Re-introduce alert functionality (#1470)

Re-introduce alert functionality removed from Bitcoin upstream

1 files changed, 246 insertions, 0 deletions

diff --git a/src/alert.cpp b/src/alert.cpp
new file mode 100644
index 000000000..21e4887cf
--- /dev/null
+++ b/src/alert.cpp
@@ -0,0 +1,246 @@
+// Copyright (c) 2010 Satoshi Nakamoto
+// Copyright (c) 2009-2015 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "alert.h"
+
+#include "clientversion.h"
+#include "net.h"
+#include "netmessagemaker.h"
+#include "pubkey.h"
+#include "timedata.h"
+#include "ui_interface.h"
+#include "util.h"
+#include "utilstrencodings.h"
+
+#include <stdint.h>
+#include <algorithm>
+#include <map>
+
+#include <boost/algorithm/string/classification.hpp>
+#include <boost/algorithm/string/replace.hpp>
+#include <boost/foreach.hpp>
+#include <boost/thread.hpp>
+
+using namespace std;
+
+map<uint256, CAlert> mapAlerts;
+CCriticalSection cs_mapAlerts;
+
+void CUnsignedAlert::SetNull()
+{
+    nVersion = 1;
+    nRelayUntil = 0;
+    nExpiration = 0;
+    nID = 0;
+    nCancel = 0;
+    setCancel.clear();
+    nMinVer = 0;
+    nMaxVer = 0;
+    setSubVer.clear();
+    nPriority = 0;
+
+    strComment.clear();
+    strStatusBar.clear();
+    strReserved.clear();
+}
+
+std::string CUnsignedAlert::ToString() const
+{
+    std::string strSetCancel;
+    BOOST_FOREACH(int n, setCancel)
+        strSetCancel += strprintf("%d ", n);
+    std::string strSetSubVer;
+    BOOST_FOREACH(const std::string& str, setSubVer)
+        strSetSubVer += "\"" + str + "\" ";
+    return strprintf(
+        "CAlert(\n"
+        "    nVersion     = %d\n"
+        "    nRelayUntil  = %d\n"
+        "    nExpiration  = %d\n"
+        "    nID          = %d\n"
+        "    nCancel      = %d\n"
+        "    setCancel    = %s\n"
+        "    nMinVer      = %d\n"
+        "    nMaxVer      = %d\n"
+        "    setSubVer    = %s\n"
+        "    nPriority    = %d\n"
+        "    strComment   = \"%s\"\n"
+        "    strStatusBar = \"%s\"\n"
+        ")\n",
+        nVersion,
+        nRelayUntil,
+        nExpiration,
+        nID,
+        nCancel,
+        strSetCancel,
+        nMinVer,
+        nMaxVer,
+        strSetSubVer,
+        nPriority,
+        strComment,
+        strStatusBar);
+}
+
+void CAlert::SetNull()
+{
+    CUnsignedAlert::SetNull();
+    vchMsg.clear();
+    vchSig.clear();
+}
+
+bool CAlert::IsNull() const
+{
+    return (nExpiration == 0);
+}
+
+uint256 CAlert::GetHash() const
+{
+    return Hash(this->vchMsg.begin(), this->vchMsg.end());
+}
+
+bool CAlert::IsInEffect() const
+{
+    return (GetAdjustedTime() < nExpiration);
+}
+
+bool CAlert::Cancels(const CAlert& alert) const
+{
+    if (!IsInEffect())
+        return false; // this was a no-op before 31403
+    return (alert.nID <= nCancel || setCancel.count(alert.nID));
+}
+
+bool CAlert::AppliesTo(int nVersion, const std::string& strSubVerIn) const
+{
+    // TODO: rework for client-version-embedded-in-strSubVer ?
+    return (IsInEffect() &&
+            nMinVer <= nVersion && nVersion <= nMaxVer &&
+            (setSubVer.empty() || setSubVer.count(strSubVerIn)));
+}
+
+bool CAlert::AppliesToMe() const
+{
+    return AppliesTo(PROTOCOL_VERSION, FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, std::vector<std::string>()));
+}
+
+bool CAlert::CheckSignature(const std::vector<unsigned char>& alertKey) const
+{
+    CPubKey key(alertKey);
+    if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
+        return error("CAlert::CheckSignature(): verify signature failed");
+
+    // Now unserialize the data
+    CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
+    sMsg >> *(CUnsignedAlert*)this;
+    return true;
+}
+
+CAlert CAlert::getAlertByHash(const uint256 &hash)
+{
+    CAlert retval;
+    {
+        LOCK(cs_mapAlerts);
+        map<uint256, CAlert>::iterator mi = mapAlerts.find(hash);
+        if(mi != mapAlerts.end())
+            retval = mi->second;
+    }
+    return retval;
+}
+
+bool CAlert::ProcessAlert(const std::vector<unsigned char>& alertKey, bool fThread)
+{
+    if (!CheckSignature(alertKey))
+        return false;
+    if (!IsInEffect())
+        return false;
+
+    // alert.nID=max is reserved for if the alert key is
+    // compromised. It must have a pre-defined message,
+    // must never expire, must apply to all versions,
+    // and must cancel all previous
+    // alerts or it will be ignored (so an attacker can't
+    // send an "everything is OK, don't panic" version that
+    // cannot be overridden):
+    int maxInt = std::numeric_limits<int>::max();
+    if (nID == maxInt)
+    {
+        if (!(
+                nExpiration == maxInt &&
+                nCancel == (maxInt-1) &&
+                nMinVer == 0 &&
+                nMaxVer == maxInt &&
+                setSubVer.empty() &&
+                nPriority == maxInt &&
+                strStatusBar == "URGENT: Alert key compromised, upgrade required"
+                ))
+            return false;
+    }
+
+    {
+        LOCK(cs_mapAlerts);
+        // Cancel previous alerts
+        for (map<uint256, CAlert>::iterator mi = mapAlerts.begin(); mi != mapAlerts.end();)
+        {
+            const CAlert& alert = (*mi).second;
+            if (Cancels(alert))
+            {
+                LogPrint("alert", "cancelling alert %d\n", alert.nID);
+                uiInterface.NotifyAlertChanged((*mi).first, CT_DELETED);
+                mapAlerts.erase(mi++);
+            }
+            else if (!alert.IsInEffect())
+            {
+                LogPrint("alert", "expiring alert %d\n", alert.nID);
+                uiInterface.NotifyAlertChanged((*mi).first, CT_DELETED);
+                mapAlerts.erase(mi++);
+            }
+            else
+                mi++;
+        }
+
+        // Check if this alert has been cancelled
+        BOOST_FOREACH(PAIRTYPE(const uint256, CAlert)& item, mapAlerts)
+        {
+            const CAlert& alert = item.second;
+            if (alert.Cancels(*this))
+            {
+                LogPrint("alert", "alert already cancelled by %d\n", alert.nID);
+                return false;
+            }
+        }
+
+        // Add to mapAlerts
+        mapAlerts.insert(make_pair(GetHash(), *this));
+        // Notify UI and -alertnotify if it applies to me
+        if(AppliesToMe())
+        {
+            uiInterface.NotifyAlertChanged(GetHash(), CT_NEW);
+            Notify(strStatusBar, fThread);
+        }
+    }
+
+    LogPrint("alert", "accepted alert %d, AppliesToMe()=%d\n", nID, AppliesToMe());
+    return true;
+}
+
+void
+CAlert::Notify(const std::string& strMessage, bool fThread)
+{
+    std::string strCmd = GetArg("-alertnotify", "");
+    if (strCmd.empty()) return;
+
+    // Alert text should be plain ascii coming from a trusted source, but to
+    // be safe we first strip anything not in safeChars, then add single quotes around
+    // the whole string before passing it to the shell:
+    std::string singleQuote("'");
+    std::string safeStatus = SanitizeString(strMessage);
+    safeStatus = singleQuote+safeStatus+singleQuote;
+    boost::replace_all(strCmd, "%s", safeStatus);
+
+    if (fThread)
+        boost::thread t(runCommand, strCmd); // thread runs free
+    else
+        runCommand(strCmd);
+}