Adds an iterator over expressions to Rules

1 files changed, 45 insertions, 0 deletions

diff --git a/rustables/src/expr/mod.rs b/rustables/src/expr/mod.rs
index 99ea44b..a86b44d 100644
--- a/rustables/src/expr/mod.rs
+++ b/rustables/src/expr/mod.rs
@@ -3,9 +3,54 @@
 //!
 //! [`Rule`]: struct.Rule.html
 
+use std::ffi::CStr;
+use std::ffi::CString;
+use std::fmt::Debug;
+use std::rc::Rc;
+
 use super::rule::Rule;
 use rustables_sys::{self as sys, libc};
 
+pub struct ExpressionWrapper {
+    pub(crate) expr: *const sys::nftnl_expr,
+    // we also need the rule here to ensure that the rule lives as long as the `expr` pointer
+    #[allow(dead_code)]
+    pub(crate) rule: Rc<Rule>,
+}
+
+impl Debug for ExpressionWrapper {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{:?}", self.get_str())
+    }
+}
+
+impl ExpressionWrapper {
+    pub fn get_str(&self) -> CString {
+        let mut descr_buf = vec![0i8; 4096];
+        unsafe {
+            sys::nftnl_expr_snprintf(
+                descr_buf.as_mut_ptr(),
+                (descr_buf.len() - 1) as u64,
+                self.expr,
+                sys::NFTNL_OUTPUT_DEFAULT,
+                0,
+            );
+            CStr::from_ptr(descr_buf.as_ptr()).to_owned()
+        }
+    }
+
+    pub fn get_expr_kind(&self) -> Option<&CStr> {
+        unsafe {
+            let ptr = sys::nftnl_expr_get_str(self.expr, sys::NFTNL_EXPR_NAME as u16);
+            if !ptr.is_null() {
+                Some(CStr::from_ptr(ptr))
+            } else {
+                None
+            }
+        }
+    }
+}
+
 /// Trait for every safe wrapper of an nftables expression.
 pub trait Expression {
     /// Allocates and returns the low level `nftnl_expr` representation of this expression.