feat(provider): check for serde error with missing req id (#1910)

ethers-providers/src/transports/retry.rs

@@ -4,7 +4,7 @@
 use super::{common::JsonRpcError, http::ClientError};
 use crate::{provider::ProviderError, JsonRpcClient};
 use async_trait::async_trait;
-use serde::{de::DeserializeOwned, Serialize};
+use serde::{de::DeserializeOwned, Deserialize, Serialize};
 use std::{
     fmt::Debug,
     sync::atomic::{AtomicU32, Ordering},
@@ -347,11 +347,8 @@ pub struct HttpRateLimitRetryPolicy;
 
 impl RetryPolicy<ClientError> for HttpRateLimitRetryPolicy {
     fn should_retry(&self, error: &ClientError) -> bool {
-        match error {
-            ClientError::ReqwestError(err) => {
-                err.status() == Some(http::StatusCode::TOO_MANY_REQUESTS)
-            }
-            ClientError::JsonRpcError(JsonRpcError { code, message, .. }) => {
+        fn should_retry_json_rpc_error(err: &JsonRpcError) -> bool {
+            let JsonRpcError { code, message, .. } = err;
             // alchemy throws it this way
             if *code == 429 {
                 return true
@@ -370,7 +367,25 @@ impl RetryPolicy<ClientError> for HttpRateLimitRetryPolicy {
                 _ => false,
             }
         }
-            _ => false,
+
+        match error {
+            ClientError::ReqwestError(err) => {
+                err.status() == Some(http::StatusCode::TOO_MANY_REQUESTS)
+            }
+            ClientError::JsonRpcError(err) => should_retry_json_rpc_error(err),
+            ClientError::SerdeJson { text, .. } => {
+                // some providers send invalid JSON RPC in the error case (no `id:u64`), but the
+                // text should be a `JsonRpcError`
+                #[derive(Deserialize)]
+                struct Resp {
+                    error: JsonRpcError,
+                }
+
+                if let Ok(resp) = serde_json::from_str::<Resp>(text) {
+                    return should_retry_json_rpc_error(&resp.error)
+                }
+                false
+            }
         }
     }
 
@@ -526,4 +541,17 @@ mod tests {
         let should_retry = HttpRateLimitRetryPolicy::default().should_retry(&err);
         assert!(should_retry);
     }
+
+    #[test]
+    fn test_rate_limit_omitted_id() {
+        let s = r#"{"jsonrpc":"2.0","error":{"code":-32016,"message":"Your IP has exceeded its requests per second capacity. To increase your rate limits, please sign up for a free Alchemy account at https://www.alchemy.com/optimism."},"id":null}"#;
+
+        let err = ClientError::SerdeJson {
+            err: serde::de::Error::custom("unexpected notification over HTTP transport"),
+            text: s.to_string(),
+        };
+
+        let should_retry = HttpRateLimitRetryPolicy::default().should_retry(&err);
+        assert!(should_retry);
+    }
 }