feat(unionlabs): parse wasm client type from wasm blob

unionlabs · Sep 26, 2023 · 4b01ca4 · 4b01ca4
1 parent 7c3c9bb
commit 4b01ca4
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diff --git a/Cargo.lock b/Cargo.lock
diff --git a/lib/unionlabs/Cargo.toml b/lib/unionlabs/Cargo.toml
@@ -39,6 +39,10 @@ ethers-core = { version = "2.0.8", optional = true }
 serde_json = { version = "1.0.96", optional = true }
 bitvec = "1.0.1"
 
+wasmparser = { version = "0.113" }
+
+paste = { version = "1.0" }
+
 [dev-dependencies]
 rand = "0.8.5"
 serde_json = "1.0.96"

diff --git a/lib/unionlabs/src/lib.rs b/lib/unionlabs/src/lib.rs
@@ -654,3 +654,63 @@ impl<'de> Deserialize<'de> for EmptyString {
 impl traits::Id for EmptyString {
     type FromStrErr = EmptyStringParseError;
 }
+
+pub use paste::paste;
+
+#[macro_export]
+macro_rules! export_wasm_client_type {
+    ($type:ident) => {
+        const _: unionlabs::WasmClientType = unionlabs::WasmClientType::$type;
+        unionlabs::paste! {
+            #[no_mangle]
+            #[used]
+            static [ <WASM_CLIENT_TYPE_ $type> ]: u8 = 0;
+        }
+        #[no_mangle]
+        #[used]
+        static WASM_CLIENT_TYPE_DEFINED: u8 = 0;
+    };
+}
+
+/// This type is used to discrimate 08-wasm light clients.
+/// We need to be able to determine the light client from the light client code itself (not instantiated yet).
+/// Light clients supported by voyager must export a `#[no_mangle] static WASM_CLIENT_TYPE: WasmClientType = WasmClientType::...` variable.
+#[derive(Debug, PartialEq, Eq)]
+pub enum WasmClientType {
+    EthereumMinimal,
+    EthereumMainnet,
+    Cometbls,
+}
+
+impl TryFrom<&[u8]> for WasmClientType {
+    type Error = ();
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
+        let wasm_type_name = wasmparser::Parser::new(0)
+            .parse_all(value)
+            .find_map(|payload| {
+                payload.ok().and_then(|payload| match payload {
+                    wasmparser::Payload::ExportSection(e) => Some(e),
+                    _ => None,
+                })
+            })
+            .and_then(|exports| {
+                exports.into_iter().find_map(|export| {
+                    export.ok().and_then(|export| {
+                        if let Some(type_name) = export.name.strip_prefix("WASM_CLIENT_TYPE_")
+                        {
+                            Some(type_name)
+                        } else {
+                            None
+                        }
+                    })
+                })
+            })
+            .ok_or(())?;
+        Ok(match wasm_type_name {
+            "EthereumMinimal" => WasmClientType::EthereumMinimal,
+            "EthereumMainnet" => WasmClientType::EthereumMainnet,
+            "Cometbls" => WasmClientType::Cometbls,
+            _ => Err(())?,
+        })
+    }
+}