Uma implementação de LDAP em VDM++

1. LDAP em VDM++
Pedro Pereira Ulisses Costa
M´todos Formais em Engenharia de Software
e
12 de Fevereiro de 2009
Pedro Pereira, Ulisses Costa LDAP em VDM++

2. Sum´rio
a
1 LDAP
O que ´ o LDAP e a DIT
e
Estrutura do LDAP
Propriedades do LDAP
2 VDM
DIT - Tree? & Forest
Servidor
3 Opera¸˜es do Servidor
co
Pedro Pereira, Ulisses Costa LDAP em VDM++

3. Sum´rio
a
1 LDAP
O que ´ o LDAP e a DIT
e
Estrutura do LDAP
Propriedades do LDAP
2 VDM
DIT - Tree? & Forest
Servidor
3 Opera¸˜es do Servidor
co
Pedro Pereira, Ulisses Costa LDAP em VDM++

4. LDAP
LDAP vs DAP - Lightweight porque opera em TCP/IP
LDAP ´ pelo menos uma DIT
e
Uma directoria ´ uma maneira de organizar informa¸˜o
e ca
complexa, tornando f´cil a sua pesquisa.
a
Pedro Pereira, Ulisses Costa LDAP em VDM++

5. Sum´rio
a
1 LDAP
O que ´ o LDAP e a DIT
e
Estrutura do LDAP
Propriedades do LDAP
2 VDM
DIT - Tree? & Forest
Servidor
3 Opera¸˜es do Servidor
co
Pedro Pereira, Ulisses Costa LDAP em VDM++

6. Estrutura da DIT
Fun¸˜o da DIT
ca
Guardar a hierarquia
Composta por entradas
Entradas s˜o instˆncias de ObjectClass
a a
ObjectClass’s podem ter atributos
Atributos relacionam a informa¸˜o
ca
Pedro Pereira, Ulisses Costa LDAP em VDM++

7. Estrutura das entradas
Contˆm uma instˆncia de ObjectClass
e a
Atributos obrigat´rios da ObjectClass
o
Um DN (Distinguished Name))
´
Unico em toda a ´rvore
a
Um RDN (Relative Distinguished Name)
´
Unico entre irm˜os
a
Pedro Pereira, Ulisses Costa LDAP em VDM++

8. Sum´rio
a
1 LDAP
O que ´ o LDAP e a DIT
e
Estrutura do LDAP
Propriedades do LDAP
2 VDM
DIT - Tree? & Forest
Servidor
3 Opera¸˜es do Servidor
co
Pedro Pereira, Ulisses Costa LDAP em VDM++

9. Propriedades do LDAP
Floresta de DIT’s
DN’s s˜o unicos na DIT
a´
Um DN ´: O DN do antecessor e o seu RDN
e
Cada atributo tem pares de (identificador,valor)
Pedro Pereira, Ulisses Costa LDAP em VDM++

10. Sum´rio
a
1 LDAP
O que ´ o LDAP e a DIT
e
Estrutura do LDAP
Propriedades do LDAP
2 VDM
DIT - Tree? & Forest
Servidor
3 Opera¸˜es do Servidor
co
Pedro Pereira, Ulisses Costa LDAP em VDM++

11. Sum´rio
a
1 LDAP
O que ´ o LDAP e a DIT
e
Estrutura do LDAP
Propriedades do LDAP
2 VDM
DIT - Tree? & Forest
Servidor
3 Opera¸˜es do Servidor
co
Pedro Pereira, Ulisses Costa LDAP em VDM++

12. DIT - Tree?
Grafo ac´
ıclico e ligado (uma ra´
ız)
The root of the DIT is a DSA-specific Entry (DSE) and not
part of any naming context
Pedro Pereira, Ulisses Costa LDAP em VDM++

13. DIT - Forest
Grafo ac´
ıclico e n˜o ligado (m´ltiplas ra´
a u ızes)
Pedro Pereira, Ulisses Costa LDAP em VDM++

14. Sum´rio
a
1 LDAP
O que ´ o LDAP e a DIT
e
Estrutura do LDAP
Propriedades do LDAP
2 VDM
DIT - Tree? & Forest
Servidor
3 Opera¸˜es do Servidor
co
Pedro Pereira, Ulisses Costa LDAP em VDM++

15. Servidor Estrutura
class Server
types
public String = seq of char ;
public OName = String ;
public AName = String ;
public Value = String ;
public ObjClass :: must : set of AName
may : set of AName ;
instance variables
-- entradas existentes
private entries : map nat1 to Entry ;
-- hierarquia das entradas
private dit : map nat1 to set of nat1 ;
-- objectos definidos
private def_objs : map OName to ObjClass ;
-- atributos definidos
private def_attrs : set of AName ;
inv ServerINV () ;
Pedro Pereira, Ulisses Costa LDAP em VDM++

16. Servidor Invariantes
The root of the DIT is a DSA-specific Entry (DSE) and not part of any naming
context;
Entries have names: one or more attribute values from the entry form its relative
distinguished name (RDN), which MUST be unique among all its siblings;
The concatenation of the relative distinguished names of the sequence of entries
from a particular entry to an immediate subordinate of the root of the tree
forms that entry’s Distinguished Name (DN), which is unique in the tree;
Each entry MUST have an objectClass attribute which specifies the object
classes of that entry ;
Servers MUST NOT permit clients to add attributes to an entry unless those
attributes are permitted by the object class definitions, the schema controlling
that entry ;
Entries consist of a set of attributes;
An attribute is a type with one or more associated values and is identified by a
short descriptive name (...);
Schema is the collection of attribute type definitions, object class definitions and
other information (...);
Pedro Pereira, Ulisses Costa LDAP em VDM++

17. Servidor Invariantes
public ServerINV : () == > bool
ServerINV () ==
(
return (
-- dit aciclica
( not exists e in set dom dit & e in set Tra nsi tive Clo sur e ( e ) ) and
-- todos os elementos que existem estao na dit
( forall e in set ( dom dit union rng dit ) & e in set dom entries ) and
-- objectos apenas contem atributos definidos
( forall o in set rng def_objs & ( forall a in set ( o . must union o . may
) & a in set def_attrs ) ) and
-- dn unico entre todos os elementos da floresta
( forall e1 , e2 in set rng entries & e1 . GetDN () <> e2 . GetDN () ) and
-- dn do pai contido no do filho
( forall p in set dom dit & ( forall c in set Tr ans itiv eCl osu re ( p ) & (
elems entries ( c ) . GetDN () ) subset ( elems entries ( p ) . GetDN () ) ) )
and
-- rdn unico entre irmaos
( forall p in set dom dit & ( forall c1 , c2 in set dit ( p ) & entries ( c1 ) .
GetRDN () <> entries ( c2 ) . GetRDN () ) ) and
-- rdn faz parte do dn
( forall e in set rng entries & e . GetRDN () in set elems e . GetDN () ) and
-- rdn composto por um atributo
( forall e in set rng entries & e . GetRDN () in set dom e . GetAttrs () ) ) ) ;
Pedro Pereira, Ulisses Costa LDAP em VDM++

18. Sum´rio
a
1 LDAP
O que ´ o LDAP e a DIT
e
Estrutura do LDAP
Propriedades do LDAP
2 VDM
DIT - Tree? & Forest
Servidor
3 Opera¸˜es do Servidor
co
Pedro Pereira, Ulisses Costa LDAP em VDM++

19. Servidor Opera¸oes
c˜
CRUD
Create Read Update Delete
Add Entry
Del Entry
Modify DN
Search Entry
Search Attributes
Pedro Pereira, Ulisses Costa LDAP em VDM++

20. Modify DN
public ModDN : seq of AName * AName == > ()
ModDN ( old_dn , new_rdn ) ==
(
dcl new_dn : seq of AName := [];
dcl pos : nat1 := len old_dn - 1;
dcl e : nat1 := GetID ( old_dn ) ;
for i = 1 to pos do
new_dn := new_dn ^ [ old_dn ( i ) ];
new_dn := new_dn ^ [ new_rdn ];
entries ( e ) . SetDN ( new_dn ) ;
for all c in set Tra nsi tiv eCl osur e ( e ) do
(
new_dn := [];
for i = 1 to ( len entries ( c ) . GetDN () ) do
if i = pos
then new_dn := new_dn ^ [ new_rdn ]
else new_dn := new_dn ^ entries ( c ) . GetDN () ( i ) ;
entries ( c ) . SetDN ( new_dn ) ;
);
)
pre ( exists i in set dom entries & entries ( i ) . GetDN () = old_dn )
post ( exists i in set dom entries & forall c in set Tran sit ive Clo sure ( i ) &
new_rdn in set elems entries ( i ) . GetDN () and new_rdn in set elems entries ( c )
. GetDN () ) ;
Pedro Pereira, Ulisses Costa LDAP em VDM++

21. GetID
public GetID : seq of AName == > nat
GetID ( dn ) ==
(
for all i in set dom entries do
if entries ( i ) . GetDN () = dn
then return i ;
return 0;
)
post ( not exists i in set dom entries & entries ( i ) . GetDN () = dn = > RESULT = 0 )
or
( exists i in set dom entries & entries ( i ) . GetDN () = dn = > RESULT = i ) ;
Pedro Pereira, Ulisses Costa LDAP em VDM++

22. Transitive Closure
public T r ans iti veCl osu re : nat1 == > set of nat1
T r a n s i t i v eCl osu re ( origem ) ==
(
dcl res : set of nat1 := {};
dcl childs : set of nat1 := dit ( origem ) ;
while childs <> {} do
(
for all c in set childs do
(
childs := childs union dit ( c ) ;
res := res union { c };
);
childs := childs res ;
);
return res ;
)
pre origem in set dom entries
post forall e in set RESULT & ( elems entries ( origem ) . GetDN () ) subset ( elems
entries ( e ) . GetDN () ) ;
Pedro Pereira, Ulisses Costa LDAP em VDM++