Sanity check for the NMEA sentence we try to parse.

- define the used NMEA prefixes.
- Don't blindly skip the common prefix, check the whole NMEA prefix.
- Check that the sentence is long enough to make sense.

diff --git a/src/gps-nmea-parse.c b/src/gps-nmea-parse.c
index 810791a8a52b898413ef6b15e2a03f302cdc83e4..05a7597e468f98c4d40a41a4c935be24098f6a9d 100644 (file)
--- a/src/gps-nmea-parse.c
+++ b/src/gps-nmea-parse.c
@@ -42,6 +42,12 @@
 
 #define DELIM ","
 
+#define NMEA_RMC "$GPRMC"
+#define NMEA_GGA "$GPGGA"
+#define NMEA_GSA "$GPGSA"
+#define NMEA_GSV "$GPGSV"
+#define NMEA_PRLEN (6)
+
 static void
 gps_nmea_parse_rmc(Gps *gps, gchar *sentence)
 {
@@ -367,18 +373,23 @@ gboolean
 gps_nmea_parse(Gps *gps)
 {
 g_assert(gps);
-g_assert(gps->io.nmea);
-
-g_debug("%s(): %s", __PRETTY_FUNCTION__, gps->io.nmea);
-
-if (!strncmp(gps->io.nmea + 3, "GSV", 3)) {
-       gps_nmea_parse_gsv(gps, gps->io.nmea + 7);
-} else if (!strncmp(gps->io.nmea + 3, "RMC", 3))
-       gps_nmea_parse_rmc(gps, gps->io.nmea + 7);
-else if (!strncmp(gps->io.nmea + 3, "GGA", 3))
-       gps_nmea_parse_gga(gps, gps->io.nmea + 7);
-else if (!strncmp(gps->io.nmea + 3, "GSA", 3))
-       gps_nmea_parse_gsa(gps, gps->io.nmea + 7);
+
+g_debug("NMEA: %s", gps->io.nmea);
+
+if (!gps->io.nmea)
+       return FALSE;
+
+if (strlen(gps->io.nmea)<NMEA_PRLEN+1)
+       return FALSE;
+
+if (!strncmp(gps->io.nmea, NMEA_GSV, NMEA_PRLEN)) {
+       gps_nmea_parse_gsv(gps, gps->io.nmea + NMEA_PRLEN+1);
+} else if (!strncmp(gps->io.nmea, NMEA_RMC, NMEA_PRLEN))
+       gps_nmea_parse_rmc(gps, gps->io.nmea + NMEA_PRLEN+1);
+else if (!strncmp(gps->io.nmea, NMEA_GGA, NMEA_PRLEN))
+       gps_nmea_parse_gga(gps, gps->io.nmea + NMEA_PRLEN+1);
+else if (!strncmp(gps->io.nmea, NMEA_GSA, NMEA_PRLEN))
+       gps_nmea_parse_gsa(gps, gps->io.nmea + NMEA_PRLEN+1);
 else g_printerr("Unknown NMEA: [%s]\n", gps->io.nmea);
 g_free(gps->io.nmea);
 gps->io.nmea=NULL;