98 lines
2.8 KiB
Go
98 lines
2.8 KiB
Go
/*
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Copyright 2023 The Dapr Authors
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package crypto
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import (
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"context"
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"sync"
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"github.com/chebyrash/promise"
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"github.com/lestrrat-go/jwx/v2/jwk"
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kitctx "github.com/dapr/kit/context"
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)
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// GetKeyFn is the type of the getKeyFn function used by the PubKeyCache.
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type GetKeyFn = func(ctx context.Context, key string) func(resolve func(jwk.Key), reject func(error))
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// PubKeyCache implements GetKey with a local cache. We use promises for cache
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// entries so that multiple callers getting the same key at the same time
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// (where the key is not in the cache yet), will result in only a single key
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// fetch.
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// Each cache item uses a context pool so that a key fetch call will only be
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// cancelled once all callers have cancelled their context.
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type PubKeyCache struct {
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getKeyFn GetKeyFn
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pubKeys map[string]pubKeyCacheEntry
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lock sync.Mutex
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}
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type pubKeyCacheEntry struct {
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promise *promise.Promise[jwk.Key]
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ctx *kitctx.Pool
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}
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// NewPubKeyCache returns a new PubKeyCache object
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func NewPubKeyCache(getKeyFn GetKeyFn) *PubKeyCache {
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return &PubKeyCache{
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getKeyFn: getKeyFn,
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pubKeys: make(map[string]pubKeyCacheEntry),
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}
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}
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// GetKey returns a public key from the cache, or uses getKeyFn to request it.
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func (kc *PubKeyCache) GetKey(ctx context.Context, key string) (jwk.Key, error) {
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// Check if the key is in the cache already
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kc.lock.Lock()
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p, ok := kc.pubKeys[key]
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if ok {
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// Add the context to the context pool and return the promise (which may
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// already be resolved).
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kc.pubKeys[key].ctx.Add(ctx)
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kc.lock.Unlock()
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jwkKey, err := p.promise.Await(ctx)
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if err != nil || jwkKey == nil {
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return nil, err
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}
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return *jwkKey, nil
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}
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// Key is not in the cache, create the promise in the cache and return
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// result. Create a new context pool for the promise. Cancel the pool on
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// return so that the context pool doesn't expand indefinitely on cache
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// reads.
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p.ctx = kitctx.NewPool(ctx)
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p.promise = promise.Catch(
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promise.New(kc.getKeyFn(p.ctx, key)),
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p.ctx,
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func(err error) error {
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kc.lock.Lock()
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p.ctx.Cancel()
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delete(kc.pubKeys, key)
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kc.lock.Unlock()
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return err
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},
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)
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kc.pubKeys[key] = p
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kc.lock.Unlock()
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jwkKey, err := p.promise.Await(ctx)
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if err != nil || jwkKey == nil {
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return nil, err
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}
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p.ctx.Cancel()
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return *jwkKey, nil
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}
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