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res_rtp_asterisk: Add support for DTLS handshake retransmissions 

On congested networks, it is possible for the DTLS handshake messages to get
lost. This patch adds a timer to res_rtp_asterisk that will periodically
check to see if the handshake has succeeded. If not, it will retransmit the
DTLS handshake.

Review: https://reviewboard.asterisk.org/r/3337

ASTERISK-23649 #close
Reported by: Nitesh Bansal
patches:
  dtls_retransmission.patch uploaded by Nitesh Bansal (License 6418)
........

Merged revisions 413008 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 413009 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@413012 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Matthew Jordan 2014-04-25 19:26:14 +00:00
parent 798b21a914
commit bf81470083
1 changed files with 58 additions and 0 deletions
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58
res/res_rtp_asterisk.c
View File

@ -283,6 +283,7 @@ struct ast_rtp {
SSL *ssl; /*!< SSL session */
BIO *read_bio; /*!< Memory buffer for reading */
BIO *write_bio; /*!< Memory buffer for writing */
ast_mutex_t dtls_timer_lock; /*!< Lock for synchronization purposes */
enum ast_rtp_dtls_setup dtls_setup; /*!< Current setup state */
enum ast_srtp_suite suite; /*!< SRTP crypto suite */
char local_fingerprint[160]; /*!< Fingerprint of our certificate */
@ -291,6 +292,7 @@ struct ast_rtp {
unsigned int dtls_failure:1; /*!< Failure occurred during DTLS negotiation */
unsigned int rekey; /*!< Interval at which to renegotiate and rekey */
int rekeyid; /*!< Scheduled item id for rekeying */
int dtlstimerid; /*!< Scheduled item id for DTLS retransmission for RTP */
#endif
};
@ -402,6 +404,7 @@ static int ast_rtp_sendcng(struct ast_rtp_instance *instance, int level);
#ifdef HAVE_OPENSSL_SRTP
static int ast_rtp_activate(struct ast_rtp_instance *instance);
static void dtls_srtp_check_pending(struct ast_rtp_instance *instance, struct ast_rtp *rtp);
#endif
static int __rtp_sendto(struct ast_rtp_instance *instance, void *buf, size_t size, int flags, struct ast_sockaddr *sa, int rtcp, int *ice, int use_srtp);
@ -1320,9 +1323,43 @@ static inline int rtcp_debug_test_addr(struct ast_sockaddr *addr)
}
#ifdef HAVE_OPENSSL_SRTP
static int dtls_srtp_handle_timeout(const void *data)
{
struct ast_rtp_instance *instance = (struct ast_rtp_instance *)data;
struct ast_rtp *rtp = ast_rtp_instance_get_data(instance);
if (!rtp)
{
return 0;
}
ast_mutex_lock(&rtp->dtls_timer_lock);
if (rtp->dtlstimerid == -1)
{
ast_mutex_unlock(&rtp->dtls_timer_lock);
ao2_ref(instance, -1);
return 0;
}
rtp->dtlstimerid = -1;
ast_mutex_unlock(&rtp->dtls_timer_lock);
if (rtp->ssl) {
DTLSv1_handle_timeout(rtp->ssl);
}
dtls_srtp_check_pending(instance, rtp);
ao2_ref(instance, -1);
return 0;
}
static void dtls_srtp_check_pending(struct ast_rtp_instance *instance, struct ast_rtp *rtp)
{
size_t pending = BIO_ctrl_pending(rtp->write_bio);
struct timeval dtls_timeout; /* timeout on DTLS */
if (pending > 0) {
char outgoing[pending];
@ -1339,6 +1376,23 @@ static void dtls_srtp_check_pending(struct ast_rtp_instance *instance, struct as
out = BIO_read(rtp->write_bio, outgoing, sizeof(outgoing));
/* Stop existing DTLS timer if running */
ast_mutex_lock(&rtp->dtls_timer_lock);
if (rtp->dtlstimerid > -1) {
AST_SCHED_DEL_UNREF(rtp->sched, rtp->dtlstimerid, ao2_ref(instance, -1));
rtp->dtlstimerid = -1;
}
if (DTLSv1_get_timeout(rtp->ssl, &dtls_timeout)) {
int timeout = dtls_timeout.tv_sec * 1000 + dtls_timeout.tv_usec / 1000;
ao2_ref(instance, +1);
if ((rtp->dtlstimerid = ast_sched_add(rtp->sched, timeout, dtls_srtp_handle_timeout, instance)) < 0) {
ao2_ref(instance, -1);
ast_log(LOG_WARNING, "scheduling DTLS retransmission for RTP instance [%p] failed.\n", instance);
}
}
ast_mutex_unlock(&rtp->dtls_timer_lock);
__rtp_sendto(instance, outgoing, out, 0, &remote_address, 0, &ice, 0);
}
}
@ -1972,6 +2026,7 @@ static int ast_rtp_new(struct ast_rtp_instance *instance,
#ifdef HAVE_OPENSSL_SRTP
rtp->rekeyid = -1;
rtp->dtlstimerid = -1;
#endif
return 0;
@ -4319,6 +4374,9 @@ static void ast_rtp_stop(struct ast_rtp_instance *instance)
#ifdef HAVE_OPENSSL_SRTP
AST_SCHED_DEL_UNREF(rtp->sched, rtp->rekeyid, ao2_ref(instance, -1));
ast_mutex_lock(&rtp->dtls_timer_lock);
AST_SCHED_DEL_UNREF(rtp->sched, rtp->dtlstimerid, ao2_ref(instance, -1));
ast_mutex_unlock(&rtp->dtls_timer_lock);
#endif
if (rtp->rtcp && rtp->rtcp->schedid > 0) {