forked from joegrasse/mail
/
mail.go
884 lines (734 loc) · 21.7 KB
/
mail.go
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package mail
import (
"bytes"
"crypto/tls"
"encoding/base64"
"errors"
"fmt"
"github.com/joegrasse/mime/header"
"io"
"io/ioutil"
"mime"
"mime/multipart"
"mime/quotedprintable"
"net"
"net/mail"
"net/smtp"
"net/textproto"
"path/filepath"
"regexp"
"strconv"
"strings"
"time"
)
// email represents an email message.
type email struct {
from string
sender string
replyTo string
returnPath string
recipients []string
headers textproto.MIMEHeader
parts []part
attachments []*file
inlines []*file
Charset string
Encoding encoding
Encryption encryption
Username string
Password string
TLSConfig *tls.Config
ConnectTimeout int
}
// part represents the different content parts of an email body.
type part struct {
contentType string
body *bytes.Buffer
}
// file represents the files that can be added to the email message.
type file struct {
filename string
mimeType string
data []byte
}
type encryption int
const (
EncryptionTLS encryption = iota
EncryptionSSL
EncryptionNone
)
var encryptionTypes = [...]string{"TLS", "SSL", "None"}
func (encryption encryption) String() string {
return encryptionTypes[encryption]
}
type encoding int
const (
EncodingQuotedPrintable encoding = iota
EncodingBase64
EncodingNone
)
var encodingTypes = [...]string{"quoted-printable", "base64", "binary"}
func (encoding encoding) String() string {
return encodingTypes[encoding]
}
// New creates a new email. It uses UTF-8 by default.
func New() *email {
email := &email{
headers: make(textproto.MIMEHeader),
Charset: "UTF-8",
Encoding: EncodingQuotedPrintable,
Encryption: EncryptionNone,
TLSConfig: new(tls.Config),
}
email.AddHeader("MIME-Version", "1.0")
return email
}
// SetFrom sets the From address.
func (email *email) SetFrom(address string) error {
return email.AddAddresses("From", address)
}
// SetSender sets the Sender address.
func (email *email) SetSender(address string) error {
return email.AddAddresses("Sender", address)
}
// SetReplyTo sets the Reply-To address.
func (email *email) SetReplyTo(address string) error {
return email.AddAddresses("Reply-To", address)
}
// SetReturnPath sets the Return-Path address. This is most often used
// to send bounced emails to a different email address.
func (email *email) SetReturnPath(address string) error {
return email.AddAddresses("Return-Path", address)
}
// AddTo adds a To address. You can provide multiple
// addresses at the same time.
func (email *email) AddTo(addresses ...string) error {
return email.AddAddresses("To", addresses...)
}
// AddCc adds a Cc address. You can provide multiple
// addresses at the same time.
func (email *email) AddCc(addresses ...string) error {
return email.AddAddresses("Cc", addresses...)
}
// AddBcc adds a Bcc address. You can provide multiple
// addresses at the same time.
func (email *email) AddBcc(addresses ...string) error {
return email.AddAddresses("Bcc", addresses...)
}
// AddAddresses allows you to add addresses to the specified address header.
func (email *email) AddAddresses(header string, addresses ...string) error {
found := false
// check for a valid address header
for _, h := range []string{"To", "Cc", "Bcc", "From", "Sender", "Reply-To", "Return-Path"} {
if header == h {
found = true
}
}
if !found {
return errors.New("Mail Error: Invalid address header; Header: [" + header + "]")
}
// check to see if the addresses are valid
for i := range addresses {
address, err := mail.ParseAddress(addresses[i])
if err != nil {
return errors.New("Mail Error: " + err.Error() + "; Header: [" + header + "] Address: [" + addresses[i] + "]")
}
// check for more than one address
switch {
case header == "From" && len(email.from) > 0:
fallthrough
case header == "Sender" && len(email.sender) > 0:
fallthrough
case header == "Reply-To" && len(email.replyTo) > 0:
fallthrough
case header == "Return-Path" && len(email.returnPath) > 0:
return errors.New("Mail Error: There can only be one \"" + header + "\" address; Header: [" + header + "] Address: [" + addresses[i] + "]")
default:
// other address types can have more than one address
}
// save the address
switch header {
case "From":
email.from = address.Address
case "Sender":
email.sender = address.Address
case "Reply-To":
email.replyTo = address.Address
case "Return-Path":
email.returnPath = address.Address
default:
// check that the address was added to the recipients list
email.recipients, err = addAddress(email.recipients, address.Address)
if err != nil {
return errors.New("Mail Error: " + err.Error() + "; Header: [" + header + "] Address: [" + addresses[i] + "]")
}
}
// make sure the from and sender addresses are different
if email.from != "" && email.sender != "" && email.from == email.sender {
email.sender = ""
email.headers.Del("Sender")
return errors.New("Mail Error: From and Sender should not be set to the same address.")
}
// add all addresses to the headers except for Bcc and Return-Path
if header != "Bcc" && header != "Return-Path" {
// add the address to the headers
email.headers.Add(header, address.String())
}
}
return nil
}
// addAddress adds an address to the address list if it hasn't already been added
func addAddress(addressList []string, address string) ([]string, error) {
// loop through the address list to check for dups
for _, a := range addressList {
if address == a {
return addressList, errors.New("Mail Error: Address: [" + address + "] has already been added")
}
}
return append(addressList, address), nil
}
type priority int
const (
PriorityHigh priority = iota
PriorityLow
)
var priorities = [...]string{"High", "Low"}
func (priority priority) String() string {
return priorities[priority]
}
// SetPriority sets the email message priority. Use with
// either "High" or "Low".
func (email *email) SetPriority(priority priority) error {
switch priority {
case PriorityHigh:
return email.AddHeaders(textproto.MIMEHeader{
"X-Priority": {"1 (Highest)"},
"X-MSMail-Priority": {"High"},
"Importance": {"High"},
})
case PriorityLow:
return email.AddHeaders(textproto.MIMEHeader{
"X-Priority": {"5 (Lowest)"},
"X-MSMail-Priority": {"Low"},
"Importance": {"Low"},
})
default:
}
return nil
}
// SetDate sets the date header to the provided date/time.
// The format of the string should be YYYY-MM-DD HH:MM:SS Time Zone.
//
// Example: SetDate("2015-04-28 10:32:00 CDT")
func (email *email) SetDate(dateTime string) error {
const dateFormat = "2006-01-02 15:04:05 MST"
// Try to parse the provided date/time
dt, err := time.Parse(dateFormat, dateTime)
if err != nil {
return errors.New("Mail Error: Setting date failed with: " + err.Error())
}
email.headers.Set("Date", dt.Format(time.RFC1123Z))
return nil
}
// SetSubject sets the subject of the email message.
func (email *email) SetSubject(subject string) error {
return email.AddHeader("Subject", subject)
}
// SetBody sets the body of the email message.
func (email *email) SetBody(contentType, body string) {
email.parts = []part{
part{
contentType: contentType,
body: bytes.NewBufferString(body),
},
}
}
// Header adds the given "header" with the passed "value".
func (email *email) AddHeader(header string, values ...string) error {
// check that there is actually a value
if len(values) < 1 {
return errors.New("Mail Error: no value provided; Header: [" + header + "]")
}
switch header {
case "Sender":
fallthrough
case "From":
fallthrough
case "To":
fallthrough
case "Bcc":
fallthrough
case "Cc":
fallthrough
case "Reply-To":
fallthrough
case "Return-Path":
return email.AddAddresses(header, values...)
case "Date":
if len(values) > 1 {
return errors.New("Mail Error: To many dates provided")
}
return email.SetDate(values[0])
default:
email.headers[header] = values
}
return nil
}
// Headers is used to add mulitple headers at once
func (email *email) AddHeaders(headers textproto.MIMEHeader) error {
for header, values := range headers {
if err := email.AddHeader(header, values...); err != nil {
return err
}
}
return nil
}
// Alternative allows you to add alternative parts to the body
// of the email message. This is most commonly used to add an
// html version in addition to a plain text version that was
// already added with SetBody.
func (email *email) AddAlternative(contentType, body string) {
email.parts = append(email.parts,
part{
contentType: contentType,
body: bytes.NewBufferString(body),
},
)
}
// Attach allows you to add an attachment to the email message.
// You can optionally provide a different name for the file.
func (email *email) AddAttachment(file string, name ...string) error {
if len(name) > 1 {
return errors.New("Mail Error: Attach can only have a file and an optional name")
}
return email.attach(file, false, name...)
}
// Inline allows you to add an inline attachment to the email message.
// You can optionally provide a different name for the file.
func (email *email) AddInline(file string, name ...string) error {
if len(name) > 1 {
return errors.New("Mail Error: Inline can only have a file and an optional name")
}
return email.attach(file, true, name...)
}
// attach does the low level attaching of the files
func (email *email) attach(f string, inline bool, name ...string) error {
// Get the file data
data, err := ioutil.ReadFile(f)
if err != nil {
return errors.New("Mail Error: Failed to add file with following error: " + err.Error())
}
// get the file mime type
mimeType := mime.TypeByExtension(filepath.Ext(f))
if mimeType == "" {
mimeType = "application/octet-stream"
}
// get the filename
_, filename := filepath.Split(f)
// if an alternative filename was provided, use that instead
if len(name) == 1 {
filename = name[0]
}
if inline {
email.inlines = append(email.inlines, &file{
filename: filename,
mimeType: mimeType,
data: data,
})
} else {
email.attachments = append(email.attachments, &file{
filename: filename,
mimeType: mimeType,
data: data,
})
}
return nil
}
// getFrom returns the sender of the email, if any
func (email *email) getFrom() string {
from := email.returnPath
if from == "" {
from = email.sender
if from == "" {
from = email.from
if from == "" {
from = email.replyTo
}
}
}
return from
}
func (email *email) hasMixedPart() bool {
return (len(email.parts) > 0 && len(email.attachments) > 0) || len(email.attachments) > 1
}
func (email *email) hasRelatedPart() bool {
return (len(email.parts) > 0 && len(email.inlines) > 0) || len(email.inlines) > 1
}
func (email *email) hasAlternativePart() bool {
return len(email.parts) > 1
}
// GetMessage builds and returns the email message
func (email *email) GetMessage() string {
msg := newMessage(email)
if email.hasMixedPart() {
msg.openMultipart("mixed")
}
if email.hasRelatedPart() {
msg.openMultipart("related")
}
if email.hasAlternativePart() {
msg.openMultipart("alternative")
}
for _, part := range email.parts {
msg.addBody(part.contentType, part.body.Bytes())
}
if email.hasAlternativePart() {
msg.closeMultipart()
}
msg.addFiles(email.inlines, true)
if email.hasRelatedPart() {
msg.closeMultipart()
}
msg.addFiles(email.attachments, false)
if email.hasMixedPart() {
msg.closeMultipart()
}
return msg.getHeaders() + msg.body.String()
}
// Send sends the composed email
func (email *email) Send(address string) error {
var auth smtp.Auth
from := email.getFrom()
if from == "" {
return errors.New(`Mail Error: No "From" address specified.`)
}
if len(email.recipients) < 1 {
return errors.New("Mail Error: No recipient specified.")
}
msg := email.GetMessage()
host, port, err := net.SplitHostPort(address)
if err != nil {
return errors.New("Mail Error: " + err.Error())
}
if email.Username != "" || email.Password != "" {
auth = smtp.PlainAuth("", email.Username, email.Password, host)
}
return send(host, port, from, email.recipients, msg, auth, email.Encryption, email.TLSConfig, email.ConnectTimeout)
}
// dial connects to the smtp server with the request encryption type
func dial(host string, port string, encryption encryption, config *tls.Config) (*smtp.Client, error) {
var conn net.Conn
var err error
address := host + ":" + port
// do the actual dial
switch encryption {
case EncryptionSSL:
conn, err = tls.Dial("tcp", address, config)
default:
conn, err = net.Dial("tcp", address)
}
if err != nil {
return nil, errors.New("Mail Error on dailing with encryption type " + encryption.String() + ": " + err.Error())
}
c, err := smtp.NewClient(conn, host)
if err != nil {
return nil, errors.New("Mail Error on smtp dial: " + err.Error())
}
return c, err
}
// smtpConnect connects to the smtp server and starts TLS and passes auth
// if necessary
func smtpConnect(host string, port string, from string, to []string, msg string, auth smtp.Auth, encryption encryption, config *tls.Config) (*smtp.Client, error) {
// connect to the mail server
c, err := dial(host, port, encryption, config)
if err != nil {
return nil, err
}
// send Hello
if err = c.Hello("localhost"); err != nil {
c.Close()
return nil, errors.New("Mail Error on Hello: " + err.Error())
}
// start TLS if necessary
if encryption == EncryptionTLS {
if ok, _ := c.Extension("STARTTLS"); ok {
if config.ServerName == "" {
config = &tls.Config{ServerName: host}
}
if err = c.StartTLS(config); err != nil {
c.Close()
return nil, errors.New("Mail Error on Start TLS: " + err.Error())
}
}
}
// pass the authentication if necessary
if auth != nil {
if ok, _ := c.Extension("AUTH"); ok {
if err = c.Auth(auth); err != nil {
c.Close()
return nil, errors.New("Mail Error on Auth: " + err.Error())
}
}
}
return c, nil
}
type smtpConnectErrorChannel struct {
client *smtp.Client
err error
}
// send does the low level sending of the email
func send(host string, port string, from string, to []string, msg string, auth smtp.Auth, encryption encryption, config *tls.Config, connectTimeout int) error {
var smtpConnectChannel chan smtpConnectErrorChannel
var c *smtp.Client = nil
var err error
// set the timeout value
timeout := time.Duration(connectTimeout) * time.Second
// if there is a timeout, setup the channel and do the connect under a goroutine
if timeout != 0 {
smtpConnectChannel = make(chan smtpConnectErrorChannel, 2)
go func() {
c, err = smtpConnect(host, port, from, to, msg, auth, encryption, config)
// send the result
smtpConnectChannel <- smtpConnectErrorChannel{
client: c,
err: err,
}
}()
}
if timeout == 0 {
// no timeout, just fire the connect
c, err = smtpConnect(host, port, from, to, msg, auth, encryption, config)
} else {
// get the connect result or timeout result, which ever happens first
select {
case result := <-smtpConnectChannel:
c = result.client
err = result.err
case <-time.After(timeout):
return errors.New("Mail Error: SMTP Connection timed out")
}
}
// check for connect error
if err != nil {
return err
}
defer c.Close()
// Set the sender
if err := c.Mail(from); err != nil {
return err
}
// Set the recipients
for _, address := range to {
if err := c.Rcpt(address); err != nil {
return err
}
}
// Send the data command
w, err := c.Data()
if err != nil {
return err
}
// write the message
_, err = fmt.Fprint(w, msg)
if err != nil {
return err
}
err = w.Close()
if err != nil {
return err
}
return c.Quit()
}
type message struct {
headers textproto.MIMEHeader
body *bytes.Buffer
writers []*multipart.Writer
parts uint8
cids map[string]string
charset string
encoding encoding
}
func newMessage(email *email) *message {
return &message{
headers: email.headers,
body: new(bytes.Buffer),
cids: make(map[string]string),
charset: email.Charset,
encoding: email.Encoding}
}
func encodeHeader(text string, charset string, usedChars int) string {
// create buffer
buf := new(bytes.Buffer)
// encode
encoder := header.NewEncoder(buf, charset, usedChars)
encoder.Encode([]byte(text))
return buf.String()
/*
switch encoding {
case EncodingBase64:
return mime.BEncoding.Encode(charset, text)
default:
return mime.QEncoding.Encode(charset, text)
}
*/
}
// getHeaders returns the message headers
func (msg *message) getHeaders() (headers string) {
// if the date header isn't set, set it
if date := msg.headers.Get("Date"); date == "" {
msg.headers.Set("Date", time.Now().Format(time.RFC1123Z))
}
// encode and combine the headers
for header, values := range msg.headers {
headers += header + ": " + encodeHeader(strings.Join(values, ", "), msg.charset, len(header) + 2) + "\r\n"
}
headers = headers + "\r\n"
return
}
// getCID gets the generated CID for the provided text
func (msg *message) getCID(text string) (cid string) {
// set the date format to use
const dateFormat = "20060102.150405"
// get the cid if we have one
cid, exists := msg.cids[text]
if !exists {
// generate a new cid
cid = time.Now().Format(dateFormat) + "." + strconv.Itoa(len(msg.cids)+1) + "@mail.0"
// save it
msg.cids[text] = cid
}
return
}
// replaceCIDs replaces the CIDs found in a text string
// with generated ones
func (msg *message) replaceCIDs(text string) string {
// regular expression to find cids
re := regexp.MustCompile(`(src|href)="cid:(.*?)"`)
// replace all of the found cids with generated ones
for _, matches := range re.FindAllStringSubmatch(text, -1) {
cid := msg.getCID(matches[2])
text = strings.Replace(text, "cid:"+matches[2], "cid:"+cid, -1)
}
return text
}
// openMultipart creates a new part of a multipart message
func (msg *message) openMultipart(multipartType string) {
// create a new multipart writer
msg.writers = append(msg.writers, multipart.NewWriter(msg.body))
// create the boundary
contentType := "multipart/" + multipartType + ";\n \tboundary=" + msg.writers[msg.parts].Boundary()
// if no existing parts, add header to main header group
if msg.parts == 0 {
msg.headers.Set("Content-Type", contentType)
} else { // add header to multipart section
header := make(textproto.MIMEHeader)
header.Set("Content-Type", contentType)
msg.writers[msg.parts-1].CreatePart(header)
}
msg.parts++
}
// closeMultipart closes a part of a multipart message
func (msg *message) closeMultipart() {
if msg.parts > 0 {
msg.writers[msg.parts-1].Close()
msg.parts--
}
}
// base64Encode base64 encodes the provided text with line wrapping
func base64Encode(text []byte) []byte {
// create buffer
buf := new(bytes.Buffer)
// create base64 encoder that linewraps
encoder := base64.NewEncoder(base64.StdEncoding, &base64LineWrap{writer: buf})
// write the encoded text to buf
encoder.Write(text)
encoder.Close()
return buf.Bytes()
}
// qpEncode uses the quoted-printable encoding to encode the provided text
func qpEncode(text []byte) []byte {
// create buffer
buf := new(bytes.Buffer)
encoder := quotedprintable.NewWriter(buf)
encoder.Write(text)
encoder.Close()
return buf.Bytes()
}
const maxLineChars = 76
type base64LineWrap struct {
writer io.Writer
numLineChars int
}
func (e *base64LineWrap) Write(p []byte) (n int, err error) {
n = 0
// while we have more chars than are allowed
for len(p)+e.numLineChars > maxLineChars {
numCharsToWrite := maxLineChars - e.numLineChars
// write the chars we can
e.writer.Write(p[:numCharsToWrite])
// write a line break
e.writer.Write([]byte("\r\n"))
// reset the line count
e.numLineChars = 0
// remove the chars that have been written
p = p[numCharsToWrite:]
// set the num of chars written
n += numCharsToWrite
}
// write what is left
e.writer.Write(p)
e.numLineChars += len(p)
n += len(p)
return
}
func (msg *message) write(header textproto.MIMEHeader, body []byte, encoding encoding) {
msg.writeHeader(header)
msg.writeBody(body, encoding)
}
func (msg *message) writeHeader(headers textproto.MIMEHeader) {
// if there are no parts add header to main headers
if msg.parts == 0 {
for header, value := range headers {
msg.headers[header] = value
}
} else { // add header to multipart section
msg.writers[msg.parts-1].CreatePart(headers)
}
}
func (msg *message) writeBody(body []byte, encoding encoding) {
// encode and write the body
switch encoding {
case EncodingQuotedPrintable:
msg.body.Write(qpEncode(body))
case EncodingBase64:
msg.body.Write(base64Encode(body))
default:
msg.body.Write(body)
}
}
func (msg *message) addBody(contentType string, body []byte) {
body = []byte(msg.replaceCIDs(string(body)))
header := make(textproto.MIMEHeader)
header.Set("Content-Type", contentType+"; charset="+msg.charset)
header.Set("Content-Transfer-Encoding", msg.encoding.String())
msg.write(header, body, msg.encoding)
}
var quoteEscaper = strings.NewReplacer("\\", "\\\\", `"`, "\\\"")
func escapeQuotes(s string) string {
return quoteEscaper.Replace(s)
}
func (msg *message) addFiles(files []*file, inline bool) {
encoding := EncodingBase64
for _, file := range files {
header := make(textproto.MIMEHeader)
header.Set("Content-Type", file.mimeType+";\n \tname=\""+encodeHeader(escapeQuotes(file.filename), msg.charset, 6)+`"`)
header.Set("Content-Transfer-Encoding", encoding.String())
if inline {
header.Set("Content-Disposition", "inline;\n \tfilename=\""+encodeHeader(escapeQuotes(file.filename), msg.charset, 10)+`"`)
header.Set("Content-ID", "<"+msg.getCID(file.filename)+">")
} else {
header.Set("Content-Disposition", "attachment;\n \tfilename=\""+encodeHeader(escapeQuotes(file.filename), msg.charset, 10)+`"`)
}
msg.write(header, file.data, encoding)
}
}