send: move code to lib for reuse

Move the code which handles the preparation of a sender into which the
message can be written into lib to allow for reuse. Also hide the
sending backend a bit more from the `:send` command code by introducing
a NewSender function which determines which backend should be used and
invokes the appropriate sender factory function.

Rename send() to sendHelper() to avoid collision.

Signed-off-by: Karel Balej <balejk@matfyz.cz>
Acked-by: Robin Jarry <robin@jarry.cc>

6 files changed, 375 insertions, 0 deletions

diff --git a/lib/send/jmap.go b/lib/send/jmap.go
new file mode 100644
index 00000000..9682629e
--- /dev/null
+++ b/lib/send/jmap.go
@@ -0,0 +1,40 @@
+package send
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/emersion/go-message/mail"
+
+	"git.sr.ht/~rjarry/aerc/worker/types"
+)
+
+func newJmapSender(
+	worker *types.Worker, from *mail.Address, rcpts []*mail.Address,
+) (io.WriteCloser, error) {
+	var writer io.WriteCloser
+	done := make(chan error)
+
+	worker.PostAction(
+		&types.StartSendingMessage{From: from, Rcpts: rcpts},
+		func(msg types.WorkerMessage) {
+			switch msg := msg.(type) {
+			case *types.Done:
+				return
+			case *types.Unsupported:
+				done <- fmt.Errorf("unsupported by worker")
+			case *types.Error:
+				done <- msg.Error
+			case *types.MessageWriter:
+				writer = msg.Writer
+			default:
+				done <- fmt.Errorf("unexpected worker message: %#v", msg)
+			}
+			close(done)
+		},
+	)
+
+	err := <-done
+
+	return writer, err
+}
diff --git a/lib/send/parse.go b/lib/send/parse.go
new file mode 100644
index 00000000..460e91dc
--- /dev/null
+++ b/lib/send/parse.go
@@ -0,0 +1,32 @@
+package send
+
+import (
+	"fmt"
+	"net/url"
+	"strings"
+)
+
+func parseScheme(uri *url.URL) (protocol string, auth string, err error) {
+	protocol = ""
+	auth = "plain"
+	if uri.Scheme != "" {
+		parts := strings.Split(uri.Scheme, "+")
+		switch len(parts) {
+		case 1:
+			protocol = parts[0]
+		case 2:
+			if parts[1] == "insecure" {
+				protocol = uri.Scheme
+			} else {
+				protocol = parts[0]
+				auth = parts[1]
+			}
+		case 3:
+			protocol = parts[0] + "+" + parts[1]
+			auth = parts[2]
+		default:
+			return "", "", fmt.Errorf("Unknown scheme %s", uri.Scheme)
+		}
+	}
+	return protocol, auth, nil
+}
diff --git a/lib/send/sasl.go b/lib/send/sasl.go
new file mode 100644
index 00000000..01e006e3
--- /dev/null
+++ b/lib/send/sasl.go
@@ -0,0 +1,77 @@
+package send
+
+import (
+	"fmt"
+	"net/url"
+
+	"github.com/emersion/go-sasl"
+	"golang.org/x/oauth2"
+
+	"git.sr.ht/~rjarry/aerc/lib"
+)
+
+func newSaslClient(auth string, uri *url.URL) (sasl.Client, error) {
+	var saslClient sasl.Client
+	switch auth {
+	case "":
+		fallthrough
+	case "none":
+		saslClient = nil
+	case "login":
+		password, _ := uri.User.Password()
+		saslClient = sasl.NewLoginClient(uri.User.Username(), password)
+	case "plain":
+		password, _ := uri.User.Password()
+		saslClient = sasl.NewPlainClient("", uri.User.Username(), password)
+	case "oauthbearer":
+		q := uri.Query()
+		oauth2 := &oauth2.Config{}
+		if q.Get("token_endpoint") != "" {
+			oauth2.ClientID = q.Get("client_id")
+			oauth2.ClientSecret = q.Get("client_secret")
+			oauth2.Scopes = []string{q.Get("scope")}
+			oauth2.Endpoint.TokenURL = q.Get("token_endpoint")
+		}
+		password, _ := uri.User.Password()
+		bearer := lib.OAuthBearer{
+			OAuth2:  oauth2,
+			Enabled: true,
+		}
+		if bearer.OAuth2.Endpoint.TokenURL != "" {
+			token, err := bearer.ExchangeRefreshToken(password)
+			if err != nil {
+				return nil, err
+			}
+			password = token.AccessToken
+		}
+		saslClient = sasl.NewOAuthBearerClient(&sasl.OAuthBearerOptions{
+			Username: uri.User.Username(),
+			Token:    password,
+		})
+	case "xoauth2":
+		q := uri.Query()
+		oauth2 := &oauth2.Config{}
+		if q.Get("token_endpoint") != "" {
+			oauth2.ClientID = q.Get("client_id")
+			oauth2.ClientSecret = q.Get("client_secret")
+			oauth2.Scopes = []string{q.Get("scope")}
+			oauth2.Endpoint.TokenURL = q.Get("token_endpoint")
+		}
+		password, _ := uri.User.Password()
+		bearer := lib.Xoauth2{
+			OAuth2:  oauth2,
+			Enabled: true,
+		}
+		if bearer.OAuth2.Endpoint.TokenURL != "" {
+			token, err := bearer.ExchangeRefreshToken(password)
+			if err != nil {
+				return nil, err
+			}
+			password = token.AccessToken
+		}
+		saslClient = lib.NewXoauth2Client(uri.User.Username(), password)
+	default:
+		return nil, fmt.Errorf("Unsupported auth mechanism %s", auth)
+	}
+	return saslClient, nil
+}
diff --git a/lib/send/sender.go b/lib/send/sender.go
new file mode 100644
index 00000000..a1e03da5
--- /dev/null
+++ b/lib/send/sender.go
@@ -0,0 +1,35 @@
+package send
+
+import (
+	"fmt"
+	"io"
+	"net/url"
+
+	"github.com/emersion/go-message/mail"
+
+	"git.sr.ht/~rjarry/aerc/worker/types"
+)
+
+// NewSender returns an io.WriterCloser into which the caller can write
+// contents of a message. The caller must invoke the Close() method on the
+// sender when finished.
+func NewSender(
+	worker *types.Worker, uri *url.URL, domain string,
+	from *mail.Address, rcpts []*mail.Address,
+) (io.WriteCloser, error) {
+	protocol, auth, err := parseScheme(uri)
+	if err != nil {
+		return nil, err
+	}
+
+	switch protocol {
+	case "smtp", "smtp+insecure", "smtps":
+		return newSmtpSender(protocol, auth, uri, domain, from, rcpts)
+	case "jmap":
+		return newJmapSender(worker, from, rcpts)
+	case "":
+		return newSendmailSender(uri, rcpts)
+	default:
+		return nil, fmt.Errorf("unsupported protocol %s", protocol)
+	}
+}
diff --git a/lib/send/sendmail.go b/lib/send/sendmail.go
new file mode 100644
index 00000000..b267721e
--- /dev/null
+++ b/lib/send/sendmail.go
@@ -0,0 +1,55 @@
+package send
+
+import (
+	"fmt"
+	"io"
+	"net/url"
+	"os/exec"
+
+	"git.sr.ht/~rjarry/go-opt"
+	"github.com/emersion/go-message/mail"
+	"github.com/pkg/errors"
+)
+
+type sendmailSender struct {
+	cmd   *exec.Cmd
+	stdin io.WriteCloser
+}
+
+func (s *sendmailSender) Write(p []byte) (int, error) {
+	return s.stdin.Write(p)
+}
+
+func (s *sendmailSender) Close() error {
+	se := s.stdin.Close()
+	ce := s.cmd.Wait()
+	if se != nil {
+		return se
+	}
+	return ce
+}
+
+func newSendmailSender(uri *url.URL, rcpts []*mail.Address) (io.WriteCloser, error) {
+	args := opt.SplitArgs(uri.Path)
+	if len(args) == 0 {
+		return nil, fmt.Errorf("no command specified")
+	}
+	bin := args[0]
+	rs := make([]string, len(rcpts))
+	for i := range rcpts {
+		rs[i] = rcpts[i].Address
+	}
+	args = append(args[1:], rs...)
+	cmd := exec.Command(bin, args...)
+	s := &sendmailSender{cmd: cmd}
+	var err error
+	s.stdin, err = s.cmd.StdinPipe()
+	if err != nil {
+		return nil, errors.Wrap(err, "cmd.StdinPipe")
+	}
+	err = s.cmd.Start()
+	if err != nil {
+		return nil, errors.Wrap(err, "cmd.Start")
+	}
+	return s, nil
+}
diff --git a/lib/send/smtp.go b/lib/send/smtp.go
new file mode 100644
index 00000000..2cc53d25
--- /dev/null
+++ b/lib/send/smtp.go
@@ -0,0 +1,136 @@
+package send
+
+import (
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net/url"
+	"strings"
+
+	"github.com/emersion/go-message/mail"
+	"github.com/emersion/go-smtp"
+	"github.com/pkg/errors"
+)
+
+func connectSmtp(starttls bool, host string, domain string) (*smtp.Client, error) {
+	serverName := host
+	if !strings.ContainsRune(host, ':') {
+		host += ":587" // Default to submission port
+	} else {
+		serverName = host[:strings.IndexRune(host, ':')]
+	}
+	conn, err := smtp.Dial(host)
+	if err != nil {
+		return nil, errors.Wrap(err, "smtp.Dial")
+	}
+	if domain != "" {
+		err := conn.Hello(domain)
+		if err != nil {
+			return nil, errors.Wrap(err, "Hello")
+		}
+	}
+	if starttls {
+		if sup, _ := conn.Extension("STARTTLS"); !sup {
+			err := errors.New("STARTTLS requested, but not supported " +
+				"by this SMTP server. Is someone tampering with your " +
+				"connection?")
+			conn.Close()
+			return nil, err
+		}
+		if err = conn.StartTLS(&tls.Config{
+			ServerName: serverName,
+		}); err != nil {
+			conn.Close()
+			return nil, errors.Wrap(err, "StartTLS")
+		}
+	}
+
+	return conn, nil
+}
+
+func connectSmtps(host string) (*smtp.Client, error) {
+	serverName := host
+	if !strings.ContainsRune(host, ':') {
+		host += ":465" // Default to smtps port
+	} else {
+		serverName = host[:strings.IndexRune(host, ':')]
+	}
+	conn, err := smtp.DialTLS(host, &tls.Config{
+		ServerName: serverName,
+	})
+	if err != nil {
+		return nil, errors.Wrap(err, "smtp.DialTLS")
+	}
+	return conn, nil
+}
+
+type smtpSender struct {
+	conn *smtp.Client
+	w    io.WriteCloser
+}
+
+func (s *smtpSender) Write(p []byte) (int, error) {
+	return s.w.Write(p)
+}
+
+func (s *smtpSender) Close() error {
+	we := s.w.Close()
+	ce := s.conn.Close()
+	if we != nil {
+		return we
+	}
+	return ce
+}
+
+func newSmtpSender(
+	protocol string, auth string, uri *url.URL, domain string,
+	from *mail.Address, rcpts []*mail.Address,
+) (io.WriteCloser, error) {
+	var err error
+	var conn *smtp.Client
+	switch protocol {
+	case "smtp":
+		conn, err = connectSmtp(true, uri.Host, domain)
+	case "smtp+insecure":
+		conn, err = connectSmtp(false, uri.Host, domain)
+	case "smtps":
+		conn, err = connectSmtps(uri.Host)
+	default:
+		return nil, fmt.Errorf("not a smtp protocol %s", protocol)
+	}
+
+	if err != nil {
+		return nil, errors.Wrap(err, "Connection failed")
+	}
+
+	saslclient, err := newSaslClient(auth, uri)
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+	if saslclient != nil {
+		if err := conn.Auth(saslclient); err != nil {
+			conn.Close()
+			return nil, errors.Wrap(err, "conn.Auth")
+		}
+	}
+	s := &smtpSender{
+		conn: conn,
+	}
+	if err := s.conn.Mail(from.Address, nil); err != nil {
+		conn.Close()
+		return nil, errors.Wrap(err, "conn.Mail")
+	}
+	for _, rcpt := range rcpts {
+		if err := s.conn.Rcpt(rcpt.Address); err != nil {
+			conn.Close()
+			return nil, errors.Wrap(err, "conn.Rcpt")
+		}
+	}
+	s.w, err = s.conn.Data()
+	if err != nil {
+		conn.Close()
+		return nil, errors.Wrap(err, "conn.Data")
+	}
+	return s.w, nil
+}