fix content validation, add unit test

Author: Mr-Leshiy

rust/signed_doc/src/content.rs

@@ -28,6 +28,7 @@ impl Content {
                 .decode(&data)
                 .map_err(|e| anyhow::anyhow!("Failed to decode {encoding} content: {e}"))?;
         }
+        content_type.validate(&data)?;
 
         Ok(Self {
             data,
@@ -44,18 +45,7 @@ impl Content {
     pub(crate) fn from_decoded(
         data: Vec<u8>, content_type: ContentType, content_encoding: Option<ContentEncoding>,
     ) -> anyhow::Result<Self> {
-        match content_type {
-            ContentType::Json => {
-                if let Err(e) = serde_json::to_value(&data) {
-                    anyhow::bail!("Invalid {content_type} content: {e}")
-                }
-            },
-            ContentType::Cbor => {
-                if let Err(e) = minicbor::decode::<minicbor::data::Token>(&data) {
-                    anyhow::bail!("Invalid {content_type} content: {e}")
-                }
-            },
-        }
+        content_type.validate(&data)?;
         Ok(Self {
             data,
             content_type,
@@ -97,13 +87,7 @@ impl Content {
 
     /// Return content byte size
     #[must_use]
-    pub fn len(&self) -> usize {
+    pub fn size(&self) -> usize {
         self.data.len()
     }
-
-    /// Return `true` if content is empty
-    #[must_use]
-    pub fn is_empty(&self) -> bool {
-        self.data.is_empty()
-    }
 }

rust/signed_doc/src/lib.rs

@@ -47,7 +47,7 @@ pub struct CatalystSignedDocument {
 impl Display for CatalystSignedDocument {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), std::fmt::Error> {
         writeln!(f, "{}", self.inner.metadata)?;
-        writeln!(f, "Payload Size: {} bytes", self.inner.content.len())?;
+        writeln!(f, "Payload Size: {} bytes", self.inner.content.size())?;
         writeln!(f, "Signature Information")?;
         if self.inner.signatures.is_empty() {
             writeln!(f, "  This document is unsigned.")?;

rust/signed_doc/src/metadata/content_type.rs

@@ -18,6 +18,25 @@ pub enum ContentType {
     Json,
 }
 
+impl ContentType {
+    /// Validates the provided `content` bytes to be a defined `ContentType`.
+    pub fn validate(self, content: &[u8]) -> anyhow::Result<()> {
+        match self {
+            Self::Json => {
+                if let Err(e) = serde_json::from_slice::<serde_json::Value>(content) {
+                    anyhow::bail!("Invalid {self} content: {e}")
+                }
+            },
+            Self::Cbor => {
+                if let Err(e) = minicbor::decode::<minicbor::data::Token>(content) {
+                    anyhow::bail!("Invalid {self} content: {e}")
+                }
+            },
+        }
+        Ok(())
+    }
+}
+
 impl Display for ContentType {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), std::fmt::Error> {
         match self {
@@ -78,3 +97,19 @@ impl TryFrom<&coset::ContentType> for ContentType {
         Ok(content_type)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn content_type_validate_test() {
+        let json_bytes = serde_json::to_vec(&serde_json::Value::Null).unwrap();
+        assert!(ContentType::Json.validate(&json_bytes).is_ok());
+        assert!(ContentType::Cbor.validate(&json_bytes).is_err());
+
+        let cbor_bytes = minicbor::to_vec(minicbor::data::Token::Null).unwrap();
+        assert!(ContentType::Json.validate(&cbor_bytes).is_err());
+        assert!(ContentType::Cbor.validate(&cbor_bytes).is_ok());
+    }
+}