From e7b70212da546c47d1cb4b701bb36d35e1541894 Mon Sep 17 00:00:00 2001
From: Edward Houston <ehouston@blockstream.com>
Date: Fri, 7 Aug 2026 12:34:23 +0200
Subject: [PATCH] Add TooManyUtxos error kind for utxos-limit failures

The UTXO set computation in utxo_delta reused ErrorKind::TooPopular, whose
display string is "Too many history entries". That message names the wrong
limit: the check fires when the UTXO set exceeds utxos-limit during history
replay, independent of history entry count. On deployments where
electrum-txs-limit is raised but utxos-limit is not, an address could serve
its full history while /address/:addr/utxo and listunspent failed with a
message blaming history size.

Raise a distinct TooManyUtxos kind ("Too many unspent outputs") from
utxo_delta and map it to the same Electrum BadRequest code, leaving
TooPopular for the Electrum history checks.

Fixes #242
---
 src/electrum/server.rs  | 2 +-
 src/errors.rs           | 5 +++++
 src/new_index/schema.rs | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/electrum/server.rs b/src/electrum/server.rs
index 6887ccb98..fe537f813 100644
--- a/src/electrum/server.rs
+++ b/src/electrum/server.rs
@@ -106,7 +106,7 @@ impl JsonRpcV2Error {
 fn jsonrpc_code(e: &Error) -> JsonRpcV2Error {
     match e.kind() {
         ErrorKind::InvalidParams(_) => JsonRpcV2Error::InvalidParams,
-        ErrorKind::TooPopular => JsonRpcV2Error::BadRequest,
+        ErrorKind::TooPopular | ErrorKind::TooManyUtxos => JsonRpcV2Error::BadRequest,
         ErrorKind::RpcError(..) => JsonRpcV2Error::DaemonError,
         _ => JsonRpcV2Error::InternalError,
     }
diff --git a/src/errors.rs b/src/errors.rs
index dbe5f1b2d..fadc6f9ca 100644
--- a/src/errors.rs
+++ b/src/errors.rs
@@ -24,6 +24,11 @@ error_chain! {
             display("Too many history entries")
         }
 
+        TooManyUtxos {
+            description("Too many unspent outputs")
+            display("Too many unspent outputs")
+        }
+
         InvalidParams(msg: String) {
             description("Invalid RPC params")
             display("{}", msg)
diff --git a/src/new_index/schema.rs b/src/new_index/schema.rs
index 8807aca39..6ee9b8732 100644
--- a/src/new_index/schema.rs
+++ b/src/new_index/schema.rs
@@ -872,7 +872,7 @@ impl ChainQuery {
 
             // abort if the utxo set size excedees the limit at any point in time
             if utxos.len() > limit {
-                bail!(ErrorKind::TooPopular)
+                bail!(ErrorKind::TooManyUtxos)
             }
         }