Collaborative Cuisine's 1 Hour JNDI Cookbook

Lotus Software - Messaging & Collaboration
Confidential | June 2, 2003 | LSM Seminar 2003 © 2002 IBM Corporation
From Now To Next
Ken Lin
Senior Software Engineer
klin@us.ibm.com
Collaborative Cuisine's
1 Hour JNDI Cookbook

Lotus Software - Messaging and Collaboration
© 2002 IBM CorporationCollaborative Cuisine's 1 Hour JNDI Cookbook | LSM Seminar 2003
Goals
Review common directory-related
collaboration scenarios
Examine solutions through algorithms
and JNDI code
Refine and improve solutions

From Now To Next
Starters
Main Courses
Desserts
Tidy Up
Today's Menu

From Now To Next
Locate a Directory Server
Resolve and Authenticate a User
Starters

Locate a Directory Server
Properties File
Configured by each application administrator
Application-dependent solution
Easy to code via java.util.Properties
Manageable when few applications
RFC 2782 - A DNS RR for specifying the location of services
(DNS SRV)
Configured centrally by DNS administrator
Application-independent solution
Easy to code via JNDI
Manageable even when many applications
Recognized by com.sun.jndi.ldap.LdapCtxFactory in
JDK 1.4.1

DNS SRV (RFC 2782)
w32 [C:] winntsystem32nslookup
Default Server: ns1.iris.com
Address: 9.95.aaa.bbb
> set q=srv
> _ldap._tcp.iris.com you type this
0=highest
65535=lowest
Server: ns1.iris.com
Address: 9.95.aaa.bbb
_ldap._tcp.iris.com SRV service location:
priority = 0
weight = 0
port = 389
svr hostname = clapton.iris.com
_ldap._tcp.iris.com SRV service location:
priority = 100
weight = 0
port = 389
svr hostname = little-village.iris.com
clapton.iris.com internet address = 9.95.ccc.ddd
little-village.iris.com internet address = 9.95.eee.fff
>^Z

DirServer.getServers returns host:port strings
public static Vector getServers(String domain) throws NamingException {
Vector servers = new Vector();
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.dns.DnsContextFactory");
DirContext ctx = new InitialDirContext(env);
Attributes attrs = ctx.getAttributes("_ldap._tcp." + domain, new String[] {"SRV"});
Attribute srv = attrs.get("SRV");
if (srv != null) {
NamingEnumeration results = srv.getAll();
if (results.hasMore()) {
while (results.hasMore()) {
String result = (String)results.next();
StringTokenizer tokens = new StringTokenizer(result, " ");
String priority = tokens.nextToken();
String weight = tokens.nextToken();
String port = tokens.nextToken();
String target = tokens.nextToken();
servers.add(target + ":" + port);
}
}
}
return servers;
}
J2SE 1.4.1 or higher

Resolve and Authenticate Users
How do we code
applications to
authenticate using
"friendly" names?
cn=ken lin,ou=westford,o=ibm
is not very friendly!

Resolve and Authenticate Users Algorithm
Does the supplied name look like an LDAP DN?
Yes: ask the LDAP server if DN exists?
Yes: go to Authenticated Bind
No: go to Resolve DN
No: go to Resolve LDAP DN
Resolve supplied name to LDAP DN
Unauthenticated search the name to obtain its DN
(&(objectclass=person)(|(uid={0})(mail={0})(cn={0})))
Allow the filter to be customized to fit customer
(&(objectclass=person)(telephonenumber={0}))
If number of search hits is ...
0: name not found
1: go to Authenticated Bind
otherwise: ambiguous DN
Authenticated Bind
Use LDAP DN and supplied password

DirUser.authenticate to Authenticate and Resolve a Name
boolean authenticate(String hostport, String anyname, String password) throws
NamingException
{
boolean authenticated = false;
DirContext ctx = null;
try {
String dn = resolve(anyname);
if (dn != null) {
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, m_ServiceProvider);
env.put(Context.PROVIDER_URL, "ldap://" + hostport);
env.put(Context.SECURITY_AUTHENTICATION, "simple");
env.put(Context.SECURITY_PRINCIPAL, dn);
env.put(Context.SECURITY_CREDENTIALS, password);
ctx = new InitialDirContext(env);
authenticated = true;
}
} catch (AuthenticationException e) {
authenticated = false;
} finally {
try {
if (ctx != null) ctx.close();
} catch (Exception e) {
}
}
return authenticated;
}
"com.sun.jndi.ldap.LdapCtxFactory"
local DirContext for dn/password

DirUser.resolve to Get a DN from anyname
String resolve(String anyname) throws NamingException
{
// If anyname looks like it might be a DN, try a base search
if (anyname.indexOf("=") != -1) {
try {
Attributes attrs = m_Ctx.getAttributes(anyname);
return anyname;
} catch (NameNotFoundException e) {
// not a valid or known DN, try filtered search
}
}
// anyname must not look like a DN, search for m_FilterPattern with anyname
Object args[] = {anyname};
String filter = java.text.MessageFormat.format(m_FilterPattern, args);
SearchControls ctls = new SearchControls();
ctls.setReturningAttributes(null);
ctls.setCountLimit(1);
ctls.setSearchScope(SearchControls.SUBTREE_SCOPE);
NamingEnumeration results = m_Ctx.search(m_Base, filter, ctls);
if (results.hasMore()) {
SearchResult result = (SearchResult)results.next();
return result.getName();
} else {
throw new NameNotFoundException("Neither DN nor filter hits");
}
}
"(&(objectclass=person)
(|(uid={0})(mail={0})(cn={0})))"
DirContext for this application
some vendors require base
so more than 1 result causes
SizeLimitExceededException

From Now To Next
Find a Member's Group
Find a Group's Members
Main Courses

Directory Groups
IETF, Defacto, and Vendor Group Definitions
Definitions for Static Groups in IETF RFC 2782
groupOfNames / member
groupOfUniqueNames / uniqueMember
Group operations are coded by the application, not the
LDAP server!
Applications must understand schema
Applications must code findMembers
Applications must code findGroups

dgservlet Demo

Two Common Uses for findMembers and findGroups
findMembers can be used
to expand and flatten out a
buddy list
findGroups can be used to
create Notes-like NamesLists
for authorization

DirGroups Class
public class DirGroups
{
protected DirContext m_Ctx = null;
protected NameParser m_Parser = null;
protected String m_GroupObjectClasses[] = {"groupOfNames"};
protected String m_MemberNames[] = {"member"};
protected String m_Base = "";
protected String m_MemberFilter = "(&(objectclass=groupOfNames)(member={0}))";
protected int m_FindMembersDepth = 10;
protected String m_MemberAttrIds[] = {"objectclass", "member", "cn"};
public DirGroups(DirContext ctx) {
m_Ctx = ctx;
}
public void findGroups(String memberDN, Hashtable groups) throws NamingException
{ described later... }
public void findMembers(Name groupDN, Hashtable groups,
Hashtable users, Hashtable unknown) throws NamingException
{ described later... }
etc...
}

findMembers Algorithm
get entry g from groupDN and verify it is a group
foreach memberDN in g {
if memberDN isn't in groups, users, or unknown {
get entry m from memberDN
if m is a group --> add m to groups and recurse...
findMembers(memberDN, groups, users, unknown)
if m is a non-group --> add m to users
if m's objectclass is unknown --> add m to unknown
}
}
findMembers(in String groupDN,
inout Hashtable groups,
inout Hashtable users,
inout Hashtable unknown)
Optimize!

DirGroups.findMembers
public void findMembers(Name groupDN,
Hashtable groups,
Hashtable users,
Hashtable unknown)
throws NamingException
{
// Verify arguments
if (groupDN == null ||
groups == null || users == null || unknown == null)
{
return;
}
// Verify the groupDN is really a group
Attributes attrs = m_Ctx.getAttributes(groupDN, m_MemberAttrIds);
if (!isGroup(attrs)) {
throw new NamingException("'objectclass' is not a group");
}
findMembers(attrs, m_FindMembersDepth, groups, users, unknown);
}
DirContext for this DirGroups object
10
{"objectclass", "member", "cn"}

DirGroups.findMembers
private void findMembers(Attributes attrs, int depth, Hashtable groups,
Hashtable users,Hashtable unknown) throws NamingException {
if (depth <= 0) { return; }
for (int i = 0; i < m_MemberNames.length; i++) {
Attribute attr = attrs.get(m_MemberNames[i]);
if (attr != null) {
NamingEnumeration members = attr.getAll();
while (members.hasMore()) {
Name memberDN = toName((String)members.nextElement());
// Process memberDN only if it hasn't yet been encounterred
if (!users.containsKey(memberDN) && !groups.containsKey(memberDN) &&
!unknown.containsKey(memberDN)) {
try {
if (isGroup(memberDN)) { // memberDN is a group
attrs = m_Ctx.getAttributes(memberDN, m_MemberAttrIds);
if (groups.put(memberDN, attrs) == null) {
findMembers(attrs, depth-1, groups, users, unknown);
}
} else { // memberDN is a non-group
users.put(memberDN, memberDN/*null*/);
}
} catch (NamingException e) { // memberDN is unknown
unknown.put(memberDN, memberDN/*null*/);
}
}
} // while
}
} // for
}
{"objectclass",
"member", "cn"}
{"member"}

DirGroups.isGroup
private boolean isGroup(Name name)
{
if (m_GroupObjectClasses.length == 1) {
return compare(name, "objectclass", m_GroupObjectClasses[0]);
} else {
Attributes attrs = m_Ctx.getAttributes(name, m_MemberAttrIds);
return isGroup(attrs);
}
}
private boolean isGroup(Attributes attrs)
{
Attribute attr = attrs.get("objectclass");
if (attr != null) {
for (int i = 0; i < m_GroupObjectClasses.length; i++) {
if (attr.contains(m_GroupObjectClasses[i])) {
return true;
}
}
return false;
} else {
throw new NamingException("'objectclass' attribute not found");
}
}
LDAP compare is faster than search
{"groupOfNames"}

DirGroups.compare
private boolean compare(Name name, String attr, String value)
{
ctls.setSearchScope(SearchControls.OBJECT_SCOPE);
ctls.setReturningAttributes(new String[0]); // no attributes
// LDAP compare operation
NamingEnumeration results = m_Ctx.search(name, "(" + attr + "=" + value + ")",
ctls);
return results.hasMore(); // if successful, results will contain a single item
}

findGroups Algorithm
findGroups(in String memberDN,
inout Hashtable groups)
g = DNs of groups that memberDN
is a direct member
tovisit = g
while tovisit is not empty {
pop any groupDN from tovisit
if groupDN is not in groups {
groups += groupDN
g = DNs of groups that groupDN
is a direct member of
tovisit += elements of g not in
tovisit or groups
}
}
1. cn=bugs bunny,o=toons
empty
2. cn=looney toons
3. cn=looney toons
4. cn=looney toons
empty
5. cn=looney toons
6. cn=all toons
7. cn=all toons
8. cn=all toons
9. cn=all toons
empty
10. cn=looney toons
cn=all toons
11. empty
12. empty

DirGroups.findGroups
public void findGroups(Name memberDN,
Hashtable groups)
{
Hashtable tovisit = new Hashtable(); // DNs of groups to visit
// Initialize tovisit to groups that memberDN is a direct member of.
putDirectGroups(memberDN, tovisit, groups);
// groups = union(groups, tovisit)
while (!tovisit.isEmpty()) {
// Pop groupDN from tovisit
Name groupDN = (Name)tovisit.keys().nextElement();
tovisit.remove(groupDN);
// Add groupDN to groups
if (groups.put(groupDN, groupDN) == null) {
// Wasn't previously processed, search what groups it is a
// member of.
try {
putDirectGroups(groupDN, tovisit, groups);
} catch (NamingException e) {
e.printStackTrace();
}
} else {
// Was processed previously, don't do anything
}
}
}

DirGroups.putDirectGroups
private void putDirectGroups(Name memberDN,
Hashtable tovisit,
Hashtable groups)
{
// Find in results the groups that memberDN is a direct member of.
NamingEnumeration results = findDirectGroups(memberDN);
// Put each group in tovisit if it doesn't already exist in tovisit or
// groups.
while (results.hasMore()) {
SearchResult result = (SearchResult)results.next();
Name groupDN = toName(result.getName());
if (!groups.containsKey(groupDN) && !tovisit.contains(groupDN)) {
tovisit.put(groupDN, groupDN);
}
}
}

DirGroups.findDirectGroups
private NamingEnumeration findDirectGroups(Name memberDN)
{
Object args[] = {memberDN};
String filter = java.text.MessageFormat.format(m_MemberFilter, args);
String[] attrIDs = {};
ctls.setReturningAttributes(attrIDs);
ctls.setSearchScope(SearchControls.SUBTREE_SCOPE);
NamingEnumeration results = m_Ctx.search(m_Base, filter, ctls);
return results;
}
"(&(objectclass=groupOfNames)
(member={0}))"
some vendors require base
DirContext for this DirGroups object

From Now To Next
Domino LDAP Server Tips
Client-side LDAP Improvements
Two and Three-Tier Architectures
Desserts

DirUser.m_FilterPattern =
"(&(objectclass=person)(|(uid={0})(mail={0})(cn={0})))"
More "|" terms increases search time
FT Index Domino Directory if term cannot be serviced by view
search
DirGroups.m_GroupObjectClasses = {"groupOfNames"}
Uses slightly more efficient LDAP compare instead LDAP
search
Use {"groupOfUniqueNames"} when running against Netscape
only
Use {"groupOfNames", "groupOfUniqueNames"} when running
against LDAP servers from various vendors
Domino 6 LDAP Query-Results Cache
Domino 6.02 LDAP improves DirGroups.findMembers response
for attributes with hundreds of values
Use LDAPDEBUG=1 in Notes.ini to trace LDAP server
Domino LDAP Server Tips

Client-side LDAP Improvements
Eliminate trips to LDAP server for duplicated group queries
findMembers("cn=Iris Directory Team", ...)
findGroups("cn=ken lin,ou=westford,o=ibm", ...)
Reduce trips to LDAP server for "similar" group queries
findMembers("cn=Iris Directory Team", ...) vs.
findMembers("cn=LDAP Server Dev', ...)
findGroups("cn=ken lin,ou=westford,o=ibm") -> 104 groups vs.
findGroups("cn=scott m davidson,ou=westford,o=ibm") -> 135
groups
Eliminate trips to LDAP server for duplicated name resolution
queries
TBD - improve DirGroups.isGroup by consulting cached
"objectclass=groupOfNames" results (FT Index)
TBD - cache LDAP bind requests

InitialDirContextCache
Extends javax.naming.InitialDirContext
Overrides and caches DirContext's getAttributes and search
DirGroups
or other
JNDI calls
Initial-
DirContext-
Cache
Initial
DirContext
LDAP
ServerApp
Internally, query-results caches are implemented via Hashtables
Name.compareTo() is important for Hashtable entry comparison
Not a single line of DirGroups or your JNDI calls was changed to
take advantage of caching!

InitialDirContextCache.getAttributes
public Attributes getAttributes(Name name, String[] attrIds) throws NamingException
{
String key = toKey(name, attrIds);
Object cached = m_AttributesCache.get(key);
Attributes attrs = null;
if (cached == null) {
try {
attrs = super.getAttributes(name, attrIds);
if (attrs != null) {
Attributes value = (Attributes)attrs.clone();
m_AttributesCache.put(key, value);
}
} catch (NamingException e) {
m_AttributesCache.put(key, e.toString());
throw e;
}
} else {
if (cached instanceof String) {
throw new NamingException(cached.toString());
} else {
attrs = (Attributes)cached;
}
}
return attrs;
}
cache implemented via Hashtable
performs the real LDAP call
makes a 2-tuple from name/attrIDs

Two and Three-Tier Architectures
Two-Tier Architecture
LDAP
Server
JNDI or
DirGroups
App
JNDI or
DirGroups
App
JNDI or
DirGroups
App
JNDI or
DirGroups
App
Back
App
Front
App
Front
App
Front
LDAP
Server
Three-Tier Architecture
e.g., Domino DA, Sametime, J2EE, dgservlet
e.g., Mail clients

From Now To Next
Review
Tomorrow
Questions
Tidy Up

Review
Algorithms and Code
Locate a Directory Server DirServer.getServers()
Resolve and Authenticate a userDirUser.authenticate()
Find a Group's Members DirGroups.findMembers()
Find a Member's Groups DirGroups.findGroups()
Cache Query Results InitialDirContextCache
Improvements

Tomorrow
Run nslookup, look for SRVs
Download seminar samples
Run DirServer.main()
Run DirUser.main()
Install and run dgservlet
Try "real" directories
Experiment!

References
Collaborative Cuisine's 1 Hour JNDI Cookbook - LSM 2003
https://www-914.ibm.com/events/lsm/03lsm.nsf
Building Directory Friendly Applications - LSM 2002
https://www-914.ibm.com/events/lsm/02lsm.nsf/lookupwebpage/AbsPresAppDev
JNDI Tutorial - Tips for LDAP Users
http://java.sun.com/products/jndi/tutorial/ldap/index.html
Java Servlet Technology
http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/Servlets.html
Eclipse - an open extensible IDE
http://eclipse.org
Directory Services Markup Language
http://www.oasis-open.org/cover/dsml.html
The String Representation of LDAP Search Filters
http://www.ietf.org/rfc/rfc2254.txt
A DNS RR for specifying the location of services (DNS SRV)
http://www.ietf.org/internet-drafts/draft-ietf-ldapext-locate-08.txt
A Summary of the X.500(96) User Schema for use with LDAPv3
Misc.
LDAP
JNDI

From Now To Next
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Collaborative Cuisine's 1 Hour JNDI Cookbook

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