PARENT: Implement validation for DNS request inputs

[jasonBirchall]

User Need

As an engineer,
I want to validate user input before it's used,
so that I can catch any issues at the source and reduce time spent on back-and-forth with the user.

Value

Validating the user input ensures that the data provided is correct from the start. This reduces the time spent contacting users for corrections, minimises errors in DNS changes, and improves the overall efficiency of the process.

Child Tickets

• [ ] https://github.com/ministryofjustice/operations-engineering/issues/4863
• [ ] https://github.com/ministryofjustice/operations-engineering/issues/4864
• [ ] https://github.com/ministryofjustice/operations-engineering/issues/4865
• [ ] https://github.com/ministryofjustice/operations-engineering/issues/4866

Functional Requirements (What):

• [ ] Implement validator functions for each user input field as outlined in the previous ticket.
• [ ] Validators should check inputs such as domain names, IP addresses, and other DNS-related data according to the standards defined in the document.
• [ ] Validation should include checks using regular expressions and other programmatically verifiable variables.

Non-Functional Requirements (How):

• [ ] Validator functions should be added to the existing validators script.
• [ ] Most validation should use regex patterns, where appropriate, for fields like domain names and IP addresses.
• [ ] Use programmatic DNS validation for fields where regex isn't appropriate.
• [ ] Ensure that validation provides clear error messages when input is incorrect.

Acceptance Criteria:

• [ ] Validation functions for all required user inputs exist and pass verification.
• [ ] Unit tests are created for each validation function and run successfully.
• [ ] The validation follows the guidelines outlined in the shared document.

Notes:

The document linked above outlines all the form fields and corresponding validation requirements. Validators should be applied consistently to ensure that all user inputs conform to the required DNS standards.

[abachleda-baca]

I have implemented validation for some of the fields using Flask's message flashing functionality and the gov guidance on how to display errors. However, after reviewing the attached document I was unsure about which validation rules should be applied. It might be worthwhile to review this and agree on the input data requirements for each field.

• MoJ Service Owner, Service Area Name: It is advised that these fields should have fixed list of values, but it has not been provided.
• DNS Record: Autocomplete is required instead of validation.
• TTL: The minimum and maximum values have not been provided.
• DNS Record value per type of request: Is it sufficient to use a generalized regular expression for a DNS domain name, or should we apply more specific validation based on each type of DNS record?

[levgorbunov1]

This ticket is massive, spinning off children