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package certificate
import (
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"errors"
"fmt"
"os"
"path/filepath"
"strings"
"sync"
"time"
)
// A Store represents a TLS certificate store.
// The zero value for Store is an empty store ready to use.
//
// Store can be used to store server certificates.
// Servers should provide a hostname or wildcard pattern as a certificate scope.
// Servers will most likely use the methods Register, Load and Get.
//
// Store can also be used to store client certificates.
// Clients should provide a hostname as a certificate scope.
// Clients will most likely use the methods Add, Load, and Lookup.
//
// Store is safe for concurrent use by multiple goroutines.
type Store struct {
// CreateCertificate, if not nil, is called by Get to create a new
// certificate to replace a missing or expired certificate.
// The provided scope is suitable for use in a certificate's DNSNames.
CreateCertificate func(scope string) (tls.Certificate, error)
scopes map[string]struct{}
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 "*".
//
// Calls to Get will only succeed for registered scopes.
// Other methods are not affected.
func (s *Store) Register(scope string) {
s.mu.Lock()
defer s.mu.Unlock()
if s.scopes == nil {
s.scopes = make(map[string]struct{})
}
s.scopes[scope] = struct{}{}
}
// Add registers the certificate for the given scope.
// If a certificate already exists for scope, Add will overwrite it.
func (s *Store) Add(scope string, cert tls.Certificate) error {
// 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 err := s.write(scope, cert); err != nil {
return err
}
s.mu.Lock()
defer s.mu.Unlock()
if s.certs == nil {
s.certs = make(map[string]tls.Certificate)
}
s.certs[scope] = cert
return nil
}
func (s *Store) write(scope string, cert tls.Certificate) error {
s.mu.RLock()
defer s.mu.RUnlock()
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
}
}
return nil
}
// Get retrieves a certificate for the given hostname.
// If no matching scope has been registered, Get returns an error.
// Get generates new certificates as needed and rotates expired certificates.
// It calls CreateCertificate to create a new certificate if it is not nil,
// otherwise it creates certificates with a duration of 100 years.
//
// Get is suitable for use in a gemini.Server's GetCertificate field.
func (s *Store) Get(hostname string) (*tls.Certificate, error) {
s.mu.RLock()
_, ok := s.scopes[hostname]
if !ok {
// Try wildcard
wildcard := strings.SplitN(hostname, ".", 2)
if len(wildcard) == 2 {
hostname = "*." + wildcard[1]
_, ok = s.scopes[hostname]
}
}
if !ok {
// Try "*"
_, ok = s.scopes["*"]
}
if !ok {
s.mu.RUnlock()
return nil, errors.New("unrecognized scope")
}
cert := s.certs[hostname]
s.mu.RUnlock()
// 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
}
// Lookup returns the certificate for the provided scope.
func (s *Store) Lookup(scope string) (tls.Certificate, bool) {
s.mu.RLock()
defer s.mu.RUnlock()
cert, ok := s.certs[scope]
return cert, ok
}
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: 100 * 365 * 24 * time.Hour,
})
}
// Load loads certificates from the provided path.
// New certificates will be written to this path.
// 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 {
if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil {
return err
}
path = filepath.Clean(path)
matches, err := filepath.Glob(filepath.Join(path, "*.crt"))
if err != nil {
return err
}
for _, crtPath := range matches {
keyPath := strings.TrimSuffix(crtPath, ".crt") + ".key"
cert, err := tls.LoadX509KeyPair(crtPath, keyPath)
if err != nil {
continue
}
scope := strings.TrimPrefix(crtPath, path)
scope = strings.TrimPrefix(scope, "/")
scope = strings.TrimSuffix(scope, ".crt")
s.Add(scope, cert)
}
s.mu.Lock()
defer s.mu.Unlock()
s.path = 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 = filepath.Clean(path)
}
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