fix: sha-256 parsing

Author: KrLite

src/env.rs

@@ -5,6 +5,8 @@ use std::{env, path::PathBuf};
 use api_framework::{parse_env, static_lazy_lock};
 use tracing::level_filters::LevelFilter;
 
+use crate::sha256::sha256_hex_to_bytes;
+
 /// Sets up environment variables from `.env` and `{crate_name}.env`.
 pub fn setup() {
     dotenvy::dotenv().ok();
@@ -61,10 +63,10 @@ static_lazy_lock! {
 
 static_lazy_lock! {
     /// The PASETO symmetric key hashed using SHA256.
-    pub PASETO_SYMMETRIC_KEY: [u8; 32] = parse_env!("PASETO_SYMMETRIC_KEY" => |k| Ok::<[u8; 32], _>(k.as_bytes().try_into().expect("PASETO_SYMMETRIC_KEY must be 32 bytes long"))).expect("PASETO_SYMMETRIC_KEY not set in environment");
+    pub PASETO_SYMMETRIC_KEY: [u8; 32] = parse_env!("PASETO_SYMMETRIC_KEY" => |k| Ok(sha256_hex_to_bytes(&k).expect("PASETO_SYMMETRIC_KEY must be a valid 32-byte long SHA256 token"))).expect("PASETO_SYMMETRIC_KEY not set in environment");
 }
 
 static_lazy_lock! {
     /// The session symmetric key hashed using SHA256.
-    pub SESSION_SYMMETRIC_KEY: [u8; 32] = parse_env!("SESSION_SYMMETRIC_KEY" => |k| Ok::<[u8; 32], _>(k.as_bytes().try_into().expect("SESSION_SYMMETRIC_KEY must be 32 bytes long"))).expect("SESSION_SYMMETRIC_KEY not set in environment");
+    pub SESSION_SYMMETRIC_KEY: [u8; 32] = parse_env!("SESSION_SYMMETRIC_KEY" => |k| Ok(sha256_hex_to_bytes(&k).expect("SESSION_SYMMETRIC_KEY must be a valid 32-byte long SHA256 token"))).expect("SESSION_SYMMETRIC_KEY not set in environment");
 }

src/main.rs

@@ -14,6 +14,7 @@ use tokio::net::TcpListener;
 
 pub mod config;
 pub mod env;
+pub mod sha256;
 pub mod trace;
 
 pub mod database;

src/sha256.rs

@@ -0,0 +1,43 @@
+//! Utilities for handling SHA-256 hashes.
+
+/// Converts a SHA-256 hash in hexadecimal string format to a byte array.
+#[derive(Debug)]
+#[non_exhaustive]
+pub enum HexDecodeError {
+    /// The provided hex string does not have the correct length.
+    InvalidLength,
+    /// The provided hex string contains invalid characters.
+    InvalidHexCharacter,
+}
+
+/// Converts a SHA-256 hash in hexadecimal string format to a byte array.
+///
+/// # Errors
+///
+/// Returns [`HexDecodeError`] if the input string is not a valid SHA-256 hex string.
+pub fn sha256_hex_to_bytes(hex: &str) -> Result<[u8; 32], HexDecodeError> {
+    if hex.len() != 64 {
+        return Err(HexDecodeError::InvalidLength);
+    }
+
+    let mut out = [0u8; 32];
+    let bytes = hex.as_bytes();
+
+    for i in 0..32 {
+        let hi = from_hex(bytes[i * 2])?;
+        let lo = from_hex(bytes[i * 2 + 1])?;
+        out[i] = (hi << 4) | lo;
+    }
+
+    Ok(out)
+}
+
+#[inline]
+fn from_hex(b: u8) -> Result<u8, HexDecodeError> {
+    match b {
+        b'0'..=b'9' => Ok(b - b'0'),
+        b'a'..=b'f' => Ok(b - b'a' + 10),
+        b'A'..=b'F' => Ok(b - b'A' + 10),
+        _ => Err(HexDecodeError::InvalidHexCharacter),
+    }
+}