Changed T.38 terminal handling, so errors from the user's packet transmit…

Changed T.38 terminal handling, so errors from the user's packet transmit routine properly filter up the chain, cause termination of the FAX session, and are reported to the caller.

libs/spandsp/src/t38_core.c

@@ -799,7 +799,11 @@ SPAN_DECLARE(int) t38_core_send_indicator(t38_core_state_t *s, int indicator)
                 return len;
             }
             span_log(&s->logging, SPAN_LOG_FLOW, "Tx %5d: indicator %s\n", s->tx_seq_no, t38_indicator_to_str(indicator));
-            s->tx_packet_handler(s, s->tx_packet_user_data, buf, len, transmissions);
+            if (s->tx_packet_handler(s, s->tx_packet_user_data, buf, len, transmissions) < 0)
+            {
+                span_log(&s->logging, SPAN_LOG_PROTOCOL_WARNING, "Tx Packet Handler Failure\n");
+                return -1;
+            }
             s->tx_seq_no = (s->tx_seq_no + 1) & 0xFFFF;
             delay = modem_startup_time[indicator].training;
             if (s->allow_for_tep)
@@ -837,7 +841,11 @@ SPAN_DECLARE(int) t38_core_send_data(t38_core_state_t *s, int data_type, int fie
         span_log(&s->logging, SPAN_LOG_FLOW, "T.38 data len is %d\n", len);
         return len;
     }
-    s->tx_packet_handler(s, s->tx_packet_user_data, buf, len, s->category_control[category]);
+    if (s->tx_packet_handler(s, s->tx_packet_user_data, buf, len, s->category_control[category]) < 0)
+    {
+        span_log(&s->logging, SPAN_LOG_PROTOCOL_WARNING, "Tx Packet Handler Failure\n");
+        return -1;
+    }
     s->tx_seq_no = (s->tx_seq_no + 1) & 0xFFFF;
     return 0;
 }
@@ -853,7 +861,11 @@ SPAN_DECLARE(int) t38_core_send_data_multi_field(t38_core_state_t *s, int data_t
         span_log(&s->logging, SPAN_LOG_FLOW, "T.38 data len is %d\n", len);
         return len;
     }
-    s->tx_packet_handler(s, s->tx_packet_user_data, buf, len, s->category_control[category]);
+    if (s->tx_packet_handler(s, s->tx_packet_user_data, buf, len, s->category_control[category]) < 0)
+    {
+        span_log(&s->logging, SPAN_LOG_PROTOCOL_WARNING, "Tx Packet Handler Failure\n");
+        return -1;
+    }
     s->tx_seq_no = (s->tx_seq_no + 1) & 0xFFFF;
     return 0;
 }