Add support for endpoint-independent mapping ("full cone NAT") in
Libalias's UDP NAT.
This conforms to RFC 4787 requirements 1 and 3. All UDP packets sent out from a
particular internal address:port leave via the same NAT address:port,
regardless of their destination.
Add some libalias tests and supporting defines.
Reviewed by: igoro, thj
Differential Revision: https://reviews.freebsd.org/D46689D
The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.
Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix
Comparing elements in a tree requires transitiviy. If a < b and b < c
then a must be smaller than c. This way the tree elements are always
pairwise comparable.
Tristate comparsion functions returning values lower, equal, or
greater than zero, are usually implemented by a simple subtraction of
the operands. If the size of the operands are equal to the size of
the result, integer modular arithmetics kick in and violates the
transitivity.
Example:
Working on byte with 0, 120, and 240. Now computing the differences:
120 - 0 = 120
240 - 120 = 120
240 - 0 = -16
MFC after: 3 days
Compiling libalias results in warnings about unused functions.
Those warnings are caused by clang's heuristic to consider an inline
function as in use, iff the declaration is in a *.c file.
Declarations in *.h files do not emit those warnings.
Hence the declarations must be moved to an extra *.h file.
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D30844
