1/* SCTP kernel Implementation: User API extensions.
2 *
3 * sctp_recvmsg.c
4 *
5 * Distributed under the terms of the LGPL v2.1 as described in
6 *    http://www.gnu.org/copyleft/lesser.txt
7 *
8 * This file is part of the user library that offers support for the
9 * SCTP kernel Implementation. The main purpose of this
10 * code is to provide the SCTP Socket API mappings for user
11 * application to interface with the SCTP in kernel.
12 *
13 * This implementation is based on the Socket API Extensions for SCTP
14 * defined in <draft-ietf-tsvwg-sctpsocket-10.txt>
15 *
16 * Copyright (c) 2003 International Business Machines, Corp.
17 *
18 * Written or modified by:
19 *  Ryan Layer	<rmlayer@us.ibm.com>
20 *
21 * An implementation may provide a library function (or possibly system
22 * call) to assist the user with the advanced features of SCTP. Note
23 * that in order for the sctp_sndrcvinfo structure to be filled in by
24 * sctp_recvmsg() the caller must enable the sctp_data_io_events with
25 * the SCTP_EVENTS option.
26 *
27 * sctp_recvmsg(). Its syntax is,
28 *
29 * int sctp_recvmsg(int s,
30 *		    void *msg,
31 *		    size_t len,
32 *		    struct sockaddr *from,
33 *		    socklen_t *fromlen,
34 *		    struct sctp_sndrcvinfo *sinfo,
35 *		    int *msg_flags)
36 *
37 *
38 * s          - is the socket descriptor
39 * msg        - is a message buffer to be filled.
40 * len        - is the length of the message buffer.
41 * from       - is a pointer to a address to be filled with
42 *		the sender of this messages address.
43 * fromlen    - is the from length.
44 * sinfo      - A pointer to a sctp_sndrcvinfo structure
45 *		to be filled upon receipt of the message.
46 * msg_flags  - A pointer to a integer to be filled with
47 *		any message flags (e.g. MSG_NOTIFICATION).
48 */
49
50#include <string.h>
51#include <errno.h>
52#include <sys/socket.h>   /* struct sockaddr_storage, setsockopt() */
53#include <netinet/sctp.h>
54
55int sctp_recvmsg(int s, void *msg, size_t len, struct sockaddr *from,
56		 socklen_t *fromlen, struct sctp_sndrcvinfo *sinfo,
57		 int *msg_flags)
58{
59	int error;
60	struct iovec iov;
61	struct msghdr inmsg;
62	char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
63	struct cmsghdr *cmsg = NULL;
64
65	memset(&inmsg, 0, sizeof (inmsg));
66
67	iov.iov_base = msg;
68	iov.iov_len = len;
69
70	inmsg.msg_name = from;
71	inmsg.msg_namelen = fromlen ? *fromlen : 0;
72	inmsg.msg_iov = &iov;
73	inmsg.msg_iovlen = 1;
74	inmsg.msg_control = incmsg;
75	inmsg.msg_controllen = sizeof(incmsg);
76
77	error = recvmsg(s, &inmsg, msg_flags ? *msg_flags : 0);
78	if (error < 0)
79		return error;
80
81	if (fromlen)
82		*fromlen = inmsg.msg_namelen;
83	if (msg_flags)
84		*msg_flags = inmsg.msg_flags;
85
86	if (!sinfo)
87		return error;
88
89	for (cmsg = CMSG_FIRSTHDR(&inmsg); cmsg != NULL;
90				 cmsg = CMSG_NXTHDR(&inmsg, cmsg)){
91		if ((IPPROTO_SCTP == cmsg->cmsg_level) &&
92		    (SCTP_SNDRCV == cmsg->cmsg_type))
93			break;
94	}
95
96        /* Copy sinfo. */
97	if (cmsg)
98		memcpy(sinfo, CMSG_DATA(cmsg), sizeof(struct sctp_sndrcvinfo));
99
100	return (error);
101}
102