[AIS] Fix plenty of small bugs unveiled by aishub test campaign.

A test campaign was run with live data from aishub.net (ca. 25 millions
sentence, 1.2 GB of logs), the goal was to check the decoding and the JSON
parsing and dumping code.
On all the AIS data, the following tests were done:
- AIVDM decoding
- JSON scaled dump
- JSON validity check on scaled dump.
- JSON unscaled dump
- JSON validity check on unscaled dump
- JSON unscaled idempotency check
- JSON unscaled/scaled idempotency check

The last check consisted of:
- parsing the unscaled dump
- dumping it back in scaled mode
- compare it with the original scaled dump.

This test campaign has unveiled plenty of small bugs all around the AIS code.
This patch fixes all of them and adds new sentences in the regression tests.

1 files changed, 22 insertions, 2 deletions

diff --git a/driver_ais.c b/driver_ais.c
index 385a448c..af58fcaa 100644
--- a/driver_ais.c
+++ b/driver_ais.c
@@ -204,6 +204,7 @@ bool ais_binary_decode(struct ais_t *ais,
 		ais->type6.dac1fid12.amount		= UBITS(345, 10);
 		ais->type6.dac1fid12.unit		= UBITS(355, 2);
 		/* skip 3 bits */
+		imo = true;
 		break;
 	    case 14:	/* IMO236 - Tidal Window */
 		ais->type6.dac1fid32.month	= UBITS(88, 4);
@@ -225,9 +226,11 @@ bool ais_binary_decode(struct ais_t *ais,
 		ais->type6.dac1fid32.ntidals = u;
 #undef ARRAY_BASE
 #undef ELEMENT_SIZE
+		imo = true;
 		break;
 	    case 15:	/* IMO236 - Extended Ship Static and Voyage Related Data */
 		ais->type6.dac1fid15.airdraught	= UBITS(56, 11);
+		imo = true;
 		break;
 	    case 16:	/* IMO236 - Number of persons on board */
 		if (ais->type6.bitcount == 136)
@@ -247,6 +250,7 @@ bool ais_binary_decode(struct ais_t *ais,
 		ais->type6.dac1fid18.lon	= SBITS(268, 25);
 		ais->type6.dac1fid18.lat	= SBITS(293, 24);
 		/* skip 43 bits */
+		imo = true;
 		break;
 	    case 20:	/* IMO289 - Berthing data - addressed */
 		ais->type6.dac1fid20.linkage	= UBITS(88, 10);
@@ -287,6 +291,7 @@ bool ais_binary_decode(struct ais_t *ais,
 		UCHARS(191, ais->type6.dac1fid20.berth_name);
 		ais->type6.dac1fid20.berth_lon	= SBITS(311, 25);
 		ais->type6.dac1fid20.berth_lat	= SBITS(336, 24);
+		imo = true;
 		break;
 	    case 23:        /* IMO289 - Area notice - addressed */
 		break;
@@ -298,6 +303,7 @@ bool ais_binary_decode(struct ais_t *ais,
 		    ais->type6.dac1fid25.cargos[u].subtype = UBITS(104+u*17,13);
 		}
 		ais->type6.dac1fid25.ncargos = u;
+		imo = true;
 		break;
 	    case 28:	/* IMO289 - Route info - addressed */
 		ais->type6.dac1fid28.linkage	= UBITS(88, 10);
@@ -318,12 +324,14 @@ bool ais_binary_decode(struct ais_t *ais,
 		}
 #undef ARRAY_BASE
 #undef ELEMENT_SIZE
+		imo = true;
 		break;
 	    case 30:	/* IMO289 - Text description - addressed */
 		ais->type6.dac1fid30.linkage   = UBITS(88, 10);
 		from_sixbit((char *)bits,
 			    98, bitlen-98,
 			    ais->type6.dac1fid30.text);
+		imo = true;
 		break;
 	    case 32:	/* IMO289 - Tidal Window */
 		ais->type6.dac1fid32.month	= UBITS(88, 4);
@@ -345,6 +353,7 @@ bool ais_binary_decode(struct ais_t *ais,
 		ais->type6.dac1fid32.ntidals = u;
 #undef ARRAY_BASE
 #undef ELEMENT_SIZE
+		imo = true;
 		break;
 	    }
 	if (!imo)
@@ -443,10 +452,12 @@ bool ais_binary_decode(struct ais_t *ais,
 		ais->type8.dac1fid13.thour  	= UBITS(457, 5);
 		ais->type8.dac1fid13.tminute	= UBITS(462, 6);
 		/* skip 4 bits */
+		imo = true;
 		break;
 	    case 15:        /* IMO236 - Extended ship and voyage */
 		ais->type8.dac1fid15.airdraught	= UBITS(56, 11);
 		/* skip 5 bits */
+		imo = true;
 		break;
 	    case 17:        /* IMO289 - VTS-generated/synthetic targets */
 #define ARRAY_BASE 56
@@ -479,6 +490,7 @@ bool ais_binary_decode(struct ais_t *ais,
 		ais->type8.dac1fid17.ntargets = u;
 #undef ARRAY_BASE
 #undef ELEMENT_SIZE
+		imo = true;
 		break;
 	    case 19:        /* IMO289 - Marine Traffic Signal */
 		ais->type8.dac1fid19.linkage	= UBITS(56, 10);
@@ -491,6 +503,7 @@ bool ais_binary_decode(struct ais_t *ais,
 		ais->type8.dac1fid19.minute	= UBITS(247, 6);
 		ais->type8.dac1fid19.nextsignal	= UBITS(253, 5);
 		/* skip 102 bits */
+		imo = true;
 		break;
 	    case 21:        /* IMO289 - Weather obs. report from ship */
 		break;
@@ -519,12 +532,14 @@ bool ais_binary_decode(struct ais_t *ais,
 		}
 #undef ARRAY_BASE
 #undef ELEMENT_SIZE
+		imo = true;
 		break;
 	    case 29:        /* IMO289 - Text Description - broadcast */
 		ais->type8.dac1fid29.linkage   = UBITS(56, 10);
 		from_sixbit((char *)bits,
 			    66, bitlen-66,
 			    ais->type8.dac1fid29.text);
+		imo = true;
 		break;
 	    case 31:        /* IMO289 - Meteorological/Hydrological data */
 		ais->type8.dac1fid31.lon		= SBITS(56, 25);
@@ -807,8 +822,8 @@ bool ais_binary_decode(struct ais_t *ais,
 	    ais->type22.area.sw_lon       = SBITS(104, 18);
 	    ais->type22.area.sw_lat       = SBITS(122, 17);
 	} else {
-	    ais->type22.mmsi.dest1             = SBITS(69, 30);
-	    ais->type22.mmsi.dest2             = SBITS(104, 30);
+	    ais->type22.mmsi.dest1             = UBITS(69, 30);
+	    ais->type22.mmsi.dest2             = UBITS(104, 30);
 	}
 	ais->type22.band_a       = UBITS(140, 1);
 	ais->type22.band_b       = UBITS(141, 1);
@@ -946,6 +961,11 @@ bool ais_binary_decode(struct ais_t *ais,
 		     (ais->type26.bitcount + 7) / 8);
 	break;
     case 27:	/* Long Range AIS Broadcast message */
+	if (bitlen != 96) {
+	    gpsd_report(LOG_WARN, "AIVDM message type 27 size not 96 bits (%zd).\n",
+			bitlen);
+	    return false;
+	}
 	ais->type27.accuracy        = (bool)UBITS(38, 1);
 	ais->type27.raim		= UBITS(39, 1)!=0;
 	ais->type27.status		= UBITS(40, 4);