#!/bin/sh
#
# Script to upgrade Libreswan on CentOS and RHEL
#
# Copyright (C) 2016-2018 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!

# Specify which Libreswan version to install. See: https://libreswan.org
SWAN_VER=3.22

### 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() { exiterr "'yum install' failed."; }

vpnupgrade() {

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 "OpenVZ VPS is not supported."
fi

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

case "$SWAN_VER" in
  3.19|3.2[01235])
    /bin/true
    ;;
  *)
    exiterr "Libreswan version '$SWAN_VER' is not supported."
    ;;
esac

ipsec_ver="$(/usr/local/sbin/ipsec --version 2>/dev/null)"
ipsec_ver_short="$(printf '%s' "$ipsec_ver" | sed -e 's/Linux Libreswan/Libreswan/' -e 's/ (netkey) on .*//')"
if ! printf '%s' "$ipsec_ver" | grep -q "Libreswan"; then
  exiterr "This script requires Libreswan already installed."
fi

if printf '%s' "$ipsec_ver" | grep -qF "$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

is_upgrade_to_323_or_newer=0
case "$SWAN_VER" in
  3.2[35])
    if ! printf '%s' "$ipsec_ver" | grep -qF -e "3.23" -e "3.25"; then
      is_upgrade_to_323_or_newer=1
    fi
    ;;
esac

is_downgrade_to_322_or_older=0
case "$SWAN_VER" in
  3.19|3.2[012])
    if printf '%s' "$ipsec_ver" | grep -qF -e "3.23" -e "3.25"; then
      is_downgrade_to_322_or_older=1
    fi
    ;;
esac

clear

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

It is intended for upgrading servers to a newer Libreswan version.

Current version:    $ipsec_ver_short
Version to install: Libreswan $SWAN_VER

EOF

case "$SWAN_VER" in
  3.2[35])
cat <<'EOF'
WARNING: Libreswan 3.23 and 3.25 have an issue with connecting multiple
    IPsec/XAuth VPN clients from behind the same NAT (e.g. home router).
    DO NOT upgrade to 3.23/3.25 if your use cases include the above.

EOF
    ;;
esac

cat <<'EOF'
NOTE: Libreswan versions 3.19 and newer require some configuration changes.
    This script will make the following updates to your /etc/ipsec.conf:

    1. Replace "auth=esp" with "phase2=esp"
    2. Replace "forceencaps=yes" with "encapsulation=yes"
    3. 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 || exit 1

# Install Wget
yum -y install wget || exiterr2

# Add the EPEL repository
epel_url="https://dl.fedoraproject.org/pub/epel/epel-release-latest-$(rpm -E '%{rhel}').noarch.rpm"
yum -y install epel-release || yum -y install "$epel_url" || 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 || exiterr2

REPO1='--enablerepo=*server-optional*'
REPO2='--enablerepo=*releases-optional*'
if grep -qs "release 6" /etc/redhat-release; then
  yum -y remove libevent-devel
  yum "$REPO1" "$REPO2" -y install libevent2-devel fipscheck-devel || exiterr2
else
  yum -y install systemd-devel || exiterr2
  yum "$REPO1" "$REPO2" -y install libevent-devel fipscheck-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" "$swan_url2"; }; then
  exit 1
fi
/bin/rm -rf "/opt/src/libreswan-$SWAN_VER"
tar xzf "$swan_file" && /bin/rm -f "$swan_file"
cd "libreswan-$SWAN_VER" || exit 1
[ "$SWAN_VER" = "3.22" ] && sed -i '/^#define LSWBUF_CANARY/s/-2$/((char) -2)/' include/lswlog.h
sed -i '/docker-targets\.mk/d' Makefile
cat > Makefile.inc.local <<'EOF'
WERROR_CFLAGS =
USE_DNSSEC = false
USE_GLIBC_KERN_FLIP_HEADERS = true
EOF
NPROCS="$(grep -c ^processor /proc/cpuinfo)"
[ -z "$NPROCS" ] && NPROCS=1
make "-j$((NPROCS+1))" -s base && make -s install-base

# Verify the install and clean up
cd /opt/src || exit 1
/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
IKE_NEW="  ike=3des-sha1,3des-sha2,aes-sha1,aes-sha1;modp1024,aes-sha2,aes-sha2;modp1024"
PHASE2_NEW="  phase2alg=3des-sha1,3des-sha2,aes-sha1,aes-sha2,aes256-sha2_512"
sed -i".old-$(date +%F-%T)" \
    -e "s/^[[:space:]]\+auth=esp\$/  phase2=esp/" \
    -e "s/^[[:space:]]\+forceencaps=yes\$/  encapsulation=yes/" \
    -e "s/^[[:space:]]\+ike=.\+\$/$IKE_NEW/" \
    -e "s/^[[:space:]]\+phase2alg=.\+\$/$PHASE2_NEW/" /etc/ipsec.conf

# Restart IPsec service
mkdir -p /run/pluto
service ipsec restart

cat <<EOF


===================================================

Libreswan $SWAN_VER has been successfully installed!

===================================================

EOF

if [ "$is_upgrade_to_323_or_newer" = "1" ]; then
cat <<'EOF'
IMPORTANT: Users upgrading to Libreswan 3.23 or newer must edit /etc/ipsec.conf
    and replace these two lines:

      modecfgdns1=DNS_SERVER_1
      modecfgdns2=DNS_SERVER_2

    with a single line like this:

      modecfgdns="DNS_SERVER_1, DNS_SERVER_2"

    Then run "service ipsec restart".

EOF
fi

if [ "$is_downgrade_to_322_or_older" = "1" ]; then
cat <<'EOF'
IMPORTANT: Users downgrading to Libreswan 3.22 or older must edit /etc/ipsec.conf
    and replace this line:

      modecfgdns="DNS_SERVER_1, DNS_SERVER_2"

    with two lines like this:

      modecfgdns1=DNS_SERVER_1
      modecfgdns2=DNS_SERVER_2

    Then run "service ipsec restart".

EOF
fi

}

## Defer setup until we have the complete script
vpnupgrade "$@"

exit 0