212 lines
7.4 KiB
HTML
212 lines
7.4 KiB
HTML
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>LDAP API Overview</title>
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<h2>LDAP API Overview</h2>
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<p>Lightweight Directory Access Protocol (LDAP) is an Internet protocol to
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access directory servers. The directories on the Internet may be "pure" LDAP
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directories; that is, they only communicate through LDAP, or they may be X.500
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or other types of servers that allow access through LDAP. Access to servers
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that are not pure LDAP servers is accomplished through an LDAP gateway.
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Gateways from LDAP to other protocols also are common. Client programs that
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allow a user to access an LDAP directory are called LDAP clients. Applications
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that extract information from an LDAP directory are referred to as <strong>
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LDAP-enabled</strong>.</p>
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<p> The LDAP client is part of the i5/OS<SUP>(TM)</SUP>. The LDAP client is used by i5/OS
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and customer applications for access to LDAP-enabled directories in the
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network. The directories being accessed may or may not be located on an i5/OS
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server. The applications access the LDAP client by using these client APIs.
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TCP/IP is always used to access remote directories, and the administrator can
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configure the connection to use the Secure Sockets Layer (SSL). Also, the
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administrator can select to use Kerberos.</p>
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<p>The LDAP APIs are designed to provide a suite of functions that can be used
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to develop directory enabled applications. Directory-enabled applications
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typically connect to one or more directories and perform various
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directory-related operations, such as:</p>
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<ul>
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<li>Adding entries</li>
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<li>Searching the directory and obtaining the resulting list of entries</li>
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<li>Deleting entries</li>
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<li>Modifying entries</li>
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<li>Renaming entries</li>
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</ul>
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The type of information that is managed in the directory depends on the nature
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of the application. Directories are often used to provide public access to
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information about people, including:
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<ul>
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<li>Phone numbers</li>
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<li>E-mail addresses</li>
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<li>Fax numbers</li>
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<li>Mailing addresses</li>
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</ul>
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<p>Increasingly, directories are being used to manage and publish other types
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of information, including:</p>
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<ul>
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<li>Configuration information</li>
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<li>Public key certificates (managed by certification authorities)</li>
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<li>Access control information</li>
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<li>Locating information (how to find a service)</li>
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</ul>
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<p>The LDAP APIs provide for both synchronous and asynchronous access to a
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directory. Asynchronous access makes it easy for your application to do other
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work while waiting for the results of a potentially lengthy directory operation
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to be returned by the server.</p>
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<br>
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<h3>Typical API Usage</h3>
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<p>The basic interaction is as follows. A connection is made to an LDAP server
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by calling <strong>ldap_init</strong> (or <strong>ldap_ssl_init</strong>, which
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is used to establish a secure connection over Secure Sockets Layer (SSL)).</p>
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<p>An LDAP bind operation is performed by calling <strong>
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ldap_simple_bind</strong> or <strong>ldap_sasl_bind</strong>. The bind
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operation is used to authenticate to the directory server. Note that the LDAP
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V3 API and protocol permits the bind to be skipped, in which case the access
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rights associated with anonymous access are obtained.</p>
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<p>Next, other operations are performed by calling one of the synchronous or
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asynchronous routines (that is, <strong>ldap_search_s</strong> or <strong>
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ldap_search</strong> followed by <strong>ldap_result</strong>).</p>
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<p>Results returned from these routines are interpreted by calling the LDAP
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parsing routines, which include operations such as:</p>
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<ul>
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<li>ldap_first_entry, ldap_next_entry</li>
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<li>ldap_get_dn</li>
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<li>ldap_first_attribute, ldap_next_attribute</li>
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<li>ldap_get_values</li>
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<li>ldap_parse_result (new for LDAP V3)</li>
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<li>etc.</li>
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</ul>
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<p>The LDAP connection is terminated by calling ldap_unbind.</p>
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<p>The ldap_set_rebind_proc routine can be used to define the entry-point of a
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routine to be called when an LDAP bind operation needs to occur when handling a
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client referral to another server.</p>
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<br>
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<h3>Displaying Results</h3>
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<p>Results obtained from the ldap search routines can be accessed by calling
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<strong>ldap_first_entry</strong> and <strong>ldap_next_entry</strong> to step
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through the entries returned, <strong>ldap_first_attribute</strong> and
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<strong>ldap_next_attribute</strong> to step through an entry's attributes,
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<strong>ldap_get_values</strong> to retrieve a given attribute's value, and
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then calling printf or some other display or usage method to display the
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values.</p>
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<br>
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<h3>Uniform Resource Locators (URLS)</h3>
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<p>The <strong>ldap_is_ldap_url</strong> routines can be used to test a URL to
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see if it is an LDAP URL, to parse LDAP URLs into their component pieces, and
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to initiate searches directly using an LDAP URL.</p>
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<p>Examples of these routines are ldap_url_parse, ldap_url_search_s, and
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ldap_is_ldap_url.</p>
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<br>
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<h3>Secure Socket Layer (SSL) Support</h3>
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<p>The LDAP APIs have been extended to support connections that are protected
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by the Secure Socket Layer (SSL) protocol. This can be used to provide strong
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authentication between the client and server, as well as data encryption of
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LDAP messages that flow between the client and the LDAP server. The
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ldap_ssl_client_init() and ldap_ssl_init() APIs are provided to initialize the
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SSL function, and to create a secure SSL connection (respectively).</p>
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<p>When using <a href="ldap_ssl_client_init.htm">ldap_ssl_client_init()</a>,
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the application ID used is QIBM_GLD_DIRSRV_CLIENT, identified as client
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application "Directory Services Client" in Digital Certificate Manager (DCM).
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To use i5/OS application IDs other than the default which have an association
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to a certificate store and a particular certificate in that store, the
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following i5/OS-specific APIs are provided:</p>
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<p> Version 2 API</p>
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<ul>
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<li>ldap_app_ssl_start_np() (deprecated)</li>
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</ul>
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<p> Version 3 API</p>
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<ul>
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<li>ldap_app_ssl_client_init_np()</li>
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</ul>
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<p>When using ldap_ssl_init(), the server is not contacted until the connection
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is used; that is, by ldap_bind() or ldap_search(). If an SSL error occurs while
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trying to connect, the SSL error code can be retrieved for the connection with
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the <a href="ldap_get_option.htm">ldap_get_option()</a> API using the <strong>
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LDAP_OPT_EXT_ERROR</strong> option.</p>
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<br>
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center">
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<a href="#Top_Of_Page">Top</a> |
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<a href="dirserv1.htm">Directory Server APIs</a> |
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<a href="aplist.htm">APIs by
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category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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