Try to prevent autolinking of displaynames by email readers (#19169)

Unfortunately many email readers will (helpfully) detect url or url-like names and
automatically create links to them, even in HTML emails. This is not ideal when
usernames can have dots in them.

This PR tries to prevent this behaviour by sticking ZWJ characters between dots and
also set the meta tag to prevent format detection.

Not every email template has been changed in this way - just the activation emails but
it may be that we should be setting the above meta tag in all of our emails too.

Signed-off-by: Andrew Thornton <art27@cantab.net>

8 files changed, 38 insertions, 22 deletions

diff --git a/modules/templates/helper.go b/modules/templates/helper.go
index 63c165bc8b..918a6523ba 100644
--- a/modules/templates/helper.go
+++ b/modules/templates/helper.go
@@ -632,6 +632,11 @@ func JSEscape(raw string) string {
 	return template.JSEscapeString(raw)
 }
 
+// DotEscape wraps a dots in names with ZWJ [U+200D] in order to prevent autolinkers from detecting these as urls
+func DotEscape(raw string) string {
+	return strings.ReplaceAll(raw, ".", "\u200d.\u200d")
+}
+
 // Sha1 returns sha1 sum of string
 func Sha1(str string) string {
 	return base.EncodeSha1(str)
diff --git a/services/mailer/mail.go b/services/mailer/mail.go
index 8e04e7e4d2..1e90deb4c4 100644
--- a/services/mailer/mail.go
+++ b/services/mailer/mail.go
@@ -78,8 +78,9 @@ func sendUserMail(language string, u *user_model.User, tpl base.TplName, code, s
 		"Code":              code,
 		"Language":          locale.Language(),
 		// helper
-		"i18n":     locale,
-		"Str2html": templates.Str2html,
+		"i18n":      locale,
+		"Str2html":  templates.Str2html,
+		"DotEscape": templates.DotEscape,
 	}
 
 	var content bytes.Buffer
@@ -128,8 +129,9 @@ func SendActivateEmailMail(u *user_model.User, email *user_model.EmailAddress) {
 		"Email":           email.Email,
 		"Language":        locale.Language(),
 		// helper
-		"i18n":     locale,
-		"Str2html": templates.Str2html,
+		"i18n":      locale,
+		"Str2html":  templates.Str2html,
+		"DotEscape": templates.DotEscape,
 	}
 
 	var content bytes.Buffer
@@ -158,8 +160,9 @@ func SendRegisterNotifyMail(u *user_model.User) {
 		"Username":    u.Name,
 		"Language":    locale.Language(),
 		// helper
-		"i18n":     locale,
-		"Str2html": templates.Str2html,
+		"i18n":      locale,
+		"Str2html":  templates.Str2html,
+		"DotEscape": templates.DotEscape,
 	}
 
 	var content bytes.Buffer
@@ -191,8 +194,9 @@ func SendCollaboratorMail(u, doer *user_model.User, repo *repo_model.Repository)
 		"Link":     repo.HTMLURL(),
 		"Language": locale.Language(),
 		// helper
-		"i18n":     locale,
-		"Str2html": templates.Str2html,
+		"i18n":      locale,
+		"Str2html":  templates.Str2html,
+		"DotEscape": templates.DotEscape,
 	}
 
 	var content bytes.Buffer
@@ -275,8 +279,9 @@ func composeIssueCommentMessages(ctx *mailCommentContext, lang string, recipient
 		"ReviewComments":  reviewComments,
 		"Language":        locale.Language(),
 		// helper
-		"i18n":     locale,
-		"Str2html": templates.Str2html,
+		"i18n":      locale,
+		"Str2html":  templates.Str2html,
+		"DotEscape": templates.DotEscape,
 	}
 
 	var mailSubject bytes.Buffer
diff --git a/services/mailer/mail_release.go b/services/mailer/mail_release.go
index 76dceb2387..b6bddeac04 100644
--- a/services/mailer/mail_release.go
+++ b/services/mailer/mail_release.go
@@ -75,8 +75,9 @@ func mailNewRelease(ctx context.Context, lang string, tos []string, rel *models.
 		"Subject":  subject,
 		"Language": locale.Language(),
 		// helper
-		"i18n":     locale,
-		"Str2html": templates.Str2html,
+		"i18n":      locale,
+		"Str2html":  templates.Str2html,
+		"DotEscape": templates.DotEscape,
 	}
 
 	var mailBody bytes.Buffer
diff --git a/services/mailer/mail_repo.go b/services/mailer/mail_repo.go
index 24e6d671f4..0abc666f1a 100644
--- a/services/mailer/mail_repo.go
+++ b/services/mailer/mail_repo.go
@@ -73,8 +73,9 @@ func sendRepoTransferNotifyMailPerLang(lang string, newOwner, doer *user_model.U
 		"Language":    locale.Language(),
 		"Destination": destination,
 		// helper
-		"i18n":     locale,
-		"Str2html": templates.Str2html,
+		"i18n":      locale,
+		"Str2html":  templates.Str2html,
+		"DotEscape": templates.DotEscape,
 	}
 
 	if err := bodyTemplates.ExecuteTemplate(&content, string(mailRepoTransferNotify), data); err != nil {
diff --git a/templates/mail/auth/activate.tmpl b/templates/mail/auth/activate.tmpl
index 31e9a96882..5de3967bc4 100644
--- a/templates/mail/auth/activate.tmpl
+++ b/templates/mail/auth/activate.tmpl
@@ -2,12 +2,13 @@
 <html>
 <head>
 	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
-	<title>{{.i18n.Tr "mail.activate_account.title" .DisplayName}}</title>
+	<meta name="format-detection" content="telephone=no,date=no,address=no,email=no,url=no"/>
+	<title>{{.i18n.Tr "mail.activate_account.title" (.DisplayName|DotEscape)}}</title>
 </head>
 
 {{ $activate_url := printf "%suser/activate?code=%s" AppUrl (QueryEscape .Code)}}
 <body>
-	<p>{{.i18n.Tr "mail.activate_account.text_1" .DisplayName AppName | Str2html}}</p><br>
+	<p>{{.i18n.Tr "mail.activate_account.text_1" (.DisplayName|DotEscape) AppName | Str2html}}</p><br>
 	<p>{{.i18n.Tr "mail.activate_account.text_2" .ActiveCodeLives | Str2html}}</p><p><a href="{{$activate_url}}">{{$activate_url}}</a></p><br>
 	<p>{{.i18n.Tr "mail.link_not_working_do_paste"}}</p>
 
diff --git a/templates/mail/auth/activate_email.tmpl b/templates/mail/auth/activate_email.tmpl
index 8bd037ae4f..5c79798821 100644
--- a/templates/mail/auth/activate_email.tmpl
+++ b/templates/mail/auth/activate_email.tmpl
@@ -2,12 +2,13 @@
 <html>
 <head>
 	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
-	<title>{{.i18n.Tr "mail.activate_email.title" .DisplayName}}</title>
+	<meta name="format-detection" content="telephone=no,date=no,address=no,email=no,url=no"/>
+	<title>{{.i18n.Tr "mail.activate_email.title" (.DisplayName|DotEscape)}}</title>
 </head>
 
 {{ $activate_url := printf "%suser/activate_email?code=%s&email=%s" AppUrl (QueryEscape .Code) (QueryEscape .Email)}}
 <body>
-	<p>{{.i18n.Tr "mail.hi_user_x" .DisplayName | Str2html}}</p><br>
+	<p>{{.i18n.Tr "mail.hi_user_x" (.DisplayName|DotEscape) | Str2html}}</p><br>
 	<p>{{.i18n.Tr "mail.activate_email.text" .ActiveCodeLives | Str2html}}</p><p><a href="{{$activate_url}}">{{$activate_url}}</a></p><br>
 	<p>{{.i18n.Tr "mail.link_not_working_do_paste"}}</p>
 
diff --git a/templates/mail/auth/register_notify.tmpl b/templates/mail/auth/register_notify.tmpl
index 45ca95f2c3..a32d8ce992 100644
--- a/templates/mail/auth/register_notify.tmpl
+++ b/templates/mail/auth/register_notify.tmpl
@@ -2,12 +2,13 @@
 <html>
 <head>
 	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
-	<title>{{.i18n.Tr "mail.register_notify.title" .DisplayName AppName}}</title>
+	<meta name="format-detection" content="telephone=no,date=no,address=no,email=no,url=no"/>
+	<title>{{.i18n.Tr "mail.register_notify.title" (.DisplayName|DotEscape) AppName}}</title>
 </head>
 
 {{$set_pwd_url := printf "%[1]suser/forgot_password" AppUrl}}
 <body>
-	<p>{{.i18n.Tr "mail.hi_user_x" .DisplayName | Str2html}}</p><br>
+	<p>{{.i18n.Tr "mail.hi_user_x" (.DisplayName|DotEscape) | Str2html}}</p><br>
 	<p>{{.i18n.Tr "mail.register_notify.text_1" AppName}}</p><br>
 	<p>{{.i18n.Tr "mail.register_notify.text_2" .Username}}</p><p><a href="{{AppUrl}}user/login">{{AppUrl}}user/login</a></p><br>
 	<p>{{.i18n.Tr "mail.register_notify.text_3" ($set_pwd_url | Escape) | Str2html}}</p><br>
diff --git a/templates/mail/auth/reset_passwd.tmpl b/templates/mail/auth/reset_passwd.tmpl
index bf10c1f967..028d911a99 100644
--- a/templates/mail/auth/reset_passwd.tmpl
+++ b/templates/mail/auth/reset_passwd.tmpl
@@ -2,12 +2,13 @@
 <html>
 <head>
 	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
-	<title>{{.i18n.Tr "mail.reset_password.title" .DisplayName}}</title>
+	<meta name="format-detection" content="telephone=no,date=no,address=no,email=no,url=no"/>
+	<title>{{.i18n.Tr "mail.reset_password.title" (.DisplayName|DotEscape)}}</title>
 </head>
 
 {{ $recover_url := printf "%suser/recover_account?code=%s" AppUrl (QueryEscape .Code)}}
 <body>
-	<p>{{.i18n.Tr "mail.hi_user_x" .DisplayName | Str2html}}</p><br>
+	<p>{{.i18n.Tr "mail.hi_user_x" (.DisplayName|DotEscape) | Str2html}}</p><br>
 	<p>{{.i18n.Tr "mail.reset_password.text" .ResetPwdCodeLives | Str2html}}</p><p><a href="{{$recover_url}}">{{$recover_url}}</a></p><br>
 	<p>{{.i18n.Tr "mail.link_not_working_do_paste"}}</p>