/*

 * Copyright (C) 2019 OpenSIPS Solutions

 *

 * This file is part of opensips, a free SIP server.

 *

 * opensips 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; either version 2 of the License, or

 * (at your option) any later version

 *

 * opensips 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 <unistd.h>

#include <errno.h>

#include "mem/mem.h"

#include "globals.h"

#include "locking.h"

#include "rw_locking.h"

#include "daemonize.h"

#include "pt.h"

#include "route.h"

#include "reactor_defs.h"

#include "cfg_pp.h"

#include "cfg_reload.h"

extern FILE *yyin;

extern int yyparse();

#ifdef DEBUG_PARSER

extern int yydebug;

#endif

/* maximum number of milliseconds to wait for processes to get to final

 * conclusion over validating a script reloading */

#define MAX_PROC_RELOAD_WAIT 20000

enum proc_reload_status {

  RELOAD_NONE=0,        /* no reload going on */

  RELOAD_SENT,          /* reload cmd sent */

  RELOAD_RECEIVED,      /* reload cmd received by proc (load in progress)*/

  RELOAD_SUCCESS,       /* cfg reload succeded */

  RELOAD_FAILED         /* cfg reload failed */

  };

struct script_reload_ctx {

  gen_lock_t lock;

  rw_lock_t *rw_lock;

  unsigned int seq_no;

  unsigned int next_seq_no;

  str cfg_buf;

  enum proc_reload_status *proc_status;

};

int cfg_parse_only_routes = 0;

/* scripting routes reload context */

struct script_reload_ctx *srr_ctx = NULL;

/* if currently we run an older version of the cfg, resulting form a recent

 * reload - this just a santinel variable when (due async resume) we have to

 * go back and use the old script (which was used for triggering the async)

 * Of course, this is per process */

int _running_old_script = 0;

/* if we still keep the old/previous cfg (as a result of a recent reload)

 * this will stay on as time as we have in memory the old script. When the

 * old script is free, this will also be reset (also see the above comment) */

int _have_old_script = 0;

/* old/prev cfg - we may need to keep it in paralle with the new one in 

 * order to properly complete the ongoing async operatation */

static struct os_script_routes *prev_sr=NULL;

static struct os_script_routes *swap_bk = NULL;

void reload_swap_old_script(void)

{

  swap_bk = sroutes;

  sroutes = prev_sr;

}

void reload_swap_current_script(void)

{

  sroutes = swap_bk;

}

void reload_free_old_cfg(void)

{

  LM_ERR("finally removing the old/prev cfg\n");

  free_route_lists(prev_sr);

  prev_sr = NULL;

  _have_old_script = 0;

}

int init_script_reload(void)

{

  srr_ctx = (struct script_reload_ctx *)shm_malloc( sizeof(*srr_ctx) +

    counted_max_processes*sizeof(enum proc_reload_status) );

  if (srr_ctx==NULL) {

    LM_ERR("failed to shm allocate the script reload context\n");

    return -1;

  }

  memset( srr_ctx, 0, sizeof(*srr_ctx) +

    counted_max_processes*sizeof(enum proc_reload_status));

  srr_ctx->next_seq_no = 1;

  lock_init( &srr_ctx->lock );

  srr_ctx->rw_lock = lock_init_rw();

  if (srr_ctx->rw_lock==NULL) {

    LM_ERR("failed to create rw lock for script reload context\n");

    shm_free(srr_ctx);

    srr_ctx = NULL;

    return -1;

  }

  srr_ctx->proc_status = (enum proc_reload_status*)(srr_ctx + 1);

  return 0;

}

static inline void reset_script_reload_ctx(void)

{

  if (srr_ctx->cfg_buf.s)

    shm_free(srr_ctx->cfg_buf.s);

  srr_ctx->cfg_buf.s = NULL;

  srr_ctx->cfg_buf.len = 0;

  memset( srr_ctx->proc_status, 0,

    counted_max_processes*sizeof(enum proc_reload_status));

  /* this must be the last as it will allow the ctx reusage

   * for another reload */

  srr_ctx->seq_no = 0;

}

static inline void send_cmd_to_all_procs(ipc_rpc_f *rpc)

{

  int i;

  /* send it to all process with IPC and needing SCRIPT */

  for( i=1 ; i<counted_max_processes ; i++) {

    if ( (pt[i].flags&(OSS_PROC_NO_IPC|OSS_PROC_NEEDS_SCRIPT))==

    OSS_PROC_NEEDS_SCRIPT ) {

      /* set the status before sending, to avoid any race condition

       * with running the callback function */

      srr_ctx->proc_status[i] = RELOAD_SENT;

      if (i==process_no) {

        /* run line the cmd for the proc itself */

        rpc( process_no, (void*)(long)srr_ctx->seq_no);

      } else {

        if (ipc_send_rpc( i, rpc, (void*)(long)srr_ctx->seq_no)<0)

          srr_ctx->proc_status[i] = RELOAD_FAILED;

      }

    }

  }

}

static inline int check_status_of_all_procs(enum proc_reload_status min_status,

                      enum proc_reload_status max_status)

{

  int i;

  for( i=1 ; i<counted_max_processes ; i++) {

    if ( (pt[i].flags&(OSS_PROC_NO_IPC|OSS_PROC_NEEDS_SCRIPT))==

    OSS_PROC_NEEDS_SCRIPT ) {

        if (srr_ctx->proc_status[i]<min_status ||

        srr_ctx->proc_status[i]>max_status)

          return -1;

    }

  }

  return 1;

}

/* this is used only for debugging purposes */

static inline int list_status_of_all_procs(void)

{

  int i;

  for( i=1 ; i<counted_max_processes ; i++) {

    if ( (pt[i].flags&(OSS_PROC_NO_IPC|OSS_PROC_NEEDS_SCRIPT))==

    OSS_PROC_NEEDS_SCRIPT ) {

      LM_INFO("process %d [%d] reported status %d\n",

        i, pt[i].pid, srr_ctx->proc_status[i]);

    } else {

      LM_INFO("process %d [%d] not needing script \n", 

        i, pt[i].pid);

    }

  }

  return 1;

}

/* global, per process holder for a new script to be used (during reload).

   This is used to store the pending-to-use script during the validation

   step and the actual switching (to new script) step */

static struct os_script_routes *parsed_sr=NULL;

static void routes_reload_per_proc(int sender, void *param)

{

  struct os_script_routes *sr_bk;

  int seq_no = (int)(long)param;

  FILE *cfg;

  LM_DBG("reload cmd received in process %d, with seq no %d\n",

    process_no, seq_no);

  if (_have_old_script) {

    LM_ERR("cannot reload again as still having the previous cfg,"

      " retry later\n");

    srr_ctx->proc_status[process_no] = RELOAD_FAILED;

    return;

  }

  lock_start_read(srr_ctx->rw_lock);

  if (srr_ctx->seq_no==0 || srr_ctx->seq_no!=seq_no) {

    LM_INFO("dropping reload cmd due out of sequence reason\n");

    lock_stop_read(srr_ctx->rw_lock);

    return;

  }

  srr_ctx->proc_status[process_no] = RELOAD_RECEIVED;

  /* get a file stream from the buffer */

  cfg = fmemopen( srr_ctx->cfg_buf.s, srr_ctx->cfg_buf.len, "r");

  if (!cfg) {

    LM_ERR("failed to obtain file from cfg buffer\n");

    goto error;

  }

  /* get and set a new script routes holder (for new cfg) */

  if (parsed_sr) {

    /* probabaly left by mistake from a prev attempt ?? */

    free_route_lists(parsed_sr);

    pkg_free(parsed_sr);

  }

  parsed_sr = new_sroutes_holder( 1 );

  if (parsed_sr==NULL) {

    LM_ERR("failed to allocate a new script routes holder\n");

    fclose(cfg);

    goto error;

  }

  sr_bk = sroutes;

  sroutes = parsed_sr;

  /* parse, but only the routes */

  cfg_parse_only_routes = 1;

  yyin = cfg;

  if (yyparse() != 0 || cfg_errors) {

    LM_ERR("bad config file (%d errors)\n", cfg_errors);

    fclose(cfg);

    goto error;

  }

  fclose(cfg);

  cfg_parse_only_routes = 0;

  if (fix_rls()<0) {

    LM_ERR("fixing routes failed, abording\n");

    goto error;

  }

  sroutes = sr_bk;

  /* keep the parsed routes, waiting for the confirmation to switch */

  srr_ctx->proc_status[process_no] = RELOAD_SUCCESS;

  lock_stop_read(srr_ctx->rw_lock);

  LM_INFO("process successfully parsed new cfg (seq %d)\n",seq_no);

  return;

error:

  srr_ctx->proc_status[process_no] = RELOAD_FAILED;

  lock_stop_read(srr_ctx->rw_lock);

  if (parsed_sr) {

    free_route_lists(parsed_sr);

    pkg_free(parsed_sr);

    parsed_sr = NULL;

  }

  return;

}

static void routes_switch_per_proc(int sender, void *param)

{

  int seq_no = (int)(long)param;

  LM_DBG("swich cmd received in process %d, with seq no %d\n",

    process_no, seq_no);

  if (srr_ctx->seq_no!=0 && srr_ctx->seq_no!=seq_no) {

    LM_INFO("dropping switch cmd due out of sequence reason\n");

    if (parsed_sr) free_route_lists(parsed_sr);

    parsed_sr = NULL;

    return;

  }

  /* handle the async fd - mark them and see if we have any; if yes, 

   * then we need to keep the previous cfg until all the async are done */

  reactor_set_app_flag( F_SCRIPT_ASYNC, REACTOR_RELOAD_TAINTED_FLAG);

  reactor_set_app_flag(     F_FD_ASYNC, REACTOR_RELOAD_TAINTED_FLAG);

  reactor_set_app_flag( F_LAUNCH_ASYNC, REACTOR_RELOAD_TAINTED_FLAG);

  if (reactor_check_app_flag(REACTOR_RELOAD_TAINTED_FLAG)) {

    /* we do have onlgoing aync fds */

    LM_DBG("keeping previous cfg until all ongoing async complete\n");

    prev_sr = sroutes;

    _have_old_script = 1;

  } else {

    /* we can get rid of the script right away*/

    LM_DBG("no ongoing async, freeing the previous cfg\n");

    free_route_lists(sroutes);

    prev_sr = NULL;

    _have_old_script = 0;

  }

  /* swap the old route set with the new parsed set */

  sroutes = parsed_sr;

  parsed_sr = NULL;

  /* update all the ref to script routes */

  update_all_script_route_refs();

  print_script_route_refs();

}

/* This is the trigger point for script reloading

 */

int reload_routing_script(void)

{

  struct os_script_routes *sr, *sr_bk;

  char * curr_wdir=NULL;

  str cfg_buf={NULL,0};

  int cnt_sleep, ret;

  /* one reload at a time */

  lock_get( &srr_ctx->lock );

  if (srr_ctx->seq_no!=0) {

    LM_INFO("Reload already in progress, cannot start a new one\n");

    lock_release( &srr_ctx->lock );

    return -1;

  }

  srr_ctx->seq_no = srr_ctx->next_seq_no++;

  lock_release( &srr_ctx->lock );

  sr = new_sroutes_holder( 0 );

  if (sr==NULL) {

    LM_ERR("failed to allocate a new script routes holder\n");

    goto error;

  }

  LM_INFO("reparsing routes from <%s> file\n",cfg_file);

  sr_bk = sroutes;

  sroutes = sr;

  /* parse, but only the routes */

  cfg_parse_only_routes = 1;

  /* switch to the startup working dir, to be sure the file pathname 

   * (as given at startup via cli) still match */

  if (startup_wdir) {

    if ( (curr_wdir=getcwd(NULL,0))==NULL) {

      LM_ERR("failed to determin the working dir %d/%s\n", errno,

        strerror(errno));

      goto error;

    }

    if (chdir(startup_wdir)<0){

      LM_CRIT("Cannot chdir to %s: %s\n", startup_wdir, strerror(errno));

      goto error;

    }

  }

  ret = parse_opensips_cfg( cfg_file, preproc, &cfg_buf);

  cfg_parse_only_routes = 0;

  /* revert to the original working dir */

  if (curr_wdir) {

    if (chdir(curr_wdir)<0){

      LM_CRIT("Cannot chdir to %s: %s\n", curr_wdir, strerror(errno));

    }

    free(curr_wdir);

    curr_wdir=NULL;

  }

  if (ret<0) {

    LM_ERR("parsing failed, abording\n");

    goto error;

  }

  LM_INFO("fixing the loaded routes\n");

  if (fix_rls()<0) {

    LM_ERR("fixing routes failed, abording\n");

    goto error;

  }

  /* trigger module's validation functions to check if the reload of this 

   * new route set is "approved" */

  if (!modules_validate_reload()) {

    LM_ERR("routes validation by modules failed, abording reload. "

      "OpenSIPS restart is recomended to deploy the new script\n");

    goto error;

  }

  /* we do not need the cfg, so free it and restore previous set of routes */

  sroutes = sr_bk;

  free_route_lists(sr);

  pkg_free(sr);

  sr = NULL;

  LM_DBG("new routes are valid and approved, push it to all procs\n");

  if (shm_nt_str_dup( &srr_ctx->cfg_buf, &cfg_buf)<0) {

    LM_ERR("failed to shmem'ize the cfg buffer, abording\n");

    goto error;

  }

  /* we do not need the local cfg buffer anymore */

  free( cfg_buf.s );

  cfg_buf.s = NULL;

  cfg_buf.len = 0;

  /* send the script for parse and validation to all procs */

  send_cmd_to_all_procs( routes_reload_per_proc );

  LM_DBG("reload triggered into all processes, waiting...\n");

  /* wait until all the processes validate (or not) the new cfg */

  cnt_sleep = 0;

  while ( (cnt_sleep++)<MAX_PROC_RELOAD_WAIT &&

  check_status_of_all_procs( RELOAD_SUCCESS, RELOAD_FAILED)==-1)

    usleep(1000);

  LM_DBG("done with waiting after %d miliseconds\n",cnt_sleep);

  /* done with waiting -> check what happened so far, but be sure all

   * procs are not during a reload validation (in progress) */

  lock_start_write(srr_ctx->rw_lock);

  /* no other proc is doing script validation anymore,

   * so recheck the status */

  if (check_status_of_all_procs( RELOAD_SUCCESS, RELOAD_SUCCESS)!=1) {

    LM_INFO("not all processes managed to load the new script, "

      "aborting the reload\n");

    list_status_of_all_procs( );

    /* some processes failed with the reload - setting an out-of-order

     * sequence number will prevent any potential process waiting to 

     * start the reload to actually do it */

    srr_ctx->seq_no = INT_MAX;

    /* if the script was succesfully loaded by some procs, it will

     * be freed upon next reload attempt due sequence number */

    lock_stop_write(srr_ctx->rw_lock);

    goto error;

  }

  LM_DBG("all procs successfully reloaded, send the switch cmd\n");

  send_cmd_to_all_procs( routes_switch_per_proc );

  register_route_timers();

  /* ready for a new reload :) */

  reset_script_reload_ctx();

  lock_stop_write(srr_ctx->rw_lock);

  return 0;

error:

  /* allow other reloads to be triggered */

  reset_script_reload_ctx();

  /* do cleanup */

  if (curr_wdir) free(curr_wdir);

  if (sr) {

    free_route_lists(sr);

    pkg_free(sr);

    sroutes = sr_bk;

  }

  if (cfg_buf.s)

    free(cfg_buf.s);

  return -1;

}