From c6be13e8ef80e5afc836e04cbfe4cb17631540e4 Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Mon, 2 Oct 2017 16:58:53 -0700 Subject: [PATCH] altoslib: Allow early bail-out on bad telemetry CRC Check the CRC status in the packet before creating a new telemetry object. Signed-off-by: Keith Packard --- altoslib/AltosTelemetry.java | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/altoslib/AltosTelemetry.java b/altoslib/AltosTelemetry.java index fe536c6a..a374519d 100644 --- a/altoslib/AltosTelemetry.java +++ b/altoslib/AltosTelemetry.java @@ -28,8 +28,11 @@ public abstract class AltosTelemetry implements AltosDataProvider { int[] bytes; /* All telemetry packets have these fields */ - public int rssi() { return AltosConvert.telem_to_rssi(AltosLib.int8(bytes, bytes.length - 3)); } - public int status() { return AltosLib.uint8(bytes, bytes.length - 2); } + static public int rssi(int[] bytes) { return AltosConvert.telem_to_rssi(AltosLib.int8(bytes, bytes.length - 3)); } + static public int status(int[] bytes) { return AltosLib.uint8(bytes, bytes.length - 2); } + + public int rssi() { return rssi(bytes); } + public int status() { return status(bytes); } /* All telemetry packets report these fields in some form */ public abstract int serial(); @@ -96,6 +99,9 @@ public abstract class AltosTelemetry implements AltosDataProvider { if (!cksum(bytes)) throw new ParseException(String.format("invalid line \"%s\"", hex), 0); + if ((status(bytes) & PKT_APPEND_STATUS_1_CRC_OK) == 0) + throw new AltosCRCException(rssi(bytes)); + /* length, data ..., rssi, status, checksum -- 4 bytes extra */ switch (bytes.length) { case AltosLib.ao_telemetry_standard_len + 4: -- 2.30.2