nghttpx: Use BlockAllocator to encode alt-svc token

src/shrpx_https_upstream.cc

@@ -960,8 +960,10 @@ std::unique_ptr<Downstream> HttpsUpstream::pop_downstream() {
 }
 
 namespace {
-void write_altsvc(DefaultMemchunks *buf, const AltSvc &altsvc) {
-  buf->append(util::percent_encode_token(altsvc.protocol_id));
+void write_altsvc(DefaultMemchunks *buf, BlockAllocator &balloc,
+                  const AltSvc &altsvc) {
+  buf->append(
+      util::percent_encode_token(balloc, StringRef{altsvc.protocol_id}));
   buf->append("=\"");
   buf->append(util::quote_string(altsvc.host));
   buf->append(":");
@@ -1073,10 +1075,10 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
       buf->append("Alt-Svc: ");
 
       auto &altsvcs = httpconf.altsvcs;
-      write_altsvc(buf, altsvcs[0]);
+      write_altsvc(buf, downstream->get_block_allocator(), altsvcs[0]);
       for (size_t i = 1; i < altsvcs.size(); ++i) {
         buf->append(", ");
-        write_altsvc(buf, altsvcs[i]);
+        write_altsvc(buf, downstream->get_block_allocator(), altsvcs[i]);
       }
       buf->append("\r\n");
     }

src/util.cc

@@ -131,11 +131,10 @@ bool in_attr_char(char c) {
          std::find(std::begin(bad), std::end(bad), c) == std::end(bad);
 }
 
-std::string percent_encode_token(const std::string &target) {
-  std::string dest;
-
-  dest.resize(target.size() * 3);
-  auto p = std::begin(dest);
+StringRef percent_encode_token(BlockAllocator &balloc,
+                               const StringRef &target) {
+  auto iov = make_byte_ref(balloc, target.size() * 3 + 1);
+  auto p = iov.base;
 
   for (auto first = std::begin(target); first != std::end(target); ++first) {
     uint8_t c = *first;
@@ -149,8 +148,10 @@ std::string percent_encode_token(const std::string &target) {
     *p++ = UPPER_XDIGITS[c >> 4];
     *p++ = UPPER_XDIGITS[(c & 0x0f)];
   }
-  dest.resize(p - std::begin(dest));
-  return dest;
+
+  *p = '\0';
+
+  return StringRef{iov.base, p};
 }
 
 uint32_t hex_to_uint(char c) {

src/util.h

@@ -129,7 +129,7 @@ std::string percent_decode(InputIt first, InputIt last) {
 StringRef percent_decode(BlockAllocator &balloc, const StringRef &src);
 
 // Percent encode |target| if character is not in token or '%'.
-std::string percent_encode_token(const std::string &target);
+StringRef percent_encode_token(BlockAllocator &balloc, const StringRef &target);
 
 // Returns quotedString version of |target|.  Currently, this function
 // just replace '"' with '\"'.

src/util_test.cc

@@ -134,10 +134,15 @@ void test_util_to_token68(void) {
 }
 
 void test_util_percent_encode_token(void) {
-  CU_ASSERT("h2" == util::percent_encode_token("h2"));
-  CU_ASSERT("h3~" == util::percent_encode_token("h3~"));
-  CU_ASSERT("100%25" == util::percent_encode_token("100%"));
-  CU_ASSERT("http%202" == util::percent_encode_token("http 2"));
+  BlockAllocator balloc(4096, 4096);
+  CU_ASSERT("h2" ==
+            util::percent_encode_token(balloc, StringRef::from_lit("h2")));
+  CU_ASSERT("h3~" ==
+            util::percent_encode_token(balloc, StringRef::from_lit("h3~")));
+  CU_ASSERT("100%25" ==
+            util::percent_encode_token(balloc, StringRef::from_lit("100%")));
+  CU_ASSERT("http%202" ==
+            util::percent_encode_token(balloc, StringRef::from_lit("http 2")));
 }
 
 void test_util_percent_encode_path(void) {