snmp.php shadows six core lib/snmp.php functions with incompatible signatures

[somethingwithproof]

snmp.php defines six functions and four constants under the same names Cacti core uses in lib/snmp.php:

Function	hmib	core
cacti_snmp_get	snmp.php:43	lib/snmp.php:127
cacti_snmp_getnext	snmp.php:163	lib/snmp.php:308
cacti_snmp_walk	snmp.php:271	lib/snmp.php:745
format_snmp_string	snmp.php:425	lib/snmp.php:934
snmp_escape_string	snmp.php:568	lib/snmp.php:1122
snmp_get_method	snmp.php:576	lib/snmp.php:1150

Plus REGEXP_SNMP_TRIM, SNMP_METHOD_PHP, SNMP_METHOD_BINARY and SNMP_ESCAPE_CHARACTER, all bare define() with no defined() check.

This does not fire today. Core loads lib/snmp.php only from inside update_reindex_cache() and query_snmp_host(), never at file scope, and the two entry points stay apart: poller_hmib.php includes plugins/hmib/snmp.php, poller_graphs.php includes lib/snmp.php, and poller_hmib.php:524 launches the latter through exec_background(), so they are separate processes. Each process consistently sees one implementation.

It is filed as a hazard rather than a bug. Any change to that include graph turns it into a fatal, and the failure modes differ:

function: PHP Fatal error: Cannot redeclare snmp_get_method()
constant: PHP Warning: Constant SNMP_METHOD_PHP already defined   (keeps the first value)

The constant case is worse than it looks. It does not stop execution, so whichever file loaded first silently wins, and SNMP_ESCAPE_CHARACTER decides how community strings are quoted for the shell.

A function_exists() guard would be the wrong fix. The signatures are not compatible:

// core
cacti_snmp_get(..., $port = 161, $timeout_ms = 500, $retries = 0,
               $environ = 'SNMP', $engineid = '', $value_output_format, ?$native_get)
// hmib
cacti_snmp_get(..., $port = 161, $timeout = 500, $retries = 0,
               $max_oids = 10, $method = SNMP_VALUE_LIBRARY, $environ = SNMP_POLLER)

Core's fourteenth parameter is $environ; hmib's is $max_oids. Guarding would bind hmib's callers to core's function with positional arguments that mean something else, which is quieter and worse than the redeclare. Deleting the copies has the same problem.

Suggested fix. Rename the six to an hmib_ prefix and give the four constants defined() guards. The change is contained: all seven external call sites are in poller_hmib.php (cacti_snmp_walk x4, cacti_snmp_get x3), and the other three functions are only called from within snmp.php itself. cacti_snmp_getnext has no callers at all and could go.

That is behaviour-preserving. Adopting core's implementations instead would be the better end state, but it is a real behaviour change and wants its own testing against live devices.

Found while surveying duplicated helpers across the Cacti plugins; hmib is the only one shadowing core function names.