#!/bin/bash

# Copyright 2014,2015,2016,2017,2018,2019,2020 Security Onion Solutions, LLC
#
# 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, either version 3 of the License, or
# (at your option) any later version.
#
# 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, see <http://www.gnu.org/licenses/>.
{%- set ISAIRGAP = salt['pillar.get']('global:airgap', 'False') %}

output_dir="/opt/so/saltstack/default/salt/strelka/rules"
mkdir -p $output_dir
repos="$output_dir/repos.txt"
ignorefile="$output_dir/ignore.txt"

deletecounter=0
newcounter=0
updatecounter=0

{% if ISAIRGAP is sameas true %}


clone_dir="/nsm/repo/rules/strelka"
repo_name="signature-base"
mkdir -p /opt/so/saltstack/default/salt/strelka/rules/signature-base

[ -f $clone_dir/LICENSE ] && cp $clone_dir/$repo_name/LICENSE $output_dir/$repo_name

# Copy over rules
for i in $(find $clone_dir/yara -name "*.yar*"); do
  rule_name=$(echo $i | awk -F '/' '{print $NF}')
  repo_sum=$(sha256sum $i | awk '{print $1}')

  # Check rules against those in ignore list -- don't copy if ignored.
  if ! grep -iq $rule_name $ignorefile; then
    existing_rules=$(find $output_dir/$repo_name/ -name $rule_name | wc -l)

    # For existing rules, check to see if they need to be updated, by comparing checksums
    if [ $existing_rules -gt 0 ];then
      local_sum=$(sha256sum $output_dir/$repo_name/$rule_name | awk '{print $1}')
      if [ "$repo_sum" != "$local_sum" ]; then
        echo "Checksums do not match!"
        echo "Updating $rule_name..."
        cp $i $output_dir/$repo_name;
        ((updatecounter++))
      fi
    else
      # If rule doesn't exist already, we'll add it
      echo "Adding new rule: $rule_name..."
      cp $i $output_dir/$repo_name
      ((newcounter++))
    fi
  fi;
done

# Check to see if we have any old rules that need to be removed
for i in $(find $output_dir/$repo_name -name "*.yar*" | awk -F '/' '{print $NF}'); do
  is_repo_rule=$(find $clone_dir -name "$i" | wc -l)
  if [ $is_repo_rule -eq 0 ]; then
    echo "Could not find $i in source $repo_name repo...removing from $output_dir/$repo_name..."
    rm $output_dir/$repo_name/$i
    ((deletecounter++))
  fi
done

echo "Done!"

  if [ "$newcounter" -gt 0 ];then
    echo "$newcounter new rules added."
  fi

  if [ "$updatecounter" -gt 0 ];then
    echo "$updatecounter rules updated."
  fi

  if [ "$deletecounter" -gt 0 ];then
    echo "$deletecounter rules removed because they were deprecated or don't exist in the source repo."
  fi

{% else %}

gh_status=$(curl -s -o /dev/null -w "%{http_code}" http://github.com)
clone_dir="/tmp"
if [ "$gh_status" == "200" ]  || [ "$gh_status" == "301" ]; then

  while IFS= read -r repo; do

    # Remove old repo if existing bc of previous error condition or unexpected disruption
    repo_name=`echo $repo | awk -F '/' '{print $NF}'`
    [ -d $repo_name ] && rm -rf $repo_name

    # Clone repo and make appropriate directories for rules

    git clone $repo $clone_dir/$repo_name
    echo "Analyzing rules from $clone_dir/$repo_name..."
    mkdir -p $output_dir/$repo_name
    [ -f $clone_dir/$repo_name/LICENSE ] && cp $clone_dir/$repo_name/LICENSE $output_dir/$repo_name

    # Copy over rules
    for i in $(find $clone_dir/$repo_name -name "*.yar*"); do
      rule_name=$(echo $i | awk -F '/' '{print $NF}')
      repo_sum=$(sha256sum $i | awk '{print $1}')

      # Check rules against those in ignore list -- don't copy if ignored.
      if ! grep -iq $rule_name $ignorefile; then
        existing_rules=$(find $output_dir/$repo_name/ -name $rule_name | wc -l)

        # For existing rules, check to see if they need to be updated, by comparing checksums
        if [ $existing_rules -gt 0 ];then
          local_sum=$(sha256sum $output_dir/$repo_name/$rule_name | awk '{print $1}')
          if [ "$repo_sum" != "$local_sum" ]; then
            echo "Checksums do not match!"
            echo "Updating $rule_name..."
            cp $i $output_dir/$repo_name;
            ((updatecounter++))
          fi
        else
          # If rule doesn't exist already, we'll add it
          echo "Adding new rule: $rule_name..."
          cp $i $output_dir/$repo_name
          ((newcounter++))
        fi
      fi;
    done

    # Check to see if we have any old rules that need to be removed
    for i in $(find $output_dir/$repo_name -name "*.yar*" | awk -F '/' '{print $NF}'); do
      is_repo_rule=$(find $clone_dir/$repo_name -name "$i" | wc -l)
      if [ $is_repo_rule -eq 0 ]; then
        echo "Could not find $i in source $repo_name repo...removing from $output_dir/$repo_name..."
        rm $output_dir/$repo_name/$i
        ((deletecounter++))
      fi
    done
    rm -rf $clone_dir/$repo_name
  done < $repos

  echo "Done!"

  if [ "$newcounter" -gt 0 ];then
    echo "$newcounter new rules added."
  fi

  if [ "$updatecounter" -gt 0 ];then
    echo "$updatecounter rules updated."
  fi

  if [ "$deletecounter" -gt 0 ];then
    echo "$deletecounter rules removed because they were deprecated or don't exist in the source repo."
  fi

else
  echo "Server returned $gh_status status code."
  echo "No connectivity to Github...exiting..."
  exit 1
fi
{%- endif -%}