Quickfix: bypass faulty DNS by using default values for localhost.

src/arch/posix/mbed_tcp.cpp

@@ -86,16 +86,35 @@ int mbed_getnameinfo(struct sockaddr* fd, size_t sa_sz, char* name, size_t host_
 
 int mbed_addrinfo(const char* hostname, const char* portstr, struct addrinfo* hints, struct addrinfo** info)
 {
+  static struct sockaddr ai_addr;
+  static struct addrinfo res;
+  bool is_localhost = false;
+
   if (hostname == NULL)
   {
     static const char * localhost = "localhost";
     hostname = localhost;
+    is_localhost = true;
   }
 
   SocketAddress mbed_hints(hostname, atoi(portstr));
   mbed_hints.set_ip_address(Ethernet.localIP().toString().c_str());
   SocketAddress * mbed_res;
 
+  /* Bypass faulty DNS lookup on localhost. */
+  if (is_localhost)
+  {
+    ai_addr.ai = mbed_hints;
+
+    memcpy(&res, hints, sizeof(struct addrinfo));
+
+    res.ai_addr = &ai_addr;
+    res.ai_next = NULL;
+    info[0] = &res;
+
+    return UA_STATUSCODE_GOOD;
+  }
+
   /* rc either holds the number of results uncovered or a negative error code. */
   auto rc = NetworkInterface::get_default_instance()->getaddrinfo(hostname, &mbed_hints, &mbed_res);
   if (rc < 0)
@@ -112,10 +131,8 @@ int mbed_addrinfo(const char* hostname, const char* portstr, struct addrinfo* hi
   }
 
   /* Note: we currently support only a single address result. */
-  static struct sockaddr ai_addr;
   ai_addr.ai = mbed_res[0];
 
-  static struct addrinfo res;
   memcpy(&res, hints, sizeof(struct addrinfo));
 
   res.ai_addr = &ai_addr;