sendmsg.c

SCTP 协议实现源代码

/* SCTP kernel Implementation: User API extensions.
 *
 * sendmsg.c
 *
 * Distributed under the terms of the LGPL v2.1 as described in
 *    http://www.gnu.org/copyleft/lesser.txt 
 *
 * This file is part of the user library that offers support for the
 * SCTP kernel Implementation. The main purpose of this
 * code is to provide the SCTP Socket API mappings for user
 * application to interface with the SCTP in kernel.
 *
 * This implementation is based on the Socket API Extensions for SCTP
 * defined in <draft-ietf-tsvwg-sctpsocket-10.txt>
 *
 * Copyright (c) 2003 Intel Corp.
 *
 * Written or modified by:
 *  Ardelle Fan     <[e-mail]>
 */

#include <string.h>
#include <sys/socket.h>   /* struct sockaddr_storage, setsockopt() */
#include <netinet/sctp.h>

/* This library function assists the user with the advanced features
 * of SCTP.  This is a new SCTP API described in the section 8.7 of the
 * Sockets API Extensions for SCTP. This is implemented using the
 * sendmsg() interface.
 */
int
sctp_sendmsg(int s, const void *msg, size_t len, struct sockaddr *to,
	     socklen_t tolen, uint32_t ppid, uint32_t flags,
	     uint16_t stream_no, uint32_t timetolive, uint32_t context)
{
	struct msghdr outmsg;
	struct iovec iov;
	char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
	struct cmsghdr *cmsg;
	struct sctp_sndrcvinfo *sinfo;

	outmsg.msg_name = to;
	outmsg.msg_namelen = tolen;
	outmsg.msg_iov = &iov;
	iov.iov_base = (void *)msg;
	iov.iov_len = len;
	outmsg.msg_iovlen = 1;

	outmsg.msg_control = outcmsg;
	outmsg.msg_controllen = sizeof(outcmsg);
	outmsg.msg_flags = 0;

	cmsg = CMSG_FIRSTHDR(&outmsg);
	cmsg->cmsg_level = IPPROTO_SCTP;
	cmsg->cmsg_type = SCTP_SNDRCV;
	cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));

	outmsg.msg_controllen = cmsg->cmsg_len;
	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
	memset(sinfo, 0, sizeof(struct sctp_sndrcvinfo));
	sinfo->sinfo_ppid = ppid;
	sinfo->sinfo_flags = flags;
	sinfo->sinfo_stream = stream_no;
	sinfo->sinfo_timetolive = timetolive;
	sinfo->sinfo_context = context;

	return sendmsg(s, &outmsg, 0);
}

/* This library function assist the user with sending a message without
 * dealing directly with the CMSG header.
 */
int
sctp_send(int s, const void *msg, size_t len,
          const struct sctp_sndrcvinfo *sinfo, int flags)
{
	struct msghdr outmsg;
	struct iovec iov;

	outmsg.msg_name = NULL;
	outmsg.msg_namelen = 0;
	outmsg.msg_iov = &iov;
	iov.iov_base = (void *)msg;
	iov.iov_len = len;
	outmsg.msg_iovlen = 1;
	outmsg.msg_controllen = 0;

	if (sinfo) {	
		char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
		struct cmsghdr *cmsg;

		outmsg.msg_control = outcmsg;
		outmsg.msg_controllen = sizeof(outcmsg);
		outmsg.msg_flags = 0;

		cmsg = CMSG_FIRSTHDR(&outmsg);
		cmsg->cmsg_level = IPPROTO_SCTP;
		cmsg->cmsg_type = SCTP_SNDRCV;
		cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));

		outmsg.msg_controllen = cmsg->cmsg_len;
		memcpy(CMSG_DATA(cmsg), sinfo, sizeof(struct sctp_sndrcvinfo));
	}

	return sendmsg(s, &outmsg, flags);
}