94 lines
2.8 KiB
Go
94 lines
2.8 KiB
Go
// Copyright 2019 The Go Cloud Development Kit 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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// https://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 azuredb contains Wire providers that are common across Azure Database.
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package azuredb
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import (
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"context"
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"crypto/x509"
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"encoding/pem"
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"fmt"
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"io"
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"io/ioutil"
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"net/http"
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"golang.org/x/net/context/ctxhttp"
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)
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const caBundleURL = "https://www.digicert.com/CACerts/BaltimoreCyberTrustRoot.crt.pem"
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// A CertPoolProvider returns a certificate pool that contains the Azure CA certificate.
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type CertPoolProvider interface {
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AzureCertPool(context.Context) (*x509.CertPool, error)
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}
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// CertFetcher pulls the Azure CA certificates from Digicert's servers. The zero
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// value will fetch certificates using the default HTTP client.
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type CertFetcher struct {
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// Client is the HTTP client used to make requests. If nil, then
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// http.DefaultClient is used.
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Client *http.Client
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}
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// AzureCertPool fetches the Azure CA certificates and places them into a pool.
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// It is safe to call from multiple goroutines.
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func (cf *CertFetcher) AzureCertPool(ctx context.Context) (*x509.CertPool, error) {
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certs, err := cf.Fetch(ctx)
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if err != nil {
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return nil, err
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}
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certPool := x509.NewCertPool()
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for _, c := range certs {
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certPool.AddCert(c)
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}
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return certPool, nil
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}
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// Fetch fetches the Azure CA certificates. It is safe to call from multiple goroutines.
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func (cf *CertFetcher) Fetch(ctx context.Context) ([]*x509.Certificate, error) {
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client := cf.Client
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if client == nil {
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client = http.DefaultClient
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}
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resp, err := ctxhttp.Get(ctx, client, caBundleURL)
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if err != nil {
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return nil, fmt.Errorf("fetch Azure certificates: %v", err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("fetch Azure certificates: HTTP %s", resp.Status)
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}
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pemData, err := ioutil.ReadAll(&io.LimitedReader{R: resp.Body, N: 1 << 20}) // limit to 1MiB
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if err != nil {
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return nil, fmt.Errorf("fetch Azure certificates: %v", err)
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}
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var certs []*x509.Certificate
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for len(pemData) > 0 {
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var block *pem.Block
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block, pemData = pem.Decode(pemData)
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if block == nil {
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break
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}
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if block.Type != "CERTIFICATE" || len(block.Headers) != 0 {
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continue
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}
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c, err := x509.ParseCertificate(block.Bytes)
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if err != nil {
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return nil, fmt.Errorf("fetch Azure certificates: %v", err)
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}
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certs = append(certs, c)
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}
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return certs, nil
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}
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