1 | # -*- coding: utf-8 -*- |
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2 | """ |
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3 | ------------------------------------------------------------------------------ |
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4 | Mango 802.11 Reference Design Experiments Framework |
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5 | - Transport Unicast Ethernet IP/UDP Python Socket Implementation |
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6 | ------------------------------------------------------------------------------ |
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7 | License: Copyright 2019 Mango Communications, Inc. All rights reserved. |
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8 | Use and distribution subject to terms in LICENSE.txt |
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9 | ------------------------------------------------------------------------------ |
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10 | |
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11 | This module provides the unicast Ethernet IP/UDP transport based on the python |
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12 | socket class. |
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13 | |
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14 | Functions: |
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15 | TransportEthIpUdpPy() -- Unicast Ethernet UDP transport based on python |
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16 | sockets |
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17 | |
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18 | """ |
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19 | |
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20 | import re |
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21 | import time |
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22 | import socket |
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23 | |
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24 | from . import transport_eth_ip_udp as tp |
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25 | from . import exception as ex |
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26 | |
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27 | |
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28 | __all__ = ['TransportEthIpUdpPy'] |
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29 | |
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30 | |
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31 | class TransportEthIpUdpPy(tp.TransportEthIpUdp): |
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32 | """Class for Ethernet IP/UDP Transport class using Python libraries. |
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33 | |
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34 | Attributes: |
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35 | See TransportEthIpUdp for all attributes |
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36 | """ |
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37 | def __init__(self): |
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38 | super(TransportEthIpUdpPy, self).__init__() |
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39 | |
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40 | |
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41 | def send(self, payload, robust=True): |
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42 | """Send a message over the transport. |
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43 | |
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44 | Args: |
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45 | payload (bytes): Data to be sent over the socket |
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46 | robust (bool): Is a response required |
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47 | """ |
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48 | |
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49 | if robust: |
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50 | self.hdr.response_required() |
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51 | else: |
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52 | self.hdr.response_not_required() |
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53 | |
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54 | self.hdr.set_length(len(payload)) |
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55 | self.hdr.increment() |
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56 | |
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57 | # Assemble the packet from the transport header and payload |
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58 | # The wlan_exp C assumes the bytes starting at 'payload' here are u32 aligned |
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59 | # in the full Ethernet packet. The transport header is 10 bytes by design, |
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60 | # which aligns the end of the transport header to a 4-byte boundary when |
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61 | # appended to a 14-byte Ethernet + 20-byte IP + 8-byte UDP header |
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62 | # Different padding would be required here if the sizes of the headers |
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63 | # before the transport header change |
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64 | data = bytes(self.hdr.serialize() + payload) |
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65 | |
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66 | size = self.sock.sendto(data, (self.ip_address, self.unicast_port)) |
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67 | |
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68 | if size != len(data): |
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69 | print("Only {} of {} bytes of data sent".format(size, len(data))) |
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70 | |
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71 | |
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72 | def receive(self, timeout=None): |
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73 | """Return a response from the transport. |
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74 | |
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75 | Args: |
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76 | timeout (float): Time (in float seconds) to wait before raising |
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77 | an execption. If no value is specified, then it will use the |
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78 | default transport timeout (self.timeout) |
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79 | |
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80 | This function will block until a response is received or a timeout |
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81 | occurs. If a timeout occurs, it will raise a TransportError exception. |
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82 | """ |
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83 | reply = b'' |
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84 | |
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85 | if timeout is None: |
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86 | timeout = self.timeout |
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87 | else: |
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88 | timeout += self.timeout # Extend timeout to not run in to race conditions |
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89 | |
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90 | received_resp = 0 |
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91 | start_time = time.time() |
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92 | |
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93 | while received_resp == 0: |
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94 | recv_data = [] |
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95 | |
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96 | try: |
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97 | # Call the lowl-level socket recvfrom |
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98 | # Second return value is recv_addr, not used here |
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99 | # Size arg is set to larger than largest packet |
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100 | (recv_data, _) = self.sock.recvfrom(10000) |
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101 | |
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102 | except socket.error as err: |
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103 | expr = re.compile("timed out") |
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104 | if not expr.match(str(err)): |
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105 | print("Failed to receive UDP packet.\nError message:\n{}".format(err)) |
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106 | |
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107 | if len(recv_data) > 0: |
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108 | hdr_len = self.hdr.sizeof() |
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109 | # print("Received pkt from", recv_addr) |
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110 | if (self.hdr.is_reply(recv_data[0:hdr_len])): |
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111 | reply = recv_data[hdr_len:] |
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112 | received_resp = 1 |
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113 | |
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114 | if ((time.time() - start_time) > timeout ) and (received_resp == 0): |
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115 | raise ex.TransportError(self, "Transport receive timed out.") |
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116 | |
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117 | return reply |
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118 | |
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119 | |
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120 | def receive_nb(self): |
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121 | """Return a response from the transport. |
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122 | |
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123 | This function will not block and should be called in a polling loop |
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124 | until a response is received. |
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125 | """ |
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126 | reply = b'' |
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127 | recv_data = [] |
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128 | |
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129 | try: |
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130 | # Call the lowl-level socket recvfrom |
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131 | # Second return value is recv_addr, not used here |
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132 | # Size arg is set to larger than largest packet |
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133 | (recv_data, _) = self.sock.recvfrom(10000) |
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134 | except socket.error as err: |
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135 | expr = re.compile("timed out") |
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136 | if not expr.match(str(err)): |
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137 | print("Failed to receive UDP packet.\nError message:\n{}".format(err)) |
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138 | |
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139 | if len(recv_data) > 0: |
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140 | hdr_len = self.hdr.sizeof() |
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141 | if (self.hdr.is_reply(recv_data[0:hdr_len])): |
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142 | reply = recv_data[hdr_len:] |
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143 | |
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144 | return reply |
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145 | |
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146 | |
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147 | # End Class |
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