Fix leak of first recipient to other recipients because mail headers are also cached and re-used

mail_common.go

@@ -3,14 +3,12 @@
 package main
 
 import (
-	"crypto/tls"
 	"fmt"
 	"mime"
 	"mime/quotedprintable"
 	"net/mail"
 	"net/smtp"
 	"strings"
-	"time"
 )
 
 type MailContent struct {
@@ -49,30 +47,30 @@ type SmtpSettings struct {
 	Password string `json:"password"`
 }
 
-func sendNotices(recipient string, notices []*WidNotice, template MailTemplate, auth smtp.Auth, smtpConfig SmtpSettings, cache *map[string][]byte) error {
+func sendNotices(recipient string, notices []*WidNotice, template MailTemplate, auth smtp.Auth, smtpConfig SmtpSettings, mailContentCache *map[string]*MailContent) error {
 	logger.debug("Generating and sending mails for recipient " + recipient + " ...")
 	cacheHits := 0
 	cacheMisses := 0
-	mails := [][]byte{}
+	mails := []*MailContent{}
 	for _, n := range notices {
-		var data []byte
+		var mc *MailContent
-		cacheResult := (*cache)[n.Uuid]
+		cacheResult := (*mailContentCache)[n.Uuid]
-		if len(cacheResult) > 0 {
+		if cacheResult != nil {
 			cacheHits++
-			data = cacheResult
+			mc = cacheResult
 		} else {
 			cacheMisses++
-			mailContent, err := template.generate(TemplateData{n, Version})
+			mc_, err := template.generate(TemplateData{n, Version})
 			if err != nil {
 				logger.error("Could not create mail from template")
 				logger.error(err)
+			} else {
+				mc = &mc_
+				// add to cache
+				(*mailContentCache)[n.Uuid] = mc
 			}
-			// serialize mail
-			data = mailContent.serializeValidMail(smtpConfig.From, recipient)
-			// add to cache
-			(*cache)[n.Uuid] = data
 		}
-		mails = append(mails, data)
+		mails = append(mails, mc)
 	}
 	logger.debug(fmt.Sprintf("%v mail cache hits, %v misses", cacheHits, cacheMisses))
 	err := sendMails(
@@ -86,48 +84,6 @@ func sendNotices(recipient string, notices []*WidNotice, template MailTemplate,
 	return nil
 }
 
-func sendMails(smtpConf SmtpSettings, auth smtp.Auth, to string, data [][]byte) error {
-	addr := fmt.Sprintf("%v:%v", smtpConf.ServerHost, smtpConf.ServerPort)
-	logger.debug("Connecting to mail server at " + addr + " ...")
-	connection, err := smtp.Dial(addr)
-	if err != nil { return err }
-	defer connection.Close()
-	// can leave out connection.Hello
-	hasTlsExt, _ := connection.Extension("starttls")
-	if hasTlsExt {
-		err = connection.StartTLS(&tls.Config{ServerName: smtpConf.ServerHost})
-		if err != nil { return err }
-		logger.debug("Mail Server supports TLS")
-	} else {
-		logger.debug("Mail Server doesn't support TLS")
-	}
-	logger.debug("Authenticating to mail server ...")
-	err = connection.Auth(auth)
-	if err != nil { return err }
-	if logger.LogLevel >= 3 {
-		fmt.Printf("DEBUG %v Sending mails to server ", time.Now().Format("2006/01/02 15:04:05.000000"))
-	}
-	for _, d := range data {
-		err = connection.Mail(smtpConf.From)
-		if err != nil { return err }
-		err = connection.Rcpt(to)
-		if err != nil { return err }
-		writer, err := connection.Data()
-		if err != nil { return err }
-		_, err = writer.Write(d)
-		if err != nil { return err }
-		err = writer.Close()
-		if err != nil { return err }
-		if logger.LogLevel >= 3 {
-			print(".")
-		}
-	}
-	if logger.LogLevel >= 3 {
-		print("\n")
-	}
-	return connection.Quit()
-}
-
 func mailAddressIsValid(address string) bool {
 	_, err := mail.ParseAddress(address);
 	return err == nil

mail_transfer.go

@@ -0,0 +1,57 @@
+// +build !debug_mail_transfer
+// Copyright (c) 2023 Julian Müller (ChaoticByte)
+
+package main
+
+import (
+	"crypto/tls"
+	"fmt"
+	"net/smtp"
+	"time"
+)
+
+
+func sendMails(smtpConf SmtpSettings, auth smtp.Auth, to string, mails []*MailContent) error {
+	addr := fmt.Sprintf("%v:%v", smtpConf.ServerHost, smtpConf.ServerPort)
+	logger.debug("Connecting to mail server at " + addr + " ...")
+	connection, err := smtp.Dial(addr)
+	if err != nil { return err }
+	defer connection.Close()
+	// can leave out connection.Hello
+	hasTlsExt, _ := connection.Extension("starttls")
+	if hasTlsExt {
+		err = connection.StartTLS(&tls.Config{ServerName: smtpConf.ServerHost})
+		if err != nil { return err }
+		logger.debug("Mail Server supports StartTLS")
+	} else {
+		logger.debug("Mail Server doesn't support StartTLS")
+	}
+	logger.debug("Authenticating to mail server ...")
+	err = connection.Auth(auth)
+	if err != nil { return err }
+	if logger.LogLevel >= 3 {
+		fmt.Printf("DEBUG %v Sending mails to server ", time.Now().Format("2006/01/02 15:04:05.000000"))
+	}
+	for _, mc := range mails {
+		// serialize mail
+		d := mc.serializeValidMail(smtpConf.From, to)
+		// send mail
+		err = connection.Mail(smtpConf.From)
+		if err != nil { return err }
+		err = connection.Rcpt(to)
+		if err != nil { return err }
+		writer, err := connection.Data()
+		if err != nil { return err }
+		_, err = writer.Write(d)
+		if err != nil { return err }
+		err = writer.Close()
+		if err != nil { return err }
+		if logger.LogLevel >= 3 {
+			print(".")
+		}
+	}
+	if logger.LogLevel >= 3 {
+		print("\n")
+	}
+	return connection.Quit()
+}

mail_transfer_debug.go

@@ -0,0 +1,26 @@
+// +build debug_mail_transfer
+// Copyright (c) 2023 Julian Müller (ChaoticByte)
+
+package main
+
+import (
+	"fmt"
+	"net/smtp"
+)
+
+func sendMails(smtpConf SmtpSettings, auth smtp.Auth, to string, mails []*MailContent) error {
+	logger.warn("Mail Transfer Debugging is active. Not connecting.")
+	logger.info("MAIL TRANSFER: \n\n")
+	for _, mc := range mails {
+		// serialize mail
+		d := mc.serializeValidMail(smtpConf.From, to)
+		// output mail
+		fmt.Println("MAIL FROM:" + smtpConf.From)
+		fmt.Println("RCPT TO:" + to)
+		fmt.Println("DATA")
+		fmt.Println(string(d))
+		fmt.Println(".")
+	}
+	fmt.Print("\n\n")
+	return nil
+}

main.go

@@ -98,7 +98,7 @@ func main() {
 		t1 := time.Now().UnixMilli()
 		newNotices := []WidNotice{}
 		lastPublished := map[string]time.Time{} // endpoint id : last published timestamp
-		cache := map[string][]byte{}            // cache generated emails for reuse
+		cache := map[string]*MailContent{}      // cache generated emails for reuse
 		for _, a := range enabledApiEndpoints {
 			logger.info("Querying endpoint '" + a.Id + "' for new notices ...")
 			n, t, err := a.getNotices(persistent.data.(PersistentData).LastPublished[a.Id])