res_rtp_asterisk: Automatically refresh stunaddr from DNS
This allows the STUN server to change its IP address without having to reload the res_rtp_asterisk module. The refresh of the name resolution occurs first when the module is loaded, then recurringly, slightly after the previous DNS answer TTL expires. ASTERISK-29508 #close Change-Id: I7955a046293f913ba121bbd82153b04439e3465f
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220ce865db
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166556961b
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@ -63,7 +63,8 @@ rtpend=20000
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; Hostname or address for the STUN server used when determining the external
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; IP address and port an RTP session can be reached at. The port number is
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; optional. If omitted the default value of 3478 will be used. This option is
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; disabled by default.
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; disabled by default. Name resolution will occur at load time, and if DNS is
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; used, name resolution will occur repeatedly after the TTL expires.
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;
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; e.g. stundaddr=mystun.server.com:3478
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;
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@ -0,0 +1,6 @@
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Subject: res_rtp_asterisk
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When the address of the STUN server (stunaddr) is a name resolved via DNS, the
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stunaddr will be recurringly resolved when the DNS answer Time-To-Live (TTL)
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expires. This allows the STUN server to change its IP address without having to
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reload the res_rtp_asterisk module.
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@ -39,6 +39,11 @@
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#include <arpa/nameser.h>
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/* \brief Delay between TTL expiration and the next DNS query, to make sure the
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resolver cache really expired. */
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#define EXTRA_TTL 2
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#define MAX_TTL ((INT_MAX - EXTRA_TTL) / 1000)
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/*! \brief Destructor for a DNS query */
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static void dns_query_recurring_destroy(void *data)
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{
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@ -91,10 +96,10 @@ static void dns_query_recurring_resolution_callback(const struct ast_dns_query *
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/* So.. if something has not externally cancelled this we can reschedule based on the TTL */
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if (!recurring->cancelled) {
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const struct ast_dns_result *result = ast_dns_query_get_result(query);
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int ttl = MIN(ast_dns_result_get_lowest_ttl(result), INT_MAX / 1000);
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int ttl = MIN(ast_dns_result_get_lowest_ttl(result), MAX_TTL);
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if (ttl) {
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recurring->timer = ast_sched_add(ast_dns_get_sched(), ttl * 1000, dns_query_recurring_scheduled_callback, ao2_bump(recurring));
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recurring->timer = ast_sched_add(ast_dns_get_sched(), (ttl + EXTRA_TTL) * 1000, dns_query_recurring_scheduled_callback, ao2_bump(recurring));
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if (recurring->timer < 0) {
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/* It is impossible for this to be the last reference as the query has a reference to it */
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ao2_ref(recurring, -1);
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@ -36,6 +36,11 @@
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#include "asterisk.h"
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#include <arpa/nameser.h>
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#include "asterisk/dns_core.h"
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#include "asterisk/dns_internal.h"
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#include "asterisk/dns_recurring.h"
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#include <sys/time.h>
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#include <signal.h>
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#include <fcntl.h>
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@ -230,6 +235,10 @@ static ast_rwlock_t ice_acl_lock = AST_RWLOCK_INIT_VALUE;
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static struct ast_acl_list *stun_acl = NULL;
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static ast_rwlock_t stun_acl_lock = AST_RWLOCK_INIT_VALUE;
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/*! stunaddr recurring resolution */
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static ast_rwlock_t stunaddr_lock = AST_RWLOCK_INIT_VALUE;
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static struct ast_dns_query_recurring *stunaddr_resolver = NULL;
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/*! \brief Pool factory used by pjlib to allocate memory. */
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static pj_caching_pool cachingpool;
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@ -646,6 +655,9 @@ static BIO_METHOD *dtls_bio_methods;
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static int __rtp_sendto(struct ast_rtp_instance *instance, void *buf, size_t size, int flags, struct ast_sockaddr *sa, int rtcp, int *via_ice, int use_srtp);
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static void stunaddr_resolve_callback(const struct ast_dns_query *query);
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static int store_stunaddr_resolved(const struct ast_dns_query *query);
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#if defined(HAVE_OPENSSL) && (OPENSSL_VERSION_NUMBER >= 0x10001000L) && !defined(OPENSSL_NO_SRTP)
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static int dtls_bio_new(BIO *bio)
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{
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@ -3529,6 +3541,7 @@ static void rtp_add_candidates_to_ice(struct ast_rtp_instance *instance, struct
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pj_sockaddr pjtmp;
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struct ast_ice_host_candidate *candidate;
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int af_inet_ok = 0, af_inet6_ok = 0;
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struct sockaddr_in stunaddr_copy;
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if (ast_sockaddr_is_ipv4(addr)) {
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af_inet_ok = 1;
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@ -3638,8 +3651,12 @@ static void rtp_add_candidates_to_ice(struct ast_rtp_instance *instance, struct
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freeifaddrs(ifa);
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}
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ast_rwlock_rdlock(&stunaddr_lock);
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memcpy(&stunaddr_copy, &stunaddr, sizeof(stunaddr));
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ast_rwlock_unlock(&stunaddr_lock);
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/* If configured to use a STUN server to get our external mapped address do so */
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if (stunaddr.sin_addr.s_addr && !stun_address_is_blacklisted(addr) &&
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if (stunaddr_copy.sin_addr.s_addr && !stun_address_is_blacklisted(addr) &&
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(ast_sockaddr_is_ipv4(addr) || ast_sockaddr_is_any(addr)) &&
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count < PJ_ICE_MAX_CAND) {
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struct sockaddr_in answer;
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@ -3656,7 +3673,7 @@ static void rtp_add_candidates_to_ice(struct ast_rtp_instance *instance, struct
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*/
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ao2_unlock(instance);
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rsp = ast_stun_request(component == AST_RTP_ICE_COMPONENT_RTCP
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? rtp->rtcp->s : rtp->s, &stunaddr, NULL, &answer);
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? rtp->rtcp->s : rtp->s, &stunaddr_copy, NULL, &answer);
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ao2_lock(instance);
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if (!rsp) {
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struct ast_rtp_engine_ice_candidate *candidate;
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@ -9009,6 +9026,72 @@ static int ast_rtp_bundle(struct ast_rtp_instance *child, struct ast_rtp_instanc
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return 0;
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}
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static void stunaddr_resolve_callback(const struct ast_dns_query *query)
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{
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const int lowest_ttl = ast_dns_result_get_lowest_ttl(ast_dns_query_get_result(query));
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const char *stunaddr_name = ast_dns_query_get_name(query);
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const char *stunaddr_resolved_str;
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if (!store_stunaddr_resolved(query)) {
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ast_log(LOG_WARNING, "Failed to resolve stunaddr '%s'. Cancelling recurring resolution.\n", stunaddr_name);
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return;
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}
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if (DEBUG_ATLEAST(2)) {
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ast_rwlock_rdlock(&stunaddr_lock);
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stunaddr_resolved_str = ast_inet_ntoa(stunaddr.sin_addr);
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ast_rwlock_unlock(&stunaddr_lock);
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ast_debug_stun(2, "Resolved stunaddr '%s' to '%s'. Lowest TTL = %d.\n",
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stunaddr_name,
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stunaddr_resolved_str,
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lowest_ttl);
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}
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if (!lowest_ttl) {
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ast_log(LOG_WARNING, "Resolution for stunaddr '%s' returned TTL = 0. Recurring resolution was cancelled.\n", ast_dns_query_get_name(query));
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}
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}
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static int store_stunaddr_resolved(const struct ast_dns_query *query)
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{
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const struct ast_dns_result *result = ast_dns_query_get_result(query);
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const struct ast_dns_record *record;
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for (record = ast_dns_result_get_records(result); record; record = ast_dns_record_get_next(record)) {
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const size_t data_size = ast_dns_record_get_data_size(record);
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const unsigned char *data = (unsigned char *)ast_dns_record_get_data(record);
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const int rr_type = ast_dns_record_get_rr_type(record);
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if (rr_type == ns_t_a && data_size == 4) {
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ast_rwlock_wrlock(&stunaddr_lock);
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memcpy(&stunaddr.sin_addr, data, data_size);
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stunaddr.sin_family = AF_INET;
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ast_rwlock_unlock(&stunaddr_lock);
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return 1;
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} else {
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ast_debug_stun(3, "Unrecognized rr_type '%u' or data_size '%zu' from DNS query for stunaddr '%s'\n",
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rr_type, data_size, ast_dns_query_get_name(query));
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continue;
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}
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}
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return 0;
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}
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static void clean_stunaddr(void) {
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if (stunaddr_resolver) {
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if (ast_dns_resolve_recurring_cancel(stunaddr_resolver)) {
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ast_log(LOG_ERROR, "Failed to cancel recurring DNS resolution of previous stunaddr.\n");
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}
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ao2_ref(stunaddr_resolver, -1);
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stunaddr_resolver = NULL;
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}
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ast_rwlock_wrlock(&stunaddr_lock);
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memset(&stunaddr, 0, sizeof(stunaddr));
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ast_rwlock_unlock(&stunaddr_lock);
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}
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#if defined(HAVE_OPENSSL) && (OPENSSL_VERSION_NUMBER >= 0x10001000L) && !defined(OPENSSL_NO_SRTP)
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/*! \pre instance is locked */
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static int ast_rtp_activate(struct ast_rtp_instance *instance)
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static char *handle_cli_rtp_settings(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
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{
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struct sockaddr_in stunaddr_copy;
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switch (cmd) {
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case CLI_INIT:
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e->command = "rtp show settings";
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@ -9138,6 +9222,11 @@ static char *handle_cli_rtp_settings(struct ast_cli_entry *e, int cmd, struct as
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ast_cli(a->fd, " Replay Protect: %s\n", AST_CLI_YESNO(srtp_replay_protection));
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#ifdef HAVE_PJPROJECT
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ast_cli(a->fd, " ICE support: %s\n", AST_CLI_YESNO(icesupport));
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ast_rwlock_rdlock(&stunaddr_lock);
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memcpy(&stunaddr_copy, &stunaddr, sizeof(stunaddr));
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ast_rwlock_unlock(&stunaddr_lock);
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ast_cli(a->fd, " STUN address: %s:%d\n", ast_inet_ntoa(stunaddr_copy.sin_addr), htons(stunaddr_copy.sin_port));
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#endif
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return CLI_SUCCESS;
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}
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@ -9386,7 +9475,7 @@ static int rtp_reload(int reload, int by_external_config)
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icesupport = DEFAULT_ICESUPPORT;
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stun_software_attribute = DEFAULT_STUN_SOFTWARE_ATTRIBUTE;
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turnport = DEFAULT_TURN_PORT;
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memset(&stunaddr, 0, sizeof(stunaddr));
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clean_stunaddr();
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turnaddr = pj_str(NULL);
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turnusername = pj_str(NULL);
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turnpassword = pj_str(NULL);
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@ -9464,9 +9553,35 @@ static int rtp_reload(int reload, int by_external_config)
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stun_software_attribute = ast_true(s);
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}
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if ((s = ast_variable_retrieve(cfg, "general", "stunaddr"))) {
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stunaddr.sin_port = htons(STANDARD_STUN_PORT);
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if (ast_parse_arg(s, PARSE_INADDR, &stunaddr)) {
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ast_log(LOG_WARNING, "Invalid STUN server address: %s\n", s);
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char *hostport, *host, *port;
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unsigned int port_parsed = STANDARD_STUN_PORT;
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struct ast_sockaddr stunaddr_parsed;
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hostport = ast_strdupa(s);
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if (!ast_parse_arg(hostport, PARSE_ADDR, &stunaddr_parsed)) {
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ast_debug_stun(3, "stunaddr = '%s' does not need name resolution\n",
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ast_sockaddr_stringify_host(&stunaddr_parsed));
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if (!ast_sockaddr_port(&stunaddr_parsed)) {
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ast_sockaddr_set_port(&stunaddr_parsed, STANDARD_STUN_PORT);
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}
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ast_rwlock_wrlock(&stunaddr_lock);
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ast_sockaddr_to_sin(&stunaddr_parsed, &stunaddr);
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ast_rwlock_unlock(&stunaddr_lock);
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} else if (ast_sockaddr_split_hostport(hostport, &host, &port, 0)) {
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if (port) {
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ast_parse_arg(port, PARSE_UINT32|PARSE_IN_RANGE, &port_parsed, 1, 65535);
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}
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stunaddr.sin_port = htons(port_parsed);
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stunaddr_resolver = ast_dns_resolve_recurring(host, T_A, C_IN,
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&stunaddr_resolve_callback, NULL);
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if (!stunaddr_resolver) {
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ast_log(LOG_ERROR, "Failed to setup recurring DNS resolution of stunaddr '%s'",
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host);
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}
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} else {
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ast_log(LOG_ERROR, "Failed to parse stunaddr '%s'", hostport);
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}
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}
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if ((s = ast_variable_retrieve(cfg, "general", "turnaddr"))) {
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acl_change_sub = stasis_unsubscribe_and_join(acl_change_sub);
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rtp_unload_acl(&ice_acl_lock, &ice_acl);
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rtp_unload_acl(&stun_acl_lock, &stun_acl);
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clean_stunaddr();
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#endif
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return 0;
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