go.crypto/ssh: import gosshnew.

See https://groups.google.com/d/msg/Golang-nuts/AoVxQ4bB5XQ/i8kpMxdbVlEJ

R=hanwen
CC=golang-codereviews
https://golang.org/cl/86190043

ssh/example_test.go

@@ -9,17 +9,23 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	"net"
 	"net/http"
 
 	"code.google.com/p/go.crypto/ssh/terminal"
 )
 
-func ExampleListen() {
+func ExampleNewServerConn() {
 	// An SSH server is represented by a ServerConfig, which holds
 	// certificate details and handles authentication of ServerConns.
 	config := &ServerConfig{
-		PasswordCallback: func(conn *ServerConn, user, pass string) bool {
-			return user == "testuser" && pass == "tiger"
+		PasswordCallback: func(c ConnMetadata, pass []byte) (*Permissions, error) {
+			// Should use constant-time compare (or better, salt+hash) in
+			// a production setting.
+			if c.User() == "testuser" && string(pass) == "tiger" {
+				return nil, nil
+			}
+			return nil, fmt.Errorf("password rejected for %q", c.User())
 		},
 	}
 
@@ -37,50 +43,65 @@ func ExampleListen() {
 
 	// Once a ServerConfig has been configured, connections can be
 	// accepted.
-	listener, err := Listen("tcp", "0.0.0.0:2022", config)
+	listener, err := net.Listen("tcp", "0.0.0.0:2022")
 	if err != nil {
 		panic("failed to listen for connection")
 	}
-	sConn, err := listener.Accept()
+	nConn, err := listener.Accept()
 	if err != nil {
 		panic("failed to accept incoming connection")
 	}
-	if err := sConn.Handshake(); err != nil {
+
+	// Before use, a handshake must be performed on the incoming
+	// net.Conn.
+	_, chans, reqs, err := NewServerConn(nConn, config)
+	if err != nil {
 		panic("failed to handshake")
 	}
+	// The incoming Request channel must be serviced.
+	go DiscardRequests(reqs)
 
-	// A ServerConn multiplexes several channels, which must
-	// themselves be Accepted.
-	for {
-		// Accept reads from the connection, demultiplexes packets
-		// to their corresponding channels and returns when a new
-		// channel request is seen. Some goroutine must always be
-		// calling Accept; otherwise no messages will be forwarded
-		// to the channels.
-		channel, err := sConn.Accept()
-		if err != nil {
-			panic("error from Accept")
-		}
-
+	// Service the incoming Channel channel.
+	for newChannel := range chans {
 		// Channels have a type, depending on the application level
 		// protocol intended. In the case of a shell, the type is
 		// "session" and ServerShell may be used to present a simple
 		// terminal interface.
-		if channel.ChannelType() != "session" {
-			channel.Reject(UnknownChannelType, "unknown channel type")
+		if newChannel.ChannelType() != "session" {
+			newChannel.Reject(UnknownChannelType, "unknown channel type")
 			continue
 		}
-		channel.Accept()
+		channel, requests, err := newChannel.Accept()
+		if err != nil {
+			panic("could not accept channel.")
+		}
+
+		// Sessions have out-of-band requests such as "shell",
+		// "pty-req" and "env".  Here we handle only the
+		// "shell" request.
+		go func(in <-chan *Request) {
+			for req := range in {
+				ok := false
+				switch req.Type {
+				case "shell":
+					ok = true
+					if len(req.Payload) > 0 {
+						// We don't accept any
+						// commands, only the
+						// default shell.
+						ok = false
+					}
+				}
+				req.Reply(ok, nil)
+			}
+		}(requests)
 
 		term := terminal.NewTerminal(channel, "> ")
-		serverTerm := &ServerTerminal{
-			Term:    term,
-			Channel: channel,
-		}
+
 		go func() {
 			defer channel.Close()
 			for {
-				line, err := serverTerm.ReadLine()
+				line, err := term.ReadLine()
 				if err != nil {
 					break
 				}
@@ -95,13 +116,11 @@ func ExampleDial() {
 	// the "password" authentication method is supported.
 	//
 	// To authenticate with the remote server you must pass at least one
-	// implementation of ClientAuth via the Auth field in ClientConfig.
+	// implementation of AuthMethod via the Auth field in ClientConfig.
 	config := &ClientConfig{
 		User: "username",
-		Auth: []ClientAuth{
-			// ClientAuthPassword wraps a ClientPassword implementation
-			// in a type that implements ClientAuth.
-			ClientAuthPassword(password("yourpassword")),
+		Auth: []AuthMethod{
+			Password("yourpassword"),
 		},
 	}
 	client, err := Dial("tcp", "yourserver.com:22", config)
@@ -127,11 +146,11 @@ func ExampleDial() {
 	fmt.Println(b.String())
 }
 
-func ExampleClientConn_Listen() {
+func ExampleClient_Listen() {
 	config := &ClientConfig{
 		User: "username",
-		Auth: []ClientAuth{
-			ClientAuthPassword(password("password")),
+		Auth: []AuthMethod{
+			Password("password"),
 		},
 	}
 	// Dial your ssh server.
@@ -158,8 +177,8 @@ func ExampleSession_RequestPty() {
 	// Create client config
 	config := &ClientConfig{
 		User: "username",
-		Auth: []ClientAuth{
-			ClientAuthPassword(password("password")),
+		Auth: []AuthMethod{
+			Password("password"),
 		},
 	}
 	// Connect to ssh server