/* Copyright 2016 Alex 'AdUser' Z (ad_user@runbox.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include "common.h"
#include "log.h"
#include "config.h"
#include "appconfig.h"
#include "matches.h"
#include "ipaddr.h"
#include "event.h"
#include "source.h"
#include "filter.h"
#include "backend.h"
#include "statefile.h"
#include "mod-defs.h"
#include "jail.h"

#define DEFAULT_BANTIME  3600 /* in seconds, 1 hour */
#define DEFAULT_FINDTIME  300 /* in seconds, 5 min */
#define DEFAULT_EXPIRETIME 14400 /* in seconds, 4 hours */
#define DEFAULT_BANSCORE    50

f2b_jail_t *jails = NULL;

static f2b_jail_t defaults = {
  .bantime    = DEFAULT_BANTIME,
  .findtime   = DEFAULT_FINDTIME,
  .expiretime = DEFAULT_EXPIRETIME,
  .banscore   = DEFAULT_BANSCORE,
};

static struct opt_remap {
  const char *old;
  const char *new;
} deprecated[] = {
  { .old = "incr_bantime",   .new = "bantime_extend"  },
  { .old = "incr_findtime",  .new = "findtime_extend" },
  { .old = "maxretry",       .new = "banscore"        },
  { .old = NULL } /* end of list */
};

void
f2b_jail_parse_compound_value(const char *value, char *name, char *init) {
  size_t len = 0;
  char *p = NULL;

  if ((p = strchr(value, ':')) == NULL) {
    /* param = name */
    strlcpy(name, value, CONFIG_KEY_MAX);
    return;
  }

  /* param = name:init_string */
  len = p - value;
  if (len >= CONFIG_KEY_MAX) {
    f2b_log_msg(log_warn, "'name' part of value exceeds max length %d bytes: %s", CONFIG_KEY_MAX, value);
    return;
  }

  strlcpy(name, value, len + 1); /* ':' acts as '\0' */
  strlcpy(init, (p + 1), CONFIG_VAL_MAX);
  return;
}

bool
f2b_jail_set_param(f2b_jail_t *jail, const char *param, const char *value) {
  assert(jail != NULL);
  assert(param != NULL);
  assert(value != NULL);

  /* only 'safe to set at runtime' parameters here */
  if (strcmp(param, "enabled") == 0) {
    if (strcmp(value, "yes") == 0) {
      jail->flags |= JAIL_ENABLED;
    } else {
      jail->flags &= ~JAIL_ENABLED;
    }
    return true;
  }
  if (strcmp(param, "bantime") == 0) {
    jail->bantime = atoi(value);
    if (jail->bantime <= 0)
      jail->bantime = DEFAULT_BANTIME;
    return true;
  }
  if (strcmp(param, "findtime") == 0) {
    jail->findtime = atoi(value);
    if (jail->findtime <= 0)
      jail->findtime = DEFAULT_FINDTIME;
    return true;
  }
  if (strcmp(param, "expiretime") == 0) {
    jail->expiretime = atoi(value);
    if (jail->expiretime <= 0)
      jail->expiretime = DEFAULT_EXPIRETIME;
    return true;
  }
  if (strcmp(param, "banscore") == 0) {
    jail->banscore = atoi(value);
    if (jail->banscore == 0)
      jail->banscore = DEFAULT_BANSCORE;
    return true;
  }
  if (strcmp(param, "bantime_extend") == 0) {
    jail->bantime_extend = atof(value);
    return true;
  }
  if (strcmp(param, "findtime_extend") == 0) {
    jail->findtime_extend = atof(value);
    return true;
  }
  if (strcmp(param, "expiretime_extend") == 0) {
    jail->expiretime_extend = atof(value);
    return true;
  }
  for (struct opt_remap *opt = deprecated; opt->old != NULL; opt++) {
    if (strcmp(opt->old, param) != 0)
      continue;
    f2b_log_msg(log_warn, "jail '%s': param '%s' deprecated, use '%s' instead", jail->name, opt->old, opt->new);
    return true;
  }
  return false;
}

void
f2b_jail_apply_config(f2b_jail_t *jail, f2b_config_section_t *section) {
  f2b_config_param_t *param = NULL;

  assert(jail != NULL);
  assert(section != NULL);
  assert(section->type == t_jail || section->type == t_defaults);

  for (param = section->param; param != NULL; param = param->next) {
    if (strcmp(param->name, "state") == 0) {
      jail->flags |= JAIL_HAS_STATE;
      continue;
    }
    if (strcmp(param->name, "source") == 0) {
      f2b_jail_parse_compound_value(param->value, jail->source_name, jail->source_init);
      jail->flags |= JAIL_HAS_SOURCE;
      continue;
    }
    if (strcmp(param->name, "filter") == 0) {
      f2b_jail_parse_compound_value(param->value, jail->filter_name, jail->filter_init);
      jail->flags |= JAIL_HAS_FILTER;
      continue;
    }
    if (strcmp(param->name, "backend") == 0) {
      f2b_jail_parse_compound_value(param->value, jail->backend_name, jail->backend_init);
      jail->flags |= JAIL_HAS_BACKEND;
      continue;
    }
    if (f2b_jail_set_param(jail, param->name, param->value))
      continue;
    f2b_log_msg(log_warn, "jail '%s': unrecognized parameter: %s", jail->name, param->name);
  }

  return;
}

void
f2b_jail_set_defaults(f2b_config_section_t *section) {
  assert(section != NULL);
  assert(section->type == t_defaults);

  strlcpy(defaults.name, "default", sizeof(defaults.name)); /* can't init before */
  f2b_jail_apply_config(&defaults, section);

  return;
}

static void
f2b_jail_evt_match(const char *jail, f2b_ipaddr_t *addr, f2b_match_t *match) {
  char buf[EVENT_MAX] = "";
  snprintf(buf, sizeof(buf), "event=match jail=%s addr=%s stag=%08X ftag=%08X score=%d",
    jail, addr->text, match->stag, match->ftag, match->score);
  f2b_event_send(buf);
}

static void
f2b_jail_evt_ban(const char *jail, f2b_ipaddr_t *addr, int bantime) {
  char buf[EVENT_MAX] = "";
  snprintf(buf, sizeof(buf), "event=ban jail=%s addr=%s bantime=%u count=%lu", jail, addr->text, bantime, addr->bancount);
  f2b_event_send(buf);
}

static void
f2b_jail_evt_release(const char *jail, f2b_ipaddr_t *addr) {
  char buf[EVENT_MAX] = "";
  snprintf(buf, sizeof(buf), "event=release jail=%s addr=%s", jail, addr->text);
  f2b_event_send(buf);
}

bool
f2b_jail_ban(f2b_jail_t *jail, f2b_ipaddr_t *addr) {
  time_t bantime = 0;
  assert(jail != NULL);
  assert(addr != NULL);

  f2b_matches_flush(&addr->matches);
  addr->banned  = true;
  addr->banned_at = addr->lastseen;

  if (jail->bantime_extend > 0) {
    bantime = jail->bantime + (int) (addr->bancount * (jail->bantime * jail->bantime_extend));
  } else {
    bantime = jail->bantime;
  }
  addr->bancount++;
  addr->release_at = addr->banned_at + bantime;
  jail->stats.bans++;

  if (f2b_backend_check(jail->backend, addr->text)) {
    f2b_log_msg(log_warn, "jail '%s': ip %s was already banned", jail->name, addr->text);
    return true;
  }

  if (f2b_backend_ban(jail->backend, addr->text)) {
    f2b_jail_evt_ban(jail->name, addr, bantime);
    f2b_log_msg(log_note, "jail '%s': banned ip %s for %.1fhrs",
      jail->name, addr->text, (float) bantime / 3600);
    return true;
  }

  f2b_log_msg(log_error, "jail '%s': can't ban ip %s", jail->name, addr->text);
  return false;
}

bool
f2b_jail_unban(f2b_jail_t *jail, f2b_ipaddr_t *addr) {
  assert(jail != NULL);
  assert(addr != NULL);

  addr->banned  = false;
  addr->banned_at = 0;
  addr->release_at = 0;

  if (f2b_backend_unban(jail->backend, addr->text)) {
    f2b_jail_evt_release(jail->name, addr);
    f2b_log_msg(log_note, "jail '%s': released ip %s", jail->name, addr->text);
    return true;
  }

  f2b_log_msg(log_error, "jail '%s': can't release ip %s", jail->name, addr->text);
  return false;
}

f2b_jail_t *
f2b_jail_create(f2b_config_section_t *section) {
  f2b_jail_t *jail = NULL;

  assert(section != NULL);
  assert(section->type == t_jail);

  if ((jail = calloc(1, sizeof(f2b_jail_t))) == NULL) {
    f2b_log_msg(log_error, "calloc() for new jail failed");
    return NULL;
  }

  memcpy(jail, &defaults, sizeof(f2b_jail_t));
  strlcpy(jail->name, section->name, sizeof(jail->name));
  f2b_jail_apply_config(jail, section);

  if (jail->flags & JAIL_HAS_SOURCE)
    jail->source = f2b_source_create(jail->source_name, jail->source_init);
  if (jail->flags & JAIL_HAS_FILTER)
    jail->filter = f2b_filter_create(jail->filter_name, jail->filter_init);
  if (jail->flags & JAIL_HAS_BACKEND)
    jail->backend = f2b_backend_create(jail->backend_name, jail->backend_init);

  return jail;
}

f2b_jail_t *
f2b_jail_find(f2b_jail_t *list, const char *name) {
  assert(name != NULL);

  for (; list != NULL; list = list->next)
    if (strcmp(list->name, name) == 0)
      return list;

  return NULL;
}

void
f2b_jail_process(f2b_jail_t *jail) {
  f2b_match_t *match = NULL;
  f2b_ipaddr_t  *prev = NULL;
  f2b_ipaddr_t  *addr = NULL;
  unsigned int hostc = 0;
  char line[LOGLINE_MAX] = "";
  char matchbuf[IPADDR_MAX] = "";
  time_t findtime = 0;
  time_t expiretime = 0;
  time_t now = time(NULL);
  bool remove = false;
  bool reset = true; /* source reset */
  unsigned int stag, ftag;
  short int score;

  assert(jail != NULL);

  f2b_log_msg(log_debug, "jail '%s': processing", jail->name);

  f2b_backend_ping(jail->backend);
  
  while (jail->flags & JAIL_HAS_SOURCE) {
    if ((stag = f2b_source_next(jail->source, line, sizeof(line), reset)) <= 0)
      break; /* no more data */
    reset = false;
    if (jail->flags & JAIL_HAS_FILTER) {
      if ((ftag = f2b_filter_match(jail->filter, line, matchbuf, sizeof(matchbuf), &score)) == 0)
        continue; /* no match in filter */
    } else {
      /* without filter: 1) value always matches, 2) passed as-is */
      memcpy(matchbuf, line, sizeof(matchbuf));
      ftag = 0;
      score = MATCH_DEFSCORE;
    }
    /* find-or-create matched address in jail known hosts list */
    addr = f2b_addrlist_lookup(jail->ipaddrs, matchbuf);
    if (!addr) {
      addr = f2b_ipaddr_create(matchbuf);
      jail->ipaddrs = f2b_addrlist_append(jail->ipaddrs, addr);
      f2b_log_msg(log_debug, "jail '%s': found new ip %s", jail->name, matchbuf);
    }
    addr->lastseen = now;
    /* create, fill and append new match to found host history */
    jail->stats.matches++;
    if ((match = f2b_match_create(now)) == NULL) {
      f2b_log_msg(log_error, "can't allocate memory for new match");
      continue;
    }
    match->time = now;
    match->stag = stag;
    match->ftag = ftag;
    match->score = score;
    f2b_matches_prepend(&addr->matches, match);
    f2b_jail_evt_match(jail->name, addr, match);
    /* host is banned? */
    if (addr->banned) {
      if (addr->banned_at > (now - 5))
        f2b_log_msg(log_warn, "jail '%s': ip %s was already banned", jail->name, matchbuf);
      continue;
    }
    /* how deep should we look inside host's history? */
    findtime = jail->findtime + jail->findtime * (jail->findtime_extend * addr->bancount);
    f2b_matches_expire(&addr->matches, now - findtime - 600);
    /* ...so, check host score */
    score = f2b_matches_score(&addr->matches, findtime);
    f2b_log_msg(log_info, "jail '%s': new match for ip %s (%u/%u)",
      jail->name, matchbuf, score, jail->banscore);
    if (score < jail->banscore)
      continue; /* lucky bastard */
    /* else: score limit reached, ban ip */
    f2b_jail_ban(jail, addr);
    if (jail->flags & JAIL_HAS_STATE)
      jail->sfile->need_save = true;
  }  /* while(1) */

  for (addr = jail->ipaddrs, prev = NULL; addr != NULL; ) {
    remove = false;
    /* check release time */
    if (addr->banned && now > addr->release_at)
      f2b_jail_unban(jail, addr);
    /* check expiration */
    expiretime = (addr->lastseen >= addr->release_at)
      ? addr->lastseen
      : addr->release_at;
    expiretime += jail->expiretime;
    if (now > expiretime) {
      f2b_log_msg(log_info, "jail '%s': expired ip %s",
        jail->name, addr->text);
      remove = true;
    }
    /* list cleanup */
    if (!remove) {
      prev = addr, addr = addr->next;
      hostc++;
      continue;
    }
    /* remove from list */
    if (prev == NULL) {
      /* first item in list */
      jail->ipaddrs = addr->next;
      f2b_ipaddr_destroy(addr);
      addr = jail->ipaddrs;
    } else {
      /* somewhere in list */
      prev->next = addr->next;
      f2b_ipaddr_destroy(addr);
      addr = prev->next;
    }
  }
  jail->stats.hosts = hostc;

  if (jail->flags & JAIL_HAS_STATE && jail->sfile->need_save) {
    f2b_statefile_save(jail->sfile, jail->ipaddrs);
    jail->sfile->need_save = false;
  }

  return;
}

bool
f2b_jail_init(f2b_jail_t *jail, f2b_config_t *config) {
  f2b_config_section_t *section = NULL;

  assert(jail   != NULL);
  assert(config != NULL);

  if ((jail->flags & (JAIL_HAS_SOURCE | JAIL_HAS_BACKEND)) == 0) {
    f2b_log_msg(log_error, "jail '%s': misconfigured, at least source or backend must be set", jail->name);
    return false;
  }

  if (jail->flags & JAIL_HAS_STATE) {
    jail->sfile = f2b_statefile_create(appconfig.statedir_path, jail->name);
    if (jail->sfile == NULL) {
      f2b_log_msg(log_debug, "jail '%s': can't create statefile", jail->name);
      goto cleanup0;
    }
  }

  if (jail->flags & JAIL_HAS_SOURCE) {
    if ((section = f2b_config_section_find(config->sources, jail->source->name)) == NULL) {
      f2b_log_msg(log_error, "jail '%s': no source with name '%s'", jail->name, jail->source->name);
      goto cleanup1;
    }
    if (!f2b_source_init(jail->source, section)) {
      f2b_log_msg(log_error, "jail '%s': can't init source '%s' with %s", jail->name, jail->source->name, jail->source->init);
      goto cleanup1;
    }
  }

  if (jail->flags & JAIL_HAS_FILTER) {
    if ((section = f2b_config_section_find(config->filters, jail->filter->name)) == NULL) {
      f2b_log_msg(log_error, "jail '%s': no filter with name '%s'", jail->name, jail->filter->name);
      goto cleanup2;
    }
    if (!f2b_filter_init(jail->filter, section)) {
      f2b_log_msg(log_error, "jail '%s': no regexps loaded from '%s'", jail->name, jail->filter->init);
      goto cleanup2;
    }
  } else if (jail->source && jail->source->flags & MOD_NEED_FILTER) {
    f2b_log_msg(log_error, "jail '%s': source '%s' needs filter, but jail has no one", jail->name, jail->source->name);
    goto cleanup1;
  }

  if (!jail->backend) {
    f2b_log_msg(log_error, "jail '%s': missing 'backend' option", jail->name);
    goto cleanup3;
  }
  if ((section = f2b_config_section_find(config->backends, jail->backend->name)) == NULL) {
    f2b_log_msg(log_error, "jail '%s': no backend with name '%s'", jail->name, jail->backend->name);
    goto cleanup3;
  }
  if (!f2b_backend_init(jail->backend, section)) {
    f2b_log_msg(log_error, "jail '%s': can't init backend '%s' with %s",
      jail->name, jail->backend->name, jail->backend->init);
    goto cleanup3;
  }

  /* start all */
  if (jail->source && !f2b_source_start(jail->source)) {
    f2b_log_msg(log_warn, "jail '%s': source action 'start' failed", jail->name);
    goto cleanup3;
  }
  if (!f2b_backend_start(jail->backend)) {
    f2b_log_msg(log_warn, "jail '%s': backend action 'start' failed", jail->name);
    goto cleanup3;
  }

  jail->flags |= JAIL_CONFIGURED;
  f2b_log_msg(log_debug, "jail '%s' init complete", jail->name);

  return true;

  cleanup3:
  if (jail->backend) {
    f2b_backend_destroy(jail->backend);
    jail->backend = NULL;
  }
  cleanup2:
  if (jail->filter) {
    f2b_filter_destroy(jail->filter);
    jail->filter = NULL;
  }
  cleanup1:
  if (jail->source) {
    f2b_source_destroy(jail->source);
    jail->source = NULL;
  }
  cleanup0:
  return false;
}

bool
f2b_jail_start(f2b_jail_t *jail) {
  unsigned int hostc = 0;
  time_t now = time(NULL);
  time_t remains;

  assert(jail != NULL);

  if (jail->flags & JAIL_HAS_STATE)
    jail->ipaddrs = f2b_statefile_load(jail->sfile);

  /* addrlist cleanup */
  for (f2b_ipaddr_t *addr = jail->ipaddrs; addr != NULL; addr = addr->next) {
    hostc++;
    if (addr->banned && now >= addr->release_at)
      addr->banned = false;
  }
  jail->stats.hosts = hostc;

  /* actual ban restore */
  if (jail->flags & JAIL_HAS_BACKEND) {
    for (f2b_ipaddr_t *addr = jail->ipaddrs; addr != NULL; addr = addr->next) {
      if (!addr->banned)
        continue;
      if (f2b_backend_check(jail->backend, addr->text))
        continue; /* already banned or backend don't support check() */
      if (f2b_backend_ban(jail->backend, addr->text)) {
        remains = addr->release_at - now;
        f2b_log_msg(log_note, "jail '%s': restored ban of ip %s (%.1fhrs remain)",
          jail->name, addr->text, (float) remains / 3600);
      } else {
        f2b_log_msg(log_error, "jail '%s': can't ban ip %s", jail->name, addr->text);
      }
    }
  }

  f2b_log_msg(log_info, "jail '%s' started", jail->name);

  return true;
}

bool
f2b_jail_stop(f2b_jail_t *jail) {
  bool errors = false;

  assert(jail != NULL);

  f2b_log_msg(log_info, "jail '%s': gracefull shutdown", jail->name);

  if (jail->flags & JAIL_HAS_SOURCE) {
    if (!f2b_source_stop(jail->source)) {
      f2b_log_msg(log_error, "jail '%s': action 'stop' for source failed", jail->name);
      errors = true;
    }
    f2b_source_destroy(jail->source);
  }

  if (jail->flags & JAIL_HAS_FILTER) {
    f2b_filter_destroy(jail->filter);
  }

  if (jail->flags & JAIL_HAS_BACKEND) {
    for (f2b_ipaddr_t *addr = jail->ipaddrs; addr != NULL; addr = addr->next) {
      if (!addr->banned)
        continue;
      if (f2b_jail_unban(jail, addr))
        continue;
      errors = true;
    }
    if (!f2b_backend_stop(jail->backend)) {
      f2b_log_msg(log_error, "jail '%s': action 'stop' for backend failed", jail->name);
      errors = true;
    }
    f2b_backend_destroy(jail->backend);
  }
  f2b_addrlist_destroy(jail->ipaddrs);

  if (jail->flags & JAIL_HAS_STATE) {
    f2b_statefile_destroy(jail->sfile);
  }

  jail->flags &= ~JAIL_CONFIGURED;
  return errors;
}

void
f2b_jail_cmd_status(char *res, size_t ressize, f2b_jail_t *jail) {
  char buf[1024] = "";
  const char *fmt1 =
    "name: %s\n"
    "banscore: %d\n"
    "flags:\n"
    "  enabled: %s\n"
    "  state: %s\n"
    "  source: %s\n"
    "  filter: %s\n";
  const char *fmt2 =
    "times:\n"
    "  bantime: %.1f hrs (+%d%%)\n"
    "  findtime: %.1f min (+%d%%)\n"
    "  expiretime: %.1f hrs (+%d%%)\n";
  const char *fmt3 =
    "stats:\n"
    "  hosts: %d\n"
    "  matches: %d\n"
    "  bans: %d\n";

  assert(res  != NULL);
  assert(jail != NULL);

  snprintf(res, ressize, fmt1,
    jail->name, jail->banscore,
    jail->flags & JAIL_ENABLED     ? "yes" : "no",
    jail->flags & JAIL_HAS_STATE   ? "yes" : "no",
    jail->flags & JAIL_HAS_SOURCE  ? "yes" : "no",
    jail->flags & JAIL_HAS_FILTER  ? "yes" : "no"
  );
  snprintf(buf, sizeof(buf), fmt2,
    (float) jail->bantime    / 3600, (int) (jail->bantime_extend    * 100),
    (float) jail->findtime   /   60, (int) (jail->findtime_extend   * 100),
    (float) jail->expiretime / 3600, (int) (jail->expiretime_extend * 100)
  );
  strlcat(res, buf, ressize);
  snprintf(buf, sizeof(buf), fmt3,
    jail->stats.hosts,
    jail->stats.matches,
    jail->stats.bans
  );
  strlcat(res, buf, ressize);
}

void
f2b_jail_cmd_set(char *res, size_t ressize, f2b_jail_t *jail, const char *param, const char *value) {
  assert(res   != NULL);
  assert(jail  != NULL);
  assert(param != NULL);
  assert(value != NULL);

  if (f2b_jail_set_param(jail, param, value)) {
    strlcpy(res, "+ok\n", ressize);
    return;
  }
  snprintf(res, ressize, "-parameter not found: %s\n", param);
}

/**
 * @brief misc operations on ip in given jail
 * @param res  response buffer (don't change if no error)
 * @param ressize response buffer size
 * @param jail selected jail
 * @param op Type of operation: >0 - ban, 0 - status, <0 - unban
 * @param ip IP address
 */
void
f2b_jail_cmd_ip_xxx(char *res, size_t ressize, f2b_jail_t *jail, int op, const char *ip) {
  f2b_match_t *match = NULL;
  f2b_ipaddr_t *addr = NULL;
  bool ret = false;

  assert(res  != NULL);
  assert(jail != NULL);
  assert(ip   != NULL);

  if ((jail->flags & JAIL_HAS_BACKEND) == 0 && op != 0) {
    strlcpy(res, "-jail has no configured backend\n", ressize);
    return;
  }

  if ((addr = f2b_addrlist_lookup(jail->ipaddrs, ip)) == NULL) {
    /* address not found in list */
    if (op > 0) {
      /* ban */
      time_t now = time(NULL);
      if ((addr = f2b_ipaddr_create(ip)) == NULL) {
        snprintf(res, ressize, "-can't parse ip address: %s\n", ip);
        return;
      }
      addr->lastseen = now;
      match = f2b_match_create(now);
      f2b_matches_prepend(&addr->matches, match);
      f2b_matches_flush(&addr->matches);
      jail->ipaddrs = f2b_addrlist_append(jail->ipaddrs, addr);
      jail->stats.hosts++;
      if (jail->flags & JAIL_HAS_STATE)
        jail->sfile->need_save = true;
    } else {
      /* unban & status */
      snprintf(res, ressize, "-can't find ip '%s' in jail '%s'\n", ip, jail->name);
      return;
    }
  }

  if (op == 0) {
    f2b_ipaddr_status(addr, res, ressize);
    return;
  }
  if (op > 0) { ret = f2b_jail_ban  (jail, addr); }
  if (op < 0) { ret = f2b_jail_unban(jail, addr); }
  strlcpy(res, ret ? "+ok\n" : "-error\n", ressize);
  return;
}