Fixing libunit 'off by 2' issue in library.

Name and value in each header are 0-terminated, so additional 2 bytes
should be allocated for them.  There were several attempts to add these
2 bytes to headers in language modules, but some modules weren't updated.
Also, adding these 2 bytes is specific to the implementation which may be
changed later, so extending this mechanics to modules may cause errors.

src/go/unit/response.go

@@ -63,7 +63,7 @@ func (r *response) WriteHeader(code int) {
 	for k, vv := range r.header {
 		for _, v := range vv {
 			fields++
-			fields_size += len(k) + len(v) + 2
+			fields_size += len(k) + len(v)
 		}
 	}
 

src/nodejs/unit-http/unit.cpp

@@ -629,9 +629,6 @@ Unit::response_send_headers(napi_env env, napi_callback_info info)
         keys_count = napi.get_value_uint32(argv[2]);
         header_len = napi.get_value_uint32(argv[3]);
 
-        /* Need to reserve extra byte for C-string 0-termination. */
-        header_len++;
-
         headers = argv[1];
 
         ret = nxt_unit_response_init(req, status_code, keys_count, header_len);
@@ -640,6 +637,12 @@ Unit::response_send_headers(napi_env env, napi_callback_info info)
             return nullptr;
         }
 
+        /*
+         * Each name and value are 0-terminated by libunit.
+         * Need to add extra 2 bytes for each header.
+         */
+        header_len += keys_count * 2;
+
         keys = napi.get_property_names(headers);
         keys_len = napi.get_array_length(keys);
 
@@ -656,8 +659,8 @@ Unit::response_send_headers(napi_env env, napi_callback_info info)
             name_len = napi.get_value_string_latin1(name, ptr, header_len);
             name_ptr = ptr;
 
-            ptr += name_len;
+            ptr += name_len + 1;
-            header_len -= name_len;
+            header_len -= name_len + 1;
 
             hash = nxt_unit_field_hash(name_ptr, name_len);
 
@@ -689,8 +692,8 @@ Unit::response_send_headers(napi_env env, napi_callback_info info)
                     nxt_unit_sptr_set(&f->value, ptr);
                     f->value_length = (uint32_t) value_len;
 
-                    ptr += value_len;
+                    ptr += value_len + 1;
-                    header_len -= value_len;
+                    header_len -= value_len + 1;
 
                     req->response->fields_count++;
                 }
@@ -715,8 +718,8 @@ Unit::response_send_headers(napi_env env, napi_callback_info info)
                 nxt_unit_sptr_set(&f->value, ptr);
                 f->value_length = (uint32_t) value_len;
 
-                ptr += value_len;
+                ptr += value_len + 1;
-                header_len -= value_len;
+                header_len -= value_len + 1;
 
                 req->response->fields_count++;
             }

src/nxt_unit.c

@@ -1316,8 +1316,12 @@ nxt_unit_response_init(nxt_unit_request_info_t *req,
         nxt_unit_req_debug(req, "duplicate response init");
     }
 
+    /*
+     * Each field name and value 0-terminated by libunit,
+     * this is the reason of '+ 2' below.
+     */
     buf_size = sizeof(nxt_unit_response_t)
-               + max_fields_count * sizeof(nxt_unit_field_t)
+               + max_fields_count * (sizeof(nxt_unit_field_t) + 2)
                + max_fields_size;
 
     if (nxt_slow_path(req->response_buf != NULL)) {
@@ -1391,8 +1395,12 @@ nxt_unit_response_realloc(nxt_unit_request_info_t *req,
         return NXT_UNIT_ERROR;
     }
 
+    /*
+     * Each field name and value 0-terminated by libunit,
+     * this is the reason of '+ 2' below.
+     */
     buf_size = sizeof(nxt_unit_response_t)
-               + max_fields_count * sizeof(nxt_unit_field_t)
+               + max_fields_count * (sizeof(nxt_unit_field_t) + 2)
                + max_fields_size;
 
     nxt_unit_req_debug(req, "realloc %"PRIu32"", buf_size);

src/test/nxt_unit_websocket_chat.c

@@ -104,10 +104,10 @@ ws_chat_root(nxt_unit_request_info_t *req)
 
     rc = nxt_unit_response_init(req, 200 /* Status code. */,
                                 2 /* Number of response headers. */,
-                                nxt_length(CONTENT_TYPE) + 1
+                                nxt_length(CONTENT_TYPE)
-                                + nxt_length(TEXT_HTML) + 1
+                                + nxt_length(TEXT_HTML)
-                                + nxt_length(CONTENT_LENGTH) + 1
+                                + nxt_length(CONTENT_LENGTH)
-                                + ws_chat_index_content_length_size + 1
+                                + ws_chat_index_content_length_size
                                 + ws_chat_index_html_size);
     if (nxt_slow_path(rc != NXT_UNIT_OK)) {
         return rc;