lib/socket: intro `UDPSocket` and its services

[nit.git] / lib / socket / socket.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2013 Matthieu Lucas <lucasmatthieu@gmail.com>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Socket services
module socket

private import socket_c
intrude import standard::stream

# A general Socket, either TCP or UDP
abstract class Socket

        # Underlying C socket
        private var native: NativeSocket is noinit

        # Is this socket closed?
        var closed = false

        # Set whether calls to `accept` are blocking
        fun blocking=(value: Bool)
        do
                # We use the opposite from the native version as the native API
                # is closer to the C API. In the Nity API, we use a positive version
                # of the name.
                native.non_blocking = not value
        end
end

# A general TCP socket, either a `TCPStream` or a `TCPServer`
abstract class TCPSocket
        super Socket

        # Port used by the socket
        var port: Int

        # IPv4 address to which `self` is connected
        #
        # Formatted as xxx.xxx.xxx.xxx.
        var address: String is noinit
end

# Simple communication stream with a remote socket
class TCPStream
        super TCPSocket
        super BufferedReader
        super Writer
        super PollableReader

        # Real canonical name of the host to which `self` is connected
        var host: String

        private var addrin: NativeSocketAddrIn is noinit

        redef var end_reached = false

        # TODO make init private

        # Creates a socket connection to host `host` on port `port`
        init connect(host: String, port: Int)
        do
                _buffer = new NativeString(1024)
                _buffer_pos = 0
                native = new NativeSocket.socket(new NativeSocketAddressFamilies.af_inet,
                        new NativeSocketTypes.sock_stream, new NativeSocketProtocolFamilies.pf_null)
                if native.address_is_null then
                        end_reached = true
                        closed = true
                        return
                end
                if not native.setsockopt(new NativeSocketOptLevels.socket, new NativeSocketOptNames.reuseaddr, 1) then
                        end_reached = true
                        closed = true
                        return
                end

                var hostent = sys.gethostbyname(host.to_cstring)
                if hostent.address_is_null then
                        # Error in name lookup
                        last_error = new IOError.from_h_errno

                        closed = true
                        end_reached = true

                        return
                end

                addrin = new NativeSocketAddrIn
                addrin.fill_from_hostent hostent
                addrin.port = port

                address = addrin.address.to_s
                init(addrin.port, hostent.h_name.to_s)

                closed = not internal_connect
                end_reached = closed
                if closed then
                        # Connection failed
                        last_error = new IOError.from_errno
                end

                prepare_buffer(1024)
        end

        # Creates a client socket, this is meant to be used by accept only
        private init server_side(h: SocketAcceptResult)
        do
                native = h.socket
                addrin = h.addr_in
                address = addrin.address.to_s

                init(addrin.port, address)

                prepare_buffer(1024)
        end

        redef fun poll_in do return ready_to_read(0)

        # Returns an array containing an enum of the events ready to be read
        #
        # event_types : Combination of several event types to watch
        #
        # timeout : Time in milliseconds before stopping listening for events on this socket
        private fun pollin(event_types: Array[NativeSocketPollValues], timeout: Int): Array[NativeSocketPollValues] do
                if end_reached then return new Array[NativeSocketPollValues]
                return native.socket_poll(new PollFD(native.descriptor, event_types), timeout)
        end

        # Easier use of pollin to check for something to read on all channels of any priority
        #
        # timeout : Time in milliseconds before stopping to wait for events
        fun ready_to_read(timeout: Int): Bool
        do
                if _buffer_pos < _buffer_length then return true
                if end_reached then return false
                var events = [new NativeSocketPollValues.pollin]
                return pollin(events, timeout).length != 0
        end

        # Checks if the socket still is connected
        fun connected: Bool
        do
                if closed then return false
                var events = [new NativeSocketPollValues.pollhup, new NativeSocketPollValues.pollerr]
                if pollin(events, 0).length == 0 then
                        return true
                else
                        closed = true
                        return false
                end
        end

        redef fun is_writable do return not end_reached

        # Establishes a connection to socket addrin
        #
        # REQUIRES : not self.end_reached
        private fun internal_connect: Bool
        do
                assert not closed
                return native.connect(addrin) >= 0
        end

        # If socket.end_reached, nothing will happen
        redef fun write(msg)
        do
                if closed then return
                native.write(msg.to_cstring, msg.length)
        end

        redef fun write_byte(value)
        do
                if closed then return
                native.write_byte value
        end

        redef fun write_bytes(bytes) do
                if closed then return
                var s = bytes.to_s
                native.write(s.to_cstring, s.length)
        end

        fun write_ln(msg: Text)
        do
                if closed then return
                write msg.to_s
                write "\n"
        end

        redef fun fill_buffer
        do
                if not connected then return

                var read = native.read(_buffer, _buffer_capacity)
                if read == -1 then
                        close
                        end_reached = true
                end

                _buffer_length = read
                _buffer_pos = 0
        end

        fun enlarge(len: Int) do
                if _buffer_capacity >= len then return
                _buffer_capacity = len

                var ns = new NativeString(_buffer_capacity)
                _buffer.copy_to(ns, _buffer_length - _buffer_pos, _buffer_pos, 0)
                _buffer = ns
        end

        redef fun close
        do
                if closed then return
                if native.close >= 0 then
                        closed = true
                        end_reached = true
                end
        end

        # Send the data present in the socket buffer
        fun flush
        do
                if not native.setsockopt(new NativeSocketOptLevels.tcp, new NativeSocketOptNames.tcp_nodelay, 1) or
                   not native.setsockopt(new NativeSocketOptLevels.tcp, new NativeSocketOptNames.tcp_nodelay, 0) then
                        closed = true
                end
        end
end

# A socket listening on a given `port` for incomming connections
#
# Create streams to communicate with clients using `accept`.
class TCPServer
        super TCPSocket

        private var addrin: NativeSocketAddrIn is noinit

        # Create and bind a listening server socket on port `port`
        init
        do
                native = new NativeSocket.socket(new NativeSocketAddressFamilies.af_inet,
                        new NativeSocketTypes.sock_stream, new NativeSocketProtocolFamilies.pf_null)
                assert not native.address_is_null
                if not native.setsockopt(new NativeSocketOptLevels.socket, new NativeSocketOptNames.reuseaddr, 1) then
                        closed = true
                        return
                end

                addrin = new NativeSocketAddrIn
                addrin.family = new NativeSocketAddressFamilies.af_inet
                addrin.port = port
                addrin.address_any

                address = addrin.address.to_s

                # Bind it
                closed = not bind
        end

        # Associates the socket to a local address and port
        #
        # Returns whether the socket has been be bound.
        private fun bind: Bool do
                return native.bind(addrin) >= 0
        end

        # Sets the socket as ready to accept incoming connections, `size` is the maximum number of queued clients
        #
        # Returns `true` if the socket could be set, `false` otherwise
        fun listen(size: Int): Bool do
                return native.listen(size) >= 0
        end

        # Accepts an incoming connection from a client
        #
        # Create and return a new socket to the client. May return null if not
        # `blocking` and there's no waiting clients, or upon an interruption
        # (whether `blocking` or not).
        #
        # Require: not closed
        fun accept: nullable TCPStream
        do
                assert not closed
                var native = native.accept
                if native == null then return null
                return new TCPStream.server_side(native)
        end

        # Close this socket
        fun close
        do
                # FIXME unify with `SocketStream::close` when we can use qualified names

                if closed then return
                if native.close >= 0 then
                        closed = true
                end
        end
end

# A simple set of sockets used by `SocketObserver`
class SocketSet
        private var native = new NativeSocketSet

        init do clear

        # Add `socket` to this set
        fun add(socket: Socket) do native.set(socket.native)

        # Remove `socket` from this set
        fun remove(socket: Socket) do native.clear(socket.native)

        # Does this set has `socket`?
        fun has(socket: Socket): Bool do return native.is_set(socket.native)

        # Clear all sockets from this set
        fun clear do native.zero
end

# Service class to manage calls to `select`
class SocketObserver
        private var native = new NativeSocketObserver

        var read_set: nullable SocketSet = null

        var write_set: nullable SocketSet = null

        var except_set: nullable SocketSet = null

        init(read: Bool, write: Bool, except: Bool)
        is old_style_init do
                if read then read_set = new SocketSet
                if write then write_set = new SocketSet
                if except then except_set = new SocketSet
        end

        fun select(max: Socket, seconds: Int, microseconds: Int): Bool
        do
                # FIXME this implementation (see the call to nullable attributes below) and
                # `NativeSockectObserver::select` is not stable.

                var timeval = new NativeTimeval(seconds, microseconds)
                return native.select(max.native, read_set.native, write_set.native, except_set.native, timeval) > 0
        end
end

# Socket over UDP, sends and receive data without the need for a connection
class UDPSocket
        super Socket

        # Last error raised by this socket
        var error: nullable Error = null

        init do native = new NativeSocket.socket(
                        new NativeSocketAddressFamilies.af_inet,
                        new NativeSocketTypes.sock_dgram,
                        new NativeSocketProtocolFamilies.pf_null)

        # Bind this socket to an `address`, on `port` (to all addresses if `null`)
        #
        # On error, sets `error` appropriately.
        fun bind(address: nullable Text, port: Int)
        do
                var addr_in = new NativeSocketAddrIn
                addr_in.port = port
                if address != null then
                        # FIXME replace all use of gethostbyname with something not obsolete
                        var hostent = sys.gethostbyname(address.to_cstring)
                        if hostent.address_is_null then
                                error = new IOError.from_h_errno
                                addr_in.free
                                return
                        end

                        addr_in.fill_from_hostent hostent
                else
                        addr_in.family = new NativeSocketAddressFamilies.af_inet
                        addr_in.address_any
                end

                if native.bind(addr_in) != 0 then error = new IOError.from_errno

                addr_in.free
        end

        # Receive `length` bytes of data from any sender
        #
        # On error, returns an empty string and sets `error` appropriately.
        fun recv(length: Int): String
        do
                var buf = new NativeString(length)
                var len = native.recvfrom(buf, length, 0, new NativeSocketAddrIn.nul)
                if len == -1 then
                        error = new IOError.from_errno
                        return ""
                end
                return buf.to_s_with_length(len)
        end

        # Receive `length` bytes of data from any sender and store the sender info in `sender.item`
        #
        # On error, returns an empty string and sets `error` appropriately.
        fun recv_from(length: Int, sender: Ref[nullable SocketAddress]): String
        do
                var src = new NativeSocketAddrIn
                var buf = new NativeString(length)

                var len = native.recvfrom(buf, length, 0, src)
                if len == -1 then
                        error = new IOError.from_errno
                        src.free
                        return ""
                end

                sender.item = new SocketAddress(src)
                return buf.to_s_with_length(len)
        end

        # Send `data` to `dest_address` on `port`
        #
        # On error, sets `error` appropriately.
        fun send_to(dest_address: Text, port: Int, data: Text)
        do
                var hostent = sys.gethostbyname(dest_address.to_cstring)
                if hostent.address_is_null then
                        error = new IOError.from_h_errno
                        return
                end

                var dest = new NativeSocketAddrIn
                dest.fill_from_hostent hostent
                dest.port = port
                native.setsockopt(new NativeSocketOptLevels.socket, new NativeSocketOptNames.broadcast, 1)

                var buf = data.to_cstring
                if native.sendto(buf, data.length, 0, dest) == -1 then
                        error = new IOError.from_errno
                end
                dest.free
        end

        # Enable broadcasting for this socket
        #
        # On error, sets `error` appropriately.
        fun enable_broadcast=(value: Bool) do
                var res = native.setsockopt(new NativeSocketOptLevels.socket, new NativeSocketOptNames.broadcast, value.to_i)
                if res == -1 then error = new IOError.from_errno
        end

        # Broadcast `data` on the network on `port`
        #
        # On error, sets `error` appropriately.
        #
        # Require: setting `enable_broadcast = true`
        fun broadcast(port: Int, data: Text)
        do
                var addr_in = new NativeSocketAddrIn
                addr_in.port = port
                addr_in.family = new NativeSocketAddressFamilies.af_inet
                addr_in.address_broadcast

                var buf = data.to_cstring
                if native.sendto(buf, data.length, 0, addr_in) == -1 then
                        error = new IOError.from_errno
                end

                addr_in.free
        end
end

# Address of a socket in the Internet namespace
#
# Used in one of the out parameters of `UDPSocket::recv_from`.
class SocketAddress
        super FinalizableOnce

        # FIXME make init private

        private var native: NativeSocketAddrIn

        init
        do
                address = native.address.to_s
                port = native.port
        end

        # Internet address
        var address: String is noinit

        # Port of the socket
        var port: Int is noinit

        redef fun ==(o) do return o isa SocketAddress and o.address == address and o.port == port

        redef fun finalize_once do native.free
end

redef class IOError
        # Fill a new `IOError` from the message of `errno`
        init from_errno do init errno.strerror

        # Fill a new `IOError` from the message of `h_errno`
        #
        # Used with `gethostbyname`.
        init from_h_errno do init h_errno.to_s
end