1/*	$OpenBSD: monitor_fdpass.c,v 1.17 2016/02/29 20:22:36 jca Exp $	*/
2
3/*
4 * Copyright 2001 Niels Provos <provos@citi.umich.edu>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include <sys/types.h>
29#include <sys/socket.h>
30#include <sys/uio.h>
31
32#include <errno.h>
33#include <string.h>
34
35#include "log.h"
36#include "monitor.h"
37
38int
39mm_send_fd(int socket, int fd)
40{
41	struct msghdr   msg;
42	union {
43		struct cmsghdr hdr;
44		char buf[CMSG_SPACE(sizeof(int))];
45	} cmsgbuf;
46	char		ch = '\0';
47	struct cmsghdr *cmsg;
48	struct iovec    vec;
49	ssize_t         n;
50
51	bzero(&msg, sizeof msg);
52	msg.msg_control = (caddr_t)&cmsgbuf.buf;
53	msg.msg_controllen = sizeof(cmsgbuf.buf);
54	cmsg = CMSG_FIRSTHDR(&msg);
55	cmsg->cmsg_len = CMSG_LEN(sizeof(int));
56	cmsg->cmsg_level = SOL_SOCKET;
57	cmsg->cmsg_type = SCM_RIGHTS;
58	*(int *)CMSG_DATA(cmsg) = fd;
59
60	vec.iov_base = &ch;
61	vec.iov_len = 1;
62	msg.msg_iov = &vec;
63	msg.msg_iovlen = 1;
64
65	if ((n = sendmsg(socket, &msg, 0)) == -1) {
66		log_error("mm_send_fd: sendmsg(%d)", fd);
67		return -1;
68	}
69	if (n != 1) {
70		log_error("mm_send_fd: sendmsg: expected sent 1 got %zd", n);
71		return -1;
72	}
73	return 0;
74}
75
76int
77mm_receive_fd(int socket)
78{
79	struct msghdr   msg;
80	union {
81		struct cmsghdr hdr;
82		char buf[CMSG_SPACE(sizeof(int))];
83	} cmsgbuf;
84	char		ch;
85	struct cmsghdr *cmsg;
86	struct iovec    vec;
87	ssize_t         n;
88	int             fd;
89
90	bzero(&msg, sizeof msg);
91	vec.iov_base = &ch;
92	vec.iov_len = 1;
93	msg.msg_iov = &vec;
94	msg.msg_iovlen = 1;
95	msg.msg_control = &cmsgbuf.buf;
96	msg.msg_controllen = sizeof(cmsgbuf.buf);
97
98	if ((n = recvmsg(socket, &msg, 0)) == -1) {
99		log_error("mm_receive_fd: recvmsg");
100		return -1;
101	}
102	if (n != 1) {
103		log_error("mm_receive_fd: recvmsg: expected received 1 got %zd",
104		    n);
105		return -1;
106	}
107	cmsg = CMSG_FIRSTHDR(&msg);
108	if (cmsg == NULL) {
109		log_error("mm_receive_fd: no message header");
110		return -1;
111	}
112	if (cmsg->cmsg_type != SCM_RIGHTS) {
113		log_error("mm_receive_fd: expected type %d got %d", SCM_RIGHTS,
114		    cmsg->cmsg_type);
115		return -1;
116	}
117	fd = (*(int *)CMSG_DATA(cmsg));
118	return fd;
119}
120