[mpls-linux-general] I need some help to read the codes related with MPLS patches

[<jj...@dr...>]

I've looked at the code, and i think that the binding point of mpls_outpu=
t() is in route.c

After patching mpls codes, in ./net/ipv4/route.c

void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
{
      struct fib_info *fi =3D res->fi;
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=A1=A6
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#ifdef CONFIG_MPLS
      /*  JLEU: we need to do this here because both
      * ip_route_output_slow() and ip_route_output_slow()
      * us this to finish the next hop calculations
      */
      if(res->proto_data[AUX_PROTO_DATA_MPLS]) {
          struct mpls_out_info *moi;
          int i;
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          MPLS_DEBUG(("rt_set_nexthop: adding label to dst\n"));
          MPLS_DEBUG(("rt_set_nexthop: before - mtu =3D %d\n",
            rt->u.dst.pmtu));
          rt->u.dst.output =3D mpls_output;    /* HERE */
          rt->u.dst.dst_proto_data[AUX_PROTO_DATA_MPLS] =3D=20
            res->proto_data[AUX_PROTO_DATA_MPLS];
          moi =3D res->proto_data[AUX_PROTO_DATA_MPLS];
mpls_again:
          for(i=3D0;i<moi->moi_instruction_length;i++) {
            switch(moi->moi_instruction[i].mi_opcode) {
                case MPLS_OP_FWD:
                  moi =3D (struct mpls_out_info*)
                    moi->moi_instruction[i].mi_data;
                  goto mpls_again;
                  break;
                case MPLS_OP_PUSH:
                  rt->u.dst.pmtu -=3D 4;
                  break;
            }
          }
          MPLS_DEBUG(("rt_set_nexthop: after - mtu =3D %d\n",
            rt->u.dst.pmtu));
      }
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=A1=A6
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}
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If res->proto_data[AUX_PROTO_DATA_MPLS] have a value (not zero)
then the output related function is binded with mpls_output()
so the function is invoked.
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But I still try to find work that describes the structures or methods of =
MPLS in Linux .=20
Is there anyone who know this? I hope to learn from him or her.
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Especially, I want to know the semantics of proto_data[AUX_PROTO_DATA_MPL=
S].
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Thanks, in advance.
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B.E.
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Kiyoung Jung
-------------------------------------------------------
Ki Young Jung (jj...@ic...)
Information and Communications University(ICU)
Broadband Network Laboratory(http://bnlab.icu.ac.kr)
58-4 Hwaam-dong, Yusong-gu, Taejon, 305-732, KOREA
Tel)+82-42-866-6182, 016-370-1751 Fax)+82-42-866-6110=20
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