The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_output.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1990, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)ip_output.c 8.3 (Berkeley) 1/21/94
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/9.0/sys/netinet/ip_output.c 227428 2011-11-10 20:28:30Z trociny $");
   34 
   35 #include "opt_ipfw.h"
   36 #include "opt_ipsec.h"
   37 #include "opt_route.h"
   38 #include "opt_mbuf_stress_test.h"
   39 #include "opt_mpath.h"
   40 #include "opt_sctp.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/kernel.h>
   45 #include <sys/malloc.h>
   46 #include <sys/mbuf.h>
   47 #include <sys/priv.h>
   48 #include <sys/proc.h>
   49 #include <sys/protosw.h>
   50 #include <sys/socket.h>
   51 #include <sys/socketvar.h>
   52 #include <sys/sysctl.h>
   53 #include <sys/ucred.h>
   54 
   55 #include <net/if.h>
   56 #include <net/if_llatbl.h>
   57 #include <net/netisr.h>
   58 #include <net/pfil.h>
   59 #include <net/route.h>
   60 #include <net/flowtable.h>
   61 #ifdef RADIX_MPATH
   62 #include <net/radix_mpath.h>
   63 #endif
   64 #include <net/vnet.h>
   65 
   66 #include <netinet/in.h>
   67 #include <netinet/in_systm.h>
   68 #include <netinet/ip.h>
   69 #include <netinet/in_pcb.h>
   70 #include <netinet/in_var.h>
   71 #include <netinet/ip_var.h>
   72 #include <netinet/ip_options.h>
   73 #ifdef SCTP
   74 #include <netinet/sctp.h>
   75 #include <netinet/sctp_crc32.h>
   76 #endif
   77 
   78 #ifdef IPSEC
   79 #include <netinet/ip_ipsec.h>
   80 #include <netipsec/ipsec.h>
   81 #endif /* IPSEC*/
   82 
   83 #include <machine/in_cksum.h>
   84 
   85 #include <security/mac/mac_framework.h>
   86 
   87 VNET_DEFINE(u_short, ip_id);
   88 
   89 #ifdef MBUF_STRESS_TEST
   90 static int mbuf_frag_size = 0;
   91 SYSCTL_INT(_net_inet_ip, OID_AUTO, mbuf_frag_size, CTLFLAG_RW,
   92         &mbuf_frag_size, 0, "Fragment outgoing mbufs to this size");
   93 #endif
   94 
   95 static void     ip_mloopback
   96         (struct ifnet *, struct mbuf *, struct sockaddr_in *, int);
   97 
   98 
   99 extern int in_mcast_loop;
  100 extern  struct protosw inetsw[];
  101 
  102 /*
  103  * IP output.  The packet in mbuf chain m contains a skeletal IP
  104  * header (with len, off, ttl, proto, tos, src, dst).
  105  * ip_len and ip_off are in host format.
  106  * The mbuf chain containing the packet will be freed.
  107  * The mbuf opt, if present, will not be freed.
  108  * In the IP forwarding case, the packet will arrive with options already
  109  * inserted, so must have a NULL opt pointer.
  110  */
  111 int
  112 ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro, int flags,
  113     struct ip_moptions *imo, struct inpcb *inp)
  114 {
  115         struct ip *ip;
  116         struct ifnet *ifp = NULL;       /* keep compiler happy */
  117         struct mbuf *m0;
  118         int hlen = sizeof (struct ip);
  119         int mtu;
  120         int n;  /* scratchpad */
  121         int error = 0;
  122         int nortfree = 0;
  123         struct sockaddr_in *dst;
  124         struct in_ifaddr *ia = NULL;
  125         int isbroadcast, sw_csum;
  126         struct route iproute;
  127         struct rtentry *rte;    /* cache for ro->ro_rt */
  128         struct in_addr odst;
  129 #ifdef IPFIREWALL_FORWARD
  130         struct m_tag *fwd_tag = NULL;
  131 #endif
  132 #ifdef IPSEC
  133         int no_route_but_check_spd = 0;
  134 #endif
  135         M_ASSERTPKTHDR(m);
  136 
  137         if (inp != NULL) {
  138                 INP_LOCK_ASSERT(inp);
  139                 M_SETFIB(m, inp->inp_inc.inc_fibnum);
  140                 if (inp->inp_flags & (INP_HW_FLOWID|INP_SW_FLOWID)) {
  141                         m->m_pkthdr.flowid = inp->inp_flowid;
  142                         m->m_flags |= M_FLOWID;
  143                 }
  144         }
  145 
  146         if (ro == NULL) {
  147                 ro = &iproute;
  148                 bzero(ro, sizeof (*ro));
  149 
  150 #ifdef FLOWTABLE
  151                 {
  152                         struct flentry *fle;
  153                         
  154                         /*
  155                          * The flow table returns route entries valid for up to 30
  156                          * seconds; we rely on the remainder of ip_output() taking no
  157                          * longer than that long for the stability of ro_rt.  The
  158                          * flow ID assignment must have happened before this point.
  159                          */
  160                         if ((fle = flowtable_lookup_mbuf(V_ip_ft, m, AF_INET)) != NULL) {
  161                                 flow_to_route(fle, ro);
  162                                 nortfree = 1;
  163                         }
  164                 }
  165 #endif
  166         }
  167 
  168         if (opt) {
  169                 int len = 0;
  170                 m = ip_insertoptions(m, opt, &len);
  171                 if (len != 0)
  172                         hlen = len; /* ip->ip_hl is updated above */
  173         }
  174         ip = mtod(m, struct ip *);
  175 
  176         /*
  177          * Fill in IP header.  If we are not allowing fragmentation,
  178          * then the ip_id field is meaningless, but we don't set it
  179          * to zero.  Doing so causes various problems when devices along
  180          * the path (routers, load balancers, firewalls, etc.) illegally
  181          * disable DF on our packet.  Note that a 16-bit counter
  182          * will wrap around in less than 10 seconds at 100 Mbit/s on a
  183          * medium with MTU 1500.  See Steven M. Bellovin, "A Technique
  184          * for Counting NATted Hosts", Proc. IMW'02, available at
  185          * <http://www.cs.columbia.edu/~smb/papers/fnat.pdf>.
  186          */
  187         if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
  188                 ip->ip_v = IPVERSION;
  189                 ip->ip_hl = hlen >> 2;
  190                 ip->ip_id = ip_newid();
  191                 IPSTAT_INC(ips_localout);
  192         } else {
  193                 /* Header already set, fetch hlen from there */
  194                 hlen = ip->ip_hl << 2;
  195         }
  196 
  197         dst = (struct sockaddr_in *)&ro->ro_dst;
  198 again:
  199         /*
  200          * If there is a cached route,
  201          * check that it is to the same destination
  202          * and is still up.  If not, free it and try again.
  203          * The address family should also be checked in case of sharing the
  204          * cache with IPv6.
  205          */
  206         rte = ro->ro_rt;
  207         if (rte && ((rte->rt_flags & RTF_UP) == 0 ||
  208                     rte->rt_ifp == NULL ||
  209                     !RT_LINK_IS_UP(rte->rt_ifp) ||
  210                           dst->sin_family != AF_INET ||
  211                           dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
  212                 if (!nortfree)
  213                         RTFREE(rte);
  214                 rte = ro->ro_rt = (struct rtentry *)NULL;
  215                 ro->ro_lle = (struct llentry *)NULL;
  216         }
  217 #ifdef IPFIREWALL_FORWARD
  218         if (rte == NULL && fwd_tag == NULL) {
  219 #else
  220         if (rte == NULL) {
  221 #endif
  222                 bzero(dst, sizeof(*dst));
  223                 dst->sin_family = AF_INET;
  224                 dst->sin_len = sizeof(*dst);
  225                 dst->sin_addr = ip->ip_dst;
  226         }
  227         /*
  228          * If routing to interface only, short circuit routing lookup.
  229          * The use of an all-ones broadcast address implies this; an
  230          * interface is specified by the broadcast address of an interface,
  231          * or the destination address of a ptp interface.
  232          */
  233         if (flags & IP_SENDONES) {
  234                 if ((ia = ifatoia(ifa_ifwithbroadaddr(sintosa(dst)))) == NULL &&
  235                     (ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL) {
  236                         IPSTAT_INC(ips_noroute);
  237                         error = ENETUNREACH;
  238                         goto bad;
  239                 }
  240                 ip->ip_dst.s_addr = INADDR_BROADCAST;
  241                 dst->sin_addr = ip->ip_dst;
  242                 ifp = ia->ia_ifp;
  243                 ip->ip_ttl = 1;
  244                 isbroadcast = 1;
  245         } else if (flags & IP_ROUTETOIF) {
  246                 if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL &&
  247                     (ia = ifatoia(ifa_ifwithnet(sintosa(dst), 0))) == NULL) {
  248                         IPSTAT_INC(ips_noroute);
  249                         error = ENETUNREACH;
  250                         goto bad;
  251                 }
  252                 ifp = ia->ia_ifp;
  253                 ip->ip_ttl = 1;
  254                 isbroadcast = in_broadcast(dst->sin_addr, ifp);
  255         } else if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) &&
  256             imo != NULL && imo->imo_multicast_ifp != NULL) {
  257                 /*
  258                  * Bypass the normal routing lookup for multicast
  259                  * packets if the interface is specified.
  260                  */
  261                 ifp = imo->imo_multicast_ifp;
  262                 IFP_TO_IA(ifp, ia);
  263                 isbroadcast = 0;        /* fool gcc */
  264         } else {
  265                 /*
  266                  * We want to do any cloning requested by the link layer,
  267                  * as this is probably required in all cases for correct
  268                  * operation (as it is for ARP).
  269                  */
  270                 if (rte == NULL) {
  271 #ifdef RADIX_MPATH
  272                         rtalloc_mpath_fib(ro,
  273                             ntohl(ip->ip_src.s_addr ^ ip->ip_dst.s_addr),
  274                             inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
  275 #else
  276                         in_rtalloc_ign(ro, 0,
  277                             inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
  278 #endif
  279                         rte = ro->ro_rt;
  280                 }
  281                 if (rte == NULL ||
  282                     rte->rt_ifp == NULL ||
  283                     !RT_LINK_IS_UP(rte->rt_ifp)) {
  284 #ifdef IPSEC
  285                         /*
  286                          * There is no route for this packet, but it is
  287                          * possible that a matching SPD entry exists.
  288                          */
  289                         no_route_but_check_spd = 1;
  290                         mtu = 0; /* Silence GCC warning. */
  291                         goto sendit;
  292 #endif
  293                         IPSTAT_INC(ips_noroute);
  294                         error = EHOSTUNREACH;
  295                         goto bad;
  296                 }
  297                 ia = ifatoia(rte->rt_ifa);
  298                 ifa_ref(&ia->ia_ifa);
  299                 ifp = rte->rt_ifp;
  300                 rte->rt_rmx.rmx_pksent++;
  301                 if (rte->rt_flags & RTF_GATEWAY)
  302                         dst = (struct sockaddr_in *)rte->rt_gateway;
  303                 if (rte->rt_flags & RTF_HOST)
  304                         isbroadcast = (rte->rt_flags & RTF_BROADCAST);
  305                 else
  306                         isbroadcast = in_broadcast(dst->sin_addr, ifp);
  307         }
  308         /*
  309          * Calculate MTU.  If we have a route that is up, use that,
  310          * otherwise use the interface's MTU.
  311          */
  312         if (rte != NULL && (rte->rt_flags & (RTF_UP|RTF_HOST))) {
  313                 /*
  314                  * This case can happen if the user changed the MTU
  315                  * of an interface after enabling IP on it.  Because
  316                  * most netifs don't keep track of routes pointing to
  317                  * them, there is no way for one to update all its
  318                  * routes when the MTU is changed.
  319                  */
  320                 if (rte->rt_rmx.rmx_mtu > ifp->if_mtu)
  321                         rte->rt_rmx.rmx_mtu = ifp->if_mtu;
  322                 mtu = rte->rt_rmx.rmx_mtu;
  323         } else {
  324                 mtu = ifp->if_mtu;
  325         }
  326         /* Catch a possible divide by zero later. */
  327         KASSERT(mtu > 0, ("%s: mtu %d <= 0, rte=%p (rt_flags=0x%08x) ifp=%p",
  328             __func__, mtu, rte, (rte != NULL) ? rte->rt_flags : 0, ifp));
  329         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
  330                 m->m_flags |= M_MCAST;
  331                 /*
  332                  * IP destination address is multicast.  Make sure "dst"
  333                  * still points to the address in "ro".  (It may have been
  334                  * changed to point to a gateway address, above.)
  335                  */
  336                 dst = (struct sockaddr_in *)&ro->ro_dst;
  337                 /*
  338                  * See if the caller provided any multicast options
  339                  */
  340                 if (imo != NULL) {
  341                         ip->ip_ttl = imo->imo_multicast_ttl;
  342                         if (imo->imo_multicast_vif != -1)
  343                                 ip->ip_src.s_addr =
  344                                     ip_mcast_src ?
  345                                     ip_mcast_src(imo->imo_multicast_vif) :
  346                                     INADDR_ANY;
  347                 } else
  348                         ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
  349                 /*
  350                  * Confirm that the outgoing interface supports multicast.
  351                  */
  352                 if ((imo == NULL) || (imo->imo_multicast_vif == -1)) {
  353                         if ((ifp->if_flags & IFF_MULTICAST) == 0) {
  354                                 IPSTAT_INC(ips_noroute);
  355                                 error = ENETUNREACH;
  356                                 goto bad;
  357                         }
  358                 }
  359                 /*
  360                  * If source address not specified yet, use address
  361                  * of outgoing interface.
  362                  */
  363                 if (ip->ip_src.s_addr == INADDR_ANY) {
  364                         /* Interface may have no addresses. */
  365                         if (ia != NULL)
  366                                 ip->ip_src = IA_SIN(ia)->sin_addr;
  367                 }
  368 
  369                 if ((imo == NULL && in_mcast_loop) ||
  370                     (imo && imo->imo_multicast_loop)) {
  371                         /*
  372                          * Loop back multicast datagram if not expressly
  373                          * forbidden to do so, even if we are not a member
  374                          * of the group; ip_input() will filter it later,
  375                          * thus deferring a hash lookup and mutex acquisition
  376                          * at the expense of a cheap copy using m_copym().
  377                          */
  378                         ip_mloopback(ifp, m, dst, hlen);
  379                 } else {
  380                         /*
  381                          * If we are acting as a multicast router, perform
  382                          * multicast forwarding as if the packet had just
  383                          * arrived on the interface to which we are about
  384                          * to send.  The multicast forwarding function
  385                          * recursively calls this function, using the
  386                          * IP_FORWARDING flag to prevent infinite recursion.
  387                          *
  388                          * Multicasts that are looped back by ip_mloopback(),
  389                          * above, will be forwarded by the ip_input() routine,
  390                          * if necessary.
  391                          */
  392                         if (V_ip_mrouter && (flags & IP_FORWARDING) == 0) {
  393                                 /*
  394                                  * If rsvp daemon is not running, do not
  395                                  * set ip_moptions. This ensures that the packet
  396                                  * is multicast and not just sent down one link
  397                                  * as prescribed by rsvpd.
  398                                  */
  399                                 if (!V_rsvp_on)
  400                                         imo = NULL;
  401                                 if (ip_mforward &&
  402                                     ip_mforward(ip, ifp, m, imo) != 0) {
  403                                         m_freem(m);
  404                                         goto done;
  405                                 }
  406                         }
  407                 }
  408 
  409                 /*
  410                  * Multicasts with a time-to-live of zero may be looped-
  411                  * back, above, but must not be transmitted on a network.
  412                  * Also, multicasts addressed to the loopback interface
  413                  * are not sent -- the above call to ip_mloopback() will
  414                  * loop back a copy. ip_input() will drop the copy if
  415                  * this host does not belong to the destination group on
  416                  * the loopback interface.
  417                  */
  418                 if (ip->ip_ttl == 0 || ifp->if_flags & IFF_LOOPBACK) {
  419                         m_freem(m);
  420                         goto done;
  421                 }
  422 
  423                 goto sendit;
  424         }
  425 
  426         /*
  427          * If the source address is not specified yet, use the address
  428          * of the outoing interface.
  429          */
  430         if (ip->ip_src.s_addr == INADDR_ANY) {
  431                 /* Interface may have no addresses. */
  432                 if (ia != NULL) {
  433                         ip->ip_src = IA_SIN(ia)->sin_addr;
  434                 }
  435         }
  436 
  437         /*
  438          * Verify that we have any chance at all of being able to queue the
  439          * packet or packet fragments, unless ALTQ is enabled on the given
  440          * interface in which case packetdrop should be done by queueing.
  441          */
  442         n = ip->ip_len / mtu + 1; /* how many fragments ? */
  443         if (
  444 #ifdef ALTQ
  445             (!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
  446 #endif /* ALTQ */
  447             (ifp->if_snd.ifq_len + n) >= ifp->if_snd.ifq_maxlen ) {
  448                 error = ENOBUFS;
  449                 IPSTAT_INC(ips_odropped);
  450                 ifp->if_snd.ifq_drops += n;
  451                 goto bad;
  452         }
  453 
  454         /*
  455          * Look for broadcast address and
  456          * verify user is allowed to send
  457          * such a packet.
  458          */
  459         if (isbroadcast) {
  460                 if ((ifp->if_flags & IFF_BROADCAST) == 0) {
  461                         error = EADDRNOTAVAIL;
  462                         goto bad;
  463                 }
  464                 if ((flags & IP_ALLOWBROADCAST) == 0) {
  465                         error = EACCES;
  466                         goto bad;
  467                 }
  468                 /* don't allow broadcast messages to be fragmented */
  469                 if (ip->ip_len > mtu) {
  470                         error = EMSGSIZE;
  471                         goto bad;
  472                 }
  473                 m->m_flags |= M_BCAST;
  474         } else {
  475                 m->m_flags &= ~M_BCAST;
  476         }
  477 
  478 sendit:
  479 #ifdef IPSEC
  480         switch(ip_ipsec_output(&m, inp, &flags, &error)) {
  481         case 1:
  482                 goto bad;
  483         case -1:
  484                 goto done;
  485         case 0:
  486         default:
  487                 break;  /* Continue with packet processing. */
  488         }
  489         /*
  490          * Check if there was a route for this packet; return error if not.
  491          */
  492         if (no_route_but_check_spd) {
  493                 IPSTAT_INC(ips_noroute);
  494                 error = EHOSTUNREACH;
  495                 goto bad;
  496         }
  497         /* Update variables that are affected by ipsec4_output(). */
  498         ip = mtod(m, struct ip *);
  499         hlen = ip->ip_hl << 2;
  500 #endif /* IPSEC */
  501 
  502         /* Jump over all PFIL processing if hooks are not active. */
  503         if (!PFIL_HOOKED(&V_inet_pfil_hook))
  504                 goto passout;
  505 
  506         /* Run through list of hooks for output packets. */
  507         odst.s_addr = ip->ip_dst.s_addr;
  508         error = pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_OUT, inp);
  509         if (error != 0 || m == NULL)
  510                 goto done;
  511 
  512         ip = mtod(m, struct ip *);
  513 
  514         /* See if destination IP address was changed by packet filter. */
  515         if (odst.s_addr != ip->ip_dst.s_addr) {
  516                 m->m_flags |= M_SKIP_FIREWALL;
  517                 /* If destination is now ourself drop to ip_input(). */
  518                 if (in_localip(ip->ip_dst)) {
  519                         m->m_flags |= M_FASTFWD_OURS;
  520                         if (m->m_pkthdr.rcvif == NULL)
  521                                 m->m_pkthdr.rcvif = V_loif;
  522                         if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  523                                 m->m_pkthdr.csum_flags |=
  524                                     CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
  525                                 m->m_pkthdr.csum_data = 0xffff;
  526                         }
  527                         m->m_pkthdr.csum_flags |=
  528                             CSUM_IP_CHECKED | CSUM_IP_VALID;
  529 #ifdef SCTP
  530                         if (m->m_pkthdr.csum_flags & CSUM_SCTP)
  531                                 m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
  532 #endif
  533                         error = netisr_queue(NETISR_IP, m);
  534                         goto done;
  535                 } else
  536                         goto again;     /* Redo the routing table lookup. */
  537         }
  538 
  539 #ifdef IPFIREWALL_FORWARD
  540         /* See if local, if yes, send it to netisr with IP_FASTFWD_OURS. */
  541         if (m->m_flags & M_FASTFWD_OURS) {
  542                 if (m->m_pkthdr.rcvif == NULL)
  543                         m->m_pkthdr.rcvif = V_loif;
  544                 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  545                         m->m_pkthdr.csum_flags |=
  546                             CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
  547                         m->m_pkthdr.csum_data = 0xffff;
  548                 }
  549 #ifdef SCTP
  550                 if (m->m_pkthdr.csum_flags & CSUM_SCTP)
  551                         m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
  552 #endif
  553                 m->m_pkthdr.csum_flags |=
  554                             CSUM_IP_CHECKED | CSUM_IP_VALID;
  555 
  556                 error = netisr_queue(NETISR_IP, m);
  557                 goto done;
  558         }
  559         /* Or forward to some other address? */
  560         fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
  561         if (fwd_tag) {
  562                 dst = (struct sockaddr_in *)&ro->ro_dst;
  563                 bcopy((fwd_tag+1), dst, sizeof(struct sockaddr_in));
  564                 m->m_flags |= M_SKIP_FIREWALL;
  565                 m_tag_delete(m, fwd_tag);
  566                 goto again;
  567         }
  568 #endif /* IPFIREWALL_FORWARD */
  569 
  570 passout:
  571         /* 127/8 must not appear on wire - RFC1122. */
  572         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
  573             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
  574                 if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
  575                         IPSTAT_INC(ips_badaddr);
  576                         error = EADDRNOTAVAIL;
  577                         goto bad;
  578                 }
  579         }
  580 
  581         m->m_pkthdr.csum_flags |= CSUM_IP;
  582         sw_csum = m->m_pkthdr.csum_flags & ~ifp->if_hwassist;
  583         if (sw_csum & CSUM_DELAY_DATA) {
  584                 in_delayed_cksum(m);
  585                 sw_csum &= ~CSUM_DELAY_DATA;
  586         }
  587 #ifdef SCTP
  588         if (sw_csum & CSUM_SCTP) {
  589                 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
  590                 sw_csum &= ~CSUM_SCTP;
  591         }
  592 #endif
  593         m->m_pkthdr.csum_flags &= ifp->if_hwassist;
  594 
  595         /*
  596          * If small enough for interface, or the interface will take
  597          * care of the fragmentation for us, we can just send directly.
  598          */
  599         if (ip->ip_len <= mtu ||
  600             (m->m_pkthdr.csum_flags & ifp->if_hwassist & CSUM_TSO) != 0 ||
  601             ((ip->ip_off & IP_DF) == 0 && (ifp->if_hwassist & CSUM_FRAGMENT))) {
  602                 ip->ip_len = htons(ip->ip_len);
  603                 ip->ip_off = htons(ip->ip_off);
  604                 ip->ip_sum = 0;
  605                 if (sw_csum & CSUM_DELAY_IP)
  606                         ip->ip_sum = in_cksum(m, hlen);
  607 
  608                 /*
  609                  * Record statistics for this interface address.
  610                  * With CSUM_TSO the byte/packet count will be slightly
  611                  * incorrect because we count the IP+TCP headers only
  612                  * once instead of for every generated packet.
  613                  */
  614                 if (!(flags & IP_FORWARDING) && ia) {
  615                         if (m->m_pkthdr.csum_flags & CSUM_TSO)
  616                                 ia->ia_ifa.if_opackets +=
  617                                     m->m_pkthdr.len / m->m_pkthdr.tso_segsz;
  618                         else
  619                                 ia->ia_ifa.if_opackets++;
  620                         ia->ia_ifa.if_obytes += m->m_pkthdr.len;
  621                 }
  622 #ifdef MBUF_STRESS_TEST
  623                 if (mbuf_frag_size && m->m_pkthdr.len > mbuf_frag_size)
  624                         m = m_fragment(m, M_DONTWAIT, mbuf_frag_size);
  625 #endif
  626                 /*
  627                  * Reset layer specific mbuf flags
  628                  * to avoid confusing lower layers.
  629                  */
  630                 m->m_flags &= ~(M_PROTOFLAGS);
  631                 error = (*ifp->if_output)(ifp, m,
  632                                 (struct sockaddr *)dst, ro);
  633                 goto done;
  634         }
  635 
  636         /* Balk when DF bit is set or the interface didn't support TSO. */
  637         if ((ip->ip_off & IP_DF) || (m->m_pkthdr.csum_flags & CSUM_TSO)) {
  638                 error = EMSGSIZE;
  639                 IPSTAT_INC(ips_cantfrag);
  640                 goto bad;
  641         }
  642 
  643         /*
  644          * Too large for interface; fragment if possible. If successful,
  645          * on return, m will point to a list of packets to be sent.
  646          */
  647         error = ip_fragment(ip, &m, mtu, ifp->if_hwassist, sw_csum);
  648         if (error)
  649                 goto bad;
  650         for (; m; m = m0) {
  651                 m0 = m->m_nextpkt;
  652                 m->m_nextpkt = 0;
  653                 if (error == 0) {
  654                         /* Record statistics for this interface address. */
  655                         if (ia != NULL) {
  656                                 ia->ia_ifa.if_opackets++;
  657                                 ia->ia_ifa.if_obytes += m->m_pkthdr.len;
  658                         }
  659                         /*
  660                          * Reset layer specific mbuf flags
  661                          * to avoid confusing upper layers.
  662                          */
  663                         m->m_flags &= ~(M_PROTOFLAGS);
  664 
  665                         error = (*ifp->if_output)(ifp, m,
  666                             (struct sockaddr *)dst, ro);
  667                 } else
  668                         m_freem(m);
  669         }
  670 
  671         if (error == 0)
  672                 IPSTAT_INC(ips_fragmented);
  673 
  674 done:
  675         if (ro == &iproute && ro->ro_rt && !nortfree) {
  676                 RTFREE(ro->ro_rt);
  677         }
  678         if (ia != NULL)
  679                 ifa_free(&ia->ia_ifa);
  680         return (error);
  681 bad:
  682         m_freem(m);
  683         goto done;
  684 }
  685 
  686 /*
  687  * Create a chain of fragments which fit the given mtu. m_frag points to the
  688  * mbuf to be fragmented; on return it points to the chain with the fragments.
  689  * Return 0 if no error. If error, m_frag may contain a partially built
  690  * chain of fragments that should be freed by the caller.
  691  *
  692  * if_hwassist_flags is the hw offload capabilities (see if_data.ifi_hwassist)
  693  * sw_csum contains the delayed checksums flags (e.g., CSUM_DELAY_IP).
  694  */
  695 int
  696 ip_fragment(struct ip *ip, struct mbuf **m_frag, int mtu,
  697     u_long if_hwassist_flags, int sw_csum)
  698 {
  699         int error = 0;
  700         int hlen = ip->ip_hl << 2;
  701         int len = (mtu - hlen) & ~7;    /* size of payload in each fragment */
  702         int off;
  703         struct mbuf *m0 = *m_frag;      /* the original packet          */
  704         int firstlen;
  705         struct mbuf **mnext;
  706         int nfrags;
  707 
  708         if (ip->ip_off & IP_DF) {       /* Fragmentation not allowed */
  709                 IPSTAT_INC(ips_cantfrag);
  710                 return EMSGSIZE;
  711         }
  712 
  713         /*
  714          * Must be able to put at least 8 bytes per fragment.
  715          */
  716         if (len < 8)
  717                 return EMSGSIZE;
  718 
  719         /*
  720          * If the interface will not calculate checksums on
  721          * fragmented packets, then do it here.
  722          */
  723         if (m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA &&
  724             (if_hwassist_flags & CSUM_IP_FRAGS) == 0) {
  725                 in_delayed_cksum(m0);
  726                 m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  727         }
  728 #ifdef SCTP
  729         if (m0->m_pkthdr.csum_flags & CSUM_SCTP &&
  730             (if_hwassist_flags & CSUM_IP_FRAGS) == 0) {
  731                 sctp_delayed_cksum(m0, hlen);
  732                 m0->m_pkthdr.csum_flags &= ~CSUM_SCTP;
  733         }
  734 #endif
  735         if (len > PAGE_SIZE) {
  736                 /* 
  737                  * Fragment large datagrams such that each segment 
  738                  * contains a multiple of PAGE_SIZE amount of data, 
  739                  * plus headers. This enables a receiver to perform 
  740                  * page-flipping zero-copy optimizations.
  741                  *
  742                  * XXX When does this help given that sender and receiver
  743                  * could have different page sizes, and also mtu could
  744                  * be less than the receiver's page size ?
  745                  */
  746                 int newlen;
  747                 struct mbuf *m;
  748 
  749                 for (m = m0, off = 0; m && (off+m->m_len) <= mtu; m = m->m_next)
  750                         off += m->m_len;
  751 
  752                 /*
  753                  * firstlen (off - hlen) must be aligned on an 
  754                  * 8-byte boundary
  755                  */
  756                 if (off < hlen)
  757                         goto smart_frag_failure;
  758                 off = ((off - hlen) & ~7) + hlen;
  759                 newlen = (~PAGE_MASK) & mtu;
  760                 if ((newlen + sizeof (struct ip)) > mtu) {
  761                         /* we failed, go back the default */
  762 smart_frag_failure:
  763                         newlen = len;
  764                         off = hlen + len;
  765                 }
  766                 len = newlen;
  767 
  768         } else {
  769                 off = hlen + len;
  770         }
  771 
  772         firstlen = off - hlen;
  773         mnext = &m0->m_nextpkt;         /* pointer to next packet */
  774 
  775         /*
  776          * Loop through length of segment after first fragment,
  777          * make new header and copy data of each part and link onto chain.
  778          * Here, m0 is the original packet, m is the fragment being created.
  779          * The fragments are linked off the m_nextpkt of the original
  780          * packet, which after processing serves as the first fragment.
  781          */
  782         for (nfrags = 1; off < ip->ip_len; off += len, nfrags++) {
  783                 struct ip *mhip;        /* ip header on the fragment */
  784                 struct mbuf *m;
  785                 int mhlen = sizeof (struct ip);
  786 
  787                 MGETHDR(m, M_DONTWAIT, MT_DATA);
  788                 if (m == NULL) {
  789                         error = ENOBUFS;
  790                         IPSTAT_INC(ips_odropped);
  791                         goto done;
  792                 }
  793                 m->m_flags |= (m0->m_flags & M_MCAST) | M_FRAG;
  794                 /*
  795                  * In the first mbuf, leave room for the link header, then
  796                  * copy the original IP header including options. The payload
  797                  * goes into an additional mbuf chain returned by m_copym().
  798                  */
  799                 m->m_data += max_linkhdr;
  800                 mhip = mtod(m, struct ip *);
  801                 *mhip = *ip;
  802                 if (hlen > sizeof (struct ip)) {
  803                         mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
  804                         mhip->ip_v = IPVERSION;
  805                         mhip->ip_hl = mhlen >> 2;
  806                 }
  807                 m->m_len = mhlen;
  808                 /* XXX do we need to add ip->ip_off below ? */
  809                 mhip->ip_off = ((off - hlen) >> 3) + ip->ip_off;
  810                 if (off + len >= ip->ip_len) {  /* last fragment */
  811                         len = ip->ip_len - off;
  812                         m->m_flags |= M_LASTFRAG;
  813                 } else
  814                         mhip->ip_off |= IP_MF;
  815                 mhip->ip_len = htons((u_short)(len + mhlen));
  816                 m->m_next = m_copym(m0, off, len, M_DONTWAIT);
  817                 if (m->m_next == NULL) {        /* copy failed */
  818                         m_free(m);
  819                         error = ENOBUFS;        /* ??? */
  820                         IPSTAT_INC(ips_odropped);
  821                         goto done;
  822                 }
  823                 m->m_pkthdr.len = mhlen + len;
  824                 m->m_pkthdr.rcvif = NULL;
  825 #ifdef MAC
  826                 mac_netinet_fragment(m0, m);
  827 #endif
  828                 m->m_pkthdr.csum_flags = m0->m_pkthdr.csum_flags;
  829                 mhip->ip_off = htons(mhip->ip_off);
  830                 mhip->ip_sum = 0;
  831                 if (sw_csum & CSUM_DELAY_IP)
  832                         mhip->ip_sum = in_cksum(m, mhlen);
  833                 *mnext = m;
  834                 mnext = &m->m_nextpkt;
  835         }
  836         IPSTAT_ADD(ips_ofragments, nfrags);
  837 
  838         /* set first marker for fragment chain */
  839         m0->m_flags |= M_FIRSTFRAG | M_FRAG;
  840         m0->m_pkthdr.csum_data = nfrags;
  841 
  842         /*
  843          * Update first fragment by trimming what's been copied out
  844          * and updating header.
  845          */
  846         m_adj(m0, hlen + firstlen - ip->ip_len);
  847         m0->m_pkthdr.len = hlen + firstlen;
  848         ip->ip_len = htons((u_short)m0->m_pkthdr.len);
  849         ip->ip_off |= IP_MF;
  850         ip->ip_off = htons(ip->ip_off);
  851         ip->ip_sum = 0;
  852         if (sw_csum & CSUM_DELAY_IP)
  853                 ip->ip_sum = in_cksum(m0, hlen);
  854 
  855 done:
  856         *m_frag = m0;
  857         return error;
  858 }
  859 
  860 void
  861 in_delayed_cksum(struct mbuf *m)
  862 {
  863         struct ip *ip;
  864         u_short csum, offset;
  865 
  866         ip = mtod(m, struct ip *);
  867         offset = ip->ip_hl << 2 ;
  868         csum = in_cksum_skip(m, ip->ip_len, offset);
  869         if (m->m_pkthdr.csum_flags & CSUM_UDP && csum == 0)
  870                 csum = 0xffff;
  871         offset += m->m_pkthdr.csum_data;        /* checksum offset */
  872 
  873         if (offset + sizeof(u_short) > m->m_len) {
  874                 printf("delayed m_pullup, m->len: %d  off: %d  p: %d\n",
  875                     m->m_len, offset, ip->ip_p);
  876                 /*
  877                  * XXX
  878                  * this shouldn't happen, but if it does, the
  879                  * correct behavior may be to insert the checksum
  880                  * in the appropriate next mbuf in the chain.
  881                  */
  882                 return;
  883         }
  884         *(u_short *)(m->m_data + offset) = csum;
  885 }
  886 
  887 /*
  888  * IP socket option processing.
  889  */
  890 int
  891 ip_ctloutput(struct socket *so, struct sockopt *sopt)
  892 {
  893         struct  inpcb *inp = sotoinpcb(so);
  894         int     error, optval;
  895 
  896         error = optval = 0;
  897         if (sopt->sopt_level != IPPROTO_IP) {
  898                 error = EINVAL;
  899 
  900                 if (sopt->sopt_level == SOL_SOCKET &&
  901                     sopt->sopt_dir == SOPT_SET) {
  902                         switch (sopt->sopt_name) {
  903                         case SO_REUSEADDR:
  904                                 INP_WLOCK(inp);
  905                                 if (IN_MULTICAST(ntohl(inp->inp_laddr.s_addr))) {
  906                                         if ((so->so_options &
  907                                             (SO_REUSEADDR | SO_REUSEPORT)) != 0)
  908                                                 inp->inp_flags2 |= INP_REUSEPORT;
  909                                         else
  910                                                 inp->inp_flags2 &= ~INP_REUSEPORT;
  911                                 }
  912                                 INP_WUNLOCK(inp);
  913                                 error = 0;
  914                                 break;
  915                         case SO_REUSEPORT:
  916                                 INP_WLOCK(inp);
  917                                 if ((so->so_options & SO_REUSEPORT) != 0)
  918                                         inp->inp_flags2 |= INP_REUSEPORT;
  919                                 else
  920                                         inp->inp_flags2 &= ~INP_REUSEPORT;
  921                                 INP_WUNLOCK(inp);
  922                                 error = 0;
  923                                 break;
  924                         case SO_SETFIB:
  925                                 INP_WLOCK(inp);
  926                                 inp->inp_inc.inc_fibnum = so->so_fibnum;
  927                                 INP_WUNLOCK(inp);
  928                                 error = 0;
  929                                 break;
  930                         default:
  931                                 break;
  932                         }
  933                 }
  934                 return (error);
  935         }
  936 
  937         switch (sopt->sopt_dir) {
  938         case SOPT_SET:
  939                 switch (sopt->sopt_name) {
  940                 case IP_OPTIONS:
  941 #ifdef notyet
  942                 case IP_RETOPTS:
  943 #endif
  944                 {
  945                         struct mbuf *m;
  946                         if (sopt->sopt_valsize > MLEN) {
  947                                 error = EMSGSIZE;
  948                                 break;
  949                         }
  950                         MGET(m, sopt->sopt_td ? M_WAIT : M_DONTWAIT, MT_DATA);
  951                         if (m == NULL) {
  952                                 error = ENOBUFS;
  953                                 break;
  954                         }
  955                         m->m_len = sopt->sopt_valsize;
  956                         error = sooptcopyin(sopt, mtod(m, char *), m->m_len,
  957                                             m->m_len);
  958                         if (error) {
  959                                 m_free(m);
  960                                 break;
  961                         }
  962                         INP_WLOCK(inp);
  963                         error = ip_pcbopts(inp, sopt->sopt_name, m);
  964                         INP_WUNLOCK(inp);
  965                         return (error);
  966                 }
  967 
  968                 case IP_BINDANY:
  969                         if (sopt->sopt_td != NULL) {
  970                                 error = priv_check(sopt->sopt_td,
  971                                     PRIV_NETINET_BINDANY);
  972                                 if (error)
  973                                         break;
  974                         }
  975                         /* FALLTHROUGH */
  976                 case IP_TOS:
  977                 case IP_TTL:
  978                 case IP_MINTTL:
  979                 case IP_RECVOPTS:
  980                 case IP_RECVRETOPTS:
  981                 case IP_RECVDSTADDR:
  982                 case IP_RECVTTL:
  983                 case IP_RECVIF:
  984                 case IP_FAITH:
  985                 case IP_ONESBCAST:
  986                 case IP_DONTFRAG:
  987                         error = sooptcopyin(sopt, &optval, sizeof optval,
  988                                             sizeof optval);
  989                         if (error)
  990                                 break;
  991 
  992                         switch (sopt->sopt_name) {
  993                         case IP_TOS:
  994                                 inp->inp_ip_tos = optval;
  995                                 break;
  996 
  997                         case IP_TTL:
  998                                 inp->inp_ip_ttl = optval;
  999                                 break;
 1000 
 1001                         case IP_MINTTL:
 1002                                 if (optval >= 0 && optval <= MAXTTL)
 1003                                         inp->inp_ip_minttl = optval;
 1004                                 else
 1005                                         error = EINVAL;
 1006                                 break;
 1007 
 1008 #define OPTSET(bit) do {                                                \
 1009         INP_WLOCK(inp);                                                 \
 1010         if (optval)                                                     \
 1011                 inp->inp_flags |= bit;                                  \
 1012         else                                                            \
 1013                 inp->inp_flags &= ~bit;                                 \
 1014         INP_WUNLOCK(inp);                                               \
 1015 } while (0)
 1016 
 1017                         case IP_RECVOPTS:
 1018                                 OPTSET(INP_RECVOPTS);
 1019                                 break;
 1020 
 1021                         case IP_RECVRETOPTS:
 1022                                 OPTSET(INP_RECVRETOPTS);
 1023                                 break;
 1024 
 1025                         case IP_RECVDSTADDR:
 1026                                 OPTSET(INP_RECVDSTADDR);
 1027                                 break;
 1028 
 1029                         case IP_RECVTTL:
 1030                                 OPTSET(INP_RECVTTL);
 1031                                 break;
 1032 
 1033                         case IP_RECVIF:
 1034                                 OPTSET(INP_RECVIF);
 1035                                 break;
 1036 
 1037                         case IP_FAITH:
 1038                                 OPTSET(INP_FAITH);
 1039                                 break;
 1040 
 1041                         case IP_ONESBCAST:
 1042                                 OPTSET(INP_ONESBCAST);
 1043                                 break;
 1044                         case IP_DONTFRAG:
 1045                                 OPTSET(INP_DONTFRAG);
 1046                                 break;
 1047                         case IP_BINDANY:
 1048                                 OPTSET(INP_BINDANY);
 1049                                 break;
 1050                         }
 1051                         break;
 1052 #undef OPTSET
 1053 
 1054                 /*
 1055                  * Multicast socket options are processed by the in_mcast
 1056                  * module.
 1057                  */
 1058                 case IP_MULTICAST_IF:
 1059                 case IP_MULTICAST_VIF:
 1060                 case IP_MULTICAST_TTL:
 1061                 case IP_MULTICAST_LOOP:
 1062                 case IP_ADD_MEMBERSHIP:
 1063                 case IP_DROP_MEMBERSHIP:
 1064                 case IP_ADD_SOURCE_MEMBERSHIP:
 1065                 case IP_DROP_SOURCE_MEMBERSHIP:
 1066                 case IP_BLOCK_SOURCE:
 1067                 case IP_UNBLOCK_SOURCE:
 1068                 case IP_MSFILTER:
 1069                 case MCAST_JOIN_GROUP:
 1070                 case MCAST_LEAVE_GROUP:
 1071                 case MCAST_JOIN_SOURCE_GROUP:
 1072                 case MCAST_LEAVE_SOURCE_GROUP:
 1073                 case MCAST_BLOCK_SOURCE:
 1074                 case MCAST_UNBLOCK_SOURCE:
 1075                         error = inp_setmoptions(inp, sopt);
 1076                         break;
 1077 
 1078                 case IP_PORTRANGE:
 1079                         error = sooptcopyin(sopt, &optval, sizeof optval,
 1080                                             sizeof optval);
 1081                         if (error)
 1082                                 break;
 1083 
 1084                         INP_WLOCK(inp);
 1085                         switch (optval) {
 1086                         case IP_PORTRANGE_DEFAULT:
 1087                                 inp->inp_flags &= ~(INP_LOWPORT);
 1088                                 inp->inp_flags &= ~(INP_HIGHPORT);
 1089                                 break;
 1090 
 1091                         case IP_PORTRANGE_HIGH:
 1092                                 inp->inp_flags &= ~(INP_LOWPORT);
 1093                                 inp->inp_flags |= INP_HIGHPORT;
 1094                                 break;
 1095 
 1096                         case IP_PORTRANGE_LOW:
 1097                                 inp->inp_flags &= ~(INP_HIGHPORT);
 1098                                 inp->inp_flags |= INP_LOWPORT;
 1099                                 break;
 1100 
 1101                         default:
 1102                                 error = EINVAL;
 1103                                 break;
 1104                         }
 1105                         INP_WUNLOCK(inp);
 1106                         break;
 1107 
 1108 #ifdef IPSEC
 1109                 case IP_IPSEC_POLICY:
 1110                 {
 1111                         caddr_t req;
 1112                         struct mbuf *m;
 1113 
 1114                         if ((error = soopt_getm(sopt, &m)) != 0) /* XXX */
 1115                                 break;
 1116                         if ((error = soopt_mcopyin(sopt, m)) != 0) /* XXX */
 1117                                 break;
 1118                         req = mtod(m, caddr_t);
 1119                         error = ipsec_set_policy(inp, sopt->sopt_name, req,
 1120                             m->m_len, (sopt->sopt_td != NULL) ?
 1121                             sopt->sopt_td->td_ucred : NULL);
 1122                         m_freem(m);
 1123                         break;
 1124                 }
 1125 #endif /* IPSEC */
 1126 
 1127                 default:
 1128                         error = ENOPROTOOPT;
 1129                         break;
 1130                 }
 1131                 break;
 1132 
 1133         case SOPT_GET:
 1134                 switch (sopt->sopt_name) {
 1135                 case IP_OPTIONS:
 1136                 case IP_RETOPTS:
 1137                         if (inp->inp_options)
 1138                                 error = sooptcopyout(sopt, 
 1139                                                      mtod(inp->inp_options,
 1140                                                           char *),
 1141                                                      inp->inp_options->m_len);
 1142                         else
 1143                                 sopt->sopt_valsize = 0;
 1144                         break;
 1145 
 1146                 case IP_TOS:
 1147                 case IP_TTL:
 1148                 case IP_MINTTL:
 1149                 case IP_RECVOPTS:
 1150                 case IP_RECVRETOPTS:
 1151                 case IP_RECVDSTADDR:
 1152                 case IP_RECVTTL:
 1153                 case IP_RECVIF:
 1154                 case IP_PORTRANGE:
 1155                 case IP_FAITH:
 1156                 case IP_ONESBCAST:
 1157                 case IP_DONTFRAG:
 1158                 case IP_BINDANY:
 1159                         switch (sopt->sopt_name) {
 1160 
 1161                         case IP_TOS:
 1162                                 optval = inp->inp_ip_tos;
 1163                                 break;
 1164 
 1165                         case IP_TTL:
 1166                                 optval = inp->inp_ip_ttl;
 1167                                 break;
 1168 
 1169                         case IP_MINTTL:
 1170                                 optval = inp->inp_ip_minttl;
 1171                                 break;
 1172 
 1173 #define OPTBIT(bit)     (inp->inp_flags & bit ? 1 : 0)
 1174 
 1175                         case IP_RECVOPTS:
 1176                                 optval = OPTBIT(INP_RECVOPTS);
 1177                                 break;
 1178 
 1179                         case IP_RECVRETOPTS:
 1180                                 optval = OPTBIT(INP_RECVRETOPTS);
 1181                                 break;
 1182 
 1183                         case IP_RECVDSTADDR:
 1184                                 optval = OPTBIT(INP_RECVDSTADDR);
 1185                                 break;
 1186 
 1187                         case IP_RECVTTL:
 1188                                 optval = OPTBIT(INP_RECVTTL);
 1189                                 break;
 1190 
 1191                         case IP_RECVIF:
 1192                                 optval = OPTBIT(INP_RECVIF);
 1193                                 break;
 1194 
 1195                         case IP_PORTRANGE:
 1196                                 if (inp->inp_flags & INP_HIGHPORT)
 1197                                         optval = IP_PORTRANGE_HIGH;
 1198                                 else if (inp->inp_flags & INP_LOWPORT)
 1199                                         optval = IP_PORTRANGE_LOW;
 1200                                 else
 1201                                         optval = 0;
 1202                                 break;
 1203 
 1204                         case IP_FAITH:
 1205                                 optval = OPTBIT(INP_FAITH);
 1206                                 break;
 1207 
 1208                         case IP_ONESBCAST:
 1209                                 optval = OPTBIT(INP_ONESBCAST);
 1210                                 break;
 1211                         case IP_DONTFRAG:
 1212                                 optval = OPTBIT(INP_DONTFRAG);
 1213                                 break;
 1214                         case IP_BINDANY:
 1215                                 optval = OPTBIT(INP_BINDANY);
 1216                                 break;
 1217                         }
 1218                         error = sooptcopyout(sopt, &optval, sizeof optval);
 1219                         break;
 1220 
 1221                 /*
 1222                  * Multicast socket options are processed by the in_mcast
 1223                  * module.
 1224                  */
 1225                 case IP_MULTICAST_IF:
 1226                 case IP_MULTICAST_VIF:
 1227                 case IP_MULTICAST_TTL:
 1228                 case IP_MULTICAST_LOOP:
 1229                 case IP_MSFILTER:
 1230                         error = inp_getmoptions(inp, sopt);
 1231                         break;
 1232 
 1233 #ifdef IPSEC
 1234                 case IP_IPSEC_POLICY:
 1235                 {
 1236                         struct mbuf *m = NULL;
 1237                         caddr_t req = NULL;
 1238                         size_t len = 0;
 1239 
 1240                         if (m != 0) {
 1241                                 req = mtod(m, caddr_t);
 1242                                 len = m->m_len;
 1243                         }
 1244                         error = ipsec_get_policy(sotoinpcb(so), req, len, &m);
 1245                         if (error == 0)
 1246                                 error = soopt_mcopyout(sopt, m); /* XXX */
 1247                         if (error == 0)
 1248                                 m_freem(m);
 1249                         break;
 1250                 }
 1251 #endif /* IPSEC */
 1252 
 1253                 default:
 1254                         error = ENOPROTOOPT;
 1255                         break;
 1256                 }
 1257                 break;
 1258         }
 1259         return (error);
 1260 }
 1261 
 1262 /*
 1263  * Routine called from ip_output() to loop back a copy of an IP multicast
 1264  * packet to the input queue of a specified interface.  Note that this
 1265  * calls the output routine of the loopback "driver", but with an interface
 1266  * pointer that might NOT be a loopback interface -- evil, but easier than
 1267  * replicating that code here.
 1268  */
 1269 static void
 1270 ip_mloopback(struct ifnet *ifp, struct mbuf *m, struct sockaddr_in *dst,
 1271     int hlen)
 1272 {
 1273         register struct ip *ip;
 1274         struct mbuf *copym;
 1275 
 1276         /*
 1277          * Make a deep copy of the packet because we're going to
 1278          * modify the pack in order to generate checksums.
 1279          */
 1280         copym = m_dup(m, M_DONTWAIT);
 1281         if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
 1282                 copym = m_pullup(copym, hlen);
 1283         if (copym != NULL) {
 1284                 /* If needed, compute the checksum and mark it as valid. */
 1285                 if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 1286                         in_delayed_cksum(copym);
 1287                         copym->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 1288                         copym->m_pkthdr.csum_flags |=
 1289                             CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
 1290                         copym->m_pkthdr.csum_data = 0xffff;
 1291                 }
 1292                 /*
 1293                  * We don't bother to fragment if the IP length is greater
 1294                  * than the interface's MTU.  Can this possibly matter?
 1295                  */
 1296                 ip = mtod(copym, struct ip *);
 1297                 ip->ip_len = htons(ip->ip_len);
 1298                 ip->ip_off = htons(ip->ip_off);
 1299                 ip->ip_sum = 0;
 1300                 ip->ip_sum = in_cksum(copym, hlen);
 1301 #if 1 /* XXX */
 1302                 if (dst->sin_family != AF_INET) {
 1303                         printf("ip_mloopback: bad address family %d\n",
 1304                                                 dst->sin_family);
 1305                         dst->sin_family = AF_INET;
 1306                 }
 1307 #endif
 1308                 if_simloop(ifp, copym, dst->sin_family, 0);
 1309         }
 1310 }

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