Adding upstream version 1.16.10.upstream/1.16.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1143 insertions, 0 deletions

diff --git a/src/net/smtp/smtp_test.go b/src/net/smtp/smtp_test.go
new file mode 100644
index 0000000..5521937
--- /dev/null
+++ b/src/net/smtp/smtp_test.go
@@ -0,0 +1,1143 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package smtp
+
+import (
+	"bufio"
+	"bytes"
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"internal/testenv"
+	"io"
+	"net"
+	"net/textproto"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+)
+
+type authTest struct {
+	auth       Auth
+	challenges []string
+	name       string
+	responses  []string
+}
+
+var authTests = []authTest{
+	{PlainAuth("", "user", "pass", "testserver"), []string{}, "PLAIN", []string{"\x00user\x00pass"}},
+	{PlainAuth("foo", "bar", "baz", "testserver"), []string{}, "PLAIN", []string{"foo\x00bar\x00baz"}},
+	{CRAMMD5Auth("user", "pass"), []string{"<123456.1322876914@testserver>"}, "CRAM-MD5", []string{"", "user 287eb355114cf5c471c26a875f1ca4ae"}},
+}
+
+func TestAuth(t *testing.T) {
+testLoop:
+	for i, test := range authTests {
+		name, resp, err := test.auth.Start(&ServerInfo{"testserver", true, nil})
+		if name != test.name {
+			t.Errorf("#%d got name %s, expected %s", i, name, test.name)
+		}
+		if !bytes.Equal(resp, []byte(test.responses[0])) {
+			t.Errorf("#%d got response %s, expected %s", i, resp, test.responses[0])
+		}
+		if err != nil {
+			t.Errorf("#%d error: %s", i, err)
+		}
+		for j := range test.challenges {
+			challenge := []byte(test.challenges[j])
+			expected := []byte(test.responses[j+1])
+			resp, err := test.auth.Next(challenge, true)
+			if err != nil {
+				t.Errorf("#%d error: %s", i, err)
+				continue testLoop
+			}
+			if !bytes.Equal(resp, expected) {
+				t.Errorf("#%d got %s, expected %s", i, resp, expected)
+				continue testLoop
+			}
+		}
+	}
+}
+
+func TestAuthPlain(t *testing.T) {
+
+	tests := []struct {
+		authName string
+		server   *ServerInfo
+		err      string
+	}{
+		{
+			authName: "servername",
+			server:   &ServerInfo{Name: "servername", TLS: true},
+		},
+		{
+			// OK to use PlainAuth on localhost without TLS
+			authName: "localhost",
+			server:   &ServerInfo{Name: "localhost", TLS: false},
+		},
+		{
+			// NOT OK on non-localhost, even if server says PLAIN is OK.
+			// (We don't know that the server is the real server.)
+			authName: "servername",
+			server:   &ServerInfo{Name: "servername", Auth: []string{"PLAIN"}},
+			err:      "unencrypted connection",
+		},
+		{
+			authName: "servername",
+			server:   &ServerInfo{Name: "servername", Auth: []string{"CRAM-MD5"}},
+			err:      "unencrypted connection",
+		},
+		{
+			authName: "servername",
+			server:   &ServerInfo{Name: "attacker", TLS: true},
+			err:      "wrong host name",
+		},
+	}
+	for i, tt := range tests {
+		auth := PlainAuth("foo", "bar", "baz", tt.authName)
+		_, _, err := auth.Start(tt.server)
+		got := ""
+		if err != nil {
+			got = err.Error()
+		}
+		if got != tt.err {
+			t.Errorf("%d. got error = %q; want %q", i, got, tt.err)
+		}
+	}
+}
+
+// Issue 17794: don't send a trailing space on AUTH command when there's no password.
+func TestClientAuthTrimSpace(t *testing.T) {
+	server := "220 hello world\r\n" +
+		"200 some more"
+	var wrote bytes.Buffer
+	var fake faker
+	fake.ReadWriter = struct {
+		io.Reader
+		io.Writer
+	}{
+		strings.NewReader(server),
+		&wrote,
+	}
+	c, err := NewClient(fake, "fake.host")
+	if err != nil {
+		t.Fatalf("NewClient: %v", err)
+	}
+	c.tls = true
+	c.didHello = true
+	c.Auth(toServerEmptyAuth{})
+	c.Close()
+	if got, want := wrote.String(), "AUTH FOOAUTH\r\n*\r\nQUIT\r\n"; got != want {
+		t.Errorf("wrote %q; want %q", got, want)
+	}
+}
+
+// toServerEmptyAuth is an implementation of Auth that only implements
+// the Start method, and returns "FOOAUTH", nil, nil. Notably, it returns
+// zero bytes for "toServer" so we can test that we don't send spaces at
+// the end of the line. See TestClientAuthTrimSpace.
+type toServerEmptyAuth struct{}
+
+func (toServerEmptyAuth) Start(server *ServerInfo) (proto string, toServer []byte, err error) {
+	return "FOOAUTH", nil, nil
+}
+
+func (toServerEmptyAuth) Next(fromServer []byte, more bool) (toServer []byte, err error) {
+	panic("unexpected call")
+}
+
+type faker struct {
+	io.ReadWriter
+}
+
+func (f faker) Close() error                     { return nil }
+func (f faker) LocalAddr() net.Addr              { return nil }
+func (f faker) RemoteAddr() net.Addr             { return nil }
+func (f faker) SetDeadline(time.Time) error      { return nil }
+func (f faker) SetReadDeadline(time.Time) error  { return nil }
+func (f faker) SetWriteDeadline(time.Time) error { return nil }
+
+func TestBasic(t *testing.T) {
+	server := strings.Join(strings.Split(basicServer, "\n"), "\r\n")
+	client := strings.Join(strings.Split(basicClient, "\n"), "\r\n")
+
+	var cmdbuf bytes.Buffer
+	bcmdbuf := bufio.NewWriter(&cmdbuf)
+	var fake faker
+	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
+	c := &Client{Text: textproto.NewConn(fake), localName: "localhost"}
+
+	if err := c.helo(); err != nil {
+		t.Fatalf("HELO failed: %s", err)
+	}
+	if err := c.ehlo(); err == nil {
+		t.Fatalf("Expected first EHLO to fail")
+	}
+	if err := c.ehlo(); err != nil {
+		t.Fatalf("Second EHLO failed: %s", err)
+	}
+
+	c.didHello = true
+	if ok, args := c.Extension("aUtH"); !ok || args != "LOGIN PLAIN" {
+		t.Fatalf("Expected AUTH supported")
+	}
+	if ok, _ := c.Extension("DSN"); ok {
+		t.Fatalf("Shouldn't support DSN")
+	}
+
+	if err := c.Mail("user@gmail.com"); err == nil {
+		t.Fatalf("MAIL should require authentication")
+	}
+
+	if err := c.Verify("user1@gmail.com"); err == nil {
+		t.Fatalf("First VRFY: expected no verification")
+	}
+	if err := c.Verify("user2@gmail.com>\r\nDATA\r\nAnother injected message body\r\n.\r\nQUIT\r\n"); err == nil {
+		t.Fatalf("VRFY should have failed due to a message injection attempt")
+	}
+	if err := c.Verify("user2@gmail.com"); err != nil {
+		t.Fatalf("Second VRFY: expected verification, got %s", err)
+	}
+
+	// fake TLS so authentication won't complain
+	c.tls = true
+	c.serverName = "smtp.google.com"
+	if err := c.Auth(PlainAuth("", "user", "pass", "smtp.google.com")); err != nil {
+		t.Fatalf("AUTH failed: %s", err)
+	}
+
+	if err := c.Rcpt("golang-nuts@googlegroups.com>\r\nDATA\r\nInjected message body\r\n.\r\nQUIT\r\n"); err == nil {
+		t.Fatalf("RCPT should have failed due to a message injection attempt")
+	}
+	if err := c.Mail("user@gmail.com>\r\nDATA\r\nAnother injected message body\r\n.\r\nQUIT\r\n"); err == nil {
+		t.Fatalf("MAIL should have failed due to a message injection attempt")
+	}
+	if err := c.Mail("user@gmail.com"); err != nil {
+		t.Fatalf("MAIL failed: %s", err)
+	}
+	if err := c.Rcpt("golang-nuts@googlegroups.com"); err != nil {
+		t.Fatalf("RCPT failed: %s", err)
+	}
+	msg := `From: user@gmail.com
+To: golang-nuts@googlegroups.com
+Subject: Hooray for Go
+
+Line 1
+.Leading dot line .
+Goodbye.`
+	w, err := c.Data()
+	if err != nil {
+		t.Fatalf("DATA failed: %s", err)
+	}
+	if _, err := w.Write([]byte(msg)); err != nil {
+		t.Fatalf("Data write failed: %s", err)
+	}
+	if err := w.Close(); err != nil {
+		t.Fatalf("Bad data response: %s", err)
+	}
+
+	if err := c.Quit(); err != nil {
+		t.Fatalf("QUIT failed: %s", err)
+	}
+
+	bcmdbuf.Flush()
+	actualcmds := cmdbuf.String()
+	if client != actualcmds {
+		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+	}
+}
+
+var basicServer = `250 mx.google.com at your service
+502 Unrecognized command.
+250-mx.google.com at your service
+250-SIZE 35651584
+250-AUTH LOGIN PLAIN
+250 8BITMIME
+530 Authentication required
+252 Send some mail, I'll try my best
+250 User is valid
+235 Accepted
+250 Sender OK
+250 Receiver OK
+354 Go ahead
+250 Data OK
+221 OK
+`
+
+var basicClient = `HELO localhost
+EHLO localhost
+EHLO localhost
+MAIL FROM:<user@gmail.com> BODY=8BITMIME
+VRFY user1@gmail.com
+VRFY user2@gmail.com
+AUTH PLAIN AHVzZXIAcGFzcw==
+MAIL FROM:<user@gmail.com> BODY=8BITMIME
+RCPT TO:<golang-nuts@googlegroups.com>
+DATA
+From: user@gmail.com
+To: golang-nuts@googlegroups.com
+Subject: Hooray for Go
+
+Line 1
+..Leading dot line .
+Goodbye.
+.
+QUIT
+`
+
+func TestExtensions(t *testing.T) {
+	fake := func(server string) (c *Client, bcmdbuf *bufio.Writer, cmdbuf *strings.Builder) {
+		server = strings.Join(strings.Split(server, "\n"), "\r\n")
+
+		cmdbuf = &strings.Builder{}
+		bcmdbuf = bufio.NewWriter(cmdbuf)
+		var fake faker
+		fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
+		c = &Client{Text: textproto.NewConn(fake), localName: "localhost"}
+
+		return c, bcmdbuf, cmdbuf
+	}
+
+	t.Run("helo", func(t *testing.T) {
+		const (
+			basicServer = `250 mx.google.com at your service
+250 Sender OK
+221 Goodbye
+`
+
+			basicClient = `HELO localhost
+MAIL FROM:<user@gmail.com>
+QUIT
+`
+		)
+
+		c, bcmdbuf, cmdbuf := fake(basicServer)
+
+		if err := c.helo(); err != nil {
+			t.Fatalf("HELO failed: %s", err)
+		}
+		c.didHello = true
+		if err := c.Mail("user@gmail.com"); err != nil {
+			t.Fatalf("MAIL FROM failed: %s", err)
+		}
+		if err := c.Quit(); err != nil {
+			t.Fatalf("QUIT failed: %s", err)
+		}
+
+		bcmdbuf.Flush()
+		actualcmds := cmdbuf.String()
+		client := strings.Join(strings.Split(basicClient, "\n"), "\r\n")
+		if client != actualcmds {
+			t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+		}
+	})
+
+	t.Run("ehlo", func(t *testing.T) {
+		const (
+			basicServer = `250-mx.google.com at your service
+250 SIZE 35651584
+250 Sender OK
+221 Goodbye
+`
+
+			basicClient = `EHLO localhost
+MAIL FROM:<user@gmail.com>
+QUIT
+`
+		)
+
+		c, bcmdbuf, cmdbuf := fake(basicServer)
+
+		if err := c.Hello("localhost"); err != nil {
+			t.Fatalf("EHLO failed: %s", err)
+		}
+		if ok, _ := c.Extension("8BITMIME"); ok {
+			t.Fatalf("Shouldn't support 8BITMIME")
+		}
+		if ok, _ := c.Extension("SMTPUTF8"); ok {
+			t.Fatalf("Shouldn't support SMTPUTF8")
+		}
+		if err := c.Mail("user@gmail.com"); err != nil {
+			t.Fatalf("MAIL FROM failed: %s", err)
+		}
+		if err := c.Quit(); err != nil {
+			t.Fatalf("QUIT failed: %s", err)
+		}
+
+		bcmdbuf.Flush()
+		actualcmds := cmdbuf.String()
+		client := strings.Join(strings.Split(basicClient, "\n"), "\r\n")
+		if client != actualcmds {
+			t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+		}
+	})
+
+	t.Run("ehlo 8bitmime", func(t *testing.T) {
+		const (
+			basicServer = `250-mx.google.com at your service
+250-SIZE 35651584
+250 8BITMIME
+250 Sender OK
+221 Goodbye
+`
+
+			basicClient = `EHLO localhost
+MAIL FROM:<user@gmail.com> BODY=8BITMIME
+QUIT
+`
+		)
+
+		c, bcmdbuf, cmdbuf := fake(basicServer)
+
+		if err := c.Hello("localhost"); err != nil {
+			t.Fatalf("EHLO failed: %s", err)
+		}
+		if ok, _ := c.Extension("8BITMIME"); !ok {
+			t.Fatalf("Should support 8BITMIME")
+		}
+		if ok, _ := c.Extension("SMTPUTF8"); ok {
+			t.Fatalf("Shouldn't support SMTPUTF8")
+		}
+		if err := c.Mail("user@gmail.com"); err != nil {
+			t.Fatalf("MAIL FROM failed: %s", err)
+		}
+		if err := c.Quit(); err != nil {
+			t.Fatalf("QUIT failed: %s", err)
+		}
+
+		bcmdbuf.Flush()
+		actualcmds := cmdbuf.String()
+		client := strings.Join(strings.Split(basicClient, "\n"), "\r\n")
+		if client != actualcmds {
+			t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+		}
+	})
+
+	t.Run("ehlo smtputf8", func(t *testing.T) {
+		const (
+			basicServer = `250-mx.google.com at your service
+250-SIZE 35651584
+250 SMTPUTF8
+250 Sender OK
+221 Goodbye
+`
+
+			basicClient = `EHLO localhost
+MAIL FROM:<user+📧@gmail.com> SMTPUTF8
+QUIT
+`
+		)
+
+		c, bcmdbuf, cmdbuf := fake(basicServer)
+
+		if err := c.Hello("localhost"); err != nil {
+			t.Fatalf("EHLO failed: %s", err)
+		}
+		if ok, _ := c.Extension("8BITMIME"); ok {
+			t.Fatalf("Shouldn't support 8BITMIME")
+		}
+		if ok, _ := c.Extension("SMTPUTF8"); !ok {
+			t.Fatalf("Should support SMTPUTF8")
+		}
+		if err := c.Mail("user+📧@gmail.com"); err != nil {
+			t.Fatalf("MAIL FROM failed: %s", err)
+		}
+		if err := c.Quit(); err != nil {
+			t.Fatalf("QUIT failed: %s", err)
+		}
+
+		bcmdbuf.Flush()
+		actualcmds := cmdbuf.String()
+		client := strings.Join(strings.Split(basicClient, "\n"), "\r\n")
+		if client != actualcmds {
+			t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+		}
+	})
+
+	t.Run("ehlo 8bitmime smtputf8", func(t *testing.T) {
+		const (
+			basicServer = `250-mx.google.com at your service
+250-SIZE 35651584
+250-8BITMIME
+250 SMTPUTF8
+250 Sender OK
+221 Goodbye
+	`
+
+			basicClient = `EHLO localhost
+MAIL FROM:<user+📧@gmail.com> BODY=8BITMIME SMTPUTF8
+QUIT
+`
+		)
+
+		c, bcmdbuf, cmdbuf := fake(basicServer)
+
+		if err := c.Hello("localhost"); err != nil {
+			t.Fatalf("EHLO failed: %s", err)
+		}
+		c.didHello = true
+		if ok, _ := c.Extension("8BITMIME"); !ok {
+			t.Fatalf("Should support 8BITMIME")
+		}
+		if ok, _ := c.Extension("SMTPUTF8"); !ok {
+			t.Fatalf("Should support SMTPUTF8")
+		}
+		if err := c.Mail("user+📧@gmail.com"); err != nil {
+			t.Fatalf("MAIL FROM failed: %s", err)
+		}
+		if err := c.Quit(); err != nil {
+			t.Fatalf("QUIT failed: %s", err)
+		}
+
+		bcmdbuf.Flush()
+		actualcmds := cmdbuf.String()
+		client := strings.Join(strings.Split(basicClient, "\n"), "\r\n")
+		if client != actualcmds {
+			t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+		}
+	})
+}
+
+func TestNewClient(t *testing.T) {
+	server := strings.Join(strings.Split(newClientServer, "\n"), "\r\n")
+	client := strings.Join(strings.Split(newClientClient, "\n"), "\r\n")
+
+	var cmdbuf bytes.Buffer
+	bcmdbuf := bufio.NewWriter(&cmdbuf)
+	out := func() string {
+		bcmdbuf.Flush()
+		return cmdbuf.String()
+	}
+	var fake faker
+	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
+	c, err := NewClient(fake, "fake.host")
+	if err != nil {
+		t.Fatalf("NewClient: %v\n(after %v)", err, out())
+	}
+	defer c.Close()
+	if ok, args := c.Extension("aUtH"); !ok || args != "LOGIN PLAIN" {
+		t.Fatalf("Expected AUTH supported")
+	}
+	if ok, _ := c.Extension("DSN"); ok {
+		t.Fatalf("Shouldn't support DSN")
+	}
+	if err := c.Quit(); err != nil {
+		t.Fatalf("QUIT failed: %s", err)
+	}
+
+	actualcmds := out()
+	if client != actualcmds {
+		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+	}
+}
+
+var newClientServer = `220 hello world
+250-mx.google.com at your service
+250-SIZE 35651584
+250-AUTH LOGIN PLAIN
+250 8BITMIME
+221 OK
+`
+
+var newClientClient = `EHLO localhost
+QUIT
+`
+
+func TestNewClient2(t *testing.T) {
+	server := strings.Join(strings.Split(newClient2Server, "\n"), "\r\n")
+	client := strings.Join(strings.Split(newClient2Client, "\n"), "\r\n")
+
+	var cmdbuf bytes.Buffer
+	bcmdbuf := bufio.NewWriter(&cmdbuf)
+	var fake faker
+	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
+	c, err := NewClient(fake, "fake.host")
+	if err != nil {
+		t.Fatalf("NewClient: %v", err)
+	}
+	defer c.Close()
+	if ok, _ := c.Extension("DSN"); ok {
+		t.Fatalf("Shouldn't support DSN")
+	}
+	if err := c.Quit(); err != nil {
+		t.Fatalf("QUIT failed: %s", err)
+	}
+
+	bcmdbuf.Flush()
+	actualcmds := cmdbuf.String()
+	if client != actualcmds {
+		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+	}
+}
+
+var newClient2Server = `220 hello world
+502 EH?
+250-mx.google.com at your service
+250-SIZE 35651584
+250-AUTH LOGIN PLAIN
+250 8BITMIME
+221 OK
+`
+
+var newClient2Client = `EHLO localhost
+HELO localhost
+QUIT
+`
+
+func TestNewClientWithTLS(t *testing.T) {
+	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
+	if err != nil {
+		t.Fatalf("loadcert: %v", err)
+	}
+
+	config := tls.Config{Certificates: []tls.Certificate{cert}}
+
+	ln, err := tls.Listen("tcp", "127.0.0.1:0", &config)
+	if err != nil {
+		ln, err = tls.Listen("tcp", "[::1]:0", &config)
+		if err != nil {
+			t.Fatalf("server: listen: %v", err)
+		}
+	}
+
+	go func() {
+		conn, err := ln.Accept()
+		if err != nil {
+			t.Errorf("server: accept: %v", err)
+			return
+		}
+		defer conn.Close()
+
+		_, err = conn.Write([]byte("220 SIGNS\r\n"))
+		if err != nil {
+			t.Errorf("server: write: %v", err)
+			return
+		}
+	}()
+
+	config.InsecureSkipVerify = true
+	conn, err := tls.Dial("tcp", ln.Addr().String(), &config)
+	if err != nil {
+		t.Fatalf("client: dial: %v", err)
+	}
+	defer conn.Close()
+
+	client, err := NewClient(conn, ln.Addr().String())
+	if err != nil {
+		t.Fatalf("smtp: newclient: %v", err)
+	}
+	if !client.tls {
+		t.Errorf("client.tls Got: %t Expected: %t", client.tls, true)
+	}
+}
+
+func TestHello(t *testing.T) {
+
+	if len(helloServer) != len(helloClient) {
+		t.Fatalf("Hello server and client size mismatch")
+	}
+
+	for i := 0; i < len(helloServer); i++ {
+		server := strings.Join(strings.Split(baseHelloServer+helloServer[i], "\n"), "\r\n")
+		client := strings.Join(strings.Split(baseHelloClient+helloClient[i], "\n"), "\r\n")
+		var cmdbuf bytes.Buffer
+		bcmdbuf := bufio.NewWriter(&cmdbuf)
+		var fake faker
+		fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
+		c, err := NewClient(fake, "fake.host")
+		if err != nil {
+			t.Fatalf("NewClient: %v", err)
+		}
+		defer c.Close()
+		c.localName = "customhost"
+		err = nil
+
+		switch i {
+		case 0:
+			err = c.Hello("hostinjection>\n\rDATA\r\nInjected message body\r\n.\r\nQUIT\r\n")
+			if err == nil {
+				t.Errorf("Expected Hello to be rejected due to a message injection attempt")
+			}
+			err = c.Hello("customhost")
+		case 1:
+			err = c.StartTLS(nil)
+			if err.Error() == "502 Not implemented" {
+				err = nil
+			}
+		case 2:
+			err = c.Verify("test@example.com")
+		case 3:
+			c.tls = true
+			c.serverName = "smtp.google.com"
+			err = c.Auth(PlainAuth("", "user", "pass", "smtp.google.com"))
+		case 4:
+			err = c.Mail("test@example.com")
+		case 5:
+			ok, _ := c.Extension("feature")
+			if ok {
+				t.Errorf("Expected FEATURE not to be supported")
+			}
+		case 6:
+			err = c.Reset()
+		case 7:
+			err = c.Quit()
+		case 8:
+			err = c.Verify("test@example.com")
+			if err != nil {
+				err = c.Hello("customhost")
+				if err != nil {
+					t.Errorf("Want error, got none")
+				}
+			}
+		case 9:
+			err = c.Noop()
+		default:
+			t.Fatalf("Unhandled command")
+		}
+
+		if err != nil {
+			t.Errorf("Command %d failed: %v", i, err)
+		}
+
+		bcmdbuf.Flush()
+		actualcmds := cmdbuf.String()
+		if client != actualcmds {
+			t.Errorf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+		}
+	}
+}
+
+var baseHelloServer = `220 hello world
+502 EH?
+250-mx.google.com at your service
+250 FEATURE
+`
+
+var helloServer = []string{
+	"",
+	"502 Not implemented\n",
+	"250 User is valid\n",
+	"235 Accepted\n",
+	"250 Sender ok\n",
+	"",
+	"250 Reset ok\n",
+	"221 Goodbye\n",
+	"250 Sender ok\n",
+	"250 ok\n",
+}
+
+var baseHelloClient = `EHLO customhost
+HELO customhost
+`
+
+var helloClient = []string{
+	"",
+	"STARTTLS\n",
+	"VRFY test@example.com\n",
+	"AUTH PLAIN AHVzZXIAcGFzcw==\n",
+	"MAIL FROM:<test@example.com>\n",
+	"",
+	"RSET\n",
+	"QUIT\n",
+	"VRFY test@example.com\n",
+	"NOOP\n",
+}
+
+func TestSendMail(t *testing.T) {
+	server := strings.Join(strings.Split(sendMailServer, "\n"), "\r\n")
+	client := strings.Join(strings.Split(sendMailClient, "\n"), "\r\n")
+	var cmdbuf bytes.Buffer
+	bcmdbuf := bufio.NewWriter(&cmdbuf)
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("Unable to create listener: %v", err)
+	}
+	defer l.Close()
+
+	// prevent data race on bcmdbuf
+	var done = make(chan struct{})
+	go func(data []string) {
+
+		defer close(done)
+
+		conn, err := l.Accept()
+		if err != nil {
+			t.Errorf("Accept error: %v", err)
+			return
+		}
+		defer conn.Close()
+
+		tc := textproto.NewConn(conn)
+		for i := 0; i < len(data) && data[i] != ""; i++ {
+			tc.PrintfLine(data[i])
+			for len(data[i]) >= 4 && data[i][3] == '-' {
+				i++
+				tc.PrintfLine(data[i])
+			}
+			if data[i] == "221 Goodbye" {
+				return
+			}
+			read := false
+			for !read || data[i] == "354 Go ahead" {
+				msg, err := tc.ReadLine()
+				bcmdbuf.Write([]byte(msg + "\r\n"))
+				read = true
+				if err != nil {
+					t.Errorf("Read error: %v", err)
+					return
+				}
+				if data[i] == "354 Go ahead" && msg == "." {
+					break
+				}
+			}
+		}
+	}(strings.Split(server, "\r\n"))
+
+	err = SendMail(l.Addr().String(), nil, "test@example.com", []string{"other@example.com>\n\rDATA\r\nInjected message body\r\n.\r\nQUIT\r\n"}, []byte(strings.Replace(`From: test@example.com
+To: other@example.com
+Subject: SendMail test
+
+SendMail is working for me.
+`, "\n", "\r\n", -1)))
+	if err == nil {
+		t.Errorf("Expected SendMail to be rejected due to a message injection attempt")
+	}
+
+	err = SendMail(l.Addr().String(), nil, "test@example.com", []string{"other@example.com"}, []byte(strings.Replace(`From: test@example.com
+To: other@example.com
+Subject: SendMail test
+
+SendMail is working for me.
+`, "\n", "\r\n", -1)))
+
+	if err != nil {
+		t.Errorf("%v", err)
+	}
+
+	<-done
+	bcmdbuf.Flush()
+	actualcmds := cmdbuf.String()
+	if client != actualcmds {
+		t.Errorf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+	}
+}
+
+var sendMailServer = `220 hello world
+502 EH?
+250 mx.google.com at your service
+250 Sender ok
+250 Receiver ok
+354 Go ahead
+250 Data ok
+221 Goodbye
+`
+
+var sendMailClient = `EHLO localhost
+HELO localhost
+MAIL FROM:<test@example.com>
+RCPT TO:<other@example.com>
+DATA
+From: test@example.com
+To: other@example.com
+Subject: SendMail test
+
+SendMail is working for me.
+.
+QUIT
+`
+
+func TestSendMailWithAuth(t *testing.T) {
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("Unable to create listener: %v", err)
+	}
+	defer l.Close()
+
+	errCh := make(chan error)
+	go func() {
+		defer close(errCh)
+		conn, err := l.Accept()
+		if err != nil {
+			errCh <- fmt.Errorf("Accept: %v", err)
+			return
+		}
+		defer conn.Close()
+
+		tc := textproto.NewConn(conn)
+		tc.PrintfLine("220 hello world")
+		msg, err := tc.ReadLine()
+		if err != nil {
+			errCh <- fmt.Errorf("ReadLine error: %v", err)
+			return
+		}
+		const wantMsg = "EHLO localhost"
+		if msg != wantMsg {
+			errCh <- fmt.Errorf("unexpected response %q; want %q", msg, wantMsg)
+			return
+		}
+		err = tc.PrintfLine("250 mx.google.com at your service")
+		if err != nil {
+			errCh <- fmt.Errorf("PrintfLine: %v", err)
+			return
+		}
+	}()
+
+	err = SendMail(l.Addr().String(), PlainAuth("", "user", "pass", "smtp.google.com"), "test@example.com", []string{"other@example.com"}, []byte(strings.Replace(`From: test@example.com
+To: other@example.com
+Subject: SendMail test
+
+SendMail is working for me.
+`, "\n", "\r\n", -1)))
+	if err == nil {
+		t.Error("SendMail: Server doesn't support AUTH, expected to get an error, but got none ")
+	}
+	if err.Error() != "smtp: server doesn't support AUTH" {
+		t.Errorf("Expected: smtp: server doesn't support AUTH, got: %s", err)
+	}
+	err = <-errCh
+	if err != nil {
+		t.Fatalf("server error: %v", err)
+	}
+}
+
+func TestAuthFailed(t *testing.T) {
+	server := strings.Join(strings.Split(authFailedServer, "\n"), "\r\n")
+	client := strings.Join(strings.Split(authFailedClient, "\n"), "\r\n")
+	var cmdbuf bytes.Buffer
+	bcmdbuf := bufio.NewWriter(&cmdbuf)
+	var fake faker
+	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
+	c, err := NewClient(fake, "fake.host")
+	if err != nil {
+		t.Fatalf("NewClient: %v", err)
+	}
+	defer c.Close()
+
+	c.tls = true
+	c.serverName = "smtp.google.com"
+	err = c.Auth(PlainAuth("", "user", "pass", "smtp.google.com"))
+
+	if err == nil {
+		t.Error("Auth: expected error; got none")
+	} else if err.Error() != "535 Invalid credentials\nplease see www.example.com" {
+		t.Errorf("Auth: got error: %v, want: %s", err, "535 Invalid credentials\nplease see www.example.com")
+	}
+
+	bcmdbuf.Flush()
+	actualcmds := cmdbuf.String()
+	if client != actualcmds {
+		t.Errorf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+	}
+}
+
+var authFailedServer = `220 hello world
+250-mx.google.com at your service
+250 AUTH LOGIN PLAIN
+535-Invalid credentials
+535 please see www.example.com
+221 Goodbye
+`
+
+var authFailedClient = `EHLO localhost
+AUTH PLAIN AHVzZXIAcGFzcw==
+*
+QUIT
+`
+
+func TestTLSClient(t *testing.T) {
+	if (runtime.GOOS == "freebsd" && runtime.GOARCH == "amd64") || runtime.GOOS == "js" {
+		testenv.SkipFlaky(t, 19229)
+	}
+	ln := newLocalListener(t)
+	defer ln.Close()
+	errc := make(chan error)
+	go func() {
+		errc <- sendMail(ln.Addr().String())
+	}()
+	conn, err := ln.Accept()
+	if err != nil {
+		t.Fatalf("failed to accept connection: %v", err)
+	}
+	defer conn.Close()
+	if err := serverHandle(conn, t); err != nil {
+		t.Fatalf("failed to handle connection: %v", err)
+	}
+	if err := <-errc; err != nil {
+		t.Fatalf("client error: %v", err)
+	}
+}
+
+func TestTLSConnState(t *testing.T) {
+	ln := newLocalListener(t)
+	defer ln.Close()
+	clientDone := make(chan bool)
+	serverDone := make(chan bool)
+	go func() {
+		defer close(serverDone)
+		c, err := ln.Accept()
+		if err != nil {
+			t.Errorf("Server accept: %v", err)
+			return
+		}
+		defer c.Close()
+		if err := serverHandle(c, t); err != nil {
+			t.Errorf("server error: %v", err)
+		}
+	}()
+	go func() {
+		defer close(clientDone)
+		c, err := Dial(ln.Addr().String())
+		if err != nil {
+			t.Errorf("Client dial: %v", err)
+			return
+		}
+		defer c.Quit()
+		cfg := &tls.Config{ServerName: "example.com"}
+		testHookStartTLS(cfg) // set the RootCAs
+		if err := c.StartTLS(cfg); err != nil {
+			t.Errorf("StartTLS: %v", err)
+			return
+		}
+		cs, ok := c.TLSConnectionState()
+		if !ok {
+			t.Errorf("TLSConnectionState returned ok == false; want true")
+			return
+		}
+		if cs.Version == 0 || !cs.HandshakeComplete {
+			t.Errorf("ConnectionState = %#v; expect non-zero Version and HandshakeComplete", cs)
+		}
+	}()
+	<-clientDone
+	<-serverDone
+}
+
+func newLocalListener(t *testing.T) net.Listener {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		ln, err = net.Listen("tcp6", "[::1]:0")
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	return ln
+}
+
+type smtpSender struct {
+	w io.Writer
+}
+
+func (s smtpSender) send(f string) {
+	s.w.Write([]byte(f + "\r\n"))
+}
+
+// smtp server, finely tailored to deal with our own client only!
+func serverHandle(c net.Conn, t *testing.T) error {
+	send := smtpSender{c}.send
+	send("220 127.0.0.1 ESMTP service ready")
+	s := bufio.NewScanner(c)
+	for s.Scan() {
+		switch s.Text() {
+		case "EHLO localhost":
+			send("250-127.0.0.1 ESMTP offers a warm hug of welcome")
+			send("250-STARTTLS")
+			send("250 Ok")
+		case "STARTTLS":
+			send("220 Go ahead")
+			keypair, err := tls.X509KeyPair(localhostCert, localhostKey)
+			if err != nil {
+				return err
+			}
+			config := &tls.Config{Certificates: []tls.Certificate{keypair}}
+			c = tls.Server(c, config)
+			defer c.Close()
+			return serverHandleTLS(c, t)
+		default:
+			t.Fatalf("unrecognized command: %q", s.Text())
+		}
+	}
+	return s.Err()
+}
+
+func serverHandleTLS(c net.Conn, t *testing.T) error {
+	send := smtpSender{c}.send
+	s := bufio.NewScanner(c)
+	for s.Scan() {
+		switch s.Text() {
+		case "EHLO localhost":
+			send("250 Ok")
+		case "MAIL FROM:<joe1@example.com>":
+			send("250 Ok")
+		case "RCPT TO:<joe2@example.com>":
+			send("250 Ok")
+		case "DATA":
+			send("354 send the mail data, end with .")
+			send("250 Ok")
+		case "Subject: test":
+		case "":
+		case "howdy!":
+		case ".":
+		case "QUIT":
+			send("221 127.0.0.1 Service closing transmission channel")
+			return nil
+		default:
+			t.Fatalf("unrecognized command during TLS: %q", s.Text())
+		}
+	}
+	return s.Err()
+}
+
+func init() {
+	testRootCAs := x509.NewCertPool()
+	testRootCAs.AppendCertsFromPEM(localhostCert)
+	testHookStartTLS = func(config *tls.Config) {
+		config.RootCAs = testRootCAs
+	}
+}
+
+func sendMail(hostPort string) error {
+	from := "joe1@example.com"
+	to := []string{"joe2@example.com"}
+	return SendMail(hostPort, nil, from, to, []byte("Subject: test\n\nhowdy!"))
+}
+
+// localhostCert is a PEM-encoded TLS cert generated from src/crypto/tls:
+// go run generate_cert.go --rsa-bits 1024 --host 127.0.0.1,::1,example.com \
+// 		--ca --start-date "Jan 1 00:00:00 1970" --duration=1000000h
+var localhostCert = []byte(`
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`)
+
+// localhostKey is the private key for localhostCert.
+var localhostKey = []byte(testingKey(`
+-----BEGIN RSA TESTING KEY-----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+-----END RSA TESTING KEY-----`))
+
+func testingKey(s string) string { return strings.ReplaceAll(s, "TESTING KEY", "PRIVATE KEY") }