https://origsvn.digium.com/svn/asterisk/branches/1.8 ........ r321392 | rmudgett | 2011-05-27 18:45:41 -0500 (Fri, 27 May 2011) | 12 lines Crash when using hagi and no servers are available. When none of the servers returned by the SRV querey respond, asterisk crashes. The problem is that if the loop over all the SRV entries finishes then the srv_context has already been cleaned up. * Make ast_srv_cleanup() check to see if the context is already cleaned up. (closes issue #19256) Reported by: byronclark ........ git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@321393 65c4cc65-6c06-0410-ace0-fbb531ad65f3
333 lines
7.9 KiB
C
333 lines
7.9 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 1999 - 2005, Digium, Inc.
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*
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* Mark Spencer <markster@digium.com>
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*
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* Funding provided by nic.at
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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 DNS SRV Record Lookup Support for Asterisk
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*
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* \author Mark Spencer <markster@digium.com>
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*
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* \arg See also \ref AstENUM
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*
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* \note Funding provided by nic.at
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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 <netinet/in.h>
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#include <arpa/nameser.h>
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#ifdef __APPLE__
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#if __APPLE_CC__ >= 1495
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#include <arpa/nameser_compat.h>
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#endif
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#endif
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#include <resolv.h>
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#include "asterisk/channel.h"
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#include "asterisk/srv.h"
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#include "asterisk/dns.h"
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#include "asterisk/utils.h"
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#include "asterisk/linkedlists.h"
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#ifdef __APPLE__
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#undef T_SRV
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#define T_SRV 33
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#endif
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struct srv_entry {
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unsigned short priority;
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unsigned short weight;
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unsigned short port;
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unsigned int weight_sum;
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AST_LIST_ENTRY(srv_entry) list;
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char host[1];
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};
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struct srv_context {
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unsigned int have_weights:1;
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struct srv_entry *prev;
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unsigned int num_records;
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AST_LIST_HEAD_NOLOCK(srv_entries, srv_entry) entries;
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};
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static int parse_srv(unsigned char *answer, int len, unsigned char *msg, struct srv_entry **result)
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{
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struct srv {
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unsigned short priority;
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unsigned short weight;
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unsigned short port;
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} __attribute__((__packed__)) *srv = (struct srv *) answer;
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int res = 0;
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char repl[256] = "";
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struct srv_entry *entry;
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if (len < sizeof(*srv))
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return -1;
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answer += sizeof(*srv);
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len -= sizeof(*srv);
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if ((res = dn_expand(msg, answer + len, answer, repl, sizeof(repl) - 1)) <= 0) {
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ast_log(LOG_WARNING, "Failed to expand hostname\n");
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return -1;
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}
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/* the magic value "." for the target domain means that this service
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is *NOT* available at the domain we searched */
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if (!strcmp(repl, "."))
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return -1;
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if (!(entry = ast_calloc(1, sizeof(*entry) + strlen(repl))))
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return -1;
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entry->priority = ntohs(srv->priority);
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entry->weight = ntohs(srv->weight);
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entry->port = ntohs(srv->port);
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strcpy(entry->host, repl);
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*result = entry;
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return 0;
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}
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static int srv_callback(void *context, unsigned char *answer, int len, unsigned char *fullanswer)
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{
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struct srv_context *c = (struct srv_context *) context;
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struct srv_entry *entry = NULL;
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struct srv_entry *current;
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if (parse_srv(answer, len, fullanswer, &entry))
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return -1;
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if (entry->weight)
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c->have_weights = 1;
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AST_LIST_TRAVERSE_SAFE_BEGIN(&c->entries, current, list) {
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/* insert this entry just before the first existing
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entry with a higher priority */
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if (current->priority <= entry->priority)
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continue;
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AST_LIST_INSERT_BEFORE_CURRENT(entry, list);
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entry = NULL;
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break;
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}
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AST_LIST_TRAVERSE_SAFE_END;
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/* if we didn't find a place to insert the entry before an existing
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entry, then just add it to the end */
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if (entry)
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AST_LIST_INSERT_TAIL(&c->entries, entry, list);
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return 0;
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}
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/* Do the bizarre SRV record weight-handling algorithm
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involving sorting and random number generation...
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See RFC 2782 if you want know why this code does this
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*/
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static void process_weights(struct srv_context *context)
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{
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struct srv_entry *current;
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struct srv_entries newlist = AST_LIST_HEAD_NOLOCK_INIT_VALUE;
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while (AST_LIST_FIRST(&context->entries)) {
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unsigned int random_weight;
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unsigned int weight_sum;
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unsigned short cur_priority = AST_LIST_FIRST(&context->entries)->priority;
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struct srv_entries temp_list = AST_LIST_HEAD_NOLOCK_INIT_VALUE;
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weight_sum = 0;
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AST_LIST_TRAVERSE_SAFE_BEGIN(&context->entries, current, list) {
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if (current->priority != cur_priority)
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break;
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AST_LIST_MOVE_CURRENT(&temp_list, list);
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}
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AST_LIST_TRAVERSE_SAFE_END;
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while (AST_LIST_FIRST(&temp_list)) {
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weight_sum = 0;
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AST_LIST_TRAVERSE(&temp_list, current, list)
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current->weight_sum = weight_sum += current->weight;
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/* if all the remaining entries have weight == 0,
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then just append them to the result list and quit */
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if (weight_sum == 0) {
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AST_LIST_APPEND_LIST(&newlist, &temp_list, list);
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break;
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}
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random_weight = 1 + (unsigned int) ((float) weight_sum * (ast_random() / ((float) RAND_MAX + 1.0)));
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AST_LIST_TRAVERSE_SAFE_BEGIN(&temp_list, current, list) {
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if (current->weight < random_weight)
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continue;
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AST_LIST_MOVE_CURRENT(&newlist, list);
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break;
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}
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AST_LIST_TRAVERSE_SAFE_END;
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}
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}
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/* now that the new list has been ordered,
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put it in place */
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AST_LIST_APPEND_LIST(&context->entries, &newlist, list);
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}
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int ast_srv_lookup(struct srv_context **context, const char *service, const char **host, unsigned short *port)
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{
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struct srv_entry *cur;
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if (*context == NULL) {
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if (!(*context = ast_calloc(1, sizeof(struct srv_context)))) {
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return -1;
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}
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AST_LIST_HEAD_INIT_NOLOCK(&(*context)->entries);
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if ((ast_search_dns(*context, service, C_IN, T_SRV, srv_callback)) < 0) {
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ast_free(*context);
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*context = NULL;
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return -1;
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}
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if ((*context)->have_weights) {
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process_weights(*context);
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}
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(*context)->prev = AST_LIST_FIRST(&(*context)->entries);
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*host = (*context)->prev->host;
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*port = (*context)->prev->port;
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AST_LIST_TRAVERSE(&(*context)->entries, cur, list) {
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++((*context)->num_records);
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}
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return 0;
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}
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if (((*context)->prev = AST_LIST_NEXT((*context)->prev, list))) {
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/* Retrieve next item in result */
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*host = (*context)->prev->host;
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*port = (*context)->prev->port;
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return 0;
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} else {
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/* No more results */
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while ((cur = AST_LIST_REMOVE_HEAD(&(*context)->entries, list))) {
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ast_free(cur);
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}
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ast_free(*context);
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*context = NULL;
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return 1;
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}
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}
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void ast_srv_cleanup(struct srv_context **context)
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{
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const char *host;
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unsigned short port;
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if (*context) {
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/* We have a context to clean up. */
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while (!(ast_srv_lookup(context, NULL, &host, &port))) {
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}
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}
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}
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int ast_get_srv(struct ast_channel *chan, char *host, int hostlen, int *port, const char *service)
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{
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struct srv_context context = { .entries = AST_LIST_HEAD_NOLOCK_INIT_VALUE };
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struct srv_entry *current;
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int ret;
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if (chan && ast_autoservice_start(chan) < 0) {
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return -1;
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}
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ret = ast_search_dns(&context, service, C_IN, T_SRV, srv_callback);
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if (context.have_weights) {
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process_weights(&context);
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}
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if (chan) {
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ret |= ast_autoservice_stop(chan);
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}
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/* TODO: there could be a "." entry in the returned list of
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answers... if so, this requires special handling */
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/* the list of entries will be sorted in the proper selection order
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already, so we just need the first one (if any) */
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if ((ret > 0) && (current = AST_LIST_REMOVE_HEAD(&context.entries, list))) {
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ast_copy_string(host, current->host, hostlen);
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*port = current->port;
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ast_free(current);
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ast_verb(4, "ast_get_srv: SRV lookup for '%s' mapped to host %s, port %d\n",
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service, host, *port);
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} else {
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host[0] = '\0';
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*port = -1;
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}
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while ((current = AST_LIST_REMOVE_HEAD(&context.entries, list))) {
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ast_free(current);
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}
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return ret;
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}
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unsigned int ast_srv_get_record_count(struct srv_context *context)
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{
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return context->num_records;
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}
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int ast_srv_get_nth_record(struct srv_context *context, int record_num, const char **host,
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unsigned short *port, unsigned short *priority, unsigned short *weight)
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{
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int i = 1;
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int res = -1;
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struct srv_entry *entry;
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if (record_num < 1 || record_num > context->num_records) {
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return res;
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}
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AST_LIST_TRAVERSE(&context->entries, entry, list) {
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if (i == record_num) {
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*host = entry->host;
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*port = entry->port;
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*priority = entry->priority;
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*weight = entry->weight;
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res = 0;
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break;
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}
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++i;
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}
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return res;
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}
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