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package certificate
import (
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"errors"
"fmt"
"path/filepath"
"strings"
"sync"
"time"
)
// A Store maps certificate scopes to certificates.
// It generate certificates as needed and rotates expired certificates.
// The zero value for Store is an empty store ready to use.
//
// Certificate scopes must be registered with Register before certificate
// retrieval; otherwise Get will fail. This prevents the Store from
// creating unnecessary certificates.
//
// Store is safe for concurrent use by multiple goroutines.
type Store struct {
// CreateCertificate, if not nil, is called to create a new certificate
// to replace a missing or expired certificate. If CreateCertificate
// is nil, a certificate with a duration of 1 year will be created.
// The provided scope is suitable for use in a certificate's DNSNames.
CreateCertificate func(scope string) (tls.Certificate, error)
certs map[string]tls.Certificate
path string
mu sync.RWMutex
}
// Register registers the provided scope with the certificate store.
// The scope can either be a hostname or a wildcard pattern (e.g. "*.example.com").
// To accept all hostnames, use the special pattern "*".
func (s *Store) Register(scope string) {
s.mu.Lock()
defer s.mu.Unlock()
if s.certs == nil {
s.certs = make(map[string]tls.Certificate)
}
s.certs[scope] = tls.Certificate{}
}
// Add adds a certificate with the given scope to the certificate store.
func (s *Store) Add(scope string, cert tls.Certificate) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.certs == nil {
s.certs = make(map[string]tls.Certificate)
}
// Parse certificate if not already parsed
if cert.Leaf == nil {
parsed, err := x509.ParseCertificate(cert.Certificate[0])
if err != nil {
return err
}
cert.Leaf = parsed
}
if s.path != "" {
certPath := filepath.Join(s.path, scope+".crt")
keyPath := filepath.Join(s.path, scope+".key")
if err := Write(cert, certPath, keyPath); err != nil {
return err
}
}
s.certs[scope] = cert
return nil
}
// Get retrieves a certificate for the given hostname.
// It checks to see if the hostname or a matching pattern has been registered.
// New certificates are generated on demand and expired certificates are
// replaced with new ones.
func (s *Store) Get(hostname string) (*tls.Certificate, error) {
s.mu.RLock()
defer s.mu.RUnlock()
cert, ok := s.certs[hostname]
if !ok {
// Try "*"
_, ok = s.certs["*"]
}
if !ok {
// Try wildcard
wildcard := strings.SplitN(hostname, ".", 2)
if len(wildcard) == 2 {
hostname = "*." + wildcard[1]
cert, ok = s.certs[hostname]
}
}
if !ok {
return nil, errors.New("unrecognized scope")
}
// If the certificate is empty or expired, generate a new one.
if cert.Leaf == nil || cert.Leaf.NotAfter.Before(time.Now()) {
var err error
cert, err = s.createCertificate(hostname)
if err != nil {
return nil, err
}
if err := s.Add(hostname, cert); err != nil {
return nil, fmt.Errorf("failed to add certificate for %s: %w", hostname, err)
}
}
return &cert, nil
}
func (s *Store) createCertificate(scope string) (tls.Certificate, error) {
if s.CreateCertificate != nil {
return s.CreateCertificate(scope)
}
return Create(CreateOptions{
DNSNames: []string{scope},
Subject: pkix.Name{
CommonName: scope,
},
Duration: 365 * 24 * time.Hour,
})
}
// Load loads certificates from the provided path.
// New certificates will be written to this path.
// Certificates with scopes that have not been registered will be ignored.
//
// The path should lead to a directory containing certificates
// and private keys named "scope.crt" and "scope.key" respectively,
// where "scope" is the scope of the certificate.
func (s *Store) Load(path string) error {
matches, err := filepath.Glob(filepath.Join(path, "*.crt"))
if err != nil {
return err
}
for _, crtPath := range matches {
scope := strings.TrimSuffix(filepath.Base(crtPath), ".crt")
if _, ok := s.certs[scope]; !ok {
continue
}
keyPath := strings.TrimSuffix(crtPath, ".crt") + ".key"
cert, err := tls.LoadX509KeyPair(crtPath, keyPath)
if err != nil {
continue
}
s.Add(scope, cert)
}
s.SetPath(path)
return nil
}
// Entries returns a map of scopes to certificates.
func (s *Store) Entries() map[string]tls.Certificate {
s.mu.RLock()
defer s.mu.RUnlock()
certs := make(map[string]tls.Certificate)
for key := range s.certs {
certs[key] = s.certs[key]
}
return certs
}
// SetPath sets the path that new certificates will be written to.
func (s *Store) SetPath(path string) {
s.mu.Lock()
defer s.mu.Unlock()
s.path = path
}
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