Allow safe debugging of mail transfer by adding debug_mail_transfer build flag

mail_common.go

@@ -0,0 +1,90 @@
+// Copyright (c) 2023 Julian Müller (ChaoticByte)
+
+package main
+
+import (
+	"fmt"
+	"mime"
+	"mime/quotedprintable"
+	"net/mail"
+	"net/smtp"
+	"strings"
+)
+
+type MailContent struct {
+	Subject string
+	Body string
+}
+
+func (c MailContent) serializeValidMail(from string, to string) []byte {
+	// format subject using Q Encoding from RFC2047
+	subjectEncoded := mime.QEncoding.Encode("utf-8", c.Subject)
+	// format body using Quoted-Printable Encoding from RFC2045
+	var bodyEncoded strings.Builder
+	bew := quotedprintable.NewWriter(&bodyEncoded)
+	bew.Write([]byte(c.Body))
+	bew.Close()
+	// glue it all together
+	data := fmt.Appendf(nil, 
+		"Content-Type: text/plain; charset=\"utf-8\"\r\nContent-Transfer-Encoding: Quoted-Printable\r\nFrom: %v\r\nTo: %v\r\nSubject: %v\r\n\r\n%v",
+		from, to, subjectEncoded, bodyEncoded.String(),
+	)
+	return data
+}
+
+type NotifyList struct {
+	Name string `json:"name"`
+	Recipients []string `json:"recipients"`
+	// Must be a configured filter id
+	Filter []Filter `json:"filter"`
+}
+
+type SmtpSettings struct {
+	From string `json:"from"`
+	ServerHost string `json:"host"`
+	ServerPort int `json:"port"`
+	User string `json:"user"`
+	Password string `json:"password"`
+}
+
+func sendNotices(recipient string, notices []*WidNotice, template MailTemplate, auth smtp.Auth, smtpConfig SmtpSettings, cache *map[string][]byte) error {
+	logger.debug("Generating and sending mails for recipient " + recipient + " ...")
+	cacheHits := 0
+	cacheMisses := 0
+	mails := [][]byte{}
+	for _, n := range notices {
+		var data []byte
+		cacheResult := (*cache)[n.Uuid]
+		if len(cacheResult) > 0 {
+			cacheHits++
+			data = cacheResult
+		} else {
+			cacheMisses++
+			mailContent, err := template.generate(TemplateData{n, Version})
+			if err != nil {
+				logger.error("Could not create mail from template")
+				logger.error(err)
+			}
+			// serialize mail
+			data = mailContent.serializeValidMail(smtpConfig.From, recipient)
+			// add to cache
+			(*cache)[n.Uuid] = data
+		}
+		mails = append(mails, data)
+	}
+	logger.debug(fmt.Sprintf("%v mail cache hits, %v misses", cacheHits, cacheMisses))
+	err := sendMails(
+		smtpConfig,
+		auth,
+		recipient,
+		mails,
+	)
+	if err != nil { return err }
+	logger.debug("Successfully sent all mails to " + recipient)
+	return nil
+}
+
+func mailAddressIsValid(address string) bool {
+	_, err := mail.ParseAddress(address);
+	return err == nil
+}