/*
* Send a command (char), data (head), and a file descriptor (sd_send) to a local process
* over unix socket sd. Unfortunately, there's no portable way to send file descriptors
* to other processes, so this code, as well as its analog (control_message_from_parent below),
* is Linux-specific. This function runs in the context of the main process and is used to
* send commands, data, and file descriptors to the background process.
*/
static void
port_share_sendmsg (const socket_descriptor_t sd,
const char command,
const struct buffer *head,
const socket_descriptor_t sd_send)
{
if (socket_defined (sd))
{
struct msghdr mesg;
struct cmsghdr* h;
struct iovec iov[2];
socket_descriptor_t sd_null[2] = { SOCKET_UNDEFINED, SOCKET_UNDEFINED };
char cmd;
ssize_t status;
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: sendmsg sd=%d len=%d",
(int)sd_send,
head ? BLEN(head) : -1);
CLEAR (mesg);
cmd = command;
iov[0].iov_base = &cmd;
iov[0].iov_len = sizeof (cmd);
mesg.msg_iovlen = 1;
if (head)
{
iov[1].iov_base = BPTR (head);
iov[1].iov_len = BLEN (head);
mesg.msg_iovlen = 2;
}
mesg.msg_iov = iov;
mesg.msg_controllen = cmsg_size ();
mesg.msg_control = (char *) malloc (mesg.msg_controllen);
check_malloc_return (mesg.msg_control);
mesg.msg_flags = 0;
h = CMSG_FIRSTHDR(&mesg);
h->cmsg_level = SOL_SOCKET;
h->cmsg_type = SCM_RIGHTS;
h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));
if (socket_defined (sd_send))
{
*((socket_descriptor_t*)CMSG_DATA(h)) = sd_send;
}
else
{
socketpair (PF_UNIX, SOCK_DGRAM, 0, sd_null);
*((socket_descriptor_t*)CMSG_DATA(h)) = sd_null[0];
}
status = sendmsg (sd, &mesg, MSG_NOSIGNAL);
if (status == -1)
msg (M_WARN, "PORT SHARE: sendmsg failed (unable to communicate with background process)");
close_socket_if_defined (sd_null[0]);
close_socket_if_defined (sd_null[1]);
free (mesg.msg_control);
}
}
static inline void
close_socket_if_defined (const socket_descriptor_t sd)
{
if (socket_defined (sd))
openvpn_close_socket (sd);
}
