Update golang x/crypto dependencies (#2923)

vendor/golang.org/x/crypto/ssh/client.go

@@ -5,15 +5,17 @@
 package ssh
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"net"
+	"os"
 	"sync"
 	"time"
 )
 
 // Client implements a traditional SSH client that supports shells,
-// subprocesses, port forwarding and tunneled dialing.
+// subprocesses, TCP port/streamlocal forwarding and tunneled dialing.
 type Client struct {
 	Conn
 
@@ -40,7 +42,7 @@ func (c *Client) HandleChannelOpen(channelType string) <-chan NewChannel {
 		return nil
 	}
 
-	ch = make(chan NewChannel, 16)
+	ch = make(chan NewChannel, chanSize)
 	c.channelHandlers[channelType] = ch
 	return ch
 }
@@ -59,6 +61,7 @@ func NewClient(c Conn, chans <-chan NewChannel, reqs <-chan *Request) *Client {
 		conn.forwards.closeAll()
 	}()
 	go conn.forwards.handleChannels(conn.HandleChannelOpen("forwarded-tcpip"))
+	go conn.forwards.handleChannels(conn.HandleChannelOpen("forwarded-streamlocal@openssh.com"))
 	return conn
 }
 
@@ -68,6 +71,11 @@ func NewClient(c Conn, chans <-chan NewChannel, reqs <-chan *Request) *Client {
 func NewClientConn(c net.Conn, addr string, config *ClientConfig) (Conn, <-chan NewChannel, <-chan *Request, error) {
 	fullConf := *config
 	fullConf.SetDefaults()
+	if fullConf.HostKeyCallback == nil {
+		c.Close()
+		return nil, nil, nil, errors.New("ssh: must specify HostKeyCallback")
+	}
+
 	conn := &connection{
 		sshConn: sshConn{conn: c},
 	}
@@ -97,13 +105,11 @@ func (c *connection) clientHandshake(dialAddress string, config *ClientConfig) e
 	c.transport = newClientTransport(
 		newTransport(c.sshConn.conn, config.Rand, true /* is client */),
 		c.clientVersion, c.serverVersion, config, dialAddress, c.sshConn.RemoteAddr())
-	if err := c.transport.requestInitialKeyChange(); err != nil {
+	if err := c.transport.waitSession(); err != nil {
 		return err
 	}
 
-	// We just did the key change, so the session ID is established.
 	c.sessionID = c.transport.getSessionID()
-
 	return c.clientAuthenticate(config)
 }
 
@@ -175,6 +181,17 @@ func Dial(network, addr string, config *ClientConfig) (*Client, error) {
 	return NewClient(c, chans, reqs), nil
 }
 
+// HostKeyCallback is the function type used for verifying server
+// keys.  A HostKeyCallback must return nil if the host key is OK, or
+// an error to reject it. It receives the hostname as passed to Dial
+// or NewClientConn. The remote address is the RemoteAddr of the
+// net.Conn underlying the the SSH connection.
+type HostKeyCallback func(hostname string, remote net.Addr, key PublicKey) error
+
+// BannerCallback is the function type used for treat the banner sent by
+// the server. A BannerCallback receives the message sent by the remote server.
+type BannerCallback func(message string) error
+
 // A ClientConfig structure is used to configure a Client. It must not be
 // modified after having been passed to an SSH function.
 type ClientConfig struct {
@@ -190,10 +207,18 @@ type ClientConfig struct {
 	// be used during authentication.
 	Auth []AuthMethod
 
-	// HostKeyCallback, if not nil, is called during the cryptographic
-	// handshake to validate the server's host key. A nil HostKeyCallback
-	// implies that all host keys are accepted.
-	HostKeyCallback func(hostname string, remote net.Addr, key PublicKey) error
+	// HostKeyCallback is called during the cryptographic
+	// handshake to validate the server's host key. The client
+	// configuration must supply this callback for the connection
+	// to succeed. The functions InsecureIgnoreHostKey or
+	// FixedHostKey can be used for simplistic host key checks.
+	HostKeyCallback HostKeyCallback
+
+	// BannerCallback is called during the SSH dance to display a custom
+	// server's message. The client configuration can supply this callback to
+	// handle it as wished. The function BannerDisplayStderr can be used for
+	// simplistic display on Stderr.
+	BannerCallback BannerCallback
 
 	// ClientVersion contains the version identification string that will
 	// be used for the connection. If empty, a reasonable default is used.
@@ -211,3 +236,43 @@ type ClientConfig struct {
 	// A Timeout of zero means no timeout.
 	Timeout time.Duration
 }
+
+// InsecureIgnoreHostKey returns a function that can be used for
+// ClientConfig.HostKeyCallback to accept any host key. It should
+// not be used for production code.
+func InsecureIgnoreHostKey() HostKeyCallback {
+	return func(hostname string, remote net.Addr, key PublicKey) error {
+		return nil
+	}
+}
+
+type fixedHostKey struct {
+	key PublicKey
+}
+
+func (f *fixedHostKey) check(hostname string, remote net.Addr, key PublicKey) error {
+	if f.key == nil {
+		return fmt.Errorf("ssh: required host key was nil")
+	}
+	if !bytes.Equal(key.Marshal(), f.key.Marshal()) {
+		return fmt.Errorf("ssh: host key mismatch")
+	}
+	return nil
+}
+
+// FixedHostKey returns a function for use in
+// ClientConfig.HostKeyCallback to accept only a specific host key.
+func FixedHostKey(key PublicKey) HostKeyCallback {
+	hk := &fixedHostKey{key}
+	return hk.check
+}
+
+// BannerDisplayStderr returns a function that can be used for
+// ClientConfig.BannerCallback to display banners on os.Stderr.
+func BannerDisplayStderr() BannerCallback {
+	return func(banner string) error {
+		_, err := os.Stderr.WriteString(banner)
+
+		return err
+	}
+}