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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2008-09-04 07:30:19 +0200
committerGerrit Renker <gerrit@erg.abdn.ac.uk>2008-09-04 07:45:32 +0200
commit4861a354430d2ea36847ef88086c7449b4f385b6 (patch)
tree53a40f7f81c6f683b5c998f7a295de4bef2b5abf /net/dccp
parent624a965a93610152b10c73d050ed44812efa8abe (diff)
dccp: Support for exchanging of NN options in established state
This patch provides support for the reception of NN options in (PART)OPEN state. It is a combination of change_recv() and confirm_recv(), specifically geared towards receiving the `fast-path' NN options. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Diffstat (limited to 'net/dccp')
-rw-r--r--net/dccp/feat.c96
1 files changed, 96 insertions, 0 deletions
diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index 5be8b85ac74..c847c80d1b9 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -1247,6 +1247,93 @@ confirmation_failed:
}
/**
+ * dccp_feat_handle_nn_established - Fast-path reception of NN options
+ * @sk: socket of an established DCCP connection
+ * @mandatory: whether @opt was preceded by a Mandatory option
+ * @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only)
+ * @feat: NN number, one of %dccp_feature_numbers
+ * @val: NN value
+ * @len: length of @val in bytes
+ * This function combines the functionality of change_recv/confirm_recv, with
+ * the following differences (reset codes are the same):
+ * - cleanup after receiving the Confirm;
+ * - values are directly activated after successful parsing;
+ * - deliberately restricted to NN features.
+ * The restriction to NN features is essential since SP features can have non-
+ * predictable outcomes (depending on the remote configuration), and are inter-
+ * dependent (CCIDs for instance cause further dependencies).
+ */
+static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt,
+ u8 feat, u8 *val, u8 len)
+{
+ struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
+ const bool local = (opt == DCCPO_CONFIRM_R);
+ struct dccp_feat_entry *entry;
+ u8 type = dccp_feat_type(feat);
+ dccp_feat_val fval;
+
+ dccp_feat_print_opt(opt, feat, val, len, mandatory);
+
+ /* Ignore non-mandatory unknown and non-NN features */
+ if (type == FEAT_UNKNOWN) {
+ if (local && !mandatory)
+ return 0;
+ goto fast_path_unknown;
+ } else if (type != FEAT_NN) {
+ return 0;
+ }
+
+ /*
+ * We don't accept empty Confirms, since in fast-path feature
+ * negotiation the values are enabled immediately after sending
+ * the Change option.
+ * Empty Changes on the other hand are invalid (RFC 4340, 6.1).
+ */
+ if (len == 0 || len > sizeof(fval.nn))
+ goto fast_path_unknown;
+
+ if (opt == DCCPO_CHANGE_L) {
+ fval.nn = dccp_decode_value_var(val, len);
+ if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
+ goto fast_path_unknown;
+
+ if (dccp_feat_push_confirm(fn, feat, local, &fval) ||
+ dccp_feat_activate(sk, feat, local, &fval))
+ return DCCP_RESET_CODE_TOO_BUSY;
+
+ /* set the `Ack Pending' flag to piggyback a Confirm */
+ inet_csk_schedule_ack(sk);
+
+ } else if (opt == DCCPO_CONFIRM_R) {
+ entry = dccp_feat_list_lookup(fn, feat, local);
+ if (entry == NULL || entry->state != FEAT_CHANGING)
+ return 0;
+
+ fval.nn = dccp_decode_value_var(val, len);
+ if (fval.nn != entry->val.nn) {
+ DCCP_WARN("Bogus Confirm for non-existing value\n");
+ goto fast_path_failed;
+ }
+
+ /* It has been confirmed - so remove the entry */
+ dccp_feat_list_pop(entry);
+
+ } else {
+ DCCP_WARN("Received illegal option %u\n", opt);
+ goto fast_path_failed;
+ }
+ return 0;
+
+fast_path_unknown:
+ if (!mandatory)
+ return dccp_push_empty_confirm(fn, feat, local);
+
+fast_path_failed:
+ return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
+ : DCCP_RESET_CODE_OPTION_ERROR;
+}
+
+/**
* dccp_feat_parse_options - Process Feature-Negotiation Options
* @sk: for general use and used by the client during connection setup
* @dreq: used by the server during connection setup
@@ -1281,6 +1368,15 @@ int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
val, len, server);
}
+ break;
+ /*
+ * Support for exchanging NN options on an established connection
+ * This is currently restricted to Ack Ratio (RFC 4341, 6.1.2)
+ */
+ case DCCP_OPEN:
+ case DCCP_PARTOPEN:
+ return dccp_feat_handle_nn_established(sk, mandatory, opt, feat,
+ val, len);
}
return 0; /* ignore FN options in all other states */
}