fuzz: fix boundary error (#179)

Co-authored-by: Marcelo Trylesinski <[email protected]>

Author: manunio

fuzz/fuzz_form.py

@@ -29,8 +29,15 @@ def parse_form_urlencoded(fdp: EnhancedDataProvider) -> None:
 
 
 def parse_multipart_form_data(fdp: EnhancedDataProvider) -> None:
-    header = {"Content-Type": "multipart/form-data; boundary=--boundary"}
-    parse_form(header, io.BytesIO(fdp.ConsumeRandomBytes()), on_field, on_file)
+    boundary = "boundary"
+    header = {"Content-Type": f"multipart/form-data; boundary={boundary}"}
+    body = (
+        f"--{boundary}\r\n"
+        f"Content-Type: multipart/form-data; boundary={boundary}\r\n\r\n"
+        f"{fdp.ConsumeRandomString()}\r\n"
+        f"--{boundary}--\r\n"
+    )
+    parse_form(header, io.BytesIO(body.encode("latin1", errors="ignore")), on_field, on_file)
 
 
 def TestOneInput(data: bytes) -> None: