Clean up some copy-paste code related to SMTP communication

email.go

@@ -504,32 +504,51 @@ func (e *Email) Bytes() ([]byte, error) {
 	return buff.Bytes(), nil
 }
 
-// Send an email using the given host and SMTP auth (optional), returns any error thrown by smtp.SendMail
-// This function merges the To, Cc, and Bcc fields and calls the smtp.SendMail function using the Email.Bytes() output as the message
-func (e *Email) Send(addr string, a smtp.Auth) error {
+type smtpInfo struct {
+	to []string
+	sender string
+	raw []byte
+}
+
+func (e *Email) generateSMTPInfo() (*smtpInfo, error) {
 	// Merge the To, Cc, and Bcc fields
 	to := make([]string, 0, len(e.To)+len(e.Cc)+len(e.Bcc))
 	to = append(append(append(to, e.To...), e.Cc...), e.Bcc...)
 	for i := 0; i < len(to); i++ {
 		addr, err := mail.ParseAddress(to[i])
 		if err != nil {
-			return err
+			return nil, err
 		}
 		to[i] = addr.Address
 	}
 	// Check to make sure there is at least one recipient and one "From" address
 	if e.From == "" || len(to) == 0 {
-		return errors.New("Must specify at least one From address and one To address")
+		return nil, errors.New("Must specify at least one From address and one To address")
 	}
 	sender, err := e.parseSender()
 	if err != nil {
-		return err
+		return nil, err
 	}
 	raw, err := e.Bytes()
+	if err != nil {
+		return nil, err
+	}
+
+	return &smtpInfo{
+		to: to,
+		sender: sender,
+		raw: raw}, err
+}
+
+// Send an email using the given host and SMTP auth (optional), returns any error thrown by smtp.SendMail
+// This function merges the To, Cc, and Bcc fields and calls the smtp.SendMail function using the Email.Bytes() output as the message
+func (e *Email) Send(addr string, a smtp.Auth) error {
+	s, err := e.generateSMTPInfo()
 	if err != nil {
 		return err
 	}
-	return smtp.SendMail(addr, a, sender, to, raw)
+
+	return smtp.SendMail(addr, a, s.sender, s.to, s.raw)
 }
 
 // Select and parse an SMTP envelope sender address.  Choose Email.Sender if set, or fallback to Email.From.
@@ -549,30 +568,36 @@ func (e *Email) parseSender() (string, error) {
 	}
 }
 
-// SendWithTLS sends an email over tls with an optional TLS config.
-//
-// The TLS Config is helpful if you need to connect to a host that is used an untrusted
-// certificate.
-func (e *Email) SendWithTLS(addr string, a smtp.Auth, t *tls.Config) error {
-	// Merge the To, Cc, and Bcc fields
-	to := make([]string, 0, len(e.To)+len(e.Cc)+len(e.Bcc))
-	to = append(append(append(to, e.To...), e.Cc...), e.Bcc...)
-	for i := 0; i < len(to); i++ {
-		addr, err := mail.ParseAddress(to[i])
-		if err != nil {
+func (e *Email) sendHelper(c *smtp.Client, s *smtpInfo) error {
+	if err := c.Mail(s.sender); err != nil {
+		return err
+	}
+	for _, addr := range s.to {
+		if err := c.Rcpt(addr); err != nil {
 			return err
 		}
-		to[i] = addr.Address
 	}
-	// Check to make sure there is at least one recipient and one "From" address
-	if e.From == "" || len(to) == 0 {
-		return errors.New("Must specify at least one From address and one To address")
+	w, err := c.Data()
+	if err != nil {
+		return err
 	}
-	sender, err := e.parseSender()
+	_, err = w.Write(s.raw)
 	if err != nil {
 		return err
 	}
-	raw, err := e.Bytes()
+	err = w.Close()
+	if err != nil {
+		return err
+	}
+	return c.Quit()
+}
+
+// SendWithTLS sends an email over tls with an optional TLS config.
+//
+// The TLS Config is helpful if you need to connect to a host that is used an untrusted
+// certificate.
+func (e *Email) SendWithTLS(addr string, a smtp.Auth, t *tls.Config) error {
+	s, err := e.generateSMTPInfo()
 	if err != nil {
 		return err
 	}
@@ -598,53 +623,16 @@ func (e *Email) SendWithTLS(addr string, a smtp.Auth, t *tls.Config) error {
 			}
 		}
 	}
-	if err = c.Mail(sender); err != nil {
-		return err
-	}
-	for _, addr := range to {
-		if err = c.Rcpt(addr); err != nil {
-			return err
-		}
-	}
-	w, err := c.Data()
-	if err != nil {
-		return err
-	}
-	_, err = w.Write(raw)
-	if err != nil {
-		return err
-	}
-	err = w.Close()
-	if err != nil {
-		return err
-	}
-	return c.Quit()
+
+	return e.sendHelper(c, s)
 }
 
 // SendWithStartTLS sends an email over TLS using STARTTLS with an optional TLS config.
 //
 // The TLS Config is helpful if you need to connect to a host that is used an untrusted
 // certificate.
 func (e *Email) SendWithStartTLS(addr string, a smtp.Auth, t *tls.Config) error {
-	// Merge the To, Cc, and Bcc fields
-	to := make([]string, 0, len(e.To)+len(e.Cc)+len(e.Bcc))
-	to = append(append(append(to, e.To...), e.Cc...), e.Bcc...)
-	for i := 0; i < len(to); i++ {
-		addr, err := mail.ParseAddress(to[i])
-		if err != nil {
-			return err
-		}
-		to[i] = addr.Address
-	}
-	// Check to make sure there is at least one recipient and one "From" address
-	if e.From == "" || len(to) == 0 {
-		return errors.New("Must specify at least one From address and one To address")
-	}
-	sender, err := e.parseSender()
-	if err != nil {
-		return err
-	}
-	raw, err := e.Bytes()
+	s, err := e.generateSMTPInfo()
 	if err != nil {
 		return err
 	}
@@ -673,27 +661,7 @@ func (e *Email) SendWithStartTLS(addr string, a smtp.Auth, t *tls.Config) error
 			}
 		}
 	}
-	if err = c.Mail(sender); err != nil {
-		return err
-	}
-	for _, addr := range to {
-		if err = c.Rcpt(addr); err != nil {
-			return err
-		}
-	}
-	w, err := c.Data()
-	if err != nil {
-		return err
-	}
-	_, err = w.Write(raw)
-	if err != nil {
-		return err
-	}
-	err = w.Close()
-	if err != nil {
-		return err
-	}
-	return c.Quit()
+	return e.sendHelper(c, s)
 }
 
 // Attachment is a struct representing an email attachment.

go.mod

@@ -0,0 +1,3 @@
+module github.com/jordan-wright/email
+
+go 1.15

pool.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"io"
 	"net"
-	"net/mail"
 	"net/smtp"
 	"net/textproto"
 	"sync"
@@ -285,75 +284,18 @@ func (p *Pool) Send(e *Email, timeout time.Duration) (err error) {
 		return p.failedToGet(start)
 	}
 
-	defer func() {
-		p.maybeReplace(err, c)
-	}()
-
-	recipients, err := addressLists(e.To, e.Cc, e.Bcc)
-	if err != nil {
-		return
-	}
-
-	msg, err := e.Bytes()
-	if err != nil {
-		return
-	}
-
-	from, err := emailOnly(e.From)
-	if err != nil {
-		return
-	}
-	if err = c.Mail(from); err != nil {
-		return
-	}
-
-	for _, recip := range recipients {
-		if err = c.Rcpt(recip); err != nil {
-			return
-		}
-	}
-
-	w, err := c.Data()
+	var s *smtpInfo
+	s, err = e.generateSMTPInfo()
 	if err != nil {
-		return
-	}
-	if _, err = w.Write(msg); err != nil {
-		return
+		return err
 	}
 
-	err = w.Close()
+	err = e.sendHelper(c.Client, s)
+	p.maybeReplace(err, c)
 
 	return
 }
 
-func emailOnly(full string) (string, error) {
-	addr, err := mail.ParseAddress(full)
-	if err != nil {
-		return "", err
-	}
-	return addr.Address, nil
-}
-
-func addressLists(lists ...[]string) ([]string, error) {
-	length := 0
-	for _, lst := range lists {
-		length += len(lst)
-	}
-	combined := make([]string, 0, length)
-
-	for _, lst := range lists {
-		for _, full := range lst {
-			addr, err := emailOnly(full)
-			if err != nil {
-				return nil, err
-			}
-			combined = append(combined, addr)
-		}
-	}
-
-	return combined, nil
-}
-
 // Close immediately changes the pool's state so no new connections will be
 // created, then gets and closes the existing ones as they become available.
 func (p *Pool) Close() {