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add struct ConnectTokenClient and try_read method for it (#30)
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* check size of connect token packet on client side

* no need to make a copy of packet data

* add struct ConnectTokenClient

* fix bug in try_read for ConnectTokenClient

* add get_serialized_data method for ConnectTokenClient and check for padding when reading
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@Sid-Bhatia-0
Sid-Bhatia-0 authored Mar 16, 2024
1 parent d03cb20 commit ea765e3
Showing 1 changed file with 117 additions and 81 deletions.
198 changes: 117 additions & 81 deletions netcode/simulate.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -156,6 +156,19 @@ struct EncryptedPrivateConnectToken
connect_token::ConnectToken
end

struct ConnectTokenClient
netcode_version_info::Vector{UInt8}
protocol_id::TYPE_OF_PROTOCOL_ID
create_timestamp::TYPE_OF_TIMESTAMP
expire_timestamp::TYPE_OF_TIMESTAMP
nonce::Vector{UInt8}
encrypted_private_connect_token_data::Vector{UInt8}
timeout_seconds::TYPE_OF_TIMEOUT_SECONDS
netcode_addresses::Vector{NetcodeInetAddr}
client_to_server_key::Vector{UInt8}
server_to_client_key::Vector{UInt8}
end

function ConnectToken(client_id)
create_timestamp = time_ns()
expire_timestamp = create_timestamp + CONNECT_TOKEN_EXPIRE_SECONDS * 10 ^ 9
Expand Down Expand Up @@ -251,6 +264,34 @@ function get_serialized_size(connect_token::ConnectToken)
return n
end

function get_serialized_size(connect_token_client::ConnectTokenClient)
n = 0

n += get_serialized_size(connect_token_client.netcode_version_info)

n += get_serialized_size(connect_token_client.protocol_id)

n += get_serialized_size(connect_token_client.create_timestamp)

n += get_serialized_size(connect_token_client.expire_timestamp)

n += get_serialized_size(connect_token_client.nonce)

n += get_serialized_size(connect_token_client.encrypted_private_connect_token_data)

n += get_serialized_size(connect_token_client.timeout_seconds)

n += get_serialized_size(zero(TYPE_OF_NUM_SERVER_ADDRESSES))

n += sum(get_serialized_size, connect_token_client.netcode_addresses)

n += get_serialized_size(connect_token_client.client_to_server_key)

n += get_serialized_size(connect_token_client.server_to_client_key)

return n
end

get_address_type(::Sockets.InetAddr{Sockets.IPv4}) = ADDRESS_TYPE_IPV4
get_address_type(::Sockets.InetAddr{Sockets.IPv6}) = ADDRESS_TYPE_IPV6
get_address_type(netcode_inetaddr::NetcodeInetAddr) = get_address_type(netcode_inetaddr.address)
Expand Down Expand Up @@ -411,6 +452,78 @@ function Base.write(io::IO, padded_connect_token::PaddedConnectToken)
return n
end

function try_read(data::Vector{UInt8}, ::Type{ConnectTokenClient})
if length(data) != SIZE_OF_PADDED_CONNECT_TOKEN
return nothing
end

io = IOBuffer(data)

netcode_version_info = read(io, SIZE_OF_NETCODE_VERSION_INFO)
if netcode_version_info != NETCODE_VERSION_INFO
return nothing
end

protocol_id = read(io, TYPE_OF_PROTOCOL_ID)
if protocol_id != PROTOCOL_ID
return nothing
end

create_timestamp = read(io, TYPE_OF_TIMESTAMP)
expire_timestamp = read(io, TYPE_OF_TIMESTAMP)
if expire_timestamp < create_timestamp
return nothing
end

nonce = read(io, SIZE_OF_NONCE)

encrypted_private_connect_token_data = read(io, SIZE_OF_ENCRYPTED_PRIVATE_CONNECT_TOKEN_DATA)

timeout_seconds = read(io, TYPE_OF_TIMEOUT_SECONDS)

num_server_addresses = read(io, TYPE_OF_NUM_SERVER_ADDRESSES)
if !(1 <= num_server_addresses <= MAX_GAME_SERVERS)
return nothing
end

netcode_addresses = NetcodeInetAddr[]

for i in 1:num_server_addresses
netcode_address = try_read(io, NetcodeInetAddr)
if !isnothing(netcode_address)
push!(netcode_addresses, netcode_address)
else
return nothing
end
end

client_to_server_key = read(io, SIZE_OF_CLIENT_TO_SERVER_KEY)

server_to_client_key = read(io, SIZE_OF_SERVER_TO_CLIENT_KEY)

connect_token_client = ConnectTokenClient(
netcode_version_info,
protocol_id,
create_timestamp,
expire_timestamp,
nonce,
encrypted_private_connect_token_data,
timeout_seconds,
netcode_addresses,
client_to_server_key,
server_to_client_key,
)

size_of_connect_token_client = get_serialized_size(connect_token_client)

padding = read(io)
if length(padding) != (SIZE_OF_PADDED_CONNECT_TOKEN - size_of_connect_token_client) || any(!=(0), padding)
return nothing
end

return connect_token_client
end

function get_time(reference_time)
# get time (in units of nanoseconds) since reference_time
# places an upper bound on how much time can the program be running until time wraps around giving meaningless values
Expand Down Expand Up @@ -484,89 +597,12 @@ function start_client(auth_server_address, username, password)

response = HTTP.get("http://" * username * ":" * hashed_password * "@" * string(auth_server_address.host) * ":" * string(auth_server_address.port))

io_connect_token = IOBuffer(copy(response.body))

netcode_version_info = read(io_connect_token, SIZE_OF_NETCODE_VERSION_INFO)

protocol_id = read(io_connect_token, TYPE_OF_PROTOCOL_ID)

create_timestamp = read(io_connect_token, TYPE_OF_TIMESTAMP)

expire_timestamp = read(io_connect_token, TYPE_OF_TIMESTAMP)

nonce = read(io_connect_token, SIZE_OF_NONCE)

encrypted_private_connect_token_data = read(io_connect_token, SIZE_OF_ENCRYPTED_PRIVATE_CONNECT_TOKEN_DATA)

timeout_seconds = read(io_connect_token, TYPE_OF_TIMEOUT_SECONDS)

num_server_addresses = read(io_connect_token, TYPE_OF_NUM_SERVER_ADDRESSES)

netcode_addresses = NetcodeInetAddr[]

for i in 1:num_server_addresses
netcode_address = try_read(io_connect_token, NetcodeInetAddr)
if !isnothing(netcode_address)
push!(netcode_addresses, netcode_address)
else
error("Unable to read a value of type NetcodeInetAddr")
end
end

client_to_server_key = read(io_connect_token, SIZE_OF_CLIENT_TO_SERVER_KEY)

server_to_client_key = read(io_connect_token, SIZE_OF_SERVER_TO_CLIENT_KEY)

@info "connect_token client readable data" io_connect_token.size netcode_version_info protocol_id create_timestamp expire_timestamp nonce timeout_seconds num_server_addresses netcode_addresses client_to_server_key server_to_client_key

let
# client doesn't have access to SERVER_SIDE_SHARED_KEY so it cannot decrypt the encrypted_private_connect_token_data. But I am still accessing the global variable SERVER_SIDE_SHARED_KEY and decrypting it for testing purposes

decrypted = zeros(UInt8, SIZE_OF_ENCRYPTED_PRIVATE_CONNECT_TOKEN_DATA - SIZE_OF_HMAC)
decrypted_length_ref = Ref{UInt}()

ciphertext = encrypted_private_connect_token_data

io_associated_data = IOBuffer(maxsize = SIZE_OF_NETCODE_VERSION_INFO + SIZE_OF_PROTOCOL_ID + SIZE_OF_TIMESTAMP)

write(io_associated_data, NETCODE_VERSION_INFO)

write(io_associated_data, protocol_id)

write(io_associated_data, expire_timestamp)

decrypt_status = Sodium.LibSodium.crypto_aead_xchacha20poly1305_ietf_decrypt(decrypted, decrypted_length_ref, C_NULL, ciphertext, length(ciphertext), io_associated_data.data, io_associated_data.size, nonce, SERVER_SIDE_SHARED_KEY)
@assert decrypt_status == 0

io_decrypted = IOBuffer(decrypted)

client_id = read(io_decrypted, TYPE_OF_CLIENT_ID)

timeout_seconds = read(io_decrypted, TYPE_OF_TIMEOUT_SECONDS)

num_server_addresses = read(io_decrypted, TYPE_OF_NUM_SERVER_ADDRESSES)

netcode_addresses = NetcodeInetAddr[]

for i in 1:num_server_addresses
netcode_address = try_read(io_decrypted, NetcodeInetAddr)
if !isnothing(netcode_address)
push!(netcode_addresses, netcode_address)
else
error("Unable to read a value of type NetcodeInetAddr")
end
end

client_to_server_key = read(io_decrypted, SIZE_OF_CLIENT_TO_SERVER_KEY)

server_to_client_key = read(io_decrypted, SIZE_OF_SERVER_TO_CLIENT_KEY)

user_data = read(io_decrypted, SIZE_OF_USER_DATA)

@info "connect_token client un-readable data (for testing)" decrypt_status client_id timeout_seconds num_server_addresses netcode_addresses client_to_server_key server_to_client_key user_data
connect_token_client = try_read(copy(response.body), ConnectTokenClient)
if isnothing(connect_token_client)
error("Invalid connect token packet received")
end

game_server_address = first(netcode_addresses).address
game_server_address = first(connect_token_client.netcode_addresses).address

@info "Client obtained game_server_address" game_server_address

Expand Down

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