PR: 2658

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

Support for TLS/DTLS heartbeats.

Author: snhenson

CHANGES

@@ -255,6 +255,9 @@
 
  Changes between 1.0.0f and 1.0.1  [xx XXX xxxx]
 
+  *) Add support for TLS/DTLS heartbeats.
+     [Robin Seggelmann <seggelmann@fh-muenster.de>]
+
   *) Improved PRNG seeding for VOS.
      [Paul Green <Paul.Green@stratus.com>]
 

apps/s_cb.c

@@ -603,6 +603,26 @@ void MS_CALLBACK msg_cb(int write_p, int version, int content_type, const void *
 					}
 				}
 			}
+
+#ifndef OPENSSL_NO_HEARTBEATS
+		if (content_type == 24) /* Heartbeat */
+			{
+			str_details1 = ", Heartbeat";
+			
+			if (len > 0)
+				{
+				switch (((const unsigned char*)buf)[0])
+					{
+				case 1:
+					str_details1 = ", HeartbeatRequest";
+					break;
+				case 2:
+					str_details1 = ", HeartbeatResponse";
+					break;
+					}
+				}
+			}
+#endif
 		}
 
 	BIO_printf(bio, "%s %s%s [length %04lx]%s%s\n", str_write_p, str_version, str_content_type, (unsigned long)len, str_details1, str_details2);

apps/s_client.c

@@ -1862,6 +1862,14 @@ printf("read=%d pending=%d peek=%d\n",k,SSL_pending(con),SSL_peek(con,zbuf,10240
 				SSL_renegotiate(con);
 				cbuf_len=0;
 				}
+#ifndef OPENSSL_NO_HEARTBEATS
+			else if ((!c_ign_eof) && (cbuf[0] == 'B'))
+ 				{
+				BIO_printf(bio_err,"HEARTBEATING\n");
+				SSL_heartbeat(con);
+				cbuf_len=0;
+				}
+#endif
 			else
 				{
 				cbuf_len=i;

apps/s_server.c

@@ -2222,6 +2222,16 @@ static int sv_body(char *hostname, int s, unsigned char *context)
 					goto err;
 					}
 
+#ifndef OPENSSL_NO_HEARTBEATS
+				if ((buf[0] == 'B') &&
+					((buf[1] == '\n') || (buf[1] == '\r')))
+					{
+					BIO_printf(bio_err,"HEARTBEATING\n");
+					SSL_heartbeat(con);
+					i=0;
+					continue;
+					}
+#endif
 				if ((buf[0] == 'r') && 
 					((buf[1] == '\n') || (buf[1] == '\r')))
 					{

ssl/d1_both.c

@@ -1084,7 +1084,11 @@ int dtls1_read_failed(SSL *s, int code)
 		return code;
 		}
 
-	if ( ! SSL_in_init(s))  /* done, no need to send a retransmit */
+#ifndef OPENSSL_NO_HEARTBEATS
+	if (!SSL_in_init(s) && !s->tlsext_hb_pending)  /* done, no need to send a retransmit */
+#else
+	if (!SSL_in_init(s))  /* done, no need to send a retransmit */
+#endif
 		{
 		BIO_set_flags(SSL_get_rbio(s), BIO_FLAGS_READ);
 		return code;
@@ -1438,3 +1442,149 @@ int dtls1_shutdown(SSL *s)
 #endif
 	return ret;
 	}
+
+#ifndef OPENSSL_NO_HEARTBEATS
+int
+dtls1_process_heartbeat(SSL *s)
+	{
+	unsigned char *p = &s->s3->rrec.data[0], *pl;
+	unsigned short hbtype;
+	unsigned int payload;
+	unsigned int padding = 16; /* Use minimum padding */
+
+	/* Read type and payload length first */
+	hbtype = *p++;
+	n2s(p, payload);
+	pl = p;
+
+	if (s->msg_callback)
+		s->msg_callback(0, s->version, TLS1_RT_HEARTBEAT,
+			&s->s3->rrec.data[0], s->s3->rrec.length,
+			s, s->msg_callback_arg);
+
+	if (hbtype == TLS1_HB_REQUEST)
+		{
+		unsigned char *buffer, *bp;
+		int r;
+
+		/* Allocate memory for the response, size is 1 byte
+		 * message type, plus 2 bytes payload length, plus
+		 * payload, plus padding
+		 */
+		buffer = OPENSSL_malloc(1 + 2 + payload + padding);
+		bp = buffer;
+
+		/* Enter response type, length and copy payload */
+		*bp++ = TLS1_HB_RESPONSE;
+		s2n(payload, bp);
+		memcpy(bp, pl, payload);
+		/* Random padding */
+		RAND_pseudo_bytes(p, padding);
+
+		r = dtls1_write_bytes(s, TLS1_RT_HEARTBEAT, buffer, 3 + payload + padding);
+
+		if (r >= 0 && s->msg_callback)
+			s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
+				buffer, 3 + payload + padding,
+				s, s->msg_callback_arg);
+
+		OPENSSL_free(buffer);
+
+		if (r < 0)
+			return r;
+		}
+	else if (hbtype == TLS1_HB_RESPONSE)
+		{
+		unsigned int seq;
+
+		/* We only send sequence numbers (2 bytes unsigned int),
+		 * and 16 random bytes, so we just try to read the
+		 * sequence number */
+		n2s(pl, seq);
+
+		if (payload == 18 && seq == s->tlsext_hb_seq)
+			{
+			dtls1_stop_timer(s);
+			s->tlsext_hb_seq++;
+			s->tlsext_hb_pending = 0;
+			}
+		}
+
+	return 0;
+	}
+
+int
+dtls1_heartbeat(SSL *s)
+	{
+	unsigned char *buf, *p;
+	int ret;
+	unsigned int payload = 18; /* Sequence number + random bytes */
+	unsigned int padding = 16; /* Use minimum padding */
+
+	/* Only send if peer supports and accepts HB requests... */
+	if (!(s->tlsext_heartbeat & SSL_TLSEXT_HB_ENABLED) ||
+	    s->tlsext_heartbeat & SSL_TLSEXT_HB_DONT_SEND_REQUESTS)
+		{
+		SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_TLS_HEARTBEAT_PEER_DOESNT_ACCEPT);
+		return -1;
+		}
+
+	/* ...and there is none in flight yet... */
+	if (s->tlsext_hb_pending)
+		{
+		SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_TLS_HEARTBEAT_PENDING);
+		return -1;
+		}
+
+	/* ...and no handshake in progress. */
+	if (SSL_in_init(s) || s->in_handshake)
+		{
+		SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_UNEXPECTED_MESSAGE);
+		return -1;
+		}
+
+	/* Check if padding is too long, payload and padding
+	 * must not exceed 2^14 - 3 = 16381 bytes in total.
+	 */
+	OPENSSL_assert(payload + padding <= 16381);
+
+	/* Create HeartBeat message, we just use a sequence number
+	 * as payload to distuingish different messages and add
+	 * some random stuff.
+	 *  - Message Type, 1 byte
+	 *  - Payload Length, 2 bytes (unsigned int)
+	 *  - Payload, the sequence number (2 bytes uint)
+	 *  - Payload, random bytes (16 bytes uint)
+	 *  - Padding
+	 */
+	buf = OPENSSL_malloc(1 + 2 + payload + padding);
+	p = buf;
+	/* Message Type */
+	*p++ = TLS1_HB_REQUEST;
+	/* Payload length (18 bytes here) */
+	s2n(payload, p);
+	/* Sequence number */
+	s2n(s->tlsext_hb_seq, p);
+	/* 16 random bytes */
+	RAND_pseudo_bytes(p, 16);
+	p += 16;
+	/* Random padding */
+	RAND_pseudo_bytes(p, padding);
+
+	ret = dtls1_write_bytes(s, TLS1_RT_HEARTBEAT, buf, 3 + payload + padding);
+	if (ret >= 0)
+		{
+		if (s->msg_callback)
+			s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
+				buf, 3 + payload + padding,
+				s, s->msg_callback_arg);
+
+		dtls1_start_timer(s);
+		s->tlsext_hb_pending = 1;
+		}
+
+	OPENSSL_free(buf);
+
+	return ret;
+	}
+#endif

ssl/d1_clnt.c

@@ -177,6 +177,19 @@ int dtls1_connect(SSL *s)
 	BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE, s->in_handshake, NULL);
 #endif
 
+#ifndef OPENSSL_NO_HEARTBEATS
+	/* If we're awaiting a HeartbeatResponse, pretend we
+	 * already got and don't await it anymore, because
+	 * Heartbeats don't make sense during handshakes anyway.
+	 */
+	if (s->tlsext_hb_pending)
+		{
+		dtls1_stop_timer(s);
+		s->tlsext_hb_pending = 0;
+		s->tlsext_hb_seq++;
+		}
+#endif
+
 	for (;;)
 		{
 		state=s->state;

ssl/d1_lib.c

@@ -424,6 +424,14 @@ int dtls1_handle_timeout(SSL *s)
 		state->timeout.read_timeouts = 1;
 		}
 
+#ifndef OPENSSL_NO_HEARTBEATS
+	if (s->tlsext_hb_pending)
+		{
+		s->tlsext_hb_pending = 0;
+		return dtls1_heartbeat(s);
+		}
+#endif
+
 	dtls1_start_timer(s);
 	return dtls1_retransmit_buffered_messages(s);
 	}

ssl/d1_pkt.c

@@ -937,6 +937,19 @@ int dtls1_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek)
 			dest = s->d1->alert_fragment;
 			dest_len = &s->d1->alert_fragment_len;
 			}
+#ifndef OPENSSL_NO_HEARTBEATS
+		else if (rr->type == TLS1_RT_HEARTBEAT)
+			{
+			dtls1_process_heartbeat(s);
+
+			/* Exit and notify application to read again */
+			rr->length = 0;
+			s->rwstate=SSL_READING;
+			BIO_clear_retry_flags(SSL_get_rbio(s));
+			BIO_set_retry_read(SSL_get_rbio(s));
+			return(-1);
+			}
+#endif
 		/* else it's a CCS message, or application data or wrong */
 		else if (rr->type != SSL3_RT_CHANGE_CIPHER_SPEC)
 			{

ssl/d1_srvr.c

@@ -186,6 +186,19 @@ int dtls1_accept(SSL *s)
 		return(-1);
 		}
 
+#ifndef OPENSSL_NO_HEARTBEATS
+	/* If we're awaiting a HeartbeatResponse, pretend we
+	 * already got and don't await it anymore, because
+	 * Heartbeats don't make sense during handshakes anyway.
+	 */
+	if (s->tlsext_hb_pending)
+		{
+		dtls1_stop_timer(s);
+		s->tlsext_hb_pending = 0;
+		s->tlsext_hb_seq++;
+		}
+#endif
+
 	for (;;)
 		{
 		state=s->state;

ssl/dtls1.h

@@ -236,7 +236,7 @@ typedef struct dtls1_state_st
 
 	struct dtls1_timeout_st timeout;
 
-	/* Indicates when the last handshake msg sent will timeout */
+	/* Indicates when the last handshake msg or heartbeat sent will timeout */
 	struct timeval next_timeout;
 
 	/* Timeout duration */