Coverage for aiocoap/numbers/constants.py: 95%

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1# SPDX-FileCopyrightText: Christian Amsüss and the aiocoap contributors 

2# 

3# SPDX-License-Identifier: MIT 

4 

5"""Constants either defined in the CoAP protocol (often default values for lack 

6of ways to determine eg. the estimated round trip time). Some parameters are 

7invented here for practical purposes of the implementation (eg. 

8DEFAULT_BLOCK_SIZE_EXP, EMPTY_ACK_DELAY).""" 

9 

10import warnings 

11import string 

12 

13COAP_PORT = 5683 

14"""The IANA-assigned standard port for COAP services.""" 

15 

16COAPS_PORT = 5684 

17 

18MCAST_IPV4_ALLCOAPNODES = "224.0.1.187" 

19MCAST_IPV6_LINKLOCAL_ALLNODES = "ff02::1" 

20MCAST_IPV6_LINKLOCAL_ALLCOAPNODES = "ff02::fd" 

21MCAST_IPV6_SITELOCAL_ALLNODES = "ff05::1" 

22MCAST_IPV6_SITELOCAL_ALLCOAPNODES = "ff05::fd" 

23MCAST_ALL = ( 

24 MCAST_IPV4_ALLCOAPNODES, 

25 MCAST_IPV6_LINKLOCAL_ALLNODES, 

26 MCAST_IPV6_LINKLOCAL_ALLCOAPNODES, 

27 MCAST_IPV6_SITELOCAL_ALLNODES, 

28 MCAST_IPV6_SITELOCAL_ALLCOAPNODES, 

29) 

30 

31MAX_REGULAR_BLOCK_SIZE_EXP = 6 

32 

33 

34class TransportTuning: 

35 """Base parameters that guide CoAP transport behaviors 

36 

37 The values in here are recommended values, often defaults from RFCs. They 

38 can be tuned in subclasses (and then passed into a message as 

39 ``transport_tuning``), although users should be aware that alteing some of 

40 these can cause the library to behave in ways violating the specification, 

41 especially with respect to congestion control. 

42 """ 

43 

44 # +-------------------+---------------+ 

45 # | name | default value | 

46 # +-------------------+---------------+ 

47 # | ACK_TIMEOUT | 2 seconds | 

48 # | ACK_RANDOM_FACTOR | 1.5 | 

49 # | MAX_RETRANSMIT | 4 | 

50 # | NSTART | 1 | 

51 # | DEFAULT_LEISURE | 5 seconds | 

52 # | PROBING_RATE | 1 Byte/second | 

53 # +-------------------+---------------+ 

54 

55 ACK_TIMEOUT = 2.0 

56 """The time, in seconds, to wait for an acknowledgement of a 

57 confirmable message. The inter-transmission time doubles 

58 for each retransmission.""" 

59 

60 ACK_RANDOM_FACTOR = 1.5 

61 """Timeout multiplier for anti-synchronization.""" 

62 

63 MAX_RETRANSMIT = 4 

64 """The number of retransmissions of confirmable messages to 

65 non-multicast endpoints before the infrastructure assumes no 

66 acknowledgement will be received.""" 

67 

68 NSTART = 1 

69 """Maximum number of simultaneous outstanding interactions 

70 that endpoint maintains to a given server (including proxies)""" 

71 

72 # +-------------------+---------------+ 

73 # | name | default value | 

74 # +-------------------+---------------+ 

75 # | MAX_TRANSMIT_SPAN | 45 s | 

76 # | MAX_TRANSMIT_WAIT | 93 s | 

77 # | MAX_LATENCY | 100 s | 

78 # | PROCESSING_DELAY | 2 s | 

79 # | MAX_RTT | 202 s | 

80 # | EXCHANGE_LIFETIME | 247 s | 

81 # | NON_LIFETIME | 145 s | 

82 # +-------------------+---------------+ 

83 

84 @property 

85 def MAX_TRANSMIT_SPAN(self): 

86 """Maximum time from the first transmission 

87 of a confirmable message to its last retransmission.""" 

88 return self.ACK_TIMEOUT * (2**self.MAX_RETRANSMIT - 1) * self.ACK_RANDOM_FACTOR 

89 

90 @property 

91 def MAX_TRANSMIT_WAIT(self): 

92 """Maximum time from the first transmission 

93 of a confirmable message to the time when the sender gives up on 

94 receiving an acknowledgement or reset.""" 

95 return ( 

96 self.ACK_TIMEOUT 

97 * (2 ** (self.MAX_RETRANSMIT + 1) - 1) 

98 * self.ACK_RANDOM_FACTOR 

99 ) 

100 

101 MAX_LATENCY = 100.0 

102 """Maximum time a datagram is expected to take from the start 

103 of its transmission to the completion of its reception.""" 

104 

105 @property 

106 def PROCESSING_DELAY(self): 

107 """ "Time a node takes to turn around a 

108 confirmable message into an acknowledgement.""" 

109 return self.ACK_TIMEOUT 

110 

111 @property 

112 def MAX_RTT(self): 

113 """Maximum round-trip time.""" 

114 return 2 * self.MAX_LATENCY + self.PROCESSING_DELAY 

115 

116 @property 

117 def EXCHANGE_LIFETIME(self): 

118 """time from starting to send a confirmable message to the time when an 

119 acknowledgement is no longer expected, i.e. message layer information about the 

120 message exchange can be purged""" 

121 return self.MAX_TRANSMIT_SPAN + self.MAX_RTT 

122 

123 DEFAULT_BLOCK_SIZE_EXP = MAX_REGULAR_BLOCK_SIZE_EXP 

124 """Default size exponent for blockwise transfers.""" 

125 

126 EMPTY_ACK_DELAY = 0.1 

127 """After this time protocol sends empty ACK, and separate response""" 

128 

129 REQUEST_TIMEOUT = MAX_TRANSMIT_WAIT 

130 """Time after which server assumes it won't receive any answer. 

131 It is not defined by IETF documents. 

132 For human-operated devices it might be preferable to set some small value 

133 (for example 10 seconds) 

134 For M2M it's application dependent.""" 

135 

136 DEFAULT_LEISURE = 5 

137 

138 @property 

139 def MULTICAST_REQUEST_TIMEOUT(self): 

140 return self.REQUEST_TIMEOUT + self.DEFAULT_LEISURE 

141 

142 OBSERVATION_RESET_TIME = 128 

143 """Time in seconds after which the value of the observe field are ignored. 

144 

145 This number is not explicitly named in RFC7641. 

146 """ 

147 

148 

149_default_transport_tuning = TransportTuning() 

150 

151 

152def __getattr__(name): 

153 if name[0] in string.ascii_uppercase and hasattr(_default_transport_tuning, name): 

154 warnings.warn( 

155 f"{name} is deprecated, use through the message's transport_tuning instead", 

156 DeprecationWarning, 

157 stacklevel=2, 

158 ) 

159 return getattr(_default_transport_tuning, name) 

160 raise AttributeError(f"module {__name__} has no attribute {name}") 

161 

162 

163SHUTDOWN_TIMEOUT = 3 

164"""Maximum time, in seconds, for which the process is kept around during shutdown""" 

165 

166__all__ = [ 

167 k for k in dir() if not k.startswith("_") and k not in ("warnings", "string") 

168]