Move the VAPID public key encoding into a serde-compatible encoding module.

The [Serde attribute docs][serde-attr] don't spell out that this will work, but experimentally, it looks like a module used with `#[serde(with)]` only needs to have the `encode`/`decode` functions if they're actually used, and can be "incomplete" if the missing ones are also unused in your code. That's the case here: we serialize VAPID keys, but never deserialize them.

[serde-attr]: https://serde.rs/field-attrs.html#with

This improves organization a bit in my view, but more importantly it also sets us up for a coming change where we _will_ start deserializing VAPID keys, and where I'd like to use the same logic: giving it its own module will make that easier to organize.

1 files changed, 1 insertions, 12 deletions

diff --git a/src/vapid/event.rs b/src/vapid/event.rs
index af70ac2..cf3be77 100644
--- a/src/vapid/event.rs
+++ b/src/vapid/event.rs
@@ -1,6 +1,4 @@
-use base64::{Engine, engine::general_purpose::URL_SAFE};
 use p256::ecdsa::VerifyingKey;
-use serde::Serialize;
 
 use crate::event::{Instant, Sequenced};
 
@@ -22,7 +20,7 @@ impl Sequenced for Event {
 pub struct Changed {
     #[serde(flatten)]
     pub instant: Instant,
-    #[serde(serialize_with = "as_vapid_key")]
+    #[serde(with = "crate::vapid::ser::key")]
     pub key: VerifyingKey,
 }
 
@@ -37,12 +35,3 @@ impl Sequenced for Changed {
         self.instant
     }
 }
-
-fn as_vapid_key<S>(key: &VerifyingKey, serializer: S) -> Result<S::Ok, S::Error>
-where
-    S: serde::Serializer,
-{
-    let key = key.to_sec1_bytes();
-    let key = URL_SAFE.encode(key);
-    key.serialize(serializer)
-}