void NLSocket::process_receive(std::size_t bytes_xferred,
unsigned int seq, unsigned int portid)
{
const struct nlmsghdr *nlh = (const struct nlmsghdr *)recv_buffer_.data();
for (;NLMSG_OK(nlh, bytes_xferred); nlh = NLMSG_NEXT(nlh, bytes_xferred)) {
// Should be 0 for messages from the kernel.
if (nlh->nlmsg_pid && portid && nlh->nlmsg_pid != portid)
continue;
if (seq && nlh->nlmsg_seq != seq)
continue;
if (nlh->nlmsg_type >= NLMSG_MIN_TYPE) {
process_nlmsg(nlh);
} else {
switch (nlh->nlmsg_type) {
case NLMSG_ERROR: {
fmt::print(stderr, "nlsocket: Received a NLMSG_ERROR: {}\n",
strerror(nlmsg_get_error(nlh)));
auto nle = reinterpret_cast<struct nlmsgerr *>(NLMSG_DATA(nlh));
fmt::print(stderr, "error={} len={} type={} flags={} seq={} pid={}\n",
nle->error, nle->msg.nlmsg_len, nle->msg.nlmsg_type,
nle->msg.nlmsg_flags, nle->msg.nlmsg_seq,
nle->msg.nlmsg_pid);
break;
}
case NLMSG_OVERRUN:
fmt::print(stderr, "nlsocket: Received a NLMSG_OVERRUN.\n");
case NLMSG_NOOP:
case NLMSG_DONE:
default:
break;
}
}
}
}
static int process_response(int wait_for_done, unsigned seq) {
assert(fd >= 0);
do {
size_t bytes;
ssize_t r;
char replybuf[8*1024];
char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
struct msghdr msghdr;
struct cmsghdr *cmsghdr;
struct ucred *ucred;
struct iovec iov;
struct nlmsghdr *p = (struct nlmsghdr *) replybuf;
memset(&iov, 0, sizeof(iov));
iov.iov_base = replybuf;
iov.iov_len = sizeof(replybuf);
memset(&msghdr, 0, sizeof(msghdr));
msghdr.msg_name = (void*) NULL;
msghdr.msg_namelen = 0;
msghdr.msg_iov = &iov;
msghdr.msg_iovlen = 1;
msghdr.msg_control = cred_msg;
msghdr.msg_controllen = sizeof(cred_msg);
msghdr.msg_flags = 0;
if ((r = recvmsg(fd, &msghdr, 0)) < 0) {
daemon_log(LOG_ERR, "recvmsg() failed: %s", strerror(errno));
return -1;
}
if (!(cmsghdr = CMSG_FIRSTHDR(&msghdr)) || cmsghdr->cmsg_type != SCM_CREDENTIALS) {
daemon_log(LOG_WARNING, "No sender credentials received, ignoring data.");
return -1;
}
ucred = (struct ucred*) CMSG_DATA(cmsghdr);
if (ucred->uid != 0)
return -1;
bytes = (size_t) r;
for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
if (!NLMSG_OK(p, bytes) || bytes < sizeof(struct nlmsghdr) || bytes < p->nlmsg_len) {
daemon_log(LOG_ERR, "Netlink packet too small.");
return -1;
}
if (p->nlmsg_type == NLMSG_DONE && wait_for_done && p->nlmsg_seq == seq && (pid_t) p->nlmsg_pid == getpid())
return 0;
if (p->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *e = (struct nlmsgerr *) NLMSG_DATA (p);
if (e->error) {
daemon_log(LOG_ERR, "Netlink error: %s", strerror(-e->error));
return -1;
}
}
if (process_nlmsg(p) < 0)
return -1;
}
} while (wait_for_done);
return 0;
}
