Make ChangeCipherSpec compliant with DTLS RFC4347. From HEAD with a twist:

server interoperates with non-compliant pre-0.9.8f.

2 files changed, 37 insertions, 40 deletions

diff --git a/ssl/d1_both.c b/ssl/d1_both.c
index 7e6d300377..a17ebfa925 100644
--- a/ssl/d1_both.c
+++ b/ssl/d1_both.c
@@ -816,9 +816,14 @@ 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->d1->next_handshake_write_seq++;
-		s2n(s->d1->handshake_write_seq,p);
-
 		s->init_num=DTLS1_CCS_HEADER_LENGTH;
+
+		if (s->client_version == DTLS1_BAD_VER)
+			{
+			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, 
@@ -1056,7 +1061,7 @@ 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);
+            DTLS1_CCS_HEADER_LENGTH <= (unsigned int)s->init_num);
         }
     else
         {
@@ -1259,5 +1264,4 @@ dtls1_get_ccs_header(unsigned char *data, struct ccs_header_st *ccs_hdr)
     memset(ccs_hdr, 0x00, sizeof(struct ccs_header_st));
     
     ccs_hdr->type = *(data++);
-    n2s(data, ccs_hdr->seq);
 }
diff --git a/ssl/d1_pkt.c b/ssl/d1_pkt.c
index 24ef9ec3d2..333a26c0c2 100644
--- a/ssl/d1_pkt.c
+++ b/ssl/d1_pkt.c
@@ -974,47 +974,40 @@ start:
 		}
 
 	if (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC)
-        {
-        struct ccs_header_st ccs_hdr;
+		{
+		struct ccs_header_st ccs_hdr;
 
 		dtls1_get_ccs_header(rr->data, &ccs_hdr);
 
-		if ( ccs_hdr.seq == s->d1->handshake_read_seq)
-			{
-			/* '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) || 
-				(rr->off != 0) || (rr->data[0] != SSL3_MT_CCS))
-				{
-				i=SSL_AD_ILLEGAL_PARAMETER;
-				SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_BAD_CHANGE_CIPHER_SPEC);
-				goto err;
-				}
-			
-			rr->length=0;
-			
-			if (s->msg_callback)
-				s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC, 
-					rr->data, 1, s, s->msg_callback_arg);
-			
-			s->s3->change_cipher_spec=1;
-			if (!ssl3_do_change_cipher_spec(s))
-				goto err;
-			
-			/* do this whenever CCS is processed */
-			dtls1_reset_seq_numbers(s, SSL3_CC_READ);
-			
-			/* handshake read seq is reset upon handshake completion */
-			s->d1->handshake_read_seq++;
-			
-			goto start;
-			}
-		else
+		/* '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 (	(s->client_version == DTLS1_BAD_VER && rr->length != 3) ||
+			(s->client_version != DTLS1_BAD_VER && rr->length != DTLS1_CCS_HEADER_LENGTH) || 
+			(rr->off != 0) || (rr->data[0] != SSL3_MT_CCS))
 			{
-			rr->length = 0;
-			goto start;
+			i=SSL_AD_ILLEGAL_PARAMETER;
+			SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_BAD_CHANGE_CIPHER_SPEC);
+			goto err;
 			}
+
+		rr->length=0;
+
+		if (s->msg_callback)
+			s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC, 
+				rr->data, 1, s, s->msg_callback_arg);
+
+		s->s3->change_cipher_spec=1;
+		if (!ssl3_do_change_cipher_spec(s))
+			goto err;
+
+		/* do this whenever CCS is processed */
+		dtls1_reset_seq_numbers(s, SSL3_CC_READ);
+
+		/* handshake read seq is reset upon handshake completion */
+		s->d1->handshake_read_seq++;
+
+		goto start;
 		}
 
 	/* Unexpected handshake message (Client Hello, or protocol violation) */