Better calculate the transmit timeout for packets

Some packets(such as firmware upgrade packets) can be so large that they will
cause a timeout on libosdp, especially at slower baud rates.  Add in a way to
calculate how long the packet transmission should take in order to have an
acceptable timeout.

See: #282

Author: Robert Middleton

src/osdp_common.h

@@ -417,6 +417,7 @@ struct osdp_pd {
 	tick_t tstamp;         /* Last POLL command issued time in ticks */
 	tick_t sc_tstamp;      /* Last received secure reply time in ticks */
 	tick_t phy_tstamp;     /* Time in ticks since command was sent */
+	tick_t resp_expected;  /* Time in ticks when the response is expected */
 	uint32_t request;      /* Event loop requests */
 
 	uint16_t peer_rx_size; /* Receive buffer size of the peer PD/CP */

src/osdp_cp.c

@@ -795,6 +795,10 @@ static void cp_phy_state_wait(struct osdp_pd *pd, uint32_t wait_ms)
 	pd->phy_state = OSDP_CP_PHY_STATE_WAIT;
 }
 
+static int cp_calculate_transmit_time(struct osdp_pd* pd){
+	return (pd->packet_buf_len * 10000U + pd->baud_rate - 1) / pd->baud_rate;
+}
+
 static int cp_phy_state_update(struct osdp_pd *pd)
 {
 	int rc, ret = OSDP_CP_ERR_DEFER;
@@ -825,6 +829,7 @@ static int cp_phy_state_update(struct osdp_pd *pd)
 		pd->reply_id = REPLY_INVALID;
 		pd->phy_state = OSDP_CP_PHY_STATE_REPLY_WAIT;
 		pd->phy_tstamp = osdp_millis_now();
+		pd->resp_expected = pd->phy_tstamp + OSDP_RESP_TOUT_MS + cp_calculate_transmit_time(pd);
 		break;
 	case OSDP_CP_PHY_STATE_REPLY_WAIT:
 		rc = cp_process_reply(pd);
@@ -851,7 +856,7 @@ static int cp_phy_state_update(struct osdp_pd *pd)
 			cp_phy_state_wait(pd, OSDP_CMD_RETRY_WAIT_MS);
 			return OSDP_CP_ERR_DEFER;
 		}
-		if (osdp_millis_since(pd->phy_tstamp) > OSDP_RESP_TOUT_MS) {
+		if (osdp_millis_since(pd->phy_tstamp) > pd->resp_expected) {
 			if (pd->phy_retry_count < OSDP_CMD_MAX_RETRIES) {
 				pd->phy_retry_count += 1;
 				LOG_WRN("No response in 200ms; probing (%d)",