add support for base64 decode/encode to rhai

NEXT_CHANGELOG.md

@@ -25,3 +25,11 @@ Description! And a link to a [reference](http://url)
 By [@USERNAME](https://github.com/USERNAME) in https://github.com/apollographql/router/pull/PULL_NUMBER
 -->
 
+## 🚀 Features
+
+### Add support for `base64encode()` / `base64decode()` in Rhai ([Issue #2025](https://github.com/apollographql/router/issues/2025))
+
+Two new functions, `base64encode()` and `base64decode()` may now be used to Base64-encode or Base64-decode strings, respectively.
+
+By [@garypen](https://github.com/garypen) in https://github.com/apollographql/router/pull/2394
+

apollo-router/src/plugins/rhai.rs

@@ -1500,6 +1500,14 @@ impl Rhai {
                 TraceId::maybe_new().ok_or_else(|| "trace unavailable".into())
             })
             .register_fn("to_string", |id: &mut TraceId| -> String { id.to_string() })
+            // Register basic "crypto" functions
+            // Base64 decode/encode
+            .register_fn("base64decode", |input: &mut ImmutableString| -> Result<String, Box<EvalAltResult>> {
+                String::from_utf8(base64::decode(input.as_bytes()).map_err(|e| e.to_string())?).map_err(|e| e.to_string().into())
+            })
+            .register_fn("base64encode", |input: &mut ImmutableString| -> String {
+                base64::encode(input.as_bytes())
+            })
             // Register a series of logging functions
             .register_fn("log_trace", |out: Dynamic| {
                 tracing::trace!(%out, "rhai_trace");
@@ -2096,6 +2104,24 @@ mod tests {
         assert_eq!(decoded, "This has an ümlaut in it.");
     }
 
+    #[test]
+    fn it_can_base64encode_string() {
+        let engine = Rhai::new_rhai_engine(None);
+        let encoded: String = engine
+            .eval(r#"base64encode("This has an ümlaut in it.")"#)
+            .expect("can encode string");
+        assert_eq!(encoded, "VGhpcyBoYXMgYW4gw7xtbGF1dCBpbiBpdC4=");
+    }
+
+    #[test]
+    fn it_can_base64decode_string() {
+        let engine = Rhai::new_rhai_engine(None);
+        let decoded: String = engine
+            .eval(r#"base64decode("VGhpcyBoYXMgYW4gw7xtbGF1dCBpbiBpdC4=")"#)
+            .expect("can decode string");
+        assert_eq!(decoded, "This has an ümlaut in it.");
+    }
+
     async fn base_process_function(fn_name: &str) -> Result<(), Box<rhai::EvalAltResult>> {
         let dyn_plugin: Box<dyn DynPlugin> = crate::plugin::plugins()
             .find(|factory| factory.name == "apollo.rhai")

docs/source/customizations/rhai-api.mdx

@@ -165,6 +165,27 @@ fn supergraph_service(service) {
 }
 ```
 
+## base64 encode/decode strings
+
+Your Rhai customization can use the functions `base64encode()` and `base64decode()` to encode/decode strings. `encode()` does not fail, but `decode()` can fail, so always handle exceptions when using the `decode()` function.
+
+```rhai
+fn supergraph_service(service) {
+    let original = "alice and bob";
+    let encoded = base64encode(original);
+    // encoded will be "YWxpY2UgYW5kIGJvYgo="
+    try {
+        let and_back = base64decode(encoded);
+        // and_back will be "alice and bob"
+    }
+    catch(err)
+    {
+        // log any errors
+        log_error(`base64decode error: ${err}`);
+    }
+}
+```
+
 ### Headers with multiple values
 
 The simple get/set api for dealing with single value headers is sufficient for most use cases. If you wish to set multiple values on a key then you should do this by supplying an array of values.