121 lines
3.2 KiB
Go
121 lines
3.2 KiB
Go
package main
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// TODO: use https://github.com/domodwyer/mailyak as a base lib
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import (
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"bytes"
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"encoding/base64"
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"errors"
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"fmt"
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"log"
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"math/rand"
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"net/mail"
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"strings"
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)
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type EmailHeaders map[string]string
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type EmailConfig struct {
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From string
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To []string
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Subject string
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}
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type EmailCtx struct {
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Headers EmailHeaders
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BodyPlain string
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BodyHtml string
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}
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const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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func RandStringBytes(n int) string {
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b := make([]byte, n)
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for i := range b {
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b[i] = letterBytes[rand.Intn(len(letterBytes))]
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}
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return string(b)
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}
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func (headers EmailHeaders) String() string {
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var buffer bytes.Buffer
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for k, v := range headers {
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buffer.WriteString(fmt.Sprintf("%s: %s\r\n", k, v))
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}
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return buffer.String()
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}
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func NewEmail() *EmailCtx {
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email := EmailCtx{}
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email.Headers = make(EmailHeaders)
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return &email
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}
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func encodeRFC2047(text string) string {
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// use mail's rfc2047 to encode any string
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addr := mail.Address{Name: text, Address: ""}
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return strings.Trim(addr.String(), " \"<@>")
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}
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func (email *EmailCtx) SetHeaders(config EmailConfig) {
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email.Headers["Return-Path"] = config.From
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email.Headers["From"] = config.From
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if len(config.To) < 1 {
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errmsg := "EMAIL_TO must contain at least one value"
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log.Panic(errors.New(errmsg))
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}
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email.Headers["To"] = config.To[0]
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if len(config.To) > 1 {
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email.Headers["Cc"] = strings.Join(config.To[1:], ",")
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}
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email.Headers["Subject"] = encodeRFC2047(config.Subject)
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email.Headers["Content-Transfer-Encoding"] = "quoted-printable"
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email.Headers["MIME-Version"] = "1.0"
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return
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}
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func (email *EmailCtx) SetBody(html string, plain string) {
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email.BodyPlain = plain
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email.BodyHtml = html
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return
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}
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func (email *EmailCtx) String() string {
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var buffer bytes.Buffer
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mixBoundary := RandStringBytes(16)
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altBoundary := RandStringBytes(16)
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buffer.WriteString(email.Headers.String())
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buffer.WriteString(fmt.Sprintf("Content-Type: multipart/mixed;\r\n boundary=\"%s\"\r\n", mixBoundary))
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buffer.WriteString("\r\n")
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buffer.WriteString(fmt.Sprintf("--%s\r\n", mixBoundary))
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buffer.WriteString(fmt.Sprintf("Content-Type: multipart/alternative;\r\n boundary=\"%s\"\r\n", altBoundary))
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buffer.WriteString("\r\n")
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buffer.WriteString(fmt.Sprintf("--%s\r\n", altBoundary))
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buffer.WriteString(fmt.Sprintf("Content-Type: text/plain; charset=\"utf-8\"\r\n"))
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buffer.WriteString(fmt.Sprintf("Content-Transfer-Encoding: base64\r\n"))
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buffer.WriteString("\r\n")
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buffer.WriteString(base64.StdEncoding.EncodeToString([]byte(email.BodyPlain)))
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buffer.WriteString("\r\n")
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buffer.WriteString("\r\n")
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buffer.WriteString(fmt.Sprintf("--%s\r\n", altBoundary))
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buffer.WriteString(fmt.Sprintf("Content-Type: text/html; charset=\"utf-8\"\r\n"))
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buffer.WriteString(fmt.Sprintf("Content-Transfer-Encoding: base64\r\n"))
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buffer.WriteString("\r\n")
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buffer.WriteString(base64.StdEncoding.EncodeToString([]byte(email.BodyHtml)))
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buffer.WriteString("\r\n")
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buffer.WriteString("\r\n")
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buffer.WriteString(fmt.Sprintf("--%s--\r\n", altBoundary))
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buffer.WriteString("\r\n")
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buffer.WriteString(fmt.Sprintf("--%s--\r\n", mixBoundary))
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buffer.WriteString("\r\n")
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return buffer.String()
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}
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