FreeBSD/Linux Kernel Cross Reference
sys/netatalk/ddp_output.c

     /*
      * Copyright (c) 1990,1991 Regents of The University of Michigan.
      * All Rights Reserved.
      *
      * Permission to use, copy, modify, and distribute this software and
      * its documentation for any purpose and without fee is hereby granted,
      * provided that the above copyright notice appears in all copies and
      * that both that copyright notice and this permission notice appear
      * in supporting documentation, and that the name of The University
     * of Michigan not be used in advertising or publicity pertaining to
     * distribution of the software without specific, written prior
     * permission. This software is supplied as is without expressed or
     * implied warranties of any kind.
     *
     *      Research Systems Unix Group
     *      The University of Michigan
     *      c/o Mike Clark
     *      535 W. William Street
     *      Ann Arbor, Michigan
     *      +1-313-763-0525
     *      netatalk@itd.umich.edu
     */
    
    #include <sys/types.h>
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/mbuf.h>
    #include <sys/socket.h>
    #include <sys/errno.h>
    #include <sys/syslog.h>
    
    #include <net/if.h>
    #include <net/route.h>
    
    #include <netinet/in.h>
    #undef s_net
    #include <netinet/if_ether.h>
    
    #include <netatalk/at.h>
    #include <netatalk/at_var.h>
    #include <netatalk/endian.h>
    #include <netatalk/ddp.h>
    #include <netatalk/ddp_var.h>
    #include <netatalk/at_extern.h>
    
    int     ddp_cksum = 1;
    
    int
    ddp_output( struct ddpcb *ddp, struct mbuf *m)
    {
        struct ddpehdr      *deh;
    
        M_PREPEND( m, sizeof( struct ddpehdr ), M_WAIT );
    
        deh = mtod( m, struct ddpehdr *);
        deh->deh_pad = 0;
        deh->deh_hops = 0;
    
        deh->deh_len = m->m_pkthdr.len;
    
        deh->deh_dnet = ddp->ddp_fsat.sat_addr.s_net;
        deh->deh_dnode = ddp->ddp_fsat.sat_addr.s_node;
        deh->deh_dport = ddp->ddp_fsat.sat_port;
        deh->deh_snet = ddp->ddp_lsat.sat_addr.s_net;
        deh->deh_snode = ddp->ddp_lsat.sat_addr.s_node;
        deh->deh_sport = ddp->ddp_lsat.sat_port;
    
        /*
         * The checksum calculation is done after all of the other bytes have
         * been filled in.
         */
        if ( ddp_cksum ) {
            deh->deh_sum = at_cksum( m, sizeof( int ));
        } else {
            deh->deh_sum = 0;
        }
        deh->deh_bytes = htonl( deh->deh_bytes );
    
        return( ddp_route( m, &ddp->ddp_route ));
    }
    
    u_short
    at_cksum( struct mbuf *m, int skip)
    {
        u_char      *data, *end;
        u_long      cksum = 0;
    
        for (; m; m = m->m_next ) {
            for ( data = mtod( m, u_char * ), end = data + m->m_len; data < end;
                    data++ ) {
                if ( skip ) {
                    skip--;
                    continue;
                }
                cksum = ( cksum + *data ) << 1;
                if ( cksum & 0x00010000 ) {
                    cksum++;
                }
                cksum &= 0x0000ffff;
           }
       }
   
       if ( cksum == 0 ) {
           cksum = 0x0000ffff;
       }
       return( (u_short)cksum );
   }
   
   int
   ddp_route( struct mbuf *m, struct route *ro)
   {
       struct sockaddr_at  gate;
       struct elaphdr      *elh;
       struct mbuf         *m0;
       struct at_ifaddr    *aa = NULL;
       struct ifnet        *ifp = NULL;
       u_short             net;
   
       /*
        * if we have a route, find the ifa that refers to this route.
        * I.e The ifa used to get to the gateway.
        */
       if ( (ro->ro_rt == NULL)
       || ( ro->ro_rt->rt_ifa == NULL )
       || ( (ifp = ro->ro_rt->rt_ifa->ifa_ifp) == NULL )) {
           rtalloc(ro);
       }
       if ( (ro->ro_rt != NULL)
       && ( ro->ro_rt->rt_ifa )
       && ( ifp = ro->ro_rt->rt_ifa->ifa_ifp )) {
           net = ntohs(satosat(ro->ro_rt->rt_gateway)->sat_addr.s_net);
           for ( aa = at_ifaddr; aa; aa = aa->aa_next ) {
               if (((net == 0) || (aa->aa_ifp == ifp)) &&
                       net >= ntohs( aa->aa_firstnet ) &&
                       net <= ntohs( aa->aa_lastnet )) {
                   break;
               }
           }
       } else {
           m_freem( m );
           return( EINVAL );
       }
   
       if ( aa == NULL ) {
   printf( "ddp_route: oops\n" );
           m_freem( m );
           return( EINVAL );
       }
   
       /*
        * if the destination address is on a directly attached node use that,
        * else use the official gateway.
        */
       if ( ntohs( satosat( &ro->ro_dst )->sat_addr.s_net ) >=
               ntohs( aa->aa_firstnet ) &&
               ntohs( satosat( &ro->ro_dst )->sat_addr.s_net ) <=
               ntohs( aa->aa_lastnet )) {
           gate = *satosat( &ro->ro_dst );
       } else {
           gate = *satosat( ro->ro_rt->rt_gateway );
       }
   
       /*
        * There are several places in the kernel where data is added to
        * an mbuf without ensuring that the mbuf pointer is aligned.
        * This is bad for transition routing, since phase 1 and phase 2
        * packets end up poorly aligned due to the three byte elap header.
        */
       if ( !(aa->aa_flags & AFA_PHASE2) ) {
           MGET( m0, M_WAIT, MT_HEADER );
           if ( m0 == 0 ) {
               m_freem( m );
               printf("ddp_route: no buffers\n");
               return( ENOBUFS );
           }
           m0->m_next = m;
           /* XXX perhaps we ought to align the header? */
           m0->m_len = SZ_ELAPHDR;
           m = m0;
   
           elh = mtod( m, struct elaphdr *);
           elh->el_snode = satosat( &aa->aa_addr )->sat_addr.s_node;
           elh->el_type = ELAP_DDPEXTEND;
           elh->el_dnode = gate.sat_addr.s_node;
       }
       ro->ro_rt->rt_use++;
   
       return((*ifp->if_output)( ifp,
           m, (struct sockaddr *)&gate, NULL)); /* XXX */
   }

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