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dccp: Processing Confirm options
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Analogous to the previous patch, this adds code to interpret incoming Confirm
feature-negotiation options. Both functions operate on the feature-negotiation
list of either the request_sock (server) or the dccp_sock (client).

Thanks to Wei Yongjun for pointing out that it is overly restrictive to check
the entire list of confirmed SP values.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Gerrit Renker authored and David S. Miller committed Dec 2, 2008
1 parent e77b836 commit b1ad004
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Showing 3 changed files with 101 additions and 17 deletions.
100 changes: 99 additions & 1 deletion net/dccp/feat.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,13 @@ static int dccp_feat_default_value(u8 feat_num)
return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
}

/* Test for "Req'd" feature (RFC 4340, 6.4) */
static inline int dccp_feat_must_be_understood(u8 feat_num)
{
return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
feat_num == DCCPF_SEQUENCE_WINDOW;
}

/* copy constructor, fval must not already contain allocated memory */
static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
{
Expand Down Expand Up @@ -1099,7 +1106,6 @@ int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
}

EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
#endif /* (later) */

int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
u8 *val, u8 len)
Expand Down Expand Up @@ -1154,6 +1160,7 @@ int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
}

EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
#endif /* (later) */

void dccp_feat_clean(struct dccp_minisock *dmsk)
{
Expand Down Expand Up @@ -1349,6 +1356,93 @@ static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
: DCCP_RESET_CODE_OPTION_ERROR;
}

/**
* dccp_feat_confirm_recv - Process received Confirm options
* @fn: feature-negotiation list to update
* @is_mandatory: whether @opt was preceded by a Mandatory option
* @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
* @feat: one of %dccp_feature_numbers
* @val: NN value or SP value/preference list
* @len: length of @val in bytes
* @server: whether this node is server (1) or client (0)
*/
static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
u8 feat, u8 *val, u8 len, const bool server)
{
u8 *plist, plen, type = dccp_feat_type(feat);
const bool local = (opt == DCCPO_CONFIRM_R);
struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);

if (entry == NULL) { /* nothing queued: ignore or handle error */
if (is_mandatory && type == FEAT_UNKNOWN)
return DCCP_RESET_CODE_MANDATORY_ERROR;

if (!local && type == FEAT_NN) /* 6.3.2 */
goto confirmation_failed;
return 0;
}

if (entry->state != FEAT_CHANGING) /* 6.6.2 */
return 0;

if (len == 0) {
if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
goto confirmation_failed;
/*
* Empty Confirm during connection setup: this means reverting
* to the `old' value, which in this case is the default. Since
* we handle default values automatically when no other values
* have been set, we revert to the old value by removing this
* entry from the list.
*/
dccp_feat_list_pop(entry);
return 0;
}

if (type == FEAT_NN) {
if (len > sizeof(entry->val.nn))
goto confirmation_failed;

if (entry->val.nn == dccp_decode_value_var(val, len))
goto confirmation_succeeded;

DCCP_WARN("Bogus Confirm for non-existing value\n");
goto confirmation_failed;
}

/*
* Parsing SP Confirms: the first element of @val is the preferred
* SP value which the peer confirms, the remainder depends on @len.
* Note that only the confirmed value need to be a valid SP value.
*/
if (!dccp_feat_is_valid_sp_val(feat, *val))
goto confirmation_failed;

if (len == 1) { /* peer didn't supply a preference list */
plist = val;
plen = len;
} else { /* preferred value + preference list */
plist = val + 1;
plen = len - 1;
}

/* Check whether the peer got the reconciliation right (6.6.8) */
if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
DCCP_WARN("Confirm selected the wrong value %u\n", *val);
return DCCP_RESET_CODE_OPTION_ERROR;
}
entry->val.sp.vec[0] = *val;

confirmation_succeeded:
entry->state = FEAT_STABLE;
return 0;

confirmation_failed:
DCCP_WARN("Confirmation failed\n");
return is_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
Expand Down Expand Up @@ -1379,6 +1473,10 @@ int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
case DCCPO_CHANGE_R:
return dccp_feat_change_recv(fn, mandatory, opt, feat,
val, len, server);
case DCCPO_CONFIRM_R:
case DCCPO_CONFIRM_L:
return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
val, len, server);
}
}
return 0; /* ignore FN options in all other states */
Expand Down
2 changes: 0 additions & 2 deletions net/dccp/feat.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -118,8 +118,6 @@ extern int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
extern int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);
extern int dccp_feat_parse_options(struct sock *, struct dccp_request_sock *,
u8 mand, u8 opt, u8 feat, u8 *val, u8 len);
extern int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
u8 *val, u8 len);
extern void dccp_feat_clean(struct dccp_minisock *dmsk);
extern int dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
extern int dccp_feat_clone_list(struct list_head const *, struct list_head *);
Expand Down
16 changes: 2 additions & 14 deletions net/dccp/options.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -134,26 +134,14 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
(unsigned long long)opt_recv->dccpor_ndp);
break;
case DCCPO_CHANGE_L:
case DCCPO_CHANGE_R:
if (pkt_type == DCCP_PKT_DATA)
case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
if (pkt_type == DCCP_PKT_DATA) /* RFC 4340, 6 */
break;
rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
*value, value + 1, len - 1);
if (rc)
goto out_featneg_failed;
break;
case DCCPO_CONFIRM_L:
/* fall through */
case DCCPO_CONFIRM_R:
if (pkt_type == DCCP_PKT_DATA)
break;
if (len < 2) /* FIXME this disallows empty confirm */
goto out_invalid_option;
if (dccp_feat_confirm_recv(sk, opt, *value,
value + 1, len - 1))
goto out_invalid_option;
break;
case DCCPO_ACK_VECTOR_0:
case DCCPO_ACK_VECTOR_1:
if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
Expand Down

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