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// Copyright (C) 2022 Andrew Ayer
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
// OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
// Except as contained in this notice, the name(s) of the above copyright
// holders shall not be used in advertising or otherwise to promote the
// sale, use or other dealings in this Software without prior written
// authorization.
package cert
import (
"crypto/tls"
"errors"
"fmt"
"os"
"path/filepath"
"strings"
)
type directory struct {
Path string
Cache *fileCache
}
func (dir *directory) loadCertificate(filename string) (*tls.Certificate, error) {
fullpath := filepath.Join(dir.Path, filename)
if dir.Cache != nil {
return dir.Cache.Load(fullpath)
} else {
return LoadCertificate(fullpath)
}
}
func (dir *directory) GetCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
serverName := hello.ServerName
if serverName == "" {
return nil, errors.New("go-listener: client does not support SNI")
}
if serverName[0] == '.' || strings.IndexByte(hello.ServerName, '/') != -1 {
return nil, errors.New("go-listener: client sent an invalid server name")
}
var serverNameSuffix string
if dot := strings.IndexByte(serverName, '.'); dot != -1 {
serverNameSuffix = serverName[dot:]
}
keyTypes := getSupportedKeyTypes(hello)
if keyTypes.ecdsa {
if cert, err := dir.loadCertificate(serverName + ".pem.ecdsa"); err == nil {
return cert, nil
} else if !os.IsNotExist(err) {
// TODO: log this
}
if cert, err := dir.loadCertificate("_" + serverNameSuffix + ".pem.ecdsa"); err == nil {
return cert, nil
} else if !os.IsNotExist(err) {
// TODO: log this
}
}
if keyTypes.rsa {
if cert, err := dir.loadCertificate(serverName + ".pem.rsa"); err == nil {
return cert, nil
} else if !os.IsNotExist(err) {
// TODO: log this
}
if cert, err := dir.loadCertificate("_" + serverNameSuffix + ".pem.rsa"); err == nil {
return cert, nil
} else if !os.IsNotExist(err) {
// TODO: log this
}
}
if cert, err := dir.loadCertificate(serverName + ".pem"); err == nil {
return cert, nil
} else if !os.IsNotExist(err) {
// TODO: log this
}
if cert, err := dir.loadCertificate("_" + serverNameSuffix + ".pem"); err == nil {
return cert, nil
} else if !os.IsNotExist(err) {
// TODO: log this
}
return nil, fmt.Errorf("go-listener: no certificate found for %q", serverName)
}
// Return a [GetCertificateFunc] that gets the certificate from a file
// in the given directory. The function searches for files in the
// following order:
//
// 1. SERVER_NAME.pem.ecdsa (only if client supports ECDSA certificates)
// 2. WILDCARD_NAME.pem.ecdsa (only if client supports ECDSA certificates)
// 3. SERVER_NAME.pem.rsa (only if client supports RSA certificates)
// 4. WILDCARD_NAME.pem.rsa (only if client supports RSA certificates)
// 5. SERVER_NAME.pem
// 6. WILDCARD_NAME.pem
//
// SERVER_NAME is the SNI hostname provided by the client, and WILDCARD_NAME
// is the SNI hostname with the first label replaced with an underscore
// (e.g. the wildcard name for www.example.com is _.example.com)
//
// Certificate files are cached in memory, and reloaded automatically when they
// change, allowing zero-downtime certificate rotation. See the documentation of
// [LoadCertificate] for the required format of the files.
//
// If no certificate file is found, or if the client does not
// provide an SNI hostname, then the GetCertificateFunc returns an error,
// causing the TLS connection to be terminated. If you need to support clients
// that don't provide SNI, wrap the GetCertificateFunc with
// [GetCertificateDefaultServerName] to specify a default SNI hostname.
func GetCertificateFromDirectory(path string) GetCertificateFunc {
dir := &directory{
Path: path,
Cache: globalFileCache(),
}
return dir.GetCertificate
}
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