d1_pkt.c

mediastreamer2是开源的网络传输媒体流的库

#endif

	p = wb->buf + prefix_len;

	/* write the header */

	*(p++)=type&0xff;
	wr->type=type;

	*(p++)=(s->version>>8);
	*(p++)=s->version&0xff;

	/* field where we are to write out packet epoch, seq num and len */
	pseq=p; 
	p+=10;

	/* lets setup the record stuff. */

	/* Make space for the explicit IV in case of CBC.
	 * (this is a bit of a boundary violation, but what the heck).
	 */
	if ( s->enc_write_ctx && 
		(EVP_CIPHER_mode( s->enc_write_ctx->cipher ) & EVP_CIPH_CBC_MODE))
		bs = EVP_CIPHER_block_size(s->enc_write_ctx->cipher);
	else
		bs = 0;

	wr->data=p + bs;  /* make room for IV in case of CBC */
	wr->length=(int)len;
	wr->input=(unsigned char *)buf;

	/* we now 'read' from wr->input, wr->length bytes into
	 * wr->data */

	/* first we compress */
	if (s->compress != NULL)
		{
		if (!ssl3_do_compress(s))
			{
			SSLerr(SSL_F_DO_DTLS1_WRITE,SSL_R_COMPRESSION_FAILURE);
			goto err;
			}
		}
	else
		{
		memcpy(wr->data,wr->input,wr->length);
		wr->input=wr->data;
		}

	/* we should still have the output to wr->data and the input
	 * from wr->input.  Length should be wr->length.
	 * wr->data still points in the wb->buf */

	if (mac_size != 0)
		{
		s->method->ssl3_enc->mac(s,&(p[wr->length + bs]),1);
		wr->length+=mac_size;
		}

	/* this is true regardless of mac size */
	wr->input=p;
	wr->data=p;


	/* ssl3_enc can only have an error on read */
	wr->length += bs;  /* bs != 0 in case of CBC.  The enc fn provides
						* the randomness */ 
	s->method->ssl3_enc->enc(s,1);

	/* record length after mac and block padding */
/*	if (type == SSL3_RT_APPLICATION_DATA ||
	(type == SSL3_RT_ALERT && ! SSL_in_init(s))) */
	
	/* there's only one epoch between handshake and app data */
	
	s2n(s->d1->w_epoch, pseq);

	/* XDTLS: ?? */
/*	else
	s2n(s->d1->handshake_epoch, pseq); */

	memcpy(pseq, &(s->s3->write_sequence[2]), 6);
	pseq+=6;
	s2n(wr->length,pseq);

	/* we should now have
	 * wr->data pointing to the encrypted data, which is
	 * wr->length long */
	wr->type=type; /* not needed but helps for debugging */
	wr->length+=DTLS1_RT_HEADER_LENGTH;

#if 0  /* this is now done at the message layer */
	/* buffer the record, making it easy to handle retransmits */
	if ( type == SSL3_RT_HANDSHAKE || type == SSL3_RT_CHANGE_CIPHER_SPEC)
		dtls1_buffer_record(s, wr->data, wr->length, 
			*((PQ_64BIT *)&(s->s3->write_sequence[0])));
#endif

	ssl3_record_sequence_update(&(s->s3->write_sequence[0]));

	if (create_empty_fragment)
		{
		/* we are in a recursive call;
		 * just return the length, don't write out anything here
		 */
		return wr->length;
		}

	/* now let's set up wb */
	wb->left = prefix_len + wr->length;
	wb->offset = 0;

	/* memorize arguments so that ssl3_write_pending can detect bad write retries later */
	s->s3->wpend_tot=len;
	s->s3->wpend_buf=buf;
	s->s3->wpend_type=type;
	s->s3->wpend_ret=len;

	/* we now just need to write the buffer */
	return ssl3_write_pending(s,type,buf,len);
err:
	return -1;
	}



static int dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap,
	PQ_64BIT *seq_num)
	{
#if PQ_64BIT_IS_INTEGER
	PQ_64BIT mask = 0x0000000000000001L;
#endif
	PQ_64BIT rcd_num, tmp;

	pq_64bit_init(&rcd_num);
	pq_64bit_init(&tmp);

	/* this is the sequence number for the record just read */
	pq_64bit_bin2num(&rcd_num, s->s3->read_sequence, 8);

	
	if (pq_64bit_gt(&rcd_num, &(bitmap->max_seq_num)) ||
		pq_64bit_eq(&rcd_num, &(bitmap->max_seq_num)))
		{
		pq_64bit_assign(seq_num, &rcd_num);
		pq_64bit_free(&rcd_num);
		pq_64bit_free(&tmp);
		return 1;  /* this record is new */
		}

	pq_64bit_sub(&tmp, &(bitmap->max_seq_num), &rcd_num);

	if ( pq_64bit_get_word(&tmp) > bitmap->length)
		{
		pq_64bit_free(&rcd_num);
		pq_64bit_free(&tmp);
		return 0;  /* stale, outside the window */
		}

#if PQ_64BIT_IS_BIGNUM
	{
	int offset;
	pq_64bit_sub(&tmp, &(bitmap->max_seq_num), &rcd_num);
	pq_64bit_sub_word(&tmp, 1);
	offset = pq_64bit_get_word(&tmp);
	if ( pq_64bit_is_bit_set(&(bitmap->map), offset))
		{
		pq_64bit_free(&rcd_num);
		pq_64bit_free(&tmp);
		return 0;
		}
	}
#else
	mask <<= (bitmap->max_seq_num - rcd_num - 1);
	if (bitmap->map & mask)
		return 0; /* record previously received */
#endif
	
	pq_64bit_assign(seq_num, &rcd_num);
	pq_64bit_free(&rcd_num);
	pq_64bit_free(&tmp);
	return 1;
	}


static void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap)
	{
	unsigned int shift;
	PQ_64BIT rcd_num;
	PQ_64BIT tmp;
	PQ_64BIT_CTX *ctx;

	pq_64bit_init(&rcd_num);
	pq_64bit_init(&tmp);

	pq_64bit_bin2num(&rcd_num, s->s3->read_sequence, 8);

	/* unfortunate code complexity due to 64-bit manipulation support
	 * on 32-bit machines */
	if ( pq_64bit_gt(&rcd_num, &(bitmap->max_seq_num)) ||
		pq_64bit_eq(&rcd_num, &(bitmap->max_seq_num)))
		{
		pq_64bit_sub(&tmp, &rcd_num, &(bitmap->max_seq_num));
		pq_64bit_add_word(&tmp, 1);

		shift = (unsigned int)pq_64bit_get_word(&tmp);

		pq_64bit_lshift(&(tmp), &(bitmap->map), shift);
		pq_64bit_assign(&(bitmap->map), &tmp);

		pq_64bit_set_bit(&(bitmap->map), 0);
		pq_64bit_add_word(&rcd_num, 1);
		pq_64bit_assign(&(bitmap->max_seq_num), &rcd_num);

		pq_64bit_assign_word(&tmp, 1);
		pq_64bit_lshift(&tmp, &tmp, bitmap->length);
		ctx = pq_64bit_ctx_new(&ctx);
		pq_64bit_mod(&(bitmap->map), &(bitmap->map), &tmp, ctx);
		pq_64bit_ctx_free(ctx);
		}
	else
		{
		pq_64bit_sub(&tmp, &(bitmap->max_seq_num), &rcd_num);
		pq_64bit_sub_word(&tmp, 1);
		shift = (unsigned int)pq_64bit_get_word(&tmp);

		pq_64bit_set_bit(&(bitmap->map), shift);
		}

	pq_64bit_free(&rcd_num);
	pq_64bit_free(&tmp);
	}


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 *ptr = &buf[0];

	s->s3->alert_dispatch=0;

	memset(buf, 0x00, sizeof(buf));
	*ptr++ = s->s3->send_alert[0];
	*ptr++ = s->s3->send_alert[1];

	if (s->s3->send_alert[1] == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE)
		{	
		s2n(s->d1->handshake_read_seq, ptr);
#if 0
		if ( s->d1->r_msg_hdr.frag_off == 0)  /* waiting for a new msg */

		else
			s2n(s->d1->r_msg_hdr.seq, ptr); /* partial msg read */
#endif

#if 0
		fprintf(stderr, "s->d1->handshake_read_seq = %d, s->d1->r_msg_hdr.seq = %d\n",s->d1->handshake_read_seq,s->d1->r_msg_hdr.seq);
#endif
		l2n3(s->d1->r_msg_hdr.frag_off, ptr);
		}

	i = do_dtls1_write(s, SSL3_RT_ALERT, &buf[0], sizeof(buf), 0);
	if (i <= 0)
		{
		s->s3->alert_dispatch=1;
		/* fprintf( stderr, "not done with alert\n" ); */
		}
	else
		{
		if ( s->s3->send_alert[0] == SSL3_AL_FATAL ||
			s->s3->send_alert[1] == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE)
			(void)BIO_flush(s->wbio);

		if (s->msg_callback)
			s->msg_callback(1, s->version, SSL3_RT_ALERT, s->s3->send_alert, 
				2, s, s->msg_callback_arg);

		if (s->info_callback != NULL)
			cb=s->info_callback;
		else if (s->ctx->info_callback != NULL)
			cb=s->ctx->info_callback;

		if (cb != NULL)
			{
			j=(s->s3->send_alert[0]<<8)|s->s3->send_alert[1];
			cb(s,SSL_CB_WRITE_ALERT,j);
			}
		}
	return(i);
	}


static DTLS1_BITMAP *
dtls1_get_bitmap(SSL *s, SSL3_RECORD *rr, unsigned int *is_next_epoch)
    {
    
    *is_next_epoch = 0;

    /* In current epoch, accept HM, CCS, DATA, & ALERT */
    if (rr->epoch == s->d1->r_epoch)
        return &s->d1->bitmap;

    /* Only HM and ALERT messages can be from the next epoch */
    else if (rr->epoch == (unsigned long)(s->d1->r_epoch + 1) &&
        (rr->type == SSL3_RT_HANDSHAKE ||
            rr->type == SSL3_RT_ALERT))
        {
        *is_next_epoch = 1;
        return &s->d1->next_bitmap;
        }

    return NULL;
    }

#if 0
static int
dtls1_record_needs_buffering(SSL *s, SSL3_RECORD *rr, unsigned short *priority,
	unsigned long *offset)
	{

	/* alerts are passed up immediately */
	if ( rr->type == SSL3_RT_APPLICATION_DATA ||
		rr->type == SSL3_RT_ALERT)
		return 0;

	/* Only need to buffer if a handshake is underway.
	 * (this implies that Hello Request and Client Hello are passed up
	 * immediately) */
	if ( SSL_in_init(s))
		{
		unsigned char *data = rr->data;
		/* need to extract the HM/CCS sequence number here */
		if ( rr->type == SSL3_RT_HANDSHAKE ||
			rr->type == SSL3_RT_CHANGE_CIPHER_SPEC)
			{
			unsigned short seq_num;
			struct hm_header_st msg_hdr;
			struct ccs_header_st ccs_hdr;

			if ( rr->type == SSL3_RT_HANDSHAKE)
				{
				dtls1_get_message_header(data, &msg_hdr);
				seq_num = msg_hdr.seq;
				*offset = msg_hdr.frag_off;
				}
			else
				{
				dtls1_get_ccs_header(data, &ccs_hdr);
				seq_num = ccs_hdr.seq;
				*offset = 0;
				}
				
			/* this is either a record we're waiting for, or a
			 * retransmit of something we happened to previously 
			 * receive (higher layers will drop the repeat silently */
			if ( seq_num < s->d1->handshake_read_seq)
				return 0;
			if (rr->type == SSL3_RT_HANDSHAKE && 
				seq_num == s->d1->handshake_read_seq &&
				msg_hdr.frag_off < s->d1->r_msg_hdr.frag_off)
				return 0;
			else if ( seq_num == s->d1->handshake_read_seq &&
				(rr->type == SSL3_RT_CHANGE_CIPHER_SPEC ||
					msg_hdr.frag_off == s->d1->r_msg_hdr.frag_off))
				return 0;
			else
				{
				*priority = seq_num;
				return 1;
				}
			}
		else /* unknown record type */
			return 0;
		}

	return 0;
	}
#endif

void
dtls1_reset_seq_numbers(SSL *s, int rw)
	{
	unsigned char *seq;
	unsigned int seq_bytes = sizeof(s->s3->read_sequence);

	if ( rw & SSL3_CC_READ)
		{
		seq = s->s3->read_sequence;
		s->d1->r_epoch++;

		pq_64bit_assign(&(s->d1->bitmap.map), &(s->d1->next_bitmap.map));
		s->d1->bitmap.length = s->d1->next_bitmap.length;
		pq_64bit_assign(&(s->d1->bitmap.max_seq_num), 
			&(s->d1->next_bitmap.max_seq_num));

		pq_64bit_free(&(s->d1->next_bitmap.map));
		pq_64bit_free(&(s->d1->next_bitmap.max_seq_num));
		memset(&(s->d1->next_bitmap), 0x00, sizeof(DTLS1_BITMAP));
		pq_64bit_init(&(s->d1->next_bitmap.map));
		pq_64bit_init(&(s->d1->next_bitmap.max_seq_num));
		}
	else
		{
		seq = s->s3->write_sequence;
		s->d1->w_epoch++;
		}

	memset(seq, 0x00, seq_bytes);
	}

#if PQ_64BIT_IS_INTEGER
static PQ_64BIT
bytes_to_long_long(unsigned char *bytes, PQ_64BIT *num)
       {
       PQ_64BIT _num;

       _num = (((PQ_64BIT)bytes[0]) << 56) |
               (((PQ_64BIT)bytes[1]) << 48) |
               (((PQ_64BIT)bytes[2]) << 40) |
               (((PQ_64BIT)bytes[3]) << 32) |
               (((PQ_64BIT)bytes[4]) << 24) |
               (((PQ_64BIT)bytes[5]) << 16) |
               (((PQ_64BIT)bytes[6]) <<  8) |
               (((PQ_64BIT)bytes[7])      );

	   *num = _num ;
       return _num;
       }
#endif


static void
dtls1_clear_timeouts(SSL *s)
	{
	memset(&(s->d1->timeout), 0x00, sizeof(struct dtls1_timeout_st));
	}