PR: 2756

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>

Fix DTLS timeout handling.

ssl/d1_lib.c

@@ -391,6 +391,7 @@ void dtls1_double_timeout(SSL *s)
 void dtls1_stop_timer(SSL *s)
 	{
 	/* Reset everything */
+	memset(&(s->d1->timeout), 0, sizeof(struct dtls1_timeout_st));
 	memset(&(s->d1->next_timeout), 0, sizeof(struct timeval));
 	s->d1->timeout_duration = 1;
 	BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, &(s->d1->next_timeout));
@@ -398,35 +399,43 @@ void dtls1_stop_timer(SSL *s)
 	dtls1_clear_record_buffer(s);
 	}
 
-int dtls1_handle_timeout(SSL *s)
+int dtls1_check_timeout_num(SSL *s)
 	{
-	DTLS1_STATE *state;
+	s->d1->timeout.num_alerts++;
 
-	/* if no timer is expired, don't do anything */
-	if (!dtls1_is_timer_expired(s))
+	/* Reduce MTU after 2 unsuccessful retransmissions */
+	if (s->d1->timeout.num_alerts > 2)
 		{
-		return 0;
+		s->d1->mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);		
 		}
 
-	dtls1_double_timeout(s);
-	state = s->d1;
-	state->timeout.num_alerts++;
-	if ( state->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT)
+	if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT)
 		{
 		/* fail the connection, enough alerts have been sent */
 		SSLerr(SSL_F_DTLS1_HANDLE_TIMEOUT,SSL_R_READ_TIMEOUT_EXPIRED);
 		return -1;
 		}
 
-	state->timeout.read_timeouts++;
-	if ( state->timeout.read_timeouts > DTLS1_TMO_READ_COUNT)
+	return 0;
+	}
+
+int dtls1_handle_timeout(SSL *s)
+	{
+	/* if no timer is expired, don't do anything */
+	if (!dtls1_is_timer_expired(s))
 		{
-		state->timeout.read_timeouts = 1;
+		return 0;
 		}
 
-	if (state->timeout_duration > 2)
+	dtls1_double_timeout(s);
+
+	if (dtls1_check_timeout_num(s) < 0)
+		return -1;
+
+	s->d1->timeout.read_timeouts++;
+	if (s->d1->timeout.read_timeouts > DTLS1_TMO_READ_COUNT)
 		{
-		s->d1->mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);		
+		s->d1->timeout.read_timeouts = 1;
 		}
 
 #ifndef OPENSSL_NO_HEARTBEATS

ssl/d1_pkt.c

@@ -179,7 +179,6 @@ static int dtls1_record_needs_buffering(SSL *s, SSL3_RECORD *rr,
 static int dtls1_buffer_record(SSL *s, record_pqueue *q,
 	unsigned char *priority);
 static int dtls1_process_record(SSL *s);
-static void dtls1_clear_timeouts(SSL *s);
 
 /* copy buffered record into SSL structure */
 static int
@@ -698,7 +697,6 @@ again:
 		goto again;   /* get another record */
 		}
 
-	dtls1_clear_timeouts(s);  /* done waiting */
 	return(1);
 
 	}
@@ -1250,6 +1248,9 @@ start:
 		 */
 		if (msg_hdr.type == SSL3_MT_FINISHED)
 			{
+			if (dtls1_check_timeout_num(s) < 0)
+				return -1;
+
 			dtls1_retransmit_buffered_messages(s);
 			rr->length = 0;
 			goto start;
@@ -1873,10 +1874,3 @@ dtls1_reset_seq_numbers(SSL *s, int rw)
 
 	memset(seq, 0x00, seq_bytes);
 	}
-
-
-static void
-dtls1_clear_timeouts(SSL *s)
-	{
-	memset(&(s->d1->timeout), 0x00, sizeof(struct dtls1_timeout_st));
-	}

ssl/ssl_locl.h

@@ -988,6 +988,7 @@ void dtls1_get_ccs_header(unsigned char *data, struct ccs_header_st *ccs_hdr);
 void dtls1_reset_seq_numbers(SSL *s, int rw);
 long dtls1_default_timeout(void);
 struct timeval* dtls1_get_timeout(SSL *s, struct timeval* timeleft);
+int dtls1_check_timeout_num(SSL *s);
 int dtls1_handle_timeout(SSL *s);
 const SSL_CIPHER *dtls1_get_cipher(unsigned int u);
 void dtls1_start_timer(SSL *s);