mail 实现ssl

由于我们使用的阿里云服务器不能telnet 25端口，发送ssl时候感觉很蹩脚，就自己写了一个go mail 发送

2、main.go

// main.go
package main

import (
“flag”
“fmt”
“io/ioutil”
“log”
“net/smtp”
“os”
“sslmail/mymail”
“strings”
)

func SendMail(fromuser, password, subject, host, port, bodyfile, bodyhtmlfile string, tousers, attachs []string) error {
// NewEmail返回一个email结构体的指针
e := mymail.NewEmail()
// 发件人
e.From = fromuser
// 收件人(可以有多个)
e.To = tousers
// 邮件主题
e.Subject = subject
// 解析html模板
//body := new(bytes.Buffer)
if strings.TrimSpace(bodyfile) != “” {
f, err := os.OpenFile(bodyfile, os.O_RDONLY, 0600)
if err != nil {
fmt.Println(err)
} else {
contentBytes, err := ioutil.ReadAll(f)
if err != nil {
fmt.Println(“读取文件失败”)
} else {
e.Text = contentBytes
}
}
}

if strings.TrimSpace(bodyhtmlfile) != "" {

	ft, err := os.OpenFile(bodyhtmlfile, os.O_RDONLY, 0600)

	if err != nil {

		fmt.Println(err)

	} else {

		htmlBytes, err := ioutil.ReadAll(ft)

		if err != nil {

			fmt.Println("读取文件失败")

		} else {

			e.HTML = htmlBytes

		}

	}

}



if len(attachs) > 0 {

	for _, v := range attachs {

		e.AttachFile(v)

	}

}

addr := host + ":" + port

//fmt.Println(addr)

// 发送邮件(如果使用QQ邮箱发送邮件的话，passwd不是邮箱密码而是授权码)

return e.Send(addr, smtp.PlainAuth("", fromuser, password, host)) }

type sliceValue []string

func newSliceValue(vals []string, p []string) *sliceValue {
*p = vals
return (sliceValue)(p)
}

func (s *sliceValue) Set(val string) error {
*s = sliceValue(strings.Split(val, “,”))
return nil
}

func (s sliceValue) Get() interface{} { return []string(s) }

func (s sliceValue) String() string { return strings.Join([]string(s), “,”) }

func main() {

//fromuser := "name@yourmail.com"

fromuser := flag.String("fromuser", "name@yourmail.com", "sender email info")

password := flag.String("password", "your password default", "sender email password")

var tousers []string

flag.Var(newSliceValue([]string{}, &tousers), "tousers", "your `tousers` email separated by ','")

subject := flag.String("subject", "hello,world", "subject")

host := flag.String("host", "smtp.qiye.163.com", "ssl url info")

port := flag.String("port", "465", "ssl port")

bodyfile := flag.String("bodyfile", "", "the body file your password default")

bodyhtmlfile := flag.String("bodyhtmlfile", "", "the body html file your password default")

var attachs []string

flag.Var(newSliceValue([]string{}, &attachs), "attachs", "your `attachs` email separated by ','")

//htmlbody := flag.String("htmlbody", "a html file ", "you can describe you mail")

flag.Parse()

//fmt.Println(attachs)

err := SendMail(*fromuser, *password, *subject, *host, *port, *bodyfile, *bodyhtmlfile, tousers, attachs)

if err != nil {

	log.Println("发送邮件失败")

	//log.Println(err)

	return

}

log.Println("发送邮件成功") } 3、mymail/email.go

// Package email is designed to provide an “email interface for humans.”
// Designed to be robust and flexible, the email package aims to make sending email easy without getting in the way.
package mymail

import (
“bufio”
“bytes”
“crypto/rand”
“crypto/tls”
“encoding/base64”
“errors”
“fmt”
“io”
“log”
“math”
“math/big”
“mime”
“mime/multipart”
“mime/quotedprintable”
“net”
“net/mail”
“net/smtp”
“net/textproto”
“os”
“path/filepath”
“strings”
“time”
“unicode”
)

const (
MaxLineLength = 76 // MaxLineLength is the maximum line length per RFC 2045
defaultContentType = “text/plain; charset=us-ascii” // defaultContentType is the default Content-Type according to RFC 2045, section 5.2
)

// ErrMissingBoundary is returned when there is no boundary given for a multipart entity
var ErrMissingBoundary = errors.New(“No boundary found for multipart entity”)

// ErrMissingContentType is returned when there is no “Content-Type” header for a MIME entity
var ErrMissingContentType = errors.New(“No Content-Type found for MIME entity”)

// Email is the type used for email messages
type Email struct {
ReplyTo []string
From string
To []string
Bcc []string
Cc []string
Subject string
Text []byte // Plaintext message (optional)
HTML []byte // Html message (optional)
Sender string // override From as SMTP envelope sender (optional)
Headers textproto.MIMEHeader
Attachments []*Attachment
ReadReceipt []string
}

// part is a copyable representation of a multipart.Part
type part struct {
header textproto.MIMEHeader
body []byte
}

// NewEmail creates an Email, and returns the pointer to it.
func NewEmail() *Email {
return &Email{Headers: textproto.MIMEHeader{}}
}

// trimReader is a custom io.Reader that will trim any leading
// whitespace, as this can cause email imports to fail.
type trimReader struct {
rd io.Reader
}

// Read trims off any unicode whitespace from the originating reader
func (tr trimReader) Read(buf []byte) (int, error) {
n, err := tr.rd.Read(buf)
t := bytes.TrimLeftFunc(buf[:n], unicode.IsSpace)
n = copy(buf, t)
return n, err
}

// NewEmailFromReader reads a stream of bytes from an io.Reader, r,
// and returns an email struct containing the parsed data.
// This function expects the data in RFC 5322 format.
func NewEmailFromReader(r io.Reader) (*Email, error) {
e := NewEmail()
s := trimReader{rd: r}
tp := textproto.NewReader(bufio.NewReader(s))
// Parse the main headers
hdrs, err := tp.ReadMIMEHeader()
if err != nil {
return e, err
}
// Set the subject, to, cc, bcc, and from
for h, v := range hdrs {
switch {
case h == “Subject”:
e.Subject = v[0]
subj, err := (&mime.WordDecoder{}).DecodeHeader(e.Subject)
if err == nil && len(subj) > 0 {
e.Subject = subj
}
delete(hdrs, h)
case h == “To”:
for _, to := range v {
tt, err := (&mime.WordDecoder{}).DecodeHeader(to)
if err == nil {
e.To = append(e.To, tt)
} else {
e.To = append(e.To, to)
}
}
delete(hdrs, h)
case h == “Cc”:
for _, cc := range v {
tcc, err := (&mime.WordDecoder{}).DecodeHeader(cc)
if err == nil {
e.Cc = append(e.Cc, tcc)
} else {
e.Cc = append(e.Cc, cc)
}
}
delete(hdrs, h)
case h == “Bcc”:
for _, bcc := range v {
tbcc, err := (&mime.WordDecoder{}).DecodeHeader(bcc)
if err == nil {
e.Bcc = append(e.Bcc, tbcc)
} else {
e.Bcc = append(e.Bcc, bcc)
}
}
delete(hdrs, h)
case h == “From”:
e.From = v[0]
fr, err := (&mime.WordDecoder{}).DecodeHeader(e.From)
if err == nil && len(fr) > 0 {
e.From = fr
}
delete(hdrs, h)
}
}
e.Headers = hdrs
body := tp.R
// Recursively parse the MIME parts
ps, err := parseMIMEParts(e.Headers, body)
if err != nil {
return e, err
}
for _, p := range ps {
if ct := p.header.Get(“Content-Type”); ct == “” {
return e, ErrMissingContentType
}
ct, _, err := mime.ParseMediaType(p.header.Get(“Content-Type”))
if err != nil {
return e, err
}
switch {
case ct == “text/plain”:
e.Text = p.body
case ct == “text/html”:
e.HTML = p.body
}
}
return e, nil
}

// parseMIMEParts will recursively walk a MIME entity and return a []mime.Part containing
// each (flattened) mime.Part found.
// It is important to note that there are no limits to the number of recursions, so be
// careful when parsing unknown MIME structures!
func parseMIMEParts(hs textproto.MIMEHeader, b io.Reader) ([]part, error) {
var ps []part
// If no content type is given, set it to the default
if _, ok := hs[“Content-Type”]; !ok {
hs.Set(“Content-Type”, defaultContentType)
}
ct, params, err := mime.ParseMediaType(hs.Get(“Content-Type”))
if err != nil {
return ps, err
}
// If it’s a multipart email, recursively parse the parts
if strings.HasPrefix(ct, “multipart/”) {
if _, ok := params[“boundary”]; !ok {
return ps, ErrMissingBoundary
}
mr := multipart.NewReader(b, params[“boundary”])
for {
var buf bytes.Buffer
p, err := mr.NextPart()
if err == io.EOF {
break
}
if err != nil {
return ps, err
}
if _, ok := p.Header[“Content-Type”]; !ok {
p.Header.Set(“Content-Type”, defaultContentType)
}
subct, _, err := mime.ParseMediaType(p.Header.Get(“Content-Type”))
if err != nil {
return ps, err
}
if strings.HasPrefix(subct, “multipart/”) {
sps, err := parseMIMEParts(p.Header, p)
if err != nil {
return ps, err
}
ps = append(ps, sps…)
} else {
var reader io.Reader
reader = p
const cte = “Content-Transfer-Encoding”
if p.Header.Get(cte) == “base64” {
reader = base64.NewDecoder(base64.StdEncoding, reader)
}
// Otherwise, just append the part to the list
// Copy the part data into the buffer
if _, err := io.Copy(&buf, reader); err != nil {
return ps, err
}
ps = append(ps, &part{body: buf.Bytes(), header: p.Header})
}
}
} else {
// If it is not a multipart email, parse the body content as a single “part”
var buf bytes.Buffer
if _, err := io.Copy(&buf, b); err != nil {
return ps, err
}
ps = append(ps, &part{body: buf.Bytes(), header: hs})
}
return ps, nil
}

// Attach is used to attach content from an io.Reader to the email.
// Required parameters include an io.Reader, the desired filename for the attachment, and the Content-Type
// The function will return the created Attachment for reference, as well as nil for the error, if successful.
func (e *Email) Attach(r io.Reader, filename string, c string) (a *Attachment, err error) {
var buffer bytes.Buffer
if _, err = io.Copy(&buffer, r); err != nil {
return
}
at := &Attachment{
Filename: filename,
Header: textproto.MIMEHeader{},
Content: buffer.Bytes(),
}
// Get the Content-Type to be used in the MIMEHeader
if c != “” {
at.Header.Set(“Content-Type”, c)
} else {
// If the Content-Type is blank, set the Content-Type to “application/octet-stream”
at.Header.Set(“Content-Type”, “application/octet-stream”)
}
at.Header.Set(“Content-Disposition”, fmt.Sprintf(“attachment;\r\n filename="%s"”, filename))
at.Header.Set(“Content-ID”, fmt.Sprintf(“<%s>”, filename))
at.Header.Set(“Content-Transfer-Encoding”, “base64”)
e.Attachments = append(e.Attachments, at)
return at, nil
}

// AttachFile is used to attach content to the email.
// It attempts to open the file referenced by filename and, if successful, creates an Attachment.
// This Attachment is then appended to the slice of Email.Attachments.
// The function will then return the Attachment for reference, as well as nil for the error, if successful.
func (e *Email) AttachFile(filename string) (a *Attachment, err error) {
f, err := os.Open(filename)
if err != nil {
return
}
defer f.Close()

ct := mime.TypeByExtension(filepath.Ext(filename))

basename := filepath.Base(filename)

return e.Attach(f, basename, ct) }

// msgHeaders merges the Email’s various fields and custom headers together in a
// standards compliant way to create a MIMEHeader to be used in the resulting
// message. It does not alter e.Headers.
//
// “e”’s fields To, Cc, From, Subject will be used unless they are present in
// e.Headers. Unless set in e.Headers, “Date” will filled with the current time.
func (e *Email) msgHeaders() (textproto.MIMEHeader, error) {
res := make(textproto.MIMEHeader, len(e.Headers)+4)
if e.Headers != nil {
for _, h := range []string{“Reply-To”, “To”, “Cc”, “From”, “Subject”, “Date”, “Message-Id”, “MIME-Version”} {
if v, ok := e.Headers[h]; ok {
res[h] = v
}
}
}
// Set headers if there are values.
if _, ok := res[“Reply-To”]; !ok && len(e.ReplyTo) > 0 {
res.Set(“Reply-To”, strings.Join(e.ReplyTo, “, “))
}
if _, ok := res[“To”]; !ok && len(e.To) > 0 {
res.Set(“To”, strings.Join(e.To, “, “))
}
if _, ok := res[“Cc”]; !ok && len(e.Cc) > 0 {
res.Set(“Cc”, strings.Join(e.Cc, “, “))
}
if _, ok := res[“Subject”]; !ok && e.Subject != “” {
res.Set(“Subject”, e.Subject)
}
if _, ok := res[“Message-Id”]; !ok {
id, err := generateMessageID()
if err != nil {
return nil, err
}
res.Set(“Message-Id”, id)
}
// Date and From are required headers.
if _, ok := res[“From”]; !ok {
res.Set(“From”, e.From)
}
if _, ok := res[“Date”]; !ok {
res.Set(“Date”, time.Now().Format(time.RFC1123Z))
}
if _, ok := res[“MIME-Version”]; !ok {
res.Set(“MIME-Version”, “1.0”)
}
for field, vals := range e.Headers {
if _, ok := res[field]; !ok {
res[field] = vals
}
}
return res, nil
}

func writeMessage(buff io.Writer, msg []byte, multipart bool, mediaType string, w *multipart.Writer) error {
if multipart {
header := textproto.MIMEHeader{
“Content-Type”: {mediaType + “; charset=UTF-8”},
“Content-Transfer-Encoding”: {“quoted-printable”},
}
if _, err := w.CreatePart(header); err != nil {
return err
}
}

qp := quotedprintable.NewWriter(buff)

// Write the text

if _, err := qp.Write(msg); err != nil {

    return err

}

return qp.Close() }

// Bytes converts the Email object to a []byte representation, including all needed MIMEHeaders, boundaries, etc.
func (e *Email) Bytes() ([]byte, error) {
// TODO: better guess buffer size
buff := bytes.NewBuffer(make([]byte, 0, 4096))

headers, err := e.msgHeaders()

if err != nil {

    return nil, err

}



var (

    isMixed       = len(e.Attachments) > 0

    isAlternative = len(e.Text) > 0 && len(e.HTML) > 0

)



var w *multipart.Writer

if isMixed || isAlternative {

    w = multipart.NewWriter(buff)

}

switch {

case isMixed:

    headers.Set("Content-Type", "multipart/mixed;\r\n boundary="+w.Boundary())

case isAlternative:

    headers.Set("Content-Type", "multipart/alternative;\r\n boundary="+w.Boundary())

case len(e.HTML) > 0:

    headers.Set("Content-Type", "text/html; charset=UTF-8")

    headers.Set("Content-Transfer-Encoding", "quoted-printable")

default:

    headers.Set("Content-Type", "text/plain; charset=UTF-8")

    headers.Set("Content-Transfer-Encoding", "quoted-printable")

}

headerToBytes(buff, headers)

_, err = io.WriteString(buff, "\r\n")

if err != nil {

    return nil, err

}



// Check to see if there is a Text or HTML field

if len(e.Text) > 0 || len(e.HTML) > 0 {

    var subWriter *multipart.Writer



    if isMixed && isAlternative {

        // Create the multipart alternative part

        subWriter = multipart.NewWriter(buff)

        header := textproto.MIMEHeader{

            "Content-Type": {"multipart/alternative;\r\n boundary=" + subWriter.Boundary()},

        }

        if _, err := w.CreatePart(header); err != nil {

            return nil, err

        }

    } else {

        subWriter = w

    }

    // Create the body sections

    if len(e.Text) > 0 {

        // Write the text

        if err := writeMessage(buff, e.Text, isMixed || isAlternative, "text/plain", subWriter); err != nil {

            return nil, err

        }

    }

    if len(e.HTML) > 0 {

        // Write the HTML

        if err := writeMessage(buff, e.HTML, isMixed || isAlternative, "text/html", subWriter); err != nil {

            return nil, err

        }

    }

    if isMixed && isAlternative {

        if err := subWriter.Close(); err != nil {

            return nil, err

        }

    }

}

// Create attachment part, if necessary

for _, a := range e.Attachments {

    ap, err := w.CreatePart(a.Header)

    if err != nil {

        return nil, err

    }

    // Write the base64Wrapped content to the part

    base64Wrap(ap, a.Content)

}

if isMixed || isAlternative {

    if err := w.Close(); err != nil {

        return nil, err

    }

}

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 {
// 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()
if err != nil {
return err
}
return SendMailUsingTLS(addr, a, sender, to, raw)
}

// Select and parse an SMTP envelope sender address. Choose Email.Sender if set, or fallback to Email.From.
func (e *Email) parseSender() (string, error) {
if e.Sender != “” {
sender, err := mail.ParseAddress(e.Sender)
if err != nil {
return “”, err
}
return sender.Address, nil
} else {
from, err := mail.ParseAddress(e.From)
if err != nil {
return “”, err
}
return from.Address, nil
}
}

// Attachment is a struct representing an email attachment.
// Based on the mime/multipart.FileHeader struct, Attachment contains the name, MIMEHeader, and content of the attachment in question
type Attachment struct {
Filename string
Header textproto.MIMEHeader
Content []byte
}

// base64Wrap encodes the attachment content, and wraps it according to RFC 2045 standards (every 76 chars)
// The output is then written to the specified io.Writer
func base64Wrap(w io.Writer, b []byte) {
// 57 raw bytes per 76-byte base64 line.
const maxRaw = 57
// Buffer for each line, including trailing CRLF.
buffer := make([]byte, MaxLineLength+len(“\r\n”))
copy(buffer[MaxLineLength:], “\r\n”)
// Process raw chunks until there’s no longer enough to fill a line.
for len(b) >= maxRaw {
base64.StdEncoding.Encode(buffer, b[:maxRaw])
w.Write(buffer)
b = b[maxRaw:]
}
// Handle the last chunk of bytes.
if len(b) > 0 {
out := buffer[:base64.StdEncoding.EncodedLen(len(b))]
base64.StdEncoding.Encode(out, b)
out = append(out, “\r\n”…)
w.Write(out)
}
}

// headerToBytes renders “header” to “buff”. If there are multiple values for a
// field, multiple “Field: value\r\n” lines will be emitted.
func headerToBytes(buff io.Writer, header textproto.MIMEHeader) {
for field, vals := range header {
for _, subval := range vals {
// bytes.Buffer.Write() never returns an error.
io.WriteString(buff, field)
io.WriteString(buff, “: “)
// Write the encoded header if needed
switch {
case field == “Content-Type” || field == “Content-Disposition”:
buff.Write([]byte(subval))
default:
buff.Write([]byte(mime.QEncoding.Encode(“UTF-8”, subval)))
}
io.WriteString(buff, “\r\n”)
}
}
}

var maxBigInt = big.NewInt(math.MaxInt64)

// generateMessageID generates and returns a string suitable for an RFC 2822
// compliant Message-ID, e.g.:
// 1444789264909237300.3464.1819418242800517193@DESKTOP01
//
// The following parameters are used to generate a Message-ID:
// - The nanoseconds since Epoch
// - The calling PID
// - A cryptographically random int64
// - The sending hostname
func generateMessageID() (string, error) {
t := time.Now().UnixNano()
pid := os.Getpid()
rint, err := rand.Int(rand.Reader, maxBigInt)
if err != nil {
return “”, err
}
h, err := os.Hostname()
// If we can’t get the hostname, we’ll use localhost
if err != nil {
h = “localhost.localdomain”
}
msgid := fmt.Sprintf(“<%d.%d.%d@%s>”, t, pid, rint, h)
return msgid, nil
}

func Dial(addr string) (*smtp.Client, error) {
conn, err := tls.Dial(“tcp”, addr, nil)
if err != nil {
log.Println(“Dialing Error:”, err)
return nil, err
}
//分解主机端口字符串
host, _, _ := net.SplitHostPort(addr)
return smtp.NewClient(conn, host)
}

//参考net/smtp的func SendMail()
//使用net.Dial连接tls(ssl)端口时,smtp.NewClient()会卡住且不提示err
//len(to)>1时,to[1]开始提示是密送
func SendMailUsingTLS(addr string, auth smtp.Auth, from string,
to []string, msg []byte) (err error) {

//create smtp client

c, err := Dial(addr)

if err != nil {

    log.Println("Create smpt client error:", err)

    return err

}

defer c.Close()



if auth != nil {

    if ok, _ := c.Extension("AUTH"); ok {

        if err = c.Auth(auth); err != nil {

            log.Println("Error during AUTH", err)

            return err

        }

    }

}



if err = c.Mail(from); 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(msg)

if err != nil {

    return err

}



err = w.Close()

if err != nil {

    return err

}



return c.Quit() } 4、build

go build -o sslmail main.go