'sculpting' as an opt-in feature

Packet 'sculpting' is an experimental feature and WIP, it needs more
work before it can be made a default feature.  Making sculpting as an
opt-in feature so that it does not affect the existing users as the
feature is being developed.

Signed-off-by: Abhijit Gadgil <[email protected]>

Cargo.toml

@@ -74,5 +74,6 @@ walkdir = "2"
 [features]
 python-bindings = ['pyo3']
 logging = ["log"]
+sculpting = []
 
 wasm = ['wasm-bindgen']

examples/packet_sculpting.rs

@@ -1,7 +1,9 @@
+#![allow(unused)]
 use std::error::Error;
 
 use scalpel::{layers, ENCAP_TYPE_ETH};
 
+#[cfg(feature = "sculpting")]
 fn main() -> Result<(), Box<dyn Error>> {
     let _ = scalpel::register_defaults()?;
 
@@ -18,16 +20,19 @@ fn main() -> Result<(), Box<dyn Error>> {
 
     let res_string = result[0]
         .iter()
-        .fold(String::new(), |acc, num| {
-            acc + "0x" + &num.to_string() + " "
-        })
+        .fold(String::new(), |acc, num| format!("{}{:02x}", acc, num))
         .trim_end()
         .to_string();
 
-    println!("res: {:#?}", res_string);
+    println!("Packet Data: {:#?}", res_string);
 
     let p = scalpel::Packet::from_bytes(&result[0], ENCAP_TYPE_ETH);
     println!("{}", serde_json::to_string_pretty(&p.unwrap()).unwrap());
 
     Ok(())
 }
+
+#[cfg(not(feature = "sculpting"))]
+fn main() {
+    eprintln!("Feature 'sculpting' is required for this example!.");
+}

src/builder.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "sculpting")]
+
 use crate::{errors::Error, Layer, Packet};
 
 #[derive(Debug, Default)]

src/layer.rs

@@ -30,6 +30,7 @@ pub trait Layer: Send + Debug + erased_serde::Serialize {
         bytes: &[u8],
     ) -> Result<(Option<Box<dyn Layer + Send>>, usize), Error>;
 
+    #[cfg(feature = "sculpting")]
     /// Main 'encoder' function.
     ///
     /// The return value is a `Vec<u8>` on success. This indicates the encoded packet of the

src/layers/ethernet/mod.rs

@@ -4,7 +4,7 @@ use core::convert::TryInto;
 
 // FIXME: Should work with no_std
 use std::collections::HashMap;
-use std::sync::{RwLock,OnceLock};
+use std::sync::{OnceLock, RwLock};
 
 use serde::Serialize;
 
@@ -19,7 +19,8 @@ pub fn get_ethertypes_map() -> &'static RwLock<HashMap<EtherType, LayerCreatorFn
     ///
     /// The creator function simply creates a `default` L3 struct that implements the dissector
     /// for the Layer.
-    pub(crate) static ETHERTYPES_MAP: OnceLock<RwLock<HashMap<EtherType, LayerCreatorFn>>> = OnceLock::new();
+    pub(crate) static ETHERTYPES_MAP: OnceLock<RwLock<HashMap<EtherType, LayerCreatorFn>>> =
+        OnceLock::new();
     ETHERTYPES_MAP.get_or_init(|| RwLock::new(HashMap::new()))
 }
 
@@ -91,6 +92,7 @@ impl Layer for Ethernet {
         }
     }
 
+    #[cfg(feature = "sculpting")]
     fn stack_and_encode(
         &mut self,
         next_layer: Option<&[u8]>,

src/layers/ipv4.rs

@@ -255,6 +255,7 @@ impl IPv4 {
         Ok(((len as u8, data), i))
     }
 
+    #[cfg(feature = "sculpting")]
     fn calculate_checksum(_bytes: &[u8]) -> u16 {
         0
     }
@@ -322,6 +323,7 @@ impl Layer for IPv4 {
         "ip"
     }
 
+    #[cfg(feature = "sculpting")]
     fn stack_and_encode(
         &mut self,
         next_layer: Option<&[u8]>,