rust: derive macro for app-layer frame type

rust/derive/src/applayerframetype.rs

@@ -0,0 +1,105 @@
+/* Copyright (C) 2021 Open Information Security Foundation
+ *
+ * You can copy, redistribute or modify this Program under the terms of
+ * the GNU General Public License version 2 as published by the Free
+ * Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{self, parse_macro_input, DeriveInput};
+
+pub fn derive_app_layer_frame_type(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+    let name = input.ident;
+
+    let mut fields = Vec::new();
+    let mut vals = Vec::new();
+    let mut cstrings = Vec::new();
+    let mut names = Vec::new();
+
+    match input.data {
+        syn::Data::Enum(ref data) => {
+            for (i, v) in (&data.variants).into_iter().enumerate() {
+                fields.push(v.ident.clone());
+                let name = transform_name(&v.ident.to_string());
+                let cname = format!("{}\0", name);
+                names.push(name);
+                cstrings.push(cname);
+                vals.push(i as u8);
+            }
+        }
+        _ => panic!("AppLayerFrameType can only be derived for enums"),
+    }
+
+    let expanded = quote! {
+        impl crate::applayer::AppLayerFrameType for #name {
+            fn from_u8(val: u8) -> Option<Self> {
+                match val {
+                    #( #vals => Some(#name::#fields) ,)*
+                    _ => None,
+                }
+            }
+
+            fn as_u8(&self) -> u8 {
+                match *self {
+                    #( #name::#fields => #vals ,)*
+                }
+            }
+
+            fn to_cstring(&self) -> *const std::os::raw::c_char {
+                let s = match *self {
+                    #( #name::#fields => #cstrings ,)*
+                };
+                s.as_ptr() as *const std::os::raw::c_char
+            }
+
+            fn from_str(s: &str) -> Option<#name> {
+                match s {
+                    #( #names => Some(#name::#fields) ,)*
+                    _ => None
+                }
+            }
+        }
+    };
+
+    proc_macro::TokenStream::from(expanded)
+}
+
+fn transform_name(name: &str) -> String {
+    let mut xname = String::new();
+    let chars: Vec<char> = name.chars().collect();
+    for i in 0..chars.len() {
+        if i > 0 && i < chars.len() - 1 && chars[i].is_uppercase() && chars[i + 1].is_lowercase() {
+            xname.push('.');
+        }
+        xname.push_str(&chars[i].to_lowercase().to_string());
+    }
+    xname
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_transform_name() {
+        assert_eq!(transform_name("One"), "one");
+        assert_eq!(transform_name("OneTwo"), "one.two");
+        assert_eq!(transform_name("OneTwoThree"), "one.two.three");
+        assert_eq!(transform_name("NBSS"), "nbss");
+        assert_eq!(transform_name("NBSSHdr"), "nbss.hdr");
+        assert_eq!(transform_name("SMB3Data"), "smb3.data");
+    }
+}

rust/derive/src/lib.rs

@@ -20,6 +20,7 @@ extern crate proc_macro;
 use proc_macro::TokenStream;
 
 mod applayerevent;
+mod applayerframetype;
 
 /// The `AppLayerEvent` derive macro generates a `AppLayerEvent` trait
 /// implementation for enums that define AppLayerEvents.
@@ -40,3 +41,8 @@ mod applayerevent;
 pub fn derive_app_layer_event(input: TokenStream) -> TokenStream {
     applayerevent::derive_app_layer_event(input)
 }
+
+#[proc_macro_derive(AppLayerFrameType)]
+pub fn derive_app_layer_frame_type(input: TokenStream) -> TokenStream {
+    applayerframetype::derive_app_layer_frame_type(input)
+}