[cc2420] Explicitly check the length field #5
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
IEEE 802.15.4 allows data packets of 9-127 bytes and acknowledgements of length 5. This patch adds a check for the received packet length and rejects non-compliant packets. For transmitted packets only 7 bits are considered as packet length and the MSB of the byte holding the length field is reset to zero (to comply with the standard).
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
While experimenting with TinyOS apps in Cooja I experienced unhanded exceptions causing the simulation to terminate. Among other problems I noticed that sometimes the length field of received and transmitted packets was incorrect (too large or too small).
The reasons for this might be different, I identified at least three:
Regardless the reason, it would be nice to handle the incorrect values explicitly.
This patch adds checks of the length field at RX, rejecting all non-compliant packets. At TX it considers only the first seven bits of the length byte as the length field, resetting its MSB to zero, in accordance with IEEE 802.15.4.