ldp_buf.c

实现了MPLS中的标签分发协议（LDP 3036 )的基本功能

  int max_mesg_size;
  int encodedSize = 0;
  u_short type = 0;
  int mesgSize = 0;

  MPLS_ASSERT(b);

  LDP_ENTER(g->user_data, "ldp_decode_one_mesg");

  if (msg->header.pduLength > (b->size - 4)) {
    LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
      LDP_TRACE_FLAG_PACKET, "Buffer too small. Decoding failed\n");
    LDP_EXIT(g->user_data, "ldp_decode_one_mesg - failure");
    return MPLS_FAILURE;
  }

  max_mesg_size = b->current_size;

  /* found the message type */
  memcpy((u_char *) & type, b->current, 2);
  type = ntohs(type) & 0x7fff;  /* ignore the U bit for now */

  LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV, LDP_TRACE_FLAG_PACKET,
    "Found type %x\n", type);

  switch (type) {
    case MPLS_INIT_MSGTYPE:
      {
        MPLS_MSGPTR(Init) = &msg->u.init;
        encodedSize = Mpls_decodeLdpInitMsg(MPLS_MSGPARAM(Init),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_INIT, MPLS_TRACE_STATE_RECV,
          ldp_buf_dump(g->user_data, b, encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_INIT, "decodedSize for Init msg = %d\n", encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV, LDP_TRACE_FLAG_INIT,
          printHeader(g->user_data, &msg->header),
          printInitMsg(g->user_data, MPLS_MSGPARAM(Init)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    case MPLS_NOT_MSGTYPE:
      {
        MPLS_MSGPTR(Notif) = &msg->u.notif;
        encodedSize = Mpls_decodeLdpNotMsg(MPLS_MSGPARAM(Notif),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_NOTIF, MPLS_TRACE_STATE_RECV,
          ldp_buf_dump(g->user_data, b,
            (encodedSize < 0) ? max_mesg_size : encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV, LDP_TRACE_FLAG_NOTIF,
          "decodedSize for Notif msg = %d\n", encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_NOTIF,
          printHeader(g->user_data, &msg->header),
          printNotMsg(g->user_data, MPLS_MSGPARAM(Notif)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    case MPLS_KEEPAL_MSGTYPE:
      {
        MPLS_MSGPTR(KeepAl) = &msg->u.keep;
        encodedSize = Mpls_decodeLdpKeepAliveMsg(MPLS_MSGPARAM(KeepAl),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_PERIODIC,
          MPLS_TRACE_STATE_RECV, ldp_buf_dump(g->user_data, b, encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_PERIODIC,
          "decodedSize for KeepAlive msg = %d\n", encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_PERIODIC,
          printHeader(g->user_data, &msg->header),
          printKeepAliveMsg(g->user_data, MPLS_MSGPARAM(KeepAl)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    case MPLS_HELLO_MSGTYPE:
      {
        MPLS_MSGPTR(Hello) = &msg->u.hello;
        encodedSize = Mpls_decodeLdpHelloMsg(MPLS_MSGPARAM(Hello),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_PERIODIC,
          MPLS_TRACE_STATE_RECV, ldp_buf_dump(g->user_data, b, encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_PERIODIC, "decodedSize for Hello msg = %d\n",
          encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_PERIODIC,
          printHeader(g->user_data, &msg->header),
          printHelloMsg(g->user_data, MPLS_MSGPARAM(Hello)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    case MPLS_LBLREQ_MSGTYPE:
      {
        MPLS_MSGPTR(LblReq) = &msg->u.request;
        encodedSize = Mpls_decodeLdpLblReqMsg(MPLS_MSGPARAM(LblReq),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_LABEL, MPLS_TRACE_STATE_RECV,
          ldp_buf_dump(g->user_data, b, encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_LABEL, "decodedSize for Req msg = %d\n", encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_LABEL,
          printHeader(g->user_data, &msg->header),
          printLlbReqMsg(g->user_data, MPLS_MSGPARAM(LblReq)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    case MPLS_LBLMAP_MSGTYPE:
      {
        MPLS_MSGPTR(LblMap) = &msg->u.map;
        encodedSize = Mpls_decodeLdpLblMapMsg(MPLS_MSGPARAM(LblMap),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_LABEL, MPLS_TRACE_STATE_RECV,
          ldp_buf_dump(g->user_data, b, encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_LABEL, "decodedSize for Map msg = %d\n", encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_LABEL,
          printHeader(g->user_data, &msg->header),
          printLlbMapMsg(g->user_data, MPLS_MSGPARAM(LblMap)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    case MPLS_ADDR_MSGTYPE:
    case MPLS_ADDRWITH_MSGTYPE:
      {
        MPLS_MSGPTR(Adr) = &msg->u.addr;
        encodedSize = Mpls_decodeLdpAdrMsg(MPLS_MSGPARAM(Adr),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_ADDRESS,
          MPLS_TRACE_STATE_RECV, ldp_buf_dump(g->user_data, b, encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_ADDRESS, "decodedSize for Adr msg = %d\n",
          encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_ADDRESS,
          printHeader(g->user_data, &msg->header),
          printAddressMsg(g->user_data, MPLS_MSGPARAM(Adr)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    case MPLS_LBLWITH_MSGTYPE:
    case MPLS_LBLREL_MSGTYPE:
      {
        MPLS_MSGPTR(Lbl_W_R_) = &msg->u.release;
        encodedSize = Mpls_decodeLdpLbl_W_R_Msg(MPLS_MSGPARAM(Lbl_W_R_),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_LABEL, MPLS_TRACE_STATE_RECV,
          ldp_buf_dump(g->user_data, b, encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_LABEL,
          "decodedSize for Lbl Release/Mapping msg = %d\n", encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_LABEL,
          printHeader(g->user_data, &msg->header),
          printLbl_W_R_Msg(g->user_data, MPLS_MSGPARAM(Lbl_W_R_)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    case MPLS_LBLABORT_MSGTYPE:
      {
        MPLS_MSGPTR(LblAbort) = &msg->u.abort;
        encodedSize = Mpls_decodeLdpLblAbortMsg(MPLS_MSGPARAM(LblAbort),
          b->current, max_mesg_size);
        LDP_DUMP_PKT(g->user_data, LDP_TRACE_FLAG_LABEL, MPLS_TRACE_STATE_RECV,
          ldp_buf_dump(g->user_data, b, encodedSize));
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_LABEL, "decodedSize for Abort msg = %d\n",
          encodedSize);
        if (encodedSize < 0) {
          goto ldp_decode_one_mesg;
        }
        LDP_TRACE_PKT(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_LABEL,
          printHeader(g->user_data, &msg->header),
          printLlbAbortMsg(g->user_data, MPLS_MSGPARAM(LblAbort)));
        b->current += encodedSize;
        mesgSize += encodedSize;
        break;
      }
    default:
      {
        LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
          LDP_TRACE_FLAG_PACKET, "Unknown message type = %x\n", type);
        goto ldp_decode_one_mesg;
      }
  }                             /* switch */

  LDP_TRACE_LOG(g->user_data, MPLS_TRACE_STATE_RECV,
    LDP_TRACE_FLAG_PACKET, "Mesg size: %d (%d)\n", mesgSize, b->size);

  b->current_size -= mesgSize;

  LDP_EXIT(g->user_data, "ldp_decode_one_mesg");
  return MPLS_SUCCESS;

ldp_decode_one_mesg:

  LDP_EXIT(g->user_data, "ldp_decode_one_mesg - failure");
  return MPLS_FAILURE;
}