VerifactuMidAPI/internal/cert/validator.go

package cert

import (
	"encoding/base64"
	"time"

	"golang.org/x/crypto/pkcs12"
)

type ValidationResult struct {
	Valid    bool      `json:"valid"`
	CertInfo *CertInfo `json:"cert_info,omitempty"`
	Warnings []string  `json:"warnings,omitempty"`
	Error    string    `json:"error,omitempty"`
}

type CertInfo struct {
	Subject         string `json:"subject"`
	Issuer          string `json:"issuer"`
	NotBefore       string `json:"not_before"`
	NotAfter        string `json:"not_after"`
	Expired         bool   `json:"expired"`
	ExpiringSoon    bool   `json:"expiring_soon"`
	DaysUntilExpiry int    `json:"days_until_expiry"`
}

const WarningDaysThreshold = 30

func ValidateP12(base64Content, password string) *ValidationResult {
	result := &ValidationResult{Valid: true}

	der, err := base64.StdEncoding.DecodeString(base64Content)
	if err != nil {
		result.Valid = false
		result.Error = "invalid_base64"
		return result
	}

	_, cert, err := pkcs12.Decode(der, password)
	if err != nil {
		result.Valid = false
		result.Error = "invalid_password_or_format"
		return result
	}

	if cert == nil {
		result.Valid = false
		result.Error = "no_certificate_found"
		return result
	}

	now := time.Now()
	if now.Before(cert.NotBefore) {
		result.Valid = false
		result.Error = "certificate_not_yet_valid"
		return result
	}

	if now.After(cert.NotAfter) {
		result.Valid = false
		result.Error = "certificate_expired"
		result.CertInfo = &CertInfo{Expired: true}
		return result
	}

	daysUntilExpiry := int(cert.NotAfter.Sub(now).Hours() / 24)

	result.CertInfo = &CertInfo{
		Subject:         cert.Subject.String(),
		Issuer:          cert.Issuer.String(),
		NotBefore:       cert.NotBefore.Format("2006-01-02"),
		NotAfter:        cert.NotAfter.Format("2006-01-02"),
		DaysUntilExpiry: daysUntilExpiry,
	}

	if daysUntilExpiry <= WarningDaysThreshold {
		result.Warnings = append(result.Warnings, "certificate_expiring_soon")
		result.CertInfo.ExpiringSoon = true
	}

	return result
}