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nim-webrtc
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Ludovic Chenut 2024-02-29 15:15:55 +01:00
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28
README.md Normal file
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@ -0,0 +1,28 @@
# Nim-Webrtc
![Stability: experimental](https://img.shields.io/badge/stability-experimental-orange.svg)
[![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
[![License: Apache](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
A simple WebRTC stack first implemented for [libp2p WebRTC direct transport](https://github.com/libp2p/specs/blob/master/webrtc/webrtc-direct.md).
It uses a wrapper from two different C libraries:
- [usrsctp]() for the SCTP stack
- [mbedtls]() for the DTLS stack
## Usage
## Installation
## TODO
## License
Licensed and distributed under either of
* MIT license: [LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT
or
* Apache License, Version 2.0, ([LICENSE-APACHEv2](LICENSE-APACHEv2) or http://www.apache.org/licenses/LICENSE-2.0)
at your option. This file may not be copied, modified, or distributed except according to those terms.

76
webrtc/stun/stun_attributes.nim
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@ -7,14 +7,61 @@
# This file may not be copied, modified, or distributed except according to
# those terms.
import sequtils, typetraits
import std/sha1, sequtils, typetraits, std/md5
import binary_serialization,
stew/byteutils,
chronos
import ../utils
type
StunAttributeEncodingError* = object of CatchableError
# -- Utils --
proc createCrc32Table(): array[0..255, uint32] =
for i in 0..255:
var rem = i.uint32
for j in 0..7:
if (rem and 1) > 0:
rem = (rem shr 1) xor 0xedb88320'u32
else:
rem = rem shr 1
result[i] = rem
proc crc32(s: seq[byte]): uint32 =
# CRC-32 is used for the fingerprint attribute
# See https://datatracker.ietf.org/doc/html/rfc5389#section-15.5
const crc32table = createCrc32Table()
result = 0xffffffff'u32
for c in s:
result = (result shr 8) xor crc32table[(result and 0xff) xor c]
result = not result
proc hmacSha1(key: seq[byte], msg: seq[byte]): seq[byte] =
# HMAC-SHA1 is used for the message integrity attribute
# See https://datatracker.ietf.org/doc/html/rfc5389#section-15.4
let
keyPadded =
if len(key) > 64:
@(secureHash(key.mapIt(it.chr)).distinctBase)
elif key.len() < 64:
key.concat(newSeq[byte](64 - key.len()))
else:
key
innerHash = keyPadded.
mapIt(it xor 0x36'u8).
concat(msg).
mapIt(it.chr).
secureHash()
outerHash = keyPadded.
mapIt(it xor 0x5c'u8).
concat(@(innerHash.distinctBase)).
mapIt(it.chr).
secureHash()
return @(outerHash.distinctBase)
# -- Attributes --
# There are obviously some attributes implementation that are missing,
# it might be something to do eventually if we want to make this
# repository work for other project than nim-libp2p
#
# Stun Attribute
# 0 1 2 3
# 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
@ -23,6 +70,10 @@ type
# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
# | Value (variable) ....
# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
type
StunAttributeEncodingError* = object of CatchableError
RawStunAttribute* = object
attributeType*: uint16
length* {.bin_value: it.value.len.}: uint16
@ -74,6 +125,8 @@ proc isRequired*(typ: uint16): bool = typ <= 0x7FFF'u16
proc isOptional*(typ: uint16): bool = typ >= 0x8000'u16
# Error Code
# https://datatracker.ietf.org/doc/html/rfc5389#section-15.6
type
ErrorCodeEnum* = enum
ECTryAlternate = 300
@ -100,6 +153,8 @@ proc encode*(T: typedesc[ErrorCode], code: ErrorCodeEnum, reason: string = ""):
value: value)
# Unknown Attribute
# https://datatracker.ietf.org/doc/html/rfc5389#section-15.9
type
UnknownAttribute* = object
unknownAttr: seq[uint16]
@ -113,6 +168,7 @@ proc encode*(T: typedesc[UnknownAttribute], unknownAttr: seq[uint16]): RawStunAt
value: value)
# Fingerprint
# https://datatracker.ietf.org/doc/html/rfc5389#section-15.5
type
Fingerprint* = object
@ -125,6 +181,7 @@ proc encode*(T: typedesc[Fingerprint], msg: seq[byte]): RawStunAttribute =
value: value)
# Xor Mapped Address
# https://datatracker.ietf.org/doc/html/rfc5389#section-15.2
type
MappedAddressFamily {.size: 1.} = enum
@ -141,26 +198,26 @@ proc encode*(T: typedesc[XorMappedAddress], ta: TransportAddress,
tid: array[12, byte]): RawStunAttribute =
const magicCookie = @[ 0x21'u8, 0x12, 0xa4, 0x42 ]
let
address =
(address, family) =
if ta.family == AddressFamily.IPv4:
var s = newSeq[uint8](4)
for i in 0..3:
s[i] = ta.address_v4[i] xor magicCookie[i]
s
(s, MAFIPv4)
else:
let magicCookieTid = magicCookie.concat(@tid)
var s = newSeq[uint8](16)
for i in 0..15:
s[i] = ta.address_v6[i] xor magicCookieTid[i]
s
xma = T(family: if ta.family == AddressFamily.IPv4: MAFIPv4 else: MAFIPv6,
port: ta.port.distinctBase xor 0x2112'u16, address: address)
(s, MAFIPv6)
xma = T(family: family, port: ta.port.distinctBase xor 0x2112'u16, address: address)
value = Binary.encode(xma)
result = RawStunAttribute(attributeType: AttrXORMappedAddress.uint16,
length: value.len().uint16,
value: value)
# Message Integrity
# https://datatracker.ietf.org/doc/html/rfc5389#section-15.4
type
MessageIntegrity* = object
@ -169,5 +226,4 @@ type
proc encode*(T: typedesc[MessageIntegrity], msg: seq[byte], key: seq[byte]): RawStunAttribute =
let value = Binary.encode(T(msgInt: hmacSha1(key, msg)))
result = RawStunAttribute(attributeType: AttrMessageIntegrity.uint16,
length: value.len().uint16,
value: value)
length: value.len().uint16, value: value)

1
webrtc/stun/stun_connection.nim
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@ -21,7 +21,6 @@ proc handles(self: StunConn) {.async.} =
while true: # TODO: while not self.conn.atEof()
let (msg, raddr) = await self.conn.read()
if Stun.isMessage(msg):
echo "\e[35;1m<STUN>\e[0m"
let res = Stun.getResponse(msg, self.laddr)
if res.isSome():
await self.conn.write(raddr, res.get())

46
webrtc/utils.nim
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@ -1,46 +0,0 @@
# Nim-WebRTC
# Copyright (c) 2023 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
# * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.
import std/sha1, sequtils, typetraits, std/md5
proc createCrc32Table(): array[0..255, uint32] =
for i in 0..255:
var rem = i.uint32
for j in 0..7:
if (rem and 1) > 0: rem = (rem shr 1) xor 0xedb88320'u32
else: rem = rem shr 1
result[i] = rem
proc crc32*(s: seq[byte]): uint32 =
const crc32table = createCrc32Table()
result = 0xffffffff'u32
for c in s:
result = (result shr 8) xor crc32table[(result and 0xff) xor c]
result = not result
proc hmacSha1*(key: seq[byte], msg: seq[byte]): seq[byte] =
let
keyPadded =
if len(key) > 64:
@(secureHash(key.mapIt(it.chr)).distinctBase)
elif key.len() < 64:
key.concat(newSeq[byte](64 - key.len()))
else:
key
innerHash = keyPadded.
mapIt(it xor 0x36'u8).
concat(msg).
mapIt(it.chr).
secureHash()
outerHash = keyPadded.
mapIt(it xor 0x5c'u8).
concat(@(innerHash.distinctBase)).
mapIt(it.chr).
secureHash()
return @(outerHash.distinctBase)