ip_input.c

来自「操作系统SunOS 4.1.3版本的源码」· C语言 代码 · 共 811 行 · 第 1/2 页

#ifdef	DUMP_DEBUG1
	dprint(dump_debug, 6, "ip_reass(1): q 0x%x m 0x%x t 0x%x\n", q, m, t);
#endif	 /* DUMP_DEBUG */
	m_cat(m, t);
	q = q->ipf_next;
	while (q != (struct ipasfrag *)fp) {
		t = dtom(q);
		q = q->ipf_next;
#ifdef	DUMP_DEBUG1
	dprint(dump_debug, 6, "ip_reass(2): q 0x%x m 0x%x t 0x%x\n", q, m, t);
#endif	 /* DUMP_DEBUG */
		m_cat(m, t);
	}
#ifdef  DUMP_DEBUG1
	dprint(dump_debug, 6, "ip_reass: mcat OK\n");
#endif   /* DUMP_DEBUG */

	/*
	 * Create header for new ip packet by
	 * modifying header of first packet;
	 * dequeue and discard fragment reassembly header.
	 * Make header visible.
	 */
	ip = fp->ipq_next;
	ip->ip_len = next;
	((struct ip *)ip)->ip_src = fp->ipq_src;
	((struct ip *)ip)->ip_dst = fp->ipq_dst;
	remque(fp);
	(void) m_free(dtom(fp));
	m = dtom(ip);
	m->m_len += sizeof (struct ipasfrag);
	m->m_off -= sizeof (struct ipasfrag);
	return ((struct ip *)ip);

dropfrag:
	m_freem(m);
	return (0);
}

/*
 * Free a fragment reassembly header and all
 * associated datagrams.
 */
ip_freef(fp)
	struct ipq *fp;
{
	register struct ipasfrag *q, *p;

	for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
		p = q->ipf_next;
		ip_deq(q);
		m_freem(dtom(q));
	}
	remque(fp);
	(void) m_free(dtom(fp));
}

/*
 * Put an ip fragment on a reassembly chain.
 * Like insque, but pointers in middle of structure.
 */
ip_enq(p, prev)
	register struct ipasfrag *p, *prev;
{

	p->ipf_prev = prev;
	p->ipf_next = prev->ipf_next;
	prev->ipf_next->ipf_prev = p;
	prev->ipf_next = p;
}

/*
 * To ip_enq as remque is to insque.
 */
ip_deq(p)
	register struct ipasfrag *p;
{

	p->ipf_prev->ipf_next = p->ipf_next;
	p->ipf_next->ipf_prev = p->ipf_prev;
}

/*
 * IP timer processing;
 * if a timer expires on a reassembly
 * queue, discard it.
 */
ip_slowtimo()
{
	register struct ipq *fp;
	int s = splnet();

	ip_reasstot = 0;
	fp = ipq.next;
	if (fp == 0) {
		(void) splx(s);
		return;
	}
	while (fp != &ipq) {
		ip_reasstot++;
		--fp->ipq_ttl;
		fp = fp->next;
		if (fp->prev->ipq_ttl == 0)
			ip_freef(fp->prev);
	}
	(void) splx(s);
}

/*
 * Drain off all datagram fragments.
 */
ip_drain()
{

	while (ipq.next != &ipq)
		ip_freef(ipq.next);
}


/*
 * Do option processing on a datagram,
 * possibly discarding it if bad options
 * are encountered.
 */
ip_dooptions(ip)
	struct ip *ip;
{
#ifdef NEVER
	register u_char *cp;
	int opt, optlen, cnt, code, type;
	struct in_addr *sin;
	register struct ip_timestamp *ipt;
	register struct ifnet *ifp;
	struct in_addr t;
#endif NEVER

#ifdef	DUMP_DEBUG1
	dprint(dump_debug, 0,
		"ip_dooptions(ip 0x%x)\n",
		ip);
#endif	/* DUMP_DEBUG */

#ifdef	NEVER
	cp = (u_char *)(ip + 1);
	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
	for (; cnt > 0; cnt -= optlen, cp += optlen) {
		opt = cp[0];
		if (opt == IPOPT_EOL)
			break;
		if (opt == IPOPT_NOP)
			optlen = 1;
		else
			optlen = cp[1];
		switch (opt) {

		default:
			break;

		/*
		 * Source routing with record.
		 * Find interface with current destination address.
		 * If none on this machine then drop if strictly routed,
		 * or do nothing if loosely routed.
		 * Record interface address and bring up next address
		 * component.  If strictly routed make sure next
		 * address on directly accessible net.
		 */
		case IPOPT_LSRR:
		case IPOPT_SSRR:
			if (cp[2] < 4 || cp[2] > optlen - (sizeof (long) - 1))
				break;
			sin = (struct in_addr *)(cp + cp[2]);
			ipaddr.sin_addr = *sin;
			ifp = if_ifwithaddr((struct sockaddr *)&ipaddr);
			type = ICMP_UNREACH, code = ICMP_UNREACH_SRCFAIL;
			if (ifp == 0) {
				if (opt == IPOPT_SSRR)
					goto bad;
				break;
			}
			t = ip->ip_dst; ip->ip_dst = *sin; *sin = t;
			cp[2] += 4;
			if (cp[2] > optlen - (sizeof (long) - 1))
				break;
			ip->ip_dst = sin[1];
			if (opt == IPOPT_SSRR &&
			    if_ifonnetof(in_netof(ip->ip_dst)) == 0)
				goto bad;
			break;

		case IPOPT_TS:
			code = cp - (u_char *)ip;
			type = ICMP_PARAMPROB;
			ipt = (struct ip_timestamp *)cp;
			if (ipt->ipt_len < 5)
				goto bad;
			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
				if (++ipt->ipt_oflw == 0)
					goto bad;
				break;
			}
			sin = (struct in_addr *)(cp+cp[2]);
			switch (ipt->ipt_flg) {

			case IPOPT_TS_TSONLY:
				break;

			case IPOPT_TS_TSANDADDR:
			    if (ipt->ipt_ptr + 8 > ipt->ipt_len)
				goto bad;
			    if (ifinet == 0)
				goto bad;	/* ??? */
			    *sin++ = ((struct sockaddr_in *)
				&ifinet->if_addr)->sin_addr;
			    break;

			case IPOPT_TS_PRESPEC:
			    ipaddr.sin_addr = *sin;
			    if (if_ifwithaddr((struct sockaddr *)&ipaddr) == 0)
				continue;
			    if (ipt->ipt_ptr + 8 > ipt->ipt_len)
				goto bad;
			    ipt->ipt_ptr += 4;
			    break;

			default:
			    goto bad;
			}
			*(n_time *)sin = iptime();
			ipt->ipt_ptr += 4;
		}
	}
#endif	/* NEVER */
	return (0);
#ifdef NEVER
bad:
	icmp_error(ip, type, code);
	return (1);
#endif NEVER
}

#ifdef	NEVER
/*
 * Strip out IP options, at higher
 * level protocol in the kernel.
 * Second argument is buffer to which options
 * will be moved, and return value is their length.
 */
ip_stripoptions(ip, mopt)
	struct ip *ip;
	struct mbuf *mopt;
{
	register int i;
	register struct mbuf *m;
	int olen;

	olen = (ip->ip_hl<<2) - sizeof (struct ip);
	m = dtom(ip);
	ip++;
	if (mopt) {
		mopt->m_len = olen;
		mopt->m_off = MMINOFF;
		bcopy((caddr_t)ip, mtod(m, caddr_t), (unsigned)olen);
	}
	i = m->m_len - (sizeof (struct ip) + olen);
	bcopy((caddr_t)ip+olen, (caddr_t)ip, (unsigned)i);
	m->m_len -= olen;
}

u_char inetctlerrmap[PRC_NCMDS] = {
	ECONNABORTED,	ECONNABORTED,	0,		0,
	0,		0,		EHOSTDOWN,	EHOSTUNREACH,
	ENETUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
	EMSGSIZE,	0,		0,		0,
	0,		0,		0,		0
};

ip_ctlinput(cmd, arg)
	int cmd;
	caddr_t arg;
{
	struct in_addr *in;
	int tcp_abort(), udp_abort();
	extern struct inpcb tcb, udb;

	if (cmd < 0 || cmd > PRC_NCMDS)
		return;
	if (inetctlerrmap[cmd] == 0)
		return;		/* XXX */
	if (cmd == PRC_IFDOWN)
		in = &((struct sockaddr_in *)arg)->sin_addr;
	else if (cmd == PRC_HOSTDEAD || cmd == PRC_HOSTUNREACH)
		in = (struct in_addr *)arg;
	else
		in = &((struct icmp *)arg)->icmp_ip.ip_dst;
/* THIS IS VERY QUESTIONABLE, SHOULD HIT ALL PROTOCOLS */
	in_pcbnotify(&tcb, in, (int)inetctlerrmap[cmd], tcp_abort);
	in_pcbnotify(&udb, in, (int)inetctlerrmap[cmd], udp_abort);
}
#endif	/* NEVER */

int	ipprintfs = 0;
int	ipforwarding = 1;
/*
 * Forward a packet.  If some error occurs return the sender
 * and icmp packet.  Note we can't always generate a meaningful
 * icmp message because icmp doesn't have a large enough repetoire
 * of codes and types.
 */
ip_forward(ip)
	register struct ip *ip;
{
#ifdef NEVER
	register int error, type, code;
	struct mbuf *mopt, *mcopy;
#endif NEVER

#ifdef	DUMP_DEBUG1
	dprint(dump_debug, 0,
		"ip_forward(ip 0x%x)\n",
		ip);
#endif	/* DUMP_DEBUG */

#ifdef	NEVER
	/*
	 * don't forward broadcasts which escape from the net
	 * for which they were destined  -- happens with multiple
	 * IP nets on one Ethernet
	 */
	if (in_netof(ip->ip_dst) == INADDR_ANY ||
	    (in_lnaof(ip->ip_dst) == INADDR_ANY &&
	    in_netof(ip->ip_dst) == in_netof(ip->ip_src))) {
		m_freem(dtom(ip));
		return;
	}
	if (ipprintfs)
		printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
			ip->ip_dst, ip->ip_ttl);
	if (ipforwarding == 0) {
		/* can't tell difference between net and host */
		type = ICMP_UNREACH, code = ICMP_UNREACH_NET;
		goto sendicmp;
	}
	if (ip->ip_ttl < IPTTLDEC) {
		type = ICMP_TIMXCEED, code = ICMP_TIMXCEED_INTRANS;
		goto sendicmp;
	}
	ip->ip_ttl -= IPTTLDEC;
	mopt = m_get(M_DONTWAIT, MT_DATA);
	if (mopt == NULL) {
		m_freem(dtom(ip));
		return;
	}

	/*
	 * Save at most 64 bytes of the packet in case
	 * we need to generate an ICMP message to the src.
	 */
	mcopy = m_copy(dtom(ip), 0, imin(ip->ip_len, 64));
	ip_stripoptions(ip, mopt);

	error = ip_output(dtom(ip), mopt, (struct route *)0, IP_FORWARDING);
	if (error == 0) {
		if (mcopy)
			m_freem(mcopy);
		return;
	}
	if (mcopy == NULL)
		return;
	ip = mtod(mcopy, struct ip *);
	type = ICMP_UNREACH, code = 0;		/* need ``undefined'' */
	switch (error) {

	case ENETUNREACH:
	case ENETDOWN:
		code = ICMP_UNREACH_NET;
		break;

	case EMSGSIZE:
		code = ICMP_UNREACH_NEEDFRAG;
		break;

	case EPERM:
		code = ICMP_UNREACH_PORT;
		break;

	case ENOBUFS:
		type = ICMP_SOURCEQUENCH;
		break;

	case EHOSTDOWN:
	case EHOSTUNREACH:
		code = ICMP_UNREACH_HOST;
		break;
	}
sendicmp:
	/* don't give error replies to broadcasts */
	if (in_lnaof(ip->ip_dst) == INADDR_ANY) {
		m_freem(dtom(ip));
		return;
	}
	icmp_error(ip, type, code);
#endif	/* NEVER */
}