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package tlsutil
import (
"crypto/tls"
"crypto/x509"
"fmt"
"github.com/pkg/errors"
)
// ServerRenewFunc defines the type of the functions used to get a new tls
// certificate.
type ServerRenewFunc func(hello *tls.ClientHelloInfo) (*tls.Certificate, *tls.Config, error)
// ServerCredentials is a type that manages the credentials of a server.
type ServerCredentials struct {
RenewFunc ServerRenewFunc
cache *credentialsCache
}
// NewServerCredentials returns a new ServerCredentials that will get
// certificates from the given function.
func NewServerCredentials(fn ServerRenewFunc) (*ServerCredentials, error) {
return &ServerCredentials{
RenewFunc: fn,
cache: newCredentialsCache(),
}, nil
}
// NewServerCredentialsFromFile returns a ServerCredentials that renews the
// certificate from a file on disk.
func NewServerCredentialsFromFile(certFile, keyFile string) (*ServerCredentials, error) {
if _, err := tls.LoadX509KeyPair(certFile, keyFile); err != nil {
return nil, errors.Wrap(err, "error loading certificate")
}
return NewServerCredentials(func(*tls.ClientHelloInfo) (*tls.Certificate, *tls.Config, error) {
cert, err := tls.LoadX509KeyPair(certFile, keyFile)
if err != nil {
return nil, nil, errors.Wrap(err, "error loading certificate")
}
if cert.Leaf == nil {
cert.Leaf, err = x509.ParseCertificate(cert.Certificate[0])
if err != nil {
return nil, nil, errors.Wrap(err, "error parsing certificate")
}
}
return &cert, &tls.Config{
MinVersion: tls.VersionTLS12,
}, nil
})
}
// TLSConfig returns a *tls.Config with GetCertificate and GetConfigForClient
// set.
func (c *ServerCredentials) TLSConfig() *tls.Config {
return &tls.Config{
MinVersion: tls.VersionTLS12,
GetCertificate: c.GetCertificate,
GetConfigForClient: c.GetConfigForClient,
}
}
// GetCertificate returns the certificate for the SNI in the hello message.
func (c *ServerCredentials) GetCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
if hello.ServerName == "" {
return nil, fmt.Errorf("server name indication cannot be empty")
}
sni, err := SanitizeName(hello.ServerName)
if err != nil {
return nil, err
}
// Attempt to load a certificate.
if v, ok := c.cache.Load(sni); ok {
return v.renewer.GetCertificate(hello)
}
renewer, err := c.getCertificate(sni, hello)
if err != nil {
return nil, err
}
return renewer.GetCertificate(hello)
}
// GetConfigForClient returns the tls.Config used per request.
func (c *ServerCredentials) GetConfigForClient(hello *tls.ClientHelloInfo) (*tls.Config, error) {
if hello.ServerName == "" {
return nil, fmt.Errorf("server name indication cannot be empty")
}
sni, err := SanitizeName(hello.ServerName)
if err != nil {
return nil, err
}
if v, ok := c.cache.Load(sni); ok {
return v.renewer.GetConfigForClient(hello)
}
renewer, err := c.getCertificate(sni, hello)
if err != nil {
return nil, err
}
return renewer.GetConfigForClient(hello)
}
func (c *ServerCredentials) getCertificate(sni string, hello *tls.ClientHelloInfo) (*Renewer, error) {
cert, tlsConfig, err := c.RenewFunc(hello)
if err != nil {
return nil, err
}
renewer, err := NewRenewer(cert, tlsConfig, func() (*tls.Certificate, *tls.Config, error) {
return c.RenewFunc(hello)
})
if err != nil {
return nil, err
}
renewer.Run()
c.cache.Store(sni, &credentialsCacheElement{
sni: sni,
renewer: renewer,
})
return renewer, nil
}
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