refactor: extract protocol/ — split CoAP wire helpers from DtlsCoapSession
This commit is contained in:
Marc Billow
@@ -0,0 +1,139 @@
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"""CoAP wire encoding/decoding (RFC 7252 + 7641 + 7959).
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Pure functions — no sockets, no DTLS. Split out of the original
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coap_dtls.py so protocol/dtls_session.py (the stateful session) and
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this module (stateless wire format) can be reasoned about and tested
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independently.
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"""
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import struct
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# CoAP option numbers (RFC 7252 + 7641 + 7959)
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URI_PATH = 11
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URI_QUERY = 15
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OBSERVE = 6
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CONTENT_FORMAT = 12
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ACCEPT = 17
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BLOCK2 = 23
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SIZE2 = 28
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# CoAP message types
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TYPE_CON = 0
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TYPE_NON = 1
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TYPE_ACK = 2
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TYPE_RST = 3
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# CoAP method codes
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METHOD_GET = 0x01
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METHOD_POST = 0x02
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# CoAP content-format value for application/cbor
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CF_CBOR = b'\x3c'
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# OBSERVE option values (RFC 7641 §2)
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OBSERVE_REGISTER = b'' # register / refresh
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OBSERVE_DEREGISTER = bytes([1]) # deregister
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# Block2 SZX=6 → 1024-byte blocks. The largest size Samsung's RT-OCF
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# will honour and the only one the probes have validated end-to-end.
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BLOCK_SZX = 6
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def _vlen(v):
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"""Variable-length integer encoder used in option deltas + lengths."""
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if v < 13: return v, b''
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if v < 269: return 13, bytes([v - 13])
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return 14, struct.pack('>H', v - 269)
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def encode_options(opts):
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"""Encode a list of (option_number, value_bytes) tuples."""
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out = b''
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prev = 0
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for n, val in sorted(opts, key=lambda x: x[0]):
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d, dx = _vlen(n - prev)
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l, lx = _vlen(len(val))
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out += bytes([(d << 4) | l]) + dx + lx + val
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prev = n
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return out
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def parse_coap(data):
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"""Decode a CoAP datagram. Returns (mtype, code, mid, token,
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options, payload). options is a list of (num, value_bytes)."""
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mt = (data[0] >> 4) & 0x03
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tkl = data[0] & 0x0F
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code = data[1]
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mid = int.from_bytes(data[2:4], 'big')
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tok = data[4:4 + tkl]
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i = 4 + tkl
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opts = []
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prev = 0
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payload = b''
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while i < len(data):
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b = data[i]
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if b == 0xFF:
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payload = data[i + 1:]
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break
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d_nib, l_nib = b >> 4, b & 0x0F
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i += 1
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if d_nib == 13:
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delta = 13 + data[i]; i += 1
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elif d_nib == 14:
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delta = 269 + int.from_bytes(data[i:i + 2], 'big'); i += 2
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elif d_nib == 15:
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raise ValueError("reserved option delta nibble 15")
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else:
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delta = d_nib
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if l_nib == 13:
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length = 13 + data[i]; i += 1
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elif l_nib == 14:
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length = 269 + int.from_bytes(data[i:i + 2], 'big'); i += 2
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elif l_nib == 15:
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raise ValueError("reserved option length nibble 15")
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else:
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length = l_nib
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num = prev + delta
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opts.append((num, data[i:i + length]))
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i += length
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prev = num
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return mt, code, mid, tok, opts, payload
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def build_coap(mtype, code, mid, token, options, payload=b''):
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"""Build a CoAP datagram. mtype: CON/NON/ACK/RST. token: bytes (may
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be empty for ACK). options: list of (num, value_bytes)."""
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tkl = len(token)
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hdr = bytes([(1 << 6) | (mtype << 4) | tkl, code,
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(mid >> 8) & 0xFF, mid & 0xFF])
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body = hdr + token + encode_options(options)
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if payload:
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body += b'\xFF' + payload
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return body
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def block_value(num, more, szx):
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"""Encode a CoAP Block-N option value."""
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v = (num << 4) | ((more & 1) << 3) | (szx & 7)
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if v <= 0xFF: return bytes([v])
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if v <= 0xFFFF: return struct.pack('>H', v)
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return struct.pack('>I', v)[1:]
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def fmt_code(c):
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"""0x45 → '2.05', 0x84 → '4.04'. Used in log lines."""
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return f"{c >> 5}.{c & 0x1F:02d}"
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def split_dtls(buf):
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"""Split a UDP datagram that contains one-or-more DTLS records.
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OpenSSL sometimes hands the BIO multiple records back-to-back; we
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must send each as its own UDP datagram or TizenRT drops them."""
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o, out = 0, []
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while o + 13 <= len(buf):
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L = int.from_bytes(buf[o + 11:o + 13], 'big')
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end = o + 13 + L
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if end > len(buf):
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break
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out.append(buf[o:end])
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o = end
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return out
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@@ -20,13 +20,20 @@ delivered via the on_notification callback.
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"""
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import os
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import socket
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import struct
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import threading
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import time
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from OpenSSL import SSL
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from .logger import logger
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from .coap import (
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URI_PATH, URI_QUERY, OBSERVE, CONTENT_FORMAT, ACCEPT, BLOCK2, SIZE2,
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TYPE_CON, TYPE_NON, TYPE_ACK, TYPE_RST,
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METHOD_GET, METHOD_POST, CF_CBOR,
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OBSERVE_REGISTER, OBSERVE_DEREGISTER, BLOCK_SZX,
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encode_options, parse_coap, build_coap, block_value, fmt_code,
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split_dtls as _split_dtls,
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)
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from samsung_appliance.logger import logger
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# Diagnostic logging — when DEBUG_BRIDGE=1 in env, the bridge dumps
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@@ -37,138 +44,6 @@ from .logger import logger
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DEBUG_BRIDGE = os.environ.get('DEBUG_BRIDGE') == '1'
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# CoAP option numbers (RFC 7252 + 7641 + 7959)
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URI_PATH = 11
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URI_QUERY = 15
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OBSERVE = 6
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CONTENT_FORMAT = 12
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ACCEPT = 17
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BLOCK2 = 23
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SIZE2 = 28
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# CoAP message types
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TYPE_CON = 0
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TYPE_NON = 1
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TYPE_ACK = 2
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TYPE_RST = 3
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# CoAP method codes
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METHOD_GET = 0x01
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METHOD_POST = 0x02
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# CoAP content-format value for application/cbor
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CF_CBOR = b'\x3c'
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# OBSERVE option values (RFC 7641 §2)
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OBSERVE_REGISTER = b'' # register / refresh
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OBSERVE_DEREGISTER = bytes([1]) # deregister
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# Block2 SZX=6 → 1024-byte blocks. The largest size Samsung's RT-OCF
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# will honour and the only one the probes have validated end-to-end.
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BLOCK_SZX = 6
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def _vlen(v):
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"""Variable-length integer encoder used in option deltas + lengths."""
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if v < 13: return v, b''
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if v < 269: return 13, bytes([v - 13])
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return 14, struct.pack('>H', v - 269)
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def encode_options(opts):
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"""Encode a list of (option_number, value_bytes) tuples."""
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out = b''
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prev = 0
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for n, val in sorted(opts, key=lambda x: x[0]):
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d, dx = _vlen(n - prev)
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l, lx = _vlen(len(val))
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out += bytes([(d << 4) | l]) + dx + lx + val
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prev = n
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return out
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def parse_coap(data):
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"""Decode a CoAP datagram. Returns (mtype, code, mid, token,
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options, payload). options is a list of (num, value_bytes)."""
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mt = (data[0] >> 4) & 0x03
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tkl = data[0] & 0x0F
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code = data[1]
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mid = int.from_bytes(data[2:4], 'big')
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tok = data[4:4 + tkl]
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i = 4 + tkl
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opts = []
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prev = 0
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payload = b''
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while i < len(data):
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b = data[i]
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if b == 0xFF:
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payload = data[i + 1:]
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break
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d_nib, l_nib = b >> 4, b & 0x0F
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i += 1
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if d_nib == 13:
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delta = 13 + data[i]; i += 1
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elif d_nib == 14:
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delta = 269 + int.from_bytes(data[i:i + 2], 'big'); i += 2
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elif d_nib == 15:
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raise ValueError("reserved option delta nibble 15")
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else:
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delta = d_nib
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if l_nib == 13:
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length = 13 + data[i]; i += 1
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elif l_nib == 14:
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length = 269 + int.from_bytes(data[i:i + 2], 'big'); i += 2
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elif l_nib == 15:
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raise ValueError("reserved option length nibble 15")
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else:
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length = l_nib
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num = prev + delta
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opts.append((num, data[i:i + length]))
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i += length
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prev = num
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return mt, code, mid, tok, opts, payload
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def build_coap(mtype, code, mid, token, options, payload=b''):
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"""Build a CoAP datagram. mtype: CON/NON/ACK/RST. token: bytes (may
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be empty for ACK). options: list of (num, value_bytes)."""
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tkl = len(token)
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hdr = bytes([(1 << 6) | (mtype << 4) | tkl, code,
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(mid >> 8) & 0xFF, mid & 0xFF])
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body = hdr + token + encode_options(options)
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if payload:
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body += b'\xFF' + payload
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return body
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def block_value(num, more, szx):
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"""Encode a CoAP Block-N option value."""
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v = (num << 4) | ((more & 1) << 3) | (szx & 7)
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if v <= 0xFF: return bytes([v])
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if v <= 0xFFFF: return struct.pack('>H', v)
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return struct.pack('>I', v)[1:]
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def fmt_code(c):
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"""0x45 → '2.05', 0x84 → '4.04'. Used in log lines."""
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return f"{c >> 5}.{c & 0x1F:02d}"
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def _split_dtls(buf):
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"""Split a UDP datagram that contains one-or-more DTLS records.
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OpenSSL sometimes hands the BIO multiple records back-to-back; we
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must send each as its own UDP datagram or TizenRT drops them."""
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o, out = 0, []
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while o + 13 <= len(buf):
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L = int.from_bytes(buf[o + 11:o + 13], 'big')
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end = o + 13 + L
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if end > len(buf):
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break
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out.append(buf[o:end])
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o = end
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return out
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class DtlsCoapSession:
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"""Single sustained DTLS-CoAP session.
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@@ -1,4 +1,4 @@
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from samsung_appliance.coap_dtls import (
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from protocol.coap import (
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build_coap, parse_coap, encode_options, block_value, fmt_code,
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TYPE_CON, METHOD_GET, URI_PATH, ACCEPT, CF_CBOR, BLOCK2,
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)
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