def nl_socket_set_buffer_size(sk, rxbuf, txbuf):
"""Set socket buffer size of Netlink socket.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/socket.c#L675
Sets the socket buffer size of a Netlink socket to the specified values `rxbuf` and `txbuf`. Providing a value of 0
assumes a good default value.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
rxbuf -- new receive socket buffer size in bytes (integer).
txbuf -- new transmit socket buffer size in bytes (integer).
Returns:
0 on success or a negative error code.
"""
rxbuf = 32768 if rxbuf <= 0 else rxbuf
txbuf = 32768 if txbuf <= 0 else txbuf
if sk.s_fd == -1:
return -NLE_BAD_SOCK
try:
sk.socket_instance.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF,
txbuf)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
try:
sk.socket_instance.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF,
rxbuf)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
sk.s_flags |= NL_SOCK_BUFSIZE_SET
return 0
def nl_socket_set_buffer_size(sk, rxbuf, txbuf):
"""Set socket buffer size of Netlink socket.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/socket.c#L675
Sets the socket buffer size of a Netlink socket to the specified values `rxbuf` and `txbuf`. Providing a value of 0
assumes a good default value.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
rxbuf -- new receive socket buffer size in bytes (integer).
txbuf -- new transmit socket buffer size in bytes (integer).
Returns:
0 on success or a negative error code.
"""
rxbuf = 32768 if rxbuf <= 0 else rxbuf
txbuf = 32768 if txbuf <= 0 else txbuf
if sk.s_fd == -1:
return -NLE_BAD_SOCK
try:
sk.socket_instance.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, txbuf)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
try:
sk.socket_instance.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, rxbuf)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
sk.s_flags |= NL_SOCK_BUFSIZE_SET
return 0
def nl_socket_drop_memberships(sk, *group):
"""Leave groups.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/socket.c#L465
Leaves the specified groups using the modern socket option. The list of groups has to terminated by 0.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
group -- group identifier (integer).
Returns:
0 on success or a negative error code.
"""
if sk.s_fd == -1:
return -NLE_BAD_SOCK
for grp in group:
if not grp:
break
if grp < 0:
return -NLE_INVAL
try:
sk.socket_instance.setsockopt(SOL_NETLINK, NETLINK_DROP_MEMBERSHIP, grp)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
return 0
def nl_socket_add_memberships(sk, *group):
"""Join groups.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/socket.c#L417
Joins the specified groups using the modern socket option. The list of groups has to be terminated by 0.
Make sure to use the correct group definitions as the older bitmask definitions for nl_join_groups() are likely to
still be present for backward compatibility reasons.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
group -- group identifier (integer).
Returns:
0 on success or a negative error code.
"""
if sk.s_fd == -1:
return -NLE_BAD_SOCK
for grp in group:
if not grp:
break
if grp < 0:
return -NLE_INVAL
try:
sk.socket_instance.setsockopt(SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, grp)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
return 0
def nl_socket_add_memberships(sk, *group):
"""Join groups.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/socket.c#L417
Joins the specified groups using the modern socket option. The list of groups has to be terminated by 0.
Make sure to use the correct group definitions as the older bitmask definitions for nl_join_groups() are likely to
still be present for backward compatibility reasons.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
group -- group identifier (integer).
Returns:
0 on success or a negative error code.
"""
if sk.s_fd == -1:
return -NLE_BAD_SOCK
for grp in group:
if not grp:
break
if grp < 0:
return -NLE_INVAL
try:
sk.socket_instance.setsockopt(SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
grp)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
return 0
def nl_socket_drop_memberships(sk, *group):
"""Leave groups.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/socket.c#L465
Leaves the specified groups using the modern socket option. The list of groups has to terminated by 0.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
group -- group identifier (integer).
Returns:
0 on success or a negative error code.
"""
if sk.s_fd == -1:
return -NLE_BAD_SOCK
for grp in group:
if not grp:
break
if grp < 0:
return -NLE_INVAL
try:
sk.socket_instance.setsockopt(SOL_NETLINK, NETLINK_DROP_MEMBERSHIP,
grp)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
return 0
def nl_sendmsg(sk, msg, hdr):
"""Transmit Netlink message using socket.sendmsg|sendto|send().
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L299
Transmits the message specified in `hdr` over the Netlink socket using Python's socket.sendmsg().
ATTENTION: The `msg` argument will *not* be used to derive the message payload that is being sent out. The `msg`
argument is *only* passed on to the `NL_CB_MSG_OUT` callback. The caller is responsible to initialize the `hdr`
struct properly and have it point to the message payload and socket address.
This function uses `nlmsg_set_src()` to modify the `msg` argument prior to invoking the `NL_CB_MSG_OUT` callback to
provide the local port number.
This function triggers the `NL_CB_MSG_OUT` callback.
ATTENTION: Think twice before using this function. It provides a low level access to the Netlink socket. Among other
limitations, it does not add credentials even if enabled or respect the destination address specified in the `msg`
object.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
msg -- Netlink message to be sent (nl_msg class instance).
hdr -- sendmsg() message header (msghdr class instance).
Returns:
Number of bytes sent on success or a negative error code.
"""
if sk.s_fd < 0:
return -NLE_BAD_SOCK
nlmsg_set_src(msg, sk.s_local)
cb = sk.s_cb
if cb.cb_set[NL_CB_MSG_OUT]:
ret = nl_cb_call(cb, NL_CB_MSG_OUT, msg)
if ret != NL_OK:
return ret
if hdr.msg_name is None:
address = None
else:
address = tuple(hdr.msg_name)
if address == (0, 0) or address == sk.socket_instance.getsockname:
address = None
try:
if hdr.msg_control:
ret = sk.socket_instance.sendmsg([hdr.msg_iov], hdr.msg_control,
hdr.msg_flags, address)
elif address:
ret = sk.socket_instance.sendto(hdr.msg_iov, hdr.msg_flags,
address)
else:
ret = sk.socket_instance.send(hdr.msg_iov, hdr.msg_flags)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
_LOGGER.debug('sent %d bytes', ret)
return ret
def nl_sendmsg(sk, msg, hdr):
"""Transmit Netlink message using socket.sendmsg|sendto|send().
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L299
Transmits the message specified in `hdr` over the Netlink socket using Python's socket.sendmsg().
ATTENTION: The `msg` argument will *not* be used to derive the message payload that is being sent out. The `msg`
argument is *only* passed on to the `NL_CB_MSG_OUT` callback. The caller is responsible to initialize the `hdr`
struct properly and have it point to the message payload and socket address.
This function uses `nlmsg_set_src()` to modify the `msg` argument prior to invoking the `NL_CB_MSG_OUT` callback to
provide the local port number.
This function triggers the `NL_CB_MSG_OUT` callback.
ATTENTION: Think twice before using this function. It provides a low level access to the Netlink socket. Among other
limitations, it does not add credentials even if enabled or respect the destination address specified in the `msg`
object.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
msg -- Netlink message to be sent (nl_msg class instance).
hdr -- sendmsg() message header (msghdr class instance).
Returns:
Number of bytes sent on success or a negative error code.
"""
if sk.s_fd < 0:
return -NLE_BAD_SOCK
nlmsg_set_src(msg, sk.s_local)
cb = sk.s_cb
if cb.cb_set[NL_CB_MSG_OUT]:
ret = nl_cb_call(cb, NL_CB_MSG_OUT, msg)
if ret != NL_OK:
return ret
if hdr.msg_name is None:
address = None
else:
address = tuple(hdr.msg_name)
if address == (0, 0) or address == sk.socket_instance.getsockname:
address = None
try:
if hdr.msg_control:
ret = sk.socket_instance.sendmsg([hdr.msg_iov], hdr.msg_control, hdr.msg_flags, address)
elif address:
ret = sk.socket_instance.sendto(hdr.msg_iov, hdr.msg_flags, address)
else:
ret = sk.socket_instance.send(hdr.msg_iov, hdr.msg_flags)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
_LOGGER.debug('sent %d bytes', ret)
return ret
def nl_connect(sk, protocol):
"""Create file descriptor and bind socket.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L96
Creates a new Netlink socket using `socket.socket()` and binds the socket to the protocol and local port specified
in the `sk` socket object (if any). Fails if the socket is already connected.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
protocol -- Netlink protocol to use (integer).
Returns:
0 on success or a negative error code.
"""
flags = getattr(socket, 'SOCK_CLOEXEC', 0)
if sk.s_fd != -1:
return -NLE_BAD_SOCK
try:
sk.socket_instance = socket.socket(getattr(socket, 'AF_NETLINK', -1),
socket.SOCK_RAW | flags, protocol)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
if not sk.s_flags & NL_SOCK_BUFSIZE_SET:
err = nl_socket_set_buffer_size(sk, 0, 0)
if err < 0:
sk.socket_instance.close()
return err
try:
sk.socket_instance.bind((sk.s_local.nl_pid, sk.s_local.nl_groups))
except OSError as exc:
sk.socket_instance.close()
return -nl_syserr2nlerr(exc.errno)
sk.s_local.nl_pid = sk.socket_instance.getsockname()[0]
if sk.s_local.nl_family != socket.AF_NETLINK:
sk.socket_instance.close()
return -NLE_AF_NOSUPPORT
sk.s_proto = protocol
return 0
def nl_connect(sk, protocol):
"""Create file descriptor and bind socket.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L96
Creates a new Netlink socket using `socket.socket()` and binds the socket to the protocol and local port specified
in the `sk` socket object (if any). Fails if the socket is already connected.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
protocol -- Netlink protocol to use (integer).
Returns:
0 on success or a negative error code.
"""
flags = getattr(socket, 'SOCK_CLOEXEC', 0)
if sk.s_fd != -1:
return -NLE_BAD_SOCK
try:
sk.socket_instance = socket.socket(getattr(socket, 'AF_NETLINK', -1), socket.SOCK_RAW | flags, protocol)
except OSError as exc:
return -nl_syserr2nlerr(exc.errno)
if not sk.s_flags & NL_SOCK_BUFSIZE_SET:
err = nl_socket_set_buffer_size(sk, 0, 0)
if err < 0:
sk.socket_instance.close()
return err
try:
sk.socket_instance.bind((sk.s_local.nl_pid, sk.s_local.nl_groups))
except OSError as exc:
sk.socket_instance.close()
return -nl_syserr2nlerr(exc.errno)
sk.s_local.nl_pid = sk.socket_instance.getsockname()[0]
if sk.s_local.nl_family != socket.AF_NETLINK:
sk.socket_instance.close()
return -NLE_AF_NOSUPPORT
sk.s_proto = protocol
return 0
def recvmsgs(sk, cb):
"""https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L775.
This is where callbacks are called.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
cb -- callbacks (nl_cb class instance).
Returns:
Number of bytes received or a negative error code.
"""
multipart = 0
interrupted = 0
nrecv = 0
buf = bytearray()
# nla is passed on to not only to nl_recv() but may also be passed to a function pointer provided by the caller
# which may or may not initialize the variable. Thomas Graf.
nla = sockaddr_nl()
creds = ucred()
while True: # This is the `goto continue_reading` implementation.
_LOGGER.debug('Attempting to read from 0x%x', id(sk))
n = c_int(
cb.cb_recv_ow(sk, nla, buf, creds) if cb.
cb_recv_ow else nl_recv(sk, nla, buf, creds))
if n.value <= 0:
return n.value
_LOGGER.debug('recvmsgs(0x%x): Read %d bytes', id(sk), n.value)
hdr = nlmsghdr(bytearray_ptr(buf))
while nlmsg_ok(hdr, n):
_LOGGER.debug('recvmsgs(0x%x): Processing valid message...',
id(sk))
msg = nlmsg_convert(hdr)
nlmsg_set_proto(msg, sk.s_proto)
nlmsg_set_src(msg, nla)
if creds:
raise NotImplementedError # nlmsg_set_creds(msg, creds)
nrecv += 1
# Raw callback is the first, it gives the most control to the user and he can do his very own parsing.
if cb.cb_set[NL_CB_MSG_IN]:
err = nl_cb_call(cb, NL_CB_MSG_IN,
msg) # NL_CB_CALL(cb, NL_CB_MSG_IN, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
if cb.cb_set[NL_CB_SEQ_CHECK]:
# Sequence number checking. The check may be done by the user, otherwise a very simple check is applied
# enforcing strict ordering.
err = nl_cb_call(cb, NL_CB_SEQ_CHECK,
msg) # NL_CB_CALL(cb, NL_CB_SEQ_CHECK, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
elif not sk.s_flags & NL_NO_AUTO_ACK:
# Only do sequence checking if auto-ack mode is enabled.
if hdr.nlmsg_seq != sk.s_seq_expect:
if cb.cb_set[NL_CB_INVALID]:
err = nl_cb_call(
cb, NL_CB_INVALID,
msg) # NL_CB_CALL(cb, NL_CB_INVALID, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (
err or nrecv)
else:
return -NLE_SEQ_MISMATCH
if hdr.nlmsg_type in (NLMSG_DONE, NLMSG_ERROR, NLMSG_NOOP,
NLMSG_OVERRUN):
# We can't check for !NLM_F_MULTI since some Netlink users in the kernel are broken.
sk.s_seq_expect += 1
_LOGGER.debug(
'recvmsgs(0x%x): Increased expected sequence number to %d',
id(sk), sk.s_seq_expect)
if hdr.nlmsg_flags & NLM_F_MULTI:
multipart = 1
if hdr.nlmsg_flags & NLM_F_DUMP_INTR:
if cb.cb_set[NL_CB_DUMP_INTR]:
err = nl_cb_call(
cb, NL_CB_DUMP_INTR,
msg) # NL_CB_CALL(cb, NL_CB_DUMP_INTR, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err
or nrecv)
else:
# We have to continue reading to clear all messages until a NLMSG_DONE is received and report the
# inconsistency.
interrupted = 1
if hdr.nlmsg_flags & NLM_F_ACK:
# Other side wishes to see an ack for this message.
if cb.cb_set[NL_CB_SEND_ACK]:
err = nl_cb_call(
cb, NL_CB_SEND_ACK,
msg) # NL_CB_CALL(cb, NL_CB_SEND_ACK, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err
or nrecv)
if hdr.nlmsg_type == NLMSG_DONE:
# Messages terminates a multipart message, this is usually the end of a message and therefore we slip
# out of the loop by default. the user may overrule this action by skipping this packet.
multipart = 0
if cb.cb_set[NL_CB_FINISH]:
err = nl_cb_call(cb, NL_CB_FINISH,
msg) # NL_CB_CALL(cb, NL_CB_FINISH, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err
or nrecv)
elif hdr.nlmsg_type == NLMSG_NOOP:
# Message to be ignored, the default action is to skip this message if no callback is specified. The
# user may overrule this action by returning NL_PROCEED.
if cb.cb_set[NL_CB_SKIPPED]:
err = nl_cb_call(cb, NL_CB_SKIPPED,
msg) # NL_CB_CALL(cb, NL_CB_SKIPPED, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err
or nrecv)
else:
hdr = nlmsg_next(hdr, n)
continue
elif hdr.nlmsg_type == NLMSG_OVERRUN:
# Data got lost, report back to user. The default action is to quit parsing. The user may overrule this
# action by retuning NL_SKIP or NL_PROCEED (dangerous).
if cb.cb_set[NL_CB_OVERRUN]:
err = nl_cb_call(cb, NL_CB_OVERRUN,
msg) # NL_CB_CALL(cb, NL_CB_OVERRUN, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err
or nrecv)
else:
return -NLE_DUMP_INTR if interrupted else -NLE_MSG_OVERFLOW
elif hdr.nlmsg_type == NLMSG_ERROR:
# Message carries a nlmsgerr.
e = nlmsgerr(nlmsg_data(hdr))
if hdr.nlmsg_len < nlmsg_size(e.SIZEOF):
# Truncated error message, the default action is to stop parsing. The user may overrule this action
# by returning NL_SKIP or NL_PROCEED (dangerous).
if cb.cb_set[NL_CB_INVALID]:
err = nl_cb_call(
cb, NL_CB_INVALID,
msg) # NL_CB_CALL(cb, NL_CB_INVALID, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (
err or nrecv)
else:
return -NLE_DUMP_INTR if interrupted else -NLE_MSG_TRUNC
elif e.error:
# Error message reported back from kernel.
if cb.cb_err:
err = cb.cb_err(nla, e, cb.cb_err_arg)
if err < 0:
return -NLE_DUMP_INTR if interrupted else err
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else -nl_syserr2nlerr(
e.error)
else:
return -NLE_DUMP_INTR if interrupted else -nl_syserr2nlerr(
e.error)
elif cb.cb_set[NL_CB_ACK]:
err = nl_cb_call(cb, NL_CB_ACK,
msg) # NL_CB_CALL(cb, NL_CB_ACK, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err
or nrecv)
else:
# Valid message (not checking for MULTIPART bit to get along with broken kernels. NL_SKIP has no effect
# on this.
if cb.cb_set[NL_CB_VALID]:
err = nl_cb_call(cb, NL_CB_VALID,
msg) # NL_CB_CALL(cb, NL_CB_VALID, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err
or nrecv)
hdr = nlmsg_next(hdr, n)
del buf[:]
creds = None
if multipart:
# Multipart message not yet complete, continue reading.
continue
err = 0
if interrupted:
return -NLE_DUMP_INTR
if not err:
err = nrecv
return err
def nl_recv(sk, nla, buf, creds=None):
"""Receive data from Netlink socket.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L625
Receives data from a connected netlink socket using recvmsg() and returns the number of bytes read. The read data is
stored in a newly allocated buffer that is assigned to `buf`. The peer's netlink address will be stored in `nla`.
This function blocks until data is available to be read unless the socket has been put into non-blocking mode using
nl_socket_set_nonblocking() in which case this function will return immediately with a return value of 0.
The buffer size used when reading from the netlink socket and thus limiting the maximum size of a netlink message
that can be read defaults to the size of a memory page (getpagesize()). The buffer size can be modified on a per
socket level using the function `nl_socket_set_msg_buf_size()`.
If message peeking is enabled using nl_socket_enable_msg_peek() the size of the message to be read will be
determined using the MSG_PEEK flag prior to performing the actual read. This leads to an additional recvmsg() call
for every read operation which has performance implications and is not recommended for high throughput protocols.
An eventual interruption of the recvmsg() system call is automatically handled by retrying the operation.
If receiving of credentials has been enabled using the function `nl_socket_set_passcred()`, this function will
allocate a new struct `ucred` filled with the received credentials and assign it to `creds`.
Positional arguments:
sk -- Netlink socket (nl_sock class instance) (input).
nla -- Netlink socket structure to hold address of peer (sockaddr_nl class instance) (output).
buf -- destination bytearray() for message content (output).
creds -- destination class instance for credentials (ucred class instance) (output).
Returns:
Two-item tuple. First item is number of bytes read, 0 on EOF, 0 on no data event (non-blocking mode), or a negative
error code. Second item is the message content from the socket or None.
"""
flags = 0
page_size = resource.getpagesize() * 4
if sk.s_flags & NL_MSG_PEEK:
flags |= socket.MSG_PEEK | socket.MSG_TRUNC
iov_len = sk.s_bufsize or page_size
if creds and sk.s_flags & NL_SOCK_PASSCRED:
raise NotImplementedError # TODO https://github.com/Robpol86/libnl/issues/2
while True: # This is the `goto retry` implementation.
try:
if hasattr(sk.socket_instance, 'recvmsg'):
iov, _, msg_flags, address = sk.socket_instance.recvmsg(
iov_len, 0, flags)
else:
iov, address = sk.socket_instance.recvfrom(iov_len, flags)
msg_flags = 0
except OSError as exc:
if exc.errno == errno.EINTR:
continue # recvmsg() returned EINTR, retrying.
return -nl_syserr2nlerr(exc.errno)
nla.nl_family = sk.socket_instance.family # recvmsg() in C does this, but not Python's.
if not iov:
return 0
if msg_flags & socket.MSG_CTRUNC:
raise NotImplementedError # TODO https://github.com/Robpol86/libnl/issues/2
if iov_len < len(iov) or msg_flags & socket.MSG_TRUNC:
# Provided buffer is not long enough.
# Enlarge it to size of n (which should be total length of the message) and try again.
iov_len = len(iov)
continue
if flags:
# Buffer is big enough, do the actual reading.
flags = 0
continue
nla.nl_pid = address[0]
nla.nl_groups = address[1]
if creds and sk.s_flags * NL_SOCK_PASSCRED:
raise NotImplementedError # TODO https://github.com/Robpol86/libnl/issues/2
if iov:
buf += iov
return len(buf)
def recvmsgs(sk, cb):
"""https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L775.
This is where callbacks are called.
Positional arguments:
sk -- Netlink socket (nl_sock class instance).
cb -- callbacks (nl_cb class instance).
Returns:
Number of bytes received or a negative error code.
"""
multipart = 0
interrupted = 0
nrecv = 0
buf = bytearray()
# nla is passed on to not only to nl_recv() but may also be passed to a function pointer provided by the caller
# which may or may not initialize the variable. Thomas Graf.
nla = sockaddr_nl()
creds = ucred()
while True: # This is the `goto continue_reading` implementation.
_LOGGER.debug('Attempting to read from 0x%x', id(sk))
n = c_int(cb.cb_recv_ow(sk, nla, buf, creds) if cb.cb_recv_ow else nl_recv(sk, nla, buf, creds))
if n.value <= 0:
return n.value
_LOGGER.debug('recvmsgs(0x%x): Read %d bytes', id(sk), n.value)
hdr = nlmsghdr(bytearray_ptr(buf))
while nlmsg_ok(hdr, n):
_LOGGER.debug('recvmsgs(0x%x): Processing valid message...', id(sk))
msg = nlmsg_convert(hdr)
nlmsg_set_proto(msg, sk.s_proto)
nlmsg_set_src(msg, nla)
if creds:
raise NotImplementedError # nlmsg_set_creds(msg, creds)
nrecv += 1
# Raw callback is the first, it gives the most control to the user and he can do his very own parsing.
if cb.cb_set[NL_CB_MSG_IN]:
err = nl_cb_call(cb, NL_CB_MSG_IN, msg) # NL_CB_CALL(cb, NL_CB_MSG_IN, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
if cb.cb_set[NL_CB_SEQ_CHECK]:
# Sequence number checking. The check may be done by the user, otherwise a very simple check is applied
# enforcing strict ordering.
err = nl_cb_call(cb, NL_CB_SEQ_CHECK, msg) # NL_CB_CALL(cb, NL_CB_SEQ_CHECK, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
elif not sk.s_flags & NL_NO_AUTO_ACK:
# Only do sequence checking if auto-ack mode is enabled.
if hdr.nlmsg_seq != sk.s_seq_expect:
if cb.cb_set[NL_CB_INVALID]:
err = nl_cb_call(cb, NL_CB_INVALID, msg) # NL_CB_CALL(cb, NL_CB_INVALID, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
else:
return -NLE_SEQ_MISMATCH
if hdr.nlmsg_type in (NLMSG_DONE, NLMSG_ERROR, NLMSG_NOOP, NLMSG_OVERRUN):
# We can't check for !NLM_F_MULTI since some Netlink users in the kernel are broken.
sk.s_seq_expect += 1
_LOGGER.debug('recvmsgs(0x%x): Increased expected sequence number to %d', id(sk), sk.s_seq_expect)
if hdr.nlmsg_flags & NLM_F_MULTI:
multipart = 1
if hdr.nlmsg_flags & NLM_F_DUMP_INTR:
if cb.cb_set[NL_CB_DUMP_INTR]:
err = nl_cb_call(cb, NL_CB_DUMP_INTR, msg) # NL_CB_CALL(cb, NL_CB_DUMP_INTR, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
else:
# We have to continue reading to clear all messages until a NLMSG_DONE is received and report the
# inconsistency.
interrupted = 1
if hdr.nlmsg_flags & NLM_F_ACK:
# Other side wishes to see an ack for this message.
if cb.cb_set[NL_CB_SEND_ACK]:
err = nl_cb_call(cb, NL_CB_SEND_ACK, msg) # NL_CB_CALL(cb, NL_CB_SEND_ACK, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
if hdr.nlmsg_type == NLMSG_DONE:
# Messages terminates a multipart message, this is usually the end of a message and therefore we slip
# out of the loop by default. the user may overrule this action by skipping this packet.
multipart = 0
if cb.cb_set[NL_CB_FINISH]:
err = nl_cb_call(cb, NL_CB_FINISH, msg) # NL_CB_CALL(cb, NL_CB_FINISH, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
elif hdr.nlmsg_type == NLMSG_NOOP:
# Message to be ignored, the default action is to skip this message if no callback is specified. The
# user may overrule this action by returning NL_PROCEED.
if cb.cb_set[NL_CB_SKIPPED]:
err = nl_cb_call(cb, NL_CB_SKIPPED, msg) # NL_CB_CALL(cb, NL_CB_SKIPPED, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
else:
hdr = nlmsg_next(hdr, n)
continue
elif hdr.nlmsg_type == NLMSG_OVERRUN:
# Data got lost, report back to user. The default action is to quit parsing. The user may overrule this
# action by retuning NL_SKIP or NL_PROCEED (dangerous).
if cb.cb_set[NL_CB_OVERRUN]:
err = nl_cb_call(cb, NL_CB_OVERRUN, msg) # NL_CB_CALL(cb, NL_CB_OVERRUN, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
else:
return -NLE_DUMP_INTR if interrupted else -NLE_MSG_OVERFLOW
elif hdr.nlmsg_type == NLMSG_ERROR:
# Message carries a nlmsgerr.
e = nlmsgerr(nlmsg_data(hdr))
if hdr.nlmsg_len < nlmsg_size(e.SIZEOF):
# Truncated error message, the default action is to stop parsing. The user may overrule this action
# by returning NL_SKIP or NL_PROCEED (dangerous).
if cb.cb_set[NL_CB_INVALID]:
err = nl_cb_call(cb, NL_CB_INVALID, msg) # NL_CB_CALL(cb, NL_CB_INVALID, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
else:
return -NLE_DUMP_INTR if interrupted else -NLE_MSG_TRUNC
elif e.error:
# Error message reported back from kernel.
if cb.cb_err:
err = cb.cb_err(nla, e, cb.cb_err_arg)
if err < 0:
return -NLE_DUMP_INTR if interrupted else err
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else -nl_syserr2nlerr(e.error)
else:
return -NLE_DUMP_INTR if interrupted else -nl_syserr2nlerr(e.error)
elif cb.cb_set[NL_CB_ACK]:
err = nl_cb_call(cb, NL_CB_ACK, msg) # NL_CB_CALL(cb, NL_CB_ACK, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
else:
# Valid message (not checking for MULTIPART bit to get along with broken kernels. NL_SKIP has no effect
# on this.
if cb.cb_set[NL_CB_VALID]:
err = nl_cb_call(cb, NL_CB_VALID, msg) # NL_CB_CALL(cb, NL_CB_VALID, msg)
if err == NL_OK:
pass
elif err == NL_SKIP:
hdr = nlmsg_next(hdr, n)
continue
elif err == NL_STOP:
return -NLE_DUMP_INTR if interrupted else nrecv
else:
return -NLE_DUMP_INTR if interrupted else (err or nrecv)
hdr = nlmsg_next(hdr, n)
del buf[:]
creds = None
if multipart:
# Multipart message not yet complete, continue reading.
continue
err = 0
if interrupted:
return -NLE_DUMP_INTR
if not err:
err = nrecv
return err
def nl_recv(sk, nla, buf, creds=None):
"""Receive data from Netlink socket.
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/nl.c#L625
Receives data from a connected netlink socket using recvmsg() and returns the number of bytes read. The read data is
stored in a newly allocated buffer that is assigned to `buf`. The peer's netlink address will be stored in `nla`.
This function blocks until data is available to be read unless the socket has been put into non-blocking mode using
nl_socket_set_nonblocking() in which case this function will return immediately with a return value of 0.
The buffer size used when reading from the netlink socket and thus limiting the maximum size of a netlink message
that can be read defaults to the size of a memory page (getpagesize()). The buffer size can be modified on a per
socket level using the function `nl_socket_set_msg_buf_size()`.
If message peeking is enabled using nl_socket_enable_msg_peek() the size of the message to be read will be
determined using the MSG_PEEK flag prior to performing the actual read. This leads to an additional recvmsg() call
for every read operation which has performance implications and is not recommended for high throughput protocols.
An eventual interruption of the recvmsg() system call is automatically handled by retrying the operation.
If receiving of credentials has been enabled using the function `nl_socket_set_passcred()`, this function will
allocate a new struct `ucred` filled with the received credentials and assign it to `creds`.
Positional arguments:
sk -- Netlink socket (nl_sock class instance) (input).
nla -- Netlink socket structure to hold address of peer (sockaddr_nl class instance) (output).
buf -- destination bytearray() for message content (output).
creds -- destination class instance for credentials (ucred class instance) (output).
Returns:
Two-item tuple. First item is number of bytes read, 0 on EOF, 0 on no data event (non-blocking mode), or a negative
error code. Second item is the message content from the socket or None.
"""
flags = 0
page_size = resource.getpagesize() * 4
if sk.s_flags & NL_MSG_PEEK:
flags |= socket.MSG_PEEK | socket.MSG_TRUNC
iov_len = sk.s_bufsize or page_size
if creds and sk.s_flags & NL_SOCK_PASSCRED:
raise NotImplementedError # TODO https://github.com/Robpol86/libnl/issues/2
while True: # This is the `goto retry` implementation.
try:
if hasattr(sk.socket_instance, 'recvmsg'):
iov, _, msg_flags, address = sk.socket_instance.recvmsg(iov_len, 0, flags)
else:
iov, address = sk.socket_instance.recvfrom(iov_len, flags)
msg_flags = 0
except OSError as exc:
if exc.errno == errno.EINTR:
continue # recvmsg() returned EINTR, retrying.
return -nl_syserr2nlerr(exc.errno)
nla.nl_family = sk.socket_instance.family # recvmsg() in C does this, but not Python's.
if not iov:
return 0
if msg_flags & socket.MSG_CTRUNC:
raise NotImplementedError # TODO https://github.com/Robpol86/libnl/issues/2
if iov_len < len(iov) or msg_flags & socket.MSG_TRUNC:
# Provided buffer is not long enough.
# Enlarge it to size of n (which should be total length of the message) and try again.
iov_len = len(iov)
continue
if flags:
# Buffer is big enough, do the actual reading.
flags = 0
continue
nla.nl_pid = address[0]
nla.nl_groups = address[1]
if creds and sk.s_flags * NL_SOCK_PASSCRED:
raise NotImplementedError # TODO https://github.com/Robpol86/libnl/issues/2
if iov:
buf += iov
return len(buf)
def nl_error_handler_verbose(_, err, arg):
"""https://github.com/thom311/libnl/blob/libnl3_2_25/lib/handlers.c#L78."""
ofd = arg or _LOGGER.debug
ofd('-- Error received: ' + strerror(-err.error))
ofd('-- Original message: ' + print_header_content(err.msg))
return -nl_syserr2nlerr(err.error)