fix(sol-types): check signature in SolEvent if non-anonymous (#741)

* fix(sol-types): check signature in SolEvent if non-anonymous

* chore: clippy

crates/sol-macro-expander/src/expand/event.rs

@@ -98,6 +98,18 @@ pub(super) fn expand(cx: &ExpCtxt<'_>, event: &ItemEvent) -> Result<TokenStream>
         .enumerate()
         .map(|(i, p)| expand_event_topic_field(i, p, p.name.as_ref(), cx));
 
+    let check_signature = (!anonymous).then(|| {
+        quote! {
+            #[inline]
+            fn check_signature(topics: &<Self::TopicList as alloy_sol_types::SolType>::RustType) -> alloy_sol_types::Result<()> {
+                if topics.0 != Self::SIGNATURE_HASH {
+                    return Err(alloy_sol_types::Error::invalid_event_signature_hash(Self::SIGNATURE, topics.0, Self::SIGNATURE_HASH));
+                }
+                Ok(())
+            }
+        }
+    });
+
     let tokenize_body_impl = expand_event_tokenize(&event.parameters, cx);
 
     let encode_topics_impl = encode_first_topic
@@ -173,6 +185,8 @@ pub(super) fn expand(cx: &ExpCtxt<'_>, event: &ItemEvent) -> Result<TokenStream>
                     }
                 }
 
+                #check_signature
+
                 #[inline]
                 fn tokenize_body(&self) -> Self::DataToken<'_> {
                     #tokenize_body_impl

crates/sol-types/src/errors.rs

@@ -9,7 +9,7 @@
 
 use crate::abi;
 use alloc::{borrow::Cow, boxed::Box, collections::TryReserveError, string::String};
-use alloy_primitives::LogData;
+use alloy_primitives::{LogData, B256};
 use core::fmt;
 
 /// ABI result type.
@@ -147,6 +147,14 @@ impl Error {
     pub fn unknown_selector(name: &'static str, selector: [u8; 4]) -> Self {
         Self::UnknownSelector { name, selector: selector.into() }
     }
+
+    #[doc(hidden)] // Not public API.
+    #[cold]
+    pub fn invalid_event_signature_hash(name: &'static str, got: B256, expected: B256) -> Self {
+        Self::custom(format!(
+            "invalid signature hash for event {name:?}: got {got}, expected {expected}"
+        ))
+    }
 }
 
 impl From<hex::FromHexError> for Error {

crates/sol-types/src/types/event/mod.rs

@@ -54,11 +54,33 @@ pub trait SolEvent: Sized {
     const ANONYMOUS: bool;
 
     /// Convert decoded rust data to the event type.
+    ///
+    /// Does not check that `topics[0]` is the correct hash.
+    /// Use [`new_checked`](Self::new_checked) instead.
     fn new(
         topics: <Self::TopicList as SolType>::RustType,
         data: <Self::DataTuple<'_> as SolType>::RustType,
     ) -> Self;
 
+    /// Convert decoded rust data to the event type.
+    ///
+    /// Checks that `topics[0]` is the correct hash.
+    #[inline]
+    fn new_checked(
+        topics: <Self::TopicList as SolType>::RustType,
+        data: <Self::DataTuple<'_> as SolType>::RustType,
+    ) -> Result<Self> {
+        Self::check_signature(&topics).map(|()| Self::new(topics, data))
+    }
+
+    /// Check that the event's signature matches the given topics.
+    #[inline]
+    fn check_signature(topics: &<Self::TopicList as SolType>::RustType) -> Result<()> {
+        // Overridden for non-anonymous events in `sol!`.
+        let _ = topics;
+        Ok(())
+    }
+
     /// Tokenize the event's non-indexed parameters.
     fn tokenize_body(&self) -> Self::DataToken<'_>;
 
@@ -110,14 +132,10 @@ pub trait SolEvent: Sized {
 
     /// Encode the topics of this event into a fixed-size array.
     ///
-    /// # Panics
-    ///
-    /// This method will panic if `LEN` is not equal to
-    /// `Self::TopicList::COUNT`.
+    /// This method will not compile if `LEN` is not equal to `Self::TopicList::COUNT`.
     #[inline]
     fn encode_topics_array<const LEN: usize>(&self) -> [WordToken; LEN] {
-        // TODO: make this a compile-time error when `const` blocks are stable
-        assert_eq!(LEN, Self::TopicList::COUNT, "topic list length mismatch");
+        const { assert!(LEN == Self::TopicList::COUNT, "topic list length mismatch") };
         let mut out = [WordToken(B256::ZERO); LEN];
         self.encode_topics_raw(&mut out).unwrap();
         out
@@ -163,6 +181,8 @@ pub trait SolEvent: Sized {
         D: Into<WordToken>,
     {
         let topics = Self::decode_topics(topics)?;
+        // Check signature before decoding the data.
+        Self::check_signature(&topics)?;
         let body = Self::abi_decode_data(data, validate)?;
         Ok(Self::new(topics, body))
     }

crates/sol-types/src/types/event/topic_list.rs

@@ -47,10 +47,9 @@ macro_rules! impl_topic_list_tuples {
                 I: IntoIterator<Item = D>,
                 D: Into<WordToken>
             {
-                let err = || Error::Other(Cow::Borrowed("topic list length mismatch"));
                 let mut iter = topics.into_iter();
                 Ok(($(
-                    <$t>::detokenize(iter.next().ok_or_else(err)?.into()),
+                    <$t>::detokenize(iter.next().ok_or_else(length_mismatch)?.into()),
                 )*))
             }
         }
@@ -77,3 +76,8 @@ impl_topic_list_tuples! {
     3 => 'a T, 'b U, 'c V;
     4 => 'a T, 'b U, 'c V, 'd W;
 }
+
+#[cold]
+const fn length_mismatch() -> Error {
+    Error::Other(Cow::Borrowed("topic list length mismatch"))
+}

crates/sol-types/tests/macros/sol/mod.rs

@@ -1148,3 +1148,26 @@ fn event_indexed_elementary_arrays() {
     assert_eq!(AddrUdvtDynArray::SIGNATURE, "AddrUdvtDynArray(address[])");
     let _ = AddrUdvtDynArray { y: B256::ZERO };
 }
+
+// https://github.com/alloy-rs/core/issues/589
+#[test]
+#[allow(clippy::assertions_on_constants)]
+fn event_check_signature() {
+    sol! {
+        #[derive(Debug)]
+        event MyEvent();
+        event MyEventAnonymous() anonymous;
+    }
+
+    let no_topics: [B256; 0] = [];
+
+    assert!(!MyEvent::ANONYMOUS);
+    let e = MyEvent::decode_raw_log(no_topics, &[], false).unwrap_err();
+    assert_eq!(e.to_string(), "topic list length mismatch");
+    let e = MyEvent::decode_raw_log([B256::ZERO], &[], false).unwrap_err();
+    assert!(e.to_string().contains("invalid signature hash"), "{e:?}");
+    let MyEvent {} = MyEvent::decode_raw_log([MyEvent::SIGNATURE_HASH], &[], false).unwrap();
+
+    assert!(MyEventAnonymous::ANONYMOUS);
+    let MyEventAnonymous {} = MyEventAnonymous::decode_raw_log(no_topics, &[], false).unwrap();
+}