PHP ldap_errno() Function: Usage and Examples

Retrieves the numeric error number for the last LDAP operation on a connection. This guide demonstrates its use in PHP code and explains when the result or side effect needs extra checks.

What It Does

Retrieves the numeric error number for the last LDAP operation on a connection.

Syntax and Parameters

The examples below show a real call to ldap_errno with suitable arguments. Read the function call in context: its connection, handle, input data or other prerequisites are created before use.

Requirements: LDAP extension; an LDAPS directory and scoped credentials.

These examples are for an isolated development environment. Hostnames, credentials and remote paths must be replaced with your approved configuration.

Example 1: Core Behavior

Bind to a controlled directory and use a restricted service identity.

<?php
$user = getenv('LDAP_BIND_DN'); $pass = getenv('LDAP_PASSWORD');
if (!$user || !$pass) throw new RuntimeException('LDAP credentials are required');
$ldap = ldap_connect('ldaps://directory.internal.test:636');
if (!$ldap) throw new RuntimeException('LDAP handle unavailable');
ldap_set_option($ldap, LDAP_OPT_PROTOCOL_VERSION, 3);
$base = 'ou=People,dc=example,dc=test';
$dn = 'cn=Demo User,ou=People,dc=example,dc=test';
$filterValue = 'Alice (QA)';
$filter = '(cn=' . ldap_escape($filterValue, '', LDAP_ESCAPE_FILTER) . ')';
if (!ldap_bind($ldap, $user, $pass)) throw new RuntimeException("Directory bind failed");
$resultValue = ldap_errno($ldap);
echo is_bool($resultValue) ? ($resultValue ? "true" : "false") : json_encode($resultValue, JSON_PARTIAL_OUTPUT_ON_ERROR);

Observe the returned value or changed resource state. A successful function call can still require additional checks before a higher-level operation is considered successful.

Example 2: Alternative or Failure Case

The second example uses a different directory record or input value.

<?php
$user = getenv('LDAP_BIND_DN'); $pass = getenv('LDAP_PASSWORD');
if (!$user || !$pass) throw new RuntimeException('LDAP credentials are required');
$ldap = ldap_connect('ldaps://directory.internal.test:636');
if (!$ldap) throw new RuntimeException('LDAP handle unavailable');
ldap_set_option($ldap, LDAP_OPT_PROTOCOL_VERSION, 3);
$base = 'ou=People,dc=example,dc=test';
$dn = 'cn=Example Staff,ou=People,dc=example,dc=test';
$filterValue = 'Alice (QA)';
$filter = '(cn=' . ldap_escape($filterValue, '', LDAP_ESCAPE_FILTER) . ')';
if (!ldap_bind($ldap, $user, $pass)) throw new RuntimeException("Directory bind failed");
ldap_set_option($ldap, LDAP_OPT_NETWORK_TIMEOUT, 5);
$resultValue = ldap_errno($ldap);
echo is_bool($resultValue) ? ($resultValue ? "true" : "false") : json_encode($resultValue, JSON_PARTIAL_OUTPUT_ON_ERROR);

Compare the different inputs, environment assumptions or result checks. Do not use a transport-level success value as proof that all business-level requirements were met.

Practical Example: Applying the Rule

Check permissions, server controls and returned result types before modifying live directory data.

<?php
$user = getenv('LDAP_BIND_DN'); $pass = getenv('LDAP_PASSWORD');
if (!$user || !$pass) throw new RuntimeException('LDAP credentials are required');
$ldap = ldap_connect('ldaps://directory.internal.test:636');
if (!$ldap) throw new RuntimeException('LDAP handle unavailable');
ldap_set_option($ldap, LDAP_OPT_PROTOCOL_VERSION, 3);
$base = 'ou=People,dc=example,dc=test';
$dn = 'cn=Test Member,ou=People,dc=example,dc=test';
$filterValue = 'Alice (QA)';
$filter = '(cn=' . ldap_escape($filterValue, '', LDAP_ESCAPE_FILTER) . ')';
if (!ldap_bind($ldap, $user, $pass)) throw new RuntimeException("Directory bind failed");
ldap_set_option($ldap, LDAP_OPT_NETWORK_TIMEOUT, 6);
$resultValue = ldap_errno($ldap);
echo is_bool($resultValue) ? ($resultValue ? "true" : "false") : json_encode($resultValue, JSON_PARTIAL_OUTPUT_ON_ERROR);

In an application, convert low-level failures into controlled responses and log only non-sensitive diagnostic context.

Important Behavior and Edge Cases

Capture diagnostic information after the failing operation; do not expose raw server details to users.

LDAP filter values and DN values require different escaping flags. Never concatenate unchecked user input into a directory query.

Comparison with Related Functions or Patterns

Common Beginner Mistakes

Key Takeaways

• Retrieves the numeric error number for the last LDAP operation on a connection.
• Capture diagnostic information after the failing operation; do not expose raw server details to users.
• ldap_error reports a string describing the LDAP error.

Select this API or pattern based on its documented behavior and the trust boundaries in your own application, and test all external integrations against their actual deployments.