While the current approach for garbage collection in the 6Lo reassembly
buffer is good for best-effort handling of
*fragmented* packets and nicely RAM saving, it has the problem that
incomplete, huge datagrams can basically DoS a node, if no further
fragmented datagram is received for a while (since the packet buffer is
full and GC is not triggered).
This change adds a asynchronous GC (utilizing the existing
functionality) to the reassembly buffer, so that even if there is no new
fragmented packet received, fragments older than `RBUF_TIMEOUT` will be
removed from the reassembly buffer, freeing up the otherwise wasted
packet buffer space.
Since IPHC also manipulates the total number of bytes of a received
datagram (by decompressing it), this also needs to be exposed. I guess
I was too focused on introducing a *generic* packet buffer for a future
virtual reassembly buffer (where it isn't needed, but so isn't `pkt` to
be honest), that I totally forgot about it in #9352.
This refactors the `gnrc_sixlowpan_frag` module for the API proposed
in #8511.
The `ctx` for `gnrc_sixlowpan_frag_send()` is required to be a
`gnrc_sixlowpan_msg_frag_t` object, so IPHC can later on use it to
provide the *original* datagram size (otherwise, we would need to adapt
the API just for that, which seems to me as convoluted as this
proposal).
I also provide an expose function with a future possibility to provide
more than just one `gnrc_sixlowpan_msg_frag_t` object later on (plus
having cleaner module separation in general).
This change allows the port for local endpoint to be zero 0. If this is
the case the `sock_udp_create()` function binds the object to an
ephemeral port.
While working on #9352 I noticed that the order of members in the
`gnrc_sixlowpan_msg_frag_t` struct costs us 4 bytes in RAM due to byte
alignment. This PR fixes the order of members, so they are the most
packed.
This exposes the parts of the reassembly buffer to be usable as context
as proposed in #8511.
I only exposed *parts of* for two reasons:
1. I don't need to expose further types (like `rbuf_int_t`), that are
not of interest outside of fragmentation.
2. This allows for an easy future extension for the virtual reassembly
buffer as proposed in [[1]].
This makes this change a little bit more involved, because instead of
just renaming the type, I also need to add the usage of the `super`
member, but I think in the end this little preparation work will be
beneficial in the future.
[1]: https://tools.ietf.org/html/draft-watteyne-6lo-minimal-fragment-01#section-3
While browsing through the rendered doc, I found the precondition of
`gnrc_netreg_register()` somewhat lacking. What is a "message queue"?
`gnrc_netreg_entry_t`s have types. Does this apply for all types?
This specifies the requirement more: The calling thread **only** needs
a message queue (also provides a link to `msg_init_queue()` now for
further information), if the provided `gnrc_netreg_entry_t` is of type
`GNRC_NETREG_TYPE_DEFAULT` (i.e. thread-wise IPC).
Fix re-register when using the same token.
Handle edge cases when change token for a resource.
Only set observer and resource on initial registration.
Discuss re-registration in documentation.
Parts of [RFC4862] were already implemented when NDP via the NIB was
first implemented. This change just includes the DAD portion of
[RFC4862]. This should be enough to make RIOT fully RFC4862 compliant.
[RFC4862]: https://tools.ietf.org/html/rfc4862
The nanocoap_get function is refactored to split of the request part
into a separate function for reuse by other modules. Support for
retransmissions when the received frame is malformed is dropped as it
was broken anyway.
Provides functions for type 3, 4 and 5 UUID generations.
UUID type 1 is timestamp based and requires an accurate time source. For
this reason it is left out of this implementation. UUID type 2 is not
defined in RFC 4122 and thus also not included here
Reordered struct members to not waste memory due to padding.
Before:
``` C
typedef struct {
uint8_t src_l2addr_len;
uint8_t dst_l2addr_len;
kernel_pid_t if_pid; // <-- 16 bit, is aligned to 16 bit
uint8_t flags;
uint8_t __padding_byte; // <-- Inserted to fulfill padding requirements
int16_t rssi; // <-- 16 bit, is NOT aligned to 16 bit
uint8_t lqi;
uint8_t __padding_byte2;// <-- Inserted to fulfill padding requirements
} gnrc_netif_hdr_t;
```
Now:
``` C
typedef struct {
uint8_t src_l2addr_len;
uint8_t dst_l2addr_len;
kernel_pid_t if_pid; // <-- 16 bit, is aligned to 16 bit
uint8_t flags;
uint8_t lqi;
int16_t rssi; // <-- 16 bit, is aligned to 16 bit
} gnrc_netif_hdr_t;
```
When build for the `bluepill` board, the new layout reduces the size by 2 bytes.
Change the API to use int32_t instead of int, to allow for greater
flexibility on 8- and 16-bit platforms. Removed limitation on input
arguments that min < max. Times where it can be useful to have min > max
is when measuring a sensor where a higher measured voltage means a lower
physical value. For example a thermistor can be connected so that the
measured voltage goes down when the temperature goes up.
