Convert email domains to punycode

Cargo.toml

@@ -111,6 +111,8 @@ openssl = "0.10.26"
 
 # URL encoding library
 percent-encoding = "2.1.0"
+# Punycode conversion
+idna = "0.2.0"
 
 [patch.crates-io]
 # Use newest ring

src/api/core/two_factor/email.rs

@@ -271,7 +271,7 @@ impl EmailTokenData {
 
 /// Takes an email address and obscures it by replacing it with asterisks except two characters.
 pub fn obscure_email(email: &str) -> String {
-    let split: Vec<&str> = email.split('@').collect();
+    let split: Vec<&str> = email.rsplitn(2, '@').collect();
 
     let mut name = split[0].to_string();
     let domain = &split[1];

src/mail.rs

@@ -259,6 +259,18 @@ pub fn send_change_email(address: &str, token: &str) -> EmptyResult {
 }
 
 fn send_email(address: &str, subject: &str, body_html: &str, body_text: &str) -> EmptyResult {
+    let address_split: Vec<&str> = address.rsplitn(2, '@').collect();
+    if address_split.len() != 2 {
+        err!("Invalid email address (no @)");
+    }
+
+    let domain_puny = match idna::domain_to_ascii_strict(address_split[1]) {
+        Ok(d) => d,
+        Err(_) => err!("Can't convert email domain to ASCII representation"),
+    };
+
+    let address = format!("{}@{}", address_split[0], domain_puny);
+
     let html = PartBuilder::new()
         .body(encode_to_str(body_html))
         .header(("Content-Type", "text/html; charset=utf-8"))