diff --git a/scripts/_common.sh b/scripts/_common.sh
new file mode 100644
index 0000000..dee0ea0
--- /dev/null
+++ b/scripts/_common.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+
+#=================================================
+# COMMON VARIABLES
+#=================================================
+
+#=================================================
+# PERSONAL HELPERS
+#=================================================
+
+URL_REGEX_VALID='(https?|ftp|file)://[-A-Za-z0-9\+&@#/%?=~_|!:,.;]*[-A-Za-z0-9\+&@#/%=~_|]'
+URL_REGEX_SECURE='^(http://(127\.[0-9]+\.[0-9]+\.[0-9]+|localhost)|https://.*)(:[0-9]+)?(/.*)?$'
+
+_validate_redirect_uri() {
+    if [[ ! $target =~ $URL_REGEX_VALID ]]; then
+        ynh_die "Invalid destination: $target" 1
+    fi
+
+    # Avoid uncrypted remote destination with reverse proxy mode
+    # Indeed the SSO send the password in all requests in HTTP headers
+    if [[ "$redirect_type" = "proxy" ]] && [[ ! $target =~ $URL_REGEX_SECURE ]]; then
+        ynh_die "For secure reason, you can't use an unencrypted http remote destination couple with ssowat for your reverse proxy: $target" 1
+    fi
+}
+
+#=================================================
+# EXPERIMENTAL HELPERS
+#=================================================
+
+#=================================================
+# FUTURE OFFICIAL HELPERS
+#=================================================
diff --git a/scripts/install b/scripts/install
index 979fcfd..351e62d 100644
--- a/scripts/install
+++ b/scripts/install
@@ -6,20 +6,17 @@
 # IMPORT GENERIC HELPERS
 #=================================================
 
+source _common.sh
 source /usr/share/yunohost/helpers
 
-# Avoid uncrypted remote destination with reverse proxy mode
-# Indeed the SSO send the password in all requests in HTTP headers
-url_regex='^(http://(127\.[0-9]+\.[0-9]+\.[0-9]+|localhost)|https://.*)(:[0-9]+)?(/.*)?$'
-[[ "$redirect_type" = "reverseproxy" ]] && [[ ! "$target" =~ $url_regex ]] && ynh_die \
-"For secure reason, you can't use an unencrypted http remote destination coupled with ssowat for your reverse proxy: $target" 1
+_validate_redirect_uri
 
 #=================================================
 # CONFIGURE NGINX
 #=================================================
 ynh_script_progression --message="Configuring NGINX web server..." --weight=1
 
-mv ../conf/{nginx-$redirect_type.conf,nginx.conf}
+mv ../conf/{"nginx-$redirect_type.conf",nginx.conf}
 ynh_add_nginx_config
 
 #=================================================
diff --git a/scripts/upgrade b/scripts/upgrade
index 3605880..639b139 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -1,5 +1,6 @@
 #!/bin/bash
 
+source _common.sh
 source /usr/share/yunohost/helpers
 
 #=================================================