1 /*-
2  * Copyright (c) 2012 The FreeBSD Foundation
3  * All rights reserved.
4  *
5  * This software was developed by Pawel Jakub Dawidek under sponsorship from
6  * the FreeBSD Foundation.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/types.h>
31 #include <sys/select.h>
32 #include <sys/socket.h>
33 
34 #include <assert.h>
35 #include <errno.h>
36 #include <stdlib.h>
37 #include <strings.h>
38 
39 #include "misc.h"
40 
41 int
42 pdwait(int pfd)
43 {
44 	fd_set fdset;
45 
46 	FD_ZERO(&fdset);
47 	FD_SET(pfd, &fdset);
48 
49 	return (select(pfd + 1, NULL, &fdset, NULL, NULL) == -1 ? -1 : 0);
50 }
51 
52 int
53 descriptor_send(int sock, int fd)
54 {
55 	unsigned char ctrl[CMSG_SPACE(sizeof(fd))];
56 	struct msghdr msg;
57 	struct cmsghdr *cmsg;
58 
59 	assert(sock >= 0);
60 	assert(fd >= 0);
61 
62 	bzero(&msg, sizeof(msg));
63 	bzero(&ctrl, sizeof(ctrl));
64 
65 	msg.msg_iov = NULL;
66 	msg.msg_iovlen = 0;
67 	msg.msg_control = ctrl;
68 	msg.msg_controllen = sizeof(ctrl);
69 
70 	cmsg = CMSG_FIRSTHDR(&msg);
71 	cmsg->cmsg_level = SOL_SOCKET;
72 	cmsg->cmsg_type = SCM_RIGHTS;
73 	cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
74 	bcopy(&fd, CMSG_DATA(cmsg), sizeof(fd));
75 
76 	if (sendmsg(sock, &msg, 0) == -1)
77 		return (errno);
78 
79 	return (0);
80 }
81 
82 int
83 descriptor_recv(int sock, int *fdp)
84 {
85 	unsigned char ctrl[CMSG_SPACE(sizeof(*fdp))];
86 	struct msghdr msg;
87 	struct cmsghdr *cmsg;
88 	struct iovec iov;
89 	int val;
90 
91 	assert(sock >= 0);
92 	assert(fdp != NULL);
93 
94 	bzero(&msg, sizeof(msg));
95 	bzero(&ctrl, sizeof(ctrl));
96 
97 #if 1
98 	/*
99 	 * This doesn't really make sense, as we don't plan to receive any
100 	 * data, but if no buffer is provided and recv(2) returns 0 without
101 	 * control message. Must be kernel bug.
102 	 */
103 	iov.iov_base = &val;
104 	iov.iov_len = sizeof(val);
105 	msg.msg_iov = &iov;
106 	msg.msg_iovlen = 1;
107 #else
108 	msg.msg_iov = NULL;
109 	msg.msg_iovlen = 0;
110 #endif
111 	msg.msg_control = ctrl;
112 	msg.msg_controllen = sizeof(ctrl);
113 
114 	if (recvmsg(sock, &msg, 0) == -1)
115 		return (errno);
116 
117 	cmsg = CMSG_FIRSTHDR(&msg);
118 	if (cmsg == NULL || cmsg->cmsg_level != SOL_SOCKET ||
119 	    cmsg->cmsg_type != SCM_RIGHTS) {
120 		return (EINVAL);
121 	}
122 	bcopy(CMSG_DATA(cmsg), fdp, sizeof(*fdp));
123 
124 	return (0);
125 }
126