Add string validation to OpenAPI code templates.

[davidjwbbc]

Description

The current development branch for the rt-5gms-application-function contains openapi-generator templates that include some extra validation for number ranges.

One thing they do not currently validate are the values for string types which can have:

• a regex pattern match associated with them (ECMA 262 regex).
• a format type.
  • date, date-time, password, byte (base64 encoded) or binary (file reference) are the specified OpenAPI types.
• a minLength to define the minimum number of characters.
• a maxLength to define the maximum number of characters.

Design

The storage of string should be a char* unless the string has a format of byte or binary, in which case the storage shall be a void* for the data and a size_t representing the length. When byte is used as the format the string will be base64 decoded into the void* data block and the decoded length stored in the size_t.

The validation when checking a string type variable shall:

• check the string length (strlen()) or data block size_t value against minLength and/or maxLength, if available, and generate a parse error is the range check fails.
• if pattern is defined:
  • At the top level of the file a static regex pointer variable will be defined, using the structure and property name, which is initially set to NULL.
  • When parsing:
  • If the top level regex pointer is NULL then the regex is compiled and an exit tidy-up routine registered.
  • Use the compiled regex to match the string value and generate a parse error if it fails.
• If format is defined:
  • When date, check the string matches regex "^\d{4}-\d{2}-\d{2}$".
  • When date-time, check the string matches regex "^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:.\d+)?(?:Z|[-+]\d{2}:\d{2})$".
  • When password do nothing.
  • When byte then check that string is a valid base64 string (only correct base 64 symbols and correct number of = signs at the end for preceding number of base64 symbols).
  • When binary do nothing.
  • When any other value log a warning about not understanding the format and ignore format validation.

A tidy up function should also be included which will free any compiled regex structures that will be automatically registered as an atexit function.

[rjb1000]

When any other value log a warning about not understanding the format and ignore format validation.

How about a reassuring warning such as:

• Warning: unable to validate unknown string format "blah". Storing and continuing anyway.

[davidjwbbc]

Added in PR #164