/* eurephiafw.c  --  Firewall interface loader for the eurephia module
 *
 *  GPLv2 - Copyright (C) 2008  David Sommerseth <dazo@users.sourceforge.net>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; version 2
 *  of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dlfcn.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/wait.h>

#include "eurephia_struct.h"
#include "eurephia_log.h"
#include "eurephiafw.h"
#include "eurephiafw_intf.h"
#include "eurephia_getsym.h"
#include "eurephia_nullsafe.h"
#include "eurephia_values.h"
#include "eurephiafw_helpers.h"

int eFW_unload(eurephiaCTX *ctx) {
        if( ctx == NULL ) {
                return 1;
        }

        if( ctx->eurephia_fw_intf != NULL ) {
                eurephia_log(ctx, LOG_INFO, 3, "Unloading eurephia firewall interface");
                dlclose(ctx->eurephia_fw_intf);
                ctx->eurephia_fw_intf = NULL;
                return 0;
        }
        return 1;
}


int eFW_load(eurephiaCTX *ctx, const char *intf) {
        if( (intf == NULL) || (strlen(intf) == 0) ) {
                eurephia_log(ctx, LOG_FATAL, 0, "No valid eurephia firewall interface indicated");
                return 0;
        }
        eurephia_log(ctx, LOG_INFO, 2, "Loading eurephia firewall interface: %s", intf);

        ctx->eurephia_fw_intf = dlopen(intf, RTLD_NOW);
        if( ctx->eurephia_fw_intf == NULL ) {
                eurephia_log(ctx, LOG_FATAL, 0, "Could not open the eurephia firewall interface (%s)", intf);
                eurephia_log(ctx, LOG_FATAL, 1, "dlopen error: %s", dlerror());
                return 0;
        }

        // Mandatory functions
        eFWinterfaceVersion = eGetSym(ctx, ctx->eurephia_fw_intf, "eFWinterfaceVersion");
        eFWinterfaceAPIversion = eGetSym(ctx, ctx->eurephia_fw_intf, "eFWinterfaceAPIversion");

        eurephia_log(ctx, LOG_INFO, 1, "Firewall interface loaded: %s (API version %i)",
                     eFWinterfaceVersion(), eFWinterfaceAPIversion());

        // Configure firewall interface functions
        switch( eFWinterfaceAPIversion() ) {
        default:
                eurephia_log(ctx, LOG_WARNING, 0,
                             "eurephia Firewall interface API is newer than what the running eurephia version is "
                             "familiar with.  Please consider to upgrade eurphia to take advantage of newer "
                             "features in the eurephiaDB driver.");

        case 1:
                eFW_RunFirewall = eGetSym(ctx, ctx->eurephia_fw_intf, "eFW_RunFirewall");
                break;

        }

        if( ctx->fatal_error > 0 ) {
                eurephia_log(ctx, LOG_FATAL, 0, "eurephia Firewall interface is not correctly initialised.  "
                             "eurephia authentication will not be available");
                eFW_unload(ctx);
                return 0;
        }
        return 1;
}

void eFW_StartFirewall(eurephiaCTX *ctx) {
        struct mq_attr mqattr;
        eurephiaCTX *shadowctx = NULL;
        char buf[1026], *fwdest = NULL;
        unsigned int prio;

        ctx->fwcfg = (eurephiaFWINTF *) malloc(sizeof(eurephiaFWINTF)+2);
        memset(ctx->fwcfg, 0, sizeof(eurephiaFWINTF)+2);

        // Create a fake eurephia context, just for logging
        shadowctx = (eurephiaCTX *) malloc(sizeof(eurephiaCTX)+2);
        memset(shadowctx, 0, sizeof(eurephiaCTX)+2);
        shadowctx->loglevel = ctx->loglevel;
        shadowctx->log = ctx->log;
        (*ctx->fwcfg).thrdata.ctx = shadowctx;

        (*ctx->fwcfg).thrdata.fw_command = strdup_nullsafe(eGet_value(ctx->dbc->config, "firewall_command"));
        if( (*ctx->fwcfg).thrdata.fw_command == NULL) {
                eurephia_log(ctx, LOG_PANIC, 0, "Could not find firewall_command in configuration.  "
                             "Firewall updates will not be available.");
                return;
        } else {
                eurephia_log(ctx, LOG_INFO, 1, "Using %s to update the firewall rules.",
                             (*ctx->fwcfg).thrdata.fw_command );
        }

        fwdest = eGet_value(ctx->dbc->config, "firewall_destination");
        if( fwdest == NULL ) {
                eurephia_log(ctx, LOG_PANIC, 0, "Could not find firewall_destination in configuration.  "
                             "Firewall updates will not be available.");
                return;
        } else {
                eurephia_log(ctx, LOG_INFO, 1, "Using '%s' as firewall rule for VPN accesses", fwdest);
        }

        ctx->fwcfg->fwblacklist = eGet_value(ctx->dbc->config, "firewall_blacklist_destination");
        if( ctx->fwcfg->fwblacklist != NULL ) {
                eurephia_log(ctx, LOG_INFO, 1,
                             "Blacklisted IP addresses will also be blocked in '%s'",
                             ctx->fwcfg->fwblacklist);
        }
        eurephia_log(ctx, LOG_INFO, 3, "Starting eurephia firewall interface");

        // Setup semaphores we need
        if( efwSetupSemaphores(ctx, &(*ctx->fwcfg).thrdata) == 0 ) {
                free_nullsafe(ctx->fwcfg->thrdata.fw_command);
                return;
        };

        // Setup a message queue
        if( efwSetupMessageQueue(ctx, &(*ctx->fwcfg).thrdata) == 0 ) {
                free_nullsafe(ctx->fwcfg);
                return;
        }

        // Make sure that these variables are not available in the child
        madvise(ctx, sizeof(eurephiaCTX), MADV_DONTFORK);

        // Start a new process (should run with root permissions) - which will do the firewall work
        if( (ctx->fwcfg->fwproc_pid = fork()) < 0 ) {
                eurephia_log(ctx, LOG_PANIC, 0,
                             "Could not fork out a child process for the firewall interface (%s)",
                             strerror(errno));
                return;
        }
        switch( ctx->fwcfg->fwproc_pid ) {
        case 0: // Child process
                eFW_RunFirewall(&(*ctx->fwcfg).thrdata);
                exit(-1); // If our child process exits abnormally.

        default: // Main process
                eurephia_log(ctx, LOG_INFO, 2, "Firewall updater process started (pid %i)",
                             ctx->fwcfg->fwproc_pid);
        }

        // Flush the message queue for old messages
        if( mq_getattr((*ctx->fwcfg).thrdata.msgq, &mqattr) == 0 ) {
                long i;

                memset(&buf, 0, 1026);
                if( mqattr.mq_curmsgs > 0 ) {
                        for( i = 0; i < mqattr.mq_curmsgs; i++ ) {
                                if( mq_receive((*ctx->fwcfg).thrdata.msgq, &buf[0], 1024, &prio) == -1 ) {
                                        eurephia_log(ctx, LOG_CRITICAL, 0,
                                                     "Error while emptying messages from queue: %s",
                                                     strerror(errno));
                                } else {
                                        DEBUG(ctx, 28, "Removed message on queue: %s", buf);
                                }
                        }
                }
                eurephia_log(ctx, LOG_INFO, 3, "Message queue for firewall updates is ready");
        } else {
                eurephia_log(ctx, LOG_FATAL, 0, "Could not retrieve message queue attributes (%s)",
                             strerror(errno));
        }

        // Indicate for the FW module that we are ready
        sem_post(ctx->fwcfg->thrdata.semp_master);

        // Waiting for the FW module to get ready
        DEBUG(ctx, 28, "eFW master is ready, waiting for the eFW worker to get ready");
        sem_wait(ctx->fwcfg->thrdata.semp_worker);
        eurephia_log(ctx, LOG_INFO, 2, "eFW interface initialised.");

	// Initialise the chain
        memset(&buf, 0, 1026);
        snprintf(buf, 1024, "I %s", fwdest);
        if( mq_send((*ctx->fwcfg).thrdata.msgq, buf, strlen(buf)+1, 1) == -1 ) {
                eurephia_log(ctx, LOG_ERROR, 0, "Could not request firewall initialisation of the %s chain: %s",
                             fwdest, strerror(errno));
        };
}

void eFW_StopFirewall(eurephiaCTX *ctx) {
        char buf[520], *fwdest = NULL;
        int childret = -1;

        if( ctx->fwcfg == NULL ) {
                return;
        }

        eurephia_log(ctx, LOG_INFO, 2, "Stopping eurephia firewall interface");

        // Flush the firewall chain before shutting down, to make sure
        // we don't unintentionally some accesses open
        fwdest = eGet_value(ctx->dbc->config, "firewall_destination");
        if( fwdest != NULL ) {
                memset(&buf, 0, 520);
                snprintf(buf, 512, "F %s", fwdest);
                if( mq_send((*ctx->fwcfg).thrdata.msgq, buf, strlen(buf)+1, 1) == -1 ) {
                        eurephia_log(ctx, LOG_CRITICAL, 0,
                                     "Could not request firewall flushing of the %s chain: %s",
                                     fwdest, strerror(errno));
                };
        } else {
                eurephia_log(ctx, LOG_CRITICAL, 0, "firewall_destination not set in config.  Will not flush "
                            "firewall before shutting down the firewall interface.");
        }


        // Send shutdown message to the firewall module process
        memset(&buf, 0, 520);
        snprintf(buf, 512, "FWSHUTDOWN%c", 0);
        if( mq_send((*ctx->fwcfg).thrdata.msgq, buf, 11, 1) == -1 ) {
                eurephia_log(ctx, LOG_PANIC, 0, "Could not initiate shutdown on eFW module: %s", strerror(errno));
                kill(ctx->fwcfg->fwproc_pid, SIGABRT);
        }

        // Wait for the firewall module process to finish
        if( waitpid(ctx->fwcfg->fwproc_pid, &childret, 0) != ctx->fwcfg->fwproc_pid ) {
                eurephia_log(ctx, LOG_PANIC, 0, "Failed to wait for eFW module process to quit: %s",
                             strerror(errno));
                kill(ctx->fwcfg->fwproc_pid, SIGABRT);
        }

        free_nullsafe((*ctx->fwcfg).thrdata.fw_command);
        free_nullsafe(ctx->fwcfg);
        eurephia_log(ctx, LOG_INFO, 2, "eurephia firewall interface is stopped");
}


int eFW_UpdateFirewall(eurephiaCTX *ctx, int mode,
                       const char *addr, const char *fwdest, const char *fwprofile) {
        char buf[1026];

        if( (*ctx->fwcfg).thrdata.fw_command == NULL ) {
                eurephia_log(ctx, LOG_FATAL, 0, "Function call: eFW_UpdateFirewall() -- "
                             "firewall_command is not configured. Firewall rules was not updated.");
                return 0;
        }

        memset(&buf, 0, 1026);
        switch( mode ) {
        case FWRULE_ADD:
                eurephia_log(ctx, LOG_INFO, 3, "Function call: eFW_UpdateFirewall(ctx, %s, '%s', '%s', '%s')",
                             "ADD", addr, fwdest, fwprofile);
                snprintf(buf, 1024, "A %s %s %s", addr, fwdest, fwprofile);
                mq_send((*ctx->fwcfg).thrdata.msgq, buf, strlen(buf)+1, 1);
                return 1;

        case FWRULE_DELETE:
                eurephia_log(ctx, LOG_INFO, 3, "Function call: eFW_UpdateFirewall(ctx, %s, '%s', '%s', '%s')",
                             "DELETE", addr, fwdest, fwprofile);
                snprintf(buf, 1024, "D %s %s %s", addr, fwdest, fwprofile);
                mq_send((*ctx->fwcfg).thrdata.msgq, buf, strlen(buf)+1, 1);
                return 1;

        case FWRULE_BLACKLIST:
                eurephia_log(ctx, LOG_INFO, 3, "Function call: eFW_UpdateFirewall(ctx, %s, '%s','%s', NULL)",
                             "BLACKLIST", addr, fwdest);
                snprintf(buf, 1024, "B %s %s", addr, fwdest);
                mq_send((*ctx->fwcfg).thrdata.msgq, buf, strlen(buf)+1, 1);
                return 1;

        default:
                eurephia_log(ctx, LOG_CRITICAL, 0,
                             "Function call: eFW_UpdateFirewall(ctx, %s, '%s') - UNKNOWN MODE", "(unknown)",
                             addr);
                return 0;
        }
}