Refactor board creation code

Cargo.lock

@@ -150,6 +150,7 @@ dependencies = [
  "log",
  "pretty_env_logger",
  "r2d2",
+ "rand",
  "redis",
  "serde",
  "serde_json",

Cargo.toml

@@ -14,4 +14,5 @@ lazy_static = { version = "1.4.0" }
 serde = { version = "1.0.147", features=["derive"] }
 serde_json = { version = "1.0.87" }
 log = { version = "0.4.17" }
-pretty_env_logger = { version = "0.4.0" }
+pretty_env_logger = { version = "0.4.0" }
+rand = { version = "0.8.5" }

src/config.rs

@@ -11,4 +11,7 @@ lazy_static! {
         .expect("AXUM_HOST_STRING to be set")
         .parse()
         .expect("AXUM_HOST_STRING to be a valid SocketAddr");
+
+    pub static ref CREATE_TOKEN: String = env::var("CREATE_TOKEN")
+        .expect("CREATE_TOKEN to be set");
 }

src/main.rs

@@ -1,5 +1,6 @@
 mod config;
 mod routes;
+mod outcome;
 
 use axum::routing::{get, post};
 

src/outcome.rs

@@ -0,0 +1,65 @@
+use axum::extract::Json;
+use axum::http::StatusCode;
+use serde_json::Value;
+
+/// The `([StatusCode], Body)` tuple returned by API handlers.
+pub(crate) type RequestTuple = (StatusCode, Json<Value>);
+
+/// A [`Result`] made of two [`RequestTuple`]s to make handling errors easier.
+pub(crate) type RequestResult = Result<RequestTuple, RequestTuple>;
+
+macro_rules! req_error {
+    ( $val:tt ) => {
+        Json(serde_json::json!({
+            "ok": false, 
+            "error": $val
+        }))
+    };
+}
+
+/// Macro used to build a API error.
+pub(crate) use req_error;
+
+macro_rules! req_success {
+    ( $val:tt ) => {
+        Json(serde_json::json!({
+            "ok": true,
+            "data": $val
+        }))
+    }
+}
+
+/// Macro used to build a API success.
+pub(crate) use req_success;
+
+/// The server could not connect to Redis.
+pub(crate) fn redis_conn_failed(_err: redis::RedisError) -> RequestTuple {
+    (
+        StatusCode::GATEWAY_TIMEOUT, 
+        req_error!("Could not connect to Redis")
+    )
+}
+
+/// The execution of a command in Redis failed.
+pub(crate) fn redis_cmd_failed(_err: redis::RedisError) -> RequestTuple {
+    (
+        StatusCode::BAD_GATEWAY, 
+        req_error!("Could not execute Redis command")
+    )
+}
+
+/// The result of a command in Redis is unexpected.
+pub(crate) fn redis_unexpected_behaviour() -> RequestTuple {
+    (
+        StatusCode::INTERNAL_SERVER_ERROR, 
+        req_error!("Redis gave an unexpected response")
+    )
+}
+
+/// The request succeeded, and there's no data to be returned.
+pub(crate) fn success_null() -> RequestTuple {
+    (
+        StatusCode::OK, 
+        req_success!(null)
+    )
+}

src/routes/board.rs

@@ -1,62 +1,72 @@
 //! Module defining routes for `/board/`.
 
-use axum::{Extension, Json};
 use axum::http::StatusCode;
-use axum::response::{IntoResponse, Response};
+use axum::extract::{Extension, Json};
 use redis::AsyncCommands;
-use serde_json::json;
 use serde::Serialize;
 use serde::Deserialize;
-
-
-/// Possible results for `POST /board/`.
-pub enum OutcomeBoardPost {
-    /// Could not connect to Redis.
-    RedisConnectionError,
-    /// Could not check the existence of the board on Redis.
-    RedisCheckExistenceError,
-    /// Could not set the board ordering on Redis.
-    RedisSetOrderError,
-    /// Board already exists.
-    AlreadyExists,
-    /// Board created successfully.
-    Success,
-}
-
-use OutcomeBoardPost::*;
-
-impl IntoResponse for OutcomeBoardPost {
-    fn into_response(self) -> Response {
-        let (status, response) = match self {
-            RedisConnectionError => (StatusCode::GATEWAY_TIMEOUT, json!("Could not connect to Redis")),
-            RedisCheckExistenceError => (StatusCode::INTERNAL_SERVER_ERROR, json!("Could not check if the board already exists")),
-            RedisSetOrderError => (StatusCode::INTERNAL_SERVER_ERROR, json!("Could not set the board's ordering")),
-            AlreadyExists => (StatusCode::CONFLICT, json!("Board already exists")),
-            Success => (StatusCode::OK, json!([]))
-        };
-
-        IntoResponse::into_response((status, Json(response)))
-    }
-}
+use crate::outcome;
 
 
 #[derive(Copy, Clone, Debug, Serialize, Deserialize)]
 pub enum Order {
     /// The greater the score, the worse it is.
+    #[serde(rename = "ASC")]
     Ascending,
     /// The greater the score, the better it is.
+    #[serde(rename = "DSC")]
     Descending,
 }
 
+impl From<Order> for String {
+    fn from(ord: Order) -> Self {
+        match ord {
+            Order::Ascending  => "ASC".to_string(),
+            Order::Descending => "DSC".to_string(),
+        }
+    }
+}
+
 
 /// Expected input data for `POST /board/`.
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct RouteBoardPostInput {
+    /// The name of the board to create.
     name: String,
+    /// The [`Order`] of the scores in the board to create.
     order: Order,
 }
 
 
+/// Expected output data for `POST /board/`.
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct RouteBoardPostOutput {
+    /// The name of the created board.
+    name: String,
+    /// The [`Order`] of the scores in the created board.
+    order: Order,
+    /// The token to use to submit scores to the board.
+    token: String,
+}
+
+
+async fn ensure_key_is_empty(rconn: &mut redis::aio::Connection, key: &str) -> Result<(), outcome::RequestTuple> {
+    log::trace!("Ensuring that the Redis key `{key}` does not contain anything...");
+
+    redis::cmd("TYPE").arg(&key)
+        .query_async::<redis::aio::Connection, String>(rconn).await
+        .map_err(outcome::redis_cmd_failed)?
+        .eq("none")
+        .then_some(())
+        .ok_or((StatusCode::CONFLICT, outcome::req_error!("Board already exists")))
+}
+
+
+const TOKEN_CHARS: &[char; 62] = &[
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'
+];
+
+
 /// Handler for `POST /board/`.
 ///
 /// Creates a new board, storing the details on Redis.
@@ -64,38 +74,55 @@ pub struct RouteBoardPostInput {
 /// Will refuse to overwrite an already existing board.
 pub async fn route_board_post(
     Extension(rclient): Extension<redis::Client>,
-    Json(input): Json<RouteBoardPostInput>,
-) -> Result<OutcomeBoardPost, OutcomeBoardPost> {
+    Json(RouteBoardPostInput {name, order}): Json<RouteBoardPostInput>,
+) -> outcome::RequestResult {
 
     log::trace!("Connecting to Redis...");
     let mut rconn = rclient.get_async_connection().await
-        .map_err(|_| RedisConnectionError)?;
+        .map_err(outcome::redis_conn_failed)?;
 
-    let name = &input.name;
+    log::trace!("Determining the Redis key names...");
     let order_key = format!("board:{name}:order");
+    let token_key = format!("board:{name}:token");
     let scores_key = format!("board:{name}:scores");
 
-    log::trace!("Checking that the board does not already exist via the order key...");
-    redis::cmd("TYPE").arg(&order_key).query_async::<redis::aio::Connection, String>(&mut rconn).await
-        .map_err(|_| RedisCheckExistenceError)?
-        .eq("none").then_some(())
-        .ok_or(AlreadyExists)?;
+    log::trace!("Ensuring a board does not already exist...");
+    ensure_key_is_empty(&mut rconn, &order_key).await?;
+    ensure_key_is_empty(&mut rconn, &token_key).await?;
+    ensure_key_is_empty(&mut rconn, &scores_key).await?;
 
-    // Possibly superfluous, but better be safe than sorry
-    log::trace!("Checking that the board does not already exist via the scores key...");
-    redis::cmd("TYPE").arg(&scores_key).query_async::<redis::aio::Connection, String>(&mut rconn).await
-        .map_err(|_| RedisCheckExistenceError)?
-        .eq("none").then_some(())
-        .ok_or(AlreadyExists)?;
+    log::info!("Creating board: {name:?}");
 
-    log::info!("Creating board: {}", &name);
+    log::trace!("Board order is: {order:?}");
+    
+    log::trace!("Generating a board token...");
+    let mut rng = rand::rngs::OsRng::default();
+    let mut token: [u32; 16] = [0; 16];
+    rand::Fill::try_fill(&mut token, &mut rng)
+        .map_err(|_| (StatusCode::INTERNAL_SERVER_ERROR, outcome::req_error!("Failed to generate a secure board token.")))?;
+    // FIXME: only works on platforms where usize >= 32-bit?
+    let token: String = token.iter().map(|e| TOKEN_CHARS.get(*e as usize % 62).expect("randomly generated value to be a valid index"))
+        .collect::<String>();
+    log::trace!("Board token is: {token:?}");
 
-    log::trace!("Setting the board order...");
-    rconn.set(&order_key, match input.order {
-        Order::Ascending  => "LT",
-        Order::Descending => "GT",
-    }).await
-        .map_err(|_| RedisSetOrderError)?;
+    log::trace!("Starting Redis transaction...");
+    redis::cmd("MULTI").query_async(&mut rconn).await
+        .map_err(outcome::redis_cmd_failed)?;
 
-    Ok(Success)
+    log::trace!("Setting board order...");
+    rconn.set(&order_key, String::from(order)).await
+        .map_err(outcome::redis_cmd_failed)?;
+    
+    log::trace!("Setting board token...");
+    rconn.set(&token_key, &token).await
+        .map_err(outcome::redis_cmd_failed)?;
+    
+    log::trace!("Executing Redis transaction...");
+    redis::cmd("EXEC").query_async(&mut rconn).await
+        .map_err(outcome::redis_cmd_failed)?;
+
+    Ok((
+        StatusCode::OK,
+        Json(serde_json::to_value(RouteBoardPostOutput {name, order, token}).expect("to be able to serialize RouteBoardPostOutput"))
+    ))
 }

src/routes/home.rs

@@ -1,37 +1,7 @@
 //! Module defining routes for `/`.
 
-use axum::{Extension, Json};
-use axum::http::StatusCode;
-use axum::response::{IntoResponse, Response};
-use serde_json::json;
-
-
-/// Possible results for `GET /`.
-pub enum OutcomeHomeGet {
-    /// Could not connect to Redis.
-    RedisConnectionError,
-    /// Could not PING Redis.
-    RedisPingError,
-    /// Did not get a PONG back from Redis.
-    RedisPongError,
-    /// Ping successful.
-    Success,
-}
-
-use OutcomeHomeGet::*;
-
-impl IntoResponse for OutcomeHomeGet {
-    fn into_response(self) -> Response {
-        let (status, response) = match self {
-            RedisConnectionError => (StatusCode::GATEWAY_TIMEOUT, json!("Could not connect to Redis")),
-            RedisPingError => (StatusCode::BAD_GATEWAY, json!("Could not ping Redis")),
-            RedisPongError => (StatusCode::INTERNAL_SERVER_ERROR, json!("Redis did not pong back")),
-            Success => (StatusCode::OK, json!("Welcome to distributed_arcade! Redis seems to be working correctly."))
-        };
-
-        IntoResponse::into_response((status, Json(response)))
-    }
-}
+use axum::Extension;
+use crate::outcome;
 
 
 /// Handler for `GET /`.
@@ -39,17 +9,17 @@ impl IntoResponse for OutcomeHomeGet {
 /// Pings Redis to verify that everything is working correctly.
 pub async fn route_home_get(
     Extension(rclient): Extension<redis::Client>
-) -> Result<OutcomeHomeGet, OutcomeHomeGet> {
+) -> outcome::RequestResult {
 
     log::trace!("Connecting to Redis...");
     let mut rconn = rclient.get_async_connection().await
-        .map_err(|_| RedisConnectionError)?;
+        .map_err(outcome::redis_conn_failed)?;
 
-    log::trace!("Sending PING...");
-    let pong = redis::cmd("PING").query_async::<redis::aio::Connection, String>(&mut rconn).await
-        .map_err(|_| RedisPingError)?;
-
-    log::trace!("Expecting PONG: {pong:?}");
-    pong.eq("PONG")
-        .then_some(Success).ok_or(RedisPongError)
+    log::trace!("Sending PING and expecting PONG...");
+    redis::cmd("PING")
+        .query_async::<redis::aio::Connection, String>(&mut rconn).await
+        .map_err(outcome::redis_cmd_failed)?
+        .eq("PONG")
+        .then(outcome::success_null)
+        .ok_or_else(outcome::redis_unexpected_behaviour)
 }