#!/bin/sh
#
# Script to upgrade Libreswan on CentOS and RHEL
#
# Copyright (C) 2016-2017 Lin Song <linsongui@gmail.com>
#
# This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
# Unported License: http://creativecommons.org/licenses/by-sa/3.0/
#
# Attribution required: please include my name in any derivative and let me
# know how you have improved it!

# Check https://libreswan.org for the latest version
swan_ver=3.21

### DO NOT edit below this line ###

export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

exiterr()  { echo "Error: $1" >&2; exit 1; }
exiterr2() { echo "Error: 'yum install' failed." >&2; exit 1; }

if ! grep -qs -e "release 6" -e "release 7" /etc/redhat-release; then
  exiterr "This script only supports CentOS/RHEL 6 and 7."
fi

if [ -f /proc/user_beancounters ]; then
  exiterr "This script does not support OpenVZ VPS."
fi

if [ "$(id -u)" != 0 ]; then
  exiterr "Script must be run as root. Try 'sudo sh $0'"
fi

if [ -z "$swan_ver" ]; then
  exiterr "Libreswan version 'swan_ver' not specified."
fi

if ! /usr/local/sbin/ipsec --version 2>/dev/null | grep -q "Libreswan"; then
  exiterr "This script requires Libreswan already installed."
fi

if /usr/local/sbin/ipsec --version 2>/dev/null | grep -qF "$swan_ver"; then
  echo "You already have Libreswan version $swan_ver installed! "
  echo "If you continue, the same version will be re-installed."
  echo
  printf "Do you wish to continue anyway? [y/N] "
  read -r response
  case $response in
    [yY][eE][sS]|[yY])
      echo
      ;;
    *)
      echo "Aborting."
      exit 1
      ;;
  esac
fi

clear

cat <<EOF
Welcome! This script will build and install Libreswan $swan_ver on your server.
Additional packages required for Libreswan compilation will also be installed.

This is intended for use on servers running an older version of Libreswan.

EOF

cat <<'EOF'
IMPORTANT NOTES:

Libreswan versions 3.19 and newer require some configuration changes.
This script will make the following changes to your /etc/ipsec.conf:

Replace this line:
  auth=esp
with the following:
  phase2=esp

Replace this line:
  forceencaps=yes
with the following:
  encapsulation=yes

Consolidate VPN ciphers for "ike=" and "phase2alg=".
Re-add "MODP1024" to the list of allowed "ike=" ciphers,
which was removed from the defaults in Libreswan 3.19.

Your other VPN configuration files will not be modified.

EOF

printf "Do you wish to continue? [y/N] "
read -r response
case $response in
  [yY][eE][sS]|[yY])
    echo
    echo "Please be patient. Setup is continuing..."
    echo
    ;;
  *)
    echo "Aborting."
    exit 1
    ;;
esac

# Create and change to working dir
mkdir -p /opt/src
cd /opt/src || exiterr "Cannot enter /opt/src."

# Install Wget
yum -y install wget || exiterr2

# Add the EPEL repository
yum -y install epel-release || exiterr2

# Install necessary packages
yum -y install nss-devel nspr-devel pkgconfig pam-devel \
  libcap-ng-devel libselinux-devel \
  curl-devel flex bison gcc make \
  fipscheck-devel unbound-devel xmlto || exiterr2

# Install libevent2 and systemd-devel
if grep -qs "release 6" /etc/redhat-release; then
  yum -y remove libevent-devel
  yum -y install libevent2-devel || exiterr2
else
  yum -y install libevent-devel systemd-devel || exiterr2
fi

# Compile and install Libreswan
swan_file="libreswan-$swan_ver.tar.gz"
swan_url1="https://github.com/libreswan/libreswan/archive/v$swan_ver.tar.gz"
swan_url2="https://download.libreswan.org/$swan_file"
if ! { wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url1" || wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url2"; }; then
  exiterr "Cannot download Libreswan source."
fi
/bin/rm -rf "/opt/src/libreswan-$swan_ver"
tar xzf "$swan_file" && /bin/rm -f "$swan_file"
cd "libreswan-$swan_ver" || exiterr "Cannot enter Libreswan source dir."
cat > Makefile.inc.local <<'EOF'
WERROR_CFLAGS =
USE_DNSSEC = false
EOF
make -s programs && make -s install

# Verify the install and clean up
cd /opt/src || exiterr "Cannot enter /opt/src."
/bin/rm -rf "/opt/src/libreswan-$swan_ver"
if ! /usr/local/sbin/ipsec --version 2>/dev/null | grep -qF "$swan_ver"; then
  exiterr "Libreswan $swan_ver failed to build."
fi

# Restore SELinux contexts
restorecon /etc/ipsec.d/*db 2>/dev/null
restorecon /usr/local/sbin -Rv 2>/dev/null
restorecon /usr/local/libexec/ipsec -Rv 2>/dev/null

# Update ipsec.conf for Libreswan 3.19 and newer
IKE_NEW="  ike=3des-sha1,3des-sha2,aes-sha1,aes-sha1;modp1024,aes-sha2,aes-sha2;modp1024,aes256-sha2_512"
PHASE2_NEW="  phase2alg=3des-sha1,3des-sha2,aes-sha1,aes-sha2,aes256-sha2_512"
sed -i".old-$(date +%Y-%m-%d-%H:%M:%S)" \
    -e "s/^[[:space:]]\+auth=esp\$/  phase2=esp/" \
    -e "s/^[[:space:]]\+forceencaps=yes\$/  encapsulation=yes/" \
    -e "s/^[[:space:]]\+ike=.\+\$/$IKE_NEW/" \
    -e "s/^[[:space:]]\+phase2alg=.\+\$/$PHASE2_NEW/" /etc/ipsec.conf

# Restart IPsec service
service ipsec restart

echo
echo "Libreswan $swan_ver was installed successfully! "
echo

exit 0