refactor: apply clippy let-chains and harden password validation

- Auto-fix 29 clippy warnings by converting nested if-lets to let-chains
- Harden password strength validator to reject restricted substrings
- Simplify rate_limiter state checks using is_none_or
- Improves idiomatic Rust style and overall security posture

Cargo.lock

@@ -1239,7 +1239,7 @@ dependencies = [
 
 [[package]]
 name = "nx9-auth"
-version = "0.3.0"
+version = "0.4.0"
 dependencies = [
  "anyhow",
  "argon2",

src/api/auth.rs

@@ -68,11 +68,10 @@ pub async fn login(
     }
 
     // Rate limit check (per IP)
-    if let Some(ip_str) = &ctx.ip_address {
-        if let Ok(ip_addr) = ip_str.parse::<std::net::IpAddr>() {
+    if let Some(ip_str) = &ctx.ip_address
+        && let Ok(ip_addr) = ip_str.parse::<std::net::IpAddr>() {
             state.rate_limiter.check(ip_addr)?;
         }
-    }
 
     // Look up user — always run comparable work on failure paths (timing).
     let user_opt = state
@@ -103,11 +102,10 @@ pub async fn login(
 
     if !is_authed {
         record_login_failure(&state, body.username.trim(), ip, ctx.user_agent.as_deref()).await;
-        if let Some(ip_str) = &ctx.ip_address {
-            if let Ok(ip_addr) = ip_str.parse::<std::net::IpAddr>() {
+        if let Some(ip_str) = &ctx.ip_address
+            && let Ok(ip_addr) = ip_str.parse::<std::net::IpAddr>() {
                 state.rate_limiter.record_failure(ip_addr);
             }
-        }
         // Non-enumerating error for both unknown user and bad password.
         return Err(AppError::InvalidCredentials);
     }
@@ -118,11 +116,10 @@ pub async fn login(
     };
 
     // Clear rate limit on success
-    if let Some(ip_str) = &ctx.ip_address {
-        if let Ok(ip_addr) = ip_str.parse::<std::net::IpAddr>() {
+    if let Some(ip_str) = &ctx.ip_address
+        && let Ok(ip_addr) = ip_str.parse::<std::net::IpAddr>() {
             state.rate_limiter.record_success(ip_addr);
         }
-    }
 
     // Session fixation mitigation: revoke prior sessions + refresh tokens.
     let _ = state

src/api/sessions.rs

@@ -103,13 +103,12 @@ pub async fn terminate_session(
     Path(id): Path<String>,
 ) -> Result<Json<Value>> {
     // If the user is trying to terminate the current session, disallow it
-    if let Some(current_id) = auth.session_id.as_deref() {
-        if id == current_id {
+    if let Some(current_id) = auth.session_id.as_deref()
+        && id == current_id {
             return Err(AppError::InvalidInput(
                 "Cannot terminate current session".into(),
             ));
         }
-    }
 
     // Admins can terminate any session, users can only terminate their own
     let is_admin = state

src/api/tenants.rs

@@ -53,11 +53,10 @@ pub async fn create_tenant(
 ) -> Result<Json<Value>> {
     require(&state.provider, &auth.user.id, "roles:manage").await?;
 
-    if let Some(ref s) = body.slug {
-        if !s.trim().is_empty() {
+    if let Some(ref s) = body.slug
+        && !s.trim().is_empty() {
             crate::identity::slug::validate_slug(s)?;
         }
-    }
 
     let id = uuid::Uuid::new_v4().to_string();
     let tenant = state
@@ -124,11 +123,10 @@ pub async fn update_tenant(
 ) -> Result<Json<Value>> {
     require(&state.provider, &auth.user.id, "roles:manage").await?;
 
-    if let Some(ref s) = body.slug {
-        if !s.trim().is_empty() {
+    if let Some(ref s) = body.slug
+        && !s.trim().is_empty() {
             crate::identity::slug::validate_slug(s)?;
         }
-    }
 
     state
         .provider

src/api/ui.rs

@@ -26,8 +26,8 @@ pub fn ui_dist_dir() -> PathBuf {
             return c.clone();
         }
     }
-    if let Ok(exe) = std::env::current_exe() {
-        if let Some(dir) = exe.parent() {
+    if let Ok(exe) = std::env::current_exe()
+        && let Some(dir) = exe.parent() {
             for rel in ["ui/dist", "../ui/dist", "../../ui/dist"] {
                 let candidate = dir.join(rel);
                 if candidate.exists() {
@@ -35,7 +35,6 @@ pub fn ui_dist_dir() -> PathBuf {
                 }
             }
         }
-    }
     PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("ui/dist")
 }
 

src/cli/mod.rs

@@ -566,11 +566,10 @@ async fn cmd_init(
     let sqlite_path = config.database.sqlite_path();
     let db_path = std::path::Path::new(&sqlite_path);
     println!("Creating database directory...");
-    if let Some(parent) = db_path.parent() {
-        if !parent.as_os_str().is_empty() {
+    if let Some(parent) = db_path.parent()
+        && !parent.as_os_str().is_empty() {
             std::fs::create_dir_all(parent)?;
         }
-    }
 
     // Create state directory
     if let Ok(home) = std::env::var("HOME") {
@@ -664,11 +663,10 @@ async fn run_init_validation(config: &Config, admin_skipped: bool) -> anyhow::Re
     let sqlite_path = config.database.sqlite_path();
     let db_path = std::path::Path::new(&sqlite_path);
     let mut dirs_ok = true;
-    if let Some(parent) = db_path.parent() {
-        if !parent.as_os_str().is_empty() && std::fs::create_dir_all(parent).is_err() {
+    if let Some(parent) = db_path.parent()
+        && !parent.as_os_str().is_empty() && std::fs::create_dir_all(parent).is_err() {
             dirs_ok = false;
         }
-    }
     if let Ok(home) = std::env::var("HOME") {
         let state_dir = std::path::Path::new(&home).join(".local/state/nx9-auth");
         if std::fs::create_dir_all(&state_dir).is_err() {
@@ -892,11 +890,10 @@ async fn cmd_backup(config: &Config, path: &std::path::Path) -> anyhow::Result<(
                 );
             }
 
-            if let Some(parent) = path.parent() {
-                if !parent.as_os_str().is_empty() {
+            if let Some(parent) = path.parent()
+                && !parent.as_os_str().is_empty() {
                     std::fs::create_dir_all(parent)?;
                 }
-            }
 
             if path.exists() {
                 std::fs::remove_file(path)?;
@@ -958,11 +955,10 @@ async fn cmd_restore(config: &Config, path: &std::path::Path) -> anyhow::Result<
         crate::config::DatabaseBackend::Sqlite => {
             let sqlite_path = config.database.sqlite_path();
             let target_path = std::path::Path::new(&sqlite_path);
-            if let Some(parent) = target_path.parent() {
-                if !parent.as_os_str().is_empty() {
+            if let Some(parent) = target_path.parent()
+                && !parent.as_os_str().is_empty() {
                     std::fs::create_dir_all(parent)?;
                 }
-            }
             std::fs::copy(path, target_path).with_context(|| {
                 format!("failed to restore backup to {}", target_path.display())
             })?;

src/config/mod.rs

@@ -293,14 +293,13 @@ impl Default for ShutdownConfig {
 // ── Helpers ──────────────────────────────────────────────────────────────────
 
 fn resolve_home_path(path: &str) -> String {
-    if let Some(stripped) = path.strip_prefix("~/") {
-        if let Ok(home) = std::env::var("HOME") {
+    if let Some(stripped) = path.strip_prefix("~/")
+        && let Ok(home) = std::env::var("HOME") {
             return Path::new(&home)
                 .join(stripped)
                 .to_string_lossy()
                 .into_owned();
         }
-    }
     path.to_string()
 }
 
@@ -312,12 +311,11 @@ impl Config {
         if let Some(ref mut path) = self.database.path {
             *path = resolve_home_path(path);
         }
-        if let Some(ref mut url) = self.database.url {
-            if let Some(stripped) = url.strip_prefix("sqlite://") {
+        if let Some(ref mut url) = self.database.url
+            && let Some(stripped) = url.strip_prefix("sqlite://") {
                 let clean = resolve_home_path(stripped);
                 *url = format!("sqlite://{clean}");
             }
-        }
     }
 
     /// Load and parse config from a TOML file.
@@ -372,11 +370,10 @@ impl Config {
 
     /// Default user configuration path (~/.config/nx9-auth/config.toml)
     pub fn default_user_config_path() -> Option<PathBuf> {
-        if let Ok(xdg) = std::env::var("XDG_CONFIG_HOME") {
-            if !xdg.is_empty() {
+        if let Ok(xdg) = std::env::var("XDG_CONFIG_HOME")
+            && !xdg.is_empty() {
                 return Some(PathBuf::from(xdg).join("nx9-auth/config.toml"));
             }
-        }
         if let Ok(home) = std::env::var("HOME") {
             return Some(PathBuf::from(home).join(".config/nx9-auth/config.toml"));
         }

src/db/mod.rs

@@ -57,13 +57,12 @@ pub async fn init_provider(
         #[cfg(feature = "sqlite")]
         DatabaseBackend::Sqlite => {
             let path = config.database.sqlite_path();
-            if let Some(parent) = std::path::Path::new(&path).parent() {
-                if !parent.as_os_str().is_empty() {
+            if let Some(parent) = std::path::Path::new(&path).parent()
+                && !parent.as_os_str().is_empty() {
                     std::fs::create_dir_all(parent).with_context(|| {
                         format!("failed to create database directory: {}", parent.display())
                     })?;
                 }
-            }
 
             let max_conn = config.database.max_connections.unwrap_or(16);
             let min_conn = config.database.min_connections.unwrap_or(1);
@@ -177,13 +176,12 @@ pub async fn init_provider(
 /// Helper function to create an SQLite pool for legacy CLI commands or tests.
 #[cfg(feature = "sqlite")]
 pub async fn create_pool(path: &str) -> Result<SqlitePool> {
-    if let Some(parent) = std::path::Path::new(path).parent() {
-        if !parent.as_os_str().is_empty() {
+    if let Some(parent) = std::path::Path::new(path).parent()
+        && !parent.as_os_str().is_empty() {
             std::fs::create_dir_all(parent).with_context(|| {
                 format!("failed to create database directory: {}", parent.display())
             })?;
         }
-    }
     let url = if path.starts_with("sqlite://") {
         path.to_string()
     } else {

src/identity/application_members.rs

@@ -221,8 +221,8 @@ pub async fn update(
         }
     }
 
-    if let Some(new_enabled) = enabled {
-        if new_enabled != existing.enabled {
+    if let Some(new_enabled) = enabled
+        && new_enabled != existing.enabled {
             let action = if new_enabled {
                 "application.member_enabled"
             } else {
@@ -255,7 +255,6 @@ pub async fn update(
                 .await
                 .map_err(AppError::Database)?;
         }
-    }
 
     provider
         .application_members()

src/identity/applications.rs

@@ -324,11 +324,9 @@ pub async fn update(
         .find_by_slug(slug)
         .await
         .map_err(AppError::Database)?
-    {
-        if other.entity_id != id || other.entity_type != "application" {
+        && (other.entity_id != id || other.entity_type != "application") {
             return Err(AppError::Conflict(format!("slug '{slug}' already exists")));
         }
-    }
 
     let redirect_json = redirect_uris.map(|v| serde_json::to_string(&v).unwrap_or_default());
     let scopes_json = scopes.map(|v| serde_json::to_string(&v).unwrap_or_default());

src/identity/roles.rs

@@ -191,11 +191,9 @@ pub async fn update_role(
         .find_by_name(name)
         .await
         .map_err(AppError::Database)?
-    {
-        if other.id != id {
+        && other.id != id {
             return Err(AppError::Conflict(format!("role '{name}' already exists")));
         }
-    }
 
     provider
         .roles()

src/middleware/auth.rs

@@ -72,9 +72,9 @@ where
         // 2. Try Authorization: Bearer — PAT first, then session token.
         //    Session tokens are returned from /auth/login for SPA clients that
         //    cannot rely solely on the HttpOnly cookie.
-        if let Some(auth_header) = parts.headers.get(axum::http::header::AUTHORIZATION) {
-            if let Ok(value) = auth_header.to_str() {
-                if let Some(raw) = value.strip_prefix("Bearer ") {
+        if let Some(auth_header) = parts.headers.get(axum::http::header::AUTHORIZATION)
+            && let Ok(value) = auth_header.to_str()
+                && let Some(raw) = value.strip_prefix("Bearer ") {
                     let raw = raw.trim();
 
                     // 2a. Personal access token
@@ -125,8 +125,6 @@ where
                         });
                     }
                 }
-            }
-        }
 
         Err(AppError::Unauthorized)
     }

src/runtime/application.rs

@@ -162,13 +162,12 @@ impl Lifecycle for Application {
             self.pool_handle = Some(pool_handle);
         }
 
-        if self.router.is_none() {
-            if let Some(provider) = &self.provider {
+        if self.router.is_none()
+            && let Some(provider) = &self.provider {
                 let app_state = crate::state::AppState::new(provider.clone(), config);
                 let router = crate::api::router::build(app_state);
                 self.router = Some(router);
             }
-        }
 
         Ok(())
     }

src/security/passwords.rs

@@ -17,10 +17,10 @@ pub fn hash_password(password: &str, cfg: &SecurityConfig) -> Result<String, App
             cfg.argon2_parallelism,
             None,
         )
-            .map_err(|e| {
-                tracing::error!(error = %e, "invalid argon2 params");
-                AppError::Internal
-            })?,
+        .map_err(|e| {
+            tracing::error!(error = %e, "invalid argon2 params");
+            AppError::Internal
+        })?,
     );
 
     let salt = SaltString::generate(&mut OsRng);
@@ -55,7 +55,10 @@ pub fn verify_password(password: &str, hash: &str) -> Result<bool, AppError> {
 pub fn verify_dummy(cfg: &SecurityConfig) -> Result<(), AppError> {
     // We hash a constant string to ensure the time taken is consistent
     // and aligns with the cost parameters defined in the config.
-    let _ = hash_password("dummy_password_for_timing_attacks_constant_time_alignment", cfg)?;
+    let _ = hash_password(
+        "dummy_password_for_timing_attacks_constant_time_alignment",
+        cfg,
+    )?;
     Ok(())
 }
 
@@ -70,32 +73,31 @@ pub fn validate_password_strength(password: &str, is_admin: bool) -> Result<(),
 
     let normalized = password.to_lowercase();
 
-    // Use a HashSet for O(1) exact matching against compromised/weak passwords
-    let weak_passwords: HashSet<&str> = [
-        "password",
-        "admin123",
-        "qwerty",
-        "12345678",
-        "123456789",
-        "administrator",
-        "nx9-auth",
-        "nx9auth",
-        "password123",
-        "admin",
-        "letmein",
-        "welcome",
-    ]
-        .iter()
-        .copied()
-        .collect();
+    // 1. Exact matches for highly common passwords
+    let exact_weak: HashSet<&str> = [
+        "password", "admin123", "qwerty", "12345678", "123456789",
+        "administrator", "nx9-auth", "nx9auth", "password123", "admin",
+        "letmein", "welcome", "password12345"
+    ].into_iter().collect();
 
-    if weak_passwords.contains(normalized.as_str()) {
+    if exact_weak.contains(normalized.as_str()) {
         return Err(AppError::InvalidInput(
             "password is too common or weak".to_string(),
         ));
     }
 
-    // Additional check: reject if it's a simple sequence or pattern
+    // 2. Substring matches for highly restricted roots
+    // We ban these substrings because "password12345" or "qwerty2024" are trivially guessable.
+    let banned_substrings = ["password", "qwerty", "123456"];
+    for banned in &banned_substrings {
+        if normalized.contains(banned) {
+            return Err(AppError::InvalidInput(
+                "password contains a restricted sequence".to_string(),
+            ));
+        }
+    }
+
+    // 3. Reject single repeated characters
     if password.chars().all(|c| c == password.chars().next().unwrap()) {
         return Err(AppError::InvalidInput(
             "password cannot be a single repeated character".to_string(),

src/security/rate_limit.rs

@@ -31,7 +31,7 @@ impl IpState {
 
     /// Returns true if this state is no longer active and can be removed.
     fn is_stale(&self, now: Instant) -> bool {
-        self.window.is_empty() && self.locked_until.map_or(true, |until| now >= until)
+        self.window.is_empty() && self.locked_until.is_none_or(|until| now >= until)
     }
 }
 
@@ -71,13 +71,11 @@ impl RateLimiter {
 
     /// Check if the given IP is currently allowed to attempt a login.
     pub fn check(&self, ip: IpAddr) -> Result<(), AppError> {
-        if let Some(s) = self.state.get(&ip) {
-            if let Some(until) = s.locked_until {
-                if Instant::now() < until {
+        if let Some(s) = self.state.get(&ip)
+            && let Some(until) = s.locked_until
+                && Instant::now() < until {
                     return Err(AppError::RateLimited);
                 }
-            }
-        }
         Ok(())
     }
 
@@ -87,11 +85,10 @@ impl RateLimiter {
         let now = Instant::now();
 
         // Clear the lockout if it has expired
-        if let Some(until) = s.locked_until {
-            if now >= until {
+        if let Some(until) = s.locked_until
+            && now >= until {
                 s.locked_until = None;
             }
-        }
 
         // Prune old failures outside the window
         let cutoff = now - self.window;

src/security/sessions.rs

@@ -77,8 +77,8 @@ pub async fn validate_session(
     let now = chrono::Utc::now();
 
     // Check absolute expiry
-    if let Ok(expires) = chrono::DateTime::parse_from_rfc3339(&session.expires_at) {
-        if now > expires {
+    if let Ok(expires) = chrono::DateTime::parse_from_rfc3339(&session.expires_at)
+        && now > expires {
             provider
                 .sessions()
                 .revoke(&session.id)
@@ -86,7 +86,6 @@ pub async fn validate_session(
                 .map_err(AppError::Database)?;
             return Ok(None);
         }
-    }
 
     // Check idle timeout
     if let Ok(last_seen) = chrono::DateTime::parse_from_rfc3339(&session.last_seen_at) {

src/security/tokens.rs

@@ -130,13 +130,11 @@ pub async fn validate_token(
     };
 
     // Check expiry if set
-    if let Some(ref exp) = token.expires_at {
-        if let Ok(expires) = chrono::DateTime::parse_from_rfc3339(exp) {
-            if chrono::Utc::now() > expires {
+    if let Some(ref exp) = token.expires_at
+        && let Ok(expires) = chrono::DateTime::parse_from_rfc3339(exp)
+            && chrono::Utc::now() > expires {
                 return Ok(None);
             }
-        }
-    }
 
     // Touch last_used_at (fire-and-forget)
     let _ = provider.tokens().update_last_used(&token.id).await;