SNFMilter/main.cpp

// main.cpp
//
// Copyright (C) 2007, ARM Research Labs, LLC.
// See www.armresearch.com for the copyright terms.
//
// This is the entry point for the SNF Milter.
// The main() function acquires the configuration file path, sets up the
// SNF engine, and passes control to the SNFMilter module via runSNFMilter().
//
// SNFMilter() makes use of the SNF engine until it is dismissed by the MTA via
// the appropriate libmilter call.
//
// While SNFMilter() is running, it will get new configuration data for each
// scan it is asked to perform. A configuration packet will be produced on
// demand by the main module. The main module will check the configuration once
// every second or so to make sure it has the correct current data. The
// configuration data structure is defined in SNFMilter.hpp.
//
// When the SNFMilter() function returns, the main() function closes down the
// SNF Engine and exits the program.

#include <errno.h>
#include <string.h>

#include <exception>
#include <iostream>
#include "SNFMulti.hpp"
#include "SNFMilter.hpp"

#include "config.h"

using namespace std;

const char* SNF_MILTER_VERSION = "SNFMilter " PACKAGE_VERSION " Build: " __DATE__ " " __TIME__;

static const string XCIShutdownResponse =
  "<snf><xci><server><response message=\'shutdown in progress\' code=\'1\'/></server></xci></snf>\n";

class XCIShutdownWatcher : public snfXCIServerCommandHandler {                  // Shutdown watcher.
  public:
    XCIShutdownWatcher(){}
    string processXCIRequest(snf_xci& X) {                                      // Here is how we process requests.
        if(0 == X.xci_server_command.find("shutdown")) {                        // If we find shutdown then
            smfi_stop();                                                        // Stop processing messages.
            return XCIShutdownResponse;                                         // respond with a message.
        }                                                                       // If we get some other request
        return XCIErrorResponse;                                                // return the error response.
    }
};

class SignalCatcher : public Thread {                                           // Class to catch a signal.
  private:
    sigset_t *MySignalSet;
    snf_RulebaseHandler *MyRulebase;
  public:
    SignalCatcher(sigset_t *Signal_Set, snf_RulebaseHandler* Rulebase) :        // Construct.
        MySignalSet(Signal_Set),                                                // Set of signals to catch.
        MyRulebase(Rulebase) {                                                  // Used for error logging.
        run();                                                                  // Start the thread.
    }        
    void myTask() {
        int ReceivedSignal;
        int Status = sigwait(MySignalSet, &ReceivedSignal);
        if (0 != Status) {
            // Log error.
            ostringstream Temp;
            Temp << "Error waiting for signal:  " << strerror(Status) << ".";
            MyRulebase->logThisError("Signal Catcher", 1, Temp.str());
            return;
        }
        smfi_stop();                                                            // Stop processing.
    }
};

const int CorrectARGc = 2;                                                      // How many arguments we expect.

void displayHelp() {                                                            // Display some help.
    cout
      << SNF_MILTER_VERSION << endl
      << "Copyright (C) 2007, ARM Research Labs, LLC (www.armresearch.com)" << endl
      << endl
      << "Use snfmilter <full path to configuration file>" << endl
      << "Example: /home/snfmilter/snfmilter /home/snfmilter/snf_milter.xml" << endl;
};

int main(int argc, char* argv[]) {

    // Get and check the command line arguments.

    if(CorrectARGc != argc) {                                                   // If our command line arguments
        displayHelp();                                                          // don't look right then display
        return 0;                                                               // our help screen.
    }

    bool DebugMode = false;                                                     // This will be our debug mode.
    string argv0(argv[0]);                                                      // Capture how we were called.
    if(
      string::npos != argv0.find("Debug") ||                                    // If we find "Debug" or
      string::npos != argv0.find("debug")                                       // "debug" in our command path
      ) {                                                                       // then we are in DebugMode.
        DebugMode = true;                                                       // Set the flag and tell the
        cout << "Debug Mode" << endl;                                           // watchers.
    }

    sigset_t SignalSet;                                                         // Set of signals to mask.
    SignalCatcher *SigCatcher;                                                  // Object to catch signal.

    try {                                                                       // Catch anything that breaks loose.

        int PthreadStatus;

        if ( (0 != sigemptyset(&SignalSet)) ||                                 // Mask signal for this thread and
                                                                               // all threads to be created.
             (0 != sigaddset(&SignalSet, ShutdownSignal)) ) {
            ostringstream Temp;

            Temp << "Error masking signal on startup:  " << strerror(errno) << ".";
            throw runtime_error(Temp.str());
        }
        PthreadStatus = pthread_sigmask(SIG_BLOCK, &SignalSet, 0);
        if (0 != PthreadStatus) {
            ostringstream Temp;
            Temp << "Error masking signal on startup (pthread_sigmask):  " << strerror(PthreadStatus) << ".";
            throw runtime_error(Temp.str());
        }

        snf_RulebaseHandler* MilterRulebase = new snf_RulebaseHandler();        // Allocate a rulebase handler.
        MilterRulebase->PlatformVersion(SNF_MILTER_VERSION);                    // Record our version identification.
        XCIShutdownWatcher ShutdownWatcher;                                     // Make a server shutdown processor
        MilterRulebase->XCIServerCommandHandler(ShutdownWatcher);               // and register it with the engine.
        MilterRulebase->open(argv[1], "", "");                                  // Open the rulebase.

        SNFMilterContextPool* MilterContexts =
          new SNFMilterContextPool(MilterRulebase);                             // Create the Milter Context Pool.

        SigCatcher = new SignalCatcher(&SignalSet, MilterRulebase);             // Create thread object to catch the signal.

        runLibMilter(MilterContexts, DebugMode);                                // Run the milter.

        ThreadState const &SigCatcherState = SigCatcher->MyState();
        if (Thread::ThreadStarted.Name == SigCatcherState.Name) {               // Is the signal catcher thread running?
            PthreadStatus = pthread_kill(SigCatcher->getMyThread(), ShutdownSignal);  // Yes.  Send it a signal.
            if (0 == PthreadStatus) {
                SigCatcher->join();                                             // Wait for signal catcher to complete.
            } else {
                ostringstream Temp;
                Temp << "Error terminating signal catcher:  " << strerror(PthreadStatus) << ".";
                throw runtime_error(Temp.str());
            }
        }

        delete MilterContexts;                                                  // Destroy the context pool.
        MilterContexts = 0;                                                     // Forget it.
        MilterRulebase->close();                                                // Close down the rulebase handler.
        delete MilterRulebase;                                                  // Destroy the rulebase.
        MilterRulebase = 0;                                                     // Forget it.
        delete SigCatcher;                                                      // Destroy the signal catcher.
        SigCatcher = 0;                                                         // Forget it.

    }                                                                           // That's all folks.

    catch(exception& e) {                                                       // Report any normal exceptions.
        cerr << "SNFMilter Exception: " << e.what() << endl;
    }
    catch(...) {                                                                // Report any unexpected exceptions.
        cerr << "SNFMilter Panic! Unknown Exception!" << endl;
    }

    return 0;                                                                   // Normally we return zero.
}