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