1 /* SPDX-License-Identifier: GPL-2.0-only */
9  *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
20  * 	DCCP - specific warning and debugging macros.
56  *  Set safe upper bounds for header and option length. Since Data Offset is 8
59  *    - DCCP-Response with ACK Subheader and 4 bytes of Service code      OR
60  *    - DCCP-Reset    with ACK Subheader and 4 bytes of Reset Code fields
61  *  Hence a safe upper bound for the maximum option length is 1020-28 = 992
65 #define DCCP_MAX_OPT_LEN (MAX_DCCP_SPECIFIC_HEADER - DCCP_MAX_PACKET_HDR)
68 /* Upper bound for initial feature-negotiation overhead (padded to 32 bits) */
71 #define DCCP_TIMEWAIT_LEN (60 * HZ) /* how long to wait to destroy TIME-WAIT
78  * The maximum back-off value for retransmissions. This is needed for
79  *  - retransmitting client-Requests (sec. 8.1.1),
80  *  - retransmitting Close/CloseReq when closing (sec. 8.3),
81  *  - feature-negotiation retransmission (sec. 6.6.3),
82  *  - Acks in client-PARTOPEN state (sec. 8.1.5).
93 /* sysctl variables for DCCP */
101  *	48-bit sequence number arithmetic (signed and unsigned)
104 #define UINT48_MAX	  0xFFFFFFFFFFFFLL		/* 2^48 - 1 */
105 #define COMPLEMENT48(x)	 (0x1000000000000LL - (x))	/* 2^48 - x */
106 #define TO_SIGNED48(x)	 (((x) < INT48_MIN)? (x) : -COMPLEMENT48( (x)))
107 #define TO_UNSIGNED48(x) (((x) >= 0)?	     (x) :  COMPLEMENT48(-(x)))
116 /* signed mod-2^48 distance: pos. if seqno1 < seqno2, neg. if seqno1 > seqno2 */
127 	return (s64)((seq2 << 16) - (seq1 << 16)) > 0;  in before48()
136 	return (seq3 << 16) - (seq2 << 16) >= (seq1 << 16) - (seq2 << 16);  in between48()
145  * dccp_loss_count - Approximate the number of lost data packets in a burst loss
155 	delta -= ndp + 1;  in dccp_loss_count()
161  * dccp_loss_free - Evaluate condition for data loss from RFC 4340, 7.7.1
204 	if (dh->dccph_cscov == 0)  in dccp_csum_coverage()
205 		return skb->len;  in dccp_csum_coverage()
206 	return (dh->dccph_doff + dh->dccph_cscov - 1) * sizeof(u32);  in dccp_csum_coverage()
213 	if (cov >= skb->len)  in dccp_csum_outgoing()
214 		dccp_hdr(skb)->dccph_cscov = 0;  in dccp_csum_outgoing()
216 	skb->csum = skb_checksum(skb, 0, (cov > skb->len)? skb->len : cov, 0);  in dccp_csum_outgoing()
306 		       poll_table *wait);
321 	if (dp->dccps_service == service)  in dccp_bad_service_code()
323 	return !dccp_list_has_service(dp->dccps_service_list, service);  in dccp_bad_service_code()
327  * dccp_skb_cb  -  DCCP per-packet control information
336  * This is used for transmission as well as for reception.
354 #define DCCP_SKB_CB(__skb) ((struct dccp_skb_cb *)&((__skb)->cb[0]))
359 	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;  in dccp_non_data_packet()
372 	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;  in dccp_data_packet()
382 	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;  in dccp_packet_without_ack()
393 	dh->dccph_seq2 = 0;  in dccp_hdr_set_seq()
394 	dh->dccph_seq = htons((gss >> 32) & 0xfffff);  in dccp_hdr_set_seq()
395 	dhx->dccph_seq_low = htonl(gss & 0xffffffff);  in dccp_hdr_set_seq()
401 	dhack->dccph_reserved1 = 0;  in dccp_hdr_set_ack()
402 	dhack->dccph_ack_nr_high = htons(gsr >> 32);  in dccp_hdr_set_ack()
403 	dhack->dccph_ack_nr_low  = htonl(gsr & 0xffffffff);  in dccp_hdr_set_ack()
410 	if (after48(seq, dp->dccps_gsr))  in dccp_update_gsr()
411 		dp->dccps_gsr = seq;  in dccp_update_gsr()
413 	dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);  in dccp_update_gsr()
417 	 * always > 32, so for the first W/W' packets in the lifetime of a  in dccp_update_gsr()
418 	 * connection we always have to adjust SWL.  in dccp_update_gsr()
420 	 * the feature-remote value of Sequence Window: nothing stops the peer  in dccp_update_gsr()
421 	 * from updating this value while we are busy adjusting SWL for the  in dccp_update_gsr()
423 	 * Therefore it is safer to always make sure that the Sequence Window  in dccp_update_gsr()
425 	 * continually updating the feature-remote Sequence-Window.  in dccp_update_gsr()
427 	 * (48 bit), and this measure prevents Sequence-number attacks.  in dccp_update_gsr()
429 	if (before48(dp->dccps_swl, dp->dccps_isr))  in dccp_update_gsr()
430 		dp->dccps_swl = dp->dccps_isr;  in dccp_update_gsr()
431 	dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);  in dccp_update_gsr()
438 	dp->dccps_gss = seq;  in dccp_update_gss()
439 	/* Ack validity window depends on local Sequence Window value (7.5.1) */  in dccp_update_gss()
440 	dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);  in dccp_update_gss()
441 	/* Adjust AWL so that it is not below ISS - see comment above for SWL */  in dccp_update_gss()
442 	if (before48(dp->dccps_awl, dp->dccps_iss))  in dccp_update_gss()
443 		dp->dccps_awl = dp->dccps_iss;  in dccp_update_gss()
444 	dp->dccps_awh = dp->dccps_gss;  in dccp_update_gss()
449 	return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&  in dccp_ackvec_pending()
450 	       !dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);  in dccp_ackvec_pending()