mirror of https://github.com/grpc/grpc-go.git
157 lines
4.7 KiB
Go
157 lines
4.7 KiB
Go
/*
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*
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* Copyright 2020 gRPC authors.
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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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*
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*/
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package certprovider
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import (
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"fmt"
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"sync"
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)
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// provStore is the global singleton certificate provider store.
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var provStore = &store{
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providers: make(map[storeKey]*wrappedProvider),
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}
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// storeKey acts as the key to the map of providers maintained by the store. A
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// combination of provider name and configuration is used to uniquely identify
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// every provider instance in the store. Go maps need to be indexed by
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// comparable types, so the provider configuration is converted from
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// `interface{}` to string using the ParseConfig method while creating this key.
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type storeKey struct {
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// name of the certificate provider.
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name string
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// configuration of the certificate provider in string form.
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config string
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// opts contains the certificate name and other keyMaterial options.
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opts BuildOptions
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}
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// wrappedProvider wraps a provider instance with a reference count.
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type wrappedProvider struct {
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Provider
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refCount int
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// A reference to the key and store are also kept here to override the
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// Close method on the provider.
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storeKey storeKey
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store *store
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}
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// store is a collection of provider instances, safe for concurrent access.
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type store struct {
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mu sync.Mutex
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providers map[storeKey]*wrappedProvider
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}
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// Close overrides the Close method of the embedded provider. It releases the
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// reference held by the caller on the underlying provider and if the
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// provider's reference count reaches zero, it is removed from the store, and
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// its Close method is also invoked.
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func (wp *wrappedProvider) Close() {
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ps := wp.store
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ps.mu.Lock()
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defer ps.mu.Unlock()
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wp.refCount--
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if wp.refCount == 0 {
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wp.Provider.Close()
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delete(ps.providers, wp.storeKey)
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}
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}
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// BuildableConfig wraps parsed provider configuration and functionality to
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// instantiate provider instances.
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type BuildableConfig struct {
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name string
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config []byte
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starter func(BuildOptions) Provider
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pStore *store
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}
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// NewBuildableConfig creates a new BuildableConfig with the given arguments.
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// Provider implementations are expected to invoke this function after parsing
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// the given configuration as part of their ParseConfig() method.
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// Equivalent configurations are expected to invoke this function with the same
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// config argument.
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func NewBuildableConfig(name string, config []byte, starter func(BuildOptions) Provider) *BuildableConfig {
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return &BuildableConfig{
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name: name,
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config: config,
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starter: starter,
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pStore: provStore,
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}
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}
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// Build kicks off a provider instance with the wrapped configuration. Multiple
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// invocations of this method with the same opts will result in provider
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// instances being reused.
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func (bc *BuildableConfig) Build(opts BuildOptions) (Provider, error) {
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provStore.mu.Lock()
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defer provStore.mu.Unlock()
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sk := storeKey{
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name: bc.name,
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config: string(bc.config),
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opts: opts,
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}
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if wp, ok := provStore.providers[sk]; ok {
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wp.refCount++
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return wp, nil
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}
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provider := bc.starter(opts)
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if provider == nil {
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return nil, fmt.Errorf("provider(%q, %q).Build(%v) failed", sk.name, sk.config, opts)
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}
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wp := &wrappedProvider{
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Provider: provider,
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refCount: 1,
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storeKey: sk,
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store: provStore,
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}
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provStore.providers[sk] = wp
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return wp, nil
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}
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// String returns the provider name and config as a colon separated string.
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func (bc *BuildableConfig) String() string {
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return fmt.Sprintf("%s:%s", bc.name, string(bc.config))
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}
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// ParseConfig is a convenience function to create a BuildableConfig given a
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// provider name and configuration. Returns an error if there is no registered
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// builder for the given name or if the config parsing fails.
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func ParseConfig(name string, config interface{}) (*BuildableConfig, error) {
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parser := getBuilder(name)
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if parser == nil {
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return nil, fmt.Errorf("no certificate provider builder found for %q", name)
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}
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return parser.ParseConfig(config)
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}
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// GetProvider is a convenience function to create a provider given the name,
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// config and build options.
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func GetProvider(name string, config interface{}, opts BuildOptions) (Provider, error) {
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bc, err := ParseConfig(name, config)
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if err != nil {
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return nil, err
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}
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return bc.Build(opts)
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}
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