etag in res.sendFile

include/expresso/helpers/response.h

@@ -5,6 +5,7 @@
 
 #include <brewtils/os.h>
 #include <brewtils/sys.h>
+#include <zippuccino/crc.h>
 
 namespace expresso {
 
@@ -14,6 +15,8 @@ static const short CHUNK_SIZE = 1024;
 
 std::string getAvailableFile(const std::string &path);
 
+const std::string generateETag(const std::string &data);
+
 bool sendChunkedData(const int &socket, const std::string &data);
 
 bool sendFileInChunks(const int &socket, const std::string &path);

src/core/response.cpp

@@ -89,6 +89,7 @@ void expresso::core::Response::sendFile(const std::string &path, int64_t start,
   this->set("content-type", brewtils::os::file::getMimeType(fileName));
   this->set("content-disposition", "inline; filename=\"" + fileName + "\"");
   this->set("accept-ranges", "bytes");
+  this->set("etag", expresso::helpers::generateETag(availableFile));
 
   if (!isPartial) {
     start = 0;

src/helpers/response.cpp

@@ -18,6 +18,14 @@ std::string expresso::helpers::getAvailableFile(const std::string &path) {
   return "";
 }
 
+const std::string expresso::helpers::generateETag(const std::string &data) {
+  const std::string availableFile = expresso::helpers::getAvailableFile(data);
+  uint32_t crc = zippuccino::crc::compute(availableFile);
+  std::ostringstream etag;
+  etag << "\"" << std::hex << std::setw(8) << std::setfill('0') << crc << "\"";
+  return etag.str();
+}
+
 bool expresso::helpers::sendChunkedData(const int &socket,
                                         const std::string &data) {
   std::ostringstream dataSizeHex;