DTLS didn't handle alerts correctly.

PR: 1632

ssl/d1_pkt.c

@@ -850,6 +850,14 @@ start:
              *  may be fragmented--don't always expect dest_maxlen bytes */
 			if ( rr->length < dest_maxlen)
 				{
+#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
+				/*
+				 * for normal alerts rr->length is 2, while
+				 * dest_maxlen is 7 if we were to handle this
+				 * non-existing alert...
+				 */
+				FIX ME
+#endif
 				s->rstate=SSL_ST_READ_HEADER;
 				rr->length = 0;
 				goto start;
@@ -1546,7 +1554,7 @@ int dtls1_dispatch_alert(SSL *s)
 	{
 	int i,j;
 	void (*cb)(const SSL *ssl,int type,int val)=NULL;
-	unsigned char buf[2 + 2 + 3]; /* alert level + alert desc + message seq +frag_off */
+	unsigned char buf[DTLS1_AL_HEADER_LENGTH];
 	unsigned char *ptr = &buf[0];
 
 	s->s3->alert_dispatch=0;

ssl/dtls1.h

@@ -70,6 +70,7 @@ extern "C" {
 #define DTLS1_VERSION			0xFEFF
 
 #if 0
+/* this alert description is not specified anywhere... */
 #define DTLS1_AD_MISSING_HANDSHAKE_MESSAGE    110
 #endif
 
@@ -85,7 +86,11 @@ extern "C" {
 
 #define DTLS1_CCS_HEADER_LENGTH                  1
 
+#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
 #define DTLS1_AL_HEADER_LENGTH                   7
+#else
+#define DTLS1_AL_HEADER_LENGTH                   2
+#endif
 
 
 typedef struct dtls1_bitmap_st