-alertnotify=<cmd>

Runs a shell command when an AppliesToMe() alert is received.
%s in the <cmd> string is replaced with the alert.strStatusBar
message.

src/alert.cpp

@@ -2,6 +2,9 @@
 // Alert system
 //
 
+#include <algorithm>
+#include <boost/algorithm/string/classification.hpp>
+#include <boost/algorithm/string/replace.hpp>
 #include <boost/foreach.hpp>
 #include <map>
 
@@ -165,7 +168,7 @@ CAlert CAlert::getAlertByHash(const uint256 &hash)
     return retval;
 }
 
-bool CAlert::ProcessAlert()
+bool CAlert::ProcessAlert(bool fThread)
 {
     if (!CheckSignature())
         return false;
@@ -229,9 +232,35 @@ bool CAlert::ProcessAlert()
 
         // Add to mapAlerts
         mapAlerts.insert(make_pair(GetHash(), *this));
-        // Notify UI if it applies to me
+        // Notify UI and -alertnotify if it applies to me
         if(AppliesToMe())
+        {
             uiInterface.NotifyAlertChanged(GetHash(), CT_NEW);
+            std::string strCmd = GetArg("-alertnotify", "");
+            if (!strCmd.empty())
+            {
+                // 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("'");
+                // safeChars chosen to allow simple messages/URLs/email addresses, but avoid anything
+                // even possibly remotely dangerous like & or >
+                std::string safeChars("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890 .,;_/:?@");
+                std::string safeStatus;
+                for (std::string::size_type i = 0; i < strStatusBar.size(); i++)
+                {
+                    if (safeChars.find(strStatusBar[i]) != std::string::npos)
+                        safeStatus.push_back(strStatusBar[i]);
+                }
+                safeStatus = singleQuote+safeStatus+singleQuote;
+                boost::replace_all(strCmd, "%s", safeStatus);
+
+                if (fThread)
+                    boost::thread t(runCommand, strCmd); // thread runs free
+                else
+                    runCommand(strCmd);
+            }
+        }
     }
 
     printf("accepted alert %d, AppliesToMe()=%d\n", nID, AppliesToMe());

src/alert.h

@@ -91,7 +91,7 @@ public:
     bool AppliesToMe() const;
     bool RelayTo(CNode* pnode) const;
     bool CheckSignature() const;
-    bool ProcessAlert();
+    bool ProcessAlert(bool fThread = true);
 
     /*
      * Get copy of (active) alert object by hash. Returns a null alert if it is not found.

src/init.cpp

@@ -301,6 +301,7 @@ std::string HelpMessage()
         "  -rpcconnect=<ip>       " + _("Send commands to node running on <ip> (default: 127.0.0.1)") + "\n" +
         "  -blocknotify=<cmd>     " + _("Execute command when the best block changes (%s in cmd is replaced by block hash)") + "\n" +
         "  -walletnotify=<cmd>    " + _("Execute command when a wallet transaction changes (%s in cmd is replaced by TxID)") + "\n" +
+        "  -alertnotify=<cmd>     " + _("Execute command when a relevant alert is received (%s in cmd is replaced by message)") + "\n" +
         "  -upgradewallet         " + _("Upgrade wallet to latest format") + "\n" +
         "  -keypool=<n>           " + _("Set key pool size to <n> (default: 100)") + "\n" +
         "  -rescan                " + _("Rescan the block chain for missing wallet transactions") + "\n" +

src/test/alert_tests.cpp

@@ -4,13 +4,12 @@
 
 #include <boost/foreach.hpp>
 #include <boost/test/unit_test.hpp>
+#include <fstream>
 
 #include "alert.h"
 #include "serialize.h"
 #include "util.h"
 
-BOOST_AUTO_TEST_SUITE(Alert_tests)
-
 #if 0
 //
 // alertTests contains 7 alerts, generated with this code:
@@ -39,30 +38,40 @@ BOOST_AUTO_TEST_SUITE(Alert_tests)
     SignAndSave(alert, "test/alertTests");
 
     alert.setSubVer.clear();
-    alert.nID = 2;
+    ++alert.nID;
     alert.nCancel = 1;
+    alert.nPriority = 100;
     alert.strStatusBar  = "Alert 2, cancels 1";
     SignAndSave(alert, "test/alertTests");
 
     alert.nExpiration += 60;
+    ++alert.nID;
     SignAndSave(alert, "test/alertTests");
 
+    ++alert.nID;
     alert.nMinVer = 11;
     alert.nMaxVer = 22;
     SignAndSave(alert, "test/alertTests");
 
+    ++alert.nID;
     alert.strStatusBar  = "Alert 2 for Satoshi 0.1.0";
     alert.setSubVer.insert(std::string("/Satoshi:0.1.0/"));
     SignAndSave(alert, "test/alertTests");
+
+    ++alert.nID;
+    alert.nMinVer = 0;
+    alert.nMaxVer = 999999;
+    alert.strStatusBar  = "Evil Alert'; /bin/ls; echo '";
+    alert.setSubVer.clear();
+    SignAndSave(alert, "test/alertTests");
 }
 #endif
 
-
-std::vector<CAlert>
-read_alerts(const std::string& filename)
+struct ReadAlerts
 {
-    std::vector<CAlert> result;
-
+    ReadAlerts()
+    {
+        std::string filename("alertTests");
         namespace fs = boost::filesystem;
         fs::path testFile = fs::current_path() / "test" / "data" / filename;
 #ifdef TEST_DATA_DIR
@@ -72,31 +81,46 @@ read_alerts(const std::string& filename)
         }
 #endif
         FILE* fp = fopen(testFile.string().c_str(), "rb");
-    if (!fp) return result;
+        if (!fp) return;
 
 
         CAutoFile filein = CAutoFile(fp, SER_DISK, CLIENT_VERSION);
-    if (!filein) return result;
+        if (!filein) return;
 
         try {
             while (!feof(filein))
             {
                 CAlert alert;
                 filein >> alert;
-            result.push_back(alert);
+                alerts.push_back(alert);
             }
         }
         catch (std::exception) { }
+    }
+    ~ReadAlerts() { }
+
+    static std::vector<std::string> read_lines(boost::filesystem::path filepath)
+    {
+        std::vector<std::string> result;
+
+        std::ifstream f(filepath.string().c_str());
+        std::string line;
+        while (std::getline(f,line))
+            result.push_back(line);
 
         return result;
-}
+    }
+
+    std::vector<CAlert> alerts;
+};
+
+BOOST_FIXTURE_TEST_SUITE(Alert_tests, ReadAlerts)
+
 
 BOOST_AUTO_TEST_CASE(AlertApplies)
 {
     SetMockTime(11);
 
-    std::vector<CAlert> alerts = read_alerts("alertTests");
-
     BOOST_FOREACH(const CAlert& alert, alerts)
     {
         BOOST_CHECK(alert.CheckSignature());
@@ -129,4 +153,33 @@ BOOST_AUTO_TEST_CASE(AlertApplies)
     SetMockTime(0);
 }
 
+
+// This uses sh 'echo' to test the -alertnotify function, writing to a
+// /tmp file. So skip it on Windows:
+#ifndef WIN32
+BOOST_AUTO_TEST_CASE(AlertNotify)
+{
+    SetMockTime(11);
+
+    boost::filesystem::path temp = GetTempPath() / "alertnotify.txt";
+    boost::filesystem::remove(temp);
+
+    mapArgs["-alertnotify"] = std::string("echo %s >> ") + temp.string();
+
+    BOOST_FOREACH(CAlert alert, alerts)
+        alert.ProcessAlert(false);
+
+    std::vector<std::string> r = read_lines(temp);
+    BOOST_CHECK_EQUAL(r.size(), 4u);
+    BOOST_CHECK_EQUAL(r[0], "Alert 1");
+    BOOST_CHECK_EQUAL(r[1], "Alert 2, cancels 1");
+    BOOST_CHECK_EQUAL(r[2], "Alert 2, cancels 1");
+    BOOST_CHECK_EQUAL(r[3], "Evil Alert; /bin/ls; echo "); // single-quotes should be removed
+
+    boost::filesystem::remove(temp);
+
+    SetMockTime(0);
+}
+#endif
+
 BOOST_AUTO_TEST_SUITE_END()