passt/pcap.c, branch bug165c

tap: Use iov_tail with tap_add_packet()

2025-09-03T18:42:20+00:00

Use IOV_PEEK_HEADER() to get the ethernet header from the iovec.

Move the workaround about multiple iovec array from vu_handle_tx() to
tap_add_packet(). Removing the offset out of the iovec array should
reduce the iovec count to 1.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

treewide: Flush pcap and log files, if used, before exiting

2025-08-19T14:29:52+00:00

I didn't imagine that occasionally truncated pcap and log files, as a
result of commit d0006fa784a7 ("treewide: use _exit() over exit()"),
would be such a big deal, until I tried to debug TCP issues with this
beauty:

  while true; do ./pasta --trace -l /tmp/pasta.log -p /tmp/pasta.pcap --config-net -t 5555 -- socat TCP-LISTEN:5555 OPEN:/tmp/large.rcv,trunc & (sleep 0.3; socat -T2 OPEN:large.bin TCP:88.198.0.164:5555; ); wait; diff large.bin /tmp/large.rcv || break; done

...flush files and pcap if we're using them. Ignore fsync() errors for
the log file as we obviously can't reliably log them.

Signed-off-by: Stefano Brivio 
Reviewed-by: David Gibson

Correct various function comment headers

2025-06-04T10:32:04+00:00

This commit refines function comment headers for improved accuracy
and consistency. Key changes include:

- Corrected parameter/return descriptions (e.g., `logtime`, `__daemon`).
- Added missing and removed incorrect parameter documentation (e.g.,
  `tcp_vu_sock_recv`, `ndp`).
- Standardized comments to the `/** ... */` style for functions
  like `udp_flow_close` and `ns_enter`.
- Ensured function names in comments consistently use `()`.
- Addressed minor typos and updated comments for renamed functions.

Signed-off-by: Laurent Vivier 
Signed-off-by: Stefano Brivio

pcap: Correctly set snaplen based on tap backend type

2025-03-12T22:08:33+00:00

The pcap header includes a value indicating how much of each frame is
captured.  We always capture the entire frame, so we want to set this to
the maximum possible frame size.  Currently we do that by setting it to
ETH_MAX_MTU, but that's a confusingly named constant which might not always
be correct depending on the details of our tap backend.

Instead add a tap_l2_max_len() function that explicitly returns the maximum
frame size for the current mode and use that to set snaplen.  While we're
there, there's no particular need for the pcap header to be defined in a
global; make it local to pcap_init() instead.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

vhost-user: add vhost-user

2024-11-27T15:47:32+00:00

add virtio and vhost-user functions to connect with QEMU.

  $ ./passt --vhost-user

and

  # qemu-system-x86_64 ... -m 4G \
        -object memory-backend-memfd,id=memfd0,share=on,size=4G \
        -numa node,memdev=memfd0 \
        -chardev socket,id=chr0,path=/tmp/passt_1.socket \
        -netdev vhost-user,id=netdev0,chardev=chr0 \
        -device virtio-net,mac=9a:2b:2c:2d:2e:2f,netdev=netdev0 \
        ...

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
[sbrivio: as suggested by lvivier, include 
 before including  as C libraries such as musl
 __UAPI_DEF_ETHHDR in  if they already have
 a definition of struct ethhdr]
Signed-off-by: Stefano Brivio

treewide: Address cert-err33-c clang-tidy warnings for clock and timer functions

2024-10-30T11:37:31+00:00

For clock_gettime(), we shouldn't ignore errors if they happen at
initialisation phase, because something is seriously wrong and it's
not helpful if we proceed as if nothing happened.

As we're up and running, though, it's probably better to report the
error and use a stale value than to terminate altogether. Make sure
we use a zero value if we don't have a stale one somewhere.

For timerfd_gettime() and timerfd_settime() failures, just report an
error, there isn't much else we can do.

Signed-off-by: Stefano Brivio

treewide: Suppress clang-tidy warning if we already use O_CLOEXEC

2024-10-30T11:37:31+00:00

In pcap_init(), we should always open the packet capture file with
O_CLOEXEC, even if we're not running in foreground: O_CLOEXEC means
close-on-exec, not close-on-fork.

In logfile_init() and pidfile_open(), the fact that we pass a third
'mode' argument to open() seems to confuse the android-cloexec-open
checker in LLVM versions from 16 to 19 (at least).

The checker is suggesting to add O_CLOEXEC to 'mode', and not in
'flags', where we already have it.

Add a suppression for clang-tidy and a comment, and avoid repeating
those three times by adding a new helper, output_file_open().

Signed-off-by: Stefano Brivio

pcap: Add an offset argument in pcap_iov()

2024-10-04T12:51:02+00:00

The offset is passed directly to pcap_frame() and allows
any headers that are not part of the frame to
capture to be skipped.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

util: Add helper to write() all of a buffer

2024-09-18T15:14:59+00:00

write(2) might not write all the data it is given.  Add a write_all_buf()
helper to keep calling it until all the given data is written, or we get an
error.

Currently we use write_remainder() to do this operation in pcap_frame().
That's a little awkward since it requires constructing an iovec, and future
changes we want to make to write_remainder() will be easier in terms of
this single buffer helper.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

treewide: Replace strerror() calls

2024-06-21T13:32:44+00:00

Now that we have logging functions embedding perror() functionality,
we can make _some_ calls more terse by using them. In many places,
the strerror() calls are still more convenient because, for example,
they are used in flow debugging functions, or because the return code
variable of interest is not 'errno'.

While at it, convert a few error messages from a scant perror style
to proper failure descriptions.

Signed-off-by: Stefano Brivio 
Reviewed-by: David Gibson