contexts (gliderlabs#29)

* context: working mostly tested context implementation and refactoring to go with it
* _example/ssh-publickey: updating new context based callbacks
* godocs related to public api changes for contexts
* context: converting []bytes to strings before putting into context

Signed-off-by: Jeff Lindsay <progrium@gmail.com>

_example/ssh-publickey/public_key.go

@@ -16,7 +16,7 @@ func main() {
 		s.Write(authorizedKey)
 	})
 
-	publicKeyOption := ssh.PublicKeyAuth(func(user string, key ssh.PublicKey) bool {
+	publicKeyOption := ssh.PublicKeyAuth(func(ctx ssh.Context, key ssh.PublicKey) bool {
 		return true // allow all keys, or use ssh.KeysEqual() to compare against known keys
 	})
 

context.go

@@ -0,0 +1,142 @@
+package ssh
+
+import (
+	"context"
+	"net"
+
+	gossh "golang.org/x/crypto/ssh"
+)
+
+// contextKey is a value for use with context.WithValue. It's used as
+// a pointer so it fits in an interface{} without allocation.
+type contextKey struct {
+	name string
+}
+
+var (
+	// ContextKeyUser is a context key for use with Contexts in this package.
+	// The associated value will be of type string.
+	ContextKeyUser = &contextKey{"user"}
+
+	// ContextKeySessionID is a context key for use with Contexts in this package.
+	// The associated value will be of type string.
+	ContextKeySessionID = &contextKey{"session-id"}
+
+	// ContextKeyPermissions is a context key for use with Contexts in this package.
+	// The associated value will be of type *Permissions.
+	ContextKeyPermissions = &contextKey{"permissions"}
+
+	// ContextKeyClientVersion is a context key for use with Contexts in this package.
+	// The associated value will be of type string.
+	ContextKeyClientVersion = &contextKey{"client-version"}
+
+	// ContextKeyServerVersion is a context key for use with Contexts in this package.
+	// The associated value will be of type string.
+	ContextKeyServerVersion = &contextKey{"server-version"}
+
+	// ContextKeyLocalAddr is a context key for use with Contexts in this package.
+	// The associated value will be of type net.Addr.
+	ContextKeyLocalAddr = &contextKey{"local-addr"}
+
+	// ContextKeyRemoteAddr is a context key for use with Contexts in this package.
+	// The associated value will be of type net.Addr.
+	ContextKeyRemoteAddr = &contextKey{"remote-addr"}
+
+	// ContextKeyServer is a context key for use with Contexts in this package.
+	// The associated value will be of type *Server.
+	ContextKeyServer = &contextKey{"ssh-server"}
+
+	// ContextKeyPublicKey is a context key for use with Contexts in this package.
+	// The associated value will be of type PublicKey.
+	ContextKeyPublicKey = &contextKey{"public-key"}
+)
+
+// Context is a package specific context interface. It exposes connection
+// metadata and allows new values to be easily written to it. It's used in
+// authentication handlers and callbacks, and its underlying context.Context is
+// exposed on Session in the session Handler.
+type Context interface {
+	context.Context
+
+	// User returns the username used when establishing the SSH connection.
+	User() string
+
+	// SessionID returns the session hash.
+	SessionID() string
+
+	// ClientVersion returns the version reported by the client.
+	ClientVersion() string
+
+	// ServerVersion returns the version reported by the server.
+	ServerVersion() string
+
+	// RemoteAddr returns the remote address for this connection.
+	RemoteAddr() net.Addr
+
+	// LocalAddr returns the local address for this connection.
+	LocalAddr() net.Addr
+
+	// Permissions returns the Permissions object used for this connection.
+	Permissions() *Permissions
+
+	// SetValue allows you to easily write new values into the underlying context.
+	SetValue(key, value interface{})
+}
+
+type sshContext struct {
+	context.Context
+}
+
+func newContext(srv *Server) *sshContext {
+	ctx := &sshContext{context.Background()}
+	ctx.SetValue(ContextKeyServer, srv)
+	perms := &Permissions{&gossh.Permissions{}}
+	ctx.SetValue(ContextKeyPermissions, perms)
+	return ctx
+}
+
+// this is separate from newContext because we will get ConnMetadata
+// at different points so it needs to be applied separately
+func (ctx *sshContext) applyConnMetadata(conn gossh.ConnMetadata) {
+	if ctx.Value(ContextKeySessionID) != nil {
+		return
+	}
+	ctx.SetValue(ContextKeySessionID, string(conn.SessionID()))
+	ctx.SetValue(ContextKeyClientVersion, string(conn.ClientVersion()))
+	ctx.SetValue(ContextKeyServerVersion, string(conn.ServerVersion()))
+	ctx.SetValue(ContextKeyUser, conn.User())
+	ctx.SetValue(ContextKeyLocalAddr, conn.LocalAddr())
+	ctx.SetValue(ContextKeyRemoteAddr, conn.RemoteAddr())
+}
+
+func (ctx *sshContext) SetValue(key, value interface{}) {
+	ctx.Context = context.WithValue(ctx.Context, key, value)
+}
+
+func (ctx *sshContext) User() string {
+	return ctx.Value(ContextKeyUser).(string)
+}
+
+func (ctx *sshContext) SessionID() string {
+	return ctx.Value(ContextKeySessionID).(string)
+}
+
+func (ctx *sshContext) ClientVersion() string {
+	return ctx.Value(ContextKeyClientVersion).(string)
+}
+
+func (ctx *sshContext) ServerVersion() string {
+	return ctx.Value(ContextKeyServerVersion).(string)
+}
+
+func (ctx *sshContext) RemoteAddr() net.Addr {
+	return ctx.Value(ContextKeyRemoteAddr).(net.Addr)
+}
+
+func (ctx *sshContext) LocalAddr() net.Addr {
+	return ctx.Value(ContextKeyLocalAddr).(net.Addr)
+}
+
+func (ctx *sshContext) Permissions() *Permissions {
+	return ctx.Value(ContextKeyPermissions).(*Permissions)
+}

context_test.go

@@ -0,0 +1,47 @@
+package ssh
+
+import "testing"
+
+func TestSetPermissions(t *testing.T) {
+	t.Parallel()
+	permsExt := map[string]string{
+		"foo": "bar",
+	}
+	session, cleanup := newTestSessionWithOptions(t, &Server{
+		Handler: func(s Session) {
+			if _, ok := s.Permissions().Extensions["foo"]; !ok {
+				t.Fatalf("got %#v; want %#v", s.Permissions().Extensions, permsExt)
+			}
+		},
+	}, nil, PasswordAuth(func(ctx Context, password string) bool {
+		ctx.Permissions().Extensions = permsExt
+		return true
+	}))
+	defer cleanup()
+	if err := session.Run(""); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSetValue(t *testing.T) {
+	t.Parallel()
+	value := map[string]string{
+		"foo": "bar",
+	}
+	key := "testValue"
+	session, cleanup := newTestSessionWithOptions(t, &Server{
+		Handler: func(s Session) {
+			v := s.Context().Value(key).(map[string]string)
+			if v["foo"] != value["foo"] {
+				t.Fatalf("got %#v; want %#v", v, value)
+			}
+		},
+	}, nil, PasswordAuth(func(ctx Context, password string) bool {
+		ctx.SetValue(key, value)
+		return true
+	}))
+	defer cleanup()
+	if err := session.Run(""); err != nil {
+		t.Fatal(err)
+	}
+}

example_test.go

@@ -15,7 +15,7 @@ func ExampleListenAndServe() {
 
 func ExamplePasswordAuth() {
 	ssh.ListenAndServe(":2222", nil,
-		ssh.PasswordAuth(func(user, pass string) bool {
+		ssh.PasswordAuth(func(ctx ssh.Context, pass string) bool {
 			return pass == "secret"
 		}),
 	)
@@ -27,7 +27,7 @@ func ExampleNoPty() {
 
 func ExamplePublicKeyAuth() {
 	ssh.ListenAndServe(":2222", nil,
-		ssh.PublicKeyAuth(func(user string, key ssh.PublicKey) bool {
+		ssh.PublicKeyAuth(func(ctx ssh.Context, key ssh.PublicKey) bool {
 			data, _ := ioutil.ReadFile("/path/to/allowed/key.pub")
 			allowed, _, _, _, _ := ssh.ParseAuthorizedKey(data)
 			return ssh.KeysEqual(key, allowed)

options.go

@@ -56,7 +56,7 @@ func HostKeyPEM(bytes []byte) Option {
 // denying PTY requests.
 func NoPty() Option {
 	return func(srv *Server) error {
-		srv.PtyCallback = func(user string, permissions *Permissions) bool {
+		srv.PtyCallback = func(ctx Context, pty Pty) bool {
 			return false
 		}
 		return nil

options_test.go

@@ -0,0 +1,66 @@
+package ssh
+
+import (
+	"strings"
+	"testing"
+
+	gossh "golang.org/x/crypto/ssh"
+)
+
+func newTestSessionWithOptions(t *testing.T, srv *Server, cfg *gossh.ClientConfig, options ...Option) (*gossh.Session, func()) {
+	for _, option := range options {
+		if err := srv.SetOption(option); err != nil {
+			t.Fatal(err)
+		}
+	}
+	return newTestSession(t, srv, cfg)
+}
+
+func TestPasswordAuth(t *testing.T) {
+	t.Parallel()
+	testUser := "testuser"
+	testPass := "testpass"
+	session, cleanup := newTestSessionWithOptions(t, &Server{
+		Handler: func(s Session) {
+			// noop
+		},
+	}, &gossh.ClientConfig{
+		User: testUser,
+		Auth: []gossh.AuthMethod{
+			gossh.Password(testPass),
+		},
+	}, PasswordAuth(func(ctx Context, password string) bool {
+		if ctx.User() != testUser {
+			t.Fatalf("user = %#v; want %#v", ctx.User(), testUser)
+		}
+		if password != testPass {
+			t.Fatalf("user = %#v; want %#v", password, testPass)
+		}
+		return true
+	}))
+	defer cleanup()
+	if err := session.Run(""); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestPasswordAuthBadPass(t *testing.T) {
+	t.Parallel()
+	l := newLocalListener()
+	srv := &Server{Handler: func(s Session) {}}
+	srv.SetOption(PasswordAuth(func(ctx Context, password string) bool {
+		return false
+	}))
+	go srv.serveOnce(l)
+	_, err := gossh.Dial("tcp", l.Addr().String(), &gossh.ClientConfig{
+		User: "testuser",
+		Auth: []gossh.AuthMethod{
+			gossh.Password("testpass"),
+		},
+	})
+	if err != nil {
+		if !strings.Contains(err.Error(), "unable to authenticate") {
+			t.Fatal(err)
+		}
+	}
+}