1 files changed, 72 insertions, 2 deletions
diff --git a/rustables/src/expr/log.rs b/rustables/src/expr/log.rs
index d6e0089..4345f41 100644
--- a/rustables/src/expr/log.rs
+++ b/rustables/src/expr/log.rs
@@ -1,12 +1,82 @@
 use super::{Expression, Rule};
 use rustables_sys as sys;
 use std::os::raw::c_char;
+use std::ffi::CString;
 
 /// A Log expression will log all packets that match the rule.
-pub struct Log;
+pub struct Log {
+    pub group: Option<LogGroup>,
+    pub prefix: Option<LogPrefix>
+}
 
 impl Expression for Log {
     fn to_expr(&self, _rule: &Rule) -> *mut sys::nftnl_expr {
-        try_alloc!(unsafe { sys::nftnl_expr_alloc(b"log\0" as *const _ as *const c_char) })
+        unsafe {
+            let expr = try_alloc!(sys::nftnl_expr_alloc(
+                b"log\0" as *const _ as *const c_char
+            ));
+            if let Some(group) = self.group {
+                sys::nftnl_expr_set_u32(
+                    expr,
+                    sys::NFTNL_EXPR_LOG_GROUP as u16,
+                    group as u32,
+                );
+            };
+            if let Some(LogPrefix(prefix)) = &self.prefix {
+                sys::nftnl_expr_set_str(
+                    expr,
+                    sys::NFTNL_EXPR_LOG_PREFIX as u16,
+                    prefix.as_ptr()
+                );
+            };
+
+            expr
+        }
+    }
+}
+
+
+/// Enumeration of possible NFLOG groups.
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
+pub enum LogGroup {
+    LogGroupZero,
+    LogGroupOne,
+    LogGroupTwo,
+    LogGroupThree,
+    LogGroupFour,
+    LogGroupFive,
+    LogGroupSix,
+    LogGroupSeven,
+}
+
+/// A prefix that will get prepended to each log line.
+#[derive(Clone)]
+pub struct LogPrefix(pub CString);
+
+impl LogPrefix {
+    /// Create a new LogPrefix from a String. Converts it to CString as needed by nftables.
+    pub fn new(prefix: &str) -> Result<Self, std::ffi::NulError> {
+        // TODO check for prefix size constraints.
+        match CString::new(prefix) {
+            Ok(string) => Ok(LogPrefix(string)),
+            Err(error)=> Err(error)
+        }
     }
 }
+
+
+#[macro_export]
+macro_rules! nft_expr_log {
+    (group $group:ident prefix $prefix:expr) => {
+        $crate::expr::Log { group: $group, prefix: $prefix }
+    };
+    (prefix $prefix:expr) => {
+        $crate::expr::Log { group: None, prefix: $prefix }
+    };
+    (group $group:ident) => {
+        $crate::expr::Log { group: $group, prefix: None }
+    };
+    () => {
+        $crate::expr::Log { group: None, prefix: None }
+    };
+}