dsr-ack.c

LINUX下的mesh路由协议dsr的源代码包

/* Copyright (C) Uppsala University
 *
 * This file is distributed under the terms of the GNU general Public
 * License (GPL), see the file LICENSE
 *
 * Author: Erik Nordström, <[e-mail]>
 */
#ifdef __KERNEL__
#include <linux/proc_fs.h>
#include "dsr-dev.h"
#endif

#ifdef NS2
#include "ns-agent.h"
#endif

#include "tbl.h"
#include "debug.h"
#include "dsr-opt.h"
#include "dsr-ack.h"
#include "link-cache.h"
#include "neigh.h"
#include "maint-buf.h"

struct dsr_ack_opt *dsr_ack_opt_add(char *buf, int len, struct in_addr src,
				    struct in_addr dst, unsigned short id)
{
	struct dsr_ack_opt *ack = (struct dsr_ack_opt *)buf;

	if (len < (int)DSR_ACK_HDR_LEN)
		return NULL;

	ack->type = DSR_OPT_ACK;
	ack->length = DSR_ACK_OPT_LEN;
	ack->id = htons(id);
	ack->dst = dst.s_addr;
	ack->src = src.s_addr;

	return ack;
}

int NSCLASS dsr_ack_send(struct in_addr dst, unsigned short id)
{
	struct dsr_pkt *dp;
	struct dsr_ack_opt *ack_opt;
	int len;
	char *buf;

	/* srt = dsr_rtc_find(my_addr(), dst); */

/* 	if (!srt) { */
/* 		DEBUG("No source route to %s\n", print_ip(dst.s_addr)); */
/* 		return -1; */
/* 	} */

	len = DSR_OPT_HDR_LEN + /* DSR_SRT_OPT_LEN(srt) +  */ DSR_ACK_HDR_LEN;

	dp = dsr_pkt_alloc(NULL);

	dp->dst = dst;
	/* dp->srt = srt; */
	dp->nxt_hop = dst;	//dsr_srt_next_hop(dp->srt, 0);
	dp->src = my_addr();

	buf = dsr_pkt_alloc_opts(dp, len);

	if (!buf)
		goto out_err;

	dp->nh.iph = dsr_build_ip(dp, dp->src, dp->dst, IP_HDR_LEN,
				  IP_HDR_LEN + len, IPPROTO_DSR, IPDEFTTL);

	if (!dp->nh.iph) {
		DEBUG("Could not create IP header\n");
		goto out_err;
	}

	dp->dh.opth = dsr_opt_hdr_add(buf, len, DSR_NO_NEXT_HDR_TYPE);

	if (!dp->dh.opth) {
		DEBUG("Could not create DSR opt header\n");
		goto out_err;
	}

	buf += DSR_OPT_HDR_LEN;
	len -= DSR_OPT_HDR_LEN;

	/* dp->srt_opt = dsr_srt_opt_add(buf, len, dp->srt); */

/* 	if (!dp->srt_opt) { */
/* 		DEBUG("Could not create Source Route option header\n"); */
/* 		goto out_err; */
/* 	} */

/* 	buf += DSR_SRT_OPT_LEN(dp->srt); */
/* 	len -= DSR_SRT_OPT_LEN(dp->srt); */

	ack_opt = dsr_ack_opt_add(buf, len, dp->src, dp->dst, id);

	if (!ack_opt) {
		DEBUG("Could not create DSR ACK opt header\n");
		goto out_err;
	}

	DEBUG("Sending ACK to %s id=%u\n", print_ip(dst), id);

	dp->flags |= PKT_XMIT_JITTER;

	XMIT(dp);

	return 1;

      out_err:
	dsr_pkt_free(dp);
	return -1;
}

static struct dsr_ack_req_opt *dsr_ack_req_opt_create(char *buf, int len,
						      unsigned short id)
{
	struct dsr_ack_req_opt *ack_req = (struct dsr_ack_req_opt *)buf;

	if (len < (int)DSR_ACK_REQ_HDR_LEN)
		return NULL;

	/* Build option */
	ack_req->type = DSR_OPT_ACK_REQ;
	ack_req->length = DSR_ACK_REQ_OPT_LEN;
	ack_req->id = htons(id);

	return ack_req;
}

struct dsr_ack_req_opt *NSCLASS
dsr_ack_req_opt_add(struct dsr_pkt *dp, unsigned short id)
{
	char *buf = NULL;
	int prot = 0, tot_len = 0, ttl = IPDEFTTL;

	if (!dp)
		return NULL;

	/* If we are forwarding a packet and there is already an ACK REQ option,
	 * we just overwrite the old one. */
	if (dp->ack_req_opt) {
		buf = (char *)dp->ack_req_opt;
		goto end;
	}
#ifdef NS2
	if (dp->p) {
		hdr_cmn *cmh = HDR_CMN(dp->p);
		prot = cmh->ptype();
	} else
		prot = DSR_NO_NEXT_HDR_TYPE;

	ttl = dp->nh.iph->ttl();
#else
	if (dp->nh.raw) {
		tot_len = ntohs(dp->nh.iph->tot_len);
		prot = dp->nh.iph->protocol;
		ttl = dp->nh.iph->ttl;
	}
#endif
	if (!dsr_pkt_opts_len(dp)) {

		buf =
		    dsr_pkt_alloc_opts(dp,
				       DSR_OPT_HDR_LEN + DSR_ACK_REQ_HDR_LEN);
		DEBUG("Allocating options for ACK REQ\n");
		if (!buf)
			return NULL;

		dsr_build_ip(dp, dp->src, dp->dst, IP_HDR_LEN,
			     tot_len + DSR_OPT_HDR_LEN + DSR_ACK_REQ_HDR_LEN,
			     IPPROTO_DSR, ttl);

		dp->dh.opth =
		    dsr_opt_hdr_add(buf, DSR_OPT_HDR_LEN + DSR_ACK_REQ_HDR_LEN,
				    prot);

		if (!dp->dh.opth) {
			return NULL;
		}

		buf += DSR_OPT_HDR_LEN;

	} else {
		buf = dsr_pkt_alloc_opts_expand(dp, DSR_ACK_REQ_HDR_LEN);

		DEBUG("Expanding options for ACK REQ p_len=%d\n",
		      ntohs(dp->dh.opth->p_len));
		if (!buf)
			return NULL;

		dsr_build_ip(dp, dp->src, dp->dst, IP_HDR_LEN,
			     tot_len + DSR_ACK_REQ_HDR_LEN, IPPROTO_DSR, ttl);

		dp->dh.opth =
		    dsr_opt_hdr_add(dp->dh.raw,
				    DSR_OPT_HDR_LEN +
				    ntohs(dp->dh.opth->p_len) +
				    DSR_ACK_REQ_HDR_LEN, dp->dh.opth->nh);
	}
	DEBUG("Added ACK REQ option id=%u\n", id, ntohs(dp->dh.opth->p_len));
      end:
	return dsr_ack_req_opt_create(buf, DSR_ACK_REQ_HDR_LEN, id);
}

int NSCLASS dsr_ack_req_send(struct in_addr neigh_addr, unsigned short id)
{
	struct dsr_pkt *dp;
	struct dsr_ack_req_opt *ack_req;
	int len = DSR_OPT_HDR_LEN + DSR_ACK_REQ_HDR_LEN;
	char *buf;

	dp = dsr_pkt_alloc(NULL);

	dp->dst = neigh_addr;
	dp->nxt_hop = neigh_addr;
	dp->src = my_addr();

	buf = dsr_pkt_alloc_opts(dp, len);

	if (!buf)
		goto out_err;

	dp->nh.iph = dsr_build_ip(dp, dp->src, dp->dst, IP_HDR_LEN,
				  IP_HDR_LEN + len, IPPROTO_DSR, 1);

	if (!dp->nh.iph) {
		DEBUG("Could not create IP header\n");
		goto out_err;
	}

	dp->dh.opth = dsr_opt_hdr_add(buf, len, DSR_NO_NEXT_HDR_TYPE);

	if (!dp->dh.opth) {
		DEBUG("Could not create DSR opt header\n");
		goto out_err;
	}

	buf += DSR_OPT_HDR_LEN;
	len -= DSR_OPT_HDR_LEN;

	ack_req = dsr_ack_req_opt_create(buf, len, id);

	if (!ack_req) {
		DEBUG("Could not create ACK REQ opt\n");
		goto out_err;
	}

	DEBUG("Sending ACK REQ for %s id=%u\n", print_ip(neigh_addr), id);

	XMIT(dp);

	return 1;

      out_err:
	dsr_pkt_free(dp);
	return -1;
}

int NSCLASS dsr_ack_req_opt_recv(struct dsr_pkt *dp, struct dsr_ack_req_opt *ack_req_opt)
{
	unsigned short id;

	if (!ack_req_opt || !dp || dp->flags & PKT_PROMISC_RECV)
		return DSR_PKT_ERROR;

	dp->ack_req_opt = ack_req_opt;

	id = ntohs(ack_req_opt->id);

	if (!dp->srt_opt)
		dp->prv_hop = dp->src;

	DEBUG("src=%s prv=%s id=%u\n",
	      print_ip(dp->src), print_ip(dp->prv_hop), id);

	dsr_ack_send(dp->prv_hop, id);

	return DSR_PKT_NONE;
}

int NSCLASS dsr_ack_opt_recv(struct dsr_ack_opt *ack)
{
	unsigned short id;
	struct in_addr dst, src, myaddr;
	int n;

	if (!ack)
		return DSR_PKT_ERROR;

	myaddr = my_addr();

	dst.s_addr = ack->dst;
	src.s_addr = ack->src;
	id = ntohs(ack->id);

	DEBUG("ACK dst=%s src=%s id=%u\n", print_ip(dst), print_ip(src), id);

	if (dst.s_addr != myaddr.s_addr)
		return DSR_PKT_ERROR;

	/* Purge packets buffered for this next hop */
	n = maint_buf_del_all_id(src, id);

	DEBUG("Removed %d packets from maint buf\n", n);
	
	return DSR_PKT_NONE;
}