Add a hash parser.

src/hashes.rs

@@ -0,0 +1,66 @@
+use minidom::Element;
+
+use error::Error;
+
+use ns;
+
+#[derive(Debug, Clone)]
+pub struct Hash {
+    pub algo: String,
+    pub hash: String,
+}
+
+pub fn parse_hash(root: &Element) -> Result<Hash, Error> {
+    if !root.is("hash", ns::HASHES) {
+        return Err(Error::ParseError("This is not a hash element."));
+    }
+    for _ in root.children() {
+        return Err(Error::ParseError("Unknown child in hash element."));
+    }
+    let algo = root.attr("algo").ok_or(Error::ParseError("Mandatory argument 'algo' not present in hash element."))?.to_owned();
+    let hash = match root.text().as_ref() {
+        "" => return Err(Error::ParseError("Hash element shouldn’t be empty.")),
+        text => text.to_owned(),
+    };
+    Ok(Hash {
+        algo: algo,
+        hash: hash,
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use minidom::Element;
+    use error::Error;
+    use hashes;
+
+    #[test]
+    fn test_simple() {
+        let elem: Element = "<hash xmlns='urn:xmpp:hashes:2' algo='sha-256'>2XarmwTlNxDAMkvymloX3S5+VbylNrJt/l5QyPa+YoU=</hash>".parse().unwrap();
+        let hash = hashes::parse_hash(&elem).unwrap();
+        assert_eq!(hash.algo, "sha-256");
+        assert_eq!(hash.hash, "2XarmwTlNxDAMkvymloX3S5+VbylNrJt/l5QyPa+YoU=");
+    }
+
+    #[test]
+    fn test_unknown() {
+        let elem: Element = "<replace xmlns='urn:xmpp:message-correct:0'/>".parse().unwrap();
+        let error = hashes::parse_hash(&elem).unwrap_err();
+        let message = match error {
+            Error::ParseError(string) => string,
+            _ => panic!(),
+        };
+        assert_eq!(message, "This is not a hash element.");
+    }
+
+    #[test]
+    fn test_invalid_child() {
+        let elem: Element = "<hash xmlns='urn:xmpp:hashes:2'><coucou/></hash>".parse().unwrap();
+        let error = hashes::parse_hash(&elem).unwrap_err();
+        let message = match error {
+            Error::ParseError(string) => string,
+            _ => panic!(),
+        };
+        assert_eq!(message, "Unknown child in hash element.");
+    }
+}

src/lib.rs

@@ -49,6 +49,9 @@ pub mod media_element;
 /// XEP-0224: Attention
 pub mod attention;
 
+/// XEP-0300: Use of Cryptographic Hash Functions in XMPP
+pub mod hashes;
+
 /// XEP-0308: Last Message Correction
 pub mod message_correct;
 

src/ns.rs

@@ -31,6 +31,9 @@ pub const MEDIA_ELEMENT: &'static str = "urn:xmpp:media-element";
 /// XEP-0224: Attention
 pub const ATTENTION: &'static str = "urn:xmpp:attention:0";
 
+/// XEP-0300: Use of Cryptographic Hash Functions in XMPP
+pub const HASHES: &'static str = "urn:xmpp:hashes:2";
+
 /// XEP-0308: Last Message Correction
 pub const MESSAGE_CORRECT: &'static str = "urn:xmpp:message-correct:0";