Ouch, I accidentally pushed the previous change without running the
tests:

- we need to check, in conf_ports(), that udp_sock_init()
  managed to bind at least a port, not the opposite

- for -T and -U, we have no way to know if we'll manage to bind
  the port later, so never report an error for those

Fixes: 3d0de2c1d727 ("conf, tcp, udp: Exit if we fail to bind sockets for all given ports")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

The newly introduced die() calls exit(), but cppcheck doesn't see it
and warns about possibly invalid arguments used after the check which
triggers die(). Add return statements to silence the warnings.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

This goto exists purely to move this exception case out of line.  Although
that does make the "normal" path a little clearer, it comes at the cost of
not knowing how where control will flow after jumping to the zero_len
label.  The exceptional case isn't that long, so just put it inline.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

This goto can be handled just as simply and more clearly with a do while.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

The goto here really doesn't improve clarity or brevity at all.  Use a
clearer construct.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

In tap_send_frames() we send a number of frames to the tap device, then
also write them to the pcap capture file (if configured).  However the tap
send can partially fail (short write()s or similar), meaning that some
of the requested frames weren't actually sent, but we still write those
frames to the capture file.

We do give a debug message in this case, but it's misleading to add frames
that we know weren't sent to the capture file.  Rework to avoid this.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Based on a patch from Laine, and reports from Laine and Yalan: fix
the "22-80:32-90" example, and improve wording for the other ones:
instead of using "to" to denote the end of a range, use "between ...
and", so that it's clear we're *not* referring to target ports.

Reported-by: Laine Stump <laine@redhat.com>
Reported-by: Yalan Zhang <yalzhang@redhat.com>
Fixes: da20f57f19dc ("passt, qrap: Add man pages")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Similar to the conf_print() fix from commit 4129764ecaeb ("conf: Fix
mask calculation from prefix_len in conf_print()"): to calculate an
IPv4 netmask from the prefix length, we need to left shift 32 all-one
bits by 32 minus the prefix length -- not by the prefix length
itself.

Reported-by: Yalan Zhang <yalzhang@redhat.com>
Fixes: dd09cceaee21 ("Minor improvements to IPv4 netmask handling")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

David points out that using multiple counters to go over the iov
array, namely 'i' and 'iov', makes mistakes easier. We can't just use
'iov', unless we reserve an element with zero iov_len at the end,
which isn't really justified.

Simply use 'i' to iterate over the array.

Link: https://archives.passt.top/passt-dev/Y+mfenvLn3VJ7Dg5@yekko/
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

passt supports ranges of forwarded ports as well as 'all' for TCP and
UDP, so it might be convenient to proceed if we fail to bind only
some of the desired ports.

But if we fail to bind even a single port for a given specification,
we're clearly, unexpectedly, conflicting with another network
service. In that case, report failure and exit.

Reported-by: Yalan Zhang <yalzhang@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>