Add children recursive endpoint

docs/src/inscriptions/recursion.md

@@ -26,3 +26,5 @@ A few other endpoints that inscriptions may access are the following:
 - `/blockhash`: latest block hash.
 - `/blockhash/<HEIGHT>`: block hash at given block height.
 - `/blocktime`: UNIX time stamp of latest block.
+- `/children/<INSCRIPTION_ID>`: list of children that have the given
+  inscription as their parent.

src/subcommand/server.rs

@@ -210,6 +210,7 @@ impl Server {
         .route("/install.sh", get(Self::install_script))
         .route("/ordinal/:sat", get(Self::ordinal))
         .route("/output/:output", get(Self::output))
+        .route("/children/:inscription_id", get(Self::children))
         .route("/preview/:inscription_id", get(Self::preview))
         .route("/range/:start/:end", get(Self::range))
         .route("/rare.txt", get(Self::rare_txt))
@@ -833,6 +834,14 @@ impl Server {
     )
   }
 
+  async fn children(
+    Extension(index): Extension<Arc<Index>>,
+    Path(inscription_id): Path<InscriptionId>,
+  ) -> ServerResult<Json<Vec<InscriptionId>>> {
+    let children = index.get_children_by_inscription_id(inscription_id)?;
+    Ok(Json(children))
+  }
+
   async fn input(
     Extension(page_config): Extension<Arc<PageConfig>>,
     Extension(index): Extension<Arc<Index>>,
@@ -903,7 +912,7 @@ impl Server {
     );
     headers.append(
       header::CONTENT_SECURITY_POLICY,
-      HeaderValue::from_static("default-src *:*/content/ *:*/blockheight *:*/blockhash *:*/blockhash/ *:*/blocktime 'unsafe-eval' 'unsafe-inline' data: blob:"),
+      HeaderValue::from_static("default-src *:*/content/ *:*/blockheight *:*/blockhash *:*/blockhash/ *:*/blocktime *:*/children/ 'unsafe-eval' 'unsafe-inline' data: blob:"),
     );
     headers.insert(
       header::CACHE_CONTROL,
@@ -1762,6 +1771,53 @@ mod tests {
     assert_eq!(response.text().unwrap(), "1231006505");
   }
 
+  #[test]
+  fn children_endpoint() {
+    let server = TestServer::new_with_regtest_with_json_api();
+    server.mine_blocks(1);
+
+    let parent_txid = server.bitcoin_rpc_server.broadcast_tx(TransactionTemplate {
+      inputs: &[(1, 0, 0, inscription("text/plain", "hello").to_witness())],
+      ..Default::default()
+    });
+
+    server.mine_blocks(1);
+
+    let parent_inscription_id = InscriptionId {
+      txid: parent_txid,
+      index: 0,
+    };
+
+    let txid = server.bitcoin_rpc_server.broadcast_tx(TransactionTemplate {
+      inputs: &[
+        (
+          2,
+          0,
+          0,
+          Inscription {
+            content_type: Some("text/plain".into()),
+            body: Some("hello".into()),
+            parent: Some(parent_inscription_id.parent_value()),
+            unrecognized_even_field: false,
+          }
+          .to_witness(),
+        ),
+        (2, 1, 0, Default::default()),
+      ],
+      ..Default::default()
+    });
+
+    server.mine_blocks(1);
+
+    let child_inscription_id = InscriptionId { txid, index: 0 };
+
+    server.assert_response_regex(
+      format!("/inscription/{parent_inscription_id}"),
+      StatusCode::OK,
+      format!(".*[{child_inscription_id}].*"),
+    );
+  }
+
   #[test]
   fn range_end_before_range_start_returns_400() {
     TestServer::new().assert_response(

tests/server.rs

@@ -189,7 +189,7 @@ fn inscription_content() {
       .collect::<Vec<&http::HeaderValue>>(),
     &[
       "default-src 'self' 'unsafe-eval' 'unsafe-inline' data: blob:",
-      "default-src *:*/content/ *:*/blockheight *:*/blockhash *:*/blockhash/ *:*/blocktime 'unsafe-eval' 'unsafe-inline' data: blob:",
+      "default-src *:*/content/ *:*/blockheight *:*/blockhash *:*/blockhash/ *:*/blocktime *:*/children/ 'unsafe-eval' 'unsafe-inline' data: blob:",
     ]
   );
   assert_eq!(response.bytes().unwrap(), "FOO");