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dccp: Preference list reconciliation 

This provides two functions to
 * reconcile preference lists (with appropriate return codes) and
 * reorder the preference list if successful reconciliation changed the
   preferred value.

The patch also removes the old code for processing SP/NN Change options, since
new code to process these is mostly there already; related references have been
commented out.

The code for processing Change options follows in the next patch.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
This commit is contained in:
Gerrit Renker 2008-09-04 07:30:19 +02:00
parent f8a644c07e
commit c664d4f4e2
1 changed files with 75 additions and 2 deletions
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77
net/dccp/feat.c
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@ -718,6 +718,76 @@ static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
return 0;
}
/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
{
u8 c, s;
for (s = 0; s < slen; s++)
for (c = 0; c < clen; c++)
if (servlist[s] == clilist[c])
return servlist[s];
return -1;
}
/**
* dccp_feat_prefer - Move preferred entry to the start of array
* Reorder the @array_len elements in @array so that @preferred_value comes
* first. Returns >0 to indicate that @preferred_value does occur in @array.
*/
static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
{
u8 i, does_occur = 0;
if (array != NULL) {
for (i = 0; i < array_len; i++)
if (array[i] == preferred_value) {
array[i] = array[0];
does_occur++;
}
if (does_occur)
array[0] = preferred_value;
}
return does_occur;
}
/**
* dccp_feat_reconcile - Reconcile SP preference lists
* @fval: SP list to reconcile into
* @arr: received SP preference list
* @len: length of @arr in bytes
* @is_server: whether this side is the server (and @fv is the server's list)
* @reorder: whether to reorder the list in @fv after reconciling with @arr
* When successful, > 0 is returned and the reconciled list is in @fval.
* A value of 0 means that negotiation failed (no shared entry).
*/
static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
bool is_server, bool reorder)
{
int rc;
if (!fv->sp.vec || !arr) {
DCCP_CRIT("NULL feature value or array");
return 0;
}
if (is_server)
rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
else
rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
if (!reorder)
return rc;
if (rc < 0)
return 0;
/*
* Reorder list: used for activating features and in dccp_insert_fn_opt.
*/
return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
}
#ifdef __this_is_the_old_framework_and_will_be_removed_later_in_a_subsequent_patch
static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
u8 *rpref, u8 rlen)
{
@ -913,6 +983,7 @@ static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
return 0;
}
#endif /* (later) */
static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
u8 type, u8 feature)
@ -988,12 +1059,14 @@ int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
switch (feature) {
/* deal with SP features */
case DCCPF_CCID:
rc = dccp_feat_sp(sk, type, feature, val, len);
/* XXX Obsoleted by next patch
rc = dccp_feat_sp(sk, type, feature, val, len); */
break;
/* deal with NN features */
case DCCPF_ACK_RATIO:
rc = dccp_feat_nn(sk, type, feature, val, len);
/* XXX Obsoleted by next patch
rc = dccp_feat_nn(sk, type, feature, val, len); */
break;
/* XXX implement other features */