add suppressIPDiff and canonicalizeIP helpers -- use in resourceVultrFirewallRule

[wiggels]

…FirewallRule (#714)

Description

Fix IPv6 subnet normalization drift on firewall rules. The Vultr API normalizes IPv6 addresses on return by stripping leading zeros per RFC 5952 (e.g., 05ff becomes 5ff). This causes Terraform to detect a perpetual diff and attempt to recreate the rule on every plan.

Adds a DiffSuppressFunc that compares parsed IP bytes instead of strings, and a StateFunc that canonicalizes the subnet on write so state always matches the API response. Handles both v4 and v6 transparently.

Related Issues

Fixes #714

Checklist:

• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you linted your code locally prior to submission?
• Have you successfully ran tests with your changes locally?

[github-actions]

Failed to generate code suggestions for PR

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 714 - Partially compliant Compliant requirements: Added DiffSuppressFunc (suppressIPDiff) that compares parsed IP bytes instead of strings Added StateFunc (canonicalizeIP) that canonicalizes subnet on write to match API response Both IPv4 and IPv6 are handled transparently Tests verify leading zero stripping, compression, mixed case hex, and different address detection Non-compliant requirements: None identified Requires further human verification: None - the fix is fully contained in the PR and testable via unit tests

⏱️ Estimated effort to review: 1 🔵⚪⚪⚪⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ Recommended focus areas for review

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Add safe type assertion to prevent panic The type assertion val.(string) will panic if val is not a string (e.g., if Terraform passes nil or a different type). Use a type assertion with comma-ok idiom to safely handle unexpected types. vultr/utility.go [69-76] func canonicalizeIP(val interface{}) string { - raw := val.(string) + raw, ok := val.(string) + if !ok { + return "" + } ip := net.ParseIP(raw) if ip == nil { return raw } return ip.String() } Suggestion importance[1-10]: 5 __ Why: The suggestion correctly identifies a potential panic scenario from unsafe type assertion. While this is a defensive improvement, Terraform's StateFunc typically receives the correct type based on the schema definition, so the risk is low. The fix is valid and improves robustness.	Low

[optik-aper]

Good to merge