Add gitea download git diff limit

src/bot.rs

@@ -1,9 +1,11 @@
-use std::time::Duration;
-
+use futures_util::stream::TryStreamExt;
 use serde::Deserialize;
+use std::time::Duration;
+use tokio::io::AsyncReadExt;
+use tokio_util::io::StreamReader;
 
 use crate::{
-    consts::{BOT_PROCESS_MSG, REVIEW_PROMPT},
+    consts::{BOT_PROCESS_MSG, MAX_DIFF_SIZE, REVIEW_PROMPT},
     env::EnvConfig,
     errors::AppError,
     gitea::{GiteaAPI, ReviewPayload, WebhookType},
@@ -197,7 +199,18 @@ impl Bot {
 
     async fn download_git_diff(&self, url: &str) -> anyhow::Result<String> {
         let response = self.http_client.get(url).send().await?;
-        let body = response.text().await?;
-        Ok(body)
+        let stream = response.bytes_stream().map_err(std::io::Error::other);
+
+        let mut buf = Vec::with_capacity(MAX_DIFF_SIZE);
+        StreamReader::new(stream)
+            .take((MAX_DIFF_SIZE + 1) as u64)
+            .read_to_end(&mut buf)
+            .await?;
+
+        if buf.len() > MAX_DIFF_SIZE {
+            anyhow::bail!("Git diff exceeds the maximum allowed size of 1 Mo");
+        }
+
+        Ok(String::from_utf8_lossy(&buf).into_owned())
     }
 }