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@@ -1,867 +1,867 b'' | |||
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1 | 1 | # wireprotoframing.py - unified framing protocol for wire protocol |
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2 | 2 | # |
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3 | 3 | # Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com> |
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4 | 4 | # |
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5 | 5 | # This software may be used and distributed according to the terms of the |
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6 | 6 | # GNU General Public License version 2 or any later version. |
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7 | 7 | |
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8 | 8 | # This file contains functionality to support the unified frame-based wire |
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9 | 9 | # protocol. For details about the protocol, see |
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10 | 10 | # `hg help internals.wireprotocol`. |
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11 | 11 | |
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12 | 12 | from __future__ import absolute_import |
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13 | 13 | |
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14 | 14 | import struct |
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15 | 15 | |
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16 | 16 | from .i18n import _ |
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17 | 17 | from .thirdparty import ( |
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18 | 18 | attr, |
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19 | 19 | cbor, |
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20 | 20 | ) |
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21 | 21 | from . import ( |
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22 | 22 | error, |
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23 | 23 | util, |
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24 | 24 | ) |
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25 | 25 | from .utils import ( |
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26 | 26 | stringutil, |
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27 | 27 | ) |
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28 | 28 | |
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29 | 29 | FRAME_HEADER_SIZE = 8 |
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30 | 30 | DEFAULT_MAX_FRAME_SIZE = 32768 |
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31 | 31 | |
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32 | 32 | STREAM_FLAG_BEGIN_STREAM = 0x01 |
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33 | 33 | STREAM_FLAG_END_STREAM = 0x02 |
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34 | 34 | STREAM_FLAG_ENCODING_APPLIED = 0x04 |
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35 | 35 | |
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36 | 36 | STREAM_FLAGS = { |
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37 | 37 | b'stream-begin': STREAM_FLAG_BEGIN_STREAM, |
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38 | 38 | b'stream-end': STREAM_FLAG_END_STREAM, |
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39 | 39 | b'encoded': STREAM_FLAG_ENCODING_APPLIED, |
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40 | 40 | } |
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41 | 41 | |
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42 | 42 | FRAME_TYPE_COMMAND_REQUEST = 0x01 |
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43 | 43 | FRAME_TYPE_COMMAND_DATA = 0x03 |
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44 | 44 | FRAME_TYPE_BYTES_RESPONSE = 0x04 |
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45 | 45 | FRAME_TYPE_ERROR_RESPONSE = 0x05 |
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46 | 46 | FRAME_TYPE_TEXT_OUTPUT = 0x06 |
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47 | 47 | FRAME_TYPE_PROGRESS = 0x07 |
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48 | 48 | FRAME_TYPE_STREAM_SETTINGS = 0x08 |
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49 | 49 | |
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50 | 50 | FRAME_TYPES = { |
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51 | 51 | b'command-request': FRAME_TYPE_COMMAND_REQUEST, |
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52 | 52 | b'command-data': FRAME_TYPE_COMMAND_DATA, |
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53 | 53 | b'bytes-response': FRAME_TYPE_BYTES_RESPONSE, |
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54 | 54 | b'error-response': FRAME_TYPE_ERROR_RESPONSE, |
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55 | 55 | b'text-output': FRAME_TYPE_TEXT_OUTPUT, |
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56 | 56 | b'progress': FRAME_TYPE_PROGRESS, |
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57 | 57 | b'stream-settings': FRAME_TYPE_STREAM_SETTINGS, |
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58 | 58 | } |
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59 | 59 | |
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60 | 60 | FLAG_COMMAND_REQUEST_NEW = 0x01 |
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61 | 61 | FLAG_COMMAND_REQUEST_CONTINUATION = 0x02 |
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62 | 62 | FLAG_COMMAND_REQUEST_MORE_FRAMES = 0x04 |
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63 | 63 | FLAG_COMMAND_REQUEST_EXPECT_DATA = 0x08 |
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64 | 64 | |
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65 | 65 | FLAGS_COMMAND_REQUEST = { |
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66 | 66 | b'new': FLAG_COMMAND_REQUEST_NEW, |
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67 | 67 | b'continuation': FLAG_COMMAND_REQUEST_CONTINUATION, |
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68 | 68 | b'more': FLAG_COMMAND_REQUEST_MORE_FRAMES, |
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69 | 69 | b'have-data': FLAG_COMMAND_REQUEST_EXPECT_DATA, |
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70 | 70 | } |
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71 | 71 | |
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72 | 72 | FLAG_COMMAND_DATA_CONTINUATION = 0x01 |
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73 | 73 | FLAG_COMMAND_DATA_EOS = 0x02 |
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74 | 74 | |
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75 | 75 | FLAGS_COMMAND_DATA = { |
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76 | 76 | b'continuation': FLAG_COMMAND_DATA_CONTINUATION, |
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77 | 77 | b'eos': FLAG_COMMAND_DATA_EOS, |
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78 | 78 | } |
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79 | 79 | |
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80 | 80 | FLAG_BYTES_RESPONSE_CONTINUATION = 0x01 |
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81 | 81 | FLAG_BYTES_RESPONSE_EOS = 0x02 |
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82 | 82 | FLAG_BYTES_RESPONSE_CBOR = 0x04 |
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83 | 83 | |
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84 | 84 | FLAGS_BYTES_RESPONSE = { |
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85 | 85 | b'continuation': FLAG_BYTES_RESPONSE_CONTINUATION, |
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86 | 86 | b'eos': FLAG_BYTES_RESPONSE_EOS, |
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87 | 87 | b'cbor': FLAG_BYTES_RESPONSE_CBOR, |
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88 | 88 | } |
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89 | 89 | |
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90 | 90 | FLAG_ERROR_RESPONSE_PROTOCOL = 0x01 |
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91 | 91 | FLAG_ERROR_RESPONSE_APPLICATION = 0x02 |
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92 | 92 | |
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93 | 93 | FLAGS_ERROR_RESPONSE = { |
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94 | 94 | b'protocol': FLAG_ERROR_RESPONSE_PROTOCOL, |
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95 | 95 | b'application': FLAG_ERROR_RESPONSE_APPLICATION, |
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96 | 96 | } |
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97 | 97 | |
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98 | 98 | # Maps frame types to their available flags. |
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99 | 99 | FRAME_TYPE_FLAGS = { |
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100 | 100 | FRAME_TYPE_COMMAND_REQUEST: FLAGS_COMMAND_REQUEST, |
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101 | 101 | FRAME_TYPE_COMMAND_DATA: FLAGS_COMMAND_DATA, |
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102 | 102 | FRAME_TYPE_BYTES_RESPONSE: FLAGS_BYTES_RESPONSE, |
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103 | 103 | FRAME_TYPE_ERROR_RESPONSE: FLAGS_ERROR_RESPONSE, |
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104 | 104 | FRAME_TYPE_TEXT_OUTPUT: {}, |
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105 | 105 | FRAME_TYPE_PROGRESS: {}, |
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106 | 106 | FRAME_TYPE_STREAM_SETTINGS: {}, |
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107 | 107 | } |
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108 | 108 | |
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109 | 109 | ARGUMENT_RECORD_HEADER = struct.Struct(r'<HH') |
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110 | 110 | |
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111 | 111 | def humanflags(mapping, value): |
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112 | 112 | """Convert a numeric flags value to a human value, using a mapping table.""" |
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113 | 113 | flags = [] |
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114 | 114 | for val, name in sorted({v: k for k, v in mapping.iteritems()}.iteritems()): |
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115 | 115 | if value & val: |
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116 | 116 | flags.append(name) |
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117 | 117 | |
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118 | 118 | return b'|'.join(flags) |
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119 | 119 | |
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120 | 120 | @attr.s(slots=True) |
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121 | 121 | class frameheader(object): |
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122 | 122 | """Represents the data in a frame header.""" |
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123 | 123 | |
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124 | 124 | length = attr.ib() |
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125 | 125 | requestid = attr.ib() |
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126 | 126 | streamid = attr.ib() |
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127 | 127 | streamflags = attr.ib() |
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128 | 128 | typeid = attr.ib() |
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129 | 129 | flags = attr.ib() |
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130 | 130 | |
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131 | 131 | @attr.s(slots=True, repr=False) |
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132 | 132 | class frame(object): |
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133 | 133 | """Represents a parsed frame.""" |
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134 | 134 | |
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135 | 135 | requestid = attr.ib() |
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136 | 136 | streamid = attr.ib() |
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137 | 137 | streamflags = attr.ib() |
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138 | 138 | typeid = attr.ib() |
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139 | 139 | flags = attr.ib() |
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140 | 140 | payload = attr.ib() |
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141 | 141 | |
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142 | 142 | def __repr__(self): |
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143 | 143 | typename = '<unknown>' |
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144 | 144 | for name, value in FRAME_TYPES.iteritems(): |
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145 | 145 | if value == self.typeid: |
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146 | 146 | typename = name |
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147 | 147 | break |
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148 | 148 | |
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149 | 149 | return ('frame(size=%d; request=%d; stream=%d; streamflags=%s; ' |
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150 | 150 | 'type=%s; flags=%s)' % ( |
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151 | 151 | len(self.payload), self.requestid, self.streamid, |
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152 | 152 | humanflags(STREAM_FLAGS, self.streamflags), typename, |
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153 |
humanflags(FRAME_TYPE_FLAGS |
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153 | humanflags(FRAME_TYPE_FLAGS.get(self.typeid, {}), self.flags))) | |
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154 | 154 | |
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155 | 155 | def makeframe(requestid, streamid, streamflags, typeid, flags, payload): |
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156 | 156 | """Assemble a frame into a byte array.""" |
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157 | 157 | # TODO assert size of payload. |
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158 | 158 | frame = bytearray(FRAME_HEADER_SIZE + len(payload)) |
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159 | 159 | |
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160 | 160 | # 24 bits length |
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161 | 161 | # 16 bits request id |
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162 | 162 | # 8 bits stream id |
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163 | 163 | # 8 bits stream flags |
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164 | 164 | # 4 bits type |
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165 | 165 | # 4 bits flags |
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166 | 166 | |
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167 | 167 | l = struct.pack(r'<I', len(payload)) |
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168 | 168 | frame[0:3] = l[0:3] |
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169 | 169 | struct.pack_into(r'<HBB', frame, 3, requestid, streamid, streamflags) |
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170 | 170 | frame[7] = (typeid << 4) | flags |
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171 | 171 | frame[8:] = payload |
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172 | 172 | |
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173 | 173 | return frame |
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174 | 174 | |
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175 | 175 | def makeframefromhumanstring(s): |
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176 | 176 | """Create a frame from a human readable string |
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177 | 177 | |
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178 | 178 | DANGER: NOT SAFE TO USE WITH UNTRUSTED INPUT BECAUSE OF POTENTIAL |
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179 | 179 | eval() USAGE. DO NOT USE IN CORE. |
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180 | 180 | |
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181 | 181 | Strings have the form: |
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182 | 182 | |
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183 | 183 | <request-id> <stream-id> <stream-flags> <type> <flags> <payload> |
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184 | 184 | |
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185 | 185 | This can be used by user-facing applications and tests for creating |
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186 | 186 | frames easily without having to type out a bunch of constants. |
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187 | 187 | |
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188 | 188 | Request ID and stream IDs are integers. |
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189 | 189 | |
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190 | 190 | Stream flags, frame type, and flags can be specified by integer or |
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191 | 191 | named constant. |
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192 | 192 | |
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193 | 193 | Flags can be delimited by `|` to bitwise OR them together. |
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194 | 194 | |
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195 | 195 | If the payload begins with ``cbor:``, the following string will be |
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196 | 196 | evaluated as Python code and the resulting object will be fed into |
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197 | 197 | a CBOR encoder. Otherwise, the payload is interpreted as a Python |
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198 | 198 | byte string literal. |
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199 | 199 | """ |
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200 | 200 | fields = s.split(b' ', 5) |
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201 | 201 | requestid, streamid, streamflags, frametype, frameflags, payload = fields |
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202 | 202 | |
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203 | 203 | requestid = int(requestid) |
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204 | 204 | streamid = int(streamid) |
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205 | 205 | |
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206 | 206 | finalstreamflags = 0 |
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207 | 207 | for flag in streamflags.split(b'|'): |
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208 | 208 | if flag in STREAM_FLAGS: |
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209 | 209 | finalstreamflags |= STREAM_FLAGS[flag] |
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210 | 210 | else: |
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211 | 211 | finalstreamflags |= int(flag) |
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212 | 212 | |
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213 | 213 | if frametype in FRAME_TYPES: |
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214 | 214 | frametype = FRAME_TYPES[frametype] |
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215 | 215 | else: |
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216 | 216 | frametype = int(frametype) |
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217 | 217 | |
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218 | 218 | finalflags = 0 |
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219 | 219 | validflags = FRAME_TYPE_FLAGS[frametype] |
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220 | 220 | for flag in frameflags.split(b'|'): |
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221 | 221 | if flag in validflags: |
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222 | 222 | finalflags |= validflags[flag] |
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223 | 223 | else: |
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224 | 224 | finalflags |= int(flag) |
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225 | 225 | |
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226 | 226 | if payload.startswith(b'cbor:'): |
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227 | 227 | payload = cbor.dumps(stringutil.evalpython(payload[5:]), canonical=True) |
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228 | 228 | |
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229 | 229 | else: |
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230 | 230 | payload = stringutil.unescapestr(payload) |
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231 | 231 | |
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232 | 232 | return makeframe(requestid=requestid, streamid=streamid, |
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233 | 233 | streamflags=finalstreamflags, typeid=frametype, |
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234 | 234 | flags=finalflags, payload=payload) |
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235 | 235 | |
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236 | 236 | def parseheader(data): |
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237 | 237 | """Parse a unified framing protocol frame header from a buffer. |
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238 | 238 | |
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239 | 239 | The header is expected to be in the buffer at offset 0 and the |
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240 | 240 | buffer is expected to be large enough to hold a full header. |
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241 | 241 | """ |
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242 | 242 | # 24 bits payload length (little endian) |
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243 | 243 | # 16 bits request ID |
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244 | 244 | # 8 bits stream ID |
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245 | 245 | # 8 bits stream flags |
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246 | 246 | # 4 bits frame type |
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247 | 247 | # 4 bits frame flags |
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248 | 248 | # ... payload |
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249 | 249 | framelength = data[0] + 256 * data[1] + 16384 * data[2] |
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250 | 250 | requestid, streamid, streamflags = struct.unpack_from(r'<HBB', data, 3) |
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251 | 251 | typeflags = data[7] |
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252 | 252 | |
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253 | 253 | frametype = (typeflags & 0xf0) >> 4 |
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254 | 254 | frameflags = typeflags & 0x0f |
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255 | 255 | |
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256 | 256 | return frameheader(framelength, requestid, streamid, streamflags, |
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257 | 257 | frametype, frameflags) |
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258 | 258 | |
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259 | 259 | def readframe(fh): |
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260 | 260 | """Read a unified framing protocol frame from a file object. |
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261 | 261 | |
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262 | 262 | Returns a 3-tuple of (type, flags, payload) for the decoded frame or |
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263 | 263 | None if no frame is available. May raise if a malformed frame is |
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264 | 264 | seen. |
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265 | 265 | """ |
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266 | 266 | header = bytearray(FRAME_HEADER_SIZE) |
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267 | 267 | |
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268 | 268 | readcount = fh.readinto(header) |
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269 | 269 | |
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270 | 270 | if readcount == 0: |
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271 | 271 | return None |
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272 | 272 | |
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273 | 273 | if readcount != FRAME_HEADER_SIZE: |
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274 | 274 | raise error.Abort(_('received incomplete frame: got %d bytes: %s') % |
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275 | 275 | (readcount, header)) |
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276 | 276 | |
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277 | 277 | h = parseheader(header) |
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278 | 278 | |
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279 | 279 | payload = fh.read(h.length) |
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280 | 280 | if len(payload) != h.length: |
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281 | 281 | raise error.Abort(_('frame length error: expected %d; got %d') % |
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282 | 282 | (h.length, len(payload))) |
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283 | 283 | |
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284 | 284 | return frame(h.requestid, h.streamid, h.streamflags, h.typeid, h.flags, |
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285 | 285 | payload) |
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286 | 286 | |
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287 | 287 | def createcommandframes(stream, requestid, cmd, args, datafh=None, |
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288 | 288 | maxframesize=DEFAULT_MAX_FRAME_SIZE): |
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289 | 289 | """Create frames necessary to transmit a request to run a command. |
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290 | 290 | |
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291 | 291 | This is a generator of bytearrays. Each item represents a frame |
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292 | 292 | ready to be sent over the wire to a peer. |
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293 | 293 | """ |
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294 | 294 | data = {b'name': cmd} |
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295 | 295 | if args: |
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296 | 296 | data[b'args'] = args |
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297 | 297 | |
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298 | 298 | data = cbor.dumps(data, canonical=True) |
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299 | 299 | |
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300 | 300 | offset = 0 |
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301 | 301 | |
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302 | 302 | while True: |
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303 | 303 | flags = 0 |
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304 | 304 | |
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305 | 305 | # Must set new or continuation flag. |
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306 | 306 | if not offset: |
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307 | 307 | flags |= FLAG_COMMAND_REQUEST_NEW |
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308 | 308 | else: |
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309 | 309 | flags |= FLAG_COMMAND_REQUEST_CONTINUATION |
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310 | 310 | |
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311 | 311 | # Data frames is set on all frames. |
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312 | 312 | if datafh: |
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313 | 313 | flags |= FLAG_COMMAND_REQUEST_EXPECT_DATA |
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314 | 314 | |
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315 | 315 | payload = data[offset:offset + maxframesize] |
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316 | 316 | offset += len(payload) |
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317 | 317 | |
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318 | 318 | if len(payload) == maxframesize and offset < len(data): |
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319 | 319 | flags |= FLAG_COMMAND_REQUEST_MORE_FRAMES |
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320 | 320 | |
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321 | 321 | yield stream.makeframe(requestid=requestid, |
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322 | 322 | typeid=FRAME_TYPE_COMMAND_REQUEST, |
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323 | 323 | flags=flags, |
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324 | 324 | payload=payload) |
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325 | 325 | |
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326 | 326 | if not (flags & FLAG_COMMAND_REQUEST_MORE_FRAMES): |
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327 | 327 | break |
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328 | 328 | |
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329 | 329 | if datafh: |
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330 | 330 | while True: |
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331 | 331 | data = datafh.read(DEFAULT_MAX_FRAME_SIZE) |
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332 | 332 | |
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333 | 333 | done = False |
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334 | 334 | if len(data) == DEFAULT_MAX_FRAME_SIZE: |
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335 | 335 | flags = FLAG_COMMAND_DATA_CONTINUATION |
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336 | 336 | else: |
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337 | 337 | flags = FLAG_COMMAND_DATA_EOS |
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338 | 338 | assert datafh.read(1) == b'' |
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339 | 339 | done = True |
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340 | 340 | |
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341 | 341 | yield stream.makeframe(requestid=requestid, |
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342 | 342 | typeid=FRAME_TYPE_COMMAND_DATA, |
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343 | 343 | flags=flags, |
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344 | 344 | payload=data) |
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345 | 345 | |
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346 | 346 | if done: |
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347 | 347 | break |
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348 | 348 | |
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349 | 349 | def createbytesresponseframesfrombytes(stream, requestid, data, |
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350 | 350 | maxframesize=DEFAULT_MAX_FRAME_SIZE): |
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351 | 351 | """Create a raw frame to send a bytes response from static bytes input. |
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352 | 352 | |
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353 | 353 | Returns a generator of bytearrays. |
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354 | 354 | """ |
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355 | 355 | |
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356 | 356 | # Simple case of a single frame. |
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357 | 357 | if len(data) <= maxframesize: |
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358 | 358 | yield stream.makeframe(requestid=requestid, |
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359 | 359 | typeid=FRAME_TYPE_BYTES_RESPONSE, |
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360 | 360 | flags=FLAG_BYTES_RESPONSE_EOS, |
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361 | 361 | payload=data) |
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362 | 362 | return |
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363 | 363 | |
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364 | 364 | offset = 0 |
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365 | 365 | while True: |
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366 | 366 | chunk = data[offset:offset + maxframesize] |
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367 | 367 | offset += len(chunk) |
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368 | 368 | done = offset == len(data) |
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369 | 369 | |
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370 | 370 | if done: |
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371 | 371 | flags = FLAG_BYTES_RESPONSE_EOS |
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372 | 372 | else: |
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373 | 373 | flags = FLAG_BYTES_RESPONSE_CONTINUATION |
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374 | 374 | |
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375 | 375 | yield stream.makeframe(requestid=requestid, |
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376 | 376 | typeid=FRAME_TYPE_BYTES_RESPONSE, |
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377 | 377 | flags=flags, |
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378 | 378 | payload=chunk) |
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379 | 379 | |
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380 | 380 | if done: |
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381 | 381 | break |
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382 | 382 | |
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383 | 383 | def createerrorframe(stream, requestid, msg, protocol=False, application=False): |
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384 | 384 | # TODO properly handle frame size limits. |
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385 | 385 | assert len(msg) <= DEFAULT_MAX_FRAME_SIZE |
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386 | 386 | |
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387 | 387 | flags = 0 |
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388 | 388 | if protocol: |
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389 | 389 | flags |= FLAG_ERROR_RESPONSE_PROTOCOL |
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390 | 390 | if application: |
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391 | 391 | flags |= FLAG_ERROR_RESPONSE_APPLICATION |
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392 | 392 | |
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393 | 393 | yield stream.makeframe(requestid=requestid, |
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394 | 394 | typeid=FRAME_TYPE_ERROR_RESPONSE, |
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395 | 395 | flags=flags, |
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396 | 396 | payload=msg) |
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397 | 397 | |
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398 | 398 | def createtextoutputframe(stream, requestid, atoms, |
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399 | 399 | maxframesize=DEFAULT_MAX_FRAME_SIZE): |
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400 | 400 | """Create a text output frame to render text to people. |
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401 | 401 | |
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402 | 402 | ``atoms`` is a 3-tuple of (formatting string, args, labels). |
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403 | 403 | |
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404 | 404 | The formatting string contains ``%s`` tokens to be replaced by the |
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405 | 405 | corresponding indexed entry in ``args``. ``labels`` is an iterable of |
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406 | 406 | formatters to be applied at rendering time. In terms of the ``ui`` |
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407 | 407 | class, each atom corresponds to a ``ui.write()``. |
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408 | 408 | """ |
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409 | 409 | atomdicts = [] |
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410 | 410 | |
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411 | 411 | for (formatting, args, labels) in atoms: |
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412 | 412 | # TODO look for localstr, other types here? |
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413 | 413 | |
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414 | 414 | if not isinstance(formatting, bytes): |
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415 | 415 | raise ValueError('must use bytes formatting strings') |
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416 | 416 | for arg in args: |
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417 | 417 | if not isinstance(arg, bytes): |
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418 | 418 | raise ValueError('must use bytes for arguments') |
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419 | 419 | for label in labels: |
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420 | 420 | if not isinstance(label, bytes): |
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421 | 421 | raise ValueError('must use bytes for labels') |
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422 | 422 | |
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423 | 423 | # Formatting string must be ASCII. |
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424 | 424 | formatting = formatting.decode(r'ascii', r'replace').encode(r'ascii') |
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425 | 425 | |
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426 | 426 | # Arguments must be UTF-8. |
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427 | 427 | args = [a.decode(r'utf-8', r'replace').encode(r'utf-8') for a in args] |
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428 | 428 | |
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429 | 429 | # Labels must be ASCII. |
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430 | 430 | labels = [l.decode(r'ascii', r'strict').encode(r'ascii') |
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431 | 431 | for l in labels] |
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432 | 432 | |
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433 | 433 | atom = {b'msg': formatting} |
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434 | 434 | if args: |
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435 | 435 | atom[b'args'] = args |
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436 | 436 | if labels: |
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437 | 437 | atom[b'labels'] = labels |
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438 | 438 | |
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439 | 439 | atomdicts.append(atom) |
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440 | 440 | |
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441 | 441 | payload = cbor.dumps(atomdicts, canonical=True) |
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442 | 442 | |
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443 | 443 | if len(payload) > maxframesize: |
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444 | 444 | raise ValueError('cannot encode data in a single frame') |
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445 | 445 | |
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446 | 446 | yield stream.makeframe(requestid=requestid, |
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447 | 447 | typeid=FRAME_TYPE_TEXT_OUTPUT, |
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448 | 448 | flags=0, |
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449 | 449 | payload=payload) |
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450 | 450 | |
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451 | 451 | class stream(object): |
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452 | 452 | """Represents a logical unidirectional series of frames.""" |
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453 | 453 | |
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454 | 454 | def __init__(self, streamid, active=False): |
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455 | 455 | self.streamid = streamid |
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456 | 456 | self._active = False |
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457 | 457 | |
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458 | 458 | def makeframe(self, requestid, typeid, flags, payload): |
|
459 | 459 | """Create a frame to be sent out over this stream. |
|
460 | 460 | |
|
461 | 461 | Only returns the frame instance. Does not actually send it. |
|
462 | 462 | """ |
|
463 | 463 | streamflags = 0 |
|
464 | 464 | if not self._active: |
|
465 | 465 | streamflags |= STREAM_FLAG_BEGIN_STREAM |
|
466 | 466 | self._active = True |
|
467 | 467 | |
|
468 | 468 | return makeframe(requestid, self.streamid, streamflags, typeid, flags, |
|
469 | 469 | payload) |
|
470 | 470 | |
|
471 | 471 | def ensureserverstream(stream): |
|
472 | 472 | if stream.streamid % 2: |
|
473 | 473 | raise error.ProgrammingError('server should only write to even ' |
|
474 | 474 | 'numbered streams; %d is not even' % |
|
475 | 475 | stream.streamid) |
|
476 | 476 | |
|
477 | 477 | class serverreactor(object): |
|
478 | 478 | """Holds state of a server handling frame-based protocol requests. |
|
479 | 479 | |
|
480 | 480 | This class is the "brain" of the unified frame-based protocol server |
|
481 | 481 | component. While the protocol is stateless from the perspective of |
|
482 | 482 | requests/commands, something needs to track which frames have been |
|
483 | 483 | received, what frames to expect, etc. This class is that thing. |
|
484 | 484 | |
|
485 | 485 | Instances are modeled as a state machine of sorts. Instances are also |
|
486 | 486 | reactionary to external events. The point of this class is to encapsulate |
|
487 | 487 | the state of the connection and the exchange of frames, not to perform |
|
488 | 488 | work. Instead, callers tell this class when something occurs, like a |
|
489 | 489 | frame arriving. If that activity is worthy of a follow-up action (say |
|
490 | 490 | *run a command*), the return value of that handler will say so. |
|
491 | 491 | |
|
492 | 492 | I/O and CPU intensive operations are purposefully delegated outside of |
|
493 | 493 | this class. |
|
494 | 494 | |
|
495 | 495 | Consumers are expected to tell instances when events occur. They do so by |
|
496 | 496 | calling the various ``on*`` methods. These methods return a 2-tuple |
|
497 | 497 | describing any follow-up action(s) to take. The first element is the |
|
498 | 498 | name of an action to perform. The second is a data structure (usually |
|
499 | 499 | a dict) specific to that action that contains more information. e.g. |
|
500 | 500 | if the server wants to send frames back to the client, the data structure |
|
501 | 501 | will contain a reference to those frames. |
|
502 | 502 | |
|
503 | 503 | Valid actions that consumers can be instructed to take are: |
|
504 | 504 | |
|
505 | 505 | sendframes |
|
506 | 506 | Indicates that frames should be sent to the client. The ``framegen`` |
|
507 | 507 | key contains a generator of frames that should be sent. The server |
|
508 | 508 | assumes that all frames are sent to the client. |
|
509 | 509 | |
|
510 | 510 | error |
|
511 | 511 | Indicates that an error occurred. Consumer should probably abort. |
|
512 | 512 | |
|
513 | 513 | runcommand |
|
514 | 514 | Indicates that the consumer should run a wire protocol command. Details |
|
515 | 515 | of the command to run are given in the data structure. |
|
516 | 516 | |
|
517 | 517 | wantframe |
|
518 | 518 | Indicates that nothing of interest happened and the server is waiting on |
|
519 | 519 | more frames from the client before anything interesting can be done. |
|
520 | 520 | |
|
521 | 521 | noop |
|
522 | 522 | Indicates no additional action is required. |
|
523 | 523 | |
|
524 | 524 | Known Issues |
|
525 | 525 | ------------ |
|
526 | 526 | |
|
527 | 527 | There are no limits to the number of partially received commands or their |
|
528 | 528 | size. A malicious client could stream command request data and exhaust the |
|
529 | 529 | server's memory. |
|
530 | 530 | |
|
531 | 531 | Partially received commands are not acted upon when end of input is |
|
532 | 532 | reached. Should the server error if it receives a partial request? |
|
533 | 533 | Should the client send a message to abort a partially transmitted request |
|
534 | 534 | to facilitate graceful shutdown? |
|
535 | 535 | |
|
536 | 536 | Active requests that haven't been responded to aren't tracked. This means |
|
537 | 537 | that if we receive a command and instruct its dispatch, another command |
|
538 | 538 | with its request ID can come in over the wire and there will be a race |
|
539 | 539 | between who responds to what. |
|
540 | 540 | """ |
|
541 | 541 | |
|
542 | 542 | def __init__(self, deferoutput=False): |
|
543 | 543 | """Construct a new server reactor. |
|
544 | 544 | |
|
545 | 545 | ``deferoutput`` can be used to indicate that no output frames should be |
|
546 | 546 | instructed to be sent until input has been exhausted. In this mode, |
|
547 | 547 | events that would normally generate output frames (such as a command |
|
548 | 548 | response being ready) will instead defer instructing the consumer to |
|
549 | 549 | send those frames. This is useful for half-duplex transports where the |
|
550 | 550 | sender cannot receive until all data has been transmitted. |
|
551 | 551 | """ |
|
552 | 552 | self._deferoutput = deferoutput |
|
553 | 553 | self._state = 'idle' |
|
554 | 554 | self._nextoutgoingstreamid = 2 |
|
555 | 555 | self._bufferedframegens = [] |
|
556 | 556 | # stream id -> stream instance for all active streams from the client. |
|
557 | 557 | self._incomingstreams = {} |
|
558 | 558 | self._outgoingstreams = {} |
|
559 | 559 | # request id -> dict of commands that are actively being received. |
|
560 | 560 | self._receivingcommands = {} |
|
561 | 561 | # Request IDs that have been received and are actively being processed. |
|
562 | 562 | # Once all output for a request has been sent, it is removed from this |
|
563 | 563 | # set. |
|
564 | 564 | self._activecommands = set() |
|
565 | 565 | |
|
566 | 566 | def onframerecv(self, frame): |
|
567 | 567 | """Process a frame that has been received off the wire. |
|
568 | 568 | |
|
569 | 569 | Returns a dict with an ``action`` key that details what action, |
|
570 | 570 | if any, the consumer should take next. |
|
571 | 571 | """ |
|
572 | 572 | if not frame.streamid % 2: |
|
573 | 573 | self._state = 'errored' |
|
574 | 574 | return self._makeerrorresult( |
|
575 | 575 | _('received frame with even numbered stream ID: %d') % |
|
576 | 576 | frame.streamid) |
|
577 | 577 | |
|
578 | 578 | if frame.streamid not in self._incomingstreams: |
|
579 | 579 | if not frame.streamflags & STREAM_FLAG_BEGIN_STREAM: |
|
580 | 580 | self._state = 'errored' |
|
581 | 581 | return self._makeerrorresult( |
|
582 | 582 | _('received frame on unknown inactive stream without ' |
|
583 | 583 | 'beginning of stream flag set')) |
|
584 | 584 | |
|
585 | 585 | self._incomingstreams[frame.streamid] = stream(frame.streamid) |
|
586 | 586 | |
|
587 | 587 | if frame.streamflags & STREAM_FLAG_ENCODING_APPLIED: |
|
588 | 588 | # TODO handle decoding frames |
|
589 | 589 | self._state = 'errored' |
|
590 | 590 | raise error.ProgrammingError('support for decoding stream payloads ' |
|
591 | 591 | 'not yet implemented') |
|
592 | 592 | |
|
593 | 593 | if frame.streamflags & STREAM_FLAG_END_STREAM: |
|
594 | 594 | del self._incomingstreams[frame.streamid] |
|
595 | 595 | |
|
596 | 596 | handlers = { |
|
597 | 597 | 'idle': self._onframeidle, |
|
598 | 598 | 'command-receiving': self._onframecommandreceiving, |
|
599 | 599 | 'errored': self._onframeerrored, |
|
600 | 600 | } |
|
601 | 601 | |
|
602 | 602 | meth = handlers.get(self._state) |
|
603 | 603 | if not meth: |
|
604 | 604 | raise error.ProgrammingError('unhandled state: %s' % self._state) |
|
605 | 605 | |
|
606 | 606 | return meth(frame) |
|
607 | 607 | |
|
608 | 608 | def onbytesresponseready(self, stream, requestid, data): |
|
609 | 609 | """Signal that a bytes response is ready to be sent to the client. |
|
610 | 610 | |
|
611 | 611 | The raw bytes response is passed as an argument. |
|
612 | 612 | """ |
|
613 | 613 | ensureserverstream(stream) |
|
614 | 614 | |
|
615 | 615 | def sendframes(): |
|
616 | 616 | for frame in createbytesresponseframesfrombytes(stream, requestid, |
|
617 | 617 | data): |
|
618 | 618 | yield frame |
|
619 | 619 | |
|
620 | 620 | self._activecommands.remove(requestid) |
|
621 | 621 | |
|
622 | 622 | result = sendframes() |
|
623 | 623 | |
|
624 | 624 | if self._deferoutput: |
|
625 | 625 | self._bufferedframegens.append(result) |
|
626 | 626 | return 'noop', {} |
|
627 | 627 | else: |
|
628 | 628 | return 'sendframes', { |
|
629 | 629 | 'framegen': result, |
|
630 | 630 | } |
|
631 | 631 | |
|
632 | 632 | def oninputeof(self): |
|
633 | 633 | """Signals that end of input has been received. |
|
634 | 634 | |
|
635 | 635 | No more frames will be received. All pending activity should be |
|
636 | 636 | completed. |
|
637 | 637 | """ |
|
638 | 638 | # TODO should we do anything about in-flight commands? |
|
639 | 639 | |
|
640 | 640 | if not self._deferoutput or not self._bufferedframegens: |
|
641 | 641 | return 'noop', {} |
|
642 | 642 | |
|
643 | 643 | # If we buffered all our responses, emit those. |
|
644 | 644 | def makegen(): |
|
645 | 645 | for gen in self._bufferedframegens: |
|
646 | 646 | for frame in gen: |
|
647 | 647 | yield frame |
|
648 | 648 | |
|
649 | 649 | return 'sendframes', { |
|
650 | 650 | 'framegen': makegen(), |
|
651 | 651 | } |
|
652 | 652 | |
|
653 | 653 | def onapplicationerror(self, stream, requestid, msg): |
|
654 | 654 | ensureserverstream(stream) |
|
655 | 655 | |
|
656 | 656 | return 'sendframes', { |
|
657 | 657 | 'framegen': createerrorframe(stream, requestid, msg, |
|
658 | 658 | application=True), |
|
659 | 659 | } |
|
660 | 660 | |
|
661 | 661 | def makeoutputstream(self): |
|
662 | 662 | """Create a stream to be used for sending data to the client.""" |
|
663 | 663 | streamid = self._nextoutgoingstreamid |
|
664 | 664 | self._nextoutgoingstreamid += 2 |
|
665 | 665 | |
|
666 | 666 | s = stream(streamid) |
|
667 | 667 | self._outgoingstreams[streamid] = s |
|
668 | 668 | |
|
669 | 669 | return s |
|
670 | 670 | |
|
671 | 671 | def _makeerrorresult(self, msg): |
|
672 | 672 | return 'error', { |
|
673 | 673 | 'message': msg, |
|
674 | 674 | } |
|
675 | 675 | |
|
676 | 676 | def _makeruncommandresult(self, requestid): |
|
677 | 677 | entry = self._receivingcommands[requestid] |
|
678 | 678 | |
|
679 | 679 | if not entry['requestdone']: |
|
680 | 680 | self._state = 'errored' |
|
681 | 681 | raise error.ProgrammingError('should not be called without ' |
|
682 | 682 | 'requestdone set') |
|
683 | 683 | |
|
684 | 684 | del self._receivingcommands[requestid] |
|
685 | 685 | |
|
686 | 686 | if self._receivingcommands: |
|
687 | 687 | self._state = 'command-receiving' |
|
688 | 688 | else: |
|
689 | 689 | self._state = 'idle' |
|
690 | 690 | |
|
691 | 691 | # Decode the payloads as CBOR. |
|
692 | 692 | entry['payload'].seek(0) |
|
693 | 693 | request = cbor.load(entry['payload']) |
|
694 | 694 | |
|
695 | 695 | if b'name' not in request: |
|
696 | 696 | self._state = 'errored' |
|
697 | 697 | return self._makeerrorresult( |
|
698 | 698 | _('command request missing "name" field')) |
|
699 | 699 | |
|
700 | 700 | if b'args' not in request: |
|
701 | 701 | request[b'args'] = {} |
|
702 | 702 | |
|
703 | 703 | assert requestid not in self._activecommands |
|
704 | 704 | self._activecommands.add(requestid) |
|
705 | 705 | |
|
706 | 706 | return 'runcommand', { |
|
707 | 707 | 'requestid': requestid, |
|
708 | 708 | 'command': request[b'name'], |
|
709 | 709 | 'args': request[b'args'], |
|
710 | 710 | 'data': entry['data'].getvalue() if entry['data'] else None, |
|
711 | 711 | } |
|
712 | 712 | |
|
713 | 713 | def _makewantframeresult(self): |
|
714 | 714 | return 'wantframe', { |
|
715 | 715 | 'state': self._state, |
|
716 | 716 | } |
|
717 | 717 | |
|
718 | 718 | def _validatecommandrequestframe(self, frame): |
|
719 | 719 | new = frame.flags & FLAG_COMMAND_REQUEST_NEW |
|
720 | 720 | continuation = frame.flags & FLAG_COMMAND_REQUEST_CONTINUATION |
|
721 | 721 | |
|
722 | 722 | if new and continuation: |
|
723 | 723 | self._state = 'errored' |
|
724 | 724 | return self._makeerrorresult( |
|
725 | 725 | _('received command request frame with both new and ' |
|
726 | 726 | 'continuation flags set')) |
|
727 | 727 | |
|
728 | 728 | if not new and not continuation: |
|
729 | 729 | self._state = 'errored' |
|
730 | 730 | return self._makeerrorresult( |
|
731 | 731 | _('received command request frame with neither new nor ' |
|
732 | 732 | 'continuation flags set')) |
|
733 | 733 | |
|
734 | 734 | def _onframeidle(self, frame): |
|
735 | 735 | # The only frame type that should be received in this state is a |
|
736 | 736 | # command request. |
|
737 | 737 | if frame.typeid != FRAME_TYPE_COMMAND_REQUEST: |
|
738 | 738 | self._state = 'errored' |
|
739 | 739 | return self._makeerrorresult( |
|
740 | 740 | _('expected command request frame; got %d') % frame.typeid) |
|
741 | 741 | |
|
742 | 742 | res = self._validatecommandrequestframe(frame) |
|
743 | 743 | if res: |
|
744 | 744 | return res |
|
745 | 745 | |
|
746 | 746 | if frame.requestid in self._receivingcommands: |
|
747 | 747 | self._state = 'errored' |
|
748 | 748 | return self._makeerrorresult( |
|
749 | 749 | _('request with ID %d already received') % frame.requestid) |
|
750 | 750 | |
|
751 | 751 | if frame.requestid in self._activecommands: |
|
752 | 752 | self._state = 'errored' |
|
753 | 753 | return self._makeerrorresult( |
|
754 | 754 | _('request with ID %d is already active') % frame.requestid) |
|
755 | 755 | |
|
756 | 756 | new = frame.flags & FLAG_COMMAND_REQUEST_NEW |
|
757 | 757 | moreframes = frame.flags & FLAG_COMMAND_REQUEST_MORE_FRAMES |
|
758 | 758 | expectingdata = frame.flags & FLAG_COMMAND_REQUEST_EXPECT_DATA |
|
759 | 759 | |
|
760 | 760 | if not new: |
|
761 | 761 | self._state = 'errored' |
|
762 | 762 | return self._makeerrorresult( |
|
763 | 763 | _('received command request frame without new flag set')) |
|
764 | 764 | |
|
765 | 765 | payload = util.bytesio() |
|
766 | 766 | payload.write(frame.payload) |
|
767 | 767 | |
|
768 | 768 | self._receivingcommands[frame.requestid] = { |
|
769 | 769 | 'payload': payload, |
|
770 | 770 | 'data': None, |
|
771 | 771 | 'requestdone': not moreframes, |
|
772 | 772 | 'expectingdata': bool(expectingdata), |
|
773 | 773 | } |
|
774 | 774 | |
|
775 | 775 | # This is the final frame for this request. Dispatch it. |
|
776 | 776 | if not moreframes and not expectingdata: |
|
777 | 777 | return self._makeruncommandresult(frame.requestid) |
|
778 | 778 | |
|
779 | 779 | assert moreframes or expectingdata |
|
780 | 780 | self._state = 'command-receiving' |
|
781 | 781 | return self._makewantframeresult() |
|
782 | 782 | |
|
783 | 783 | def _onframecommandreceiving(self, frame): |
|
784 | 784 | if frame.typeid == FRAME_TYPE_COMMAND_REQUEST: |
|
785 | 785 | # Process new command requests as such. |
|
786 | 786 | if frame.flags & FLAG_COMMAND_REQUEST_NEW: |
|
787 | 787 | return self._onframeidle(frame) |
|
788 | 788 | |
|
789 | 789 | res = self._validatecommandrequestframe(frame) |
|
790 | 790 | if res: |
|
791 | 791 | return res |
|
792 | 792 | |
|
793 | 793 | # All other frames should be related to a command that is currently |
|
794 | 794 | # receiving but is not active. |
|
795 | 795 | if frame.requestid in self._activecommands: |
|
796 | 796 | self._state = 'errored' |
|
797 | 797 | return self._makeerrorresult( |
|
798 | 798 | _('received frame for request that is still active: %d') % |
|
799 | 799 | frame.requestid) |
|
800 | 800 | |
|
801 | 801 | if frame.requestid not in self._receivingcommands: |
|
802 | 802 | self._state = 'errored' |
|
803 | 803 | return self._makeerrorresult( |
|
804 | 804 | _('received frame for request that is not receiving: %d') % |
|
805 | 805 | frame.requestid) |
|
806 | 806 | |
|
807 | 807 | entry = self._receivingcommands[frame.requestid] |
|
808 | 808 | |
|
809 | 809 | if frame.typeid == FRAME_TYPE_COMMAND_REQUEST: |
|
810 | 810 | moreframes = frame.flags & FLAG_COMMAND_REQUEST_MORE_FRAMES |
|
811 | 811 | expectingdata = bool(frame.flags & FLAG_COMMAND_REQUEST_EXPECT_DATA) |
|
812 | 812 | |
|
813 | 813 | if entry['requestdone']: |
|
814 | 814 | self._state = 'errored' |
|
815 | 815 | return self._makeerrorresult( |
|
816 | 816 | _('received command request frame when request frames ' |
|
817 | 817 | 'were supposedly done')) |
|
818 | 818 | |
|
819 | 819 | if expectingdata != entry['expectingdata']: |
|
820 | 820 | self._state = 'errored' |
|
821 | 821 | return self._makeerrorresult( |
|
822 | 822 | _('mismatch between expect data flag and previous frame')) |
|
823 | 823 | |
|
824 | 824 | entry['payload'].write(frame.payload) |
|
825 | 825 | |
|
826 | 826 | if not moreframes: |
|
827 | 827 | entry['requestdone'] = True |
|
828 | 828 | |
|
829 | 829 | if not moreframes and not expectingdata: |
|
830 | 830 | return self._makeruncommandresult(frame.requestid) |
|
831 | 831 | |
|
832 | 832 | return self._makewantframeresult() |
|
833 | 833 | |
|
834 | 834 | elif frame.typeid == FRAME_TYPE_COMMAND_DATA: |
|
835 | 835 | if not entry['expectingdata']: |
|
836 | 836 | self._state = 'errored' |
|
837 | 837 | return self._makeerrorresult(_( |
|
838 | 838 | 'received command data frame for request that is not ' |
|
839 | 839 | 'expecting data: %d') % frame.requestid) |
|
840 | 840 | |
|
841 | 841 | if entry['data'] is None: |
|
842 | 842 | entry['data'] = util.bytesio() |
|
843 | 843 | |
|
844 | 844 | return self._handlecommanddataframe(frame, entry) |
|
845 | 845 | else: |
|
846 | 846 | self._state = 'errored' |
|
847 | 847 | return self._makeerrorresult(_( |
|
848 | 848 | 'received unexpected frame type: %d') % frame.typeid) |
|
849 | 849 | |
|
850 | 850 | def _handlecommanddataframe(self, frame, entry): |
|
851 | 851 | assert frame.typeid == FRAME_TYPE_COMMAND_DATA |
|
852 | 852 | |
|
853 | 853 | # TODO support streaming data instead of buffering it. |
|
854 | 854 | entry['data'].write(frame.payload) |
|
855 | 855 | |
|
856 | 856 | if frame.flags & FLAG_COMMAND_DATA_CONTINUATION: |
|
857 | 857 | return self._makewantframeresult() |
|
858 | 858 | elif frame.flags & FLAG_COMMAND_DATA_EOS: |
|
859 | 859 | entry['data'].seek(0) |
|
860 | 860 | return self._makeruncommandresult(frame.requestid) |
|
861 | 861 | else: |
|
862 | 862 | self._state = 'errored' |
|
863 | 863 | return self._makeerrorresult(_('command data frame without ' |
|
864 | 864 | 'flags')) |
|
865 | 865 | |
|
866 | 866 | def _onframeerrored(self, frame): |
|
867 | 867 | return self._makeerrorresult(_('server already errored')) |
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