def __init__(self):
"""Constructor."""
self.nm_protocol = 0
self.nm_flags = 0
self.nm_src = sockaddr_nl()
self.nm_dst = sockaddr_nl()
self.nm_creds = None
self.nm_nlh = None
self.nm_size = 0
self.nm_refcnt = 1
def __init__(self):
"""Constructor."""
self.s_local = sockaddr_nl()
self.s_peer = sockaddr_nl()
self.s_proto = 0
self.s_seq_next = 0
self.s_seq_expect = 0
self.s_flags = 0
self.s_cb = None
self.s_bufsize = None
self.socket_instance = None
def test_nl_recv():
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_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;
};
int main() {
// Send data to the kernel.
struct nl_sock *sk = nl_socket_alloc();
sk->s_seq_next = 0;
nl_connect(sk, NETLINK_ROUTE);
int ret = nl_send_simple(sk, 0, NLM_F_REQUEST, NULL, 0);
printf("Bytes Sent: %d\n", ret);
// Retrieve kernel's response.
// nl_recvmsgs_default(sk);
// return 0;
unsigned char *buf = NULL;
struct sockaddr_nl nla = {0};
printf("%d == nla.nl_family\n", nla.nl_family);
int n = nl_recv(sk, &nla, &buf, NULL);
printf("Bytes Recv: %d\n", n);
int i = 0; for (i = 0; i<n; i++) printf("%02x", buf[i]); printf("\n");
printf("%d == nla.nl_family\n", nla.nl_family);
return 0;
}
// Expected output:
// Bytes Sent: 16
// 0 == nla.nl_family
// Bytes Recv: 36
// 240000000200000000000000844c000000000000100000000000050000000000844c0000
// 16 == nla.nl_family
// Output delta:
// 240000000200000000000000ac4e000000000000100000000000050000000000ac4e0000
"""
sk = nl_socket_alloc()
sk.s_seq_next = 0
nl_connect(sk, NETLINK_ROUTE)
assert 16 == nl_send_simple(sk, 0, NLM_F_REQUEST, None)
buf = bytearray()
nla = sockaddr_nl()
assert 0 == nla.nl_family
assert 36 == nl_recv(sk, nla, buf, None)
nl_socket_free(sk)
buf_hex = binascii.hexlify(buffer(buf)).decode('ascii')
assert re.match(
r'240000000200000000000000....000000000000100000000000050000000000....0000',
buf_hex)
assert 16 == nla.nl_family
def test_nl_recv():
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_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;
};
int main() {
// Send data to the kernel.
struct nl_sock *sk = nl_socket_alloc();
sk->s_seq_next = 0;
nl_connect(sk, NETLINK_ROUTE);
int ret = nl_send_simple(sk, 0, NLM_F_REQUEST, NULL, 0);
printf("Bytes Sent: %d\n", ret);
// Retrieve kernel's response.
// nl_recvmsgs_default(sk);
// return 0;
unsigned char *buf = NULL;
struct sockaddr_nl nla = {0};
printf("%d == nla.nl_family\n", nla.nl_family);
int n = nl_recv(sk, &nla, &buf, NULL);
printf("Bytes Recv: %d\n", n);
int i = 0; for (i = 0; i<n; i++) printf("%02x", buf[i]); printf("\n");
printf("%d == nla.nl_family\n", nla.nl_family);
return 0;
}
// Expected output:
// Bytes Sent: 16
// 0 == nla.nl_family
// Bytes Recv: 36
// 240000000200000000000000844c000000000000100000000000050000000000844c0000
// 16 == nla.nl_family
// Output delta:
// 240000000200000000000000ac4e000000000000100000000000050000000000ac4e0000
"""
sk = nl_socket_alloc()
sk.s_seq_next = 0
nl_connect(sk, NETLINK_ROUTE)
assert 16 == nl_send_simple(sk, 0, NLM_F_REQUEST, None)
buf = bytearray()
nla = sockaddr_nl()
assert 0 == nla.nl_family
assert 36 == nl_recv(sk, nla, buf, None)
nl_socket_free(sk)
buf_hex = binascii.hexlify(buffer(buf)).decode('ascii')
assert re.match(r'240000000200000000000000....000000000000100000000000050000000000....0000', buf_hex)
assert 16 == nla.nl_family
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 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
