Incorrect Domain Splitting for DuckDNS Subdomains (e.g., xray-il.duckdns.org)

[mina-atef-00]

When using a full DuckDNS subdomain (such as xray-il.duckdns.org) with the x‑UI‑PRO installation script, the domain splitting logic incorrectly interprets the input. Instead of treating the entire string as the domain, the script splits it into a subdomain and main domain by assuming a format of sub.domain.tld. This results in:

• SubDomain: xray-il
• MainDomain: duckdns.org

Consequently, the SSL certificate is generated (via Certbot) with the cert-name duckdns.org and the Nginx configuration sets server_name to duckdns.org *.duckdns.org, which does not reflect the intended usage since I only registered xray-il.duckdns.org.

Steps to Reproduce:

1. Register a subdomain with DuckDNS (e.g., xray-il.duckdns.org).
2. Run the installation script and, when prompted, enter xray-il.duckdns.org as the available subdomain.
3. Observe that the script splits the domain into xray-il and duckdns.org—leading Certbot to create certificates under /etc/letsencrypt/live/duckdns.org/ and Nginx’s server block is configured for duckdns.org *.duckdns.org.

Expected Behavior:
For a registered full subdomain like xray-il.duckdns.org, the script should treat the entire input as the main domain. This would ensure that:

• The SSL certificate is issued for xray-il.duckdns.org (with cert-name set to the full domain).
• The Nginx configuration uses server_name xray-il.duckdns.org; (or similarly appropriate directives).

Actual Behavior:
The script’s current logic splits the input into two parts, which:

• Causes the certificate to be issued under duckdns.org (instead of xray-il.duckdns.org).
• Configures Nginx for duckdns.org *.duckdns.org, which may lead to SSL validation issues and misconfiguration when accessing the panel.

Possible Solutions:

1. Modify the Domain Parsing Logic:
   Adjust the domain extraction section in the script so that if the provided domain ends with duckdns.org (or any known third-party provider domain), the entire input is used as the main domain. For example, replacing the domain-splitting block with:

   while [[ -z $(echo "$domain" | tr -d '[:space:]') ]]; do
       read -rp $'\e[1;32;40m Enter available subdomain (sub.domain.tld): \e[0m' domain
   done
   
   domain=$(echo "$domain" | tr -d '[:space:]')
   # If the domain ends with duckdns.org, use the whole string as MainDomain.
   if [[ "$domain" =~ duckdns\.org$ ]]; then
       MainDomain="${domain}"
   else
       SubDomain=$(echo "$domain" | sed 's/^[^ ]* \|\..*//g')
       MainDomain=$(echo "$domain" | sed 's/.*\.\([^.]*\..*\)$/\1/')
       if [[ "${SubDomain}.${MainDomain}" != "${domain}" ]]; then
           MainDomain="${domain}"
       fi
   fi
   
   

2. Provide a Flag to Bypass Domain Splitting: Offer an installation argument that allows users to bypass the automatic domain splitting for cases where they register a full subdomain (e.g., DuckDNS).

Environment:

x‑UI‑PRO version: v11.8.2 (or latest, as applicable)
Domain Provider: DuckDNS (using a full subdomain like xray-il.duckdns.org)

Additional Context: Users who utilize third-party subdomain providers (such as DuckDNS) should be able to have the script generate SSL certificates and server configurations for the exact domain they registered. The current logic assumes a standard two-level domain structure (e.g., example.com with a subdomain like panel.example.com), which does not align with full subdomains provided by services like DuckDNS.