3 files changed, 6 insertions, 0 deletions
diff --git a/cqrlogo.c b/cqrlogo.c
index 80b57e0..ba4481e 100644
--- a/cqrlogo.c
+++ b/cqrlogo.c
@@ -17,6 +17,7 @@ int main(int argc, char **argv) {
 	regex_t preg;
 	regmatch_t pmatch[1];
 	uint8_t https;
+	struct timeval tv;
 
 	struct cqr_png * png;
 	struct cqr_bitmap * bitmap;
@@ -104,7 +105,10 @@ int main(int argc, char **argv) {
 		/* print HTTP header */
 		fputs(CQR_HEADER_CONTENT_TYPE, stdout);
 		fputs(CQR_HEADER_CONTENT_DISPOSITION, stdout);
+		fputs(CQR_HEADER_CACHE_CONTROL, stdout);
 		fputs(CQR_HEADER_PRAGMA, stdout);
+		gettimeofday(&tv, NULL);
+		fprintf(stdout, "ETag: %lu%lu\n", tv.tv_sec, tv.tv_usec);
 		fputc('\n', stdout);
 
 		/* write PNG data to stdout */
diff --git a/cqrlogo.h b/cqrlogo.h
index 430df26..cf5db51 100644
--- a/cqrlogo.h
+++ b/cqrlogo.h
@@ -16,6 +16,7 @@
 #include <inttypes.h>
 #include <regex.h>
 #include <stdbool.h>
+#include <sys/time.h>
 
 #if HAVE_FCGI
 #include <fcgi_stdio.h>
diff --git a/lib/libcqrlogo.h b/lib/libcqrlogo.h
index eb945b1..73ce149 100644
--- a/lib/libcqrlogo.h
+++ b/lib/libcqrlogo.h
@@ -42,6 +42,7 @@ struct cqr_conf {
 	bool overwrite;
 };
 
+#define CQR_HEADER_CACHE_CONTROL	"Cache-Control: no-cache\nCache-Control: max-age=0\n"
 #define CQR_HEADER_CONTENT_TYPE		"Content-Type: image/png\n"
 #define CQR_HEADER_CONTENT_DISPOSITION	"Content-Disposition: inline; filename=\"cqrlogo.png\"\n"
 #define CQR_HEADER_PRAGMA		"Pragma: no-cache\n"