Add new option

- Add an option for specifying a Libreswan version to install,
  using variable VPN_SWAN_VER. Currently supported values are
  4.15 and 5.0. This could be useful for users who want to
  install the older Libreswan version 4.

vpnsetup.sh

@@ -280,7 +280,7 @@ run_setup() {
       VPN_DNS_NAME="$VPN_DNS_NAME" VPN_CLIENT_NAME="$VPN_CLIENT_NAME" \
       VPN_PROTECT_CONFIG="$VPN_PROTECT_CONFIG" \
       VPN_CLIENT_VALIDITY="$VPN_CLIENT_VALIDITY" \
-      VPN_SKIP_IKEV2="$VPN_SKIP_IKEV2" \
+      VPN_SKIP_IKEV2="$VPN_SKIP_IKEV2" VPN_SWAN_VER="$VPN_SWAN_VER" \
       /bin/bash "$tmpdir/vpn.sh" || status=1
     else
       status=1

vpnsetup_alpine.sh

@@ -248,6 +248,18 @@ get_swan_ver() {
   if printf '%s' "$swan_ver_latest" | grep -Eq '^([3-9]|[1-9][0-9]{1,2})(\.([0-9]|[1-9][0-9]{1,2})){1,2}$'; then
     SWAN_VER="$swan_ver_latest"
   fi
+  if [ -n "$VPN_SWAN_VER" ]; then
+    if ! printf '%s\n%s' "4.15" "$VPN_SWAN_VER" | sort -C -V \
+      || ! printf '%s\n%s' "$VPN_SWAN_VER" "$SWAN_VER" | sort -C -V; then
+cat 1>&2 <<EOF
+Error: Libreswan version '$VPN_SWAN_VER' is not supported.
+       This script can install Libreswan 4.15+ or $SWAN_VER.
+EOF
+      exit 1
+    else
+      SWAN_VER="$VPN_SWAN_VER"
+    fi
+  fi
 }
 
 check_libreswan() {

vpnsetup_amzn.sh

@@ -266,6 +266,18 @@ get_swan_ver() {
   if printf '%s' "$swan_ver_latest" | grep -Eq '^([3-9]|[1-9][0-9]{1,2})(\.([0-9]|[1-9][0-9]{1,2})){1,2}$'; then
     SWAN_VER="$swan_ver_latest"
   fi
+  if [ -n "$VPN_SWAN_VER" ]; then
+    if ! printf '%s\n%s' "4.15" "$VPN_SWAN_VER" | sort -C -V \
+      || ! printf '%s\n%s' "$VPN_SWAN_VER" "$SWAN_VER" | sort -C -V; then
+cat 1>&2 <<EOF
+Error: Libreswan version '$VPN_SWAN_VER' is not supported.
+       This script can install Libreswan 4.15+ or $SWAN_VER.
+EOF
+      exit 1
+    else
+      SWAN_VER="$VPN_SWAN_VER"
+    fi
+  fi
 }
 
 check_libreswan() {

vpnsetup_centos.sh

@@ -368,6 +368,18 @@ get_swan_ver() {
   if printf '%s' "$swan_ver_latest" | grep -Eq '^([3-9]|[1-9][0-9]{1,2})(\.([0-9]|[1-9][0-9]{1,2})){1,2}$'; then
     SWAN_VER="$swan_ver_latest"
   fi
+  if [ -n "$VPN_SWAN_VER" ]; then
+    if ! printf '%s\n%s' "4.15" "$VPN_SWAN_VER" | sort -C -V \
+      || ! printf '%s\n%s' "$VPN_SWAN_VER" "$SWAN_VER" | sort -C -V; then
+cat 1>&2 <<EOF
+Error: Libreswan version '$VPN_SWAN_VER' is not supported.
+       This script can install Libreswan 4.15+ or $SWAN_VER.
+EOF
+      exit 1
+    else
+      SWAN_VER="$VPN_SWAN_VER"
+    fi
+  fi
 }
 
 check_libreswan() {

vpnsetup_ubuntu.sh

@@ -321,6 +321,18 @@ get_swan_ver() {
   if printf '%s' "$swan_ver_latest" | grep -Eq '^([3-9]|[1-9][0-9]{1,2})(\.([0-9]|[1-9][0-9]{1,2})){1,2}$'; then
     SWAN_VER="$swan_ver_latest"
   fi
+  if [ -n "$VPN_SWAN_VER" ]; then
+    if ! printf '%s\n%s' "4.15" "$VPN_SWAN_VER" | sort -C -V \
+      || ! printf '%s\n%s' "$VPN_SWAN_VER" "$SWAN_VER" | sort -C -V; then
+cat 1>&2 <<EOF
+Error: Libreswan version '$VPN_SWAN_VER' is not supported.
+       This script can install Libreswan 4.15+ or $SWAN_VER.
+EOF
+      exit 1
+    else
+      SWAN_VER="$VPN_SWAN_VER"
+    fi
+  fi
 }
 
 check_libreswan() {