Instead of retrieving a pointer with NETOPT_STATS, retrieve the current
data. This avoids data corruptions when reading from one thread (e.g.
the thread running the shell (ifconfig command)) while another thread
is updating it (e.g. the netif thread).
The issue affects all boards, as users typically expect the count of
TX packets and the number of TX bytes to refer to the same state. For
16 bit and 8 bit platforms even a single netstat entry can read back
corrupted.
This fixes the issue by just copying the whole netstat_t struct over
without requiring explicit locking on the user side. A multi-threaded
network stack still needs to synchronize the thread responding to
netopt_get with the thread writing to the netstat_t structure, but that
is an implementation detail no relevant to the user of the API.
The netif list is used like a stack, so it needs to be
iterated in reverse to keep the registration order.
Time complexity in O(n^2), but the the list is normally very short
(1-2 items).
Before:
```
> ifconfig
Iface 10 HWaddr: 24:0A:C4:E6:0E:9C Channel: 0 Link: down
[..]
Iface 7 HWaddr: 24:0A:C4:E6:0E:9F Link: down
[..]
```
Now they are in the increasing order:
```
> ifconfig
Iface 7 HWaddr: 24:0A:C4:E6:0E:9F Link: down
[..]
Iface 10 HWaddr: 24:0A:C4:E6:0E:9C Channel: 0 Link: down
[..]
```
When lwIP is hacked to use the same shell command, it also
lists it interfaces in the expected order (was ET1,ET0 before):
```
> ifconfig
Iface ET0 HWaddr: 24:0A:C4:E6:0E:9F Link: down
[..]
Iface ET1 HWaddr: 24:0A:C4:E6:0E:9C Channel: 0 Link: down
[..]
```
The RSSI values reported by LoRa transceiver can be less than -127.
Therefore, `int8_t` is not enough. This commit defines the RSSI of
`netdev_lora_rx_info` as `int16_t` and adapt the drivers accordingly
(sx126x, sx127x).
Currently a valid netif name must be passed to show the usage
instructions:
```
> ifconfig help
error: invalid interface given
> ifconfig 6 help
usage: ifconfig
usage: ifconfig <if_id> [up|down]
[...]
```
`ifconfig --help` is also accepted.
Originally, the options and flags in the `netif` shell output were
separated by two spaces. For later added flags this is not the case,
making the parsing of those flags and options hard to impossible.
This change adds those missing spaces + comments so it might not happen
again in the future.
Previously `ifconfig` would only know link-local addresses
(printed as 'local') and everything else would be 'global'.
This is wrong for site-local and unique local addresses which were
also denoted as global.
So use the already existing helper functions to determine the correct
type of IPv6 address when printing.
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.
