It is common to have some data indexed by a name.
If you want to sort a list of such data, you would
have to re-implement your own compare function each time.
Instead, add NMUtilsNamedEntry which as first field has
the name. So, you can create your own struct:
struct my_data {
const char *name;
... other fields
}
and compare them with with nm_utils_named_entry_cmp().
For convenience, add another struct NMUtilsNamedValue, which
has only one data field, a pointer.
This allows the compiler to inline the siphash24*() functions
for nm_hash_ptr() and nm_hash_str() (even without LTO).
This of course only applies to nm_hash_ptr() and nm_hash_str(),
which are implemented in "nm-hash-utils.c" itself. All other
nm_hash_*() functions are inline functions in "nm-hash-utils.h",
and thus these functions can be inlined instead. That is, in
other cases, the nm_hash_*() function instead can be inlined.
For nm_hash_ptr() and nm_hash_str() instead we want to inline the
siphash24*() functions.
So, no longer compile "siphash24.c" directly. Instead, only
build "nm-hash-utils.c" which internally #include "siphash24.c".
Next we will use siphash24() instead of the glib version g_direct_hash() or
g_str_hash(). Hence, the "nm-utils/nm-hash-utils.h" header becomes very
fundamental and will be needed basically everywhere.
Instead of requiring the users to include them, let it be included via
"nm-default.h" header.
siphash24() mixes the bits much better then our naive xor.
Don't bypass siphash24(). We supposedly use it for the
better hashing properties, so use it also for pointers.
When using siphash24(), the hash value depends on the hashed input
and the key from _get_hash_key(). If the input is static, so is also
the result of siphash24(), albeit the bits are scrabbled more.
Add a nm_hash_static() to get such a static key, but without actually
doing siphash24(). The static key is also xored with a static_seed.
For that, also mangle the first byte of the hash key using siphash24()
itself. That is, because nm_hash_static() only uses the first guint of the
random key. Hence, we want that this first guint has all the entropy
of the entire key. We use siphash24() itself, to mangle all bits
of the 16 byte key into the first guint.
The nm_close() wrapper should behave exactly the same as calling
close() directly. This is well known, documented behavior.
The only addition on top of that, should be the nm_assert() to catch
double-closing.
Prevously, when passing a negative file descriptor, we wouldn't properly
set errno. Also, the call would not show up in strace, which it should
(at least, if libc's close actually makes the syscall).
I would argue, that passing a negative file descriptor is a bug already
and we should never do that. Maybe we should even assert non-negative
fds. I don't do that now, because I am not sufficiently confident.
Anyway, the change should have not practical effect, because we
shouldn't actually pass negative fds already.
There is still a fallback detection in "shared/nm-utils/nm-macros-internal.h",
so that VPN-plugins and applet don't need to bother about adding these
configure checks.
The _NM_GET_PRIVATE() macro already preserved and propagated
the constness of @self to the resulting private pointer.
_NM_GET_PRIVATE_PTR() didn't do that. Extend the macro,
to make that possible.
- nm-ovsdb.c uses json_load_callback(), which is jansson v2.4.
Hence, it cannot build the OVS plugin in our Travis-CI, which is
still on Ubuntu Precise. Disable building the plugin in travis and
add a compiler warning when building against an older version.
- since jansson v2.3, there is json_object_key_to_iter() to implement
the for-each macros. Use it in json_object_foreach_safe() when
available.
We need to pass more alias-types. Instead of having numbered
versions, use variadic number of macro arguments.
Also, fix build failure with old compiler:
In file included from src/nm-ip6-config.c:24:
./src/nm-ip6-config.h:44:29: error: controlling expression type 'typeof (ipconf_iter->current->obj)' (aka 'const void *const') not compatible with any generic association type
*out_address = has_next ? NMP_OBJECT_CAST_IP6_ADDRESS (ipconf_iter->current->obj) : NULL;
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fixes: b1810d7a68
_NM_GET_PRIVATE() used typeof() to propagate constness of the @self
pointer. However, that means, it could only be used with a self pointer
of the exact type. That means, you explicitly had to cast from (GObject *)
or from (void *).
The requirement is cumbersome, and often led us to either create @self
pointer we didn't need:
NMDeviceVlan *self = NM_DEVICE_VLAN (device);
NMDeviceVlanPrivate *priv = NM_DEVICE_VLAN_GET_PRIVATE (self);
or casting:
NMDeviceVlanPrivate *priv = NM_DEVICE_VLAN_GET_PRIVATE ((NMDevice *) device);
In both cases we forcefully cast the source variable, loosing help from
the compiler to detect a bug.
For "nm-linux-platform.c", instead we commonly have a pointer of type
NMPlatform. Hence, we always forcefully cast the type via _NM_GET_PRIVATE_VOID().
Rework the macro to use _Generic(). If compiler supports _Generic(), then we
will get all compile time checks as desired. If the compiler doesn't support
_Generic(), it will still work. You don't get the compile-time checking of course,
but you'd notice that something is wrong once you build with a suitable
compiler.
shared/nm-utils/nm-hash-utils.c:110:3: error: right shift count >= width of type [-Werror]
h = h ^ ((guint) (((uintptr_t) ptr) >> 32)) ^ ((guint) ((uintptr_t) ptr));
^
Even if the branch is not reached on 32-bit architectures, the
compiler still emits a warning for the 32-bit right shift.
Fixes: ee76b0979f
nm_close() is like close(), but throws an assertion if the input fd is
>=0 and invalid. Passing an invalid (i.e. already closed) fd to
close() is a programming error with potentially catastrophic effects,
as another thread may reuse the closed fd.
We often want to cascade hashing, meaning, to combine the
outcome of various hash functions in a larger hash.
Instead of having each hash function return a guint hash value,
accept a hash state argument. This saves the overhead of initializing
and completing the intermediate hash states.
It also avoids loosing entropy when we reduce the larger hash state
into the intermediate guint hash value.
By using a macro, we don't cast all the types to guint. Instead,
we use their native types directly. Hence, we don't need
nm_hash_update_uint64() nor nm_hash_update_ptr().
Also, for types smaller then guint like char, we save hashing
the all zero bytes.
siphash24() is wildly used by projects nowadays.
It's certainly slower then our djb hashing that we used before.
But quite likely it's fast enough for us, given how wildly it is
used. I think it would be hard to profile NetworkManager to show
that the performance of hash tables is the issue, be it with
djb or siphash24.
Certainly with siphash24() it's much harder to exploit the hashing
algorithm to cause worst case hash operations (provided that the
seed is kept private). Does this better resistance against a denial
of service matter for us? Probably not, but let's better be safe then
sorry.
Note that systemd's implementation uses a different seed for each hash
table (at least, after the hash table grows to a certain size).
We don't do that and use only one global seed.
The privious NM_HASH_* macros directly operated on a guint value
and were thus close to the actual implementation.
Replace them by adding a NMHashState struct and accessors to
update the hash state. This hides the implementation better
and would allow us to carry more state. For example, we could
switch to siphash24() transparently.
For now, we still do a form basically djb2 hashing, albeit with
differing start seed.
Also add nm_hash_str() and nm_str_hash():
- nm_hash_str() is our own string hashing implementation
- nm_str_hash() is our own string implementation, but with a
GHashFunc signature, suitable to pass it to g_hash_table_new().
Also, it has this name in order to remind you of g_str_hash(),
which it is replacing.
"nm-utils/nm-shared-utils.h" shall contain utility function without other
dependencies. It is intended to be used by other projects as-is.
nm_utils_random_bytes() requires getrandom() and a HAVE_GETRANDOM configure
check. That makes it more cumbersome to re-use "nm-shared-utils.h", in
cases where you don't care about nm_utils_random_bytes().
Split nm_utils_random_bytes() out to a separate file.
Same for hash utils, which depend on nm_utils_random_bytes(). Also, hash
utils will eventually be extended to use siphash24.
This makes hashing non-deterministic with the aim to
make it harder to exploit hash collisions.
Non-deterministic also means that for unit testing
we will get different values on each run. But since we
shall never assign any meaning to these hash values
nor rely on them being stable between restarts (or
upgrades), that doesn't hurt.
Introduce a NM_HASH_INIT() function. It makes the places
where we initialize a hash with a certain seed visually clear.
Also, move them from "shared/nm-utils/nm-shared-utils.h" to
"shared/nm-utils/nm-macros-internal.h". We might want to
have NM_HASH_INIT() non-inline (hence, define it in the
source file).
Add a new function nm_utils_random_bytes().
This function now preferably uses getrandom() syscall if it is
available.
As fallback, it always tries to fill the buffer from /dev/urandom.
If it cannot, as last fallback it uses GRand, which cannot fail.
Hence, the function always sets some (pseudo) random bytes.
It also returns FALSE if the obtained bytes are possibly not good
randomness.
Fixes the following:
shared/nm-utils/nm-shared-utils.c:136: Warning: NetworkManager: GTK-Doc comment block end token "*/" should not be preceded by comment text:
* Returns: the input buffer with the quoted string. */
