The behaviour without tcpi_snd_wnd changed: the only difference now
is the advertised window, which corresponds to the queried sending
buffer size.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Move netlink routines to their own file, and use netlink to configure
or fetch all the information we need, except for the TUNSETIFF ioctl.
Move pasta-specific functions to their own file as well, add
parameters and calls to configure the tap interface in the namespace.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
getifaddrs() needs to allocate heap memory, and gets a ton of results
we don't need. Use explicit netlink messages with "strict checking"
instead.
While at it, separate L2/L3 address handling, so that we don't fetch
MAC addresses for IPv6, and also use netlink instead of ioctl() to
get the MAC address.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
We usually have up to one additional child exiting while we receive
a SIGCHLD, instead of complicating this with tracking PIDs, just
add a second waitid() call.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Based on a patch from Giuseppe Scrivano, this adds the ability to:
- specify paths and names of target namespaces to join, instead of
a PID, also for user namespaces, with --userns
- request to join or create a network namespace only, without
entering or creating a user namespace, with --netns-only
- specify the base directory for netns mountpoints, with --nsrun-dir
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
[sbrivio: reworked logic to actually join the given namespaces when
they're not created, implemented --netns-only and --nsrun-dir,
updated pasta demo script and man page]
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
That's the first thing we have to do, before sending SYN, ACK:
if tcp_send_to_tap() fails, we'll get a lot of useless events
otherwise.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Now that we have a proper function checking when and how to send
ACKs and window updates, we don't need to duplicate this logic in
tcp_data_from_tap().
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
...using pre-cooked buffers, just like we do with other segments.
While at it, remove some code duplication by having separate
functions for updating ACK sequence and window, and for filling in
buffer headers.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
We'll need this for TCP ACK coalescing on tap/guest-side. For
convenience, allow _handler() functions to be undefined, courtesy
of __attribute__((weak)).
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Now that we fixed the issue with small receiving buffers, we can
safely increase this back and get slightly lower syscall overhead.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
If net.core.rmem_max and net.core.wmem_max sysctls have low values,
we can get bigger buffers by not trying to set them high -- the
kernel would lock their values to what we get.
Try, instead, to get bigger buffers by queueing as much as possible,
and if maximum values in tcp_wmem and tcp_rmem are bigger than this,
that will work.
While at it, drop QUICKACK option for non-spliced sockets, I set
that earlier by mistake.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
If the connection is local or the RTT was comparable to the time it
takes to queue a batch of messages, we can safely use a large MSS
regardless of the sending buffer, but otherwise not.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
If we start with a very small sending buffer, we can make the kernel
expand it if we cause the congestion window to get bigger, but this
won't reliably happen if we use just half (other half is accounted
as overhead).
Scale usage depending on its own size, we might eventually get some
retransmissions because we can't queue messages the sender sends us
in-window, but it's better than keeping that small buffer forever.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
...and from the sending socket only if the MTU is not configured.
Otherwise, a connection to a host from a local guest, with a
non-loopback destination address, will get its MSS from the MTU of the
outbound interface with that address, which is unnecessary as we know
the guest can send us larger segments.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Detecting bound ports at start-up time isn't terribly useful: do this
periodically instead, if configured.
This is only implemented for TCP at the moment, UDP is somewhat more
complicated: leave a TODO there.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This introduces a number of fundamental changes that would be quite
messy to split. Summary:
- advertised window scaling can be as big as we want, we just need
to clamp window sizes to avoid exceeding the size of our "discard"
buffer for unacknowledged data from socket
- add macros to compare sequence numbers
- force sending ACK to guest/tap on PSH segments, always in pasta
mode, whenever we see an overlapping segment, or when we reach a
given threshold compared to our window
- we don't actually use recvmmsg() here, fix comments and label
- introduce pools for pre-opened sockets and pipes, to decrease
latency on new connections
- set receiving and sending buffer sizes to the maximum allowed,
kernel will clamp and round appropriately
- defer clean-up of spliced and non-spliced connection to timer
- in tcp_send_to_tap(), there's no need anymore to keep a large
buffer, shrink it down to what we actually need
- introduce SO_RCVLOWAT setting and activity tracking for spliced
connections, to coalesce data moved by splice() calls as much as
possible
- as we now have a compacted connection table, there's no need to
keep sparse bitmaps tracking connection activity -- simply go
through active connections with a loop in the timer handler
- always clamp the advertised window to half our sending buffer,
too, to minimise retransmissions from the guest/tap
- set TCP_QUICKACK for originating socket in spliced connections,
there's no need to delay them
- fix up timeout for unacknowledged data from socket
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
In case we need to reinitialise the tap interface, make that
relatively transparent to processes running in the namespace.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
passt is stable enough, and dropping O_DSYNC makes reduces the impact
of capturing packets on timing, while running tests.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
If the guest disconnects, and a given name (without timestamp) for
the pcap file is passed, we would otherwise lose the packets
captured until that point.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
