1/*	$OpenBSD: monitor_fdpass.c,v 1.7 2016/02/29 20:22:36 jca Exp $	*/
2
3/*
4 * Copyright (c) 2002 Matthieu Herrb
5 * Copyright (c) 2001 Niels Provos <provos@citi.umich.edu>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
16 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
17 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20#include <sys/types.h>
21#include <sys/socket.h>
22#include <sys/uio.h>
23
24#include <errno.h>
25#include <fcntl.h>
26#include <string.h>
27#include <syslog.h>
28#include <unistd.h>
29#include "monitor.h"
30
31void
32send_fd(int sock, int fd)
33{
34	struct msghdr msg;
35	union {
36		struct cmsghdr hdr;
37		char buf[CMSG_SPACE(sizeof(int))];
38	} cmsgbuf;
39	struct cmsghdr *cmsg;
40	struct iovec vec;
41	int result = 0;
42	ssize_t n;
43
44	memset(&msg, 0, sizeof(msg));
45
46	if (fd >= 0) {
47		msg.msg_control = (caddr_t)&cmsgbuf.buf;
48		msg.msg_controllen = sizeof(cmsgbuf.buf);
49		cmsg = CMSG_FIRSTHDR(&msg);
50		cmsg->cmsg_len = CMSG_LEN(sizeof(int));
51		cmsg->cmsg_level = SOL_SOCKET;
52		cmsg->cmsg_type = SCM_RIGHTS;
53		*(int *)CMSG_DATA(cmsg) = fd;
54	} else
55		result = errno;
56
57	vec.iov_base = &result;
58	vec.iov_len = sizeof(int);
59	msg.msg_iov = &vec;
60	msg.msg_iovlen = 1;
61
62	if ((n = sendmsg(sock, &msg, 0)) == -1)
63		syslog(LOG_WARNING, "send_fd: sendmsg(%d): %m", sock);
64	if (n != sizeof(int))
65		syslog(LOG_WARNING, "send_fd: sendmsg: expected sent 1 got %zd",
66		    n);
67}
68
69int
70recv_fd(int sock)
71{
72	struct msghdr msg;
73	union {
74		struct cmsghdr hdr;
75		char buf[CMSG_SPACE(sizeof(int))];
76	} cmsgbuf;
77	struct cmsghdr *cmsg;
78	struct iovec vec;
79	ssize_t n;
80	int result;
81	int fd;
82
83	memset(&msg, 0, sizeof(msg));
84	vec.iov_base = &result;
85	vec.iov_len = sizeof(int);
86	msg.msg_iov = &vec;
87	msg.msg_iovlen = 1;
88	msg.msg_control = &cmsgbuf.buf;
89	msg.msg_controllen = sizeof(cmsgbuf.buf);
90
91	if ((n = recvmsg(sock, &msg, 0)) == -1) {
92		syslog(LOG_WARNING, "recv_fd: recvmsg(%d): %m", sock);
93		return -1;
94	}
95	if (n != sizeof(int))
96		syslog(LOG_WARNING,
97		    "recv_fd: recvmsg: expected received 1 got %zd", n);
98	if (result == 0) {
99		cmsg = CMSG_FIRSTHDR(&msg);
100		if (cmsg == NULL) {
101			syslog(LOG_WARNING, "recv_fd: no message header");
102			return (-1);
103		}
104		if (cmsg->cmsg_type != SCM_RIGHTS)
105			syslog(LOG_WARNING, "recv_fd: expected type %d got %d",
106			    SCM_RIGHTS, cmsg->cmsg_type);
107		fd = (*(int *)CMSG_DATA(cmsg));
108		return (fd);
109	} else {
110		errno = result;
111		return (-1);
112	}
113}
114