Add helper template for StringRef from contiguous range

src/http2.cc

@@ -632,7 +632,7 @@ StringRef rewrite_location_uri(BlockAllocator &balloc, const StringRef &uri,
 
   *p = '\0';
 
-  return StringRef{std::span{std::ranges::begin(iov), p}};
+  return as_string_ref(std::ranges::begin(iov), p);
 }
 
 int parse_http_status_code(const StringRef &src) {
@@ -1590,7 +1590,7 @@ int construct_push_component(BlockAllocator &balloc, StringRef &scheme,
       }
       *p = '\0';
 
-      authority = StringRef{std::span{std::ranges::begin(iov), p}};
+      authority = as_string_ref(std::ranges::begin(iov), p);
     }
 
     if (u.field_set & (1 << URLPARSE_PATH)) {
@@ -1669,12 +1669,12 @@ StringRef path_join(BlockAllocator &balloc, const StringRef &base_path,
         p = std::ranges::copy(base_query, p).out;
       }
       *p = '\0';
-      return StringRef{std::span{std::ranges::begin(res), p}};
+      return as_string_ref(std::ranges::begin(res), p);
     }
     *p++ = '?';
     p = std::ranges::copy(rel_query, p).out;
     *p = '\0';
-    return StringRef{std::span{std::ranges::begin(res), p}};
+    return as_string_ref(std::ranges::begin(res), p);
   }
 
   auto first = std::ranges::begin(rel_path);
@@ -1736,7 +1736,7 @@ StringRef path_join(BlockAllocator &balloc, const StringRef &base_path,
     p = std::ranges::copy(rel_query, p).out;
   }
   *p = '\0';
-  return StringRef{std::span{std::ranges::begin(res), p}};
+  return as_string_ref(std::ranges::begin(res), p);
 }
 
 StringRef normalize_path(BlockAllocator &balloc, const StringRef &path,
@@ -1783,7 +1783,7 @@ StringRef normalize_path(BlockAllocator &balloc, const StringRef &path,
   *p = '\0';
 
   return path_join(balloc, StringRef{}, StringRef{},
-                   StringRef{std::span{std::ranges::begin(result), p}}, query);
+                   as_string_ref(std::ranges::begin(result), p), query);
 }
 
 StringRef normalize_path_colon(BlockAllocator &balloc, const StringRef &path,
@@ -1830,7 +1830,7 @@ StringRef normalize_path_colon(BlockAllocator &balloc, const StringRef &path,
   *p = '\0';
 
   return path_join(balloc, StringRef{}, StringRef{},
-                   StringRef{std::span{std::ranges::begin(result), p}}, query);
+                   as_string_ref(std::ranges::begin(result), p), query);
 }
 
 std::string normalize_path(const StringRef &path, const StringRef &query) {
@@ -1860,7 +1860,7 @@ StringRef copy_lower(BlockAllocator &balloc, const StringRef &src) {
   p = std::ranges::copy(src, p).out;
   *p = '\0';
   util::inp_strlower(std::ranges::begin(iov), p);
-  return StringRef{std::span{std::ranges::begin(iov), p}};
+  return as_string_ref(std::ranges::begin(iov), p);
 }
 
 bool contains_trailers(const StringRef &s) {
@@ -1900,7 +1900,7 @@ StringRef make_websocket_accept_token(uint8_t *dest, const StringRef &key) {
     return StringRef{};
   }
 
-  return StringRef{std::span{dest, base64::encode(h, dest)}};
+  return as_string_ref(dest, base64::encode(h, dest));
 }
 
 bool legacy_http1(int major, int minor) {

src/shrpx.cc

@@ -3942,7 +3942,7 @@ int process_options(Config *config,
     auto gen = util::make_mt19937();
     p = util::random_alpha_digit(p, p + SHRPX_OBFUSCATED_NODE_LENGTH, gen);
     *p = '\0';
-    fwdconf.by_obfuscated = StringRef{std::span{std::begin(iov), p}};
+    fwdconf.by_obfuscated = as_string_ref(std::begin(iov), p);
   }
 
   if (config->http2.upstream.debug.frame_debug) {

src/shrpx_api_downstream_connection.cc

@@ -288,8 +288,8 @@ int APIDownstreamConnection::error_method_not_allowed() {
   p -= 2;
   *p = '\0';
 
-  resp.fs.add_header_token("allow"_sr, StringRef{std::span{std::begin(iov), p}},
-                           false, -1);
+  resp.fs.add_header_token("allow"_sr, as_string_ref(std::begin(iov), p), false,
+                           -1);
   return send_reply(405, APIStatusCode::FAILURE);
 }
 
@@ -368,7 +368,7 @@ int APIDownstreamConnection::handle_backendconfig() {
   std::set<StringRef> include_set;
   std::map<StringRef, size_t> pattern_addr_indexer;
 
-  for (auto first = reinterpret_cast<const uint8_t *>(rp),
+  for (auto first = reinterpret_cast<const char *>(rp),
             last = first + req.recv_body_length;
        first != last;) {
     auto eol = std::find(first, last, '\n');
@@ -387,8 +387,8 @@ int APIDownstreamConnection::handle_backendconfig() {
       return 0;
     }
 
-    auto opt = StringRef{std::span{first, eq}};
-    auto optval = StringRef{std::span{eq + 1, eol}};
+    auto opt = StringRef{first, eq};
+    auto optval = StringRef{eq + 1, eol};
 
     auto optid = option_lookup_token(opt);
 

src/shrpx_client_handler.cc

@@ -498,7 +498,7 @@ ClientHandler::ClientHandler(Worker *worker, int fd, SSL *ssl,
                                    worker_->get_randgen());
       *p = '\0';
 
-      forwarded_for_ = StringRef{std::span{std::ranges::begin(buf), p}};
+      forwarded_for_ = as_string_ref(std::ranges::begin(buf), p);
     } else {
       init_forwarded_for(family, ipaddr_);
     }
@@ -517,7 +517,7 @@ void ClientHandler::init_forwarded_for(int family, const StringRef &ipaddr) {
     *p++ = ']';
     *p = '\0';
 
-    forwarded_for_ = StringRef{std::span{std::ranges::begin(buf), p}};
+    forwarded_for_ = as_string_ref(std::ranges::begin(buf), p);
   } else {
     // family == AF_INET or family == AF_UNIX
     forwarded_for_ = ipaddr;

src/shrpx_config.cc

@@ -384,7 +384,7 @@ HeaderRefs::value_type parse_header(BlockAllocator &balloc,
   *p = '\0';
 
   auto nv =
-    HeaderRef(StringRef{std::span{std::begin(name_iov), p}},
+    HeaderRef(as_string_ref(std::begin(name_iov), p),
               make_string_ref(balloc, StringRef{value, std::end(optarg)}));
 
   if (!nghttp2_check_header_name(nv.name.byte(), nv.name.size()) ||
@@ -787,7 +787,7 @@ std::vector<LogFragment> parse_log_format(BlockAllocator &balloc,
       std::transform(std::begin(iov), p, std::begin(iov),
                      [](auto c) { return c == '_' ? '-' : c; });
       *p = '\0';
-      res.emplace_back(type, StringRef{std::span{std::begin(iov), p}});
+      res.emplace_back(type, as_string_ref(std::begin(iov), p));
     }
   }
 
@@ -1237,7 +1237,7 @@ int parse_mapping(Config *config, DownstreamAddrConfig &addr,
       util::inp_strlower(std::begin(iov), p);
       *p++ = '/';
       *p = '\0';
-      pattern = StringRef{std::span{std::begin(iov), p}};
+      pattern = as_string_ref(std::begin(iov), p);
     } else {
       auto path = http2::normalize_path_colon(
         downstreamconf.balloc, StringRef{slash, std::end(raw_pattern)},
@@ -1249,7 +1249,7 @@ int parse_mapping(Config *config, DownstreamAddrConfig &addr,
       util::inp_strlower(std::begin(iov), p);
       p = std::copy(std::begin(path), std::end(path), p);
       *p = '\0';
-      pattern = StringRef{std::span{std::begin(iov), p}};
+      pattern = as_string_ref(std::begin(iov), p);
     }
     auto it = pattern_addr_indexer.find(pattern);
     if (it != std::end(pattern_addr_indexer)) {
@@ -1384,7 +1384,7 @@ int parse_mapping(Config *config, DownstreamAddrConfig &addr,
         auto p =
           std::reverse_copy(std::begin(host), std::end(host), std::begin(iov));
         *p = '\0';
-        auto rev_host = StringRef{std::span{std::begin(iov), p}};
+        auto rev_host = as_string_ref(std::begin(iov), p);
 
         rw_router.add_route(rev_host, wildcard_patterns.size() - 1);
       } else {

src/shrpx_downstream.cc

@@ -371,7 +371,7 @@ StringRef Downstream::assemble_request_cookie() {
     p -= 2;
   }
 
-  return StringRef{std::span{std::ranges::begin(iov), p}};
+  return as_string_ref(std::ranges::begin(iov), p);
 }
 
 uint32_t Downstream::find_affinity_cookie(const StringRef &name) {
@@ -481,7 +481,7 @@ StringRef alloc_header_name(BlockAllocator &balloc, const StringRef &name) {
   util::inp_strlower(std::ranges::begin(iov), p);
   *p = '\0';
 
-  return StringRef{std::span{std::ranges::begin(iov), p}};
+  return as_string_ref(std::ranges::begin(iov), p);
 }
 } // namespace
 

src/shrpx_http.cc

@@ -41,7 +41,7 @@ StringRef create_error_html(BlockAllocator &balloc, unsigned int http_status) {
   const auto &error_pages = httpconf.error_pages;
   for (const auto &page : error_pages) {
     if (page.http_status == 0 || page.http_status == http_status) {
-      return StringRef{std::span{page.content}};
+      return as_string_ref(page.content);
     }
   }
 
@@ -123,7 +123,7 @@ StringRef create_forwarded(BlockAllocator &balloc, int params,
   --p;
   *p = '\0';
 
-  return StringRef{std::span{std::ranges::begin(iov), p}};
+  return as_string_ref(std::ranges::begin(iov), p);
 }
 
 std::string colorizeHeaders(const char *hdrs) {
@@ -199,7 +199,7 @@ StringRef create_affinity_cookie(BlockAllocator &balloc, const StringRef &name,
     p = std::ranges::copy(SECURE, p).out;
   }
   *p = '\0';
-  return StringRef{std::span{std::ranges::begin(iov), p}};
+  return as_string_ref(std::ranges::begin(iov), p);
 }
 
 bool require_cookie_secure_attribute(SessionAffinityCookieSecure secure,
@@ -262,7 +262,7 @@ StringRef create_altsvc_header_value(BlockAllocator &balloc,
 
   assert(static_cast<size_t>(p - std::ranges::begin(iov)) == len);
 
-  return StringRef{std::span{std::ranges::begin(iov), p}};
+  return as_string_ref(std::ranges::begin(iov), p);
 }
 
 bool check_http_scheme(const StringRef &scheme, bool encrypted) {

src/shrpx_http2_downstream_connection.cc

@@ -444,8 +444,8 @@ int Http2DownstreamConnection::push_request_headers() {
     p = http::create_via_header_value(p, req.http_major, req.http_minor);
     *p = '\0';
 
-    nva.push_back(http2::make_field(
-      "via"_sr, StringRef{std::span{std::ranges::begin(iov), p}}));
+    nva.push_back(
+      http2::make_field("via"_sr, as_string_ref(std::ranges::begin(iov), p)));
   }
 
   auto te = req.fs.header(http2::HD_TE);

src/shrpx_http2_upstream.cc

@@ -1844,8 +1844,8 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
     p = http::create_via_header_value(p, resp.http_major, resp.http_minor);
     *p = '\0';
 
-    nva.push_back(http2::make_field(
-      "via"_sr, StringRef{std::span{std::ranges::begin(iov), p}}));
+    nva.push_back(
+      http2::make_field("via"_sr, as_string_ref(std::ranges::begin(iov), p)));
   }
 
   for (auto &p : httpconf.add_response_headers) {

src/shrpx_http3_upstream.cc

@@ -1383,8 +1383,8 @@ int Http3Upstream::on_downstream_header_complete(Downstream *downstream) {
     p = http::create_via_header_value(p, resp.http_major, resp.http_minor);
     *p = '\0';
 
-    nva.push_back(http3::make_field(
-      "via"_sr, StringRef{std::span{std::ranges::begin(iov), p}}));
+    nva.push_back(
+      http3::make_field("via"_sr, as_string_ref(std::ranges::begin(iov), p)));
   }
 
   for (auto &p : httpconf.add_response_headers) {

src/shrpx_http_downstream_connection.cc

@@ -571,7 +571,7 @@ int HttpDownstreamConnection::push_request_headers() {
       auto iov = make_byte_ref(balloc, base64::encode_length(nonce.size()) + 1);
       auto p = base64::encode(nonce, std::ranges::begin(iov));
       *p = '\0';
-      auto key = StringRef{std::span{std::ranges::begin(iov), p}};
+      auto key = as_string_ref(std::ranges::begin(iov), p);
       downstream_->set_ws_key(key);
 
       buf->append("Sec-Websocket-Key: ");

src/shrpx_https_upstream.cc

@@ -284,7 +284,7 @@ void rewrite_request_host_path_from_uri(BlockAllocator &balloc, Request &req,
     }
     *p = '\0';
 
-    req.authority = StringRef{std::span{std::ranges::begin(iovec), p}};
+    req.authority = as_string_ref(std::ranges::begin(iovec), p);
   } else {
     req.authority = authority;
   }

src/shrpx_log.cc

@@ -548,7 +548,7 @@ StringRef construct_absolute_request_uri(BlockAllocator &balloc,
   p = std::ranges::copy(req.path, p).out;
   *p = '\0';
 
-  return StringRef{std::span{std::ranges::begin(iov), p}};
+  return as_string_ref(std::ranges::begin(iov), p);
 }
 } // namespace
 

src/shrpx_worker.cc

@@ -1286,7 +1286,7 @@ size_t match_downstream_addr_group_host(
     auto ep =
       std::copy(std::begin(host) + 1, std::end(host), std::begin(rev_host_src));
     std::reverse(std::begin(rev_host_src), ep);
-    auto rev_host = StringRef{std::span{std::begin(rev_host_src), ep}};
+    auto rev_host = as_string_ref(std::begin(rev_host_src), ep);
 
     ssize_t best_group = -1;
     const RNode *last_node = nullptr;
@@ -1387,7 +1387,7 @@ size_t match_downstream_addr_group(
     auto ep = std::copy(std::begin(host), std::end(host), std::begin(low_host));
     *ep = '\0';
     util::inp_strlower(std::begin(low_host), ep);
-    host = StringRef{std::span{std::begin(low_host), ep}};
+    host = as_string_ref(std::begin(low_host), ep);
   }
   return match_downstream_addr_group_host(routerconf, host, path, groups,
                                           catch_all, balloc);

src/template.h

@@ -504,6 +504,26 @@ requires(std::ranges::contiguous_range<R> && std::ranges::sized_range<R> &&
     std::ranges::size(r)};
 }
 
+// Returns StringRef over a given range |r|.
+template <typename R>
+requires(std::ranges::contiguous_range<R> && std::ranges::sized_range<R> &&
+         std::ranges::borrowed_range<R> &&
+         sizeof(std::ranges::range_value_t<R>) == sizeof(StringRef::value_type))
+[[nodiscard]] StringRef as_string_ref(R &&r) {
+  return StringRef{
+    reinterpret_cast<StringRef::const_pointer>(std::ranges::data(r)),
+    std::ranges::size(r)};
+}
+
+// Returns StringRef over a given range [|first|, |last|).
+template <std::contiguous_iterator I>
+requires(sizeof(std::iter_value_t<I>) == sizeof(StringRef::value_type))
+[[nodiscard]] StringRef as_string_ref(I first, I last) {
+  return StringRef{
+    reinterpret_cast<StringRef::const_pointer>(std::to_address(first)),
+    static_cast<size_t>(std::ranges::distance(first, last))};
+}
+
 inline int run_app(std::function<int(int, char **)> app, int argc,
                    char **argv) {
   try {

src/template_test.cc

@@ -42,6 +42,7 @@ const MunitTest tests[]{
   munit_void_test(test_template_string_ref),
   munit_void_test(test_template_as_uint8_span),
   munit_void_test(test_template_as_string_view),
+  munit_void_test(test_template_as_string_ref),
   munit_test_end(),
 };
 } // namespace
@@ -251,4 +252,20 @@ void test_template_as_string_view(void) {
   }
 }
 
+void test_template_as_string_ref(void) {
+  {
+    auto a = std::to_array<uint8_t>({'a', 'l', 'p', 'h', 'a'});
+
+    assert_stdsv_equal("alpha"sv, as_string_ref(a));
+    assert_stdsv_equal("alpha"sv, as_string_ref(a.begin(), a.end()));
+  }
+
+  {
+    auto s = ""s;
+
+    assert_stdsv_equal(""sv, as_string_ref(s));
+    assert_stdsv_equal(""sv, as_string_ref(s.begin(), s.end()));
+  }
+}
+
 } // namespace nghttp2

src/template_test.h

@@ -41,6 +41,7 @@ munit_void_test_decl(test_template_immutable_string)
 munit_void_test_decl(test_template_string_ref)
 munit_void_test_decl(test_template_as_uint8_span)
 munit_void_test_decl(test_template_as_string_view)
+munit_void_test_decl(test_template_as_string_ref)
 
 } // namespace nghttp2
 

src/util.cc

@@ -201,7 +201,7 @@ StringRef percent_encode_token(BlockAllocator &balloc,
 
   *p = '\0';
 
-  return StringRef{std::span{std::begin(iov), p}};
+  return as_string_ref(std::begin(iov), p);
 }
 
 size_t percent_encode_tokenlen(const StringRef &target) {
@@ -247,7 +247,7 @@ StringRef quote_string(BlockAllocator &balloc, const StringRef &target) {
 
   *p = '\0';
 
-  return StringRef{std::span{std::begin(iov), p}};
+  return as_string_ref(std::begin(iov), p);
 }
 
 size_t quote_stringlen(const StringRef &target) {
@@ -517,7 +517,7 @@ StringRef format_hex(BlockAllocator &balloc, std::span<const uint8_t> s) {
 
   *p = '\0';
 
-  return StringRef{std::span{std::begin(iov), p}};
+  return as_string_ref(std::begin(iov), p);
 }
 
 void to_token68(std::string &base64str) {
@@ -560,7 +560,7 @@ StringRef to_base64(BlockAllocator &balloc, const StringRef &token68str) {
 
   *p = '\0';
 
-  return StringRef{std::span{std::begin(iov), p}};
+  return as_string_ref(std::begin(iov), p);
 }
 
 namespace {
@@ -1614,7 +1614,7 @@ StringRef percent_decode(BlockAllocator &balloc, const StringRef &src) {
     *p++ = *first;
   }
   *p = '\0';
-  return StringRef{std::span{std::begin(iov), p}};
+  return as_string_ref(std::begin(iov), p);
 }
 
 // Returns x**y

src/util.h

@@ -401,7 +401,7 @@ StringRef make_string_ref_uint(BlockAllocator &balloc, T n) {
   auto p = std::begin(iov);
   p = util::utos(p, n);
   *p = '\0';
-  return StringRef{std::span{std::begin(iov), p}};
+  return as_string_ref(std::begin(iov), p);
 }
 
 template <typename T> std::string utos_unit(T n) {
@@ -739,7 +739,7 @@ StringRef make_hostport(OutputIt first, const StringRef &host, uint16_t port) {
 
   *p = '\0';
 
-  return StringRef{std::span{first, p}};
+  return as_string_ref(first, p);
 }
 
 // Creates "host:port" string using given |host| and |port|.  If
@@ -770,7 +770,7 @@ StringRef make_http_hostport(OutputIt first, const StringRef &host,
 
   *p = '\0';
 
-  return StringRef{std::span{first, p}};
+  return as_string_ref(first, p);
 }
 
 // hexdump dumps |data| of length |datalen| in the format similar to