[core] adjust r->http_host ptr caching

faster to use http_header_request_set_ptr() and buffer_copy_string_len()
than to use http_header_request_set() and http_header_request_get()

check r->http_host for NULL instead of relying on buffer_copy_* to do so

src/mod_extforward.c

@@ -932,11 +932,16 @@ static handler_t mod_extforward_Forwarded (request_st * const r, plugin_data * c
             j += 4; /*(k, klen, v, vlen come in sets of 4)*/
         }
         if (-1 != ohost) {
-            if (extforward_check_proxy
-                && !buffer_string_is_empty(r->http_host)) {
-                http_header_env_set(r,
-                                    CONST_STR_LEN("_L_EXTFORWARD_ACTUAL_HOST"),
-                                    CONST_BUF_LEN(r->http_host));
+            if (!buffer_string_is_empty(r->http_host)) {
+                if (extforward_check_proxy)
+                    http_header_env_set(r,
+                      CONST_STR_LEN("_L_EXTFORWARD_ACTUAL_HOST"),
+                      CONST_BUF_LEN(r->http_host));
+            }
+            else {
+                r->http_host =
+                  http_header_request_set_ptr(r, HTTP_HEADER_HOST,
+                                              CONST_STR_LEN("Host"));
             }
             /* remove trailing spaces/tabs, and double-quotes from host */
             v = offsets[ohost+2];

src/request.c

@@ -460,8 +460,9 @@ static const char * http_request_parse_reqline_uri(request_st * const restrict r
             return NULL;
         }
         /* Insert as host header */
-        http_header_request_set(r, HTTP_HEADER_HOST, CONST_STR_LEN("Host"), host, hostlen);
-        r->http_host = http_header_request_get(r, HTTP_HEADER_HOST, CONST_STR_LEN("Host"));
+        r->http_host = http_header_request_set_ptr(r, HTTP_HEADER_HOST,
+                                                   CONST_STR_LEN("Host"));
+        buffer_copy_string_len(r->http_host, host, hostlen);
         return nuri;
     } else if (!(http_parseopts & HTTP_PARSEOPT_HEADER_STRICT) /*(!http_header_strict)*/
            || (HTTP_METHOD_CONNECT == r->http_method && (uri[0] == ':' || light_isdigit(uri[0])))
@@ -643,11 +644,10 @@ http_request_parse_header (request_st * const restrict r, http_header_parse_ctx
                         return http_request_header_line_invalid(r, 400,
                           "invalid pseudo-header authority too long -> 400");
                     /* insert as host header */
-                    http_header_request_set(r, HTTP_HEADER_HOST,
-                                            CONST_STR_LEN("host"), v, vlen);
                     r->http_host =
-                      http_header_request_get(r, HTTP_HEADER_HOST,
-                                              CONST_STR_LEN("Host"));
+                      http_header_request_set_ptr(r, HTTP_HEADER_HOST,
+                                                  CONST_STR_LEN("Host"));
+                    buffer_copy_string_len(r->http_host, v, vlen);
                     return 0;
                 }
                 break;
@@ -1100,20 +1100,20 @@ http_request_parse (request_st * const restrict r, const int scheme_port)
     int status = http_request_parse_target(r, scheme_port);
     if (0 != status) return status;
 
-    /*(r->http_host might not be set until after parsing request headers)*/
-    buffer_copy_buffer(&r->uri.authority, r->http_host);/*(copy even if empty)*/
-    buffer_to_lower(&r->uri.authority);
-
     /* post-processing */
     const unsigned int http_parseopts = r->conf.http_parseopts;
 
     /* check hostname field if it is set */
-    if (r->http_host) {
+    /*(r->http_host might not be set until after parsing request headers)*/
+    if (__builtin_expect( (r->http_host != NULL), 1)) {
+        buffer_copy_buffer(&r->uri.authority, r->http_host);
+        buffer_to_lower(&r->uri.authority);
         if (0 != http_request_host_policy(r->http_host,
                                           http_parseopts, scheme_port))
             return http_request_header_line_invalid(r, 400, "Invalid Hostname -> 400");
     }
     else {
+        buffer_copy_string_len(&r->uri.authority, CONST_STR_LEN(""));
         if (r->http_version >= HTTP_VERSION_1_1)
             return http_request_header_line_invalid(r, 400, "HTTP/1.1 but Host missing -> 400");
     }

src/response.c

@@ -630,8 +630,12 @@ static handler_t http_response_comeback (request_st * const r)
 
     config_reset_config(r);
 
-    buffer_copy_buffer(&r->uri.authority,r->http_host);/*copy even if NULL*/
-    buffer_to_lower(&r->uri.authority);
+    if (__builtin_expect( (r->http_host != NULL), 1)) {
+        buffer_copy_buffer(&r->uri.authority, r->http_host);
+        buffer_to_lower(&r->uri.authority);
+    }
+    else
+        buffer_copy_string_len(&r->uri.authority, CONST_STR_LEN(""));
 
     int status = http_request_parse_target(r, r->con->proto_default_port);
     if (0 == status) {