Add http_port range validation (0 or 1-65535)

Change http_port type from u16 to u32 to allow out-of-range values to be
caught by validation. Add HttpPortInvalid error variant and validation check
for http_port > 65535. Add test for http_port=65536 producing HttpPortInvalid.
http_port=0 (disabled) remains valid per existing test.

src/config/static_config.rs

@@ -33,7 +33,7 @@ pub fn default_shutdown_timeout_secs() -> u64 {
 pub struct ListenerConfig {
     pub bind_addr: String,
     #[serde(default = "default_http_port")]
-    pub http_port: u16,
+    pub http_port: u32,
     #[serde(default = "default_https_port")]
     pub https_port: u16,
     pub tls: TlsConfig,
@@ -42,7 +42,7 @@ pub struct ListenerConfig {
 }
 
 #[allow(dead_code)]
-fn default_http_port() -> u16 {
+fn default_http_port() -> u32 {
     80
 }
 

src/config/validation.rs

@@ -41,19 +41,19 @@ pub enum ValidationError {
     #[error("body.limit_bytes must be > 0, got {value}")]
     BodyLimitBytesZero { value: u64 },
     #[error("duplicate bind_addr:http_port combination: {bind_addr}:{http_port}")]
-    DuplicateHttpBind { bind_addr: String, http_port: u16 },
+    DuplicateHttpBind { bind_addr: String, http_port: u32 },
     #[error(
         "listener {bind_addr}: http_port ({http_port}) and https_port ({https_port}) must differ"
     )]
     HttpsAndHttpPortSame {
         bind_addr: String,
-        http_port: u16,
+        http_port: u32,
         https_port: u16,
     },
     #[error("listener {bind_addr}: https_port must be 1-65535, got {https_port}")]
     HttpsPortInvalid { bind_addr: String, https_port: u16 },
     #[error("listener {bind_addr}: http_port must be 0 (disabled) or 1-65535, got {http_port}")]
-    HttpPortInvalid { bind_addr: String, http_port: u16 },
+    HttpPortInvalid { bind_addr: String, http_port: u32 },
     #[error("health_check_port {health_check_port} conflicts with listener {bind_addr}:{port}")]
     HealthCheckPortConflict {
         health_check_port: u16,
@@ -120,7 +120,14 @@ pub fn validate(
             });
         }
 
-        if listener.http_port > 0 && listener.http_port == listener.https_port {
+        if listener.http_port > 65535 {
+            errors.push(ValidationError::HttpPortInvalid {
+                bind_addr: listener.bind_addr.clone(),
+                http_port: listener.http_port,
+            });
+        }
+
+        if listener.http_port > 0 && listener.http_port == listener.https_port as u32 {
             errors.push(ValidationError::HttpsAndHttpPortSame {
                 bind_addr: listener.bind_addr.clone(),
                 http_port: listener.http_port,
@@ -175,11 +182,14 @@ pub fn validate(
                     port: listener.https_port,
                 });
             }
-            if listener.http_port > 0 && static_config.health_check_port == listener.http_port {
+            if listener.http_port > 0
+                && listener.http_port <= 65535
+                && static_config.health_check_port as u32 == listener.http_port
+            {
                 errors.push(ValidationError::HealthCheckPortConflict {
                     health_check_port: static_config.health_check_port,
                     bind_addr: listener.bind_addr.clone(),
-                    port: listener.http_port,
+                    port: listener.http_port as u16,
                 });
             }
         }
@@ -710,6 +720,20 @@ mod tests {
             .any(|e| matches!(e, ValidationError::HttpsPortInvalid { .. })));
     }
 
+    #[test]
+    fn rule13_http_port_invalid() {
+        let mut config = valid_static_config();
+        config.listeners[0].http_port = 65536;
+        config.listeners[0].tls = make_acme_tls();
+        let dynamic = valid_dynamic_config();
+        let result = validate(&config, &dynamic, false);
+        assert!(result.is_err());
+        let errors = result.unwrap_err();
+        assert!(errors
+            .iter()
+            .any(|e| matches!(e, ValidationError::HttpPortInvalid { .. })));
+    }
+
     #[test]
     fn rule13_http_port_disabled_valid() {
         let mut config = valid_static_config();

tests/integration_test.rs

@@ -259,7 +259,7 @@ async fn test_rate_limit_eviction_task() {
 
 fn make_redirect_listener_config(
     bind_addr: &str,
-    http_port: u16,
+    http_port: u32,
     https_port: u16,
 ) -> reverse_proxy::config::static_config::ListenerConfig {
     reverse_proxy::config::static_config::ListenerConfig {