| /* | |
| ############################################################################### | |
| # | |
| # Temboo CoAP Edge Device library | |
| # | |
| # Copyright (C) 2017, Temboo Inc. | |
| # | |
| # Licensed under the Apache License, Version 2.0 (the "License"); | |
| # you may not use this file except in compliance with the License. | |
| # You may obtain a copy of the License at | |
| # | |
| # http://www.apache.org/licenses/LICENSE-2.0 | |
| # | |
| # Unless required by applicable law or agreed to in writing, | |
| # software distributed under the License is distributed on an | |
| # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, | |
| # either express or implied. See the License for the specific | |
| # language governing permissions and limitations under the License. | |
| # | |
| ############################################################################### | |
| */ | |
| /** | |
| * CoapMessageLayer is the lowest layer of the CoAP stack. It is responsible for | |
| * transmitting and receiving messages. Specifically, this implementation is | |
| * responsible for handling confirmable (CON) messages and their ACKs. | |
| * It is intended to implement the Message Layer FSM described by Kovatsch et al. in | |
| * https://tools.ietf.org/html/draft-kovatsch-lwig-coap-01 | |
| * | |
| * It can send reliable (confirmable or CON) messages and will maintain the necessary | |
| * state information to wait for an acknowledgement. It will handle any necessary | |
| * retransmissions and timeouts until a CON message has been ACK'd (or rejected.) | |
| * | |
| * It can not send unreliable (non-confirmable or NON) messages as currently designed | |
| * because our application does not use NON messages. | |
| * | |
| * It can receive CON and NON messages and will send ACKs or RESETs as required. | |
| * | |
| * Any non-rejected CON or NON messages received are passed up to the Request/Response | |
| * layer (CoapRRLayer) for processing. | |
| * | |
| * Be sure to note the difference between ACK's and Responses. This layer handles | |
| * ACK's, it does not handle Responses. (Responses are handled by the CoapRRLayer class.) | |
| */ | |
| class CoapMessageLayer { | |
| public: | |
| enum State { | |
| STATE_CLOSED, | |
| STATE_RELIABLE_TX, | |
| STATE_ACK_PENDING, | |
| STATE_WAITING_FOR_CON | |
| }; | |
| enum Result { | |
| NO_ERROR = 0, | |
| CON_RECEIVED, | |
| NON_RECEIVED, | |
| ACK_RECEIVED, | |
| RESET_RECEIVED, | |
| ERROR_IMPROPER_STATE, | |
| ERROR_NULL_MESSAGE, | |
| ERROR_SENDING_PACKET, | |
| ERROR_RECEIVING_PACKET, | |
| ERROR_RETRANSMIT_COUNT_EXCEEDED, | |
| ERROR_TX_SPAN_TIME_EXCEEDED | |
| }; | |
| static const uint32_t ACK_TIMEOUT = 2000; | |
| // MAX_ACK_TIMEOUT = ACK_TIMEOUT * ACK_RANDOM_FACTOR | |
| // RFC7252 suggests ACK_RANDOM_FACTOR = 1.5 | |
| static const uint32_t MAX_ACK_TIMEOUT = 3000; | |
| static const uint8_t MAX_RETRANSMIT = 4; | |
| // MAX_TRANSMIT_SPAN = ACK_TIMEOUT * ((2^MAX_RETRANSMIT) - 1) * ACK_RANDOM_FACTOR | |
| static const uint32_t MAX_TRANSMIT_SPAN = 45000; | |
| // MAX_TRANSMIT_WAIT = ACK_TIMEOUT * (2^(MAX_RETRANSMIT + 1) - 1) * ACK_RANDOM_FACTOR | |
| static const uint32_t MAX_TRANSMIT_WAIT = 93000; | |
| CoapMessageLayer(uint8_t* rxBuffer, uint16_t rxLen, TembooCoAPIPStack& ipStack); | |
| Result reliableSend(CoapMsg& msg, IPAddress destAddr, uint16_t destPort); | |
| Result cancelReliableSend(); | |
| Result acceptMsg(CoapMsg& msg); | |
| Result acceptMsg(CoapMsg& msg, IPAddress addr, uint16_t port); | |
| Result rejectMsg(CoapMsg& msg); | |
| Result rejectMsg(CoapMsg& msg, IPAddress addr, uint16_t port); | |
| Result loop(); | |
| Result getLastResult() {return m_lastResult;} | |
| uint16_t getRXByteCount() {return m_rxByteCount;} | |
| void setState(State state) {m_state = state;} | |
| private: | |
| uint8_t* m_rxBuffer; | |
| uint16_t m_rxLen; | |
| TembooCoAPIPStack& m_ipStack; | |
| State m_state; | |
| State m_prevState; | |
| int m_retransmitCount; | |
| Result m_lastResult; | |
| IPAddress m_destAddr; | |
| uint16_t m_destPort; | |
| uint16_t m_msgID; | |
| uint8_t* m_msgBytes; | |
| uint16_t m_msgLen; | |
| int32_t m_rxByteCount; | |
| TembooTimer m_txSpanTimer; | |
| TembooTimer m_retransmitTimer; | |
| uint32_t m_retransmitTimeoutMillis; | |
| }; | |