From d588e9751bac8d9c1bf74004bb1d96eaa30fe28c Mon Sep 17 00:00:00 2001
From: refcell <abigger87@gmail.com>
Date: Sun, 25 Aug 2024 13:58:59 -0400
Subject: [PATCH] feat(p2p): P2P Crate (#27)

### Description

Sets up a `p2p` crate for `hera` based off of
https://github.com/paradigmxyz/reth-exex-examples/pull/15.

### Metadata

Makes progress on https://github.com/paradigmxyz/op-rs/issues/6
---
 Cargo.lock              |  8 ++++++
 Cargo.toml              |  1 +
 crates/p2p/Cargo.toml   | 16 ++++++++++++
 crates/p2p/src/lib.rs   | 10 +++++++
 crates/p2p/src/types.rs | 58 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 93 insertions(+)
 create mode 100644 crates/p2p/Cargo.toml
 create mode 100644 crates/p2p/src/lib.rs
 create mode 100644 crates/p2p/src/types.rs

diff --git a/Cargo.lock b/Cargo.lock
index f8b61f9..f858b68 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4293,6 +4293,14 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
 
+[[package]]
+name = "p2p"
+version = "0.0.0"
+dependencies = [
+ "alloy",
+ "kona-primitives",
+]
+
 [[package]]
 name = "page_size"
 version = "0.6.0"
diff --git a/Cargo.toml b/Cargo.toml
index 90c9c14..bee5586 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,6 +11,7 @@ categories = ["cryptography", "cryptography::cryptocurrencies"]
 [workspace]
 members = [
   "bin/hera",
+  "crates/p2p",
   "crates/kona-providers",
   "crates/ser",
 ]
diff --git a/crates/p2p/Cargo.toml b/crates/p2p/Cargo.toml
new file mode 100644
index 0000000..72c1a07
--- /dev/null
+++ b/crates/p2p/Cargo.toml
@@ -0,0 +1,16 @@
+[package]
+name = "p2p"
+description = "Consensus P2P Stack for L2"
+version = "0.0.0"
+edition.workspace = true
+authors.workspace = true
+license.workspace = true
+keywords.workspace = true
+repository.workspace = true
+categories.workspace = true
+rust-version.workspace = true
+
+[dependencies]
+alloy.workspace = true
+
+kona-primitives = { git = "https://github.com/ethereum-optimism/kona", default-features = true }
diff --git a/crates/p2p/src/lib.rs b/crates/p2p/src/lib.rs
new file mode 100644
index 0000000..93d7aa6
--- /dev/null
+++ b/crates/p2p/src/lib.rs
@@ -0,0 +1,10 @@
+//! Consensus P2P Stack
+
+#![doc(issue_tracker_base_url = "https://github.com/paradigmxyz/op-rs/issues/")]
+#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
+#![cfg_attr(not(test), warn(unused_crate_dependencies))]
+#![cfg_attr(not(test), no_std)]
+
+extern crate alloc;
+
+pub mod types;
diff --git a/crates/p2p/src/types.rs b/crates/p2p/src/types.rs
new file mode 100644
index 0000000..e7f939a
--- /dev/null
+++ b/crates/p2p/src/types.rs
@@ -0,0 +1,58 @@
+//! Types for the P2P network.
+
+use alloc::vec::Vec;
+use alloy::primitives::{keccak256, Signature, B256};
+use kona_primitives::L2ExecutionPayload;
+
+/// An envelope around the execution payload for L2.
+#[derive(Debug)]
+pub struct ExecutionPayloadEnvelope {
+    /// The execution payload.
+    pub payload: L2ExecutionPayload,
+    /// A signature for the payload.
+    pub signature: Signature,
+    /// The hash of the payload.
+    pub hash: PayloadHash,
+    /// The parent beacon block root.
+    pub parent_beacon_block_root: Option<B256>,
+}
+
+/// Represents the Keccak256 hash of the block
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct PayloadHash(B256);
+
+impl From<&[u8]> for PayloadHash {
+    /// Returns the Keccak256 hash of a sequence of bytes
+    fn from(value: &[u8]) -> Self {
+        Self(keccak256(value))
+    }
+}
+
+impl PayloadHash {
+    /// The expected message that should be signed by the unsafe block signer.
+    pub fn signature_message(&self, chain_id: u64) -> B256 {
+        let domain = B256::ZERO;
+        let chain_id = B256::left_padding_from(&chain_id.to_be_bytes()[..]);
+        let payload_hash = self.0;
+
+        let data: Vec<u8> =
+            [domain.as_slice(), chain_id.as_slice(), payload_hash.as_slice()].concat();
+
+        keccak256(data)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use alloy::primitives::b256;
+
+    #[test]
+    fn test_signature_message() {
+        let inner = b256!("9999999999999999999999999999999999999999999999999999999999999999");
+        let hash = PayloadHash::from(inner.as_slice());
+        let chain_id = 10;
+        let expected = b256!("44a0e2b1aba1aae1771eddae1dcd2ad18a8cdac8891517153f03253e49d3f206");
+        assert_eq!(hash.signature_message(chain_id), expected);
+    }
+}