From 1eb5cda03367c66b7a52faae485129cd56deb87c Mon Sep 17 00:00:00 2001
From: alemi <me@alemi.dev>
Date: Mon, 15 Jul 2024 02:57:32 +0200
Subject: [PATCH] feat: add cloaker trait

---
 upub/core/Cargo.toml          |  4 +++-
 upub/core/src/traits/cloak.rs | 37 +++++++++++++++++++++++++++++++++++
 upub/core/src/traits/mod.rs   |  2 ++
 3 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 upub/core/src/traits/cloak.rs

diff --git a/upub/core/Cargo.toml b/upub/core/Cargo.toml
index ec61028..6b6eff4 100644
--- a/upub/core/Cargo.toml
+++ b/upub/core/Cargo.toml
@@ -14,7 +14,9 @@ readme = "README.md"
 thiserror = "1"
 async-recursion = "1.1"
 async-trait = "0.1"
-sha256 = "1.5"
+sha256 = "1.5" # TODO get rid of this and use directly sha2!!
+sha2 = "0.10"
+hmac = "0.12"
 openssl = "0.10" # TODO handle pubkeys with a smaller crate
 base64 = "0.22"
 chrono = { version = "0.4", features = ["serde"] }
diff --git a/upub/core/src/traits/cloak.rs b/upub/core/src/traits/cloak.rs
new file mode 100644
index 0000000..1856c52
--- /dev/null
+++ b/upub/core/src/traits/cloak.rs
@@ -0,0 +1,37 @@
+use base64::{Engine, prelude::BASE64_URL_SAFE};
+use hmac::Mac;
+
+
+pub type Signature = hmac::Hmac<sha2::Sha256>;
+
+pub trait Cloaker {
+	fn secret(&self) -> &str;
+
+	fn cloak(&self, url: &str) -> (String, String) {
+		let mut hmac = Signature::new_from_slice(self.secret().as_bytes())
+			.expect("invalid length for hmac key, cannot cloak");
+		hmac.update(url.as_bytes());
+		let sig = BASE64_URL_SAFE.encode(hmac.finalize().into_bytes());
+		let url = BASE64_URL_SAFE.encode(url);
+		(sig, url)
+	}
+
+	fn uncloak(&self, signature: &str, url: &str) -> Option<String> {
+		let mut hmac = Signature::new_from_slice(self.secret().as_bytes())
+			.expect("invalid length for hmac key, cannot cloak");
+
+		let sig = BASE64_URL_SAFE.decode(signature).ok()?;
+		let url = std::str::from_utf8(&BASE64_URL_SAFE.decode(url).ok()?).ok()?.to_string();
+
+		hmac.update(url.as_bytes());
+		hmac.verify_slice(&sig).ok()?;
+
+		Some(url)
+	}
+}
+
+impl Cloaker for crate::Context {
+	fn secret(&self) -> &str {
+		&self.cfg().security.proxy_secret
+	}
+}
diff --git a/upub/core/src/traits/mod.rs b/upub/core/src/traits/mod.rs
index e2229a6..d4b711b 100644
--- a/upub/core/src/traits/mod.rs
+++ b/upub/core/src/traits/mod.rs
@@ -3,9 +3,11 @@ pub mod fetch;
 pub mod normalize;
 pub mod process;
 pub mod admin;
+pub mod cloak;
 
 pub use admin::Administrable;
 pub use address::Addresser;
 pub use normalize::Normalizer;
 pub use process::Processor;
 pub use fetch::Fetcher;
+pub use cloak::Cloaker;