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: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>

1 files changed, 26 insertions, 4 deletions

diff --git a/net/dccp/input.c b/net/dccp/input.c
index 3070015edc75..0672b7e1763e 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -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 @@ 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;
+
+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;