Change to HTTP standard headers

sanic/response.py

@@ -62,6 +62,7 @@ class BaseHTTPResponse:
         "status",
         "headers",
         "_cookies",
+        "auto_content_length",
     )
 
     _dumps = json_dumps
@@ -74,6 +75,7 @@ def __init__(self):
         self.status: int = None
         self.headers = Header({})
         self._cookies: Optional[CookieJar] = None
+        self.auto_content_length = False
 
     def _encode_body(self, data: Optional[AnyStr]):
         if data is None:
@@ -153,6 +155,8 @@ async def send(
             if hasattr(data, "encode")
             else data or b""
         )
+        if self.auto_content_length and "content-length" not in self.headers:
+            self.headers["content-length"] = len(data)
         await self.stream.send(data, end_stream=end_stream)
 
 
@@ -178,6 +182,7 @@ def __init__(
         status: int = 200,
         headers: Optional[Union[Header, Dict[str, str]]] = None,
         content_type: Optional[str] = None,
+        auto_content_length: bool = False,
     ):
         super().__init__()
 
@@ -186,6 +191,7 @@ def __init__(
         self.status = status
         self.headers = Header(headers or {})
         self._cookies = None
+        self.auto_content_length = auto_content_length
 
     async def eof(self):
         await self.send("", True)
@@ -337,12 +343,11 @@ async def file(
             last_modified = stat.st_mtime
         if not max_age:
             max_age = 10  # Should change this (default) value to configable?
-        headers.setdefault("file_size", stat.st_size)
 
     if last_modified:
-        headers.setdefault("last_modified", last_modified)
+        headers.setdefault("last-modified", last_modified)
     if max_age:
-        headers.setdefault("max_age", max_age)
+        headers.setdefault("cache-control", f"max-age={max_age}")
 
     filename = filename or path.split(location)[-1]
 
@@ -363,6 +368,7 @@ async def file(
         status=status,
         headers=headers,
         content_type=mime_type,
+        auto_content_length=True,
     )