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Congestion Control: add in RFC7252 configuration flexibility
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Create where appropriate default values for the Congestion control base
values and update the derived CC values accordingly.

Move derived value #define to coap_session_internal.h.

Update coap_session_t to hold the new CC values.

Update documentation for the new CC functions that update / get the
appropriate values.

NOTE: PROBING_WAIT is not currently checked in the code.
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@mrdeep1 @obgm
mrdeep1 authored and obgm committed Jun 17, 2022
1 parent 41afb92 commit 5a10ce4
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Showing 11 changed files with 364 additions and 152 deletions.
2 changes: 1 addition & 1 deletion examples/coap-client.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1819,7 +1819,7 @@ main(int argc, char **argv) {

if (is_mcast && wait_seconds == DEFAULT_WAIT_TIME)
/* Allow for other servers to respond within DEFAULT_LEISURE RFC7252 8.2 */
wait_seconds = COAP_DEFAULT_LEISURE;
wait_seconds = coap_session_get_default_leisure(session).integer_part;

wait_ms = wait_seconds * 1000;
coap_log(LOG_DEBUG, "timeout is set to %u seconds\n", wait_seconds);
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196 changes: 105 additions & 91 deletions include/coap3/coap_session.h
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Original file line number Diff line number Diff line change
Expand Up @@ -424,130 +424,77 @@ coap_session_t *coap_session_get_by_peer(const coap_context_t *ctx,
#define COAP_DEFAULT_ACK_RANDOM_FACTOR ((coap_fixed_point_t){1,500})

/**
* Number of message retransmissions before message sending is stopped
* Number of message retransmissions before message sending is stopped.
* RFC 7252, Section 4.8 Default value of MAX_RETRANSMIT is 4
*
* Configurable using coap_session_set_max_retransmit()
*/
#define COAP_DEFAULT_MAX_RETRANSMIT 4
#define COAP_DEFAULT_MAX_RETRANSMIT (4U)

/**
* The number of simultaneous outstanding interactions that a client
* maintains to a given server.
* RFC 7252, Section 4.8 Default value of NSTART is 1
*
* Configurable using coap_session_set_nstart()
*/
#define COAP_DEFAULT_NSTART 1

/**
* The maximum number of seconds before sending back a response to a
* multicast request.
* RFC 7252, Section 4.8 DEFAULT_LEISURE is 5.
*/
#ifndef COAP_DEFAULT_LEISURE
#define COAP_DEFAULT_LEISURE (5U)
#endif /* COAP_DEFAULT_LEISURE */
#define COAP_DEFAULT_NSTART (1U)

/**
* The MAX_TRANSMIT_SPAN definition for the session (s).
* The number of seconds to use as bounds for multicast traffic
* RFC 7252, Section 4.8 Default value of DEFAULT_LEISURE is 5.0
*
* RFC 7252, Section 4.8.2 Calculation of MAX_TRAMSMIT_SPAN
* ACK_TIMEOUT * ((2 ** (MAX_RETRANSMIT)) - 1) * ACK_RANDOM_FACTOR
* Configurable using coap_session_set_default_leisure()
*/
#define COAP_MAX_TRANSMIT_SPAN(s) \
((s->ack_timeout.integer_part * 1000 + s->ack_timeout.fractional_part) * \
((1 << (s->max_retransmit)) -1) * \
(s->ack_random_factor.integer_part * 1000 + \
s->ack_random_factor.fractional_part) \
/ 1000000)
#define COAP_DEFAULT_DEFAULT_LEISURE ((coap_fixed_point_t){5,0})

/**
* The MAX_TRANSMIT_WAIT definition for the session (s).
* The number of bytes/second allowed when there is no response
* RFC 7252, Section 4.8 Default value of PROBING_RATE is 1
*
* RFC 7252, Section 4.8.2 Calculation of MAX_TRAMSMIT_WAIT
* ACK_TIMEOUT * ((2 ** (MAX_RETRANSMIT + 1)) - 1) * ACK_RANDOM_FACTOR
* Configurable using coap_session_set_probing_rate()
*/
#define COAP_MAX_TRANSMIT_WAIT(s) \
((s->ack_timeout.integer_part * 1000 + s->ack_timeout.fractional_part) * \
((1 << (s->max_retransmit + 1)) -1) * \
(s->ack_random_factor.integer_part * 1000 + \
s->ack_random_factor.fractional_part) \
/ 1000000)
#define COAP_DEFAULT_PROBING_RATE (1U)

/**
* The MAX_LATENCY definition.
* RFC 7252, Section 4.8.2 MAX_LATENCY is 100.
*/
#define COAP_MAX_LATENCY 100

/**
* The PROCESSING_DELAY definition for the session (s).
*
* RFC 7252, Section 4.8.2 Calculation of PROCESSING_DELAY
* PROCESSING_DELAY set to ACK_TIMEOUT
*/
#define COAP_PROCESSING_DELAY(s) \
((s->ack_timeout.integer_part * 1000 + s->ack_timeout.fractional_part + 500) \
/ 1000)

/**
* The MAX_RTT definition for the session (s).
*
* RFC 7252, Section 4.8.2 Calculation of MAX_RTT
* (2 * MAX_LATENCY) + PROCESSING_DELAY
*/
#define COAP_MAX_RTT(s) \
((2 * COAP_MAX_LATENCY) + COAP_PROCESSING_DELAY(s))

/**
* The EXCHANGE_LIFETIME definition for the session (s).
*
* RFC 7252, Section 4.8.2 Calculation of EXCHANGE_LIFETIME
* MAX_TRANSMIT_SPAN + (2 * MAX_LATENCY) + PROCESSING_DELAY
*/
#define COAP_EXCHANGE_LIFETIME(s) \
(COAP_MAX_TRANSMIT_SPAN(s) + (2 * COAP_MAX_LATENCY) + COAP_PROCESSING_DELAY(s))

/**
* The NON_LIFETIME definition for the session (s).
*
* RFC 7252, Section 4.8.2 Calculation of NON_LIFETIME
* MAX_TRANSMIT_SPAN + MAX_LATENCY
*/
#define COAP_NON_LIFETIME(s) \
(COAP_MAX_TRANSMIT_SPAN(s) + COAP_MAX_LATENCY)

/** @} */
#define COAP_DEFAULT_MAX_LATENCY (100U)

/**
* Set the CoAP maximum retransmit count before failure
* Set the CoAP initial ack response timeout before the next re-transmit
*
* Number of message retransmissions before message sending is stopped
* Number of seconds when to expect an ACK or a response to an
* outstanding CON message.
* RFC7252 ACK_TIMEOUT
*
* @param session The CoAP session.
* @param value The value to set to. The default is 4 and should not normally
* @param value The value to set to. The default is 2.0 and should not normally
* get changed.
*/
void coap_session_set_max_retransmit(coap_session_t *session,
unsigned int value);
void coap_session_set_ack_timeout(coap_session_t *session,
coap_fixed_point_t value);

/**
* Set the CoAP initial ack response timeout before the next re-transmit
* Get the CoAP initial ack response timeout before the next re-transmit
*
* Number of seconds when to expect an ACK or a response to an
* outstanding CON message.
* RFC7252 ACK_TIMEOUT
*
* @param session The CoAP session.
* @param value The value to set to. The default is 2 and should not normally
* get changed.
*
* @return Current ack response timeout value
*/
void coap_session_set_ack_timeout(coap_session_t *session,
coap_fixed_point_t value);
coap_fixed_point_t coap_session_get_ack_timeout(const coap_session_t *session);

/**
* Set the CoAP ack randomize factor
*
* A factor that is used to randomize the wait time before a message
* is retransmitted to prevent synchronization effects.
* RFC7252 ACK_RANDOM_FACTOR
*
* @param session The CoAP session.
* @param value The value to set to. The default is 1.5 and should not normally
Expand All @@ -556,42 +503,109 @@ void coap_session_set_ack_timeout(coap_session_t *session,
void coap_session_set_ack_random_factor(coap_session_t *session,
coap_fixed_point_t value);

/**
* Get the CoAP ack randomize factor
*
* A factor that is used to randomize the wait time before a message
* is retransmitted to prevent synchronization effects.
* RFC7252 ACK_RANDOM_FACTOR
*
* @param session The CoAP session.
*
* @return Current ack randomize value
*/
coap_fixed_point_t coap_session_get_ack_random_factor(
const coap_session_t *session);

/**
* Set the CoAP maximum retransmit count before failure
*
* Number of message retransmissions before message sending is stopped
* RFC7252 MAX_RETRANSMIT
*
* @param session The CoAP session.
* @param value The value to set to. The default is 4 and should not normally
* get changed.
*/
void coap_session_set_max_retransmit(coap_session_t *session,
uint16_t value);

/**
* Get the CoAP maximum retransmit before failure
*
* Number of message retransmissions before message sending is stopped
* RFC7252 MAX_RETRANSMIT
*
* @param session The CoAP session.
*
* @return Current maximum retransmit value
*/
unsigned int coap_session_get_max_retransmit(const coap_session_t *session);
uint16_t coap_session_get_max_retransmit(const coap_session_t *session);

/**
* Get the CoAP initial ack response timeout before the next re-transmit
* Set the CoAP maximum concurrent transmission count of Confirmable messages
* RFC7252 NSTART
*
* Number of seconds when to expect an ACK or a response to an
* outstanding CON message.
* @param session The CoAP session.
* @param value The value to set to. The default is 1 and should not normally
* get changed.
*/
void coap_session_set_nstart(coap_session_t *session,
uint16_t value);

/**
* Get the CoAP maximum concurrent transmission count of Confirmable messages
* RFC7252 NSTART
*
* @param session The CoAP session.
*
* @return Current ack response timeout value
* @return Current nstart value
*/
coap_fixed_point_t coap_session_get_ack_timeout(const coap_session_t *session);
uint16_t coap_session_get_nstart(const coap_session_t *session);

/**
* Get the CoAP ack randomize factor
* Set the CoAP default leisure time (for multicast)
* RFC7252 DEFAULT_LEISURE
*
* A factor that is used to randomize the wait time before a message
* is retransmitted to prevent synchronization effects.
* @param session The CoAP session.
* @param value The value to set to. The default is 5.0 and should not normally
* get changed.
*/
void coap_session_set_default_leisure(coap_session_t *session,
coap_fixed_point_t value);

/**
* Get the CoAP default leisure time
* RFC7252 DEFAULT_LEISURE
*
* @param session The CoAP session.
*
* @return Current ack randomize value
* @return Current default_leisure value
*/
coap_fixed_point_t coap_session_get_ack_random_factor(
coap_fixed_point_t coap_session_get_default_leisure(
const coap_session_t *session);

/**
* Set the CoAP probing rate when there is no response
* RFC7252 PROBING_RATE
*
* @param session The CoAP session.
* @param value The value to set to. The default is 1 and should not normally
* get changed.
*/
void coap_session_set_probing_rate(coap_session_t *session, uint32_t value);

/**
* Get the CoAP probing rate when there is no response
* RFC7252 PROBING_RATE
*
* @param session The CoAP session.
*
* @return Current probing_rate value
*/
uint32_t coap_session_get_probing_rate(const coap_session_t *session);

/** @} */
/**
* Send a ping message for the session.
* @param session The CoAP session.
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