/* *  net/dccp/input.c * *  An implementation of the DCCP protocol *  Arnaldo Carvalho de Melo <acme@conectiva.com.br> * *	This program is free software; you can redistribute it and/or *	modify it under the terms of the GNU General Public License *	as published by the Free Software Foundation; either version *	2 of the License, or (at your option) any later version. */ #include <linux/dccp.h>#include <linux/skbuff.h> #include <net/sock.h> #include "ackvec.h"#include "ccid.h"#include "dccp.h" static void dccp_fin(struct sock *sk, struct sk_buff *skb){	sk->sk_shutdown |= RCV_SHUTDOWN;	sock_set_flag(sk, SOCK_DONE);	__skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);	__skb_queue_tail(&sk->sk_receive_queue, skb);	skb_set_owner_r(skb, sk);	sk->sk_data_ready(sk, 0);} static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb){	dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);	dccp_fin(sk, skb);	dccp_set_state(sk, DCCP_CLOSED);	sk_wake_async(sk, 1, POLL_HUP);} static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb){	/*	 *   Step 7: Check for unexpected packet types	 *      If (S.is_server and P.type == CloseReq)	 *	  Send Sync packet acknowledging P.seqno	 *	  Drop packet and return	 */	if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);		return;	} 	if (sk->sk_state != DCCP_CLOSING)		dccp_set_state(sk, DCCP_CLOSING);	dccp_send_close(sk, 0);} static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb){	struct dccp_sock *dp = dccp_sk(sk); 	if (dccp_msk(sk)->dccpms_send_ack_vector)		dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,					    DCCP_SKB_CB(skb)->dccpd_ack_seq);} static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb){	const struct dccp_hdr *dh = dccp_hdr(skb);	struct dccp_sock *dp = dccp_sk(sk);	u64 lswl, lawl; 	/*	 *   Step 5: Prepare sequence numbers for Sync	 *     If P.type == Sync or P.type == SyncAck,	 *	  If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,	 *	     / * P is valid, so update sequence number variables	 *		 accordingly.  After this update, P will pass the tests	 *		 in Step 6.  A SyncAck is generated if necessary in	 *		 Step 15 * /	 *	     Update S.GSR, S.SWL, S.SWH	 *	  Otherwise,	 *	     Drop packet and return	 */	if (dh->dccph_type == DCCP_PKT_SYNC ||	    dh->dccph_type == DCCP_PKT_SYNCACK) {		if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,			      dp->dccps_awl, dp->dccps_awh) &&		    !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))			dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);		else			return -1;	} 	/*	 *   Step 6: Check sequence numbers	 *      Let LSWL = S.SWL and LAWL = S.AWL	 *      If P.type == CloseReq or P.type == Close or P.type == Reset,	 *	  LSWL := S.GSR + 1, LAWL := S.GAR	 *      If LSWL <= P.seqno <= S.SWH	 *	     and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),	 *	  Update S.GSR, S.SWL, S.SWH	 *	  If P.type != Sync,	 *	     Update S.GAR	 *      Otherwise,	 *	  Send Sync packet acknowledging P.seqno	 *	  Drop packet and return	 */	lswl = dp->dccps_swl;	lawl = dp->dccps_awl; 	if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||	    dh->dccph_type == DCCP_PKT_CLOSE ||	    dh->dccph_type == DCCP_PKT_RESET) {		lswl = dp->dccps_gsr;		dccp_inc_seqno(&lswl);		lawl = dp->dccps_gar;	} 	if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&	    (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||	     between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,		       lawl, dp->dccps_awh))) {		dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); 		if (dh->dccph_type != DCCP_PKT_SYNC &&		    (DCCP_SKB_CB(skb)->dccpd_ack_seq !=		     DCCP_PKT_WITHOUT_ACK_SEQ))			dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;	} else {		DCCP_WARN("DCCP: Step 6 failed for %s packet, "			  "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "			  "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "			  "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),			  (unsigned long long) lswl,			  (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq,			  (unsigned long long) dp->dccps_swh,			  (DCCP_SKB_CB(skb)->dccpd_ack_seq ==				DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",			  (unsigned long long) lawl,			  (unsigned long long) DCCP_SKB_CB(skb)->dccpd_ack_seq,			  (unsigned long long) dp->dccps_awh);		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);		return -1;	} 	return 0;} static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,				  const struct dccp_hdr *dh, const unsigned len){	struct dccp_sock *dp = dccp_sk(sk); 	switch (dccp_hdr(skb)->dccph_type) {	case DCCP_PKT_DATAACK:	case DCCP_PKT_DATA:		/*		 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED		 * option if it is.		 */		__skb_pull(skb, dh->dccph_doff * 4);		__skb_queue_tail(&sk->sk_receive_queue, skb);		skb_set_owner_r(skb, sk);		sk->sk_data_ready(sk, 0);		return 0;	case DCCP_PKT_ACK:		goto discard;	case DCCP_PKT_RESET:		/*		 *  Step 9: Process Reset		 *	If P.type == Reset,		 *		Tear down connection		 *		S.state := TIMEWAIT		 *		Set TIMEWAIT timer		 *		Drop packet and return		*/		dccp_fin(sk, skb);		dccp_time_wait(sk, DCCP_TIME_WAIT, 0);		return 0;	case DCCP_PKT_CLOSEREQ:		dccp_rcv_closereq(sk, skb);		goto discard;	case DCCP_PKT_CLOSE:		dccp_rcv_close(sk, skb);		return 0;	case DCCP_PKT_REQUEST:		/* Step 7		 *   or (S.is_server and P.type == Response)		 *   or (S.is_client and P.type == Request)		 *   or (S.state >= OPEN and P.type == Request		 *	and P.seqno >= S.OSR)		 *    or (S.state >= OPEN and P.type == Response		 *	and P.seqno >= S.OSR)		 *    or (S.state == RESPOND and P.type == Data),		 *  Send Sync packet acknowledging P.seqno		 *  Drop packet and return		 */		if (dp->dccps_role != DCCP_ROLE_LISTEN)			goto send_sync;		goto check_seq;	case DCCP_PKT_RESPONSE:		if (dp->dccps_role != DCCP_ROLE_CLIENT)			goto send_sync;check_seq:		if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {send_sync:			dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,				       DCCP_PKT_SYNC);		}		break;	case DCCP_PKT_SYNC:		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,			       DCCP_PKT_SYNCACK);		/*		 * From RFC 4340, sec. 5.7		 *		 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets		 * MAY have non-zero-length application data areas, whose		 * contents receivers MUST ignore.		 */		goto discard;	} 	DCCP_INC_STATS_BH(DCCP_MIB_INERRS);discard:	__kfree_skb(skb);	return 0;} int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,			 const struct dccp_hdr *dh, const unsigned len){	struct dccp_sock *dp = dccp_sk(sk); 	if (dccp_check_seqno(sk, skb))		goto discard; 	if (dccp_parse_options(sk, skb))		goto discard; 	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)		dccp_event_ack_recv(sk, skb); 	if (dccp_msk(sk)->dccpms_send_ack_vector &&	    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,			    DCCP_SKB_CB(skb)->dccpd_seq,			    DCCP_ACKVEC_STATE_RECEIVED))		goto discard; 	ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);	ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 	return __dccp_rcv_established(sk, skb, dh, len);discard:	__kfree_skb(skb);	return 0;} EXPORT_SYMBOL_GPL(dccp_rcv_established); static int dccp_rcv_request_sent_state_process(struct sock *sk,					       struct sk_buff *skb,					       const struct dccp_hdr *dh,					       const unsigned len){	/*	 *  Step 4: Prepare sequence numbers in REQUEST	 *     If S.state == REQUEST,	 *	  If (P.type == Response or P.type == Reset)	 *		and S.AWL <= P.ackno <= S.AWH,	 *	     / * Set sequence number variables corresponding to the	 *		other endpoint, so P will pass the tests in Step 6 * /	 *	     Set S.GSR, S.ISR, S.SWL, S.SWH	 *	     / * Response processing continues in Step 10; Reset	 *		processing continues in Step 9 * /	*/	if (dh->dccph_type == DCCP_PKT_RESPONSE) {		const struct inet_connection_sock *icsk = inet_csk(sk);		struct dccp_sock *dp = dccp_sk(sk); 		/* Stop the REQUEST timer */		inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);		BUG_TRAP(sk->sk_send_head != NULL);		__kfree_skb(sk->sk_send_head);		sk->sk_send_head = NULL; 		if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,			       dp->dccps_awl, dp->dccps_awh)) {			dccp_pr_debug("invalid ackno: S.AWL=%llu, "				      "P.ackno=%llu, S.AWH=%llu \n",				      (unsigned long long)dp->dccps_awl,			   (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,				      (unsigned long long)dp->dccps_awh);			goto out_invalid_packet;		} 		if (dccp_parse_options(sk, skb))			goto out_invalid_packet; 		if (dccp_msk(sk)->dccpms_send_ack_vector &&		    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,				    DCCP_SKB_CB(skb)->dccpd_seq,				    DCCP_ACKVEC_STATE_RECEIVED))			goto out_invalid_packet; /* FIXME: change error code */ 		dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;		dccp_update_gsr(sk, dp->dccps_isr);		/*		 * SWL and AWL are initially adjusted so that they are not less than		 * the initial Sequence Numbers received and sent, respectively:		 *	SWL := max(GSR + 1 - floor(W/4), ISR),		 *	AWL := max(GSS - W' + 1, ISS).		 * These adjustments MUST be applied only at the beginning of the		 * connection.		 *		 * AWL was adjusted in dccp_v4_connect -acme		 */		dccp_set_seqno(&dp->dccps_swl,			       max48(dp->dccps_swl, dp->dccps_isr)); 		dccp_sync_mss(sk, icsk->icsk_pmtu_cookie); 		/*		 *    Step 10: Process REQUEST state (second part)		 *       If S.state == REQUEST,		 *	  / * If we get here, P is a valid Response from the		 *	      server (see Step 4), and we should move to		 *	      PARTOPEN state. PARTOPEN means send an Ack,		 *	      don't send Data packets, retransmit Acks		 *	      periodically, and always include any Init Cookie		 *	      from the Response * /		 *	  S.state := PARTOPEN		 *	  Set PARTOPEN timer		 *	  Continue with S.state == PARTOPEN		 *	  / * Step 12 will send the Ack completing the		 *	      three-way handshake * /		 */		dccp_set_state(sk, DCCP_PARTOPEN); 		/* Make sure socket is routed, for correct metrics. */		icsk->icsk_af_ops->rebuild_header(sk); 		if (!sock_flag(sk, SOCK_DEAD)) {			sk->sk_state_change(sk);			sk_wake_async(sk, 0, POLL_OUT);		} 		if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||		    icsk->icsk_accept_queue.rskq_defer_accept) {			/* Save one ACK. Data will be ready after			 * several ticks, if write_pending is set.			 *			 * It may be deleted, but with this feature tcpdumps			 * look so _wonderfully_ clever, that I was not able			 * to stand against the temptation 8)     --ANK			 */			/*			 * OK, in DCCP we can as well do a similar trick, its			 * even in the draft, but there is no need for us to			 * schedule an ack here, as dccp_sendmsg does this for			 * us, also stated in the draft. -acme			 */			__kfree_skb(skb);			return 0;		}		dccp_send_ack(sk);		return -1;	} out_invalid_packet:	/* dccp_v4_do_rcv will send a reset */	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;	return 1;} static int dccp_rcv_respond_partopen_state_process(struct sock *sk,						   struct sk_buff *skb,						   const struct dccp_hdr *dh,						   const unsigned len){	int queued = 0; 	switch (dh->dccph_type) {	case DCCP_PKT_RESET:		inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);		break;	case DCCP_PKT_DATA:		if (sk->sk_state == DCCP_RESPOND)			break;	case DCCP_PKT_DATAACK:	case DCCP_PKT_ACK:		/*		 * FIXME: we should be reseting the PARTOPEN (DELACK) timer		 * here but only if we haven't used the DELACK timer for		 * something else, like sending a delayed ack for a TIMESTAMP		 * echo, etc, for now were not clearing it, sending an extra		 * ACK when there is nothing else to do in DELACK is not a big		 * deal after all.		 */ 		/* Stop the PARTOPEN timer */		if (sk->sk_state == DCCP_PARTOPEN)			inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 		dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;		dccp_set_state(sk, DCCP_OPEN); 		if (dh->dccph_type == DCCP_PKT_DATAACK ||		    dh->dccph_type == DCCP_PKT_DATA) {			__dccp_rcv_established(sk, skb, dh, len);			queued = 1; /* packet was queued				       (by __dccp_rcv_established) */		}		break;	} 	return queued;} int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,			   struct dccp_hdr *dh, unsigned len){	struct dccp_sock *dp = dccp_sk(sk);	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);	const int old_state = sk->sk_state;	int queued = 0; 	/*	 *  Step 3: Process LISTEN state	 *	 *     If S.state == LISTEN,	 *	 If P.type == Request or P contains a valid Init Cookie option,	 *	      (* Must scan the packet's options to check for Init	 *		 Cookies.  Only Init Cookies are processed here,	 *		 however; other options are processed in Step 8.  This	 *		 scan need only be performed if the endpoint uses Init	 *		 Cookies *)	 *	      (* Generate a new socket and switch to that socket *)	 *	      Set S := new socket for this port pair	 *	      S.state = RESPOND	 *	      Choose S.ISS (initial seqno) or set from Init Cookies	 *	      Initialize S.GAR := S.ISS	 *	      Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init	 *	      Cookies Continue with S.state == RESPOND	 *	      (* A Response packet will be generated in Step 11 *)	 *	 Otherwise,	 *	      Generate Reset(No Connection) unless P.type == Reset	 *	      Drop packet and return	 */	if (sk->sk_state == DCCP_LISTEN) {		if (dh->dccph_type == DCCP_PKT_REQUEST) {			if (inet_csk(sk)->icsk_af_ops->conn_request(sk,								    skb) < 0)				return 1; 			/* FIXME: do congestion control initialization */			goto discard;		}		if (dh->dccph_type == DCCP_PKT_RESET)			goto discard; 		/* Caller (dccp_v4_do_rcv) will send Reset */		dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;		return 1;	} 	if (sk->sk_state != DCCP_REQUESTING) {		if (dccp_check_seqno(sk, skb))			goto discard; 		/*		 * Step 8: Process options and mark acknowledgeable		 */		if (dccp_parse_options(sk, skb))			goto discard; 		if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)			dccp_event_ack_recv(sk, skb); 		if (dccp_msk(sk)->dccpms_send_ack_vector &&		    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,				    DCCP_SKB_CB(skb)->dccpd_seq,				    DCCP_ACKVEC_STATE_RECEIVED))			goto discard; 		ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);		ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);	} 	/*	 *  Step 9: Process Reset	 *	If P.type == Reset,	 *		Tear down connection	 *		S.state := TIMEWAIT	 *		Set TIMEWAIT timer	 *		Drop packet and return	*/	if (dh->dccph_type == DCCP_PKT_RESET) {		/*

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