nghttpx: Use StringRef for AltSvc fields

src/shrpx_config.cc

@@ -2376,16 +2376,16 @@ int parse_config(Config *config, int optid, const StringRef &opt,
 
     AltSvc altsvc{};
 
-    altsvc.protocol_id = tokens[0].str();
+    altsvc.protocol_id = make_string_ref(config->balloc, tokens[0]);
 
     altsvc.port = port;
-    altsvc.service = tokens[1].str();
+    altsvc.service = make_string_ref(config->balloc, tokens[1]);
 
     if (tokens.size() > 2) {
-      altsvc.host = tokens[2].str();
+      altsvc.host = make_string_ref(config->balloc, tokens[2]);
 
       if (tokens.size() > 3) {
-        altsvc.origin = tokens[3].str();
+        altsvc.origin = make_string_ref(config->balloc, tokens[3]);
       }
     }
 

src/shrpx_config.h

@@ -337,7 +337,7 @@ enum shrpx_forwarded_node_type {
 };
 
 struct AltSvc {
-  std::string protocol_id, host, origin, service;
+  StringRef protocol_id, host, origin, service;
 
   uint16_t port;
 };

src/shrpx_https_upstream.cc

@@ -962,10 +962,9 @@ std::unique_ptr<Downstream> HttpsUpstream::pop_downstream() {
 namespace {
 void write_altsvc(DefaultMemchunks *buf, BlockAllocator &balloc,
                   const AltSvc &altsvc) {
-  buf->append(
-      util::percent_encode_token(balloc, StringRef{altsvc.protocol_id}));
+  buf->append(util::percent_encode_token(balloc, altsvc.protocol_id));
   buf->append("=\"");
-  buf->append(util::quote_string(balloc, StringRef{altsvc.host}));
+  buf->append(util::quote_string(balloc, altsvc.host));
   buf->append(':');
   buf->append(altsvc.service);
   buf->append('"');