2.11BSD/sys/netinet/ip_output.c

/*
 * Copyright (c) 1982, 1986 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 *
 *	@(#)ip_output.c	7.9 (Berkeley) 3/15/88
 */

#include "param.h"
#include "mbuf.h"
#include "errno.h"
#include "protosw.h"
#include "socket.h"
#include "socketvar.h"

#include "../net/if.h"
#include "../net/route.h"

#include "domain.h"
#include "in.h"
#include "in_pcb.h"
#include "in_systm.h"
#include "in_var.h"
#include "ip.h"
#include "ip_var.h"

#ifdef vax
#include "../machine/mtpr.h"
#endif

#define ovbcopy(a,b,c)	bcopy(a,b,c)
struct mbuf *ip_insertoptions();

/*
 * IP output.  The packet in mbuf chain m contains a skeletal IP
 * header (with len, off, ttl, proto, tos, src, dst).
 * The mbuf chain containing the packet will be freed.
 * The mbuf opt, if present, will not be freed.
 */
ip_output(m0, opt, ro, flags)
	struct mbuf *m0;
	struct mbuf *opt;
	struct route *ro;
	int flags;
{
	register struct ip *ip, *mhip;
	register struct ifnet *ifp;
	register struct mbuf *m = m0;
	register int hlen = sizeof (struct ip);
	int len, off, error = 0;
	struct route iproute;
	struct sockaddr_in *dst;

	if (opt) {
		m = ip_insertoptions(m, opt, &len);
		hlen = len;
	}
	ip = mtod(m, struct ip *);
	/*
	 * Fill in IP header.
	 */
	if ((flags & IP_FORWARDING) == 0) {
		ip->ip_v = IPVERSION;
		ip->ip_off &= IP_DF;
		ip->ip_id = htons(ip_id++);
		ip->ip_hl = hlen >> 2;
	} else
		hlen = ip->ip_hl << 2;

	/*
	 * Route packet.
	 */
	if (ro == 0) {
		ro = &iproute;
		bzero((caddr_t)ro, sizeof (*ro));
	}
	dst = (struct sockaddr_in *)&ro->ro_dst;
	/*
	 * If there is a cached route,
	 * check that it is to the same destination
	 * and is still up.  If not, free it and try again.
	 */
	if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
	   dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
		RTFREE(ro->ro_rt);
		ro->ro_rt = (struct rtentry *)0;
	}
	if (ro->ro_rt == 0) {
		dst->sin_family = AF_INET;
		dst->sin_addr = ip->ip_dst;
	}
	/*
	 * If routing to interface only,
	 * short circuit routing lookup.
	 */
	if (flags & IP_ROUTETOIF) {
		struct in_ifaddr *ia;

		ia = (struct in_ifaddr *)ifa_ifwithdstaddr(dst);
		if (ia == 0)
			ia = in_iaonnetof(in_netof(ip->ip_dst));
		if (ia == 0) {
			error = ENETUNREACH;
			goto bad;
		}
		ifp = ia->ia_ifp;
	} else {
		if (ro->ro_rt == 0)
			rtalloc(ro);
		if (ro->ro_rt == 0 || (ifp = ro->ro_rt->rt_ifp) == 0) {
			if (in_localaddr(ip->ip_dst))
				error = EHOSTUNREACH;
			else
				error = ENETUNREACH;
			goto bad;
		}
		ro->ro_rt->rt_use++;
		if (ro->ro_rt->rt_flags & RTF_GATEWAY)
			dst = (struct sockaddr_in *)&ro->ro_rt->rt_gateway;
	}
#ifndef notdef
	/*
	 * If source address not specified yet, use address
	 * of outgoing interface.
	 */
	if (ip->ip_src.s_addr == INADDR_ANY) {
		register struct in_ifaddr *ia;

		for (ia = in_ifaddr; ia; ia = ia->ia_next)
			if (ia->ia_ifp == ifp) {
				ip->ip_src = IA_SIN(ia)->sin_addr;
				break;
			}
	}
#endif
	/*
	 * Look for broadcast address and
	 * and verify user is allowed to send
	 * such a packet.
	 */
	if (in_broadcast(dst->sin_addr)) {
		if ((ifp->if_flags & IFF_BROADCAST) == 0) {
			error = EADDRNOTAVAIL;
			goto bad;
		}
		if ((flags & IP_ALLOWBROADCAST) == 0) {
			error = EACCES;
			goto bad;
		}
		/* don't allow broadcast messages to be fragmented */
		if (ip->ip_len > ifp->if_mtu) {
			error = EMSGSIZE;
			goto bad;
		}
	}

	/*
	 * If small enough for interface, can just send directly.
	 */
	if (ip->ip_len <= ifp->if_mtu) {
		ip->ip_len = htons((u_short)ip->ip_len);
		ip->ip_off = htons((u_short)ip->ip_off);
		ip->ip_sum = 0;
		ip->ip_sum = in_cksum(m, hlen);
		error = (*ifp->if_output)(ifp, m, (struct sockaddr *)dst);
		goto done;
	}

	/*
	 * Too large for interface; fragment if possible.
	 * Must be able to put at least 8 bytes per fragment.
	 */
	if (ip->ip_off & IP_DF) {
		error = EMSGSIZE;
		goto bad;
	}
	len = (ifp->if_mtu - hlen) &~ 7;
	if (len < 8) {
		error = EMSGSIZE;
		goto bad;
	}

    {
	int mhlen, firstlen = len;
	struct mbuf **mnext = &m->m_act;

	/*
	 * Loop through length of segment after first fragment,
	 * make new header and copy data of each part and link onto chain.
	 */
	m0 = m;
	mhlen = sizeof (struct ip);
	for (off = hlen + len; off < ip->ip_len; off += len) {
		MGET(m, M_DONTWAIT, MT_HEADER);
		if (m == 0) {
			error = ENOBUFS;
			goto bad;
		}
		m->m_off = MMAXOFF - hlen;
		mhip = mtod(m, struct ip *);
		*mhip = *ip;
		if (hlen > sizeof (struct ip)) {
			mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
			mhip->ip_hl = mhlen >> 2;
		}
		m->m_len = mhlen;
		mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);
		if (ip->ip_off & IP_MF)
			mhip->ip_off |= IP_MF;
		if (off + len >= ip->ip_len)
			len = ip->ip_len - off;
		else
			mhip->ip_off |= IP_MF;
		mhip->ip_len = htons((u_short)(len + mhlen));
		m->m_next = m_copy(m0, off, len);
		if (m->m_next == 0) {
			error = ENOBUFS;	/* ??? */
			goto sendorfree;
		}
		mhip->ip_off = htons((u_short)mhip->ip_off);
		mhip->ip_sum = 0;
		mhip->ip_sum = in_cksum(m, mhlen);
		*mnext = m;
		mnext = &m->m_act;
	}
	/*
	 * Update first fragment by trimming what's been copied out
	 * and updating header, then send each fragment (in order).
	 */
	m_adj(m0, hlen + firstlen - ip->ip_len);
	ip->ip_len = htons((u_short)(hlen + firstlen));
	ip->ip_off = htons((u_short)(ip->ip_off | IP_MF));
	ip->ip_sum = 0;
	ip->ip_sum = in_cksum(m0, hlen);
sendorfree:
	for (m = m0; m; m = m0) {
		m0 = m->m_act;
		m->m_act = 0;
		if (error == 0)
			error = (*ifp->if_output)(ifp, m,
			    (struct sockaddr *)dst);
		else
			m_freem(m);
	}
    }
done:
	if (ro == &iproute && (flags & IP_ROUTETOIF) == 0 && ro->ro_rt)
		RTFREE(ro->ro_rt);
	return (error);
bad:
	m_freem(m0);
	goto done;
}

/*
 * Insert IP options into preformed packet.
 * Adjust IP destination as required for IP source routing,
 * as indicated by a non-zero in_addr at the start of the options.
 */
struct mbuf *
ip_insertoptions(m, opt, phlen)
	register struct mbuf *m;
	struct mbuf *opt;
	int *phlen;
{
	register struct ipoption *p = mtod(opt, struct ipoption *);
	struct mbuf *n;
	register struct ip *ip = mtod(m, struct ip *);
	unsigned optlen;

	optlen = opt->m_len - sizeof(p->ipopt_dst);
	if (p->ipopt_dst.s_addr)
		ip->ip_dst = p->ipopt_dst;
	if (m->m_off >= MMAXOFF || MMINOFF + optlen > m->m_off) {
		MGET(n, M_DONTWAIT, MT_HEADER);
		if (n == 0)
			return (m);
		m->m_len -= sizeof(struct ip);
		m->m_off += sizeof(struct ip);
		n->m_next = m;
		m = n;
		m->m_off = MMAXOFF - sizeof(struct ip) - optlen;
		m->m_len = optlen + sizeof(struct ip);
		bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
	} else {
		m->m_off -= optlen;
		m->m_len += optlen;
		ovbcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
	}
	ip = mtod(m, struct ip *);
	bcopy((caddr_t)p->ipopt_list, (caddr_t)(ip + 1), (unsigned)optlen);
	*phlen = sizeof(struct ip) + optlen;
	ip->ip_len += optlen;
	return (m);
}

/*
 * Copy options from ip to jp,
 * omitting those not copied during fragmentation.
 */
ip_optcopy(ip, jp)
	struct ip *ip, *jp;
{
	register u_char *cp, *dp;
	int opt, optlen, cnt;

	cp = (u_char *)(ip + 1);
	dp = (u_char *)(jp + 1);
	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
	for (; cnt > 0; cnt -= optlen, cp += optlen) {
		opt = UCHAR(cp[0]);
		if (opt == IPOPT_EOL)
			break;
		if (opt == IPOPT_NOP)
			optlen = 1;
		else
			optlen = UCHAR(cp[IPOPT_OLEN]);
		/* bogus lengths should have been caught by ip_dooptions */
		if (optlen > cnt)
			optlen = cnt;
		if (IPOPT_COPIED(opt)) {
			bcopy((caddr_t)cp, (caddr_t)dp, (unsigned)optlen);
			dp += optlen;
		}
	}
	for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
		*dp++ = IPOPT_EOL;
	return (optlen);
}

/*
 * IP socket option processing.
 */
ip_ctloutput(op, so, level, optname, m)
	int op;
	struct socket *so;
	int level, optname;
	struct mbuf **m;
{
	int error = 0;
	struct inpcb *inp = sotoinpcb(so);

	if (level != IPPROTO_IP)
		error = EINVAL;
	else switch (op) {

	case PRCO_SETOPT:
		switch (optname) {
		case IP_OPTIONS:
			return (ip_pcbopts(&inp->inp_options, *m));

		default:
			error = EINVAL;
			break;
		}
		break;

	case PRCO_GETOPT:
		switch (optname) {
		case IP_OPTIONS:
			*m = m_get(M_WAIT, MT_SOOPTS);
			if (inp->inp_options) {
				(*m)->m_off = inp->inp_options->m_off;
				(*m)->m_len = inp->inp_options->m_len;
				bcopy(mtod(inp->inp_options, caddr_t),
				    mtod(*m, caddr_t), (unsigned)(*m)->m_len);
			} else
				(*m)->m_len = 0;
			break;
		default:
			error = EINVAL;
			break;
		}
		break;
	}
	if (op == PRCO_SETOPT && *m)
		(void)m_free(*m);
	return (error);
}

/*
 * Set up IP options in pcb for insertion in output packets.
 * Store in mbuf with pointer in pcbopt, adding pseudo-option
 * with destination address if source routed.
 */
ip_pcbopts(pcbopt, m)
	struct mbuf **pcbopt;
	register struct mbuf *m;
{
	register cnt, optlen;
	register u_char *cp;
	u_char opt;

	/* turn off any old options */
	if (*pcbopt)
		(void)m_free(*pcbopt);
	*pcbopt = 0;
	if (m == (struct mbuf *)0 || m->m_len == 0) {
		/*
		 * Only turning off any previous options.
		 */
		if (m)
			(void)m_free(m);
		return (0);
	}

#ifndef	vax
	if (m->m_len % sizeof(long))
		goto bad;
#endif
	/*
	 * IP first-hop destination address will be stored before
	 * actual options; move other options back
	 * and clear it when none present.
	 */
#if	MAX_IPOPTLEN >= MMAXOFF - MMINOFF
	if (m->m_off + m->m_len + sizeof(struct in_addr) > MAX_IPOPTLEN)
		goto bad;
#else
	if (m->m_off + m->m_len + sizeof(struct in_addr) > MMAXOFF)
		goto bad;
#endif
	cnt = m->m_len;
	m->m_len += sizeof(struct in_addr);
	cp = mtod(m, u_char *) + sizeof(struct in_addr);
	ovbcopy(mtod(m, caddr_t), (caddr_t)cp, (unsigned)cnt);
	bzero(mtod(m, caddr_t), sizeof(struct in_addr));

	for (; cnt > 0; cnt -= optlen, cp += optlen) {
		opt = cp[IPOPT_OPTVAL];
		if (opt == IPOPT_EOL)
			break;
		if (opt == IPOPT_NOP)
			optlen = 1;
		else {
			optlen = cp[IPOPT_OLEN];
			if (optlen <= IPOPT_OLEN || optlen > cnt)
				goto bad;
		}
		switch (opt) {

		default:
			break;

		case IPOPT_LSRR:
		case IPOPT_SSRR:
			/*
			 * user process specifies route as:
			 *	->A->B->C->D
			 * D must be our final destination (but we can't
			 * check that since we may not have connected yet).
			 * A is first hop destination, which doesn't appear in
			 * actual IP option, but is stored before the options.
			 */
			if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
				goto bad;
			m->m_len -= sizeof(struct in_addr);
			cnt -= sizeof(struct in_addr);
			optlen -= sizeof(struct in_addr);
			cp[IPOPT_OLEN] = optlen;
			/*
			 * Move first hop before start of options.
			 */
			bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
			    sizeof(struct in_addr));
			/*
			 * Then copy rest of options back
			 * to close up the deleted entry.
			 */
			ovbcopy((caddr_t)(&cp[IPOPT_OFFSET+1] +
			    sizeof(struct in_addr)),
			    (caddr_t)&cp[IPOPT_OFFSET+1],
			    (unsigned)cnt + sizeof(struct in_addr));
			break;
		}
	}
	*pcbopt = m;
	return (0);

bad:
	(void)m_free(m);
	return (EINVAL);
}