BSD 4_3_Tahoe release

[unix-history] / usr / src / sys / netinet / ip_output.c

/*
* Copyright (c) 1982, 1986, 1988 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, 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'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
*      @(#)ip_output.c 7.13 (Berkeley) 6/29/88
*/

#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 "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

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((struct sockaddr *)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 sendorfree;
               }
               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 = cp[0];
               if (opt == IPOPT_EOL)
                       break;
               if (opt == IPOPT_NOP)
                       optlen = 1;
               else
                       optlen = 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);
}