From 14eb982db531554d557064ef10c180485e402a23 Mon Sep 17 00:00:00 2001
From: reverse <mike.chevronnet@gmail.com>
Date: Wed, 19 Aug 2026 01:13:39 +0000
Subject: [PATCH] =?UTF-8?q?multiline:=20reject=20an=20over-limit=20batch?=
 =?UTF-8?q?=20with=20a=20FAIL=20instead=20of=20silently=20dropping=20the?=
 =?UTF-8?q?=20overflowing=20lines=20=E2=80=94=20accumulate()=20dropped=20a?=
 =?UTF-8?q?=20line=20that=20exceeded=20multiline=5Fmaxbytes/maxlines=20but?=
 =?UTF-8?q?=20still=20returned=20buffered=3Dtrue,=20so=20the=20client=20be?=
 =?UTF-8?q?lieved=20a=20truncated=20message=20was=20sent=20whole;=20now=20?=
 =?UTF-8?q?overflow=20flags=20the=20batch=20and=20close()=20drops=20it=20w?=
 =?UTF-8?q?ith=20a=20standard=20FAIL?=
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---
 src/modules/multiline.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/modules/multiline.rs b/src/modules/multiline.rs
index 85d01f7..c9c6640 100644
--- a/src/modules/multiline.rs
+++ b/src/modules/multiline.rs
@@ -35,6 +35,7 @@ pub struct MlineBatch {
     pub notice: bool,
     pub parts: Vec<(String, bool)>, // (text, concat-with-previous-part)
     pub bytes: usize,
+    pub overflowed: bool, // a line exceeded the byte/line limit — reject the whole batch
 }
 
 /// uid -> its open batch. Stored in `Server.ext`.
@@ -52,6 +53,7 @@ fn open(s: &mut Server, uid: Uid, bref: &str, target: &str) {
             notice: false,
             parts: Vec::new(),
             bytes: 0,
+            overflowed: false,
         },
     );
 }
@@ -74,6 +76,10 @@ pub fn accumulate(
                 mb.notice = notice;
                 mb.bytes += text.len();
                 mb.parts.push((text.to_string(), concat));
+            } else {
+                // over the byte/line budget — flag so close() rejects the whole batch
+                // rather than silently delivering a truncated message.
+                mb.overflowed = true;
             }
             true
         }
@@ -90,6 +96,15 @@ fn close(s: &mut Server, uid: Uid, bref: &str) -> Option<(String, bool, Vec<Stri
         _ => return None,
     }
     let mb = store.0.remove(&uid)?;
+    if mb.overflowed {
+        s.fail(
+            uid,
+            "BATCH",
+            "MULTILINE_INVALID",
+            "Multiline batch exceeded the size/line limit and was dropped.",
+        );
+        return None;
+    }
     let mut lines: Vec<String> = Vec::new();
     for (text, concat) in mb.parts {
         if concat && !lines.is_empty() {