Include a Date: response header for rejected HTTP1 requests

omoerbeek · omoerbeek · commit 6a4965862be7 · 2025-10-27T10:33:28.000+01:00
This allows OpenBSD ntpd time constraint retrieval to work properly
with nghttp2 incoming DoH.

Note that requests having no alpn data do not appear in any stats.
Should that be changed?

Signed-off-by: Otto Moerbeek &lt;otto.moerbeek@open-xchange.com&gt;
diff --git a/pdns/dnsdistdist/dnsdist-nghttp2-in.cc b/pdns/dnsdistdist/dnsdist-nghttp2-in.cc
@@ -282,8 +282,20 @@ bool IncomingHTTP2Connection::checkALPN()
     ++d_ci.cs->dohFrontend->d_http1Stats.d_nbQueries;
   }
 
-  const std::string data("HTTP/1.1 400 Bad Request\r\nConnection: Close\r\n\r\n<html><body>This server implements RFC 8484 - DNS Queries over HTTP, and requires HTTP/2 in accordance with section 5.2 of the RFC.</body></html>\r\n");
-  d_out.insert(d_out.end(), data.begin(), data.end());
+  static const std::string data0("HTTP/1.1 400 Bad Request\r\nConnection: Close\r\n");
+
+  std::array<char, 40> data1{};
+  static const std::string dateformat("Date: %a, %d %h %Y %T GMT\r\n");
+  struct tm tmval{};
+  time_t timestamp = time(nullptr);
+  size_t len = strftime(data1.data(), data1.size(), dateformat.data(), gmtime_r(&timestamp, &tmval));
+  assert(len != 0);
+
+  static const std::string data2("\r\n<html><body>This server implements RFC 8484 - DNS Queries over HTTP, and requires HTTP/2 in accordance with section 5.2 of the RFC.</body></html>\r\n");
+
+  d_out.insert(d_out.end(), data0.begin(), data0.end());
+  d_out.insert(d_out.end(), data1.begin(), data1.end());
+  d_out.insert(d_out.end(), data2.begin(), data2.end());
   writeToSocket(false);
 
   vinfolog("DoH connection from %s expected ALPN value 'h2', got '%s'", d_ci.remote.toStringWithPort(), std::string(protocols.begin(), protocols.end()));
