             if(!crypter.SetKeyFromPassphrase(strWalletPassphrase, pMasterKey.second.vchSalt, pMasterKey.second.nDeriveIterations, pMasterKey.second.nDerivationMethod))
                 return false;
             if (!crypter.Decrypt(pMasterKey.second.vchCryptedKey, vMasterKey))
-                return false;
+                continue; // try another master key
             if (CCryptoKeyStore::Unlock(vMasterKey))
                 return true;
         }