def nl_socket_alloc(cb=None):
"""Allocate new Netlink socket. Does not yet actually open a socket.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/socket.c#L206
Also has code for generating local port once.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L123
Keyword arguments:
cb -- custom callback handler.
Returns:
Newly allocated Netlink socket (nl_sock class instance) or None.
"""
# Allocate the callback.
cb = cb or nl_cb_alloc(default_cb)
if not cb:
return None
# Allocate the socket.
sk = nl_sock()
sk.s_cb = cb
sk.s_local.nl_family = getattr(socket, 'AF_NETLINK', -1)
sk.s_peer.nl_family = getattr(socket, 'AF_NETLINK', -1)
sk.s_seq_expect = sk.s_seq_next = int(time.time())
sk.s_flags = NL_OWN_PORT # The port is 0 (unspecified), meaning NL_OWN_PORT.
# Generate local port.
nl_socket_get_local_port(sk) # I didn't find this in the C source, but during testing I saw this behavior.
return sk
def nl_socket_alloc(cb=None):
"""Allocate new Netlink socket. Does not yet actually open a socket.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/socket.c#L206
Also has code for generating local port once.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L123
Keyword arguments:
cb -- custom callback handler.
Returns:
Newly allocated Netlink socket (nl_sock class instance) or None.
"""
# Allocate the callback.
cb = cb or nl_cb_alloc(default_cb)
if not cb:
return None
# Allocate the socket.
sk = nl_sock()
sk.s_cb = cb
sk.s_local.nl_family = getattr(socket, 'AF_NETLINK', -1)
sk.s_peer.nl_family = getattr(socket, 'AF_NETLINK', -1)
sk.s_seq_expect = sk.s_seq_next = int(time.time())
sk.s_flags = NL_OWN_PORT # The port is 0 (unspecified), meaning NL_OWN_PORT.
# Generate local port.
nl_socket_get_local_port(
sk
) # I didn't find this in the C source, but during testing I saw this behavior.
return sk
def test_nl_socket_alloc():
r"""C code to test against.
// gcc a.c $(pkg-config --cflags --libs libnl-genl-3.0) && ./a.out
#include <netlink/msg.h>
struct nl_cb {
nl_recvmsg_msg_cb_t cb_set[NL_CB_TYPE_MAX+1]; void * cb_args[NL_CB_TYPE_MAX+1]; nl_recvmsg_err_cb_t cb_err;
void * cb_err_arg; int (*cb_recvmsgs_ow)(struct nl_sock *, struct nl_cb *);
int (*cb_recv_ow)(struct nl_sock *, struct sockaddr_nl *, unsigned char **, struct ucred **);
int (*cb_send_ow)(struct nl_sock *, struct nl_msg *); int cb_refcnt; enum nl_cb_type cb_active;
};
struct nl_sock {
struct sockaddr_nl s_local; struct sockaddr_nl s_peer; int s_fd; int s_proto; unsigned int s_seq_next;
unsigned int s_seq_expect; int s_flags; struct nl_cb *s_cb; size_t s_bufsize;
};
void print(struct nl_sock *sk) {
printf("sk.s_local.nl_family = %d\n", sk->s_local.nl_family);
printf("sk.s_local.nl_pid = %d # changes every process, remains same throughout proc.\n", sk->s_local.nl_pid);
printf("sk.s_local.nl_groups = %d\n", sk->s_local.nl_groups);
printf("sk.s_peer.nl_family = %d\n", sk->s_peer.nl_family);
printf("sk.s_peer.nl_pid = %d\n", sk->s_peer.nl_pid);
printf("sk.s_peer.nl_groups = %d\n", sk->s_peer.nl_groups);
printf("sk.s_fd = %d\n", sk->s_fd);
printf("sk.s_proto = %d\n", sk->s_proto);
printf("sk.s_flags = %d\n", sk->s_flags);
printf("sk.s_cb.cb_active = %d\n", sk->s_cb->cb_active);
printf("addr: sk.s_cb.cb_err = %p\n", sk->s_cb->cb_err);
}
int main() {
struct nl_sock *sk = nl_socket_alloc();
print(sk);
nl_socket_free(sk);
printf("\n");
struct nl_cb *cb = nl_cb_alloc(NL_CB_VERBOSE);
sk = nl_socket_alloc_cb(cb);
nl_cb_put(cb);
print(sk);
nl_socket_free(sk);
return 0;
}
// Expected output:
// sk.s_local.nl_family = 16
// sk.s_local.nl_pid = 12309 # changes every process, remains same throughout proc.
// sk.s_local.nl_groups = 0
// sk.s_peer.nl_family = 16
// sk.s_peer.nl_pid = 0
// sk.s_peer.nl_groups = 0
// sk.s_fd = -1
// sk.s_proto = 0
// sk.s_flags = 0
// sk.s_cb.cb_active = 11
// addr: sk.s_cb.cb_err = (nil)
//
// sk.s_local.nl_family = 16
// sk.s_local.nl_pid = 12309 # changes every process, remains same throughout proc.
// sk.s_local.nl_groups = 0
// sk.s_peer.nl_family = 16
// sk.s_peer.nl_pid = 0
// sk.s_peer.nl_groups = 0
// sk.s_fd = -1
// sk.s_proto = 0
// sk.s_flags = 0
// sk.s_cb.cb_active = 11
// addr: sk.s_cb.cb_err = 0xb6f6eb40
"""
sk = nl_socket_alloc()
assert 16 == sk.s_local.nl_family
assert 0 < sk.s_local.nl_pid
assert 0 == sk.s_local.nl_groups
assert 16 == sk.s_peer.nl_family
assert 0 == sk.s_peer.nl_pid
assert 0 == sk.s_peer.nl_groups
assert -1 == sk.s_fd
assert 0 == sk.s_proto
assert 0 == sk.s_flags
assert 11 == sk.s_cb.cb_active
assert sk.s_cb.cb_err is None
nl_socket_free(sk)
first_pid = int(sk.s_local.nl_pid)
sk = nl_socket_alloc(nl_cb_alloc(NL_CB_VERBOSE))
assert 16 == sk.s_local.nl_family
assert first_pid == sk.s_local.nl_pid
assert 0 == sk.s_local.nl_groups
assert 16 == sk.s_peer.nl_family
assert 0 == sk.s_peer.nl_pid
assert 0 == sk.s_peer.nl_groups
assert -1 == sk.s_fd
assert 0 == sk.s_proto
assert 0 == sk.s_flags
assert 11 == sk.s_cb.cb_active
assert sk.s_cb.cb_err is not None
nl_socket_free(sk)
def test_nl_socket_alloc():
r"""C code to test against.
// gcc a.c $(pkg-config --cflags --libs libnl-genl-3.0) && ./a.out
#include <netlink/msg.h>
struct nl_cb {
nl_recvmsg_msg_cb_t cb_set[NL_CB_TYPE_MAX+1]; void * cb_args[NL_CB_TYPE_MAX+1]; nl_recvmsg_err_cb_t cb_err;
void * cb_err_arg; int (*cb_recvmsgs_ow)(struct nl_sock *, struct nl_cb *);
int (*cb_recv_ow)(struct nl_sock *, struct sockaddr_nl *, unsigned char **, struct ucred **);
int (*cb_send_ow)(struct nl_sock *, struct nl_msg *); int cb_refcnt; enum nl_cb_type cb_active;
};
struct nl_sock {
struct sockaddr_nl s_local; struct sockaddr_nl s_peer; int s_fd; int s_proto; unsigned int s_seq_next;
unsigned int s_seq_expect; int s_flags; struct nl_cb *s_cb; size_t s_bufsize;
};
void print(struct nl_sock *sk) {
printf("sk.s_local.nl_family = %d\n", sk->s_local.nl_family);
printf("sk.s_local.nl_pid = %d # changes every process, remains same throughout proc.\n", sk->s_local.nl_pid);
printf("sk.s_local.nl_groups = %d\n", sk->s_local.nl_groups);
printf("sk.s_peer.nl_family = %d\n", sk->s_peer.nl_family);
printf("sk.s_peer.nl_pid = %d\n", sk->s_peer.nl_pid);
printf("sk.s_peer.nl_groups = %d\n", sk->s_peer.nl_groups);
printf("sk.s_fd = %d\n", sk->s_fd);
printf("sk.s_proto = %d\n", sk->s_proto);
printf("sk.s_flags = %d\n", sk->s_flags);
printf("sk.s_cb.cb_active = %d\n", sk->s_cb->cb_active);
printf("addr: sk.s_cb.cb_err = %p\n", sk->s_cb->cb_err);
}
int main() {
struct nl_sock *sk = nl_socket_alloc();
print(sk);
nl_socket_free(sk);
printf("\n");
struct nl_cb *cb = nl_cb_alloc(NL_CB_VERBOSE);
sk = nl_socket_alloc_cb(cb);
nl_cb_put(cb);
print(sk);
nl_socket_free(sk);
return 0;
}
// Expected output:
// sk.s_local.nl_family = 16
// sk.s_local.nl_pid = 12309 # changes every process, remains same throughout proc.
// sk.s_local.nl_groups = 0
// sk.s_peer.nl_family = 16
// sk.s_peer.nl_pid = 0
// sk.s_peer.nl_groups = 0
// sk.s_fd = -1
// sk.s_proto = 0
// sk.s_flags = 0
// sk.s_cb.cb_active = 11
// addr: sk.s_cb.cb_err = (nil)
//
// sk.s_local.nl_family = 16
// sk.s_local.nl_pid = 12309 # changes every process, remains same throughout proc.
// sk.s_local.nl_groups = 0
// sk.s_peer.nl_family = 16
// sk.s_peer.nl_pid = 0
// sk.s_peer.nl_groups = 0
// sk.s_fd = -1
// sk.s_proto = 0
// sk.s_flags = 0
// sk.s_cb.cb_active = 11
// addr: sk.s_cb.cb_err = 0xb6f6eb40
"""
sk = nl_socket_alloc()
assert 16 == sk.s_local.nl_family
assert 0 < sk.s_local.nl_pid
assert 0 == sk.s_local.nl_groups
assert 16 == sk.s_peer.nl_family
assert 0 == sk.s_peer.nl_pid
assert 0 == sk.s_peer.nl_groups
assert -1 == sk.s_fd
assert 0 == sk.s_proto
assert 0 == sk.s_flags
assert 11 == sk.s_cb.cb_active
assert sk.s_cb.cb_err is None
nl_socket_free(sk)
first_pid = int(sk.s_local.nl_pid)
sk = nl_socket_alloc(nl_cb_alloc(NL_CB_VERBOSE))
assert 16 == sk.s_local.nl_family
assert first_pid == sk.s_local.nl_pid
assert 0 == sk.s_local.nl_groups
assert 16 == sk.s_peer.nl_family
assert 0 == sk.s_peer.nl_pid
assert 0 == sk.s_peer.nl_groups
assert -1 == sk.s_fd
assert 0 == sk.s_proto
assert 0 == sk.s_flags
assert 11 == sk.s_cb.cb_active
assert sk.s_cb.cb_err is not None
nl_socket_free(sk)
