DHCP time elapsed time write fix.

Author: Juha Heiskanen

source/libDHCPv6/dhcp_service_api.c

@@ -794,7 +794,7 @@ uint32_t dhcp_service_send_req(uint16_t instance_id, uint8_t options, void *ptr,
     msg_tr_ptr->socket = dhcp_service->dhcp_client_socket;
     msg_tr_ptr->recv_resp_cb = receive_resp_cb;
     msg_tr_ptr->delayed_tx = delay_tx;
-    msg_tr_ptr->first_transmit_time = protocol_core_monotonic_time;
+    msg_tr_ptr->first_transmit_time = 0;
     dhcp_tr_set_retry_timers(msg_tr_ptr, msg_tr_ptr->msg_ptr[0]);
     common_write_24_bit(msg_tr_ptr->msg_tr_id, &msg_tr_ptr->msg_ptr[1]);
 
@@ -852,8 +852,9 @@ void dhcp_service_send_message(msg_tr_t *msg_tr_ptr)
     const uint32_t address_pref = SOCKET_IPV6_PREFER_SRC_6LOWPAN_SHORT;
     dhcp_options_msg_t elapsed_time;
 
-    if (libdhcpv6_message_option_discover((msg_tr_ptr->msg_ptr + 4), (msg_tr_ptr->msg_len - 4), DHCPV6_ELAPSED_TIME_OPTION, &elapsed_time) == 0 &&
+    if (msg_tr_ptr->first_transmit_time && libdhcpv6_message_option_discover((msg_tr_ptr->msg_ptr + 4), (msg_tr_ptr->msg_len - 4), DHCPV6_ELAPSED_TIME_OPTION, &elapsed_time) == 0 &&
             elapsed_time.len == 2) {
+
         uint32_t t = protocol_core_monotonic_time - msg_tr_ptr->first_transmit_time; // time in 1/10s ticks
         uint16_t cs;
         if (t > 0xffff / 10) {
@@ -926,6 +927,10 @@ void dhcp_service_send_message(msg_tr_t *msg_tr_ptr)
             int16_t tc = 0;
             socket_setsockopt(msg_tr_ptr->socket, SOCKET_IPPROTO_IPV6, SOCKET_IPV6_TCLASS, &tc, sizeof(tc));
             retval = socket_sendto(msg_tr_ptr->socket, &msg_tr_ptr->addr, msg_tr_ptr->msg_ptr, msg_tr_ptr->msg_len);
+            if (msg_tr_ptr->first_transmit_time == 0 && retval == 0) {
+                //Mark first pushed message timestamp
+                msg_tr_ptr->first_transmit_time = protocol_core_monotonic_time ? protocol_core_monotonic_time : 1;
+            }
         }
     }
     if (retval != 0) {