mib_structs.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

            return (struct mib_node*)en;
          }
          else
          {
            /* found it, proceed to child */
            ident_len--;
            ident++;
            ext_level++;
          }
        }
        else
        {
          /* search failed */
          LWIP_DEBUGF(SNMP_MIB_DEBUG,("en search failed *ident==%"S32_F"\n",*ident));
          return NULL;
        }
      }
      else
      {
        /* search failed, short object identifier (nosuchname) */
        LWIP_DEBUGF(SNMP_MIB_DEBUG,("en search failed, short object identifier\n"));
        return NULL;
      }
    }
    else if (node_type == MIB_NODE_SC)
    {
      mib_scalar_node *sn;

      sn = (mib_scalar_node *)node;
      if ((ident_len == 1) && (*ident == 0))
      {
        np->ident_len = ident_len;
        np->ident = ident;
        return (struct mib_node*)sn;
      }
      else
      {
        /* search failed, short object identifier (nosuchname) */
        LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed, invalid object identifier length\n"));
        return NULL;
      }
    }
    else
    {
      /* unknown node_type */
      LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed node_type %"U16_F" unkown\n",(u16_t)node_type));
      return NULL;
    }
  }
  /* done, found nothing */
  LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed node==%p\n",(void*)node));
  return NULL;
}

/**
 * Test table for presence of at least one table entry.
 */
static u8_t
empty_table(struct mib_node *node)
{
  u8_t node_type;
  u8_t empty = 0;

  if (node != NULL)
  {
    node_type = node->node_type;
    if (node_type == MIB_NODE_LR)
    {
      struct mib_list_rootnode *lrn;
      lrn = (struct mib_list_rootnode *)node;
      if ((lrn->count == 0) || (lrn->head == NULL))
      {
        empty = 1;
      }
    }
    else if ((node_type == MIB_NODE_AR) || (node_type == MIB_NODE_RA))
    {
      struct mib_array_node *an;
      an = (struct mib_array_node *)node;
      if ((an->maxlength == 0) || (an->nptr == NULL))
      {
        empty = 1;
      }
    }
    else if (node_type == MIB_NODE_EX)
    {
      struct mib_external_node *en;
      en = (struct mib_external_node *)node;
      if (en->tree_levels == 0)
      {
        empty = 1;
      }
    }
  }
  return empty;
}

/**
 * Tree expansion.
 */
struct mib_node *
snmp_expand_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct snmp_obj_id *oidret)
{
  u8_t node_type, ext_level, climb_tree;

  ext_level = 0;
  /* reset node stack */
  node_stack_cnt = 0;
  while (node != NULL)
  {
    climb_tree = 0;
    node_type = node->node_type;
    if ((node_type == MIB_NODE_AR) || (node_type == MIB_NODE_RA))
    {
      struct mib_array_node *an;
      u16_t i;

      /* array node (internal ROM or RAM, fixed length) */
      an = (struct mib_array_node *)node;
      if (ident_len > 0)
      {
        i = 0;
        while ((i < an->maxlength) && (an->objid[i] < *ident))
        {
          i++;
        }
        if (i < an->maxlength)
        {
          LWIP_DEBUGF(SNMP_MIB_DEBUG,("an->objid[%"U16_F"]==%"S32_F" *ident==%"S32_F"\n",i,an->objid[i],*ident));
          /* add identifier to oidret */
          oidret->id[oidret->len] = an->objid[i];
          (oidret->len)++;

          if (an->nptr[i] == NULL)
          {
            LWIP_DEBUGF(SNMP_MIB_DEBUG,("leaf node\n"));
            /* leaf node (e.g. in a fixed size table) */
            if (an->objid[i] > *ident)
            {
              return (struct mib_node*)an;
            }
            else if ((i + 1) < an->maxlength)
            {
              /* an->objid[i] == *ident */
              (oidret->len)--;
              oidret->id[oidret->len] = an->objid[i + 1];
              (oidret->len)++;
              return (struct mib_node*)an;
            }
            else
            {
              /* (i + 1) == an->maxlength */
              (oidret->len)--;
              climb_tree = 1;
            }
          }
          else
          {
            u8_t j;
            struct nse cur_node;

            LWIP_DEBUGF(SNMP_MIB_DEBUG,("non-leaf node\n"));
            /* non-leaf, store right child ptr and id */
            j = i + 1;
            while ((j < an->maxlength) && (empty_table(an->nptr[j])))
            {
              j++;
            }
            if (j < an->maxlength)
            {
              cur_node.r_ptr = an->nptr[j];
              cur_node.r_id = an->objid[j];
              cur_node.r_nl = 0;
            }
            else
            {
              cur_node.r_ptr = NULL;
            }
            push_node(&cur_node);
            if (an->objid[i] == *ident)
            {
              ident_len--;
              ident++;
            }
            else
            {
              /* an->objid[i] < *ident */
              ident_len = 0;
            }
            /* follow next child pointer */
            node = an->nptr[i];
          }
        }
        else
        {
          /* i == an->maxlength */
          climb_tree = 1;
        }
      }
      else
      {
        u8_t j;
        /* ident_len == 0, complete with leftmost '.thing' */
        j = 0;
        while ((j < an->maxlength) && empty_table(an->nptr[j]))
        {
          j++;
        }
        if (j < an->maxlength)
        {
          LWIP_DEBUGF(SNMP_MIB_DEBUG,("left an->objid[j]==%"S32_F"\n",an->objid[j]));
          oidret->id[oidret->len] = an->objid[j];
          (oidret->len)++;
          if (an->nptr[j] == NULL)
          {
            /* leaf node */
            return (struct mib_node*)an;
          }
          else
          {
            /* no leaf, continue */
            node = an->nptr[j];
          }
        }
        else
        {
          /* j == an->maxlength */
          climb_tree = 1;
        }
      }
    }
    else if(node_type == MIB_NODE_LR)
    {
      struct mib_list_rootnode *lrn;
      struct mib_list_node *ln;

      /* list root node (internal 'RAM', variable length) */
      lrn = (struct mib_list_rootnode *)node;
      if (ident_len > 0)
      {
        ln = lrn->head;
        /* iterate over list, head to tail */
        while ((ln != NULL) && (ln->objid < *ident))
        {
          ln = ln->next;
        }
        if (ln != NULL)
        {
          LWIP_DEBUGF(SNMP_MIB_DEBUG,("ln->objid==%"S32_F" *ident==%"S32_F"\n",ln->objid,*ident));
          oidret->id[oidret->len] = ln->objid;
          (oidret->len)++;
          if (ln->nptr == NULL)
          {
            /* leaf node */
            if (ln->objid > *ident)
            {
              return (struct mib_node*)lrn;
            }
            else if (ln->next != NULL)
            {
              /* ln->objid == *ident */
              (oidret->len)--;
              oidret->id[oidret->len] = ln->next->objid;
              (oidret->len)++;
              return (struct mib_node*)lrn;
            }
            else
            {
              /* ln->next == NULL */
              (oidret->len)--;
              climb_tree = 1;
            }
          }
          else
          {
            struct mib_list_node *jn;
            struct nse cur_node;

            /* non-leaf, store right child ptr and id */
            jn = ln->next;
            while ((jn != NULL) && empty_table(jn->nptr))
            {
              jn = jn->next;
            }
            if (jn != NULL)
            {
              cur_node.r_ptr = jn->nptr;
              cur_node.r_id = jn->objid;
              cur_node.r_nl = 0;
            }
            else
            {
              cur_node.r_ptr = NULL;
            }
            push_node(&cur_node);
            if (ln->objid == *ident)
            {
              ident_len--;
              ident++;
            }
            else
            {
              /* ln->objid < *ident */
              ident_len = 0;
            }
            /* follow next child pointer */
            node = ln->nptr;
          }

        }
        else
        {
          /* ln == NULL */
          climb_tree = 1;
        }
      }
      else
      {
        struct mib_list_node *jn;
        /* ident_len == 0, complete with leftmost '.thing' */
        jn = lrn->head;
        while ((jn != NULL) && empty_table(jn->nptr))
        {
          jn = jn->next;
        }
        if (jn != NULL)
        {
          LWIP_DEBUGF(SNMP_MIB_DEBUG,("left jn->objid==%"S32_F"\n",jn->objid));
          oidret->id[oidret->len] = jn->objid;
          (oidret->len)++;
          if (jn->nptr == NULL)
          {
            /* leaf node */
            LWIP_DEBUGF(SNMP_MIB_DEBUG,("jn->nptr == NULL\n"));
            return (struct mib_node*)lrn;
          }
          else
          {
            /* no leaf, continue */
            node = jn->nptr;
          }
        }
        else
        {
          /* jn == NULL */
          climb_tree = 1;
        }
      }
    }
    else if(node_type == MIB_NODE_EX)
    {
      struct mib_external_node *en;
      s32_t ex_id;

      /* external node (addressing and access via functions) */
      en = (struct mib_external_node *)node;
      if (ident_len > 0)
      {
        u16_t i, len;

        i = 0;
        len = en->level_length(en->addr_inf,ext_level);
        while ((i < len) && (en->ident_cmp(en->addr_inf,ext_level,i,*ident) < 0))
        {
          i++;
        }
        if (i < len)
        {
          /* add identifier to oidret */
          en->get_objid(en->addr_inf,ext_level,i,&ex_id);
          LWIP_DEBUGF(SNMP_MIB_DEBUG,("en->objid[%"U16_F"]==%"S32_F" *ident==%"S32_F"\n",i,ex_id,*ident));
          oidret->id[oidret->len] = ex_id;
          (oidret->len)++;

          if ((ext_level + 1) == en->tree_levels)
          {
            LWIP_DEBUGF(SNMP_MIB_DEBUG,("leaf node\n"));
            /* leaf node */
            if (ex_id > *ident)
            {
              return (struct mib_node*)en;
            }
            else if ((i + 1) < len)
            {
              /* ex_id == *ident */
              en->get_objid(en->addr_inf,ext_level,i + 1,&ex_id);
              (oidret->len)--;
              oidret->id[oidret->len] = ex_id;
              (oidret->len)++;
              return (struct mib_node*)en;
            }
            else
            {
              /* (i + 1) == len */
              (oidret->len)--;
              climb_tree = 1;
            }
          }
          else
          {
            u8_t j;
            struct nse cur_node;

            LWIP_DEBUGF(SNMP_MIB_DEBUG,("non-leaf node\n"));
            /* non-leaf, store right child ptr and id */
            j = i + 1;
            if (j < len)
            {
              /* right node is the current external node */
              cur_node.r_ptr = node;
              en->get_objid(en->addr_inf,ext_level,j,&cur_node.r_id);
              cur_node.r_nl = ext_level + 1;
            }
            else
            {
              cur_node.r_ptr = NULL;
            }
            push_node(&cur_node);
            if (en->ident_cmp(en->addr_inf,ext_level,i,*ident) == 0)
            {
              ident_len--;
              ident++;
            }
            else
            {
              /* external id < *ident */
              ident_len = 0;
            }
            /* proceed to child */
            ext_level++;
          }
        }
        else
        {
          /* i == len (en->level_len()) */
          climb_tree = 1;
        }
      }
      else
      {
        /* ident_len == 0, complete with leftmost '.thing' */
        en->get_objid(en->addr_inf,ext_level,0,&ex_id);
        LWIP_DEBUGF(SNMP_MIB_DEBUG,("left en->objid==%"S32_F"\n",ex_id));
        oidret->id[oidret->len] = ex_id;
        (oidret->len)++;
        if ((ext_level + 1) == en->tree_levels)
        {
          /* leaf node */
          LWIP_DEBUGF(SNMP_MIB_DEBUG,("(ext_level + 1) == en->tree_levels\n"));
          return (struct mib_node*)en;
        }
        else
        {
          /* no leaf, proceed to child */
          ext_level++;
        }
      }
    }
    else if(node_type == MIB_NODE_SC)
    {
      mib_scalar_node *sn;

      /* scalar node  */
      sn = (mib_scalar_node *)node;
      if (ident_len > 0)
      {
        /* at .0 */
        climb_tree = 1;
      }
      else
      {
        /* ident_len == 0, complete object identifier */
        oidret->id[oidret->len] = 0;
        (oidret->len)++;
        /* leaf node */
        LWIP_DEBUGF(SNMP_MIB_DEBUG,("completed scalar leaf\n"));
        return (struct mib_node*)sn;
      }
    }
    else
    {
      /* unknown/unhandled node_type */
      LWIP_DEBUGF(SNMP_MIB_DEBUG,("expand failed node_type %"U16_F" unkown\n",(u16_t)node_type));
      return NULL;
    }

    if (climb_tree)
    {
      struct nse child;

      /* find right child ptr */
      child.r_ptr = NULL;
      child.r_id = 0;
      child.r_nl = 0;
      while ((node_stack_cnt > 0) && (child.r_ptr == NULL))
      {
        pop_node(&child);
        /* trim returned oid */
        (oidret->len)--;
      }
      if (child.r_ptr != NULL)
      {
        /* incoming ident is useless beyond this point */
        ident_len = 0;
        oidret->id[oidret->len] = child.r_id;
        oidret->len++;
        node = child.r_ptr;
        ext_level = child.r_nl;
      }
      else
      {
        /* tree ends here ... */
        LWIP_DEBUGF(SNMP_MIB_DEBUG,("expand failed, tree ends here\n"));
        return NULL;
      }
    }
  }
  /* done, found nothing */
  LWIP_DEBUGF(SNMP_MIB_DEBUG,("expand failed node==%p\n",(void*)node));
  return NULL;
}

/**
 * Test object identifier for the iso.org.dod.internet prefix.
 *
 * @param ident_len the length of the supplied object identifier
 * @param ident points to the array of sub identifiers
 * @return 1 if it matches, 0 otherwise
 */
u8_t
snmp_iso_prefix_tst(u8_t ident_len, s32_t *ident)
{
  if ((ident_len > 3) &&
      (ident[0] == 1) && (ident[1] == 3) &&
      (ident[2] == 6) && (ident[3] == 1))
  {
    return 1;
  }
  else
  {
    return 0;
  }
}

/**
 * Expands object identifier to the iso.org.dod.internet
 * prefix for use in getnext operation.
 *
 * @param ident_len the length of the supplied object identifier
 * @param ident points to the array of sub identifiers
 * @param oidret points to returned expanded object identifier
 * @return 1 if it matches, 0 otherwise
 *
 * @note ident_len 0 is allowed, expanding to the first known object id!!
 */
u8_t
snmp_iso_prefix_expand(u8_t ident_len, s32_t *ident, struct snmp_obj_id *oidret)
{
  const s32_t *prefix_ptr;
  s32_t *ret_ptr;
  u8_t i;

  i = 0;
  prefix_ptr = &prefix[0];
  ret_ptr = &oidret->id[0];
  ident_len = ((ident_len < 4)?ident_len:4);
  while ((i < ident_len) && ((*ident) <= (*prefix_ptr)))
  {
    *ret_ptr++ = *prefix_ptr++;
    ident++;
    i++;
  }
  if (i == ident_len)
  {
    /* match, complete missing bits */
    while (i < 4)
    {
      *ret_ptr++ = *prefix_ptr++;
      i++;
    }
    oidret->len = i;
    return 1;
  }
  else
  {
    /* i != ident_len */
    return 0;
  }
}

#endif /* LWIP_SNMP */