Add is_json function

docs/_docs/user-guide/eldritch.md

@@ -242,16 +242,21 @@ crypto.from_json("{\"foo\":\"bar\"}")
 }
 ```
 
-### crypto.hash_file
+### crypto.is_json
 
-`crypto.hash_file(file: str, algo: str) -> str`
+`crypto.is_json(content: str) -> bool`
 
-The <b>crypto.hash_file</b> method will produce the hash of the given file's contents. Valid algorithms include:
+The <b>crypto.is_json</b> tests if JSON is valid.
 
-- MD5
-- SHA1
-- SHA256
-- SHA512
+```python
+crypto.is_json("{\"foo\":\"bar\"}")
+True
+```
+
+```python
+crypto.is_json("foobar")
+False
+```
 
 ### crypto.to_json
 
@@ -264,6 +269,17 @@ crypto.to_json({"foo": "bar"})
 "{\"foo\":\"bar\"}"
 ```
 
+### crypto.hash_file
+
+`crypto.hash_file(file: str, algo: str) -> str`
+
+The <b>crypto.hash_file</b> method will produce the hash of the given file's contents. Valid algorithms include:
+
+- MD5
+- SHA1
+- SHA256
+- SHA512
+
 ---
 
 ## File

implants/lib/eldritch/src/crypto/is_json_impl.rs

@@ -0,0 +1,32 @@
+use anyhow::Result;
+
+pub fn is_json(json: String) -> Result<bool> {
+    match serde_json::from_str::<serde_json::Value>(&json) {
+        Ok(_) => Ok(true),
+        Err(_) => Ok(false),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_from_json_object() -> anyhow::Result<()> {
+        let res = super::is_json(r#"{"test": "test"}"#.to_string())?;
+        assert!(res);
+        Ok(())
+    }
+
+    #[test]
+    fn test_from_json_list() -> anyhow::Result<()> {
+        let res = super::is_json(r#"[1, "foo", false, null]"#.to_string())?;
+        assert!(res);
+        Ok(())
+    }
+
+    #[test]
+    fn test_from_json_invalid() -> anyhow::Result<()> {
+        let res = super::is_json(r#"{"test":"#.to_string())?;
+        assert!(!res);
+        Ok(())
+    }
+}

implants/lib/eldritch/src/crypto/mod.rs

@@ -4,6 +4,7 @@ mod decode_b64_impl;
 mod encode_b64_impl;
 mod from_json_impl;
 mod hash_file_impl;
+mod is_json_impl;
 mod to_json_impl;
 
 use starlark::environment::MethodsBuilder;
@@ -52,6 +53,12 @@ fn methods(builder: &mut MethodsBuilder) {
         decode_b64_impl::decode_b64(content, encode_type)
     }
 
+    #[allow(unused_variables)]
+    fn is_json<'v>(this: &CryptoLibrary, starlark_heap: &'v Heap, content: String) -> anyhow::Result<bool> {
+        is_json_impl::is_json(content)
+    }
+
+
     #[allow(unused_variables)]
     fn from_json<'v>(this: &CryptoLibrary, starlark_heap: &'v Heap, content: String) -> anyhow::Result<Value<'v>> {
         from_json_impl::from_json(starlark_heap, content)

implants/lib/eldritch/src/runtime/mod.rs

@@ -144,7 +144,7 @@ mod tests {
                 parameters: HashMap::new(),
                 file_names: Vec::new(),
             },
-            want_text: format!("{}\n", r#"["aes_decrypt_file", "aes_encrypt_file", "decode_b64", "encode_b64", "from_json", "hash_file", "to_json"]"#),
+            want_text: format!("{}\n", r#"["aes_decrypt_file", "aes_encrypt_file", "decode_b64", "encode_b64", "from_json", "hash_file", "is_json", "to_json"]"#),
             want_error: None,
         },
         time_bindings: TestCase {