Rework Scheme serialization

This change is a necessary rework of scheme serialization to allow
for additional field properties that will be introduced in a future
commit.

Before this change, a serialized scheme was a map of field name to field type.
After this change, a serialized scheme is a map of field name to
field definition object, which only contain its type for now but can
be extended with additional properties.

Author: marmeladema

engine/src/scheme.rs

@@ -9,6 +9,7 @@ use crate::{
     types::{GetType, RhsValue, Type},
 };
 use fnv::FnvBuildHasher;
+use serde::de::Visitor;
 use serde::ser::SerializeMap;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 use std::collections::hash_map::Entry;
@@ -139,7 +140,7 @@ impl<'s> FieldRef<'s> {
     /// Returns the field's name as recorded in the [`Scheme`](struct@Scheme).
     #[inline]
     pub fn name(&self) -> &'s str {
-        &self.scheme.inner.fields[self.index].0
+        &self.scheme.inner.fields[self.index].name
     }
 
     /// Get the field's index in the [`Scheme`](struct@Scheme) identifier's list.
@@ -183,7 +184,7 @@ impl<'s> FieldRef<'s> {
 impl GetType for FieldRef<'_> {
     #[inline]
     fn get_type(&self) -> Type {
-        self.scheme.inner.fields[self.index].1
+        self.scheme.inner.fields[self.index].ty
     }
 }
 
@@ -217,7 +218,7 @@ impl Field {
     /// Returns the field's name as recorded in the [`Scheme`](struct@Scheme).
     #[inline]
     pub fn name(&self) -> &str {
-        &self.scheme.inner.fields[self.index].0
+        &self.scheme.inner.fields[self.index].name
     }
 
     /// Get the field's index in the [`Scheme`](struct@Scheme) identifier's list.
@@ -245,7 +246,7 @@ impl Field {
 impl GetType for Field {
     #[inline]
     fn get_type(&self) -> Type {
-        self.scheme.inner.fields[self.index].1
+        self.scheme.inner.fields[self.index].ty
     }
 }
 
@@ -609,10 +610,16 @@ pub struct ListRedefinitionError(Type);
 
 type IdentifierName = Arc<str>;
 
+#[derive(Debug, PartialEq)]
+struct FieldDefinition {
+    name: IdentifierName,
+    ty: Type,
+}
+
 /// A builder for a [`Scheme`].
 #[derive(Default, Debug)]
 pub struct SchemeBuilder {
-    fields: Vec<(IdentifierName, Type)>,
+    fields: Vec<FieldDefinition>,
     functions: Vec<(IdentifierName, Box<dyn FunctionDefinition>)>,
     items: HashMap<IdentifierName, SchemeItem, FnvBuildHasher>,
 
@@ -643,7 +650,10 @@ impl SchemeBuilder {
             },
             Entry::Vacant(entry) => {
                 let index = self.fields.len();
-                self.fields.push((entry.key().clone(), ty));
+                self.fields.push(FieldDefinition {
+                    name: entry.key().clone(),
+                    ty,
+                });
                 entry.insert(SchemeItem::Field(index));
                 Ok(())
             }
@@ -737,14 +747,21 @@ impl Hash for Scheme {
     }
 }
 
+#[derive(Deserialize, Serialize)]
+struct SerdeField {
+    #[serde(rename = "type")]
+    ty: Type,
+}
+
 impl Serialize for Scheme {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: Serializer,
     {
-        let mut map = serializer.serialize_map(Some(self.field_count()))?;
-        for f in self.fields() {
-            map.serialize_entry(f.name(), &f.get_type())?;
+        let fields = self.fields();
+        let mut map = serializer.serialize_map(Some(fields.len()))?;
+        for f in fields {
+            map.serialize_entry(f.name(), &SerdeField { ty: f.get_type() })?;
         }
         map.end()
     }
@@ -757,12 +774,31 @@ impl<'de> Deserialize<'de> for Scheme {
     {
         use serde::de::Error;
 
-        let mut builder = SchemeBuilder::new();
-        let map: HashMap<String, Type> = HashMap::<String, Type>::deserialize(deserializer)?;
-        for (name, ty) in map {
-            builder.add_field(&name, ty).map_err(D::Error::custom)?;
+        struct FieldMapVisitor;
+
+        impl<'de> Visitor<'de> for FieldMapVisitor {
+            type Value = SchemeBuilder;
+
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                formatter.write_str("a wirefilter scheme")
+            }
+
+            fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
+            where
+                A: serde::de::MapAccess<'de>,
+            {
+                let mut builder = SchemeBuilder::new();
+                while let Some((name, SerdeField { ty })) = map.next_entry::<&str, SerdeField>()? {
+                    builder.add_field(name, ty).map_err(A::Error::custom)?;
+                }
+
+                Ok(builder)
+            }
         }
-        Ok(builder.build())
+
+        deserializer
+            .deserialize_map(FieldMapVisitor)
+            .map(|builder| builder.build())
     }
 }
 
@@ -1743,3 +1779,24 @@ fn test_scheme_iter_fields() {
         ]
     );
 }
+
+#[test]
+fn test_scheme_json_serialization() {
+    let scheme = Scheme! {
+        bytes: Bytes,
+        int: Int,
+        bool: Bool,
+        ip: Ip,
+        map_of_bytes: Map(Bytes),
+        map_of_array_of_bytes: Map(Array(Bytes)),
+        array_of_bytes: Array(Bytes),
+        array_of_map_of_bytes: Array(Map(Bytes)),
+    }
+    .build();
+
+    let json = serde_json::to_string(&scheme).unwrap();
+
+    let new_scheme = serde_json::from_str::<Scheme>(&json).unwrap();
+
+    assert_eq!(scheme.inner.fields, new_scheme.inner.fields);
+}

ffi/tests/ctests/src/tests.c

@@ -305,7 +305,7 @@ void wirefilter_ffi_ctest_scheme_serialize() {
     rust_assert(json.ptr != NULL && json.len > 0, "could not serialize scheme to JSON");
 
     rust_assert(
-        strncmp(json.ptr, "{\"http.host\":\"Bytes\",\"ip.src\":\"Ip\",\"ip.dst\":\"Ip\",\"ssl\":\"Bool\",\"tcp.port\":\"Int\",\"http.headers\":{\"Map\":\"Bytes\"},\"http.cookies\":{\"Array\":\"Bytes\"}}", json.len) == 0,
+        strncmp(json.ptr, "{\"http.host\":{\"type\":\"Bytes\"},\"ip.src\":{\"type\":\"Ip\"},\"ip.dst\":{\"type\":\"Ip\"},\"ssl\":{\"type\":\"Bool\"},\"tcp.port\":{\"type\":\"Int\"},\"http.headers\":{\"type\":{\"Map\":\"Bytes\"}},\"http.cookies\":{\"type\":{\"Array\":\"Bytes\"}}}", json.len) == 0,
         "invalid JSON serialization"
     );