TCP echo server

gleam.toml

@@ -14,6 +14,9 @@ version = "1.0.0"
 
 [dependencies]
 gleam_stdlib = ">= 0.44.0 and < 2.0.0"
+gleam_otp = ">= 1.2.0 and < 2.0.0"
+gleam_erlang = ">= 1.3.0 and < 2.0.0"
+simplifile = ">= 2.3.1 and < 3.0.0"
 
 [dev-dependencies]
 gleeunit = ">= 1.0.0 and < 2.0.0"

manifest.toml

@@ -2,10 +2,17 @@
 # You typically do not need to edit this file
 
 packages = [
+  { name = "filepath", version = "1.1.2", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "filepath", source = "hex", outer_checksum = "B06A9AF0BF10E51401D64B98E4B627F1D2E48C154967DA7AF4D0914780A6D40A" },
+  { name = "gleam_erlang", version = "1.3.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleam_erlang", source = "hex", outer_checksum = "1124AD3AA21143E5AF0FC5CF3D9529F6DB8CA03E43A55711B60B6B7B3874375C" },
+  { name = "gleam_otp", version = "1.2.0", build_tools = ["gleam"], requirements = ["gleam_erlang", "gleam_stdlib"], otp_app = "gleam_otp", source = "hex", outer_checksum = "BA6A294E295E428EC1562DC1C11EA7530DCB981E8359134BEABC8493B7B2258E" },
   { name = "gleam_stdlib", version = "0.65.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "7C69C71D8C493AE11A5184828A77110EB05A7786EBF8B25B36A72F879C3EE107" },
   { name = "gleeunit", version = "1.9.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "DA9553CE58B67924B3C631F96FE3370C49EB6D6DC6B384EC4862CC4AAA718F3C" },
+  { name = "simplifile", version = "2.3.1", build_tools = ["gleam"], requirements = ["filepath", "gleam_stdlib"], otp_app = "simplifile", source = "hex", outer_checksum = "957E0E5B75927659F1D2A1B7B75D7B9BA96FAA8D0C53EA71C4AD9CD0C6B848F6" },
 ]
 
 [requirements]
+gleam_erlang = { version = ">= 1.3.0 and < 2.0.0" }
+gleam_otp = { version = ">= 1.2.0 and < 2.0.0" }
 gleam_stdlib = { version = ">= 0.44.0 and < 2.0.0" }
 gleeunit = { version = ">= 1.0.0 and < 2.0.0" }
+simplifile = { version = ">= 2.3.1 and < 3.0.0" }

src/musicplayer.gleam

@@ -1,5 +1,5 @@
 import gleam/io
 
 pub fn main() -> Nil {
-  io.println("Hello from musicplayer!")
+  io.println("musicplayer")
 }

src/tcp/echo_server.gleam

@@ -0,0 +1,81 @@
+import gleam/erlang/process.{type Subject}
+import gleam/io
+import gleam/otp/actor
+import gleam/result
+import gleam/string
+
+import tcp/reason.{type Reason}
+import tcp/tcp
+
+pub type Message {
+  Shutdown
+  ReadyToAccept(subject: Subject(Message), listen_socket: tcp.Socket)
+}
+
+pub fn new(socket_path: String) -> Result(tcp.Socket, String) {
+  let server = actor.new(Nil) |> actor.on_message(handle_message) |> actor.start
+
+  case tcp.listen(socket_path), server {
+    Error(r), _ -> Error(reason.to_string(r))
+    _, Error(start_error) ->
+      case start_error {
+        actor.InitExited(_) -> Error("InitExited")
+        actor.InitFailed(_) -> Error("InitFailed")
+        actor.InitTimeout -> Error("InitTimeout")
+      }
+    Ok(listen_socket), Ok(b) -> {
+      let subject = b.data
+      actor.send(subject, ReadyToAccept(subject, listen_socket))
+      Ok(listen_socket)
+    }
+  }
+}
+
+fn handle_message(_: Nil, message: Message) -> actor.Next(Nil, Message) {
+  case message {
+    Shutdown -> actor.stop()
+
+    ReadyToAccept(subject, listen_socket) -> {
+      case tcp.accept(listen_socket) {
+        Error(r) ->
+          actor.stop_abnormal(
+            "Could not accept connection :" <> reason.to_string(r),
+          )
+        Ok(socket) -> {
+          case receive_from_connection(socket) {
+            Error(r) ->
+              io.println_error(
+                "Failed to receive from connection :" <> reason.to_string(r),
+              )
+            Ok(_) -> Nil
+          }
+
+          actor.send(subject, ReadyToAccept(subject, listen_socket))
+          actor.continue(Nil)
+        }
+      }
+    }
+  }
+}
+
+fn receive_from_connection(socket: tcp.Socket) -> Result(Nil, Reason) {
+  result.try(receive_until_closed(socket, ""), fn(data) {
+    let _ = tcp.send(socket, data)
+    tcp.close(socket)
+    Ok(Nil)
+  })
+}
+
+fn receive_until_closed(
+  socket: tcp.Socket,
+  result: String,
+) -> Result(String, Reason) {
+  case tcp.receive(socket, 10_000) {
+    Error(reason.Closed) -> Ok(result)
+    Error(err) -> Error(err)
+    Ok(data) -> {
+      let result = data |> string.append(result, _)
+      receive_until_closed(socket, result)
+    }
+  }
+}

src/tcp/reason.gleam

@@ -0,0 +1,243 @@
+pub type Reason {
+  /// from `connect`
+  Timeout
+  /// from `send`
+  Closed
+
+  Overflow
+
+  /// Address already in use
+  Eaddrinuse
+  /// Cannot assign requested address
+  Eaddrnotavail
+  /// Address family not supported by protocol family
+  Eafnosupport
+  /// Operation already in progress
+  Ealready
+  /// Software caused connection abort
+  Econnaborted
+  /// Connection refused
+  Econnrefused
+  /// Connection reset by peer
+  Econnreset
+  /// Destination address required
+  Edestaddrreq
+  /// Host is down
+  Ehostdown
+  /// Host is unreachable
+  Ehostunreach
+  /// Operation now in progress
+  Einprogress
+  /// Socket is already connected
+  Eisconn
+  /// Message too long
+  Emsgsize
+  /// Network is down
+  Enetdown
+  /// Network is unreachable
+  Enetunreach
+  /// Package not installed
+  Enopkg
+  /// Bad protocol option
+  Enoprotoopt
+  /// Socket is not connected
+  Enotconn
+  /// Inappropriate device for ioctl
+  Enotty
+  /// Socket operation on non-socket
+  Enotsock
+  /// Protocol error
+  Eproto
+  /// Protocol not supported
+  Eprotonosupport
+  /// Wrong protocol type for socket
+  Eprototype
+  /// Socket type not supported
+  Esocktnosupport
+  /// Connection timed out
+  Etimedout
+  /// Operation would block
+  Ewouldblock
+  /// Invalid exchange
+  Exbadport
+  /// Invalid sequence number
+  Exbadseq
+  /// Permission denied
+  Eacces
+  /// Resource temporarily unavailable
+  Eagain
+  /// Bad file number
+  Ebadf
+  /// Not a data message
+  Ebadmsg
+  /// File busy
+  Ebusy
+  /// Resource deadlock avoided
+  Edeadlk
+  /// Resource deadlock avoided
+  Edeadlock
+  /// Disk quota exceeded
+  Edquot
+  /// File already exists
+  Eexist
+  /// Bad address in system call argument
+  Efault
+  /// File too large
+  Efbig
+  /// Inappropriate file type or format
+  Eftype
+  /// Interrupted system call
+  Eintr
+  /// Invalid argument
+  Einval
+  /// I/O error
+  Eio
+  /// Illegal operation on a directory
+  Eisdir
+  /// Too many levels of symbolic links
+  Eloop
+  /// Too many open files
+  Emfile
+  /// Too many links
+  Emlink
+  /// Multihop attempted
+  Emultihop
+  /// Filename too long
+  Enametoolong
+  /// File table overflow
+  Enfile
+  /// No buffer space available
+  Enobufs
+  /// No such device
+  Enodev
+  /// No locks available
+  Enolck
+  /// Link has been severed
+  Enolink
+  /// No such file or directory
+  Enoent
+  /// Not enough memory
+  Enomem
+  /// No space left on device
+  Enospc
+  /// Out of stream resources or not a stream device
+  Enosr
+  /// Not a stream device
+  Enostr
+  /// Function not implemented
+  Enosys
+  /// Block device required
+  Enotblk
+  /// Not a directory
+  Enotdir
+  /// Operation not supported
+  Enotsup
+  /// No such device or address
+  Enxio
+  /// Operation not supported on socket
+  Eopnotsupp
+  /// Value too large for defined data type
+  Eoverflow
+  /// Not owner
+  Eperm
+  /// Broken pipe
+  Epipe
+  /// Math result unrepresentable
+  Erange
+  /// Read-only filesystem
+  Erofs
+  /// Invalid seek
+  Espipe
+  /// No such process
+  Esrch
+  /// Stale remote file handle
+  Estale
+  /// Text file or pseudo-device busy
+  Etxtbsy
+  /// Cross-device link
+  Exdev
+}
+
+pub fn to_string(reason: Reason) -> String {
+  case reason {
+    Overflow -> "overflow"
+    Closed -> "Connection closed (closed)"
+    Eacces -> "Permission denied (eacces)"
+    Eaddrinuse -> "Address already in use (eaddrinuse)"
+    Eaddrnotavail -> "Cannot assign requested address (eaddrnotavail)"
+    Eafnosupport ->
+      "Address family not supported by protocol family (eafnosupport)"
+    Eagain -> "Resource temporarily unavailable (eagain)"
+    Ealready -> "Operation already in progress (ealready)"
+    Ebadf -> "Bad file number (ebadf)"
+    Ebadmsg -> "Not a data message (ebadmsg)"
+    Ebusy -> "File busy (ebusy)"
+    Econnaborted -> "Software caused connection abort (econnaborted)"
+    Econnrefused -> "Connection refused (econnrefused)"
+    Econnreset -> "Connection reset by peer (econnreset)"
+    Edeadlk -> "Resource deadlock avoided (edeadlk)"
+    Edeadlock -> "Resource deadlock avoided (edeadlock)"
+    Edestaddrreq -> "Destination address required (edestaddrreq)"
+    Edquot -> "Disk quota exceeded (edquot)"
+    Eexist -> "File already exists (eexist)"
+    Efault -> "Bad address in system call argument (efault)"
+    Efbig -> "File too large (efbig)"
+    Eftype -> "Inappropriate file type or format (eftype)"
+    Ehostdown -> "Host is down (ehostdown)"
+    Ehostunreach -> "Host is unreachable (ehostunreach)"
+    Einprogress -> "Operation now in progress (einprogress)"
+    Eintr -> "Interrupted system call (eintr)"
+    Einval -> "Invalid argument (einval)"
+    Eio -> "I/O error (eio)"
+    Eisconn -> "Socket is already connected (eisconn)"
+    Eisdir -> "Illegal operation on a directory (eisdir)"
+    Eloop -> "Too many levels of symbolic links (eloop)"
+    Emfile -> "Too many open files (emfile)"
+    Emlink -> "Too many links (emlink)"
+    Emsgsize -> "Message too long (emsgsize)"
+    Emultihop -> "Multihop attempted (emultihop)"
+    Enametoolong -> "Filename too long (enametoolong)"
+    Enetdown -> "Network is down (enetdown)"
+    Enetunreach -> "Network is unreachable (enetunreach)"
+    Enfile -> "File table overflow (enfile)"
+    Enobufs -> "No buffer space available (enobufs)"
+    Enodev -> "No such device (enodev)"
+    Enoent -> "No such file or directory (enoent)"
+    Enolck -> "No locks available (enolck)"
+    Enolink -> "Link has been severed (enolink)"
+    Enomem -> "Not enough memory (enomem)"
+    Enopkg -> "Package not installed (enopkg)"
+    Enoprotoopt -> "Bad protocol option (enoprotoopt)"
+    Enospc -> "No space left on device (enospc)"
+    Enosr -> "Out of stream resources or not a stream device (enosr)"
+    Enostr -> "Not a stream device (enostr)"
+    Enosys -> "Function not implemented (enosys)"
+    Enotblk -> "Block device required (enotblk)"
+    Enotconn -> "Socket is not connected (enotconn)"
+    Enotdir -> "Not a directory (enotdir)"
+    Enotsock -> "Socket operation on non-socket (enotsock)"
+    Enotsup -> "Operation not supported (enotsup)"
+    Enotty -> "Inappropriate device for ioctl (enotty)"
+    Enxio -> "No such device or address (enxio)"
+    Eopnotsupp -> "Operation not supported on socket (eopnotsupp)"
+    Eoverflow -> "Value too large for defined data type (eoverflow)"
+    Eperm -> "Not owner (eperm)"
+    Epipe -> "Broken pipe (epipe)"
+    Eproto -> "Protocol error (eproto)"
+    Eprotonosupport -> "Protocol not supported (eprotonosupport)"
+    Eprototype -> "Wrong protocol type for socket (eprototype)"
+    Erange -> "Math result unrepresentable (erange)"
+    Erofs -> "Read-only filesystem (erofs)"
+    Esocktnosupport -> "Socket type not supported (esocktnosupport)"
+    Espipe -> "Invalid seek (espipe)"
+    Esrch -> "No such process (esrch)"
+    Estale -> "Stale remote file handle (estale)"
+    Etimedout -> "Connection timed out (etimedout)"
+    Etxtbsy -> "Text file or pseudo-device busy (etxtbsy)"
+    Ewouldblock -> "Operation would block (ewouldblock)"
+    Exbadport -> "Invalid exchange (exbadport)"
+    Exbadseq -> "Invalid sequence number (exbadseq)"
+    Exdev -> "Cross-device link (exdev)"
+    Timeout -> "Operation timed out (timeout)"
+  }
+}

src/tcp/tcp.gleam

@@ -0,0 +1,117 @@
+import gleam/bit_array
+import gleam/erlang/atom
+import gleam/result
+
+import tcp/reason.{type Reason}
+
+pub type Socket
+
+// https://www.erlang.org/doc/apps/kernel/inet#t:address_family/0
+// local socket
+type Local {
+  Local(socket_path: String)
+}
+
+type ModeValue {
+  Binary
+}
+
+type TCPOption {
+  Active(Bool)
+  Mode(ModeValue)
+  Reuseaddr(Bool)
+  Ifaddr(Local)
+  ExitOnClose(Bool)
+}
+
+pub fn listen(socket_path: String) -> Result(Socket, Reason) {
+  let options = [
+    Mode(Binary),
+    Active(False),
+    Reuseaddr(True),
+    Ifaddr(Local(socket_path)),
+    ExitOnClose(False),
+  ]
+  // port zero with `local` address
+  let port = 0
+
+  gen_tcp_listen(port, options)
+}
+
+pub fn accept(listen_socket: Socket) -> Result(Socket, Reason) {
+  gen_tcp_accept(listen_socket)
+}
+
+pub fn receive(socket: Socket, timeout: Int) -> Result(String, Reason) {
+  // Get all bytes
+  let length = 0
+
+  use bits <- result.try(gen_tcp_recv(socket, length, timeout))
+  case bits |> bit_array.to_string {
+    // TODO what error is best?
+    Error(_) -> Error(reason.Ebadmsg)
+    Ok(s) -> Ok(s)
+  }
+}
+
+pub fn connect(socket_path: String) -> Result(Socket, Reason) {
+  let options = [Mode(Binary), Active(False)]
+
+  // port zero with `local` address
+  let port = 0
+
+  // timeout in ms
+  let timeout = 1000
+
+  gen_tcp_connect(Local(socket_path), port, options, timeout)
+}
+
+pub fn send(socket: Socket, message: String) -> Result(Nil, Reason) {
+  gen_tcp_send(socket, bit_array.from_string(message))
+}
+
+pub fn close(socket: Socket) -> Nil {
+  gen_tcp_close(socket)
+}
+
+pub fn shutdown(socket: Socket) -> Result(Nil, Reason) {
+  let how = atom.create("write")
+  gen_tcp_shutdown(socket, how)
+}
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#listen/2
+@external(erlang, "gen_tcp", "listen")
+fn gen_tcp_listen(port: Int, option: List(TCPOption)) -> Result(Socket, Reason)
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#accept/1
+@external(erlang, "gen_tcp", "accept")
+fn gen_tcp_accept(listen_socket: Socket) -> Result(Socket, Reason)
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#recv/3
+@external(erlang, "gen_tcp", "recv")
+fn gen_tcp_recv(
+  socket: Socket,
+  length: Int,
+  timeout: Int,
+) -> Result(BitArray, Reason)
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#connect/4
+@external(erlang, "gen_tcp", "connect")
+fn gen_tcp_connect(
+  address: Local,
+  port: Int,
+  options: List(TCPOption),
+  timeout: Int,
+) -> Result(Socket, Reason)
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#send/2
+@external(erlang, "tcp_ffi", "send")
+fn gen_tcp_send(socket: Socket, packet: BitArray) -> Result(Nil, Reason)
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#close/1
+@external(erlang, "gen_tcp", "close")
+fn gen_tcp_close(socket: Socket) -> Nil
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#shutdown/2
+@external(erlang, "tcp_ffi", "shutdown")
+fn gen_tcp_shutdown(socket: Socket, how: atom.Atom) -> Result(Nil, Reason)

src/tcp/tcp_ffi.erl

@@ -0,0 +1,14 @@
+-module(tcp_ffi).
+-export([send/2, shutdown/2]).
+
+send(Socket, Packet) ->
+  case gen_tcp:send(Socket, Packet) of
+    ok -> {ok, nil};
+    Res -> Res
+  end.
+
+shutdown(Socket, How) ->
+  case gen_tcp:shutdown(Socket, How) of
+    ok -> {ok, nil};
+    Res -> Res
+  end.

test/musicplayer_test.gleam

@@ -1,13 +1,30 @@
+import gleam/list
 import gleeunit
+import simplifile
+
+import tcp/echo_server
+import tcp/tcp
 
 pub fn main() -> Nil {
   gleeunit.main()
 }
 
-// gleeunit test functions end in `_test`
-pub fn hello_world_test() {
-  let name = "Joe"
-  let greeting = "Hello, " <> name <> "!"
+pub fn tcp_send_shutdown_receive_test() {
+  let socket_path = "/tmp/musicplayer-test.sock"
 
-  assert greeting == "Hello, Joe!"
+  let assert Ok(_) = echo_server.new(socket_path)
+  let assert Ok(socket) = tcp.connect(socket_path)
+
+  let messages = ["hello, ", "world!\n"]
+  list.each(messages, fn(message) {
+    let assert Ok(_) = tcp.send(socket, message)
+  })
+
+  let assert Ok(_) = tcp.shutdown(socket)
+
+  let timeout_ms = 100
+  assert Ok("hello, world!\n") == tcp.receive(socket, timeout_ms)
+
+  // TODO find better way to always do cleanup
+  simplifile.delete(socket_path)
 }