passt/dhcpv6.c, branch ndebug

treewide: Fix more pointers which can be const

2026-01-14T00:07:51+00:00

Here are some more pointers which can be const, as reported by cppcheck
2.19.1.

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

treewide: Don't rely on terminator records in ip[46].dns arrays

2026-01-10T18:27:45+00:00

In our arrays of DNS resolvers to pass to the guest we use a blank entry
to indicate the end of the list.  We rely on this when scanning the array,
not having separate bounds checking.  clang-tidy 21.1.7 has fancier
checking for array overruns in loops, but it's not able to reason that
there's always a terminating entry, so complains.

Indeed, it's correct to do so in this case.  Although we allow space in the
arrays for the terminator (size MAXNS + 1), add_dns[46]() check only for
    idx >= ARRAY_SIZE()
before adding an entry.  This allows it to consume the last slot with a
"real" entry, meaning the places where we scan really could overrun.

Fix the bug, and make it easier to reason about (for both clang-tidy and
people) by using ARRAY_SIZE() base bounds checking.  Treat the terminator
explicitly as an early exit case using 'break'.

Signed-off-by: David Gibson 
Reviewed-by: Laurent Vivier 
[sbrivio: Fix up comments to @dns in structs ip4_ctx and ip6_ctx]
Signed-off-by: Stefano Brivio

cppcheck: Suppress variable scope warnings in dhcpv6()

2025-10-07T13:33:34+00:00

At least some cppcheck versions (2.18.3 for me) complain that the _storage
variables in dhcpv6() could be reduced in scope.  That's not actually the
case, because although we don't reference the variables, we may touch
their memory via pointers after the blocks in question.  There's no
reasonable way for cppcheck to determine that, though, so suppress its
warnings.

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

dhcpv6: use iov_tail rather than pool

2025-09-03T18:43:41+00:00

This patch refactors the dhcpv6() function to accept `struct iov_tail *data`
directly as its packet input, replacing the `const struct pool *p` parameter.
Consequently, dhcpv6() no longer fetches packet data internally using
packet_data().

This change simplifies callers, such as tap6_handler(), which now pass
the iov_tail representing the L4 UDP segment (DHCPv6 message) directly.
This removes the need for intermediate packet pool handling.

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

packet: rename packet_data() to packet_get()

2025-09-03T18:43:35+00:00

As we have removed packet_get(), we can rename packet_data() to packet_get()
as the name is clearer.

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

dhcpv6: Use iov_tail in dhcpv6_opt()

2025-09-03T18:43:27+00:00

dhcpv6_opt() and its callers are refactored for iov_tail option parsing,
replacing direct offset management for improved robustness.

Its signature is now `bool dhcpv6_opt(iov_tail *data, type)`. `*data` (in/out)
points to a found option on `true` return or is restored on `false`.
The main dhcpv6() function uses IOV_REMOVE_HEADER for the msg_hdr, then
passes the iov_tail (now at options start) to the new dhcpv6_opt().

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

dhcpv6: Convert to iov_tail

2025-09-03T18:43:25+00:00

Use packet_data() and extract headers using IOV_REMOVE_HEADER()
and IOV_PEEK_HEADER() rather than packet_get().

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

dhcpv6: Extract sending of NotOnLink status

2025-09-03T18:43:22+00:00

Extract code from dhcpv6() into a new function, dhcpv6_send_ia_notonlink()

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

dhcpv6: move offset initialization out of dhcpv6_opt()

2025-09-03T18:43:20+00:00

No functional change.

Currently, if dhcpv6_opt() is called with offset set to 0, it will set the
offset to point to DHCPv6 options offset.

To simplify the use of iovec_tail in a later patch, move the initialization
out of the function. Replace all the call using 0 by a call using
the offset of the DHCPv6 options.

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

dhcpv6: fix GCC error (unterminated-string-initialization)

2025-05-14T15:51:20+00:00

The string STR_NOTONLINK is intentionally not NUL-terminated.
Ignore the GCC error using __attribute__((nonstring)).

This error is reported by GCC 15.1.1 on Fedora 42. However,
Clang 20.1.3 does not support __attribute__((nonstring)).
Therefore, NOLINTNEXTLINE(clang-diagnostic-unknown-attributes)
is also added to suppress Clang's unknown attribute warning.

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