1 files changed, 25 insertions, 6 deletions

diff --git a/networking/httpd.c b/networking/httpd.c
index a1f841aa8..94f7297ad 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -215,6 +215,16 @@
 //config:       Makes httpd send files using GZIP content encoding if the
 //config:       client supports it and a pre-compressed <file>.gz exists.
 //config:
+//config:config FEATURE_HTTPD_LAST_MODIFIED
+//config:       bool "Add Last-Modified header to response"
+//config:       default y
+//config:       depends on HTTPD
+//config:       help
+//config:       The Last-Modified header is used for cache validation.
+//config:       The client sends last seen mtime to server in If-Modified-Since.
+//config:       Both headers MUST be an RFC 1123 formatted, which is hard to parse.
+//config:       Use ETag header instead.
+//config:
 //config:config FEATURE_HTTPD_DATE
 //config:       bool "Add Date header to response"
 //config:       default y
@@ -1046,11 +1056,12 @@ static void log_and_exit(void)
  */
 static void send_headers(unsigned responseNum)
 {
+#if ENABLE_FEATURE_HTTPD_DATE || ENABLE_FEATURE_HTTPD_LAST_MODIFIED
         static const char RFC1123FMT[] ALIGN1 = "%a, %d %b %Y %H:%M:%S GMT";
         /* Fixed size 29-byte string. Example: Sun, 06 Nov 1994 08:49:37 GMT */
         char date_str[40]; /* using a bit larger buffer to paranoia reasons */
-
         struct tm tm;
+#endif
         const char *responseString = "";
         const char *infoString = NULL;
 #if ENABLE_FEATURE_HTTPD_ERROR_PAGES
@@ -1058,7 +1069,6 @@ static void send_headers(unsigned responseNum)
 #endif
         unsigned len;
         unsigned i;
-        time_t timer = time(NULL);
 
         for (i = 0; i < ARRAY_SIZE(http_response_type); i++) {
                 if (http_response_type[i] == responseNum) {
@@ -1079,11 +1089,13 @@ static void send_headers(unsigned responseNum)
          * always fit into those kbytes.
          */
 
+        {
 #if ENABLE_FEATURE_HTTPD_DATE
-        strftime(date_str, sizeof(date_str), RFC1123FMT, gmtime_r(&timer, &tm));
-        /* ^^^ using gmtime_r() instead of gmtime() to not use static data */
+                time_t timer = time(NULL);
+                strftime(date_str, sizeof(date_str), RFC1123FMT, gmtime_r(&timer, &tm));
+                /* ^^^ using gmtime_r() instead of gmtime() to not use static data */
 #endif
-        len = sprintf(iobuf,
+                len = sprintf(iobuf,
                         "HTTP/1.1 %u %s\r\n"
 #if ENABLE_FEATURE_HTTPD_DATE
                         "Date: %s\r\n"
@@ -1093,7 +1105,8 @@ static void send_headers(unsigned responseNum)
 #if ENABLE_FEATURE_HTTPD_DATE
                         ,date_str
 #endif
-        );
+                );
+        }
 
         if (responseNum != HTTP_OK || found_mime_type) {
                 len += sprintf(iobuf + len,
@@ -1145,7 +1158,9 @@ static void send_headers(unsigned responseNum)
 #endif
 
         if (file_size != -1) {    /* file */
+#if ENABLE_FEATURE_HTTPD_LAST_MODIFIED
                 strftime(date_str, sizeof(date_str), RFC1123FMT, gmtime_r(&last_mod, &tm));
+#endif
 #if ENABLE_FEATURE_HTTPD_RANGES
                 if (responseNum == HTTP_PARTIAL_CONTENT) {
                         len += sprintf(iobuf + len,
@@ -1190,7 +1205,9 @@ static void send_headers(unsigned responseNum)
 #if ENABLE_FEATURE_HTTPD_RANGES
                         "Accept-Ranges: bytes\r\n"
 #endif
+#if ENABLE_FEATURE_HTTPD_LAST_MODIFIED
                         "Last-Modified: %s\r\n"
+#endif
         /* Because of 4.4 (5), we can forgo sending of "Content-Length"
          * since we close connection afterwards, but it helps clients
          * to e.g. estimate download times, show progress bars etc.
@@ -1198,7 +1215,9 @@ static void send_headers(unsigned responseNum)
          * but de-facto standard is to send it (see comment below).
          */
                         "Content-Length: %"OFF_FMT"u\r\n",
+#if ENABLE_FEATURE_HTTPD_LAST_MODIFIED
                                 date_str,
+#endif
                                 file_size
                 );
         }