mirror of
https://github.com/SagerNet/sing-box.git
synced 2024-11-10 11:03:13 +00:00
96 lines
3.4 KiB
Go
96 lines
3.4 KiB
Go
// Copyright 2022 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package tls
|
|
|
|
import (
|
|
"crypto/x509"
|
|
"runtime"
|
|
"sync"
|
|
"sync/atomic"
|
|
)
|
|
|
|
type cacheEntry struct {
|
|
refs atomic.Int64
|
|
cert *x509.Certificate
|
|
}
|
|
|
|
// certCache implements an intern table for reference counted x509.Certificates,
|
|
// implemented in a similar fashion to BoringSSL's CRYPTO_BUFFER_POOL. This
|
|
// allows for a single x509.Certificate to be kept in memory and referenced from
|
|
// multiple Conns. Returned references should not be mutated by callers. Certificates
|
|
// are still safe to use after they are removed from the cache.
|
|
//
|
|
// Certificates are returned wrapped in a activeCert struct that should be held by
|
|
// the caller. When references to the activeCert are freed, the number of references
|
|
// to the certificate in the cache is decremented. Once the number of references
|
|
// reaches zero, the entry is evicted from the cache.
|
|
//
|
|
// The main difference between this implementation and CRYPTO_BUFFER_POOL is that
|
|
// CRYPTO_BUFFER_POOL is a more generic structure which supports blobs of data,
|
|
// rather than specific structures. Since we only care about x509.Certificates,
|
|
// certCache is implemented as a specific cache, rather than a generic one.
|
|
//
|
|
// See https://boringssl.googlesource.com/boringssl/+/master/include/openssl/pool.h
|
|
// and https://boringssl.googlesource.com/boringssl/+/master/crypto/pool/pool.c
|
|
// for the BoringSSL reference.
|
|
type certCache struct {
|
|
sync.Map
|
|
}
|
|
|
|
var clientCertCache = new(certCache)
|
|
|
|
// activeCert is a handle to a certificate held in the cache. Once there are
|
|
// no alive activeCerts for a given certificate, the certificate is removed
|
|
// from the cache by a finalizer.
|
|
type activeCert struct {
|
|
cert *x509.Certificate
|
|
}
|
|
|
|
// active increments the number of references to the entry, wraps the
|
|
// certificate in the entry in a activeCert, and sets the finalizer.
|
|
//
|
|
// Note that there is a race between active and the finalizer set on the
|
|
// returned activeCert, triggered if active is called after the ref count is
|
|
// decremented such that refs may be > 0 when evict is called. We consider this
|
|
// safe, since the caller holding an activeCert for an entry that is no longer
|
|
// in the cache is fine, with the only side effect being the memory overhead of
|
|
// there being more than one distinct reference to a certificate alive at once.
|
|
func (cc *certCache) active(e *cacheEntry) *activeCert {
|
|
e.refs.Add(1)
|
|
a := &activeCert{e.cert}
|
|
runtime.SetFinalizer(a, func(_ *activeCert) {
|
|
if e.refs.Add(-1) == 0 {
|
|
cc.evict(e)
|
|
}
|
|
})
|
|
return a
|
|
}
|
|
|
|
// evict removes a cacheEntry from the cache.
|
|
func (cc *certCache) evict(e *cacheEntry) {
|
|
cc.Delete(string(e.cert.Raw))
|
|
}
|
|
|
|
// newCert returns a x509.Certificate parsed from der. If there is already a copy
|
|
// of the certificate in the cache, a reference to the existing certificate will
|
|
// be returned. Otherwise, a fresh certificate will be added to the cache, and
|
|
// the reference returned. The returned reference should not be mutated.
|
|
func (cc *certCache) newCert(der []byte) (*activeCert, error) {
|
|
if entry, ok := cc.Load(string(der)); ok {
|
|
return cc.active(entry.(*cacheEntry)), nil
|
|
}
|
|
|
|
cert, err := x509.ParseCertificate(der)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
entry := &cacheEntry{cert: cert}
|
|
if entry, loaded := cc.LoadOrStore(string(der), entry); loaded {
|
|
return cc.active(entry.(*cacheEntry)), nil
|
|
}
|
|
return cc.active(entry), nil
|
|
}
|