From f2e9115c0596519141b201a1025311d80e9a8730 Mon Sep 17 00:00:00 2001
From: jaceksnet <jaceks@gmail.com>
Date: Mon, 24 Jun 2019 19:59:09 +0200
Subject: [PATCH] allow use of characters out of latin-1 in multipart form
 values and filename

---
 starlette/formparsers.py  | 14 ++++++++--
 tests/test_formparsers.py | 55 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 66 insertions(+), 3 deletions(-)

diff --git a/starlette/formparsers.py b/starlette/formparsers.py
index cbbe8949..8479e0d1 100644
--- a/starlette/formparsers.py
+++ b/starlette/formparsers.py
@@ -31,6 +31,13 @@ class MultiPartMessage(Enum):
     END = 8
 
 
+def _user_safe_decode(src: bytes, codec: str) -> str:
+    try:
+        return src.decode(codec)
+    except LookupError:
+        return src.decode("latin-1")
+
+
 class FormParser:
     def __init__(
         self, headers: Headers, stream: typing.AsyncGenerator[bytes, None]
@@ -153,6 +160,9 @@ class MultiPartParser:
     async def parse(self) -> FormData:
         # Parse the Content-Type header to get the multipart boundary.
         content_type, params = parse_options_header(self.headers["Content-Type"])
+        charset = params.get(b"charset", "latin-1")
+        if type(charset) == bytes:
+            charset = charset.decode("latin-1")
         boundary = params.get(b"boundary")
 
         # Callbacks dictionary.
@@ -204,7 +214,7 @@ class MultiPartParser:
                     disposition, options = parse_options_header(content_disposition)
                     field_name = options[b"name"].decode("latin-1")
                     if b"filename" in options:
-                        filename = options[b"filename"].decode("latin-1")
+                        filename = _user_safe_decode(options[b"filename"], charset)
                         file = UploadFile(filename=filename, content_type=content_type)
                     else:
                         file = None
@@ -215,7 +225,7 @@ class MultiPartParser:
                         await file.write(message_bytes)
                 elif message_type == MultiPartMessage.PART_END:
                     if file is None:
-                        items.append((field_name, data.decode("latin-1")))
+                        items.append((field_name, _user_safe_decode(data, charset)))
                     else:
                         await file.seek(0)
                         items.append((field_name, file))
diff --git a/tests/test_formparsers.py b/tests/test_formparsers.py
index 8bc71905..c4fedeed 100644
--- a/tests/test_formparsers.py
+++ b/tests/test_formparsers.py
@@ -1,6 +1,6 @@
 import os
 
-from starlette.formparsers import UploadFile
+from starlette.formparsers import UploadFile, _user_safe_decode
 from starlette.requests import Request
 from starlette.responses import JSONResponse
 from starlette.testclient import TestClient
@@ -206,6 +206,49 @@ def test_multipart_request_mixed_files_and_data(tmpdir):
     }
 
 
+def test_multipart_request_with_charset_for_filename(tmpdir):
+    client = TestClient(app)
+    response = client.post(
+        "/",
+        data=(
+            # file
+            b"--a7f7ac8d4e2e437c877bb7b8d7cc549c\r\n"
+            b'Content-Disposition: form-data; name="file"; filename="file\xc4\x85.txt"\r\n'
+            b"Content-Type: text/plain\r\n\r\n"
+            b"<file content>\r\n"
+            b"--a7f7ac8d4e2e437c877bb7b8d7cc549c--\r\n"
+        ),
+        headers={
+            "Content-Type": "multipart/form-data; charset=utf-8; boundary=a7f7ac8d4e2e437c877bb7b8d7cc549c"
+        },
+    )
+    assert response.json() == {
+        "file": {
+            "filename": "fileą.txt",
+            "content": "<file content>",
+            "content_type": "text/plain",
+        }
+    }
+
+
+def test_multipart_request_with_encoded_value(tmpdir):
+    client = TestClient(app)
+    response = client.post(
+        "/",
+        data=(
+            b"--20b303e711c4ab8c443184ac833ab00f\r\n"
+            b"Content-Disposition: form-data; "
+            b'name="value"\r\n\r\n'
+            b"Transf\xc3\xa9rer\r\n"
+            b"--20b303e711c4ab8c443184ac833ab00f--\r\n"
+        ),
+        headers={
+            "Content-Type": "multipart/form-data; charset=utf-8; boundary=20b303e711c4ab8c443184ac833ab00f"
+        },
+    )
+    assert response.json() == {"value": "Transférer"}
+
+
 def test_urlencoded_request_data(tmpdir):
     client = TestClient(app)
     response = client.post("/", data={"some": "data"})
@@ -242,3 +285,13 @@ def test_multipart_multi_field_app_reads_body(tmpdir):
         "/", data={"some": "data", "second": "key pair"}, files=FORCE_MULTIPART
     )
     assert response.json() == {"some": "data", "second": "key pair"}
+
+
+def test_user_safe_decode_helper():
+    result = _user_safe_decode(b"\xc4\x99\xc5\xbc\xc4\x87", "utf-8")
+    assert result == "ężć"
+
+
+def test_user_safe_decode_ignores_wrong_charset():
+    result = _user_safe_decode(b"abc", "latin-8")
+    assert result == "abc"
-- 
2.47.2