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* use certmagic for more extensible/robust ACME cert handling * accept TOS based on config option Signed-off-by: Andrew Thornton <art27@cantab.net> Co-authored-by: zeripath <art27@cantab.net> Co-authored-by: Lauris BH <lauris@nix.lv>
327 lines
10 KiB
Go
Vendored
327 lines
10 KiB
Go
Vendored
// Copyright 2015 Matthew Holt
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package certmagic
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import (
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"fmt"
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weakrand "math/rand" // seeded elsewhere
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"strings"
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"sync"
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"time"
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"go.uber.org/zap"
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)
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// Cache is a structure that stores certificates in memory.
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// A Cache indexes certificates by name for quick access
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// during TLS handshakes, and avoids duplicating certificates
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// in memory. Generally, there should only be one per process.
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// However, that is not a strict requirement; but using more
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// than one is a code smell, and may indicate an
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// over-engineered design.
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//
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// An empty cache is INVALID and must not be used. Be sure
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// to call NewCache to get a valid value.
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//
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// These should be very long-lived values and must not be
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// copied. Before all references leave scope to be garbage
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// collected, ensure you call Stop() to stop maintenance on
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// the certificates stored in this cache and release locks.
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//
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// Caches are not usually manipulated directly; create a
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// Config value with a pointer to a Cache, and then use
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// the Config to interact with the cache. Caches are
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// agnostic of any particular storage or ACME config,
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// since each certificate may be managed and stored
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// differently.
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type Cache struct {
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// User configuration of the cache
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options CacheOptions
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// The cache is keyed by certificate hash
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cache map[string]Certificate
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// cacheIndex is a map of SAN to cache key (cert hash)
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cacheIndex map[string][]string
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// Protects the cache and index maps
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mu sync.RWMutex
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// Close this channel to cancel asset maintenance
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stopChan chan struct{}
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// Used to signal when stopping is completed
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doneChan chan struct{}
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logger *zap.Logger
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}
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// NewCache returns a new, valid Cache for efficiently
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// accessing certificates in memory. It also begins a
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// maintenance goroutine to tend to the certificates
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// in the cache. Call Stop() when you are done with the
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// cache so it can clean up locks and stuff.
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//
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// Most users of this package will not need to call this
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// because a default certificate cache is created for you.
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// Only advanced use cases require creating a new cache.
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//
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// This function panics if opts.GetConfigForCert is not
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// set. The reason is that a cache absolutely needs to
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// be able to get a Config with which to manage TLS
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// assets, and it is not safe to assume that the Default
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// config is always the correct one, since you have
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// created the cache yourself.
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//
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// See the godoc for Cache to use it properly. When
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// no longer needed, caches should be stopped with
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// Stop() to clean up resources even if the process
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// is being terminated, so that it can clean up
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// any locks for other processes to unblock!
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func NewCache(opts CacheOptions) *Cache {
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// assume default options if necessary
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if opts.OCSPCheckInterval <= 0 {
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opts.OCSPCheckInterval = DefaultOCSPCheckInterval
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}
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if opts.RenewCheckInterval <= 0 {
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opts.RenewCheckInterval = DefaultRenewCheckInterval
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}
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if opts.Capacity < 0 {
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opts.Capacity = 0
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}
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// this must be set, because we cannot not
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// safely assume that the Default Config
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// is always the correct one to use
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if opts.GetConfigForCert == nil {
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panic("cache must be initialized with a GetConfigForCert callback")
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}
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c := &Cache{
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options: opts,
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cache: make(map[string]Certificate),
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cacheIndex: make(map[string][]string),
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stopChan: make(chan struct{}),
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doneChan: make(chan struct{}),
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logger: opts.Logger,
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}
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go c.maintainAssets(0)
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return c
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}
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// Stop stops the maintenance goroutine for
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// certificates in certCache. It blocks until
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// stopping is complete. Once a cache is
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// stopped, it cannot be reused.
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func (certCache *Cache) Stop() {
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close(certCache.stopChan) // signal to stop
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<-certCache.doneChan // wait for stop to complete
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}
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// CacheOptions is used to configure certificate caches.
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// Once a cache has been created with certain options,
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// those settings cannot be changed.
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type CacheOptions struct {
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// REQUIRED. A function that returns a configuration
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// used for managing a certificate, or for accessing
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// that certificate's asset storage (e.g. for
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// OCSP staples, etc). The returned Config MUST
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// be associated with the same Cache as the caller.
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//
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// The reason this is a callback function, dynamically
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// returning a Config (instead of attaching a static
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// pointer to a Config on each certificate) is because
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// the config for how to manage a domain's certificate
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// might change from maintenance to maintenance. The
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// cache is so long-lived, we cannot assume that the
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// host's situation will always be the same; e.g. the
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// certificate might switch DNS providers, so the DNS
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// challenge (if used) would need to be adjusted from
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// the last time it was run ~8 weeks ago.
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GetConfigForCert ConfigGetter
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// How often to check certificates for renewal;
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// if unset, DefaultOCSPCheckInterval will be used.
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OCSPCheckInterval time.Duration
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// How often to check certificates for renewal;
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// if unset, DefaultRenewCheckInterval will be used.
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RenewCheckInterval time.Duration
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// Maximum number of certificates to allow in the cache.
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// If reached, certificates will be randomly evicted to
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// make room for new ones. 0 means unlimited.
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Capacity int
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// Set a logger to enable logging
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Logger *zap.Logger
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}
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// ConfigGetter is a function that returns a prepared,
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// valid config that should be used when managing the
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// given certificate or its assets.
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type ConfigGetter func(Certificate) (*Config, error)
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// cacheCertificate calls unsyncedCacheCertificate with a write lock.
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//
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// This function is safe for concurrent use.
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func (certCache *Cache) cacheCertificate(cert Certificate) {
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certCache.mu.Lock()
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certCache.unsyncedCacheCertificate(cert)
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certCache.mu.Unlock()
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}
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// unsyncedCacheCertificate adds cert to the in-memory cache unless
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// it already exists in the cache (according to cert.Hash). It
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// updates the name index.
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//
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// This function is NOT safe for concurrent use. Callers MUST acquire
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// a write lock on certCache.mu first.
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func (certCache *Cache) unsyncedCacheCertificate(cert Certificate) {
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// no-op if this certificate already exists in the cache
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if _, ok := certCache.cache[cert.hash]; ok {
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return
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}
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// if the cache is at capacity, make room for new cert
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cacheSize := len(certCache.cache)
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if certCache.options.Capacity > 0 && cacheSize >= certCache.options.Capacity {
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// Go maps are "nondeterministic" but not actually random,
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// so although we could just chop off the "front" of the
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// map with less code, that is a heavily skewed eviction
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// strategy; generating random numbers is cheap and
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// ensures a much better distribution.
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rnd := weakrand.Intn(cacheSize)
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i := 0
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for _, randomCert := range certCache.cache {
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if i == rnd {
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certCache.removeCertificate(randomCert)
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break
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}
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i++
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}
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}
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// store the certificate
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certCache.cache[cert.hash] = cert
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// update the index so we can access it by name
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for _, name := range cert.Names {
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certCache.cacheIndex[name] = append(certCache.cacheIndex[name], cert.hash)
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}
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}
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// removeCertificate removes cert from the cache.
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//
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// This function is NOT safe for concurrent use; callers
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// MUST first acquire a write lock on certCache.mu.
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func (certCache *Cache) removeCertificate(cert Certificate) {
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// delete all mentions of this cert from the name index
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for _, name := range cert.Names {
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keyList := certCache.cacheIndex[name]
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for i, cacheKey := range keyList {
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if cacheKey == cert.hash {
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keyList = append(keyList[:i], keyList[i+1:]...)
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}
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}
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if len(keyList) == 0 {
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delete(certCache.cacheIndex, name)
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} else {
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certCache.cacheIndex[name] = keyList
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}
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}
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// delete the actual cert from the cache
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delete(certCache.cache, cert.hash)
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}
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// replaceCertificate atomically replaces oldCert with newCert in
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// the cache.
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//
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// This method is safe for concurrent use.
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func (certCache *Cache) replaceCertificate(oldCert, newCert Certificate) {
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certCache.mu.Lock()
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certCache.removeCertificate(oldCert)
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certCache.unsyncedCacheCertificate(newCert)
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certCache.mu.Unlock()
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if certCache.logger != nil {
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certCache.logger.Info("replaced certificate in cache",
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zap.Strings("identifiers", newCert.Names),
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zap.Time("new_expiration", newCert.Leaf.NotAfter))
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}
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}
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func (certCache *Cache) getAllMatchingCerts(name string) []Certificate {
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certCache.mu.RLock()
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defer certCache.mu.RUnlock()
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allCertKeys := certCache.cacheIndex[name]
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certs := make([]Certificate, len(allCertKeys))
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for i := range allCertKeys {
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certs[i] = certCache.cache[allCertKeys[i]]
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}
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return certs
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}
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func (certCache *Cache) getAllCerts() []Certificate {
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certCache.mu.RLock()
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defer certCache.mu.RUnlock()
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certs := make([]Certificate, 0, len(certCache.cache))
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for _, cert := range certCache.cache {
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certs = append(certs, cert)
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}
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return certs
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}
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func (certCache *Cache) getConfig(cert Certificate) (*Config, error) {
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cfg, err := certCache.options.GetConfigForCert(cert)
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if err != nil {
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return nil, err
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}
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if cfg.certCache != nil && cfg.certCache != certCache {
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return nil, fmt.Errorf("config returned for certificate %v is not nil and points to different cache; got %p, expected %p (this one)",
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cert.Names, cfg.certCache, certCache)
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}
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return cfg, nil
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}
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// AllMatchingCertificates returns a list of all certificates that could
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// be used to serve the given SNI name, including exact SAN matches and
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// wildcard matches.
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func (certCache *Cache) AllMatchingCertificates(name string) []Certificate {
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// get exact matches first
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certs := certCache.getAllMatchingCerts(name)
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// then look for wildcard matches by replacing each
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// label of the domain name with wildcards
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labels := strings.Split(name, ".")
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for i := range labels {
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labels[i] = "*"
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candidate := strings.Join(labels, ".")
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certs = append(certs, certCache.getAllMatchingCerts(candidate)...)
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}
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return certs
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}
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var (
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defaultCache *Cache
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defaultCacheMu sync.Mutex
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)
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