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dccp: support for exchanging of NN options in established state 2/2

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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 2011-07-24 20:27:59 -06:00
parent d6916f87ca
commit 44e6fd9e67
1 changed files with 116 additions and 0 deletions
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116
net/dccp/feat.c
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@ -344,6 +344,20 @@ static int __dccp_feat_activate(struct sock *sk, const int idx,
return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
}
/**
* dccp_feat_activate - Activate feature value on socket
* @sk: fully connected DCCP socket (after handshake is complete)
* @feat_num: feature to activate, one of %dccp_feature_numbers
* @local: whether local (1) or remote (0) @feat_num is meant
* @fval: the value (SP or NN) to activate, or NULL to use the default value
* For general use this function is preferable over __dccp_feat_activate().
*/
static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local,
dccp_feat_val const *fval)
{
return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval);
}
/* Test for "Req'd" feature (RFC 4340, 6.4) */
static inline int dccp_feat_must_be_understood(u8 feat_num)
{
@ -1251,6 +1265,100 @@ confirmation_failed:
: DCCP_RESET_CODE_OPTION_ERROR;
}
/**
* 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);
/*
* Just ignore a value that doesn't match our current value.
* If the option changes twice within two RTTs, then at least
* one CONFIRM will be received for the old value after a
* new CHANGE was sent.
*/
if (fval.nn != entry->val.nn)
return 0;
/* Only activate after receiving the Confirm option (6.6.1). */
dccp_feat_activate(sk, feat, local, &fval);
/* 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
@ -1286,6 +1394,14 @@ 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.
*/
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 */
}