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Block1: Handle large FETCH with large blocked request and Observe
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Handle Observe cancellation with large blocked FETCH that needs to use
diffferent tokens when there is packet loss by checking the cache-key
if the token is not found (Q-Block1).

Let FETCH with Q-Block1 use NON now that cache-key is getting checked
if token mismatch.

Handle getting an unsolicited Observe response in the middle of
sending the FETCH blocks that ultimately will be doing the Observe
cancellation following re-assembly. (The unsolicited Observe token will
be the same token that is used to respond to the observe cancellation).
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@mrdeep1
mrdeep1 committed Jun 6, 2024
1 parent dec13f9 commit 0223c1a
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Showing 4 changed files with 128 additions and 57 deletions.
29 changes: 25 additions & 4 deletions include/coap3/coap_subscribe_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -105,7 +105,8 @@ coap_subscription_t *coap_add_observer(coap_resource_t *resource,
* @param resource The observed resource.
* @param session The observer's session
* @param token The token that identifies this subscription or @c NULL for
* any token.
* the first subscription.
*
* @return A valid subscription if exists or @c NULL otherwise.
*/
coap_subscription_t *coap_find_observer(coap_resource_t *resource,
Expand All @@ -125,20 +126,40 @@ void coap_touch_observer(coap_context_t *context,
const coap_bin_const_t *token);

/**
* Removes any subscription for @p observer from @p resource and releases the
* Removes any subscription for @p session observer from @p resource and releases the
* allocated storage. The result is @c 1 if an observation relationship with @p
* observer and @p token existed, @c 0 otherwise.
* session observer and @p token existed, @c 0 otherwise.
*
* @param resource The observed resource.
* @param session The observer's session.
* @param token The token that identifies this subscription or @c NULL for
* any token.
* the first subscription.
*
* @return @c 1 if the observer has been deleted, @c 0 otherwise.
*/
int coap_delete_observer(coap_resource_t *resource,
coap_session_t *session,
const coap_bin_const_t *token);

/**
* Removes any subscription for @p session observer from @p resource and releases the
* allocated storage. The result is @c 1 if an observation relationship with @p
* session observer and @p token existed, or cache-key derived from @p request matches,
* @c 0 otherwise.
*
* @param resource The observed resource.
* @param session The observer's session.
* @param token The token that identifies this subscription or @c NULL for
* the first subscription.
* @param request The requesting PDU.
*
* @return @c 1 if the observer has been deleted, @c 0 otherwise.
*/
int coap_delete_observer_request(coap_resource_t *resource,
coap_session_t *session,
const coap_bin_const_t *token,
coap_pdu_t *request);

/**
* Removes any subscription for @p session and releases the allocated storage.
*
Expand Down
64 changes: 44 additions & 20 deletions src/coap_block.c
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Original file line number Diff line number Diff line change
Expand Up @@ -494,18 +494,8 @@ coap_cancel_observe_lkd(coap_session_t *session, coap_binary_t *token,
lg_crcv->observe_set = 0;
if (pdu == NULL)
return 0;
#if COAP_Q_BLOCK_SUPPORT
if (pdu->code == COAP_REQUEST_CODE_FETCH && using_q_block1) {
/* Have to make sure all gets through in case of packet loss */
pdu->type = COAP_MESSAGE_CON;
} else {
/* Need to make sure that this is the correct requested type */
pdu->type = type;
}
#else /* ! COAP_Q_BLOCK_SUPPORT */
/* Need to make sure that this is the correct requested type */
pdu->type = type;
#endif /* ! COAP_Q_BLOCK_SUPPORT */

coap_update_option(pdu, COAP_OPTION_OBSERVE,
coap_encode_var_safe(buf, sizeof(buf),
Expand Down Expand Up @@ -2080,13 +2070,19 @@ track_fetch_observe(coap_pdu_t *pdu, coap_lg_crcv_t *lg_crcv,
coap_opt_length(opt));
if (observe_action == COAP_OBSERVE_ESTABLISH) {
/* Save the token in lg_crcv */
tmp = coap_realloc_type(COAP_STRING, lg_crcv->obs_token,
(block_num + 1) * sizeof(lg_crcv->obs_token[0]));
if (tmp == NULL)
return NULL;
lg_crcv->obs_token = tmp;
if (block_num + 1 == lg_crcv->obs_token_cnt)
coap_delete_bin_const(lg_crcv->obs_token[block_num]);
if (lg_crcv->obs_token_cnt <= block_num) {
size_t i;

tmp = coap_realloc_type(COAP_STRING, lg_crcv->obs_token,
(block_num + 1) * sizeof(lg_crcv->obs_token[0]));
if (tmp == NULL)
return NULL;
lg_crcv->obs_token = tmp;
for (i = lg_crcv->obs_token_cnt; i < block_num + 1; i++) {
lg_crcv->obs_token[i] = NULL;
}
}
coap_delete_bin_const(lg_crcv->obs_token[block_num]);

lg_crcv->obs_token_cnt = block_num + 1;
lg_crcv->obs_token[block_num] = coap_new_bin_const(token->s,
Expand All @@ -2096,9 +2092,7 @@ track_fetch_observe(coap_pdu_t *pdu, coap_lg_crcv_t *lg_crcv,
} else if (observe_action == COAP_OBSERVE_CANCEL) {
/* Use the token in lg_crcv */
if (block_num < lg_crcv->obs_token_cnt) {
if (lg_crcv->obs_token[block_num]) {
return lg_crcv->obs_token[block_num];
}
return lg_crcv->obs_token[block_num];
}
}
}
Expand Down Expand Up @@ -3457,6 +3451,36 @@ coap_handle_response_send_block(coap_session_t *session, coap_pdu_t *sent,
#endif /* ! COAP_Q_BLOCK_SUPPORT */
return 1;
}
} else if (COAP_RESPONSE_CLASS(rcvd->code) == 2) {
/*
* Not a block response asking for the next block.
* Could be an Observe response overlapping with block FETCH doing
* Observe cancellation.
*/
coap_opt_iterator_t opt_iter;
coap_opt_t *obs_opt;
int observe_action = -1;

if (p->pdu.code != COAP_REQUEST_CODE_FETCH) {
goto lg_xmit_finished;
}
obs_opt = coap_check_option(&p->pdu,
COAP_OPTION_OBSERVE,
&opt_iter);
if (obs_opt) {
observe_action = coap_decode_var_bytes(coap_opt_value(obs_opt),
coap_opt_length(obs_opt));
}
if (observe_action != COAP_OBSERVE_CANCEL) {
goto lg_xmit_finished;
}
obs_opt = coap_check_option(rcvd,
COAP_OPTION_OBSERVE,
&opt_iter);
if (obs_opt) {
return 0;
}
goto lg_xmit_finished;
} else if (rcvd->code == COAP_RESPONSE_CODE(401)) {
if (check_freshness(session, rcvd, sent, p, NULL))
return 1;
Expand Down
21 changes: 1 addition & 20 deletions src/coap_net.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1502,25 +1502,6 @@ coap_send_lkd(coap_session_t *session, coap_pdu_t *pdu) {
buf);
}
}
if (pdu->type == COAP_MESSAGE_NON && pdu->code == COAP_REQUEST_CODE_FETCH &&
coap_check_option(pdu, COAP_OPTION_OBSERVE, &opt_iter) &&
coap_check_option(pdu, COAP_OPTION_Q_BLOCK1, &opt_iter)) {
/* Issue with Fetch + Observe + Q-Block1 + NON if there are
* retransmits as potential for Token confusion */
pdu->type = COAP_MESSAGE_CON;
/* Need to update associated lg_xmit */
coap_lg_xmit_t *lg_xmit;

LL_FOREACH(session->lg_xmit, lg_xmit) {
if (lg_xmit->pdu.code == COAP_REQUEST_CODE_FETCH &&
lg_xmit->b.b1.app_token &&
coap_binary_equal(&pdu->actual_token, lg_xmit->b.b1.app_token)) {
/* Update as this is a Request */
lg_xmit->pdu.type = COAP_MESSAGE_CON;
break;
}
}
}
#endif /* COAP_Q_BLOCK_SUPPORT */

/*
Expand Down Expand Up @@ -3390,7 +3371,7 @@ handle_request(coap_context_t *context, coap_session_t *session, coap_pdu_t *pdu
buf);
}
} else if (observe_action == COAP_OBSERVE_CANCEL) {
coap_delete_observer(resource, session, &pdu->actual_token);
coap_delete_observer_request(resource, session, &pdu->actual_token, pdu);
} else {
coap_log_info("observe: unexpected action %d\n", observe_action);
}
Expand Down
71 changes: 58 additions & 13 deletions src/coap_resource.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -757,6 +757,10 @@ coap_find_observer_cache_key(coap_resource_t *resource, coap_session_t *session,
return NULL;
}

/* https://rfc-editor.org/rfc/rfc7641#section-3.6 */
static const uint16_t cache_ignore_options[] = { COAP_OPTION_ETAG,
COAP_OPTION_OSCORE
};
coap_subscription_t *
coap_add_observer(coap_resource_t *resource,
coap_session_t *session,
Expand All @@ -766,10 +770,6 @@ coap_add_observer(coap_resource_t *resource,
coap_cache_key_t *cache_key = NULL;
size_t len;
const uint8_t *data;
/* https://rfc-editor.org/rfc/rfc7641#section-3.6 */
static const uint16_t cache_ignore_options[] = { COAP_OPTION_ETAG,
COAP_OPTION_OSCORE
};

assert(session);

Expand Down Expand Up @@ -964,14 +964,13 @@ coap_touch_observer(coap_context_t *context, coap_session_t *session,
}
}

int
coap_delete_observer(coap_resource_t *resource, coap_session_t *session,
const coap_bin_const_t *token) {
coap_subscription_t *s;

s = coap_find_observer(resource, session, token);
static void
coap_delete_observer_internal(coap_resource_t *resource, coap_session_t *session,
coap_subscription_t *s) {
if (!s)
return;

if (s && coap_get_log_level() >= COAP_LOG_DEBUG) {
if (coap_get_log_level() >= COAP_LOG_DEBUG) {
char outbuf[2 * 8 + 1] = "";
unsigned int i;

Expand All @@ -985,21 +984,67 @@ coap_delete_observer(coap_resource_t *resource, coap_session_t *session,
(void *)s, outbuf, s->cache_key->key[0], s->cache_key->key[1],
s->cache_key->key[2], s-> cache_key->key[3]);
}
if (s && session->context->observe_deleted)
if (session->context->observe_deleted)
session->context->observe_deleted(session, s,
session->context->observe_user_data);

if (resource->subscribers && s) {
if (resource->subscribers) {
LL_DELETE(resource->subscribers, s);
coap_session_release_lkd(session);
coap_delete_pdu(s->pdu);
coap_delete_cache_key(s->cache_key);
coap_free_type(COAP_SUBSCRIPTION, s);
}

return;
}

int
coap_delete_observer(coap_resource_t *resource, coap_session_t *session,
const coap_bin_const_t *token) {
coap_subscription_t *s;

s = coap_find_observer(resource, session, token);
if (s)
coap_delete_observer_internal(resource, session, s);

return s != NULL;
}

int
coap_delete_observer_request(coap_resource_t *resource, coap_session_t *session,
const coap_bin_const_t *token, coap_pdu_t *request) {
coap_subscription_t *s;
int ret = 0;

s = coap_find_observer(resource, session, token);
s = NULL;
if (!s) {
/*
* It is possible that the client is using the wrong token.
* An example being a large FETCH spanning multiple blocks.
*/
coap_cache_key_t *cache_key;

cache_key = coap_cache_derive_key_w_ignore(session, request,
COAP_CACHE_IS_SESSION_BASED,
cache_ignore_options,
sizeof(cache_ignore_options)/sizeof(cache_ignore_options[0]));
if (cache_key) {
s = coap_find_observer_cache_key(resource, session, cache_key);
if (s) {
/* Delete entry with setup token */
ret = coap_delete_observer(resource, session, &s->pdu->actual_token);
}
coap_delete_cache_key(cache_key);
}
} else {
coap_delete_observer_internal(resource, session, s);
ret = 1;
}
return ret;
}

void
coap_delete_observers(coap_context_t *context, coap_session_t *session) {
RESOURCES_ITER(context->resources, resource) {
Expand Down

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