From 1fb06bbc10a7bd621c694a33137cf16b23b07a02 Mon Sep 17 00:00:00 2001
From: Sam Bull <git@sambull.org>
Date: Sun, 6 Aug 2023 00:33:16 +0100
Subject: [PATCH] Fix error pointer on linebreaks (#7480)

Fixes #7468.
---
 CHANGES/7468.bugfix       |  1 +
 aiohttp/_http_parser.pyx  |  4 ++--
 tests/test_http_parser.py | 22 +++++++++++++++++++++-
 3 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 CHANGES/7468.bugfix

diff --git a/CHANGES/7468.bugfix b/CHANGES/7468.bugfix
new file mode 100644
index 00000000000..3f9c256ca0c
--- /dev/null
+++ b/CHANGES/7468.bugfix
@@ -0,0 +1 @@
+Fixed output of parsing errors on `\n`. -- by :user:`Dreamsorcerer`
diff --git a/aiohttp/_http_parser.pyx b/aiohttp/_http_parser.pyx
index 4f39dd0c978..8b7d48245d2 100644
--- a/aiohttp/_http_parser.pyx
+++ b/aiohttp/_http_parser.pyx
@@ -548,8 +548,8 @@ cdef class HttpParser:
                 else:
                     after = cparser.llhttp_get_error_pos(self._cparser)
                     before = data[:after - <char*>self.py_buf.buf]
-                    after_b = after.split(b"\n", 1)[0]
-                    before = before.rsplit(b"\n", 1)[-1]
+                    after_b = after.split(b"\r\n", 1)[0]
+                    before = before.rsplit(b"\r\n", 1)[-1]
                     data = before + after_b
                     pointer = " " * (len(repr(before))-1) + "^"
                     ex = parser_error_from_errno(self._cparser, data, pointer)
diff --git a/tests/test_http_parser.py b/tests/test_http_parser.py
index 8113fb94dd1..18706a3bae2 100644
--- a/tests/test_http_parser.py
+++ b/tests/test_http_parser.py
@@ -131,7 +131,27 @@ def test_invalid_character(loop: Any, protocol: Any, request: Any) -> None:
     error_detail = re.escape(
         r""":
 
-    b'Set-Cookie: abc\x01def\r'
+    b'Set-Cookie: abc\x01def'
+                     ^"""
+    )
+    with pytest.raises(http_exceptions.BadHttpMessage, match=error_detail):
+        parser.feed_data(text)
+
+
+@pytest.mark.skipif(NO_EXTENSIONS, reason="Only tests C parser.")
+def test_invalid_linebreak(loop: Any, protocol: Any, request: Any) -> None:
+    parser = HttpRequestParserC(
+        protocol,
+        loop,
+        2**16,
+        max_line_size=8190,
+        max_field_size=8190,
+    )
+    text = b"GET /world HTTP/1.1\r\nHost: 127.0.0.1\n\r\n"
+    error_detail = re.escape(
+        r""":
+
+    b'Host: 127.0.0.1\n'
                      ^"""
     )
     with pytest.raises(http_exceptions.BadHttpMessage, match=error_detail):