From 6fcb7ccd37b4eaadc2219bfe7dab91c2907da844 Mon Sep 17 00:00:00 2001
From: Michael Black W9MDB <mdblack98@yahoo.com>
Date: Thu, 11 Mar 2021 10:24:22 -0600
Subject: [PATCH] Fixed icom ACK/NAK and frame responses
 https://github.com/Hamlib/Hamlib/issues/600

---
 rigs/icom/frame.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/rigs/icom/frame.c b/rigs/icom/frame.c
index 9968e2a33..2d1664a94 100644
--- a/rigs/icom/frame.c
+++ b/rigs/icom/frame.c
@@ -269,6 +269,9 @@ int icom_one_transaction(RIG *rig, int cmd, int subcmd,
         /* Ok, normal frame */
         break;
 
+    case NAK:
+        RETURNFUNC(-RIG_ERJCTED);
+
     default:
         /* Timeout after reading at least one character */
         /* Problem on ci-v bus? */
@@ -277,13 +280,14 @@ int icom_one_transaction(RIG *rig, int cmd, int subcmd,
 
     if (frm_len < ACKFRMLEN) { RETURNFUNC(-RIG_EPROTO); }
 
+    rig_debug(RIG_DEBUG_TRACE, "%s: frm_len=%d, frm_len-1=%02x, frm_len-2=%02x\n", __func__, frm_len, buf[frm_len-1], buf[frm_len-2]);
     if (NAK == buf[frm_len - 2]) { RETURNFUNC(-RIG_ERJCTED); }
 
-    if (ACK != buf[frm_len - 2]) { RETURNFUNC(-RIG_BUSBUSY); }
+    // has to be one of these two now or frame is corrupt
+    if (FI != buf[frm_len - 1] && ACK != buf[frm_len - 1]) { RETURNFUNC(-RIG_BUSBUSY); }
 
     *data_len = frm_len - (ACKFRMLEN - 1);
-    rig_debug(RIG_DEBUG_TRACE, "%s: data_len=%d, frm_len=%d\n", __func__, *data_len,
-              frm_len);
+    if (*data_len <= 0) { RETURNFUNC(-RIG_EPROTO); }
     memcpy(data, buf + 4, *data_len);
 
     /*