fix(http2): add Date header if not present for HTTP2 server responses

src/proto/h1/date.rs

@@ -2,6 +2,7 @@ use std::cell::RefCell;
 use std::fmt::{self, Write};
 use std::str;
 
+use http::header::HeaderValue;
 use time::{self, Duration};
 
 // "Sun, 06 Nov 1994 08:49:37 GMT".len()
@@ -19,6 +20,15 @@ pub fn update() {
     })
 }
 
+pub(crate) fn update_and_header_value() -> HeaderValue {
+    CACHED.with(|cache| {
+        let mut cache = cache.borrow_mut();
+        cache.check();
+        HeaderValue::from_bytes(cache.buffer())
+            .expect("Date format should be valid HeaderValue")
+    })
+}
+
 struct CachedDate {
     bytes: [u8; DATE_VALUE_LENGTH],
     pos: usize,

src/proto/h1/mod.rs

@@ -11,7 +11,7 @@ pub use self::io::Cursor; //TODO: move out of h1::io
 pub use self::io::MINIMUM_MAX_BUFFER_SIZE;
 
 mod conn;
-mod date;
+pub(super) mod date;
 mod decode;
 pub(crate) mod dispatch;
 mod encode;

src/proto/h2/server.rs

@@ -193,6 +193,15 @@ where
                     let (head, body) = res.into_parts();
                     let mut res = ::http::Response::from_parts(head, ());
                     super::strip_connection_headers(res.headers_mut(), false);
+
+                    // set Date header if it isn't already set...
+                    res
+                        .headers_mut()
+                        .entry(::http::header::DATE)
+                        .expect("DATE is a valid HeaderName")
+                        .or_insert_with(::proto::h1::date::update_and_header_value);
+
+                    // automatically set Content-Length from body...
                     if let Some(len) = body.content_length() {
                         headers::set_content_length_if_missing(res.headers_mut(), len);
                     }