Add snmp_init_mib function to allow MIB tree to be reset using environment variables (#21452)

Author: eskyuu

ext/snmp/snmp.c

@@ -89,6 +89,8 @@ typedef struct snmp_session php_snmp_session;
 	} \
 }
 
+static int mib_needs_reset;
+
 ZEND_DECLARE_MODULE_GLOBALS(snmp)
 static PHP_GINIT_FUNCTION(snmp);
 
@@ -1629,6 +1631,7 @@ PHP_FUNCTION(snmp_read_mib)
 		RETURN_THROWS();
 	}
 
+	mib_needs_reset = 1;
 	if (!read_mib(filename)) {
 		char *error = strerror(errno);
 		php_error_docref(NULL, E_WARNING, "Error while reading MIB file '%s': %s", filename, error);
@@ -1638,6 +1641,27 @@ PHP_FUNCTION(snmp_read_mib)
 }
 /* }}} */
 
+/* {{{ Resets the MIB tree and set the mib directories to the provided mibdirs. */
+PHP_FUNCTION(snmp_init_mib)
+{
+	zend_string *mibdirs = NULL;
+
+	ZEND_PARSE_PARAMETERS_START(0, 1)
+		Z_PARAM_OPTIONAL
+		Z_PARAM_STR_OR_NULL(mibdirs)
+	ZEND_PARSE_PARAMETERS_END();
+
+	// If the mibdirs has been changed, we need to reset the MIB tree at the end of the request
+	if (mibdirs != NULL) {
+		mib_needs_reset = 1;
+	}
+
+	shutdown_mib();
+	netsnmp_ds_set_string(NETSNMP_DS_LIBRARY_ID, NETSNMP_DS_LIB_MIBDIRS, ZSTR_VAL(mibdirs));
+	init_mib();
+}
+/* }}} */
+
 /* {{{ Creates a new SNMP session to specified host. */
 PHP_METHOD(SNMP, __construct)
 {
@@ -2172,6 +2196,19 @@ PHP_MSHUTDOWN_FUNCTION(snmp)
 }
 /* }}} */
 
+/* {{{ PHP_RSHUTDOWN_FUNCTION */
+static PHP_RSHUTDOWN_FUNCTION(snmp)
+{
+	if (mib_needs_reset) {
+		shutdown_mib();
+		netsnmp_ds_set_string(NETSNMP_DS_LIBRARY_ID, NETSNMP_DS_LIB_MIBDIRS, NULL);
+		init_mib();
+	}
+
+	return SUCCESS;
+}
+/* }}} */
+
 /* {{{ PHP_MINFO_FUNCTION */
 PHP_MINFO_FUNCTION(snmp)
 {
@@ -2199,7 +2236,7 @@ zend_module_entry snmp_module_entry = {
 	PHP_MINIT(snmp),
 	PHP_MSHUTDOWN(snmp),
 	NULL,
-	NULL,
+	PHP_RSHUTDOWN(snmp),
 	PHP_MINFO(snmp),
 	PHP_SNMP_VERSION,
 	PHP_MODULE_GLOBALS(snmp),

ext/snmp/snmp.stub.php

@@ -181,6 +181,8 @@ function snmp_get_valueretrieval(): int {}
 
 function snmp_read_mib(string $filename): bool {}
 
+function snmp_init_mib(?string $mibdirs): void {}
+
 class SNMP
 {
     /** @cvalue SNMP_VERSION_1 */