refactor: simplify and reorganize Gateway

- use more concise types for ip/port to make cast to IP (and config creation in general) error-free.
- extract routes to dedicated function: this practice and naming as `app` a known idiom: this makes
for easier testing later on, and also will contain other configurations later on like banned IPs.
- Fix naming of arg in `add_transaction`: the arg is already
  deserialized from json, so no _json suffix.

crates/gateway/src/errors.rs

@@ -2,8 +2,6 @@ use thiserror::Error;
 
 #[derive(Debug, Error)]
 pub enum GatewayError {
-    #[error(transparent)]
-    ConfigError(#[from] GatewayConfigError),
     #[error(transparent)]
     HTTPError(#[from] hyper::http::Error),
     #[error("Internal server error")]
@@ -13,9 +11,3 @@ pub enum GatewayError {
     #[error("Error while starting the server")]
     ServerStartError(#[from] hyper::Error),
 }
-
-#[derive(Debug, Error)]
-pub enum GatewayConfigError {
-    #[error("Server address is not an bind IP address: {0}")]
-    InvalidServerBindAddress(String),
-}

crates/gateway/src/gateway.rs

@@ -1,10 +1,9 @@
-use crate::errors::{GatewayConfigError, GatewayError};
+use crate::errors::GatewayError;
 use axum::response::IntoResponse;
 use axum::routing::{get, post};
 use axum::{Json, Router};
 use starknet_api::external_transaction::ExternalTransaction;
-use std::net::SocketAddr;
-use std::str::FromStr;
+use std::net::{IpAddr, SocketAddr};
 
 #[cfg(test)]
 #[path = "gateway_test.rs"]
@@ -13,20 +12,14 @@ pub mod gateway_test;
 pub type GatewayResult = Result<(), GatewayError>;
 
 pub struct Gateway {
-    pub gateway_config: GatewayConfig,
+    pub config: GatewayConfig,
 }
 
 impl Gateway {
-    pub async fn build_server(&self) -> GatewayResult {
+    pub async fn build_server(self) -> GatewayResult {
         // Parses the bind address from GatewayConfig, returning an error for invalid addresses.
-        let addr = SocketAddr::from_str(&self.gateway_config.bind_address).map_err(|_| {
-            GatewayConfigError::InvalidServerBindAddress(self.gateway_config.bind_address.clone())
-        })?;
-
-        // Sets up the router with the specified routes for the server.
-        let app = Router::new()
-            .route("/is_alive", get(is_alive))
-            .route("/add_transaction", post(add_transaction));
+        let addr = SocketAddr::new(self.config.ip, self.config.port);
+        let app = app();
 
         // Create a server that runs forever.
         axum::Server::bind(&addr)
@@ -38,18 +31,34 @@ impl Gateway {
     }
 }
 
-pub struct GatewayConfig {
-    pub bind_address: String,
+/// Sets up the router with the specified routes for the server.
+pub fn app() -> Router {
+    Router::new()
+        .route("/is_alive", get(is_alive))
+        .route("/add_transaction", post(add_transaction))
+    // TODO: when we need to configure the router, like adding banned ips, add it here via
+    // `with_state`.
 }
 
 async fn is_alive() -> impl IntoResponse {
     unimplemented!("Future handling should be implemented here.");
 }
 
-async fn add_transaction(Json(transaction_json): Json<ExternalTransaction>) -> impl IntoResponse {
-    match transaction_json {
+async fn add_transaction(Json(transaction): Json<ExternalTransaction>) -> impl IntoResponse {
+    match transaction {
         ExternalTransaction::Declare(_) => "DECLARE",
         ExternalTransaction::DeployAccount(_) => "DEPLOY_ACCOUNT",
         ExternalTransaction::Invoke(_) => "INVOKE",
     }
 }
+
+pub struct GatewayConfig {
+    pub ip: IpAddr,
+    pub port: u16,
+}
+
+impl GatewayConfig {
+    pub fn new(ip: IpAddr, port: u16) -> Self {
+        Self { ip, port }
+    }
+}