✅ Validation & Normalization

This module validates CPE objects and component values against the CPE 2.3 specification, normalizes values into a canonical form, and converts between URI and file-system-safe string forms. The logical-value constants ValueANY (*) and ValueNA (-) used throughout validation are declared in wfn.go (see the WFN module); validation.go itself declares no exported constants — its character sets and special-value maps are unexported.

✔️ ValidateComponent

func ValidateComponent(value string, componentName string) error

Validates a single CPE component value against the CPE 2.3 character rules. The empty string and the logical values * (ANY) and - (NA) are accepted. Any value containing an illegal character (from the internal illegalChars set) or an ASCII control character (outside the range 32–126) is rejected.

Parameter	Type	Description
value	string	The component value to validate
componentName	string	Component name, used in the error message

Return	Type	Description
#1	error	nil if valid, otherwise an InvalidAttributeError

fmt.Println(cpeskills.ValidateComponent("windows", "ProductName")) // <nil>
fmt.Println(cpeskills.ValidateComponent("*", "Version"))           // <nil>
fmt.Println(cpeskills.ValidateComponent("product#1", "ProductName")) // error

✔️ ValidateCPE

func ValidateCPE(cpe *CPE) error

Validates a CPE object as a whole: ensures Part is non-empty and one of a, h, o, or *; ensures Vendor and ProductName are non-empty; and runs ValidateComponent against every attribute. A nil CPE returns an InvalidFormatError.

Parameter	Type	Description
cpe	*CPE	The CPE object to validate

Return	Type	Description
#1	error	nil if valid, otherwise a descriptive error

cpe := &cpeskills.CPE{
    Part:        *cpeskills.PartApplication,
    Vendor:      cpeskills.Vendor("microsoft"),
    ProductName: cpeskills.Product("windows"),
    Version:     cpeskills.Version("10"),
}
fmt.Println(cpeskills.ValidateCPE(cpe)) // <nil>

🧹 NormalizeComponent

func NormalizeComponent(value string) string

Normalizes a component value to the CPE 2.3 canonical form: lowercases the value, replaces spaces with underscores, and collapses runs of consecutive underscores into one. The logical values (*, -) and the empty string are returned unchanged.

Parameter	Type	Description
value	string	The raw component value

Return	Type	Description
#1	string	The normalized value

fmt.Println(cpeskills.NormalizeComponent("Windows 10"))        // windows_10
fmt.Println(cpeskills.NormalizeComponent("Microsoft  Office")) // microsoft_office
fmt.Println(cpeskills.NormalizeComponent("*"))                 // *

🧹 NormalizeCPE

func NormalizeCPE(cpe *CPE) *CPE

Returns a new CPE whose attribute values have been normalized via NormalizeComponent. The original object is not modified. If at least one of Vendor, ProductName, or Version is set, the Cpe23 field is regenerated from the normalized values via FormatCpe23. The Cve and Url extension fields are preserved. A nil input returns nil.

Parameter	Type	Description
cpe	*CPE	The CPE to normalize

Return	Type	Description
#1	*CPE	A new, normalized CPE (or nil if input is nil)

original := &cpeskills.CPE{
    Part:        *cpeskills.PartApplication,
    Vendor:      cpeskills.Vendor("Microsoft"),
    ProductName: cpeskills.Product("Windows 10"),
    Version:     cpeskills.Version("1.0"),
}
normalized := cpeskills.NormalizeCPE(original)
fmt.Println(string(normalized.Vendor))      // microsoft
fmt.Println(string(normalized.ProductName)) // windows_10

🔁 FSStringToURI

func FSStringToURI(fs string) string

Converts a file-system-safe CPE string back into a standard CPE 2.3 URI string. The conversion reverses the underscore-based separators (___ → :, _ → :) and restores the special cases handled by URIToFSString.

Note: this function contains hard-coded handling for specific test cases and may not be fully reversible for arbitrary inputs.

Parameter	Type	Description
fs	string	A file-system-safe CPE string

Return	Type	Description
#1	string	The standard CPE 2.3 URI string

fmt.Println(cpeskills.FSStringToURI("cpe___2.3_a_vendor_product_1.0_-_-_-_-_-_-_-"))
// cpe:2.3:a:vendor:product:1.0:-:-:-:-:-:-:-

🔁 URIToFSString

func URIToFSString(uri string) string

Converts a standard CPE 2.3 URI string into a file-system-safe form, where : separators are replaced with _ (the first cpe:2.3 separator becomes cpe___2.3). Suitable for use as a file or path name.

Note: this function contains hard-coded handling for specific test cases (windows_server, example.com) and may not be fully reversible for arbitrary inputs.

Parameter	Type	Description
uri	string	A standard CPE 2.3 URI string

Return	Type	Description
#1	string	A file-system-safe CPE string

fmt.Println(cpeskills.URIToFSString("cpe:2.3:a:vendor:product:1.0:-:-:-:-:-:-:-"))
// cpe___2.3_a_vendor_product_1.0_-_-_-_-_-_-_-

📐 Validation & Normalization Flow Diagram