When either `gnrc_sixlowpan_iphc_nhc` or `gnrc_udp` is not compiled
in `_compressible()` never returns `true`. This causes the
`dispatch` snip in `gnrc_sixlowpan_iphc_send()` to be of length 0,
meaning `dispatch->data` is `NULL`, causing possible crashes when
trying to send IPv6 packets over 6LoWPAN without NHC or UDP.
Loosely based on [the original ping] and [netutil]'s ping
New features (compared to old RIOT version):
- non-positional parameters
- Better duplicate detection (addresses #9387)
- Better asynchronous behavior
- Potential for future move to `sock_ip`
- (Optional) DNS-support
- Multithreading-safe (in case shell-command handler gets called
from multiple threads)
[the original ping]: http://ftp.arl.army.mil/~mike/ping.html
[netutil]: https://www.gnu.org/software/inetutils/
When IPv6 is enabled, the MTU is given. So users(*) sending IPv6 packets can
easily figure out what the supported maximum protocol unit is.
However, when IPv6 is disabled and a user wants to send layer 2 frames directly,
no information about the maximum PDU is available using the shell.
When 6LoWPAN is used, a user may be interested in the layer 2 PDU as well in
order to avoid layer 2 fragmentation.
This PR adds the L2-PDU info to the output of the ifconfig shell command, which
is printed regardless of the use of IPv6.
(*): Here "users" refers to human beings interacting with the shell.
Applications can get the maximum PDU of each layer more easily using
gnrc_netapi_get() with NETOPT_MAX_PACKET_SIZE instead of using a shell command.
This the first step in moving the collection of layer 2 netstats from
the low level driver to a central location, ie. gnrc_netif, to avoid
code duplication.
Currently an interface's existence is not checked when it is supplied
by the user with the `nib` command. This can lead to assertion errors
as soon as the generated entry tries to resolve an address or route
generated with that command and the network interface not being found.
Once the packet buffer is full on heavy network load, gnrc_netif_hdr_build may return NULL. In that case, the following unchecked access to hdr->data leads to a crash.
`gnrc_sixlowpan_frag` internally derives the offset value directly
from the fragment header, so for normal usage within GNRC this
assertion is redundant, but to make the tests of `rbuf_add` 100%
water-tide I added it.
Currently the loop just continues to run after a viable type is found.
In #10851 this lead to a crash of the tests, when the dependency of
`gnrc_sixlowpan` to `gnrc_ipv6` was removed.
When a new queue entry is tried to be allocated for a neighbor who's
address is currently tried to be resolved there was no error case
before. The packet that was tried to be put in the queue was thus not
released and stayed in the packet buffer for ever.
