Add an Explicit Message Encryption parser.

src/eme.rs

@@ -0,0 +1,68 @@
+use minidom::Element;
+
+use error::Error;
+
+use ns;
+
+#[derive(Debug, Clone)]
+pub struct ExplicitMessageEncryption {
+    pub namespace: String,
+    pub name: Option<String>,
+}
+
+pub fn parse_explicit_message_encryption(root: &Element) -> Result<ExplicitMessageEncryption, Error> {
+    if !root.is("encryption", ns::EME) {
+        return Err(Error::ParseError("This is not an encryption element."));
+    }
+    for _ in root.children() {
+        return Err(Error::ParseError("Unknown child in encryption element."));
+    }
+    let namespace = root.attr("namespace").ok_or(Error::ParseError("Mandatory argument 'namespace' not present in encryption element."))?.to_owned();
+    let name = root.attr("name").and_then(|value| value.parse().ok());
+    Ok(ExplicitMessageEncryption {
+        namespace: namespace,
+        name: name,
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use minidom::Element;
+    use error::Error;
+    use eme;
+
+    #[test]
+    fn test_simple() {
+        let elem: Element = "<encryption xmlns='urn:xmpp:eme:0' namespace='urn:xmpp:otr:0'/>".parse().unwrap();
+        let encryption = eme::parse_explicit_message_encryption(&elem).unwrap();
+        assert_eq!(encryption.namespace, "urn:xmpp:otr:0");
+        assert_eq!(encryption.name, None);
+
+        let elem: Element = "<encryption xmlns='urn:xmpp:eme:0' namespace='some.unknown.mechanism' name='SuperMechanism'/>".parse().unwrap();
+        let encryption = eme::parse_explicit_message_encryption(&elem).unwrap();
+        assert_eq!(encryption.namespace, "some.unknown.mechanism");
+        assert_eq!(encryption.name, Some(String::from("SuperMechanism")));
+    }
+
+    #[test]
+    fn test_unknown() {
+        let elem: Element = "<replace xmlns='urn:xmpp:message-correct:0'/>".parse().unwrap();
+        let error = eme::parse_explicit_message_encryption(&elem).unwrap_err();
+        let message = match error {
+            Error::ParseError(string) => string,
+            _ => panic!(),
+        };
+        assert_eq!(message, "This is not an encryption element.");
+    }
+
+    #[test]
+    fn test_invalid_child() {
+        let elem: Element = "<encryption xmlns='urn:xmpp:eme:0'><coucou/></encryption>".parse().unwrap();
+        let error = eme::parse_explicit_message_encryption(&elem).unwrap_err();
+        let message = match error {
+            Error::ParseError(string) => string,
+            _ => panic!(),
+        };
+        assert_eq!(message, "Unknown child in encryption element.");
+    }
+}