90 lines
2.9 KiB
Go
90 lines
2.9 KiB
Go
/*
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* MinIO Go Library for Amazon S3 Compatible Cloud Storage
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* Copyright 2017 MinIO, Inc.
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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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package credentials
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// A Chain will search for a provider which returns credentials
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// and cache that provider until Retrieve is called again.
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//
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// The Chain provides a way of chaining multiple providers together
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// which will pick the first available using priority order of the
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// Providers in the list.
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//
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// If none of the Providers retrieve valid credentials Value, ChainProvider's
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// Retrieve() will return the no credentials value.
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//
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// If a Provider is found which returns valid credentials Value ChainProvider
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// will cache that Provider for all calls to IsExpired(), until Retrieve is
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// called again after IsExpired() is true.
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//
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// creds := credentials.NewChainCredentials(
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// []credentials.Provider{
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// &credentials.EnvAWSS3{},
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// &credentials.EnvMinio{},
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// })
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//
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// // Usage of ChainCredentials.
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// mc, err := minio.NewWithCredentials(endpoint, creds, secure, "us-east-1")
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// if err != nil {
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// log.Fatalln(err)
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// }
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//
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type Chain struct {
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Providers []Provider
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curr Provider
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}
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// NewChainCredentials returns a pointer to a new Credentials object
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// wrapping a chain of providers.
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func NewChainCredentials(providers []Provider) *Credentials {
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return New(&Chain{
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Providers: append([]Provider{}, providers...),
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})
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}
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// Retrieve returns the credentials value, returns no credentials(anonymous)
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// if no credentials provider returned any value.
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//
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// If a provider is found with credentials, it will be cached and any calls
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// to IsExpired() will return the expired state of the cached provider.
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func (c *Chain) Retrieve() (Value, error) {
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for _, p := range c.Providers {
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creds, _ := p.Retrieve()
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// Always prioritize non-anonymous providers, if any.
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if creds.AccessKeyID == "" && creds.SecretAccessKey == "" {
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continue
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}
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c.curr = p
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return creds, nil
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}
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// At this point we have exhausted all the providers and
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// are left without any credentials return anonymous.
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return Value{
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SignerType: SignatureAnonymous,
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}, nil
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}
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// IsExpired will returned the expired state of the currently cached provider
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// if there is one. If there is no current provider, true will be returned.
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func (c *Chain) IsExpired() bool {
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if c.curr != nil {
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return c.curr.IsExpired()
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}
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return true
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}
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