Improve Libreswan install

- Skip downloading and installing Libreswan if the same version
  is already installed.

vpnsetup_amzn.sh

@@ -184,9 +184,16 @@ get_ikev2_script() {
   [ -s ikev2.sh ] && chmod +x ikev2.sh && ln -s /opt/src/ikev2.sh /usr/bin 2>/dev/null
 }
 
-get_libreswan() {
+check_libreswan() {
-  bigecho "Downloading Libreswan..."
   SWAN_VER=4.5
+  ipsec_ver=$(/usr/local/sbin/ipsec --version 2>/dev/null)
+  swan_ver_old=$(printf '%s' "$ipsec_ver" | sed -e 's/.*Libreswan U\?//' -e 's/\( (\|\/K\).*//')
+  [ "$swan_ver_old" = "$SWAN_VER" ]
+}
+
+get_libreswan() {
+  if ! check_libreswan; then
+    bigecho "Downloading 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/$swan_file"
@@ -196,9 +203,13 @@ get_libreswan() {
     ) || exit 1
     /bin/rm -rf "/opt/src/libreswan-$SWAN_VER"
     tar xzf "$swan_file" && /bin/rm -f "$swan_file"
+  else
+    bigecho "Libreswan $SWAN_VER is already installed, skipping..."
+  fi
 }
 
 install_libreswan() {
+  if ! check_libreswan; then
     bigecho "Compiling and installing Libreswan, please wait..."
     cd "libreswan-$SWAN_VER" || exit 1
 cat > Makefile.inc.local <<'EOF'
@@ -223,6 +234,7 @@ EOF
     if ! /usr/local/sbin/ipsec --version 2>/dev/null | grep -qF "$SWAN_VER"; then
       exiterr "Libreswan $SWAN_VER failed to build."
     fi
+  fi
 }
 
 create_vpn_config() {

vpnsetup_centos.sh

@@ -238,9 +238,16 @@ get_ikev2_script() {
   [ -s ikev2.sh ] && chmod +x ikev2.sh && ln -s /opt/src/ikev2.sh /usr/bin 2>/dev/null
 }
 
-get_libreswan() {
+check_libreswan() {
-  bigecho "Downloading Libreswan..."
   SWAN_VER=4.5
+  ipsec_ver=$(/usr/local/sbin/ipsec --version 2>/dev/null)
+  swan_ver_old=$(printf '%s' "$ipsec_ver" | sed -e 's/.*Libreswan U\?//' -e 's/\( (\|\/K\).*//')
+  [ "$swan_ver_old" = "$SWAN_VER" ]
+}
+
+get_libreswan() {
+  if ! check_libreswan; then
+    bigecho "Downloading 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/$swan_file"
@@ -250,9 +257,13 @@ get_libreswan() {
     ) || exit 1
     /bin/rm -rf "/opt/src/libreswan-$SWAN_VER"
     tar xzf "$swan_file" && /bin/rm -f "$swan_file"
+  else
+    bigecho "Libreswan $SWAN_VER is already installed, skipping..."
+  fi
 }
 
 install_libreswan() {
+  if ! check_libreswan; then
     bigecho "Compiling and installing Libreswan, please wait..."
     cd "libreswan-$SWAN_VER" || exit 1
 cat > Makefile.inc.local <<'EOF'
@@ -277,6 +288,7 @@ EOF
     if ! /usr/local/sbin/ipsec --version 2>/dev/null | grep -qF "$SWAN_VER"; then
       exiterr "Libreswan $SWAN_VER failed to build."
     fi
+  fi
 }
 
 create_vpn_config() {

vpnsetup_ubuntu.sh

@@ -226,9 +226,16 @@ get_ikev2_script() {
   [ -s ikev2.sh ] && chmod +x ikev2.sh && ln -s /opt/src/ikev2.sh /usr/bin 2>/dev/null
 }
 
-get_libreswan() {
+check_libreswan() {
-  bigecho "Downloading Libreswan..."
   SWAN_VER=4.5
+  ipsec_ver=$(/usr/local/sbin/ipsec --version 2>/dev/null)
+  swan_ver_old=$(printf '%s' "$ipsec_ver" | sed -e 's/.*Libreswan U\?//' -e 's/\( (\|\/K\).*//')
+  [ "$swan_ver_old" = "$SWAN_VER" ]
+}
+
+get_libreswan() {
+  if ! check_libreswan; then
+    bigecho "Downloading 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/$swan_file"
@@ -238,9 +245,13 @@ get_libreswan() {
     ) || exit 1
     /bin/rm -rf "/opt/src/libreswan-$SWAN_VER"
     tar xzf "$swan_file" && /bin/rm -f "$swan_file"
+  else
+    bigecho "Libreswan $SWAN_VER is already installed, skipping..."
+  fi
 }
 
 install_libreswan() {
+  if ! check_libreswan; then
     bigecho "Compiling and installing Libreswan, please wait..."
     cd "libreswan-$SWAN_VER" || exit 1
 cat > Makefile.inc.local <<'EOF'
@@ -273,6 +284,7 @@ EOF
     if ! /usr/local/sbin/ipsec --version 2>/dev/null | grep -qF "$SWAN_VER"; then
       exiterr "Libreswan $SWAN_VER failed to build."
     fi
+  fi
 }
 
 create_vpn_config() {