detect/ftp: Add parser for ftp.mode keyword

Issue: 7505

Add a parser for the ftp.mode command that returns the state struct. Add
a function to free the object it allocates.

rust/src/ftp/ftp.rs

@@ -16,7 +16,8 @@
  */
 
 use std;
-use std::ffi::CString;
+use std::ptr;
+use std::ffi::{CStr, CString};
 use std::os::raw::{c_char, c_int, c_void};
 
 use crate::conf::{conf_get, get_memval};
@@ -24,6 +25,11 @@ use crate::core::*;
 use crate::ftp::constant::*;
 use lazy_static::lazy_static;
 
+#[repr(C)]
+pub struct DetectFtpModeData {
+    pub active: bool,
+}
+
 /// cbindgen:ignore
 #[repr(C)]
 pub struct FtpCommand {
@@ -218,6 +224,36 @@ pub unsafe extern "C" fn SCFTPGetConfigValues(
     }
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn SCFTPParseMode(c_str: *const c_char) -> *mut DetectFtpModeData {
+    if c_str.is_null() {
+        return ptr::null_mut();
+    }
+
+    // Convert C string to Rust string slice
+    let Ok(input_str) = CStr::from_ptr(c_str).to_str() else {
+        return ptr::null_mut();
+    };
+
+    // Check for case-insensitive match
+    let is_active = match input_str.trim().to_ascii_lowercase().as_str() {
+        "active" => true,
+        "passive" => false,
+        _ => return ptr::null_mut(), // invalid input
+    };
+
+    // Return a pointer to a heap-allocated struct
+    let boxed = Box::new(DetectFtpModeData { active: is_active });
+    Box::into_raw(boxed)
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn SCFTPFreeModeData(ptr: *mut DetectFtpModeData) {
+    if !ptr.is_null() {
+        drop(Box::from_raw(ptr));
+    }
+}
+
 /// Returns *mut FtpTransferCmd
 #[no_mangle]
 pub unsafe extern "C" fn SCFTPTransferCmdNew() -> *mut FtpTransferCmd {