121 lines
2.9 KiB
Nim
121 lines
2.9 KiB
Nim
## nim-ws
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## Copyright (c) 2021 Status Research & Development GmbH
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## Licensed under either of
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## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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## * MIT license ([LICENSE-MIT](LICENSE-MIT))
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## at your option.
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## This file may not be copied, modified, or distributed except according to
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## those terms.
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import
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std/[strutils],
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pkg/[stew/results,
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stew/base64,
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chronos,
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chronicles],
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../../ws/types,
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../../ws/frame
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type
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Base64Ext = ref object of Ext
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padding: bool
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transform: bool
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const
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extID = "base64"
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method decode(ext: Base64Ext, frame: Frame): Future[Frame] {.async.} =
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if frame.opcode notin {Opcode.Text, Opcode.Binary, Opcode.Cont}:
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return frame
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if frame.opcode in {Opcode.Text, Opcode.Binary}:
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ext.transform = frame.rsv2
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frame.rsv2 = false
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if not ext.transform:
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return frame
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if frame.length > 0:
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var data: seq[byte]
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var buf: array[0xFFFF, byte]
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while data.len < frame.length.int:
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let len = min(frame.length.int - data.len, buf.len)
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let read = await frame.read(ext.session.stream.reader, addr buf[0], len)
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data.add toOpenArray(buf, 0, read - 1)
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if data.len > ext.session.frameSize:
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raise newException(WSPayloadTooLarge, "payload exceeds allowed max frame size")
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# bug in Base64.Decode when accepts seq[byte]
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let instr = cast[string](data)
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if ext.padding:
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frame.data = Base64Pad.decode(instr)
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else:
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frame.data = Base64.decode(instr)
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trace "Base64Ext decode", input=frame.length, output=frame.data.len
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frame.length = frame.data.len.uint64
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frame.offset = 0
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frame.consumed = 0
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frame.mask = false
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return frame
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method encode(ext: Base64Ext, frame: Frame): Future[Frame] {.async.} =
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if frame.opcode notin {Opcode.Text, Opcode.Binary, Opcode.Cont}:
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return frame
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if frame.opcode in {Opcode.Text, Opcode.Binary}:
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ext.transform = true
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frame.rsv2 = ext.transform
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if not ext.transform:
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return frame
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frame.length = frame.data.len.uint64
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if ext.padding:
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frame.data = cast[seq[byte]](Base64Pad.encode(frame.data))
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else:
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frame.data = cast[seq[byte]](Base64.encode(frame.data))
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trace "Base64Ext encode", input=frame.length, output=frame.data.len
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frame.length = frame.data.len.uint64
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frame.offset = 0
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frame.consumed = 0
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return frame
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method toHttpOptions(ext: Base64Ext): string =
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extID & "; pad=" & $ext.padding
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proc base64Factory*(padding: bool): ExtFactory =
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proc factory(isServer: bool,
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args: seq[ExtParam]): Result[Ext, string] {.
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gcsafe, raises: [Defect].} =
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# you can capture configuration variables via closure
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# if you want
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var ext = Base64Ext(
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name : extID,
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transform: false
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)
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for arg in args:
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if arg.name == "pad":
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ext.padding = arg.value == "true"
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break
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ok(ext)
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ExtFactory(
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name: extID,
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factory: factory,
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clientOffer: extID & "; pad=" & $padding
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)
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