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Commit c49b2272 authored by Gerrit Renker's avatar Gerrit Renker
Browse files

dccp: Integration of dynamic feature activation - part 3 (client side) 



This integrates feature-activation in the client, with these details:

 1. When dccp_parse_options() fails, the reset code is already set, request_sent
    _state_process() currently overrides this with `Packet Error', which is not
    intended - so changed to use the reset code set in dccp_parse_options();

 2. There was a FIXME to change the error code when dccp_ackvec_add() fails.
    I have looked this up and found that: 
    * the check whether ackno < ISN is already made earlier,
    * this Response is likely the 1st packet with an Ackno that the client gets,
    * so when dccp_ackvec_add() fails, the reason is likely not a packet error.

 3. When feature negotiation fails, the socket should be marked as not usable,
    so that the application is notified that an error occurs. This is achieved
    by a new label, which uses an error code of `Aborted' and which sets the
    socket state to CLOSED, as well as sk_err.

 4. Avoids parsing the Ack twice in Respond state by not doing option processing
    again in dccp_rcv_respond_partopen_state_process (as option processing has
    already been done on the request_sock in dccp_check_req).    

Since this addresses congestion-control initialisation, a corresponding
FIXME has been removed.

Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
parent e70cacb9

net/dccp/input.c

+26 −4
Original line number Diff line number Diff line
@@ -421,8 +421,13 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk, 
			goto out_invalid_packet;

		}



		/*

		 * If option processing (Step 8) failed, return 1 here so that

		 * dccp_v4_do_rcv() sends a Reset. The Reset code depends on

		 * the option type and is set in dccp_parse_options().

		 */

		if (dccp_parse_options(sk, NULL, skb))

			goto out_invalid_packet;

			return 1;



		/* Obtain usec RTT sample from SYN exchange (used by CCID 3) */

		if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
@@ -475,6 +480,15 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk, 
		 */

		dccp_set_state(sk, DCCP_PARTOPEN);



		/*

		 * If feature negotiation was successful, activate features now;

		 * an activation failure means that this host could not activate

		 * one ore more features (e.g. insufficient memory), which would

		 * leave at least one feature in an undefined state.

		 */

		if (dccp_feat_activate_values(sk, &dp->dccps_featneg))

			goto unable_to_proceed;



		/* Make sure socket is routed, for correct metrics. */

		icsk->icsk_af_ops->rebuild_header(sk);
@@ -509,6 +523,16 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk, 
	/* dccp_v4_do_rcv will send a reset */

	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;

	return 1;



unable_to_proceed:

	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED;

	/*

	 * We mark this socket as no longer usable, so that the loop in

	 * dccp_sendmsg() terminates and the application gets notified.

	 */

	dccp_set_state(sk, DCCP_CLOSED);

	sk->sk_err = ECOMM;

	return 1;

}



static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
@@ -600,7 +624,7 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 
		return 1;

	}



	if (sk->sk_state != DCCP_REQUESTING) {

	if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) {

		if (dccp_check_seqno(sk, skb))

			goto discard;
@@ -665,8 +689,6 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 
		return 1;



	case DCCP_REQUESTING:

		/* FIXME: do congestion control initialization */



		queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);

		if (queued >= 0)

			return queued;