dccp: support for exchanging of NN options in established state 2/2
This patch adds the receiver side and the (fast-path) activation part for dynamic changes of non-negotiable (NN) parameters in (PART)OPEN state. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: Samuel Jero <sj323707@ohio.edu> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.uk>
This commit is contained in:
Gerrit Renker
parent
d6916f87ca
commit
44e6fd9e67
116
net/dccp/feat.c
116
net/dccp/feat.c
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@ -344,6 +344,20 @@ static int __dccp_feat_activate(struct sock *sk, const int idx,
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return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
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}
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/**
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* dccp_feat_activate - Activate feature value on socket
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* @sk: fully connected DCCP socket (after handshake is complete)
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* @feat_num: feature to activate, one of %dccp_feature_numbers
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* @local: whether local (1) or remote (0) @feat_num is meant
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* @fval: the value (SP or NN) to activate, or NULL to use the default value
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* For general use this function is preferable over __dccp_feat_activate().
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*/
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static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local,
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dccp_feat_val const *fval)
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{
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return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval);
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}
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/* Test for "Req'd" feature (RFC 4340, 6.4) */
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static inline int dccp_feat_must_be_understood(u8 feat_num)
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{
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@ -1251,6 +1265,100 @@ confirmation_failed:
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: DCCP_RESET_CODE_OPTION_ERROR;
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}
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/**
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* dccp_feat_handle_nn_established - Fast-path reception of NN options
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* @sk: socket of an established DCCP connection
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* @mandatory: whether @opt was preceded by a Mandatory option
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* @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only)
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* @feat: NN number, one of %dccp_feature_numbers
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* @val: NN value
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* @len: length of @val in bytes
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* This function combines the functionality of change_recv/confirm_recv, with
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* the following differences (reset codes are the same):
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* - cleanup after receiving the Confirm;
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* - values are directly activated after successful parsing;
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* - deliberately restricted to NN features.
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* The restriction to NN features is essential since SP features can have non-
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* predictable outcomes (depending on the remote configuration), and are inter-
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* dependent (CCIDs for instance cause further dependencies).
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*/
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static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt,
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u8 feat, u8 *val, u8 len)
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{
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struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
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const bool local = (opt == DCCPO_CONFIRM_R);
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struct dccp_feat_entry *entry;
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u8 type = dccp_feat_type(feat);
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dccp_feat_val fval;
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dccp_feat_print_opt(opt, feat, val, len, mandatory);
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/* Ignore non-mandatory unknown and non-NN features */
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if (type == FEAT_UNKNOWN) {
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if (local && !mandatory)
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return 0;
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goto fast_path_unknown;
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} else if (type != FEAT_NN) {
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return 0;
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}
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/*
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* We don't accept empty Confirms, since in fast-path feature
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* negotiation the values are enabled immediately after sending
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* the Change option.
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* Empty Changes on the other hand are invalid (RFC 4340, 6.1).
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*/
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if (len == 0 || len > sizeof(fval.nn))
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goto fast_path_unknown;
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if (opt == DCCPO_CHANGE_L) {
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fval.nn = dccp_decode_value_var(val, len);
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if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
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goto fast_path_unknown;
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if (dccp_feat_push_confirm(fn, feat, local, &fval) ||
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dccp_feat_activate(sk, feat, local, &fval))
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return DCCP_RESET_CODE_TOO_BUSY;
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/* set the `Ack Pending' flag to piggyback a Confirm */
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inet_csk_schedule_ack(sk);
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} else if (opt == DCCPO_CONFIRM_R) {
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entry = dccp_feat_list_lookup(fn, feat, local);
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if (entry == NULL || entry->state != FEAT_CHANGING)
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return 0;
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fval.nn = dccp_decode_value_var(val, len);
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/*
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* Just ignore a value that doesn't match our current value.
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* If the option changes twice within two RTTs, then at least
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* one CONFIRM will be received for the old value after a
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* new CHANGE was sent.
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*/
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if (fval.nn != entry->val.nn)
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return 0;
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/* Only activate after receiving the Confirm option (6.6.1). */
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dccp_feat_activate(sk, feat, local, &fval);
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/* It has been confirmed - so remove the entry */
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dccp_feat_list_pop(entry);
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} else {
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DCCP_WARN("Received illegal option %u\n", opt);
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goto fast_path_failed;
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}
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return 0;
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fast_path_unknown:
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if (!mandatory)
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return dccp_push_empty_confirm(fn, feat, local);
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fast_path_failed:
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return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
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: DCCP_RESET_CODE_OPTION_ERROR;
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}
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/**
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* dccp_feat_parse_options - Process Feature-Negotiation Options
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* @sk: for general use and used by the client during connection setup
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@ -1286,6 +1394,14 @@ int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
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return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
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val, len, server);
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}
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break;
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/*
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* Support for exchanging NN options on an established connection.
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*/
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case DCCP_OPEN:
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case DCCP_PARTOPEN:
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return dccp_feat_handle_nn_established(sk, mandatory, opt, feat,
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val, len);
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}
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return 0; /* ignore FN options in all other states */
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}
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