[DCCP]: Initial feature negotiation implementation

Still needs more work, but boots and doesn't crashes, even
does some negotiation!

18:38:52.174934  127.0.0.1.43458 > 127.0.0.1.5001: request <change_l ack_ratio 2, change_r ccid 2, change_l ccid 2>
18:38:52.218526  127.0.0.1.5001 > 127.0.0.1.43458: response <nop, nop, change_l ack_ratio 2, confirm_r ccid 2 2, confirm_l ccid 2 2, confirm_r ack_ratio 2>
18:38:52.185398  127.0.0.1.43458 > 127.0.0.1.5001: <nop, confirm_r ack_ratio 2, ack_vector0 0x00, elapsed_time 212>

:-)

Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 137 insertions, 2 deletions

diff --git a/net/dccp/options.c b/net/dccp/options.c
index 0a76426c9aea..7f99306c8e99 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -21,12 +21,14 @@
 #include "ackvec.h"
 #include "ccid.h"
 #include "dccp.h"
+#include "feat.h"
 
 /* stores the default values for new connection. may be changed with sysctl */
 static const struct dccp_options dccpo_default_values = {
         .dccpo_sequence_window    = DCCPF_INITIAL_SEQUENCE_WINDOW,
         .dccpo_rx_ccid            = DCCPF_INITIAL_CCID,
         .dccpo_tx_ccid            = DCCPF_INITIAL_CCID,
+        .dccpo_ack_ratio          = DCCPF_INITIAL_ACK_RATIO,
         .dccpo_send_ack_vector    = DCCPF_INITIAL_SEND_ACK_VECTOR,
         .dccpo_send_ndp_count     = DCCPF_INITIAL_SEND_NDP_COUNT,
 };
@@ -69,6 +71,8 @@ int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
         unsigned char opt, len;
         unsigned char *value;
         u32 elapsed_time;
+        int rc;
+        int mandatory = 0;
 
         memset(opt_recv, 0, sizeof(*opt_recv));
 
@@ -100,6 +104,11 @@ int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
                 switch (opt) {
                 case DCCPO_PADDING:
                         break;
+                case DCCPO_MANDATORY:
+                        if (mandatory)
+                                goto out_invalid_option;
+                        mandatory = 1;
+                        break;
                 case DCCPO_NDP_COUNT:
                         if (len > 3)
                                 goto out_invalid_option;
@@ -108,6 +117,31 @@ int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
                         dccp_pr_debug("%sNDP count=%d\n", debug_prefix,
                                       opt_recv->dccpor_ndp);
                         break;
+                case DCCPO_CHANGE_L:
+                        /* fall through */
+                case DCCPO_CHANGE_R:
+                        if (len < 2)
+                                goto out_invalid_option;
+                        rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
+                                                   len - 1);
+                        /*
+                         * When there is a change error, change_recv is
+                         * responsible for dealing with it.  i.e. reply with an
+                         * empty confirm.
+                         * If the change was mandatory, then we need to die.
+                         */
+                        if (rc && mandatory)
+                                goto out_invalid_option;
+                        break;
+                case DCCPO_CONFIRM_L:
+                        /* fall through */
+                case DCCPO_CONFIRM_R:
+                        if (len < 2)
+                                goto out_invalid_option;
+                        if (dccp_feat_confirm_recv(sk, opt, *value,
+                                                   value + 1, len - 1))
+                                goto out_invalid_option;
+                        break;
                 case DCCPO_ACK_VECTOR_0:
                 case DCCPO_ACK_VECTOR_1:
                         if (pkt_type == DCCP_PKT_DATA)
@@ -208,6 +242,9 @@ int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
                                 sk, opt, len);
                         break;
                 }
+
+                if (opt != DCCPO_MANDATORY)
+                        mandatory = 0;
         }
 
         return 0;
@@ -356,7 +393,7 @@ void dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 {
         struct timeval tv;
         u32 now;
-        
+
         dccp_timestamp(sk, &tv);
         now = timeval_usecs(&tv) / 10;
         /* yes this will overflow but that is the point as we want a
@@ -402,7 +439,7 @@ static void dccp_insert_option_timestamp_echo(struct sock *sk,
         tstamp_echo = htonl(dp->dccps_timestamp_echo);
         memcpy(to, &tstamp_echo, 4);
         to += 4;
-        
+
         if (elapsed_time_len == 2) {
                 const u16 var16 = htons((u16)elapsed_time);
                 memcpy(to, &var16, 2);
@@ -421,6 +458,93 @@ static void dccp_insert_option_timestamp_echo(struct sock *sk,
         dp->dccps_timestamp_time.tv_usec = 0;
 }
 
+static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
+                                u8 *val, u8 len)
+{
+        u8 *to;
+
+        if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
+                LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small"
+                               " to insert feature %d option!\n", feat);
+                return -1;
+        }
+
+        DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
+
+        to    = skb_push(skb, len + 3);
+        *to++ = type;
+        *to++ = len + 3;
+        *to++ = feat;
+
+        if (len)
+                memcpy(to, val, len);
+        dccp_pr_debug("option %d feat %d len %d\n", type, feat, len);
+
+        return 0;
+}
+
+static void dccp_insert_feat(struct sock *sk, struct sk_buff *skb)
+{
+        struct dccp_sock *dp = dccp_sk(sk);
+        struct dccp_opt_pend *opt, *next;
+        int change = 0;
+
+        /* confirm any options [NN opts] */
+        list_for_each_entry_safe(opt, next, &dp->dccps_options.dccpo_conf,
+                                 dccpop_node) {
+                dccp_insert_feat_opt(skb, opt->dccpop_type,
+                                     opt->dccpop_feat, opt->dccpop_val,
+                                     opt->dccpop_len);
+                /* fear empty confirms */
+                if (opt->dccpop_val)
+                        kfree(opt->dccpop_val);
+                kfree(opt);
+        }
+        INIT_LIST_HEAD(&dp->dccps_options.dccpo_conf);
+
+        /* see which features we need to send */
+        list_for_each_entry(opt, &dp->dccps_options.dccpo_pending,
+                            dccpop_node) {
+                /* see if we need to send any confirm */
+                if (opt->dccpop_sc) {
+                        dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
+                                             opt->dccpop_feat,
+                                             opt->dccpop_sc->dccpoc_val,
+                                             opt->dccpop_sc->dccpoc_len);
+
+                        BUG_ON(!opt->dccpop_sc->dccpoc_val);
+                        kfree(opt->dccpop_sc->dccpoc_val);
+                        kfree(opt->dccpop_sc);
+                        opt->dccpop_sc = NULL;
+                }
+
+                /* any option not confirmed, re-send it */
+                if (!opt->dccpop_conf) {
+                        dccp_insert_feat_opt(skb, opt->dccpop_type,
+                                             opt->dccpop_feat, opt->dccpop_val,
+                                             opt->dccpop_len);
+                        change++;
+                }
+        }
+
+        /* Retransmit timer.
+         * If this is the master listening sock, we don't set a timer on it.  It
+         * should be fine because if the dude doesn't receive our RESPONSE
+         * [which will contain the CHANGE] he will send another REQUEST which
+         * will "retrnasmit" the change.
+         */
+        if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
+                dccp_pr_debug("reset feat negotiation timer %p\n", sk);
+
+                /* XXX don't reset the timer on re-transmissions.  I.e. reset it
+                 * only when sending new stuff i guess.  Currently the timer
+                 * never backs off because on re-transmission it just resets it!
+                 */
+                inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+                                          inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
+        }
+}
+
 void dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 {
         struct dccp_sock *dp = dccp_sk(sk);
@@ -447,6 +571,17 @@ void dccp_insert_options(struct sock *sk, struct sk_buff *skb)
                 dp->dccps_hc_tx_insert_options = 0;
         }
 
+        /* Feature negotiation */
+        switch(DCCP_SKB_CB(skb)->dccpd_type) {
+                /* Data packets can't do feat negotiation */
+        case DCCP_PKT_DATA:
+        case DCCP_PKT_DATAACK:
+                break;
+        default:
+                dccp_insert_feat(sk, skb);
+                break;
+        }
+
         /* XXX: insert other options when appropriate */
 
         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {