1 files changed, 175 insertions, 0 deletions
diff --git a/src/expr/meta.rs b/src/expr/meta.rs
new file mode 100644
index 0000000..bf77774
--- /dev/null
+++ b/src/expr/meta.rs
@@ -0,0 +1,175 @@
+use super::{DeserializationError, Expression, Rule};
+use crate::sys::{self, libc};
+use std::os::raw::c_char;
+
+/// A meta expression refers to meta data associated with a packet.
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+#[non_exhaustive]
+pub enum Meta {
+    /// Packet ethertype protocol (skb->protocol), invalid in OUTPUT.
+    Protocol,
+    /// Packet mark.
+    Mark { set: bool },
+    /// Packet input interface index (dev->ifindex).
+    Iif,
+    /// Packet output interface index (dev->ifindex).
+    Oif,
+    /// Packet input interface name (dev->name)
+    IifName,
+    /// Packet output interface name (dev->name).
+    OifName,
+    /// Packet input interface type (dev->type).
+    IifType,
+    /// Packet output interface type (dev->type).
+    OifType,
+    /// Originating socket UID (fsuid).
+    SkUid,
+    /// Originating socket GID (fsgid).
+    SkGid,
+    /// Netfilter protocol (Transport layer protocol).
+    NfProto,
+    /// Layer 4 protocol number.
+    L4Proto,
+    /// Socket control group (skb->sk->sk_classid).
+    Cgroup,
+    /// A 32bit pseudo-random number
+    PRandom,
+}
+
+impl Meta {
+    /// Returns the corresponding `NFT_*` constant for this meta expression.
+    pub fn to_raw_key(&self) -> u32 {
+        use Meta::*;
+        match *self {
+            Protocol => libc::NFT_META_PROTOCOL as u32,
+            Mark { .. } => libc::NFT_META_MARK as u32,
+            Iif => libc::NFT_META_IIF as u32,
+            Oif => libc::NFT_META_OIF as u32,
+            IifName => libc::NFT_META_IIFNAME as u32,
+            OifName => libc::NFT_META_OIFNAME as u32,
+            IifType => libc::NFT_META_IIFTYPE as u32,
+            OifType => libc::NFT_META_OIFTYPE as u32,
+            SkUid => libc::NFT_META_SKUID as u32,
+            SkGid => libc::NFT_META_SKGID as u32,
+            NfProto => libc::NFT_META_NFPROTO as u32,
+            L4Proto => libc::NFT_META_L4PROTO as u32,
+            Cgroup => libc::NFT_META_CGROUP as u32,
+            PRandom => libc::NFT_META_PRANDOM as u32,
+        }
+    }
+
+    fn from_raw(val: u32) -> Result<Self, DeserializationError> {
+        match val as i32 {
+            libc::NFT_META_PROTOCOL => Ok(Self::Protocol),
+            libc::NFT_META_MARK => Ok(Self::Mark { set: false }),
+            libc::NFT_META_IIF => Ok(Self::Iif),
+            libc::NFT_META_OIF => Ok(Self::Oif),
+            libc::NFT_META_IIFNAME => Ok(Self::IifName),
+            libc::NFT_META_OIFNAME => Ok(Self::OifName),
+            libc::NFT_META_IIFTYPE => Ok(Self::IifType),
+            libc::NFT_META_OIFTYPE => Ok(Self::OifType),
+            libc::NFT_META_SKUID => Ok(Self::SkUid),
+            libc::NFT_META_SKGID => Ok(Self::SkGid),
+            libc::NFT_META_NFPROTO => Ok(Self::NfProto),
+            libc::NFT_META_L4PROTO => Ok(Self::L4Proto),
+            libc::NFT_META_CGROUP => Ok(Self::Cgroup),
+            libc::NFT_META_PRANDOM => Ok(Self::PRandom),
+            _ => Err(DeserializationError::InvalidValue),
+        }
+    }
+}
+
+impl Expression for Meta {
+    fn get_raw_name() -> *const libc::c_char {
+        b"meta\0" as *const _ as *const c_char
+    }
+
+    fn from_expr(expr: *const sys::nftnl_expr) -> Result<Self, DeserializationError>
+    where
+        Self: Sized,
+    {
+        unsafe {
+            let mut ret = Self::from_raw(sys::nftnl_expr_get_u32(
+                expr,
+                sys::NFTNL_EXPR_META_KEY as u16,
+            ))?;
+
+            if let Self::Mark { ref mut set } = ret {
+                *set = sys::nftnl_expr_is_set(expr, sys::NFTNL_EXPR_META_SREG as u16);
+            }
+
+            Ok(ret)
+        }
+    }
+
+    fn to_expr(&self, _rule: &Rule) -> *mut sys::nftnl_expr {
+        unsafe {
+            let expr = try_alloc!(sys::nftnl_expr_alloc(Self::get_raw_name()));
+
+            if let Meta::Mark { set: true } = self {
+                sys::nftnl_expr_set_u32(
+                    expr,
+                    sys::NFTNL_EXPR_META_SREG as u16,
+                    libc::NFT_REG_1 as u32,
+                );
+            } else {
+                sys::nftnl_expr_set_u32(
+                    expr,
+                    sys::NFTNL_EXPR_META_DREG as u16,
+                    libc::NFT_REG_1 as u32,
+                );
+            }
+            sys::nftnl_expr_set_u32(expr, sys::NFTNL_EXPR_META_KEY as u16, self.to_raw_key());
+            expr
+        }
+    }
+}
+
+#[macro_export]
+macro_rules! nft_expr_meta {
+    (proto) => {
+        $crate::expr::Meta::Protocol
+    };
+    (mark set) => {
+        $crate::expr::Meta::Mark { set: true }
+    };
+    (mark) => {
+        $crate::expr::Meta::Mark { set: false }
+    };
+    (iif) => {
+        $crate::expr::Meta::Iif
+    };
+    (oif) => {
+        $crate::expr::Meta::Oif
+    };
+    (iifname) => {
+        $crate::expr::Meta::IifName
+    };
+    (oifname) => {
+        $crate::expr::Meta::OifName
+    };
+    (iiftype) => {
+        $crate::expr::Meta::IifType
+    };
+    (oiftype) => {
+        $crate::expr::Meta::OifType
+    };
+    (skuid) => {
+        $crate::expr::Meta::SkUid
+    };
+    (skgid) => {
+        $crate::expr::Meta::SkGid
+    };
+    (nfproto) => {
+        $crate::expr::Meta::NfProto
+    };
+    (l4proto) => {
+        $crate::expr::Meta::L4Proto
+    };
+    (cgroup) => {
+        $crate::expr::Meta::Cgroup
+    };
+    (random) => {
+        $crate::expr::Meta::PRandom
+    };
+}