PR: 1751

Submitted by: David Woodhouse <dwmw2@infradead.org>
Approved by: steve@openssl.org

Compatibility patches for Cisco VPN client DTLS.

ssl/d1_both.c

@@ -300,7 +300,7 @@ int dtls1_do_write(SSL *s, int type)
 				const struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
 				int xlen;
 
-				if (frag_off == 0)
+				if (frag_off == 0 && s->version != DTLS1_BAD_VER)
 					{
 					/* reconstruct message header is if it
 					 * is being sent in single fragment */
@@ -407,8 +407,10 @@ long dtls1_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
 			s2n (msg_hdr->seq,p);
 			l2n3(0,p);
 			l2n3(msg_len,p);
+			if (s->version != DTLS1_BAD_VER) {
 				p       -= DTLS1_HM_HEADER_LENGTH;
 				msg_len += DTLS1_HM_HEADER_LENGTH;
+			}
 
 			ssl3_finish_mac(s, p, msg_len);
 			if (s->msg_callback)
@@ -775,6 +777,13 @@ int dtls1_send_change_cipher_spec(SSL *s, int a, int b)
 		*p++=SSL3_MT_CCS;
 		s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
 		s->init_num=DTLS1_CCS_HEADER_LENGTH;
+
+		if (s->version == DTLS1_BAD_VER) {
+			s->d1->next_handshake_write_seq++;
+			s2n(s->d1->handshake_write_seq,p);
+			s->init_num+=2;
+		}
+
 		s->init_off=0;
 
 		dtls1_set_message_header_int(s, SSL3_MT_CCS, 0, 
@@ -989,7 +998,7 @@ dtls1_buffer_message(SSL *s, int is_ccs)
 	if ( is_ccs)
 		{
 		OPENSSL_assert(s->d1->w_msg_hdr.msg_len + 
-			DTLS1_CCS_HEADER_LENGTH == (unsigned int)s->init_num);
+			       ((s->version==DTLS1_VERSION)?DTLS1_CCS_HEADER_LENGTH:3) == (unsigned int)s->init_num);
 		}
 	else
 		{

ssl/d1_clnt.c

@@ -130,7 +130,7 @@ static int dtls1_get_hello_verify(SSL *s);
 
 static const SSL_METHOD *dtls1_get_client_method(int ver)
 	{
-	if (ver == DTLS1_VERSION)
+	if (ver == DTLS1_VERSION || ver == DTLS1_BAD_VER)
 		return(DTLSv1_client_method());
 	else
 		return(NULL);
@@ -181,7 +181,8 @@ int dtls1_connect(SSL *s)
 			s->server=0;
 			if (cb != NULL) cb(s,SSL_CB_HANDSHAKE_START,1);
 
-			if ((s->version & 0xff00 ) != (DTLS1_VERSION & 0xff00))
+			if ((s->version & 0xff00 ) != (DTLS1_VERSION & 0xff00) &&
+			    (s->version & 0xff00 ) != (DTLS1_BAD_VER & 0xff00))
 				{
 				SSLerr(SSL_F_DTLS1_CONNECT, ERR_R_INTERNAL_ERROR);
 				ret = -1;

ssl/d1_lib.c

@@ -176,6 +176,9 @@ void dtls1_free(SSL *s)
 void dtls1_clear(SSL *s)
 	{
 	ssl3_clear(s);
+	if (s->options & SSL_OP_CISCO_ANYCONNECT)
+		s->version=DTLS1_BAD_VER;
+	else
 		s->version=DTLS1_VERSION;
 	}
 

ssl/d1_pkt.c

@@ -591,7 +591,7 @@ again:
 				}
 			}
 
-		if ((version & 0xff00) != (DTLS1_VERSION & 0xff00))
+		if ((version & 0xff00) != (s->version & 0xff00))
 			{
 			SSLerr(SSL_F_DTLS1_GET_RECORD,SSL_R_WRONG_VERSION_NUMBER);
 			goto err;
@@ -1067,13 +1067,17 @@ start:
 	if (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC)
 		{
 		struct ccs_header_st ccs_hdr;
+		int ccs_hdr_len = DTLS1_CCS_HEADER_LENGTH;
 
 		dtls1_get_ccs_header(rr->data, &ccs_hdr);
 
+		if (s->version == DTLS1_BAD_VER)
+			ccs_hdr_len = 3;
+
 		/* 'Change Cipher Spec' is just a single byte, so we know
 		 * exactly what the record payload has to look like */
 		/* XDTLS: check that epoch is consistent */
-		if (	(rr->length != DTLS1_CCS_HEADER_LENGTH) || 
+		if (	(rr->length != ccs_hdr_len) || 
 			(rr->off != 0) || (rr->data[0] != SSL3_MT_CCS))
 			{
 			i=SSL_AD_ILLEGAL_PARAMETER;
@@ -1094,6 +1098,9 @@ start:
 		/* do this whenever CCS is processed */
 		dtls1_reset_seq_numbers(s, SSL3_CC_READ);
 
+		if (s->version == DTLS1_BAD_VER)
+			s->d1->handshake_read_seq++;
+
 		goto start;
 		}
 
@@ -1401,7 +1408,7 @@ int do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len,
 #if 0
 	/* 'create_empty_fragment' is true only when this function calls itself */
 	if (!clear && !create_empty_fragment && !s->s3->empty_fragment_done
-		&& SSL_version(s) != DTLS1_VERSION)
+	    && SSL_version(s) != DTLS1_VERSION && SSL_version(s) != DTLS1_BAD_VER)
 		{
 		/* countermeasure against known-IV weakness in CBC ciphersuites
 		 * (see http://www.openssl.org/~bodo/tls-cbc.txt) 
@@ -1428,7 +1435,6 @@ int do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len,
 		s->s3->empty_fragment_done = 1;
 		}
 #endif
-
 	p = wb->buf + prefix_len;
 
 	/* write the header */

ssl/d1_srvr.c

@@ -292,6 +292,7 @@ int dtls1_accept(SSL *s)
 			s->s3->tmp.next_state=SSL3_ST_SR_CLNT_HELLO_A;
 
 			/* HelloVerifyRequest resets Finished MAC */
+			if (s->version != DTLS1_BAD_VER)
 				ssl3_init_finished_mac(s);
 			break;
 			

ssl/dtls1.h

@@ -68,6 +68,7 @@ extern "C" {
 #endif
 
 #define DTLS1_VERSION			0xFEFF
+#define DTLS1_BAD_VER			0x0100
 
 #if 0
 /* this alert description is not specified anywhere... */

ssl/s3_clnt.c

@@ -737,7 +737,7 @@ int ssl3_get_server_hello(SSL *s)
 
 	if (!ok) return((int)n);
 
-	if ( SSL_version(s) == DTLS1_VERSION)
+	if ( SSL_version(s) == DTLS1_VERSION || SSL_version(s) == DTLS1_BAD_VER)
 		{
 		if ( s->s3->tmp.message_type == DTLS1_MT_HELLO_VERIFY_REQUEST)
 			{

ssl/s3_pkt.c

@@ -177,8 +177,8 @@ int ssl3_read_n(SSL *s, int n, int max, int extend)
 		}
 
 	/* extend reads should not span multiple packets for DTLS */
-	if ( SSL_version(s) == DTLS1_VERSION &&
+	if ( (SSL_version(s) == DTLS1_VERSION || SSL_version(s) == DTLS1_BAD_VER)
-		extend)
+	     &&	extend)
 		{
 		if ( left > 0 && n > left)
 			n = left;
@@ -836,7 +836,8 @@ int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
 			return(s->s3->wpend_ret);
 			}
 		else if (i <= 0) {
-			if (s->version == DTLS1_VERSION) {
+			if (s->version == DTLS1_VERSION ||
+			    s->version == DTLS1_BAD_VER) {
 				/* For DTLS, just drop it. That's kind of the whole
 				   point in using a datagram service */
 				wb->left = 0;

ssl/s3_srvr.c

@@ -1920,7 +1920,7 @@ int ssl3_get_client_key_exchange(SSL *s)
 			}
 
 		/* TLS and [incidentally] DTLS{0xFEFF} */
-		if (s->version > SSL3_VERSION)
+		if (s->version > SSL3_VERSION && s->version != DTLS1_BAD_VER)
 			{
 			n2s(p,i);
 			if (n != i+2)

ssl/ssl.h

@@ -542,6 +542,8 @@ typedef struct ssl_session_st
 #define SSL_OP_COOKIE_EXCHANGE              0x00002000L
 /* Don't use RFC4507 ticket extension */
 #define SSL_OP_NO_TICKET	            0x00004000L
+/* Use Cisco's "speshul" version of DTLS_BAD_VER (as client)  */
+#define SSL_OP_CISCO_ANYCONNECT		    0x00008000L
 
 /* As server, disallow session resumption on renegotiation */
 #define SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION	0x00010000L

ssl/ssl_lib.c

@@ -1038,7 +1038,8 @@ long SSL_ctrl(SSL *s,int cmd,long larg,void *parg)
 		s->max_cert_list=larg;
 		return(l);
 	case SSL_CTRL_SET_MTU:
-		if (SSL_version(s) == DTLS1_VERSION)
+		if (SSL_version(s) == DTLS1_VERSION ||
+		    SSL_version(s) == DTLS1_BAD_VER)
 			{
 			s->d1->mtu = larg;
 			return larg;

ssl/ssl_sess.c

@@ -300,6 +300,11 @@ int ssl_get_new_session(SSL *s, int session)
 			ss->ssl_version=TLS1_VERSION;
 			ss->session_id_length=SSL3_SSL_SESSION_ID_LENGTH;
 			}
+		else if (s->version == DTLS1_BAD_VER)
+			{
+			ss->ssl_version=DTLS1_BAD_VER;
+			ss->session_id_length=SSL3_SSL_SESSION_ID_LENGTH;
+			}
 		else if (s->version == DTLS1_VERSION)
 			{
 			ss->ssl_version=DTLS1_VERSION;

ssl/t1_enc.c

@@ -882,7 +882,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
 			mac_ctx = &hmac;
 		}
 
-	if (ssl->version == DTLS1_VERSION)
+	if (ssl->version == DTLS1_VERSION || ssl->version == DTLS1_BAD_VER)
 		{
 		unsigned char dtlsseq[8],*p=dtlsseq;
 
@@ -911,7 +911,7 @@ printf("rec=");
 {unsigned int z; for (z=0; z<rec->length; z++) printf("%02X ",buf[z]); printf("\n"); }
 #endif
 
-	if (ssl->version != DTLS1_VERSION)
+	if (ssl->version != DTLS1_VERSION && ssl->version != DTLS1_BAD_VER)
 		{
 		for (i=7; i>=0; i--)
 			{