Previously, I had added the ast_sched_thread stuff that was a generic scheduler thread implementation. However, if you used it, it required using different functions for modifying scheduler contents. This patch reworks how this is done and just allows you to optionally start a thread on the original scheduler context structure that has always been there. This makes it trivial to switch to the generic scheduler thread implementation without having to touch any of the other code that adds or removes scheduler entries. In passing, I made some naming tweaks to add ast_ prefixes where they were not there before. Review: https://reviewboard.asterisk.org/r/1007/ git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@299091 65c4cc65-6c06-0410-ace0-fbb531ad65f3
442 lines
11 KiB
C
442 lines
11 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2005-2006, Kevin P. Fleming
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*
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* Kevin P. Fleming <kpfleming@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief Background DNS update manager
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*
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* \author Kevin P. Fleming <kpfleming@digium.com>
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*
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* \bug There is a minor race condition. In the event that an IP address
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* of a dnsmgr managed host changes, there is the potential for the consumer
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* of that address to access the in_addr data at the same time that the dnsmgr
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* thread is in the middle of updating it to the new address.
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*/
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#include "asterisk.h"
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ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
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#include "asterisk/_private.h"
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#include <regex.h>
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#include <signal.h>
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#include "asterisk/dnsmgr.h"
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#include "asterisk/linkedlists.h"
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#include "asterisk/utils.h"
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#include "asterisk/config.h"
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#include "asterisk/sched.h"
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#include "asterisk/cli.h"
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#include "asterisk/manager.h"
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#include "asterisk/acl.h"
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static struct ast_sched_context *sched;
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static int refresh_sched = -1;
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static pthread_t refresh_thread = AST_PTHREADT_NULL;
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struct ast_dnsmgr_entry {
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/*! where we will store the resulting IP address and port number */
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struct ast_sockaddr *result;
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/*! SRV record to lookup, if provided. Composed of service, protocol, and domain name: _Service._Proto.Name */
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char *service;
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/*! Set to 1 if the entry changes */
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unsigned int changed:1;
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ast_mutex_t lock;
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AST_RWLIST_ENTRY(ast_dnsmgr_entry) list;
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/*! just 1 here, but we use calloc to allocate the correct size */
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char name[1];
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};
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static AST_RWLIST_HEAD_STATIC(entry_list, ast_dnsmgr_entry);
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AST_MUTEX_DEFINE_STATIC(refresh_lock);
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#define REFRESH_DEFAULT 300
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static int enabled;
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static int refresh_interval;
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struct refresh_info {
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struct entry_list *entries;
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int verbose;
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unsigned int regex_present:1;
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regex_t filter;
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};
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static struct refresh_info master_refresh_info = {
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.entries = &entry_list,
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.verbose = 0,
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};
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struct ast_dnsmgr_entry *ast_dnsmgr_get(const char *name, struct ast_sockaddr *result, const char *service)
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{
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struct ast_dnsmgr_entry *entry;
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int total_size = sizeof(*entry) + strlen(name) + (service ? strlen(service) + 1 : 0);
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if (!result || ast_strlen_zero(name) || !(entry = ast_calloc(1, total_size))) {
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return NULL;
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}
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entry->result = result;
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ast_mutex_init(&entry->lock);
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strcpy(entry->name, name);
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if (service) {
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entry->service = ((char *) entry) + sizeof(*entry) + strlen(name);
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strcpy(entry->service, service);
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}
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AST_RWLIST_WRLOCK(&entry_list);
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AST_RWLIST_INSERT_HEAD(&entry_list, entry, list);
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AST_RWLIST_UNLOCK(&entry_list);
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return entry;
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}
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void ast_dnsmgr_release(struct ast_dnsmgr_entry *entry)
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{
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if (!entry)
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return;
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AST_RWLIST_WRLOCK(&entry_list);
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AST_RWLIST_REMOVE(&entry_list, entry, list);
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AST_RWLIST_UNLOCK(&entry_list);
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ast_verb(4, "removing dns manager for '%s'\n", entry->name);
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ast_mutex_destroy(&entry->lock);
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ast_free(entry);
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}
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int ast_dnsmgr_lookup(const char *name, struct ast_sockaddr *result, struct ast_dnsmgr_entry **dnsmgr, const char *service)
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{
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if (ast_strlen_zero(name) || !result || !dnsmgr) {
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return -1;
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}
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if (*dnsmgr && !strcasecmp((*dnsmgr)->name, name)) {
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return 0;
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}
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ast_verb(4, "doing dnsmgr_lookup for '%s'\n", name);
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/* do a lookup now but add a manager so it will automagically get updated in the background */
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ast_get_ip_or_srv(result, name, service);
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/* if dnsmgr is not enable don't bother adding an entry */
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if (!enabled) {
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return 0;
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}
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ast_verb(3, "adding dns manager for '%s'\n", name);
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*dnsmgr = ast_dnsmgr_get(name, result, service);
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return !*dnsmgr;
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}
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/*
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* Refresh a dnsmgr entry
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*/
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static int dnsmgr_refresh(struct ast_dnsmgr_entry *entry, int verbose)
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{
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struct ast_sockaddr tmp = { .len = 0, };
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int changed = 0;
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ast_mutex_lock(&entry->lock);
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if (verbose) {
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ast_verb(3, "refreshing '%s'\n", entry->name);
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}
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if (!ast_get_ip_or_srv(&tmp, entry->name, entry->service)) {
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if (!ast_sockaddr_port(&tmp)) {
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ast_sockaddr_set_port(&tmp, ast_sockaddr_port(entry->result));
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}
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if (ast_sockaddr_cmp(&tmp, entry->result)) {
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const char *old_addr = ast_strdupa(ast_sockaddr_stringify(entry->result));
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const char *new_addr = ast_strdupa(ast_sockaddr_stringify(&tmp));
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ast_log(LOG_NOTICE, "dnssrv: host '%s' changed from %s to %s\n",
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entry->name, old_addr, new_addr);
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ast_sockaddr_copy(entry->result, &tmp);
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changed = entry->changed = 1;
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}
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}
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ast_mutex_unlock(&entry->lock);
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return changed;
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}
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int ast_dnsmgr_refresh(struct ast_dnsmgr_entry *entry)
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{
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return dnsmgr_refresh(entry, 0);
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}
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/*
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* Check if dnsmgr entry has changed from since last call to this function
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*/
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int ast_dnsmgr_changed(struct ast_dnsmgr_entry *entry)
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{
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int changed;
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ast_mutex_lock(&entry->lock);
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changed = entry->changed;
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entry->changed = 0;
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ast_mutex_unlock(&entry->lock);
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return changed;
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}
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static void *do_refresh(void *data)
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{
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for (;;) {
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pthread_testcancel();
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usleep((ast_sched_wait(sched)*1000));
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pthread_testcancel();
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ast_sched_runq(sched);
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}
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return NULL;
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}
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static int refresh_list(const void *data)
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{
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struct refresh_info *info = (struct refresh_info *)data;
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struct ast_dnsmgr_entry *entry;
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/* if a refresh or reload is already in progress, exit now */
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if (ast_mutex_trylock(&refresh_lock)) {
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if (info->verbose)
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ast_log(LOG_WARNING, "DNS Manager refresh already in progress.\n");
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return -1;
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}
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ast_verb(3, "Refreshing DNS lookups.\n");
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AST_RWLIST_RDLOCK(info->entries);
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AST_RWLIST_TRAVERSE(info->entries, entry, list) {
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if (info->regex_present && regexec(&info->filter, entry->name, 0, NULL, 0))
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continue;
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dnsmgr_refresh(entry, info->verbose);
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}
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AST_RWLIST_UNLOCK(info->entries);
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ast_mutex_unlock(&refresh_lock);
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/* automatically reschedule based on the interval */
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return refresh_interval * 1000;
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}
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void dnsmgr_start_refresh(void)
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{
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if (refresh_sched > -1) {
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AST_SCHED_DEL(sched, refresh_sched);
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refresh_sched = ast_sched_add_variable(sched, 100, refresh_list, &master_refresh_info, 1);
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}
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}
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static int do_reload(int loading);
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static char *handle_cli_reload(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
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{
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switch (cmd) {
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case CLI_INIT:
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e->command = "dnsmgr reload";
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e->usage =
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"Usage: dnsmgr reload\n"
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" Reloads the DNS manager configuration.\n";
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return NULL;
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case CLI_GENERATE:
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return NULL;
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}
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if (a->argc > 2)
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return CLI_SHOWUSAGE;
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do_reload(0);
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return CLI_SUCCESS;
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}
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static char *handle_cli_refresh(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
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{
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struct refresh_info info = {
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.entries = &entry_list,
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.verbose = 1,
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};
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switch (cmd) {
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case CLI_INIT:
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e->command = "dnsmgr refresh";
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e->usage =
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"Usage: dnsmgr refresh [pattern]\n"
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" Peforms an immediate refresh of the managed DNS entries.\n"
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" Optional regular expression pattern is used to filter the entries to refresh.\n";
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return NULL;
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case CLI_GENERATE:
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return NULL;
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}
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if (!enabled) {
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ast_cli(a->fd, "DNS Manager is disabled.\n");
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return 0;
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}
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if (a->argc > 3) {
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return CLI_SHOWUSAGE;
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}
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if (a->argc == 3) {
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if (regcomp(&info.filter, a->argv[2], REG_EXTENDED | REG_NOSUB)) {
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return CLI_SHOWUSAGE;
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} else {
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info.regex_present = 1;
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}
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}
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refresh_list(&info);
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if (info.regex_present) {
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regfree(&info.filter);
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}
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return CLI_SUCCESS;
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}
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static char *handle_cli_status(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
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{
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int count = 0;
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struct ast_dnsmgr_entry *entry;
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switch (cmd) {
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case CLI_INIT:
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e->command = "dnsmgr status";
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e->usage =
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"Usage: dnsmgr status\n"
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" Displays the DNS manager status.\n";
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return NULL;
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case CLI_GENERATE:
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return NULL;
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}
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if (a->argc > 2)
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return CLI_SHOWUSAGE;
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ast_cli(a->fd, "DNS Manager: %s\n", enabled ? "enabled" : "disabled");
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ast_cli(a->fd, "Refresh Interval: %d seconds\n", refresh_interval);
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AST_RWLIST_RDLOCK(&entry_list);
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AST_RWLIST_TRAVERSE(&entry_list, entry, list)
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count++;
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AST_RWLIST_UNLOCK(&entry_list);
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ast_cli(a->fd, "Number of entries: %d\n", count);
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return CLI_SUCCESS;
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}
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static struct ast_cli_entry cli_reload = AST_CLI_DEFINE(handle_cli_reload, "Reloads the DNS manager configuration");
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static struct ast_cli_entry cli_refresh = AST_CLI_DEFINE(handle_cli_refresh, "Performs an immediate refresh");
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static struct ast_cli_entry cli_status = AST_CLI_DEFINE(handle_cli_status, "Display the DNS manager status");
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int dnsmgr_init(void)
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{
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if (!(sched = ast_sched_context_create())) {
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ast_log(LOG_ERROR, "Unable to create schedule context.\n");
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return -1;
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}
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ast_cli_register(&cli_reload);
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ast_cli_register(&cli_status);
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ast_cli_register(&cli_refresh);
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return do_reload(1);
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}
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int dnsmgr_reload(void)
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{
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return do_reload(0);
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}
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static int do_reload(int loading)
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{
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struct ast_config *config;
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struct ast_flags config_flags = { loading ? 0 : CONFIG_FLAG_FILEUNCHANGED };
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const char *interval_value;
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const char *enabled_value;
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int interval;
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int was_enabled;
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int res = -1;
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config = ast_config_load2("dnsmgr.conf", "dnsmgr", config_flags);
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if (config == CONFIG_STATUS_FILEMISSING || config == CONFIG_STATUS_FILEUNCHANGED || config == CONFIG_STATUS_FILEINVALID) {
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return 0;
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}
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/* ensure that no refresh cycles run while the reload is in progress */
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ast_mutex_lock(&refresh_lock);
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/* reset defaults in preparation for reading config file */
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refresh_interval = REFRESH_DEFAULT;
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was_enabled = enabled;
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enabled = 0;
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AST_SCHED_DEL(sched, refresh_sched);
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if (config) {
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if ((enabled_value = ast_variable_retrieve(config, "general", "enable"))) {
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enabled = ast_true(enabled_value);
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}
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if ((interval_value = ast_variable_retrieve(config, "general", "refreshinterval"))) {
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if (sscanf(interval_value, "%30d", &interval) < 1)
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ast_log(LOG_WARNING, "Unable to convert '%s' to a numeric value.\n", interval_value);
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else if (interval < 0)
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ast_log(LOG_WARNING, "Invalid refresh interval '%d' specified, using default\n", interval);
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else
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refresh_interval = interval;
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}
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ast_config_destroy(config);
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}
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if (enabled && refresh_interval)
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ast_log(LOG_NOTICE, "Managed DNS entries will be refreshed every %d seconds.\n", refresh_interval);
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/* if this reload enabled the manager, create the background thread
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if it does not exist */
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if (enabled) {
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if (!was_enabled && (refresh_thread == AST_PTHREADT_NULL)) {
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if (ast_pthread_create_background(&refresh_thread, NULL, do_refresh, NULL) < 0) {
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ast_log(LOG_ERROR, "Unable to start refresh thread.\n");
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}
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}
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/* make a background refresh happen right away */
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refresh_sched = ast_sched_add_variable(sched, 100, refresh_list, &master_refresh_info, 1);
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res = 0;
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}
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/* if this reload disabled the manager and there is a background thread,
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kill it */
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else if (!enabled && was_enabled && (refresh_thread != AST_PTHREADT_NULL)) {
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/* wake up the thread so it will exit */
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pthread_cancel(refresh_thread);
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pthread_kill(refresh_thread, SIGURG);
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pthread_join(refresh_thread, NULL);
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refresh_thread = AST_PTHREADT_NULL;
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res = 0;
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}
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else
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res = 0;
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ast_mutex_unlock(&refresh_lock);
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manager_event(EVENT_FLAG_SYSTEM, "Reload", "Module: DNSmgr\r\nStatus: %s\r/nMessage: DNSmgr reload Requested\r\n", enabled ? "Enabled" : "Disabled");
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return res;
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}
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