From e8621536577d1bc1060e293a19beb77f443f7d9c Mon Sep 17 00:00:00 2001
From: Chunting Gu <sprinfall@gmail.com>
Date: Mon, 5 Nov 2018 13:34:18 +0800
Subject: [PATCH] Add Server and Date fields to HTTP header of response.

---
 webcc/http_response.cc |  7 +++++++
 webcc/logger.cc        | 24 ++++++++++--------------
 webcc/utility.cc       |  9 +++++++++
 webcc/utility.h        |  5 +++++
 4 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/webcc/http_response.cc b/webcc/http_response.cc
index aec347a..71aecf3 100644
--- a/webcc/http_response.cc
+++ b/webcc/http_response.cc
@@ -1,5 +1,7 @@
 #include "webcc/http_response.h"
 
+#include "webcc/utility.h"
+
 namespace webcc {
 
 namespace status_strings {
@@ -57,6 +59,11 @@ const std::string& ToString(int status) {
 
 void HttpResponse::Make() {
   start_line_ = status_strings::ToString(status_);
+
+  // NOTE: C++11 requires a space between literal and string macro.
+  SetHeader("Server", "Webcc/" WEBCC_VERSION);
+
+  SetHeader("Date", GetHttpDateTimestamp());
 }
 
 HttpResponse HttpResponse::Fault(HttpStatus::Enum status) {
diff --git a/webcc/logger.cc b/webcc/logger.cc
index d351e80..d5062dd 100644
--- a/webcc/logger.cc
+++ b/webcc/logger.cc
@@ -6,6 +6,7 @@
 #include <chrono>
 #include <cstdarg>
 #include <ctime>
+#include <iomanip>  // for put_time
 #include <mutex>
 #include <sstream>
 #include <string>
@@ -115,28 +116,23 @@ void LogInit(const std::string& dir, int modes) {
 }
 
 static std::string GetTimestamp() {
-  using namespace std::chrono;
+  auto now = std::chrono::system_clock::now();
+  std::time_t t = std::chrono::system_clock::to_time_t(now);
 
-  auto now = system_clock::now();
-  std::time_t now_c = system_clock::to_time_t(now);
-  std::tm* now_tm = std::localtime(&now_c);
-
-  char buf[20];
-  std::strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", now_tm);
-
-  std::string timestamp(buf);
+  std::stringstream ss;
+  ss << std::put_time(std::localtime(&t), "%Y-%m-%d %H:%M:%S");
 
-  milliseconds milli_seconds = duration_cast<milliseconds>(
-      now.time_since_epoch());
+  std::chrono::milliseconds milli_seconds =
+      std::chrono::duration_cast<std::chrono::milliseconds>(
+          now.time_since_epoch());
   std::string micro_seconds_str = std::to_string(milli_seconds.count() % 1000);
   while (micro_seconds_str.size() < 3) {
     micro_seconds_str = "0" + micro_seconds_str;
   }
 
-  timestamp.append(".");
-  timestamp.append(micro_seconds_str);
+  ss << "." << micro_seconds_str;
 
-  return timestamp;
+  return ss.str();
 }
 
 void LogWrite(int level, const char* file, int line, const char* format, ...) {
diff --git a/webcc/utility.cc b/webcc/utility.cc
index ae30880..1c8d676 100644
--- a/webcc/utility.cc
+++ b/webcc/utility.cc
@@ -1,6 +1,8 @@
 #include "webcc/utility.h"
 
 #include <algorithm>
+#include <ctime>
+#include <iomanip>  // for put_time
 #include <ostream>
 #include <sstream>
 
@@ -55,4 +57,11 @@ std::string EndpointToString(const boost::asio::ip::tcp::endpoint& endpoint) {
   return ss.str();
 }
 
+std::string GetHttpDateTimestamp() {
+  std::time_t t = std::time(nullptr);
+  std::stringstream ss;
+  ss << std::put_time(std::gmtime(&t), "%a, %d %b %Y %H:%M:%S") << " GMT";
+  return ss.str();
+}
+
 }  // namespace webcc
diff --git a/webcc/utility.h b/webcc/utility.h
index 324090f..ec643e4 100644
--- a/webcc/utility.h
+++ b/webcc/utility.h
@@ -22,6 +22,11 @@ void PrintEndpoints(
 
 std::string EndpointToString(const boost::asio::ip::tcp::endpoint& endpoint);
 
+// Get the timestamp for HTTP Date header field.
+// E.g., Wed, 21 Oct 2015 07:28:00 GMT
+// See: https://tools.ietf.org/html/rfc7231#section-7.1.1.2
+std::string GetHttpDateTimestamp();
+
 }  // namespace webcc
 
 #endif  // WEBCC_UTILITY_H_