monitor_fdpass.c revision 1.2 
1/*	$OpenBSD: monitor_fdpass.c,v 1.2 2008/03/13 01:49:52 deraadt 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
30void
31send_fd(int sock, int fd)
32{
33	struct msghdr msg;
34	union {
35		struct cmsghdr hdr;
36		char buf[CMSG_SPACE(sizeof(int))];
37	} cmsgbuf;
38	struct cmsghdr *cmsg;
39	struct iovec vec;
40	int result = 0;
41	ssize_t n;
42
43	memset(&msg, 0, sizeof(msg));
44
45	if (fd >= 0) {
46		msg.msg_control = (caddr_t)&cmsgbuf.buf;
47		msg.msg_controllen = sizeof(cmsgbuf.buf);
48		cmsg = CMSG_FIRSTHDR(&msg);
49		cmsg->cmsg_len = CMSG_LEN(sizeof(int));
50		cmsg->cmsg_level = SOL_SOCKET;
51		cmsg->cmsg_type = SCM_RIGHTS;
52		*(int *)CMSG_DATA(cmsg) = fd;
53	} else
54		result = errno;
55
56	vec.iov_base = &result;
57	vec.iov_len = sizeof(int);
58	msg.msg_iov = &vec;
59	msg.msg_iovlen = 1;
60
61	if ((n = sendmsg(sock, &msg, 0)) == -1)
62		syslog(LOG_WARNING, "send_fd: sendmsg(%d): %m", sock);
63	if (n != sizeof(int))
64		syslog(LOG_WARNING, "send_fd: sendmsg: expected sent 1 got %ld",
65		    (long)n);
66}
67
68int
69recv_fd(int sock)
70{
71	struct msghdr msg;
72	union {
73		struct cmsghdr hdr;
74		char buf[CMSG_SPACE(sizeof(int))];
75	} cmsgbuf;
76	struct cmsghdr *cmsg;
77	struct iovec vec;
78	ssize_t n;
79	int result;
80	int fd;
81
82	memset(&msg, 0, sizeof(msg));
83	vec.iov_base = &result;
84	vec.iov_len = sizeof(int);
85	msg.msg_iov = &vec;
86	msg.msg_iovlen = 1;
87	msg.msg_control = &cmsgbuf.buf;
88	msg.msg_controllen = sizeof(cmsgbuf.buf);
89
90	if ((n = recvmsg(sock, &msg, 0)) == -1)
91		syslog(LOG_WARNING, "recv_fd: recvmsg(%d): %m", sock);
92	if (n != sizeof(int))
93		syslog(LOG_WARNING,
94		    "recv_fd: recvmsg: expected received 1 got %ld", (long)n);
95	if (result == 0) {
96		cmsg = CMSG_FIRSTHDR(&msg);
97		if (cmsg == NULL) {
98			syslog(LOG_WARNING, "recv_fd: no message header");
99			return (-1);
100		}
101		if (cmsg->cmsg_type != SCM_RIGHTS)
102			syslog(LOG_WARNING, "recv_fd: expected type %d got %d",
103			    SCM_RIGHTS, cmsg->cmsg_type);
104		fd = (*(int *)CMSG_DATA(cmsg));
105		return (fd);
106	} else {
107		errno = result;
108		return (-1);
109	}
110}
111