125 lines
2.3 KiB
Go
125 lines
2.3 KiB
Go
package utils
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import (
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"crypto"
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"crypto/x509"
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"encoding/pem"
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"strings"
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"time"
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"github.com/emersion/go-msgauth/dkim"
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)
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// MTA is mail transfer agent
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type MTA interface {
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Send(from, to, data string) error
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}
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// Email object
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type Email struct {
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data strings.Builder
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Date string
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MessageID string
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InReplyTo string
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From string
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To string
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Subject string
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Text string
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HTML string
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Files []*File
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}
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// NewEmail constructs Email object
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func NewEmail(messageID, inReplyTo, subject, from, to, text, html string, files []*File) *Email {
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email := &Email{
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Date: time.Now().UTC().Format(time.RFC1123Z),
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MessageID: messageID,
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InReplyTo: inReplyTo,
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From: from,
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To: to,
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Subject: subject,
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Text: text,
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HTML: html,
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Files: files,
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}
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if html != "" {
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var err error
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html, err = StripHTMLTag(html, "style")
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if err == nil {
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email.HTML = html
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}
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}
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return email
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}
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// Compose converts email object to string and (optionally) signs it
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func (e *Email) Compose(privkey string) string {
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domain := strings.SplitN(e.From, "@", 2)[0]
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e.data.WriteString("From: ")
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e.data.WriteString(e.From)
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e.data.WriteString("\r\n")
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e.data.WriteString("To: ")
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e.data.WriteString(e.To)
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e.data.WriteString("\r\n")
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e.data.WriteString("Message-Id: ")
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e.data.WriteString(e.MessageID)
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e.data.WriteString("\r\n")
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e.data.WriteString("Date: ")
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e.data.WriteString(e.Date)
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e.data.WriteString("\r\n")
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if e.InReplyTo != "" {
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e.data.WriteString("In-Reply-To: ")
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e.data.WriteString(e.InReplyTo)
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e.data.WriteString("\r\n")
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}
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e.data.WriteString("Subject: ")
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e.data.WriteString(e.Subject)
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e.data.WriteString("\r\n")
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e.data.WriteString("\r\n")
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e.data.WriteString(e.Text)
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e.data.WriteString("\r\n")
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e.sign(domain, privkey)
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return e.data.String()
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}
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func (e *Email) sign(domain, privkey string) {
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if privkey == "" {
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return
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}
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pemblock, _ := pem.Decode([]byte(privkey))
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if pemblock == nil {
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return
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}
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parsedkey, err := x509.ParsePKCS8PrivateKey(pemblock.Bytes)
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if err != nil {
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return
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}
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signer := parsedkey.(crypto.Signer)
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options := &dkim.SignOptions{
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Domain: domain,
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Selector: "postmoogle",
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Signer: signer,
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}
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var msg strings.Builder
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err = dkim.Sign(&msg, strings.NewReader(e.data.String()), options)
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if err != nil {
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return
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}
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e.data = msg
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}
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