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/10.0/sys/netinet/ip_output.c 260378 2014-01-06 19:14:46Z glebius $");
   34 
   35 #include "opt_ipfw.h"
   36 #include "opt_ipsec.h"
   37 #include "opt_kdtrace.h"
   38 #include "opt_mbuf_stress_test.h"
   39 #include "opt_mpath.h"
   40 #include "opt_route.h"
   41 #include "opt_sctp.h"
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/kernel.h>
   46 #include <sys/malloc.h>
   47 #include <sys/mbuf.h>
   48 #include <sys/priv.h>
   49 #include <sys/proc.h>
   50 #include <sys/protosw.h>
   51 #include <sys/sdt.h>
   52 #include <sys/socket.h>
   53 #include <sys/socketvar.h>
   54 #include <sys/sysctl.h>
   55 #include <sys/ucred.h>
   56 
   57 #include <net/if.h>
   58 #include <net/if_llatbl.h>
   59 #include <net/netisr.h>
   60 #include <net/pfil.h>
   61 #include <net/route.h>
   62 #include <net/flowtable.h>
   63 #ifdef RADIX_MPATH
   64 #include <net/radix_mpath.h>
   65 #endif
   66 #include <net/vnet.h>
   67 
   68 #include <netinet/in.h>
   69 #include <netinet/in_kdtrace.h>
   70 #include <netinet/in_systm.h>
   71 #include <netinet/ip.h>
   72 #include <netinet/in_pcb.h>
   73 #include <netinet/in_var.h>
   74 #include <netinet/ip_var.h>
   75 #include <netinet/ip_options.h>
   76 #ifdef SCTP
   77 #include <netinet/sctp.h>
   78 #include <netinet/sctp_crc32.h>
   79 #endif
   80 
   81 #ifdef IPSEC
   82 #include <netinet/ip_ipsec.h>
   83 #include <netipsec/ipsec.h>
   84 #endif /* IPSEC*/
   85 
   86 #include <machine/in_cksum.h>
   87 
   88 #include <security/mac/mac_framework.h>
   89 
   90 VNET_DEFINE(u_short, ip_id);
   91 
   92 #ifdef MBUF_STRESS_TEST
   93 static int mbuf_frag_size = 0;
   94 SYSCTL_INT(_net_inet_ip, OID_AUTO, mbuf_frag_size, CTLFLAG_RW,
   95         &mbuf_frag_size, 0, "Fragment outgoing mbufs to this size");
   96 #endif
   97 
   98 static void     ip_mloopback
   99         (struct ifnet *, struct mbuf *, struct sockaddr_in *, int);
  100 
  101 
  102 extern int in_mcast_loop;
  103 extern  struct protosw inetsw[];
  104 
  105 /*
  106  * IP output.  The packet in mbuf chain m contains a skeletal IP
  107  * header (with len, off, ttl, proto, tos, src, dst).
  108  * The mbuf chain containing the packet will be freed.
  109  * The mbuf opt, if present, will not be freed.
  110  * If route ro is present and has ro_rt initialized, route lookup would be
  111  * skipped and ro->ro_rt would be used. If ro is present but ro->ro_rt is NULL,
  112  * then result of route lookup is stored in ro->ro_rt.
  113  *
  114  * In the IP forwarding case, the packet will arrive with options already
  115  * inserted, so must have a NULL opt pointer.
  116  */
  117 int
  118 ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro, int flags,
  119     struct ip_moptions *imo, struct inpcb *inp)
  120 {
  121         struct ip *ip;
  122         struct ifnet *ifp = NULL;       /* keep compiler happy */
  123         struct mbuf *m0;
  124         int hlen = sizeof (struct ip);
  125         int mtu;
  126         int n;  /* scratchpad */
  127         int error = 0;
  128         struct sockaddr_in *dst;
  129         const struct sockaddr_in *gw;
  130         struct in_ifaddr *ia;
  131         int isbroadcast;
  132         uint16_t ip_len, ip_off;
  133         struct route iproute;
  134         struct rtentry *rte;    /* cache for ro->ro_rt */
  135         struct in_addr odst;
  136         struct m_tag *fwd_tag = NULL;
  137 #ifdef IPSEC
  138         int no_route_but_check_spd = 0;
  139 #endif
  140         M_ASSERTPKTHDR(m);
  141 
  142         if (inp != NULL) {
  143                 INP_LOCK_ASSERT(inp);
  144                 M_SETFIB(m, inp->inp_inc.inc_fibnum);
  145                 if (inp->inp_flags & (INP_HW_FLOWID|INP_SW_FLOWID)) {
  146                         m->m_pkthdr.flowid = inp->inp_flowid;
  147                         m->m_flags |= M_FLOWID;
  148                 }
  149         }
  150 
  151         if (ro == NULL) {
  152                 ro = &iproute;
  153                 bzero(ro, sizeof (*ro));
  154         }
  155 
  156 #ifdef FLOWTABLE
  157         if (ro->ro_rt == NULL) {
  158                 struct flentry *fle;
  159                         
  160                 /*
  161                  * The flow table returns route entries valid for up to 30
  162                  * seconds; we rely on the remainder of ip_output() taking no
  163                  * longer than that long for the stability of ro_rt. The
  164                  * flow ID assignment must have happened before this point.
  165                  */
  166                 fle = flowtable_lookup_mbuf(V_ip_ft, m, AF_INET);
  167                 if (fle != NULL)
  168                         flow_to_route(fle, ro);
  169         }
  170 #endif
  171 
  172         if (opt) {
  173                 int len = 0;
  174                 m = ip_insertoptions(m, opt, &len);
  175                 if (len != 0)
  176                         hlen = len; /* ip->ip_hl is updated above */
  177         }
  178         ip = mtod(m, struct ip *);
  179         ip_len = ntohs(ip->ip_len);
  180         ip_off = ntohs(ip->ip_off);
  181 
  182         /*
  183          * Fill in IP header.  If we are not allowing fragmentation,
  184          * then the ip_id field is meaningless, but we don't set it
  185          * to zero.  Doing so causes various problems when devices along
  186          * the path (routers, load balancers, firewalls, etc.) illegally
  187          * disable DF on our packet.  Note that a 16-bit counter
  188          * will wrap around in less than 10 seconds at 100 Mbit/s on a
  189          * medium with MTU 1500.  See Steven M. Bellovin, "A Technique
  190          * for Counting NATted Hosts", Proc. IMW'02, available at
  191          * <http://www.cs.columbia.edu/~smb/papers/fnat.pdf>.
  192          */
  193         if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
  194                 ip->ip_v = IPVERSION;
  195                 ip->ip_hl = hlen >> 2;
  196                 ip->ip_id = ip_newid();
  197                 IPSTAT_INC(ips_localout);
  198         } else {
  199                 /* Header already set, fetch hlen from there */
  200                 hlen = ip->ip_hl << 2;
  201         }
  202 
  203         gw = dst = (struct sockaddr_in *)&ro->ro_dst;
  204 again:
  205         ia = NULL;
  206         /*
  207          * If there is a cached route,
  208          * check that it is to the same destination
  209          * and is still up.  If not, free it and try again.
  210          * The address family should also be checked in case of sharing the
  211          * cache with IPv6.
  212          */
  213         rte = ro->ro_rt;
  214         if (rte && ((rte->rt_flags & RTF_UP) == 0 ||
  215                     rte->rt_ifp == NULL ||
  216                     !RT_LINK_IS_UP(rte->rt_ifp) ||
  217                           dst->sin_family != AF_INET ||
  218                           dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
  219                 RO_RTFREE(ro);
  220                 ro->ro_lle = NULL;
  221                 rte = NULL;
  222         }
  223         if (rte == NULL && fwd_tag == NULL) {
  224                 bzero(dst, sizeof(*dst));
  225                 dst->sin_family = AF_INET;
  226                 dst->sin_len = sizeof(*dst);
  227                 dst->sin_addr = ip->ip_dst;
  228         }
  229         /*
  230          * If routing to interface only, short circuit routing lookup.
  231          * The use of an all-ones broadcast address implies this; an
  232          * interface is specified by the broadcast address of an interface,
  233          * or the destination address of a ptp interface.
  234          */
  235         if (flags & IP_SENDONES) {
  236                 if ((ia = ifatoia(ifa_ifwithbroadaddr(sintosa(dst)))) == NULL &&
  237                     (ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL) {
  238                         IPSTAT_INC(ips_noroute);
  239                         error = ENETUNREACH;
  240                         goto bad;
  241                 }
  242                 ip->ip_dst.s_addr = INADDR_BROADCAST;
  243                 dst->sin_addr = ip->ip_dst;
  244                 ifp = ia->ia_ifp;
  245                 ip->ip_ttl = 1;
  246                 isbroadcast = 1;
  247         } else if (flags & IP_ROUTETOIF) {
  248                 if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL &&
  249                     (ia = ifatoia(ifa_ifwithnet(sintosa(dst), 0))) == NULL) {
  250                         IPSTAT_INC(ips_noroute);
  251                         error = ENETUNREACH;
  252                         goto bad;
  253                 }
  254                 ifp = ia->ia_ifp;
  255                 ip->ip_ttl = 1;
  256                 isbroadcast = in_broadcast(dst->sin_addr, ifp);
  257         } else if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) &&
  258             imo != NULL && imo->imo_multicast_ifp != NULL) {
  259                 /*
  260                  * Bypass the normal routing lookup for multicast
  261                  * packets if the interface is specified.
  262                  */
  263                 ifp = imo->imo_multicast_ifp;
  264                 IFP_TO_IA(ifp, ia);
  265                 isbroadcast = 0;        /* fool gcc */
  266         } else {
  267                 /*
  268                  * We want to do any cloning requested by the link layer,
  269                  * as this is probably required in all cases for correct
  270                  * operation (as it is for ARP).
  271                  */
  272                 if (rte == NULL) {
  273 #ifdef RADIX_MPATH
  274                         rtalloc_mpath_fib(ro,
  275                             ntohl(ip->ip_src.s_addr ^ ip->ip_dst.s_addr),
  276                             inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
  277 #else
  278                         in_rtalloc_ign(ro, 0,
  279                             inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
  280 #endif
  281                         rte = ro->ro_rt;
  282                 }
  283                 if (rte == NULL ||
  284                     rte->rt_ifp == NULL ||
  285                     !RT_LINK_IS_UP(rte->rt_ifp)) {
  286 #ifdef IPSEC
  287                         /*
  288                          * There is no route for this packet, but it is
  289                          * possible that a matching SPD entry exists.
  290                          */
  291                         no_route_but_check_spd = 1;
  292                         mtu = 0; /* Silence GCC warning. */
  293                         goto sendit;
  294 #endif
  295                         IPSTAT_INC(ips_noroute);
  296                         error = EHOSTUNREACH;
  297                         goto bad;
  298                 }
  299                 ia = ifatoia(rte->rt_ifa);
  300                 ifa_ref(&ia->ia_ifa);
  301                 ifp = rte->rt_ifp;
  302                 rte->rt_rmx.rmx_pksent++;
  303                 if (rte->rt_flags & RTF_GATEWAY)
  304                         gw = (struct sockaddr_in *)rte->rt_gateway;
  305                 if (rte->rt_flags & RTF_HOST)
  306                         isbroadcast = (rte->rt_flags & RTF_BROADCAST);
  307                 else
  308                         isbroadcast = in_broadcast(gw->sin_addr, ifp);
  309         }
  310         /*
  311          * Calculate MTU.  If we have a route that is up, use that,
  312          * otherwise use the interface's MTU.
  313          */
  314         if (rte != NULL && (rte->rt_flags & (RTF_UP|RTF_HOST))) {
  315                 /*
  316                  * This case can happen if the user changed the MTU
  317                  * of an interface after enabling IP on it.  Because
  318                  * most netifs don't keep track of routes pointing to
  319                  * them, there is no way for one to update all its
  320                  * routes when the MTU is changed.
  321                  */
  322                 if (rte->rt_rmx.rmx_mtu > ifp->if_mtu)
  323                         rte->rt_rmx.rmx_mtu = ifp->if_mtu;
  324                 mtu = rte->rt_rmx.rmx_mtu;
  325         } else {
  326                 mtu = ifp->if_mtu;
  327         }
  328         /* Catch a possible divide by zero later. */
  329         KASSERT(mtu > 0, ("%s: mtu %d <= 0, rte=%p (rt_flags=0x%08x) ifp=%p",
  330             __func__, mtu, rte, (rte != NULL) ? rte->rt_flags : 0, ifp));
  331         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
  332                 m->m_flags |= M_MCAST;
  333                 /*
  334                  * IP destination address is multicast.  Make sure "gw"
  335                  * still points to the address in "ro".  (It may have been
  336                  * changed to point to a gateway address, above.)
  337                  */
  338                 gw = dst;
  339                 /*
  340                  * See if the caller provided any multicast options
  341                  */
  342                 if (imo != NULL) {
  343                         ip->ip_ttl = imo->imo_multicast_ttl;
  344                         if (imo->imo_multicast_vif != -1)
  345                                 ip->ip_src.s_addr =
  346                                     ip_mcast_src ?
  347                                     ip_mcast_src(imo->imo_multicast_vif) :
  348                                     INADDR_ANY;
  349                 } else
  350                         ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
  351                 /*
  352                  * Confirm that the outgoing interface supports multicast.
  353                  */
  354                 if ((imo == NULL) || (imo->imo_multicast_vif == -1)) {
  355                         if ((ifp->if_flags & IFF_MULTICAST) == 0) {
  356                                 IPSTAT_INC(ips_noroute);
  357                                 error = ENETUNREACH;
  358                                 goto bad;
  359                         }
  360                 }
  361                 /*
  362                  * If source address not specified yet, use address
  363                  * of outgoing interface.
  364                  */
  365                 if (ip->ip_src.s_addr == INADDR_ANY) {
  366                         /* Interface may have no addresses. */
  367                         if (ia != NULL)
  368                                 ip->ip_src = IA_SIN(ia)->sin_addr;
  369                 }
  370 
  371                 if ((imo == NULL && in_mcast_loop) ||
  372                     (imo && imo->imo_multicast_loop)) {
  373                         /*
  374                          * Loop back multicast datagram if not expressly
  375                          * forbidden to do so, even if we are not a member
  376                          * of the group; ip_input() will filter it later,
  377                          * thus deferring a hash lookup and mutex acquisition
  378                          * at the expense of a cheap copy using m_copym().
  379                          */
  380                         ip_mloopback(ifp, m, dst, hlen);
  381                 } else {
  382                         /*
  383                          * If we are acting as a multicast router, perform
  384                          * multicast forwarding as if the packet had just
  385                          * arrived on the interface to which we are about
  386                          * to send.  The multicast forwarding function
  387                          * recursively calls this function, using the
  388                          * IP_FORWARDING flag to prevent infinite recursion.
  389                          *
  390                          * Multicasts that are looped back by ip_mloopback(),
  391                          * above, will be forwarded by the ip_input() routine,
  392                          * if necessary.
  393                          */
  394                         if (V_ip_mrouter && (flags & IP_FORWARDING) == 0) {
  395                                 /*
  396                                  * If rsvp daemon is not running, do not
  397                                  * set ip_moptions. This ensures that the packet
  398                                  * is multicast and not just sent down one link
  399                                  * as prescribed by rsvpd.
  400                                  */
  401                                 if (!V_rsvp_on)
  402                                         imo = NULL;
  403                                 if (ip_mforward &&
  404                                     ip_mforward(ip, ifp, m, imo) != 0) {
  405                                         m_freem(m);
  406                                         goto done;
  407                                 }
  408                         }
  409                 }
  410 
  411                 /*
  412                  * Multicasts with a time-to-live of zero may be looped-
  413                  * back, above, but must not be transmitted on a network.
  414                  * Also, multicasts addressed to the loopback interface
  415                  * are not sent -- the above call to ip_mloopback() will
  416                  * loop back a copy. ip_input() will drop the copy if
  417                  * this host does not belong to the destination group on
  418                  * the loopback interface.
  419                  */
  420                 if (ip->ip_ttl == 0 || ifp->if_flags & IFF_LOOPBACK) {
  421                         m_freem(m);
  422                         goto done;
  423                 }
  424 
  425                 goto sendit;
  426         }
  427 
  428         /*
  429          * If the source address is not specified yet, use the address
  430          * of the outoing interface.
  431          */
  432         if (ip->ip_src.s_addr == INADDR_ANY) {
  433                 /* Interface may have no addresses. */
  434                 if (ia != NULL) {
  435                         ip->ip_src = IA_SIN(ia)->sin_addr;
  436                 }
  437         }
  438 
  439         /*
  440          * Verify that we have any chance at all of being able to queue the
  441          * packet or packet fragments, unless ALTQ is enabled on the given
  442          * interface in which case packetdrop should be done by queueing.
  443          */
  444         n = ip_len / mtu + 1; /* how many fragments ? */
  445         if (
  446 #ifdef ALTQ
  447             (!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
  448 #endif /* ALTQ */
  449             (ifp->if_snd.ifq_len + n) >= ifp->if_snd.ifq_maxlen ) {
  450                 error = ENOBUFS;
  451                 IPSTAT_INC(ips_odropped);
  452                 ifp->if_snd.ifq_drops += n;
  453                 goto bad;
  454         }
  455 
  456         /*
  457          * Look for broadcast address and
  458          * verify user is allowed to send
  459          * such a packet.
  460          */
  461         if (isbroadcast) {
  462                 if ((ifp->if_flags & IFF_BROADCAST) == 0) {
  463                         error = EADDRNOTAVAIL;
  464                         goto bad;
  465                 }
  466                 if ((flags & IP_ALLOWBROADCAST) == 0) {
  467                         error = EACCES;
  468                         goto bad;
  469                 }
  470                 /* don't allow broadcast messages to be fragmented */
  471                 if (ip_len > mtu) {
  472                         error = EMSGSIZE;
  473                         goto bad;
  474                 }
  475                 m->m_flags |= M_BCAST;
  476         } else {
  477                 m->m_flags &= ~M_BCAST;
  478         }
  479 
  480 sendit:
  481 #ifdef IPSEC
  482         switch(ip_ipsec_output(&m, inp, &flags, &error)) {
  483         case 1:
  484                 goto bad;
  485         case -1:
  486                 goto done;
  487         case 0:
  488         default:
  489                 break;  /* Continue with packet processing. */
  490         }
  491         /*
  492          * Check if there was a route for this packet; return error if not.
  493          */
  494         if (no_route_but_check_spd) {
  495                 IPSTAT_INC(ips_noroute);
  496                 error = EHOSTUNREACH;
  497                 goto bad;
  498         }
  499         /* Update variables that are affected by ipsec4_output(). */
  500         ip = mtod(m, struct ip *);
  501         hlen = ip->ip_hl << 2;
  502 #endif /* IPSEC */
  503 
  504         /* Jump over all PFIL processing if hooks are not active. */
  505         if (!PFIL_HOOKED(&V_inet_pfil_hook))
  506                 goto passout;
  507 
  508         /* Run through list of hooks for output packets. */
  509         odst.s_addr = ip->ip_dst.s_addr;
  510         error = pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_OUT, inp);
  511         if (error != 0 || m == NULL)
  512                 goto done;
  513 
  514         ip = mtod(m, struct ip *);
  515 
  516         /* See if destination IP address was changed by packet filter. */
  517         if (odst.s_addr != ip->ip_dst.s_addr) {
  518                 m->m_flags |= M_SKIP_FIREWALL;
  519                 /* If destination is now ourself drop to ip_input(). */
  520                 if (in_localip(ip->ip_dst)) {
  521                         m->m_flags |= M_FASTFWD_OURS;
  522                         if (m->m_pkthdr.rcvif == NULL)
  523                                 m->m_pkthdr.rcvif = V_loif;
  524                         if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  525                                 m->m_pkthdr.csum_flags |=
  526                                     CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
  527                                 m->m_pkthdr.csum_data = 0xffff;
  528                         }
  529                         m->m_pkthdr.csum_flags |=
  530                             CSUM_IP_CHECKED | CSUM_IP_VALID;
  531 #ifdef SCTP
  532                         if (m->m_pkthdr.csum_flags & CSUM_SCTP)
  533                                 m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
  534 #endif
  535                         error = netisr_queue(NETISR_IP, m);
  536                         goto done;
  537                 } else {
  538                         if (ia != NULL)
  539                                 ifa_free(&ia->ia_ifa);
  540                         goto again;     /* Redo the routing table lookup. */
  541                 }
  542         }
  543 
  544         /* See if local, if yes, send it to netisr with IP_FASTFWD_OURS. */
  545         if (m->m_flags & M_FASTFWD_OURS) {
  546                 if (m->m_pkthdr.rcvif == NULL)
  547                         m->m_pkthdr.rcvif = V_loif;
  548                 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  549                         m->m_pkthdr.csum_flags |=
  550                             CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
  551                         m->m_pkthdr.csum_data = 0xffff;
  552                 }
  553 #ifdef SCTP
  554                 if (m->m_pkthdr.csum_flags & CSUM_SCTP)
  555                         m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
  556 #endif
  557                 m->m_pkthdr.csum_flags |=
  558                             CSUM_IP_CHECKED | CSUM_IP_VALID;
  559 
  560                 error = netisr_queue(NETISR_IP, m);
  561                 goto done;
  562         }
  563         /* Or forward to some other address? */
  564         if ((m->m_flags & M_IP_NEXTHOP) &&
  565             (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
  566                 bcopy((fwd_tag+1), dst, sizeof(struct sockaddr_in));
  567                 m->m_flags |= M_SKIP_FIREWALL;
  568                 m->m_flags &= ~M_IP_NEXTHOP;
  569                 m_tag_delete(m, fwd_tag);
  570                 if (ia != NULL)
  571                         ifa_free(&ia->ia_ifa);
  572                 goto again;
  573         }
  574 
  575 passout:
  576         /* 127/8 must not appear on wire - RFC1122. */
  577         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
  578             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
  579                 if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
  580                         IPSTAT_INC(ips_badaddr);
  581                         error = EADDRNOTAVAIL;
  582                         goto bad;
  583                 }
  584         }
  585 
  586         m->m_pkthdr.csum_flags |= CSUM_IP;
  587         if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA & ~ifp->if_hwassist) {
  588                 in_delayed_cksum(m);
  589                 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  590         }
  591 #ifdef SCTP
  592         if (m->m_pkthdr.csum_flags & CSUM_SCTP & ~ifp->if_hwassist) {
  593                 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
  594                 m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
  595         }
  596 #endif
  597 
  598         /*
  599          * If small enough for interface, or the interface will take
  600          * care of the fragmentation for us, we can just send directly.
  601          */
  602         if (ip_len <= mtu ||
  603             (m->m_pkthdr.csum_flags & ifp->if_hwassist & CSUM_TSO) != 0 ||
  604             ((ip_off & IP_DF) == 0 && (ifp->if_hwassist & CSUM_FRAGMENT))) {
  605                 ip->ip_sum = 0;
  606                 if (m->m_pkthdr.csum_flags & CSUM_IP & ~ifp->if_hwassist) {
  607                         ip->ip_sum = in_cksum(m, hlen);
  608                         m->m_pkthdr.csum_flags &= ~CSUM_IP;
  609                 }
  610 
  611                 /*
  612                  * Record statistics for this interface address.
  613                  * With CSUM_TSO the byte/packet count will be slightly
  614                  * incorrect because we count the IP+TCP headers only
  615                  * once instead of for every generated packet.
  616                  */
  617                 if (!(flags & IP_FORWARDING) && ia) {
  618                         if (m->m_pkthdr.csum_flags & CSUM_TSO)
  619                                 ia->ia_ifa.if_opackets +=
  620                                     m->m_pkthdr.len / m->m_pkthdr.tso_segsz;
  621                         else
  622                                 ia->ia_ifa.if_opackets++;
  623                         ia->ia_ifa.if_obytes += m->m_pkthdr.len;
  624                 }
  625 #ifdef MBUF_STRESS_TEST
  626                 if (mbuf_frag_size && m->m_pkthdr.len > mbuf_frag_size)
  627                         m = m_fragment(m, M_NOWAIT, mbuf_frag_size);
  628 #endif
  629                 /*
  630                  * Reset layer specific mbuf flags
  631                  * to avoid confusing lower layers.
  632                  */
  633                 m_clrprotoflags(m);
  634                 IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
  635                 error = (*ifp->if_output)(ifp, m,
  636                     (const struct sockaddr *)gw, ro);
  637                 goto done;
  638         }
  639 
  640         /* Balk when DF bit is set or the interface didn't support TSO. */
  641         if ((ip_off & IP_DF) || (m->m_pkthdr.csum_flags & CSUM_TSO)) {
  642                 error = EMSGSIZE;
  643                 IPSTAT_INC(ips_cantfrag);
  644                 goto bad;
  645         }
  646 
  647         /*
  648          * Too large for interface; fragment if possible. If successful,
  649          * on return, m will point to a list of packets to be sent.
  650          */
  651         error = ip_fragment(ip, &m, mtu, ifp->if_hwassist);
  652         if (error)
  653                 goto bad;
  654         for (; m; m = m0) {
  655                 m0 = m->m_nextpkt;
  656                 m->m_nextpkt = 0;
  657                 if (error == 0) {
  658                         /* Record statistics for this interface address. */
  659                         if (ia != NULL) {
  660                                 ia->ia_ifa.if_opackets++;
  661                                 ia->ia_ifa.if_obytes += m->m_pkthdr.len;
  662                         }
  663                         /*
  664                          * Reset layer specific mbuf flags
  665                          * to avoid confusing upper layers.
  666                          */
  667                         m_clrprotoflags(m);
  668 
  669                         IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
  670                         error = (*ifp->if_output)(ifp, m,
  671                             (const struct sockaddr *)gw, ro);
  672                 } else
  673                         m_freem(m);
  674         }
  675 
  676         if (error == 0)
  677                 IPSTAT_INC(ips_fragmented);
  678 
  679 done:
  680         if (ro == &iproute)
  681                 RO_RTFREE(ro);
  682         if (ia != NULL)
  683                 ifa_free(&ia->ia_ifa);
  684         return (error);
  685 bad:
  686         m_freem(m);
  687         goto done;
  688 }
  689 
  690 /*
  691  * Create a chain of fragments which fit the given mtu. m_frag points to the
  692  * mbuf to be fragmented; on return it points to the chain with the fragments.
  693  * Return 0 if no error. If error, m_frag may contain a partially built
  694  * chain of fragments that should be freed by the caller.
  695  *
  696  * if_hwassist_flags is the hw offload capabilities (see if_data.ifi_hwassist)
  697  */
  698 int
  699 ip_fragment(struct ip *ip, struct mbuf **m_frag, int mtu,
  700     u_long if_hwassist_flags)
  701 {
  702         int error = 0;
  703         int hlen = ip->ip_hl << 2;
  704         int len = (mtu - hlen) & ~7;    /* size of payload in each fragment */
  705         int off;
  706         struct mbuf *m0 = *m_frag;      /* the original packet          */
  707         int firstlen;
  708         struct mbuf **mnext;
  709         int nfrags;
  710         uint16_t ip_len, ip_off;
  711 
  712         ip_len = ntohs(ip->ip_len);
  713         ip_off = ntohs(ip->ip_off);
  714 
  715         if (ip_off & IP_DF) {   /* Fragmentation not allowed */
  716                 IPSTAT_INC(ips_cantfrag);
  717                 return EMSGSIZE;
  718         }
  719 
  720         /*
  721          * Must be able to put at least 8 bytes per fragment.
  722          */
  723         if (len < 8)
  724                 return EMSGSIZE;
  725 
  726         /*
  727          * If the interface will not calculate checksums on
  728          * fragmented packets, then do it here.
  729          */
  730         if (m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  731                 in_delayed_cksum(m0);
  732                 m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  733         }
  734 #ifdef SCTP
  735         if (m0->m_pkthdr.csum_flags & CSUM_SCTP) {
  736                 sctp_delayed_cksum(m0, hlen);
  737                 m0->m_pkthdr.csum_flags &= ~CSUM_SCTP;
  738         }
  739 #endif
  740         if (len > PAGE_SIZE) {
  741                 /* 
  742                  * Fragment large datagrams such that each segment 
  743                  * contains a multiple of PAGE_SIZE amount of data, 
  744                  * plus headers. This enables a receiver to perform 
  745                  * page-flipping zero-copy optimizations.
  746                  *
  747                  * XXX When does this help given that sender and receiver
  748                  * could have different page sizes, and also mtu could
  749                  * be less than the receiver's page size ?
  750                  */
  751                 int newlen;
  752                 struct mbuf *m;
  753 
  754                 for (m = m0, off = 0; m && (off+m->m_len) <= mtu; m = m->m_next)
  755                         off += m->m_len;
  756 
  757                 /*
  758                  * firstlen (off - hlen) must be aligned on an 
  759                  * 8-byte boundary
  760                  */
  761                 if (off < hlen)
  762                         goto smart_frag_failure;
  763                 off = ((off - hlen) & ~7) + hlen;
  764                 newlen = (~PAGE_MASK) & mtu;
  765                 if ((newlen + sizeof (struct ip)) > mtu) {
  766                         /* we failed, go back the default */
  767 smart_frag_failure:
  768                         newlen = len;
  769                         off = hlen + len;
  770                 }
  771                 len = newlen;
  772 
  773         } else {
  774                 off = hlen + len;
  775         }
  776 
  777         firstlen = off - hlen;
  778         mnext = &m0->m_nextpkt;         /* pointer to next packet */
  779 
  780         /*
  781          * Loop through length of segment after first fragment,
  782          * make new header and copy data of each part and link onto chain.
  783          * Here, m0 is the original packet, m is the fragment being created.
  784          * The fragments are linked off the m_nextpkt of the original
  785          * packet, which after processing serves as the first fragment.
  786          */
  787         for (nfrags = 1; off < ip_len; off += len, nfrags++) {
  788                 struct ip *mhip;        /* ip header on the fragment */
  789                 struct mbuf *m;
  790                 int mhlen = sizeof (struct ip);
  791 
  792                 m = m_gethdr(M_NOWAIT, MT_DATA);
  793                 if (m == NULL) {
  794                         error = ENOBUFS;
  795                         IPSTAT_INC(ips_odropped);
  796                         goto done;
  797                 }
  798                 m->m_flags |= (m0->m_flags & M_MCAST);
  799                 /*
  800                  * In the first mbuf, leave room for the link header, then
  801                  * copy the original IP header including options. The payload
  802                  * goes into an additional mbuf chain returned by m_copym().
  803                  */
  804                 m->m_data += max_linkhdr;
  805                 mhip = mtod(m, struct ip *);
  806                 *mhip = *ip;
  807                 if (hlen > sizeof (struct ip)) {
  808                         mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
  809                         mhip->ip_v = IPVERSION;
  810                         mhip->ip_hl = mhlen >> 2;
  811                 }
  812                 m->m_len = mhlen;
  813                 /* XXX do we need to add ip_off below ? */
  814                 mhip->ip_off = ((off - hlen) >> 3) + ip_off;
  815                 if (off + len >= ip_len)
  816                         len = ip_len - off;
  817                 else
  818                         mhip->ip_off |= IP_MF;
  819                 mhip->ip_len = htons((u_short)(len + mhlen));
  820                 m->m_next = m_copym(m0, off, len, M_NOWAIT);
  821                 if (m->m_next == NULL) {        /* copy failed */
  822                         m_free(m);
  823                         error = ENOBUFS;        /* ??? */
  824                         IPSTAT_INC(ips_odropped);
  825                         goto done;
  826                 }
  827                 m->m_pkthdr.len = mhlen + len;
  828                 m->m_pkthdr.rcvif = NULL;
  829 #ifdef MAC
  830                 mac_netinet_fragment(m0, m);
  831 #endif
  832                 m->m_pkthdr.csum_flags = m0->m_pkthdr.csum_flags;
  833                 mhip->ip_off = htons(mhip->ip_off);
  834                 mhip->ip_sum = 0;
  835                 if (m->m_pkthdr.csum_flags & CSUM_IP & ~if_hwassist_flags) {
  836                         mhip->ip_sum = in_cksum(m, mhlen);
  837                         m->m_pkthdr.csum_flags &= ~CSUM_IP;
  838                 }
  839                 *mnext = m;
  840                 mnext = &m->m_nextpkt;
  841         }
  842         IPSTAT_ADD(ips_ofragments, nfrags);
  843 
  844         /*
  845          * Update first fragment by trimming what's been copied out
  846          * and updating header.
  847          */
  848         m_adj(m0, hlen + firstlen - ip_len);
  849         m0->m_pkthdr.len = hlen + firstlen;
  850         ip->ip_len = htons((u_short)m0->m_pkthdr.len);
  851         ip->ip_off = htons(ip_off | IP_MF);
  852         ip->ip_sum = 0;
  853         if (m0->m_pkthdr.csum_flags & CSUM_IP & ~if_hwassist_flags) {
  854                 ip->ip_sum = in_cksum(m0, hlen);
  855                 m0->m_pkthdr.csum_flags &= ~CSUM_IP;
  856         }
  857 
  858 done:
  859         *m_frag = m0;
  860         return error;
  861 }
  862 
  863 void
  864 in_delayed_cksum(struct mbuf *m)
  865 {
  866         struct ip *ip;
  867         uint16_t csum, offset, ip_len;
  868 
  869         ip = mtod(m, struct ip *);
  870         offset = ip->ip_hl << 2 ;
  871         ip_len = ntohs(ip->ip_len);
  872         csum = in_cksum_skip(m, ip_len, offset);
  873         if (m->m_pkthdr.csum_flags & CSUM_UDP && csum == 0)
  874                 csum = 0xffff;
  875         offset += m->m_pkthdr.csum_data;        /* checksum offset */
  876 
  877         if (offset + sizeof(u_short) > m->m_len) {
  878                 printf("delayed m_pullup, m->len: %d  off: %d  p: %d\n",
  879                     m->m_len, offset, ip->ip_p);
  880                 /*
  881                  * XXX
  882                  * this shouldn't happen, but if it does, the
  883                  * correct behavior may be to insert the checksum
  884                  * in the appropriate next mbuf in the chain.
  885                  */
  886                 return;
  887         }
  888         *(u_short *)(m->m_data + offset) = csum;
  889 }
  890 
  891 /*
  892  * IP socket option processing.
  893  */
  894 int
  895 ip_ctloutput(struct socket *so, struct sockopt *sopt)
  896 {
  897         struct  inpcb *inp = sotoinpcb(so);
  898         int     error, optval;
  899 
  900         error = optval = 0;
  901         if (sopt->sopt_level != IPPROTO_IP) {
  902                 error = EINVAL;
  903 
  904                 if (sopt->sopt_level == SOL_SOCKET &&
  905                     sopt->sopt_dir == SOPT_SET) {
  906                         switch (sopt->sopt_name) {
  907                         case SO_REUSEADDR:
  908                                 INP_WLOCK(inp);
  909                                 if ((so->so_options & SO_REUSEADDR) != 0)
  910                                         inp->inp_flags2 |= INP_REUSEADDR;
  911                                 else
  912                                         inp->inp_flags2 &= ~INP_REUSEADDR;
  913                                 INP_WUNLOCK(inp);
  914                                 error = 0;
  915                                 break;
  916                         case SO_REUSEPORT:
  917                                 INP_WLOCK(inp);
  918                                 if ((so->so_options & SO_REUSEPORT) != 0)
  919                                         inp->inp_flags2 |= INP_REUSEPORT;
  920                                 else
  921                                         inp->inp_flags2 &= ~INP_REUSEPORT;
  922                                 INP_WUNLOCK(inp);
  923                                 error = 0;
  924                                 break;
  925                         case SO_SETFIB:
  926                                 INP_WLOCK(inp);
  927                                 inp->inp_inc.inc_fibnum = so->so_fibnum;
  928                                 INP_WUNLOCK(inp);
  929                                 error = 0;
  930                                 break;
  931                         default:
  932                                 break;
  933                         }
  934                 }
  935                 return (error);
  936         }
  937 
  938         switch (sopt->sopt_dir) {
  939         case SOPT_SET:
  940                 switch (sopt->sopt_name) {
  941                 case IP_OPTIONS:
  942 #ifdef notyet
  943                 case IP_RETOPTS:
  944 #endif
  945                 {
  946                         struct mbuf *m;
  947                         if (sopt->sopt_valsize > MLEN) {
  948                                 error = EMSGSIZE;
  949                                 break;
  950                         }
  951                         m = m_get(sopt->sopt_td ? M_WAITOK : M_NOWAIT, MT_DATA);
  952                         if (m == NULL) {
  953                                 error = ENOBUFS;
  954                                 break;
  955                         }
  956                         m->m_len = sopt->sopt_valsize;
  957                         error = sooptcopyin(sopt, mtod(m, char *), m->m_len,
  958                                             m->m_len);
  959                         if (error) {
  960                                 m_free(m);
  961                                 break;
  962                         }
  963                         INP_WLOCK(inp);
  964                         error = ip_pcbopts(inp, sopt->sopt_name, m);
  965                         INP_WUNLOCK(inp);
  966                         return (error);
  967                 }
  968 
  969                 case IP_BINDANY:
  970                         if (sopt->sopt_td != NULL) {
  971                                 error = priv_check(sopt->sopt_td,
  972                                     PRIV_NETINET_BINDANY);
  973                                 if (error)
  974                                         break;
  975                         }
  976                         /* FALLTHROUGH */
  977                 case IP_TOS:
  978                 case IP_TTL:
  979                 case IP_MINTTL:
  980                 case IP_RECVOPTS:
  981                 case IP_RECVRETOPTS:
  982                 case IP_RECVDSTADDR:
  983                 case IP_RECVTTL:
  984                 case IP_RECVIF:
  985                 case IP_FAITH:
  986                 case IP_ONESBCAST:
  987                 case IP_DONTFRAG:
  988                 case IP_RECVTOS:
  989                         error = sooptcopyin(sopt, &optval, sizeof optval,
  990                                             sizeof optval);
  991                         if (error)
  992                                 break;
  993 
  994                         switch (sopt->sopt_name) {
  995                         case IP_TOS:
  996                                 inp->inp_ip_tos = optval;
  997                                 break;
  998 
  999                         case IP_TTL:
 1000                                 inp->inp_ip_ttl = optval;
 1001                                 break;
 1002 
 1003                         case IP_MINTTL:
 1004                                 if (optval >= 0 && optval <= MAXTTL)
 1005                                         inp->inp_ip_minttl = optval;
 1006                                 else
 1007                                         error = EINVAL;
 1008                                 break;
 1009 
 1010 #define OPTSET(bit) do {                                                \
 1011         INP_WLOCK(inp);                                                 \
 1012         if (optval)                                                     \
 1013                 inp->inp_flags |= bit;                                  \
 1014         else                                                            \
 1015                 inp->inp_flags &= ~bit;                                 \
 1016         INP_WUNLOCK(inp);                                               \
 1017 } while (0)
 1018 
 1019                         case IP_RECVOPTS:
 1020                                 OPTSET(INP_RECVOPTS);
 1021                                 break;
 1022 
 1023                         case IP_RECVRETOPTS:
 1024                                 OPTSET(INP_RECVRETOPTS);
 1025                                 break;
 1026 
 1027                         case IP_RECVDSTADDR:
 1028                                 OPTSET(INP_RECVDSTADDR);
 1029                                 break;
 1030 
 1031                         case IP_RECVTTL:
 1032                                 OPTSET(INP_RECVTTL);
 1033                                 break;
 1034 
 1035                         case IP_RECVIF:
 1036                                 OPTSET(INP_RECVIF);
 1037                                 break;
 1038 
 1039                         case IP_FAITH:
 1040                                 OPTSET(INP_FAITH);
 1041                                 break;
 1042 
 1043                         case IP_ONESBCAST:
 1044                                 OPTSET(INP_ONESBCAST);
 1045                                 break;
 1046                         case IP_DONTFRAG:
 1047                                 OPTSET(INP_DONTFRAG);
 1048                                 break;
 1049                         case IP_BINDANY:
 1050                                 OPTSET(INP_BINDANY);
 1051                                 break;
 1052                         case IP_RECVTOS:
 1053                                 OPTSET(INP_RECVTOS);
 1054                                 break;
 1055                         }
 1056                         break;
 1057 #undef OPTSET
 1058 
 1059                 /*
 1060                  * Multicast socket options are processed by the in_mcast
 1061                  * module.
 1062                  */
 1063                 case IP_MULTICAST_IF:
 1064                 case IP_MULTICAST_VIF:
 1065                 case IP_MULTICAST_TTL:
 1066                 case IP_MULTICAST_LOOP:
 1067                 case IP_ADD_MEMBERSHIP:
 1068                 case IP_DROP_MEMBERSHIP:
 1069                 case IP_ADD_SOURCE_MEMBERSHIP:
 1070                 case IP_DROP_SOURCE_MEMBERSHIP:
 1071                 case IP_BLOCK_SOURCE:
 1072                 case IP_UNBLOCK_SOURCE:
 1073                 case IP_MSFILTER:
 1074                 case MCAST_JOIN_GROUP:
 1075                 case MCAST_LEAVE_GROUP:
 1076                 case MCAST_JOIN_SOURCE_GROUP:
 1077                 case MCAST_LEAVE_SOURCE_GROUP:
 1078                 case MCAST_BLOCK_SOURCE:
 1079                 case MCAST_UNBLOCK_SOURCE:
 1080                         error = inp_setmoptions(inp, sopt);
 1081                         break;
 1082 
 1083                 case IP_PORTRANGE:
 1084                         error = sooptcopyin(sopt, &optval, sizeof optval,
 1085                                             sizeof optval);
 1086                         if (error)
 1087                                 break;
 1088 
 1089                         INP_WLOCK(inp);
 1090                         switch (optval) {
 1091                         case IP_PORTRANGE_DEFAULT:
 1092                                 inp->inp_flags &= ~(INP_LOWPORT);
 1093                                 inp->inp_flags &= ~(INP_HIGHPORT);
 1094                                 break;
 1095 
 1096                         case IP_PORTRANGE_HIGH:
 1097                                 inp->inp_flags &= ~(INP_LOWPORT);
 1098                                 inp->inp_flags |= INP_HIGHPORT;
 1099                                 break;
 1100 
 1101                         case IP_PORTRANGE_LOW:
 1102                                 inp->inp_flags &= ~(INP_HIGHPORT);
 1103                                 inp->inp_flags |= INP_LOWPORT;
 1104                                 break;
 1105 
 1106                         default:
 1107                                 error = EINVAL;
 1108                                 break;
 1109                         }
 1110                         INP_WUNLOCK(inp);
 1111                         break;
 1112 
 1113 #ifdef IPSEC
 1114                 case IP_IPSEC_POLICY:
 1115                 {
 1116                         caddr_t req;
 1117                         struct mbuf *m;
 1118 
 1119                         if ((error = soopt_getm(sopt, &m)) != 0) /* XXX */
 1120                                 break;
 1121                         if ((error = soopt_mcopyin(sopt, m)) != 0) /* XXX */
 1122                                 break;
 1123                         req = mtod(m, caddr_t);
 1124                         error = ipsec_set_policy(inp, sopt->sopt_name, req,
 1125                             m->m_len, (sopt->sopt_td != NULL) ?
 1126                             sopt->sopt_td->td_ucred : NULL);
 1127                         m_freem(m);
 1128                         break;
 1129                 }
 1130 #endif /* IPSEC */
 1131 
 1132                 default:
 1133                         error = ENOPROTOOPT;
 1134                         break;
 1135                 }
 1136                 break;
 1137 
 1138         case SOPT_GET:
 1139                 switch (sopt->sopt_name) {
 1140                 case IP_OPTIONS:
 1141                 case IP_RETOPTS:
 1142                         if (inp->inp_options)
 1143                                 error = sooptcopyout(sopt, 
 1144                                                      mtod(inp->inp_options,
 1145                                                           char *),
 1146                                                      inp->inp_options->m_len);
 1147                         else
 1148                                 sopt->sopt_valsize = 0;
 1149                         break;
 1150 
 1151                 case IP_TOS:
 1152                 case IP_TTL:
 1153                 case IP_MINTTL:
 1154                 case IP_RECVOPTS:
 1155                 case IP_RECVRETOPTS:
 1156                 case IP_RECVDSTADDR:
 1157                 case IP_RECVTTL:
 1158                 case IP_RECVIF:
 1159                 case IP_PORTRANGE:
 1160                 case IP_FAITH:
 1161                 case IP_ONESBCAST:
 1162                 case IP_DONTFRAG:
 1163                 case IP_BINDANY:
 1164                 case IP_RECVTOS:
 1165                         switch (sopt->sopt_name) {
 1166 
 1167                         case IP_TOS:
 1168                                 optval = inp->inp_ip_tos;
 1169                                 break;
 1170 
 1171                         case IP_TTL:
 1172                                 optval = inp->inp_ip_ttl;
 1173                                 break;
 1174 
 1175                         case IP_MINTTL:
 1176                                 optval = inp->inp_ip_minttl;
 1177                                 break;
 1178 
 1179 #define OPTBIT(bit)     (inp->inp_flags & bit ? 1 : 0)
 1180 
 1181                         case IP_RECVOPTS:
 1182                                 optval = OPTBIT(INP_RECVOPTS);
 1183                                 break;
 1184 
 1185                         case IP_RECVRETOPTS:
 1186                                 optval = OPTBIT(INP_RECVRETOPTS);
 1187                                 break;
 1188 
 1189                         case IP_RECVDSTADDR:
 1190                                 optval = OPTBIT(INP_RECVDSTADDR);
 1191                                 break;
 1192 
 1193                         case IP_RECVTTL:
 1194                                 optval = OPTBIT(INP_RECVTTL);
 1195                                 break;
 1196 
 1197                         case IP_RECVIF:
 1198                                 optval = OPTBIT(INP_RECVIF);
 1199                                 break;
 1200 
 1201                         case IP_PORTRANGE:
 1202                                 if (inp->inp_flags & INP_HIGHPORT)
 1203                                         optval = IP_PORTRANGE_HIGH;
 1204                                 else if (inp->inp_flags & INP_LOWPORT)
 1205                                         optval = IP_PORTRANGE_LOW;
 1206                                 else
 1207                                         optval = 0;
 1208                                 break;
 1209 
 1210                         case IP_FAITH:
 1211                                 optval = OPTBIT(INP_FAITH);
 1212                                 break;
 1213 
 1214                         case IP_ONESBCAST:
 1215                                 optval = OPTBIT(INP_ONESBCAST);
 1216                                 break;
 1217                         case IP_DONTFRAG:
 1218                                 optval = OPTBIT(INP_DONTFRAG);
 1219                                 break;
 1220                         case IP_BINDANY:
 1221                                 optval = OPTBIT(INP_BINDANY);
 1222                                 break;
 1223                         case IP_RECVTOS:
 1224                                 optval = OPTBIT(INP_RECVTOS);
 1225                                 break;
 1226                         }
 1227                         error = sooptcopyout(sopt, &optval, sizeof optval);
 1228                         break;
 1229 
 1230                 /*
 1231                  * Multicast socket options are processed by the in_mcast
 1232                  * module.
 1233                  */
 1234                 case IP_MULTICAST_IF:
 1235                 case IP_MULTICAST_VIF:
 1236                 case IP_MULTICAST_TTL:
 1237                 case IP_MULTICAST_LOOP:
 1238                 case IP_MSFILTER:
 1239                         error = inp_getmoptions(inp, sopt);
 1240                         break;
 1241 
 1242 #ifdef IPSEC
 1243                 case IP_IPSEC_POLICY:
 1244                 {
 1245                         struct mbuf *m = NULL;
 1246                         caddr_t req = NULL;
 1247                         size_t len = 0;
 1248 
 1249                         if (m != 0) {
 1250                                 req = mtod(m, caddr_t);
 1251                                 len = m->m_len;
 1252                         }
 1253                         error = ipsec_get_policy(sotoinpcb(so), req, len, &m);
 1254                         if (error == 0)
 1255                                 error = soopt_mcopyout(sopt, m); /* XXX */
 1256                         if (error == 0)
 1257                                 m_freem(m);
 1258                         break;
 1259                 }
 1260 #endif /* IPSEC */
 1261 
 1262                 default:
 1263                         error = ENOPROTOOPT;
 1264                         break;
 1265                 }
 1266                 break;
 1267         }
 1268         return (error);
 1269 }
 1270 
 1271 /*
 1272  * Routine called from ip_output() to loop back a copy of an IP multicast
 1273  * packet to the input queue of a specified interface.  Note that this
 1274  * calls the output routine of the loopback "driver", but with an interface
 1275  * pointer that might NOT be a loopback interface -- evil, but easier than
 1276  * replicating that code here.
 1277  */
 1278 static void
 1279 ip_mloopback(struct ifnet *ifp, struct mbuf *m, struct sockaddr_in *dst,
 1280     int hlen)
 1281 {
 1282         register struct ip *ip;
 1283         struct mbuf *copym;
 1284 
 1285         /*
 1286          * Make a deep copy of the packet because we're going to
 1287          * modify the pack in order to generate checksums.
 1288          */
 1289         copym = m_dup(m, M_NOWAIT);
 1290         if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
 1291                 copym = m_pullup(copym, hlen);
 1292         if (copym != NULL) {
 1293                 /* If needed, compute the checksum and mark it as valid. */
 1294                 if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 1295                         in_delayed_cksum(copym);
 1296                         copym->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 1297                         copym->m_pkthdr.csum_flags |=
 1298                             CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
 1299                         copym->m_pkthdr.csum_data = 0xffff;
 1300                 }
 1301                 /*
 1302                  * We don't bother to fragment if the IP length is greater
 1303                  * than the interface's MTU.  Can this possibly matter?
 1304                  */
 1305                 ip = mtod(copym, struct ip *);
 1306                 ip->ip_sum = 0;
 1307                 ip->ip_sum = in_cksum(copym, hlen);
 1308 #if 1 /* XXX */
 1309                 if (dst->sin_family != AF_INET) {
 1310                         printf("ip_mloopback: bad address family %d\n",
 1311                                                 dst->sin_family);
 1312                         dst->sin_family = AF_INET;
 1313                 }
 1314 #endif
 1315                 if_simloop(ifp, copym, dst->sin_family, 0);
 1316         }
 1317 }

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