feat: expose decode header utility

Author: tada5hi

packages/jsonwebtoken/index.js

@@ -351,3 +351,4 @@ module.exports.sign = nativeBinding.sign
 module.exports.signSync = nativeBinding.signSync
 module.exports.verify = nativeBinding.verify
 module.exports.verifySync = nativeBinding.verifySync
+module.exports.decodeHader = nativeBinding.decodeHader

packages/jsonwebtoken/src/decode.rs

@@ -0,0 +1,13 @@
+use napi::{bindgen_prelude::*};
+use napi_derive::napi;
+
+use crate::{header::Header};
+
+#[napi]
+pub fn decode_header(
+    token: &str
+) -> Header {
+    let result = jsonwebtoken::decode_header(&token);
+
+    let header = Header::from(result.unwrap());
+}

packages/jsonwebtoken/src/header.rs

@@ -73,6 +73,22 @@ impl From<&Header> for jsonwebtoken::Header {
   }
 }
 
+impl From<jsonwebtoken::Header> for Header {
+  #[inline]
+  fn from(value: &jsonwebtoken::Header) -> Header {
+    Header {
+      algorithm: value.alg.into(),
+      content_type: value.cty.clone(),
+      json_key_url: value.jku.clone(),
+      key_id: value.kid.clone(),
+      x5_url: value.x5u.clone(),
+      x5_cert_chain: value.x5c.clone(),
+      x5_cert_thumbprint: value.x5t.clone(),
+      x5t_s256_cert_thumbprint: value.x5t_s256.clone(),
+    }
+  }
+}
+
 impl Header {
   #[inline]
   pub fn merge(self, other: Self) -> Self {

packages/jsonwebtoken/src/lib.rs

@@ -3,16 +3,19 @@
 
 /// Explicit extern crate to use allocator.
 extern crate global_alloc;
+extern crate core;
 
 mod algorithm;
 mod claims;
+mod decode;
 mod header;
 mod sign;
 mod validation;
 mod verify;
 
 pub use algorithm::Algorithm;
 pub use claims::Claims;
+pub use decode::{decode_header};
 pub use header::Header;
 pub use sign::{sign, sign_sync};
 pub use validation::Validation;