gnrc_sixlowpan_iphc: add fragment forwarding stubs

[miri64]

Contribution description

... when VRB is available

This is once again one of these tiny PRs that belong to a bigger PR, @benpicco is always talking about. However, in this case it was already introduced in an earlier version to #11068 (edc9b42) but is now needed also for SFR. So instead of having this piece of code copy-pasted in both, I decided to split it out (even though it is not functional without it).

Testing procedure

There is a test application tests/gnrc_sixlowpan_iphc_w_vrb in this PR that should work on any board that it fits on:

make -C tests/gnrc_sixlowpan_iphc_w_vrb flash test

Confirm that a fragmented and unfragmented UDP packet can still be sent between two 6LoWPAN nodes.

Additionally, you can check-out #11068 and

1. confirm in its history that that PR only adds the actual minimal forwarding steps to gnrc_sixlowpan_iphc.c
2. Run its tests make -C tests/gnrc_sixlowpan_frag_minfwd flash test on a board they fit on

Issues/PRs references

Taken out of #11068's edc9b42 (as it is also required for other 6LoWPAN fragment forwarding schemes like SFR). It is however completely independent of that.

[miri64]

I also added a subroutine to do the actual forwarding in now. This code will be common between #11068 and SFR, so it makes sense to have a common base PR. Currently the function doesn't do anything except for returning -ENOTSUP, but I will provide some patches so it can be tested.

[miri64]

I started a test application. Up until now, only the success case is tested, I plan however to add some failure cases. When setting ENABLE_DEBUG=1 in sys/net/gnrc/network_layer/sixlowpan/iphc/gnrc_sixlowpan_iphc.c one should see something like the following for now:

main(): This is RIOT! (Version: 2020.01-devel-461-g6d46e-gnrc_sixlowpan_iphc/enh/vrb-creation)
.6lo iphc: found route, trying to forward
6lo iphc: Do not know how to forward fragment from (2A:AB:DC:15:54:01:64:79, 15) to (4A:3D:1D:0C:98:31:58:AE, 1)
Original fragmentation header:
00000000  C0  BC  00  0F
IPHC headers + payload:
00000000  7A  00  3A  20  01  0D  B8  00  00  00  00  00  00  00  00  00
00000010  00  00  01  20  01  0D  B8  00  00  00  00  00  00  00  00  00
00000020  00  00  02
00000000  80  00  8E  A0  23  8F  00  02  9D  4B  B2  1C  53  53  53  53
00000010  53  53  53  53  53  53  53  53  53  53  53  53  53  53  53  53
00000020  53  53  53  53  53  53  53  53  53  53  53  53  53  53  53  53
00000030  53  53  53  53  53  53  53  53
packet buffer: first byte: 0x565dc120, last byte: 0x565dc920 (size: 2048)
  position of last byte used: 512
~ unused: 0x565dc120 (next: (nil), size: 2048) ~

OK (1 tests)

[miri64]

Finished tests and squashd. No longer WIP.

[miri64]

Updated the testing procedures

[miri64]

Not really sure why Murdock is failing on native here... I was not able to reproduce this failure locally, neither with GCC nor mit LLVM and I tried it on two systems.

Arch Linux

  Operating System Environment
-----------------------------
       Operating System: "Arch Linux" 
                 Kernel: Linux 5.3.10-arch1-1 x86_64 unknown
Installed compiler toolchains
         native gcc: gcc (GCC) 9.2.0
  arm-none-eabi-gcc: arm-none-eabi-gcc (Arch Repository) 9.2.0
            avr-gcc: avr-gcc (GCC) 9.2.0
   mips-mti-elf-gcc: missing
         msp430-gcc: missing

riscv-none-embed-gcc: missing

xtensa-esp32-elf-gcc: xtensa-esp32-elf-gcc (crosstool-NG crosstool-ng-1.22.0-80-g6c4433a) 5.2.0

xtensa-lx106-elf-gcc: missing

clang: clang version 9.0.0 (tags/RELEASE_900/final)
Installed compiler libs
arm-none-eabi-newlib: "3.1.0"

mips-mti-elf-newlib: missing

riscv-none-embed-newlib: missing

xtensa-esp32-elf-newlib: "2.2.0"

xtensa-lx106-elf-newlib: missing

avr-libc: "2.0.0" ("20150208")
Installed development tools
              cmake: cmake version 3.15.5
           cppcheck: missing
            doxygen: 1.8.16
                git: git version 2.24.0
               make: GNU Make 4.2.1
            openocd: Open On-Chip Debugger 0.10.0+dev-00746-g8f518d35 (2019-03-21-09:43)
             python: Python 3.7.4
            python2: Python 2.7.17
            python3: Python 3.7.4
             flake8: 3.6.0 (mccabe: 0.6.1, pycodestyle: 2.4.0, pyflakes: 2.0.0) CPython 3.7.4 on Linux
         coccinelle: missing

  

Ubuntu 19.10

Operating System Environment
-----------------------------
       Operating System: "Ubuntu" "19.10 (Eoan Ermine)"
                 Kernel: Linux 5.3.0-23-generic x86_64 x86_64
Installed compiler toolchains
         native gcc: gcc (Ubuntu 9.2.1-9ubuntu2) 9.2.1 20191008
  arm-none-eabi-gcc: arm-none-eabi-gcc (GNU Tools for Arm Embedded Processors 8-2018-q4-major) 8.2.1 20181213 (release) [gcc-8-branch revision 267074]
            avr-gcc: avr-gcc (GCC) 5.4.0
   mips-mti-elf-gcc: missing
         msp430-gcc: msp430-gcc (GCC) 4.6.3 20120301 (mspgcc LTS 20120406 unpatched)

riscv-none-embed-gcc: missing

xtensa-esp32-elf-gcc: missing

xtensa-lx106-elf-gcc: missing

clang: clang version 9.0.0-2 (tags/RELEASE_900/final)
Installed compiler libs
arm-none-eabi-newlib: "3.0.0"

mips-mti-elf-newlib: missing

riscv-none-embed-newlib: missing

xtensa-esp32-elf-newlib: missing

xtensa-lx106-elf-newlib: missing

avr-libc: "2.0.0" ("20150208")
Installed development tools
              cmake: cmake version 3.13.4
           cppcheck: missing
            doxygen: 1.8.13
                git: git version 2.20.1
               make: GNU Make 4.2.1
            openocd: Open On-Chip Debugger 0.10.0+dev-00910-g4dbcb1e7 (2019-06-17-16:24)
             python: Python 2.7.17rc1
            python2: Python 2.7.17rc1
            python3: Python 3.7.5rc1
             flake8: 3.7.8 (mccabe: 0.6.1, pycodestyle: 2.5.0, pyflakes: 2.1.1) CPython 3.7.5rc1 on Linux
         coccinelle: missing

  

[benpicco]

tests/gnrc_sixlowpan_iphc_w_vrb is still failing.

Also no review on this one yet, so I guess it's easier for everyone if you just squash.

[miri64]

Mhhhhh... they do work on my machine :-/

[miri64]

Ah, there might be something going wrong with current master rebased. Will check!

[miri64]

First of all: squashed!

[miri64]

(and rebased, though this wasn't my intention ^^")

[miri64]

Fixed. The reason was that the arrival time of the VRB entries that filled the VRB was not set for the VRB-full test, so the garbage collection just through them out when the new entry was created.

[miri64]

Not sure why this worked with the old version of this PR... But now its fixed so 🤷‍♀️

[miri64]

Another update to Makefile.ci (hopefully the last) and squashed directly. Would be great to have this in soonish. Though I tried to make it not to conflict too much with #12879, merging the FF branches with that one was quite hellish ^^"

[benpicco]

Looks good overall, most of it is just adding stub code that doesn't do anything on it's own yet.
b1d4cb3 is a nice small cleanup.

Only found some small things - comments are always good to not get lost in the sea of acronyms.

[miri64]

Addressed comments and squashed directly as otherwise I wouldn't have been able to adapt the comment that was removed in a later commit.

[benpicco]

Code looks good and tests are still passing - changes outside of MODULE_GNRC_SIXLOWPAN_FRAG_VRB are minimal anyway.

[miri64]

Thanks for the review!