Make packet sniffer pass packets with bad checksums with type BAD_PACKET.

Such packets used to be truncated to zero length with the packet type
matched before the checksum was bad.  This caused confusion at various
points in the code that were checking for zero-length packets.

All regression tests pass, both in pty and UDP modes.

3 files changed, 17 insertions, 7 deletions

diff --git a/driver_nmea.c b/driver_nmea.c
index 870b4858..1a5b3683 100644
--- a/driver_nmea.c
+++ b/driver_nmea.c
@@ -469,14 +469,14 @@ static gps_mask_t processGPGSV(int count, char *field[],
     if (count <= 3) {
 	gpsd_zero_satellites(&session->gpsdata);
 	session->gpsdata.satellites_visible = 0;
-	return ERROR_IS;
+	return 0;
     }
     if (count % 4 != 0) {
 	gpsd_report(LOG_WARN, "malformed GPGSV - fieldcount %d %% 4 != 0\n",
 		    count);
 	gpsd_zero_satellites(&session->gpsdata);
 	session->gpsdata.satellites_visible = 0;
-	return ERROR_IS;
+	return 0;
     }
 
     session->driver.nmea.await = atoi(field[1]);
@@ -519,7 +519,7 @@ static gps_mask_t processGPGSV(int count, char *field[],
     if (session->driver.nmea.part < session->driver.nmea.await) {
 	gpsd_report(LOG_PROG, "Partial satellite data (%d of %d).\n",
 		    session->driver.nmea.part, session->driver.nmea.await);
-	return ERROR_IS;
+	return 0;
     }
     /*
      * This sanity check catches an odd behavior of SiRFstarII receivers.
@@ -535,7 +535,7 @@ static gps_mask_t processGPGSV(int count, char *field[],
     gpsd_report(LOG_WARN, "Satellite data no good (%d of %d).\n",
 		session->driver.nmea.part, session->driver.nmea.await);
     gpsd_zero_satellites(&session->gpsdata);
-    return ERROR_IS;
+    return 0;
   sane:
     session->gpsdata.skyview_time = NAN;
     gpsd_report(LOG_DATA, "GSV: Satellite data OK (%d of %d).\n",
diff --git a/gps/fake.py b/gps/fake.py
index 65cc560b..d5ea5f5c 100644
--- a/gps/fake.py
+++ b/gps/fake.py
@@ -103,8 +103,6 @@ class TestLoad:
             (len, ptype, packet) = getter.get(logfp.fileno())
             if len <= 0:
                 break
-            elif ptype == sniffer.BAD_PACKET:
-                break
             elif ptype == sniffer.COMMENT_PACKET:
                 # Some comments are magic
                 if "Serial:" in packet:
diff --git a/packet.c b/packet.c
index 26b6d6b8..8b107d1c 100644
--- a/packet.c
+++ b/packet.c
@@ -1152,6 +1152,7 @@ void packet_parse(struct gps_packet_t *lexer)
 		gpsd_report(LOG_WARN,
 			    "bad checksum in NMEA packet; expected %s.\n",
 			    csum);
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 	    }
 	    packet_discard(lexer);
@@ -1169,8 +1170,10 @@ void packet_parse(struct gps_packet_t *lexer)
 	    crc &= 0x7fff;
 	    if (checksum == crc)
 		packet_accept(lexer, SIRF_PACKET);
-	    else
+	    else {
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
+	    }
 	    packet_discard(lexer);
 	    break;
 	}
@@ -1191,6 +1194,7 @@ void packet_parse(struct gps_packet_t *lexer)
 		gpsd_report(LOG_IO, "REJECT SuperStarII packet type 0x%02x"
 			    "%zd bad checksum 0x%04x, expecting 0x%04x\n",
 			    lexer->inbuffer[1], lexer->length, a, b);
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 	    } else {
 		packet_accept(lexer, SUPERSTAR2_PACKET);
@@ -1216,6 +1220,7 @@ void packet_parse(struct gps_packet_t *lexer)
 	    } else {
 		gpsd_report(LOG_IO, "REJECT OnCore packet @@%c%c len %d\n",
 			    lexer->inbuffer[2], lexer->inbuffer[3], len);
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 	    }
 	    packet_discard(lexer);
@@ -1415,6 +1420,7 @@ void packet_parse(struct gps_packet_t *lexer)
 		 * More attempts to recognize ambiguous TSIP-like
 		 * packet types could go here.
 		 */
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 		packet_discard(lexer);
 		break;
@@ -1435,6 +1441,7 @@ void packet_parse(struct gps_packet_t *lexer)
 					lexer->inbufptr - lexer->inbuffer -
 					3), lexer->inbufptr[-3],
 			    lexer->inbufptr[-2], lexer->inbufptr[-1]);
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 		packet_discard(lexer);
 	    }
@@ -1454,6 +1461,7 @@ void packet_parse(struct gps_packet_t *lexer)
 		gpsd_report(LOG_IO,
 			    "Zodiac data checksum 0x%hx over length %hd, expecting 0x%hx\n",
 			    sum, len, getword(5 + len));
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 	    }
 	    packet_discard(lexer);
@@ -1485,6 +1493,7 @@ void packet_parse(struct gps_packet_t *lexer)
 			    lexer->inbuffer[len - 2],
 			    lexer->inbuffer[len - 1],
 			    lexer->inbuffer[2], lexer->inbuffer[3]);
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 	    }
 	    packet_discard(lexer);
@@ -1535,6 +1544,7 @@ void packet_parse(struct gps_packet_t *lexer)
 	    packet_discard(lexer);
 	    break;
 	  not_evermore:
+	    packet_accept(lexer, BAD_PACKET);
 	    lexer->state = GROUND_STATE;
 	    packet_discard(lexer);
 	    break;
@@ -1571,6 +1581,7 @@ void packet_parse(struct gps_packet_t *lexer)
 			    "ITALK: checksum failed - "
 			    "type 0x%02x expected 0x%04x got 0x%04x\n",
 			    lexer->inbuffer[4], xsum, csum);
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 	    }
 	    packet_discard(lexer);
@@ -1608,6 +1619,7 @@ void packet_parse(struct gps_packet_t *lexer)
 		lexer->state = GROUND_STATE;
 		break;
 	    } else {
+		packet_accept(lexer, BAD_PACKET);
 		lexer->state = GROUND_STATE;
 	    }
 	}