allow mpm to be note connections that are not TCP based.

CHANGES

@@ -1,6 +1,10 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.1
 
+  *) mpm_event, mpm_worker, mpm_winnt, mpm_prefork: Added optional functions
+     to account for connections managed outside the MPM accept loop (e.g., UDP).
+     [Tarek Ibrahim <tareki@pulsarxtech.com> <t1br4h1m@gmail.com>]
+
   * mod_ssl: Add support for OpenSSL provider based certificate
     stores. [Graham Leggett]
 

docs/log-message-tags/next-number

@@ -1 +1 @@
-10622
+10623

include/ap_mmn.h

@@ -737,14 +737,18 @@
  * 20211221.29 (2.5.1-dev) Add ap_set_time_process_request() to scoreboard.h
  * 20211221.30 (2.5.1-dev) Add ap_stat_check() to httpd.h
  * 20211221.31 (2.5.1-dev) Add ap_*_timingsafe() to httpd.h
+ * 20211221.32 (2.5.1-dev) Add the optional functions ap_mpm_note_extra_
+ *                         connection_added() and ap_mpm_note_extra_
+ *                         connection_removed(), and ap_mpm_wait_for_extra_
+ *                         connections(), to mpm_common.h
  */
 
 #define MODULE_MAGIC_COOKIE 0x41503235UL /* "AP25" */
 
 #ifndef MODULE_MAGIC_NUMBER_MAJOR
 #define MODULE_MAGIC_NUMBER_MAJOR 20211221
 #endif
-#define MODULE_MAGIC_NUMBER_MINOR 31             /* 0...n */
+#define MODULE_MAGIC_NUMBER_MINOR 32            /* 0...n */
 
 /**
  * Determine if the server's current MODULE_MAGIC_NUMBER is at least a

include/mpm_common.h

@@ -40,6 +40,7 @@
 #include "ap_config.h"
 #include "ap_mpm.h"
 #include "scoreboard.h"
+#include "apr_optional.h"
 
 #if APR_HAVE_NETINET_TCP_H
 #include <netinet/tcp.h>    /* for TCP_NODELAY */
@@ -560,6 +561,34 @@ AP_DECLARE_HOOK(void, child_stopped,
  */
 void mpm_common_pre_config(apr_pool_t *pconf);
 
+/**
+ * Report a connection which the MPM did not accept itself, so that a child
+ * stopping gracefully waits for it like for its own connections.  Call
+ * ap_mpm_note_extra_connection_added() when such a connection starts and
+ * ap_mpm_note_extra_connection_removed() when it ends.
+ */
+APR_DECLARE_OPTIONAL_FN(void, ap_mpm_note_extra_connection_added, (void));
+APR_DECLARE_OPTIONAL_FN(void, ap_mpm_note_extra_connection_removed, (void));
+
+/**
+ * Make the above optional functions available to modules. To be called from
+ * the pre-config hook of an MPM which waits for noted connections.
+ *
+ * @note An MPM which does not wait for them never calls this, leaving both
+ * functions unavailable.
+ */
+AP_DECLARE(void) ap_mpm_register_extra_connection_fns(void);
+
+/**
+ * Wait for the connections noted by modules to be gone, for at most
+ * max(Timeout, GracefulShutdownTimeout). To be called by an MPM child
+ * that is about to exit gracefully.
+ *
+ * @note If tracked connections remain when the timeout expires, a warning is
+ * logged and the child exits, potentially terminating those connections.
+ */
+AP_DECLARE(void) ap_mpm_wait_for_extra_connections(void);
+
 #ifdef __cplusplus
 }
 #endif

server/mpm/event/event.c

@@ -973,6 +973,10 @@ static apr_status_t event_request_cleanup(void *dummy)
     event_conn_state_t *cs = ap_get_module_config(c->conn_config,
                                                   &mpm_event_module);
 
+    if (!cs) {
+        return APR_SUCCESS;
+    }
+
     cs->r = NULL;
     return APR_SUCCESS;
 }
@@ -982,6 +986,10 @@ static void event_pre_read_request(request_rec *r, conn_rec *c)
     event_conn_state_t *cs = ap_get_module_config(c->conn_config,
                                                   &mpm_event_module);
 
+    if (!cs) {
+        return;
+    }
+
     cs->r = r;
     cs->sc = ap_get_module_config(ap_server_conf->module_config,
                                   &mpm_event_module);
@@ -999,6 +1007,10 @@ static int event_post_read_request(request_rec *r)
     event_conn_state_t *cs = ap_get_module_config(c->conn_config,
                                                   &mpm_event_module);
 
+    if (!cs) {
+        return DECLINED;
+    }
+
     /* To preserve legacy behaviour (consistent with other MPMs), use
      * the keepalive timeout from the base server (first on this IP:port)
      * when none is explicitly configured on this server.
@@ -3139,6 +3151,10 @@ static void child_main(int child_num_arg, int child_bucket)
                      rv == AP_MPM_PODX_GRACEFUL ? "graceful" : "ungraceful");
     }
 
+    if (terminate_mode == ST_GRACEFUL) {
+        ap_mpm_wait_for_extra_connections();
+    }
+
     free(threads);
 
     clean_child_exit(resource_shortage ? APEXIT_CHILDSICK : 0);
@@ -3876,6 +3892,10 @@ static void setup_slave_conn(conn_rec *c, void *csd)
     event_conn_state_t *cs;
 
     mcs = ap_get_module_config(c->master->conn_config, &mpm_event_module);
+    if (!mcs) {
+        /* Master connection is not managed by this MPM; nothing to inherit. */
+        return;
+    }
 
     cs = apr_pcalloc(c->pool, sizeof(*cs));
     cs->c = c;
@@ -3914,7 +3934,9 @@ static int event_protocol_switch(conn_rec *c, request_rec *r, server_rec *s,
         event_conn_state_t *cs;
 
         cs = ap_get_module_config(c->conn_config, &mpm_event_module);
-        cs->sc = ap_get_module_config(s->module_config, &mpm_event_module);
+        if (cs) {
+            cs->sc = ap_get_module_config(s->module_config, &mpm_event_module);
+        }
     }
     return DECLINED;
 }
@@ -3954,6 +3976,8 @@ static int event_pre_config(apr_pool_t * pconf, apr_pool_t * plog,
     const char *userdata_key = "mpm_event_module";
     int test_atomics = 0;
 
+    ap_mpm_register_extra_connection_fns();
+
     debug = ap_exists_config_define("DEBUG");
 
     if (debug) {

server/mpm/prefork/prefork.c

@@ -229,6 +229,9 @@ static void clean_child_exit_ex(int code, int from_signal)
     if (pchild) {
         if (!code && !from_signal) {
             ap_run_child_stopping(pchild, !retained->mpm->is_ungraceful);
+            if (!retained->mpm->is_ungraceful) {
+                ap_mpm_wait_for_extra_connections();
+            }
             ap_run_child_stopped(pchild, !retained->mpm->is_ungraceful);
         }
         apr_pool_destroy(pchild);
@@ -1325,6 +1328,8 @@ static int prefork_pre_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp
     apr_status_t rv;
     const char *userdata_key = "mpm_prefork_module";
 
+    ap_mpm_register_extra_connection_fns();
+
     debug = ap_exists_config_define("DEBUG");
 
     if (debug) {

server/mpm/winnt/child.c

@@ -1262,6 +1262,10 @@ void child_main(apr_pool_t *pconf, DWORD parent_pid)
     ap_log_error(APLOG_MARK, APLOG_NOTICE, APR_SUCCESS, ap_server_conf, APLOGNO(00364)
                  "Child: All worker threads have exited.");
 
+    if (graceful_shutdown) {
+        ap_mpm_wait_for_extra_connections();
+    }
+
     ap_run_child_stopped(pchild, graceful_shutdown);
 
     apr_thread_mutex_destroy(child_lock);

server/mpm/winnt/mpm_winnt.c

@@ -1368,6 +1368,8 @@ static int winnt_pre_config(apr_pool_t *pconf_, apr_pool_t *plog, apr_pool_t *pt
      *   -k runservice [WinNT errors logged from rewrite_args]
      */
 
+    ap_mpm_register_extra_connection_fns();
+
     /* Initialize shared static objects.
      * TODO: Put config related statics into an sconf structure.
      */

server/mpm/worker/worker.c

@@ -1328,6 +1328,10 @@ static void child_main(int child_num_arg, int child_bucket)
                      rv == AP_MPM_PODX_GRACEFUL ? ST_GRACEFUL : ST_UNGRACEFUL);
     }
 
+    if (terminate_mode == ST_GRACEFUL) {
+        ap_mpm_wait_for_extra_connections();
+    }
+
     free(threads);
 
     clean_child_exit(resource_shortage ? APEXIT_CHILDSICK : 0);
@@ -2103,6 +2107,8 @@ static int worker_pre_config(apr_pool_t *pconf, apr_pool_t *plog,
     apr_status_t rv;
     const char *userdata_key = "mpm_worker_module";
 
+    ap_mpm_register_extra_connection_fns();
+
     debug = ap_exists_config_define("DEBUG");
 
     if (debug) {

server/mpm_common.c

@@ -34,6 +34,7 @@
 #include "apr_getopt.h"
 #include "apr_optional.h"
 #include "apr_allocator.h"
+#include "apr_atomic.h"
 
 #include "httpd.h"
 #include "http_config.h"
@@ -185,6 +186,52 @@ AP_DECLARE_DATA apr_size_t ap_thread_stacksize;
 #define ALLOCATOR_MAX_FREE_DEFAULT (2048*1024)
 AP_DECLARE_DATA apr_uint32_t ap_max_mem_free = ALLOCATOR_MAX_FREE_DEFAULT;
 
+static apr_uint32_t extra_connection_count = 0; /* Number of open connections that the MPM does not own */
+
+static void ap_mpm_note_extra_connection_added(void)
+{
+    apr_atomic_inc32(&extra_connection_count);
+}
+
+static void ap_mpm_note_extra_connection_removed(void)
+{
+    apr_atomic_dec32(&extra_connection_count);
+}
+
+AP_DECLARE(void) ap_mpm_register_extra_connection_fns(void)
+{
+    APR_REGISTER_OPTIONAL_FN(ap_mpm_note_extra_connection_added);
+    APR_REGISTER_OPTIONAL_FN(ap_mpm_note_extra_connection_removed);
+}
+
+AP_DECLARE(void) ap_mpm_wait_for_extra_connections(void)
+{
+    apr_uint32_t count = apr_atomic_read32(&extra_connection_count);
+    apr_time_t graceful, timeout, deadline;
+
+    if (count == 0) {
+        return;
+    }
+
+    graceful = apr_time_from_sec(ap_graceful_shutdown_timeout);
+    timeout = (graceful > ap_server_conf->timeout) ? graceful : ap_server_conf->timeout;
+    deadline = apr_time_now() + timeout;
+
+    do {
+        apr_sleep(apr_time_from_msec(100));
+        count = apr_atomic_read32(&extra_connection_count);
+    } while (count > 0 && apr_time_now() < deadline);
+
+    if (count > 0) {
+        ap_log_error(APLOG_MARK, APLOG_WARNING, 0, ap_server_conf,
+                     APLOGNO(10622)
+                     "Child: %u connection(s) noted by modules did not "
+                     "finish within %" APR_TIME_T_FMT " seconds, "
+                     "exiting anyway",
+                     count, apr_time_sec(timeout));
+    }
+}
+
 /* Set defaults for config directives implemented here.  This is
  * called from core's pre-config hook, so MPMs which need to override
  * one of these should run their pre-config hook after that of core.