[Feature] Add sampler custom logits processor (#2396)

Signed-off-by: Hongpeng Guo <hpguo@anyscale.com>

python/sglang/srt/server_args.py

@@ -159,6 +159,9 @@ class ServerArgs:
     enable_memory_saver: bool = False
     allow_auto_truncate: bool = False
 
+    # Custom logit processor
+    enable_custom_logit_processor: bool = False
+
     def __post_init__(self):
         # Set missing default values
         if self.tokenizer_path is None:
@@ -865,6 +868,11 @@ class ServerArgs:
             action="store_true",
             help="Allow automatically truncating requests that exceed the maximum input length instead of returning an error.",
         )
+        parser.add_argument(
+            "--enable-custom-logit-processor",
+            action="store_true",
+            help="Enable users to pass custom logit processors to the server (disabled by default for security)",
+        )
 
     @classmethod
     def from_cli_args(cls, args: argparse.Namespace):