feat: add sanitization check, refactor error returns

Cargo.lock

@@ -1049,6 +1049,7 @@ dependencies = [
  "serde-aux",
  "serde_json",
  "sqlx",
+ "strum_macros",
  "tokio",
  "tower",
  "tower-http",
@@ -1056,6 +1057,7 @@ dependencies = [
  "tracing-bunyan-formatter",
  "tracing-log 0.2.0",
  "tracing-subscriber",
+ "unicode-segmentation",
  "uuid",
 ]
 
@@ -2253,6 +2255,19 @@ dependencies = [
  "unicode-normalization",
 ]
 
+[[package]]
+name = "strum_macros"
+version = "0.26.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a3417fc93d76740d974a01654a09777cb500428cc874ca9f45edfe0c4d4cd18"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "rustversion",
+ "syn 2.0.32",
+]
+
 [[package]]
 name = "subtle"
 version = "2.5.0"

Cargo.toml

@@ -34,7 +34,8 @@ tracing-subscriber = { version = "0.3", features = ["registry", "env-filter"] }
 tracing-bunyan-formatter = "0.3"
 tracing-log = "0.2"
 secrecy = { version = "0.8", features = ["serde"] }
-# lazy-regex = "3"
+unicode-segmentation = "1"
+strum_macros = "0.26"
 # async-trait = "0.1"
 # strum_macros = "0.25"
 

src/error.rs

@@ -15,7 +15,11 @@ pub enum Error {
     AuthFailCtxNotInRequestExt,
 
     // -- Model errors.
+    // FIXME: Delete this:
     PropertyDeleteFailIdNotFound { id: u64 },
+
+    // -- Service errors.
+    SubscriptionFailInvalidName,
 }
 
 impl Error {
@@ -30,11 +34,18 @@ impl Error {
             | Self::AuthFailCtxNotInRequestExt => (StatusCode::FORBIDDEN, ClientError::NO_AUTH),
 
             // -- Model.
+            // FIXME: Delete this:
             Self::PropertyDeleteFailIdNotFound { .. } => {
                 (StatusCode::BAD_REQUEST, ClientError::INVALID_PARAMS)
             }
 
+            // -- Subscription.
+            Self::SubscriptionFailInvalidName => {
+                (StatusCode::BAD_REQUEST, ClientError::INVALID_PARAMS)
+            }
+
             // -- Fallback.
+            #[allow(unreachable_patterns)]
             _ => (
                 StatusCode::INTERNAL_SERVER_ERROR,
                 ClientError::SERVICE_ERROR,
@@ -45,7 +56,7 @@ impl Error {
 
 impl IntoResponse for Error {
     fn into_response(self) -> Response {
-        println!("->> {:<12} - {self:?}", "INTO_RESPONSE");
+        // TODO: trace something here maybe.
 
         // Create a placeholder Axum response.
         let mut response = StatusCode::INTERNAL_SERVER_ERROR.into_response();

src/lib.rs

@@ -2,7 +2,10 @@
 //!
 //! This is an example documentation string for the root of the crate.
 
+pub use self::error::{Error, Result};
+
 pub mod configuration;
+pub mod error;
 pub mod routes;
 pub mod startup;
 pub mod telemetry;

src/routes/subscriptions.rs

@@ -1,10 +1,16 @@
+use crate::Result;
 use axum::extract::State;
 use axum::routing::post;
 use axum::Form;
 use axum::Router;
+use axum::{
+    http::StatusCode,
+    response::{IntoResponse, Response},
+};
 use chrono::Utc;
 use serde::Deserialize;
 use sqlx::PgPool;
+use unicode_segmentation::UnicodeSegmentation;
 use uuid::Uuid;
 
 #[derive(Debug, Deserialize)]
@@ -13,6 +19,32 @@ struct FormData {
     name: String,
 }
 
+/// Returns `true` if the input satisfies all our validation constraints
+/// on subscriber names, `false` otherwise.
+pub fn is_valid_name(s: &str) -> bool {
+    // `.trim()` returns a view over the input `s` without trailing
+    // whitespace-like characters.
+    // `.is_empty` checks if the view contains any character.
+    let is_empty_or_whitespace = s.trim().is_empty();
+
+    // A grapheme is defined by the Unicode standard as a "user-perceived"
+    // character: `å` is a single grapheme, but it is composed of two characters
+    // (`a` and `̊`).
+    //
+    // `graphemes` returns an iterator over the graphemes in the input `s`.
+    // `true` specifies that we want to use the extended grapheme definition set,
+    // the recommended one.
+    let is_too_long = s.graphemes(true).count() > 256;
+
+    // Iterate over all characters in the input `s` to check if any of them matches
+    // one of the characters in the forbidden array.
+    let forbidden_characters = ['/', '(', ')', '"', '<', '>', '\\', '{', '}'];
+    let contains_forbidden_characters = s.chars().any(|g| forbidden_characters.contains(&g));
+
+    // Return `false` if any of our conditions have been violated
+    !(is_empty_or_whitespace || is_too_long || contains_forbidden_characters)
+}
+
 #[tracing::instrument(
     name = "Adding a new subscriber",
     skip(form, pool),
@@ -22,13 +54,19 @@ struct FormData {
         subscriber_name = %form.name
     )
 )]
-pub async fn subscribe(State(pool): State<PgPool>, Form(form): Form<FormData>) {
+pub async fn subscribe(State(pool): State<PgPool>, Form(form): Form<FormData>) -> Response {
+    if !is_valid_name(&form.name) {
+        tracing::error!("Failed to add subscriber to the database");
+        return (StatusCode::BAD_REQUEST, "Invalid name").into_response();
+    }
     match insert_subscriber(&pool, &form).await {
         Ok(_) => {
             tracing::info!("Subscriber added to the database");
+            return (StatusCode::OK,).into_response();
         }
         Err(_) => {
             tracing::error!("Failed to add subscriber to the database");
+            return (StatusCode::INTERNAL_SERVER_ERROR, "Something went wrong").into_response();
         }
     }
 }
@@ -37,8 +75,8 @@ pub async fn subscribe(State(pool): State<PgPool>, Form(form): Form<FormData>) {
     name = "Saving new subscriber details in the database",
     skip(form, pool)
 )]
-pub async fn insert_subscriber(pool: &PgPool, form: &FormData) -> Result<(), sqlx::Error> {
-    sqlx::query!(
+pub async fn insert_subscriber(pool: &PgPool, form: &FormData) -> Result<()> {
+    let _ = sqlx::query!(
         r#"
             INSERT INTO subscriptions (id, email, name, subscribed_at)
             VALUES ($1, $2, $3, $4)
@@ -55,7 +93,7 @@ pub async fn insert_subscriber(pool: &PgPool, form: &FormData) -> Result<(), sql
     .map_err(|e| {
         tracing::error!("Failed to execute query: {:?}", e);
         e
-    })?;
+    });
     Ok(())
 }
 

tests/health_check.rs

@@ -70,7 +70,7 @@ async fn subscribe_returns_a_422_when_data_is_missing() {
         assert_eq!(
             422,
             response.status().as_u16(),
-            "The API did not fail with 400 Bad Request when the payload was {}.",
+            "The API did not fail with 422 when the payload was {}.",
             error_message
         );
     }
@@ -104,6 +104,37 @@ async fn subscribe_returns_a_200_for_valid_form_data() {
     assert_eq!(saved.name, "le guin");
 }
 
+#[tokio::test]
+async fn subscribe_returns_a_200_when_fields_are_present_but_empty() {
+    // Arrange
+    let app = spawn_app().await;
+    let client = reqwest::Client::new();
+    let test_cases = vec![
+        ("name=&email=ursula_le_guin%40gmail.com", "empty name"),
+        ("name=Ursula&email=", "empty email"),
+        ("name=Ursula&email=definitely-not-an-email", "invalid email"),
+    ];
+
+    for (body, description) in test_cases {
+        // Act
+        let response = client
+            .post(&format!("{}/subscriptions", &app.address))
+            .header("Content-Type", "application/x-www-form-urlencoded")
+            .body(body)
+            .send()
+            .await
+            .expect("Failed to execute request.");
+
+        // Assert
+        assert_eq!(
+            200,
+            response.status().as_u16(),
+            "The API did not return a 200 OK when the payload was {}.",
+            description
+        );
+    }
+}
+
 async fn spawn_app() -> TestApp {
     // The first time `initialize` is invoked the code in `TRACING` is executed.
     // All other invocations will instead skip execution.