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DSM decoder: Guard against invalid values

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This commit is contained in:
Lorenz Meier 2015-12-14 16:10:14 +00:00
parent 5b4b5de34c
commit d84fcfffaf
1 changed files with 13 additions and 9 deletions
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22
src/lib/rc/dsm.c
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@ -439,15 +439,6 @@ dsm_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values, bool
/* scaled integer for decent accuracy while staying efficient */
value = ((((int)value - 1024) * 1000) / 1700) + 1500;
/* if the value is unrealistic, fail the parsing entirely */
if (value < 600 || value > 2400) {
#ifdef DSM_DEBUG
printf("DSM: VALUE RANGE FAIL\n");
#endif
dsm_chan_count = 0;
return false;
}
/*
* Store the decoded channel into the R/C input buffer, taking into
* account the different ideas about channel assignement that we have.
@ -498,6 +489,18 @@ dsm_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values, bool
printf("PARSED PACKET\n");
#endif
/* check all values */
for (unsigned i = 0; i < *num_values; i++) {
/* if the value is unrealistic, fail the parsing entirely */
if (values[i] < 600 || values[i] > 2400) {
#ifdef DSM_DEBUG
printf("DSM: VALUE RANGE FAIL\n");
#endif
dsm_chan_count = 0;
return false;
}
}
return true;
}
@ -641,6 +644,7 @@ dsm_parse(uint64_t now, uint8_t *frame, unsigned len, uint16_t *values,
/* if decoding failed, set proto to desync */
if (decode_ret == false) {
dsm_decode_state = DSM_DECODE_STATE_DESYNC;
dsm_frame_drops++;
}
}
break;