microschc 0.15.4

Implementation in microPython of SCHC as specified in RFC 8724

microSCHC

In a nutshell

Implementation in microPython of SCHC as specified in RFC 8724 [1].

License

MIT License, Copyright (c) 2022 Orange, by Quentin Lampin

Installing microSCHC

For now, microSCHC is to be built locally using hatch and installed using the wheel (.whl) file generated in the dist/ folder.

build:

hatch build -t wheel

installation:

pip install dist/microschc-<version>-py3-none-any.whl

microSCHC, developpement plan

microSCHC aims at implementing the SCHC Compression/Decompression (C/D) and Fragmentation/Reassembly (F/R) routines described in RFC 8724 [1].

The initial focus of this effort is on the Compression/Decompression (C/D) routines and parsers for typical IoT protocol stacks, i.e. based on IPv6 [2], UDP [3], CoAP [4], lwM2M.

Current features:

1. Parsers
   • IPv4
   • IPv6
   • UDP
   • CoAP (partial test coverage: options missing)
   • CoAP over UDP over IPv6 stack parser
   • lwM2M ( when not using CoAP options, i.e. CoAP payloads) --> postponed to after full SCHC C/D implementation
2. Matching Operators (MO)
   • equal
   • ignore
   • MSB(x)
   • match-mapping
3. Compression/Decompression Actions (CDA)
   1. Compression
      • not-sent
      • value-sent
      • mapping-sent
      • LSB
      • devIID
      • AppIID
      • compute-* (e.g. UDP-checksum)
   2. Decompression counteparts
      • not-sent
      • value-sent
      • mapping-sent
      • LSB
      • devIID
      • AppIID
      • compute-* (e.g. UDP-checksum)
4. Rules
   • rule data model
   • rule matching algorithm
   • YANG model interpreter
5. Compression
   • field (left-)packet
   • field residues concatenation
   • length of variable length field encoding
   • packet compression
6. Context Management
   • Definition & implementation of custom SCHC Context (not specified in RFCs)

• [1] "RFC 8724 SCHC: Generic Framework for Static Context Header Compression and Fragmentation" , A. Minaburo et al.
• [2] "RFC 8200 Internet Protocol, Version 6 (IPv6) Specification, S. Deering et al."
• [3] "RFC 768 User Datagram Protocol, J. Postel"
• [4] "RFC 7252 The Constrained Application Protocol (CoAP), Z. Shelby et al."