(feat) Add auto-discovery in k8s | Adarsh

vendor/k8s.io/client-go/transport/transport.go

@@ -0,0 +1,227 @@
+/*
+Copyright 2015 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package transport
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+)
+
+// New returns an http.RoundTripper that will provide the authentication
+// or transport level security defined by the provided Config.
+func New(config *Config) (http.RoundTripper, error) {
+	// Set transport level security
+	if config.Transport != nil && (config.HasCA() || config.HasCertAuth() || config.HasCertCallback() || config.TLS.Insecure) {
+		return nil, fmt.Errorf("using a custom transport with TLS certificate options or the insecure flag is not allowed")
+	}
+
+	var (
+		rt  http.RoundTripper
+		err error
+	)
+
+	if config.Transport != nil {
+		rt = config.Transport
+	} else {
+		rt, err = tlsCache.get(config)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return HTTPWrappersForConfig(config, rt)
+}
+
+// TLSConfigFor returns a tls.Config that will provide the transport level security defined
+// by the provided Config. Will return nil if no transport level security is requested.
+func TLSConfigFor(c *Config) (*tls.Config, error) {
+	if !(c.HasCA() || c.HasCertAuth() || c.HasCertCallback() || c.TLS.Insecure || len(c.TLS.ServerName) > 0) {
+		return nil, nil
+	}
+	if c.HasCA() && c.TLS.Insecure {
+		return nil, fmt.Errorf("specifying a root certificates file with the insecure flag is not allowed")
+	}
+	if err := loadTLSFiles(c); err != nil {
+		return nil, err
+	}
+
+	tlsConfig := &tls.Config{
+		// Can't use SSLv3 because of POODLE and BEAST
+		// Can't use TLSv1.0 because of POODLE and BEAST using CBC cipher
+		// Can't use TLSv1.1 because of RC4 cipher usage
+		MinVersion:         tls.VersionTLS12,
+		InsecureSkipVerify: c.TLS.Insecure,
+		ServerName:         c.TLS.ServerName,
+	}
+
+	if c.HasCA() {
+		tlsConfig.RootCAs = rootCertPool(c.TLS.CAData)
+	}
+
+	var staticCert *tls.Certificate
+	if c.HasCertAuth() {
+		// If key/cert were provided, verify them before setting up
+		// tlsConfig.GetClientCertificate.
+		cert, err := tls.X509KeyPair(c.TLS.CertData, c.TLS.KeyData)
+		if err != nil {
+			return nil, err
+		}
+		staticCert = &cert
+	}
+
+	if c.HasCertAuth() || c.HasCertCallback() {
+		tlsConfig.GetClientCertificate = func(*tls.CertificateRequestInfo) (*tls.Certificate, error) {
+			// Note: static key/cert data always take precedence over cert
+			// callback.
+			if staticCert != nil {
+				return staticCert, nil
+			}
+			if c.HasCertCallback() {
+				cert, err := c.TLS.GetCert()
+				if err != nil {
+					return nil, err
+				}
+				// GetCert may return empty value, meaning no cert.
+				if cert != nil {
+					return cert, nil
+				}
+			}
+
+			// Both c.TLS.CertData/KeyData were unset and GetCert didn't return
+			// anything. Return an empty tls.Certificate, no client cert will
+			// be sent to the server.
+			return &tls.Certificate{}, nil
+		}
+	}
+
+	return tlsConfig, nil
+}
+
+// loadTLSFiles copies the data from the CertFile, KeyFile, and CAFile fields into the CertData,
+// KeyData, and CAFile fields, or returns an error. If no error is returned, all three fields are
+// either populated or were empty to start.
+func loadTLSFiles(c *Config) error {
+	var err error
+	c.TLS.CAData, err = dataFromSliceOrFile(c.TLS.CAData, c.TLS.CAFile)
+	if err != nil {
+		return err
+	}
+
+	c.TLS.CertData, err = dataFromSliceOrFile(c.TLS.CertData, c.TLS.CertFile)
+	if err != nil {
+		return err
+	}
+
+	c.TLS.KeyData, err = dataFromSliceOrFile(c.TLS.KeyData, c.TLS.KeyFile)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// dataFromSliceOrFile returns data from the slice (if non-empty), or from the file,
+// or an error if an error occurred reading the file
+func dataFromSliceOrFile(data []byte, file string) ([]byte, error) {
+	if len(data) > 0 {
+		return data, nil
+	}
+	if len(file) > 0 {
+		fileData, err := ioutil.ReadFile(file)
+		if err != nil {
+			return []byte{}, err
+		}
+		return fileData, nil
+	}
+	return nil, nil
+}
+
+// rootCertPool returns nil if caData is empty.  When passed along, this will mean "use system CAs".
+// When caData is not empty, it will be the ONLY information used in the CertPool.
+func rootCertPool(caData []byte) *x509.CertPool {
+	// What we really want is a copy of x509.systemRootsPool, but that isn't exposed.  It's difficult to build (see the go
+	// code for a look at the platform specific insanity), so we'll use the fact that RootCAs == nil gives us the system values
+	// It doesn't allow trusting either/or, but hopefully that won't be an issue
+	if len(caData) == 0 {
+		return nil
+	}
+
+	// if we have caData, use it
+	certPool := x509.NewCertPool()
+	certPool.AppendCertsFromPEM(caData)
+	return certPool
+}
+
+// WrapperFunc wraps an http.RoundTripper when a new transport
+// is created for a client, allowing per connection behavior
+// to be injected.
+type WrapperFunc func(rt http.RoundTripper) http.RoundTripper
+
+// Wrappers accepts any number of wrappers and returns a wrapper
+// function that is the equivalent of calling each of them in order. Nil
+// values are ignored, which makes this function convenient for incrementally
+// wrapping a function.
+func Wrappers(fns ...WrapperFunc) WrapperFunc {
+	if len(fns) == 0 {
+		return nil
+	}
+	// optimize the common case of wrapping a possibly nil transport wrapper
+	// with an additional wrapper
+	if len(fns) == 2 && fns[0] == nil {
+		return fns[1]
+	}
+	return func(rt http.RoundTripper) http.RoundTripper {
+		base := rt
+		for _, fn := range fns {
+			if fn != nil {
+				base = fn(base)
+			}
+		}
+		return base
+	}
+}
+
+// ContextCanceller prevents new requests after the provided context is finished.
+// err is returned when the context is closed, allowing the caller to provide a context
+// appropriate error.
+func ContextCanceller(ctx context.Context, err error) WrapperFunc {
+	return func(rt http.RoundTripper) http.RoundTripper {
+		return &contextCanceller{
+			ctx: ctx,
+			rt:  rt,
+			err: err,
+		}
+	}
+}
+
+type contextCanceller struct {
+	ctx context.Context
+	rt  http.RoundTripper
+	err error
+}
+
+func (b *contextCanceller) RoundTrip(req *http.Request) (*http.Response, error) {
+	select {
+	case <-b.ctx.Done():
+		return nil, b.err
+	default:
+		return b.rt.RoundTrip(req)
+	}
+}