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@@ -0,0 +1,107 @@
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+// Package tlsconfig provides primitives to retrieve secure-enough TLS configurations for both clients and servers.
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+//
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+// As a reminder from https://golang.org/pkg/crypto/tls/#Config:
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+// A Config structure is used to configure a TLS client or server. After one has been passed to a TLS function it must not be modified.
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+// A Config may be reused; the tls package will also not modify it.
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+package tlsconfig
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+
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+import (
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+ "crypto/tls"
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+ "crypto/x509"
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+ "fmt"
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+ "io/ioutil"
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+ "os"
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+
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+ "github.com/Sirupsen/logrus"
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+)
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+
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+// Options represents the information needed to create client and server TLS configurations.
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+type Options struct {
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+ InsecureSkipVerify bool
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+ ClientAuth tls.ClientAuthType
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+ CAFile string
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+ CertFile string
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+ KeyFile string
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+}
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+
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+// Default is a secure-enough TLS configuration.
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+var Default = tls.Config{
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+ // Avoid fallback to SSL protocols < TLS1.0
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+ MinVersion: tls.VersionTLS10,
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+ PreferServerCipherSuites: true,
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+ CipherSuites: []uint16{
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+ tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
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+ tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
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+ tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
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+ tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
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+ tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
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+ tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
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+ tls.TLS_RSA_WITH_AES_128_CBC_SHA,
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+ tls.TLS_RSA_WITH_AES_256_CBC_SHA,
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+ },
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+}
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+
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+// certPool returns an X.509 certificate pool from `caFile`, the certificate file.
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+func certPool(caFile string) (*x509.CertPool, error) {
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+ // If we should verify the server, we need to load a trusted ca
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+ certPool := x509.NewCertPool()
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+ pem, err := ioutil.ReadFile(caFile)
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+ if err != nil {
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+ return nil, fmt.Errorf("Could not read CA certificate %s: %v", caFile, err)
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+ }
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+ if !certPool.AppendCertsFromPEM(pem) {
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+ return nil, fmt.Errorf("failed to append certificates from PEM file: %s", caFile)
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+ }
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+ s := certPool.Subjects()
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+ subjects := make([]string, len(s))
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+ for i, subject := range s {
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+ subjects[i] = string(subject)
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+ }
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+ logrus.Debugf("Trusting certs with subjects: %v", subjects)
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+ return certPool, nil
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+}
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+
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+// Client returns a TLS configuration meant to be used by a client.
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+func Client(options Options) (*tls.Config, error) {
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+ tlsConfig := Default
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+ tlsConfig.InsecureSkipVerify = options.InsecureSkipVerify
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+ if !options.InsecureSkipVerify {
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+ CAs, err := certPool(options.CAFile)
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+ if err != nil {
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+ return nil, err
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+ }
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+ tlsConfig.RootCAs = CAs
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+ }
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+
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+ if options.CertFile != "" && options.KeyFile != "" {
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+ tlsCert, err := tls.LoadX509KeyPair(options.CertFile, options.KeyFile)
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+ if err != nil {
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+ return nil, fmt.Errorf("Could not load X509 key pair: %v. Make sure the key is not encrypted", err)
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+ }
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+ tlsConfig.Certificates = []tls.Certificate{tlsCert}
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+ }
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+
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+ return &tlsConfig, nil
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+}
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+
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+// Server returns a TLS configuration meant to be used by a server.
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+func Server(options Options) (*tls.Config, error) {
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+ tlsConfig := Default
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+ tlsConfig.ClientAuth = options.ClientAuth
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+ tlsCert, err := tls.LoadX509KeyPair(options.CertFile, options.KeyFile)
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+ if err != nil {
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+ if os.IsNotExist(err) {
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+ return nil, fmt.Errorf("Could not load X509 key pair (%s, %s): %v", options.CertFile, options.KeyFile, err)
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+ }
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+ return nil, fmt.Errorf("Error reading X509 key pair (%s, %s): %v. Make sure the key is not encrypted.", options.CertFile, options.KeyFile, err)
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+ }
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+ tlsConfig.Certificates = []tls.Certificate{tlsCert}
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+ if options.ClientAuth >= tls.VerifyClientCertIfGiven {
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+ CAs, err := certPool(options.CAFile)
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+ if err != nil {
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+ return nil, err
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+ }
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+ tlsConfig.ClientCAs = CAs
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+ }
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+ return &tlsConfig, nil
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+}
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Arnaud Porterie