build ip utils

Change-Id: Ie4a7482794298204b6137ea8367cb183fdbc23d2
diff --git a/src/ip_utils.cpp b/src/ip_utils.cpp
index e3fd748..8bda174 100644
--- a/src/ip_utils.cpp
+++ b/src/ip_utils.cpp
@@ -15,9 +15,10 @@
  *  along with this program. If not, see <https://www.gnu.org/licenses/>.
  */
 #include "ip_utils.h"
-#include "logger.h"
+#include "sip_utils.h"
+#include "string_utils.h"
 
-#include "connectivity/sip_utils.h"
+#include <fmt/format.h>
 
 #include <sys/types.h>
 #include <unistd.h>
@@ -52,7 +53,7 @@
 sip_strerror(pj_status_t code)
 {
     thread_local char err_msg[PJ_ERR_MSG_SIZE];
-    return as_view(pj_strerror(code, err_msg, sizeof err_msg));
+    return sip_utils::as_view(pj_strerror(code, err_msg, sizeof err_msg));
 }
 
 
@@ -185,7 +186,7 @@
     std::vector<std::string_view> tokens = split_string(localHostStr, '.');
     // Build a gateway address from the individual ip components.
     for (unsigned i = 0; i <= (unsigned) prefix; i++)
-        defaultGw += tokens[i] + ".";
+        defaultGw = fmt::format("{:s}{:s}.", defaultGw, tokens[i]);
     for (unsigned i = (unsigned) ip_utils::subnet_mask::prefix_32bit;
          i > (unsigned) prefix + 1;
          i--)