msg_out.c

《嵌入式网络系统设计-基于Atmel ARM7 系列》这个本书的光盘资料

  snmp_asn1_enc_length_cnt(rhl->pdulen, &rhl->pdulenlen);
  tot_len += 1 + rhl->pdulenlen;

  rhl->comlen = m_stat->com_strlen;
  snmp_asn1_enc_length_cnt(rhl->comlen, &rhl->comlenlen);
  tot_len += 1 + rhl->comlenlen + rhl->comlen;

  snmp_asn1_enc_s32t_cnt(snmp_version, &rhl->verlen);
  snmp_asn1_enc_length_cnt(rhl->verlen, &rhl->verlenlen);
  tot_len += 1 + rhl->verlen + rhl->verlenlen;

  rhl->seqlen = tot_len;
  snmp_asn1_enc_length_cnt(rhl->seqlen, &rhl->seqlenlen);
  tot_len += 1 + rhl->seqlenlen;

  return tot_len;
}

/**
 * Sums trap header field lengths from tail to head and
 * returns trap_header_lengths for second encoding pass.
 *
 * @param vb_len varbind-list length
 * @param thl points to returned header lengths
 * @return the required lenght for encoding the trap header
 */
static u16_t
snmp_trap_header_sum(struct snmp_msg_trap *m_trap, u16_t vb_len)
{
  u16_t tot_len;
  struct snmp_trap_header_lengths *thl;

  thl = &m_trap->thl;
  tot_len = vb_len;

  snmp_asn1_enc_u32t_cnt(m_trap->ts, &thl->tslen);
  snmp_asn1_enc_length_cnt(thl->tslen, &thl->tslenlen);
  tot_len += 1 + thl->tslen + thl->tslenlen;

  snmp_asn1_enc_s32t_cnt(m_trap->spc_trap, &thl->strplen);
  snmp_asn1_enc_length_cnt(thl->strplen, &thl->strplenlen);
  tot_len += 1 + thl->strplen + thl->strplenlen;

  snmp_asn1_enc_s32t_cnt(m_trap->gen_trap, &thl->gtrplen);
  snmp_asn1_enc_length_cnt(thl->gtrplen, &thl->gtrplenlen);
  tot_len += 1 + thl->gtrplen + thl->gtrplenlen;

  thl->aaddrlen = 4;
  snmp_asn1_enc_length_cnt(thl->aaddrlen, &thl->aaddrlenlen);
  tot_len += 1 + thl->aaddrlen + thl->aaddrlenlen;

  snmp_asn1_enc_oid_cnt(m_trap->enterprise->len, &m_trap->enterprise->id[0], &thl->eidlen);
  snmp_asn1_enc_length_cnt(thl->eidlen, &thl->eidlenlen);
  tot_len += 1 + thl->eidlen + thl->eidlenlen;

  thl->pdulen = tot_len;
  snmp_asn1_enc_length_cnt(thl->pdulen, &thl->pdulenlen);
  tot_len += 1 + thl->pdulenlen;

  thl->comlen = sizeof(snmp_publiccommunity) - 1;
  snmp_asn1_enc_length_cnt(thl->comlen, &thl->comlenlen);
  tot_len += 1 + thl->comlenlen + thl->comlen;

  snmp_asn1_enc_s32t_cnt(snmp_version, &thl->verlen);
  snmp_asn1_enc_length_cnt(thl->verlen, &thl->verlenlen);
  tot_len += 1 + thl->verlen + thl->verlenlen;

  thl->seqlen = tot_len;
  snmp_asn1_enc_length_cnt(thl->seqlen, &thl->seqlenlen);
  tot_len += 1 + thl->seqlenlen;

  return tot_len;
}

/**
 * Sums varbind lengths from tail to head and
 * annotates lengths in varbind for second encoding pass.
 *
 * @param root points to the root of the variable binding list
 * @return the required lenght for encoding the variable bindings
 */
static u16_t
snmp_varbind_list_sum(struct snmp_varbind_root *root)
{
  struct snmp_varbind *vb;
  u32_t *uint_ptr;
  s32_t *sint_ptr;
  u16_t tot_len;

  tot_len = 0;
  vb = root->tail;
  while ( vb != NULL )
  {
    /* encoded value lenght depends on type */
    switch (vb->value_type)
    {
      case (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG):
        sint_ptr = vb->value;
        snmp_asn1_enc_s32t_cnt(*sint_ptr, &vb->vlen);
        break;
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_COUNTER):
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_GAUGE):
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_TIMETICKS):
        uint_ptr = vb->value;
        snmp_asn1_enc_u32t_cnt(*uint_ptr, &vb->vlen);
        break;
      case (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_OC_STR):
      case (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_NUL):
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_IPADDR):
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_OPAQUE):
        vb->vlen = vb->value_len;
        break;
      case (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_OBJ_ID):
        sint_ptr = vb->value;
        snmp_asn1_enc_oid_cnt(vb->value_len / sizeof(s32_t), sint_ptr, &vb->vlen);
        break;
      default:
        /* unsupported type */
        vb->vlen = 0;
        break;
    };
    /* encoding length of value length field */
    snmp_asn1_enc_length_cnt(vb->vlen, &vb->vlenlen);
    snmp_asn1_enc_oid_cnt(vb->ident_len, vb->ident, &vb->olen);
    snmp_asn1_enc_length_cnt(vb->olen, &vb->olenlen);

    vb->seqlen = 1 + vb->vlenlen + vb->vlen;
    vb->seqlen += 1 + vb->olenlen + vb->olen;
    snmp_asn1_enc_length_cnt(vb->seqlen, &vb->seqlenlen);

    /* varbind seq */
    tot_len += 1 + vb->seqlenlen + vb->seqlen;

    vb = vb->prev;
  }

  /* varbind-list seq */
  root->seqlen = tot_len;
  snmp_asn1_enc_length_cnt(root->seqlen, &root->seqlenlen);
  tot_len += 1 + root->seqlenlen;

  return tot_len;
}

/**
 * Encodes response header from head to tail.
 */
static u16_t
snmp_resp_header_enc(struct snmp_msg_pstat *m_stat, struct pbuf *p)
{
  u16_t ofs;

  ofs = 0;
  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_CONSTR | SNMP_ASN1_SEQ));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_stat->rhl.seqlen);
  ofs += m_stat->rhl.seqlenlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_stat->rhl.verlen);
  ofs += m_stat->rhl.verlenlen;
  snmp_asn1_enc_s32t(p, ofs, m_stat->rhl.verlen, snmp_version);
  ofs += m_stat->rhl.verlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_OC_STR));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_stat->rhl.comlen);
  ofs += m_stat->rhl.comlenlen;
  snmp_asn1_enc_raw(p, ofs, m_stat->rhl.comlen, m_stat->community);
  ofs += m_stat->rhl.comlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_CONTXT | SNMP_ASN1_CONSTR | SNMP_ASN1_PDU_GET_RESP));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_stat->rhl.pdulen);
  ofs += m_stat->rhl.pdulenlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_stat->rhl.ridlen);
  ofs += m_stat->rhl.ridlenlen;
  snmp_asn1_enc_s32t(p, ofs, m_stat->rhl.ridlen, m_stat->rid);
  ofs += m_stat->rhl.ridlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_stat->rhl.errstatlen);
  ofs += m_stat->rhl.errstatlenlen;
  snmp_asn1_enc_s32t(p, ofs, m_stat->rhl.errstatlen, m_stat->error_status);
  ofs += m_stat->rhl.errstatlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_stat->rhl.erridxlen);
  ofs += m_stat->rhl.erridxlenlen;
  snmp_asn1_enc_s32t(p, ofs, m_stat->rhl.erridxlen, m_stat->error_index);
  ofs += m_stat->rhl.erridxlen;

  return ofs;
}

/**
 * Encodes trap header from head to tail.
 */
static u16_t
snmp_trap_header_enc(struct snmp_msg_trap *m_trap, struct pbuf *p)
{
  u16_t ofs;

  ofs = 0;
  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_CONSTR | SNMP_ASN1_SEQ));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.seqlen);
  ofs += m_trap->thl.seqlenlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.verlen);
  ofs += m_trap->thl.verlenlen;
  snmp_asn1_enc_s32t(p, ofs, m_trap->thl.verlen, snmp_version);
  ofs += m_trap->thl.verlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_OC_STR));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.comlen);
  ofs += m_trap->thl.comlenlen;
  snmp_asn1_enc_raw(p, ofs, m_trap->thl.comlen, (u8_t *)&snmp_publiccommunity[0]);
  ofs += m_trap->thl.comlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_CONTXT | SNMP_ASN1_CONSTR | SNMP_ASN1_PDU_TRAP));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.pdulen);
  ofs += m_trap->thl.pdulenlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_OBJ_ID));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.eidlen);
  ofs += m_trap->thl.eidlenlen;
  snmp_asn1_enc_oid(p, ofs, m_trap->enterprise->len, &m_trap->enterprise->id[0]);
  ofs += m_trap->thl.eidlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_IPADDR));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.aaddrlen);
  ofs += m_trap->thl.aaddrlenlen;
  snmp_asn1_enc_raw(p, ofs, m_trap->thl.aaddrlen, &m_trap->sip_raw[0]);
  ofs += m_trap->thl.aaddrlen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.gtrplen);
  ofs += m_trap->thl.gtrplenlen;
  snmp_asn1_enc_u32t(p, ofs, m_trap->thl.gtrplen, m_trap->gen_trap);
  ofs += m_trap->thl.gtrplen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.strplen);
  ofs += m_trap->thl.strplenlen;
  snmp_asn1_enc_u32t(p, ofs, m_trap->thl.strplen, m_trap->spc_trap);
  ofs += m_trap->thl.strplen;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_TIMETICKS));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, m_trap->thl.tslen);
  ofs += m_trap->thl.tslenlen;
  snmp_asn1_enc_u32t(p, ofs, m_trap->thl.tslen, m_trap->ts);
  ofs += m_trap->thl.tslen;

  return ofs;
}

/**
 * Encodes varbind list from head to tail.
 */
static u16_t
snmp_varbind_list_enc(struct snmp_varbind_root *root, struct pbuf *p, u16_t ofs)
{
  struct snmp_varbind *vb;
  s32_t *sint_ptr;
  u32_t *uint_ptr;
  u8_t *raw_ptr;

  snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_CONSTR | SNMP_ASN1_SEQ));
  ofs += 1;
  snmp_asn1_enc_length(p, ofs, root->seqlen);
  ofs += root->seqlenlen;

  vb = root->head;
  while ( vb != NULL )
  {
    snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_CONSTR | SNMP_ASN1_SEQ));
    ofs += 1;
    snmp_asn1_enc_length(p, ofs, vb->seqlen);
    ofs += vb->seqlenlen;

    snmp_asn1_enc_type(p, ofs, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_OBJ_ID));
    ofs += 1;
    snmp_asn1_enc_length(p, ofs, vb->olen);
    ofs += vb->olenlen;
    snmp_asn1_enc_oid(p, ofs, vb->ident_len, &vb->ident[0]);
    ofs += vb->olen;

    snmp_asn1_enc_type(p, ofs, vb->value_type);
    ofs += 1;
    snmp_asn1_enc_length(p, ofs, vb->vlen);
    ofs += vb->vlenlen;

    switch (vb->value_type)
    {
      case (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG):
        sint_ptr = vb->value;
        snmp_asn1_enc_s32t(p, ofs, vb->vlen, *sint_ptr);
        break;
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_COUNTER):
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_GAUGE):
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_TIMETICKS):
        uint_ptr = vb->value;
        snmp_asn1_enc_u32t(p, ofs, vb->vlen, *uint_ptr);
        break;
      case (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_OC_STR):
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_IPADDR):
      case (SNMP_ASN1_APPLIC | SNMP_ASN1_PRIMIT | SNMP_ASN1_OPAQUE):
        raw_ptr = vb->value;
        snmp_asn1_enc_raw(p, ofs, vb->vlen, raw_ptr);
        break;
      case (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_NUL):
        break;
      case (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_OBJ_ID):
        sint_ptr = vb->value;
        snmp_asn1_enc_oid(p, ofs, vb->value_len / sizeof(s32_t), sint_ptr);
        break;
      default:
        /* unsupported type */
        break;
    };
    ofs += vb->vlen;
    vb = vb->next;
  }
  return ofs;
}

#endif /* LWIP_SNMP */