1 files changed, 112 insertions, 0 deletions
diff --git a/src/expr/log.rs b/src/expr/log.rs
new file mode 100644
index 0000000..5c06897
--- /dev/null
+++ b/src/expr/log.rs
@@ -0,0 +1,112 @@
+use super::{DeserializationError, Expression, Rule};
+use crate::sys;
+use std::ffi::{CStr, CString};
+use std::os::raw::c_char;
+use thiserror::Error;
+
+/// A Log expression will log all packets that match the rule.
+#[derive(Debug, PartialEq)]
+pub struct Log {
+    pub group: Option<LogGroup>,
+    pub prefix: Option<LogPrefix>,
+}
+
+impl Expression for Log {
+    fn get_raw_name() -> *const sys::libc::c_char {
+        b"log\0" as *const _ as *const c_char
+    }
+
+    fn from_expr(expr: *const sys::nftnl_expr) -> Result<Self, DeserializationError>
+    where
+        Self: Sized,
+    {
+        unsafe {
+            let mut group = None;
+            if sys::nftnl_expr_is_set(expr, sys::NFTNL_EXPR_LOG_GROUP as u16) {
+                group = Some(LogGroup(sys::nftnl_expr_get_u32(
+                    expr,
+                    sys::NFTNL_EXPR_LOG_GROUP as u16,
+                ) as u16));
+            }
+            let mut prefix = None;
+            if sys::nftnl_expr_is_set(expr, sys::NFTNL_EXPR_LOG_PREFIX as u16) {
+                let raw_prefix = sys::nftnl_expr_get_str(expr, sys::NFTNL_EXPR_LOG_PREFIX as u16);
+                if raw_prefix.is_null() {
+                    return Err(DeserializationError::NullPointer);
+                } else {
+                    prefix = Some(LogPrefix(CStr::from_ptr(raw_prefix).to_owned()));
+                }
+            }
+            Ok(Log { group, prefix })
+        }
+    }
+
+    fn to_expr(&self, _rule: &Rule) -> *mut sys::nftnl_expr {
+        unsafe {
+            let expr = try_alloc!(sys::nftnl_expr_alloc(b"log\0" as *const _ as *const c_char));
+            if let Some(log_group) = self.group {
+                sys::nftnl_expr_set_u32(expr, sys::NFTNL_EXPR_LOG_GROUP as u16, log_group.0 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
+        }
+    }
+}
+
+#[derive(Error, Debug)]
+pub enum LogPrefixError {
+    #[error("The log prefix string is more than 128 characters long")]
+    TooLongPrefix,
+    #[error("The log prefix string contains an invalid Nul character.")]
+    PrefixContainsANul(#[from] std::ffi::NulError),
+}
+
+/// The NFLOG group that will be assigned to each log line.
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
+pub struct LogGroup(pub u16);
+
+/// A prefix that will get prepended to each log line.
+#[derive(Debug, Clone, PartialEq)]
+pub struct LogPrefix(CString);
+
+impl LogPrefix {
+    /// Create a new LogPrefix from a String. Converts it to CString as needed by nftnl. Note
+    /// that LogPrefix should not be more than 127 characters long.
+    pub fn new(prefix: &str) -> Result<Self, LogPrefixError> {
+        if prefix.chars().count() > 127 {
+            return Err(LogPrefixError::TooLongPrefix);
+        }
+        Ok(LogPrefix(CString::new(prefix)?))
+    }
+}
+
+#[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,
+        }
+    };
+}