package eio

err e is Eio.Exn.create (Net e)

IP addresses.

Network addresses.

connect ~sw t addr is a new socket connected to remote address addr.

The new socket will be closed when sw finishes, unless closed manually first.

with_tcp_connect ~host ~service t f creates a tcp connection conn to host and service and executes f conn.

conn is closed after f returns (if it isn't already closed by then).

host is either an IP address or a domain name, eg. "www.example.org", "www.ocaml.org" or "127.0.0.1".

service is an IANA recognized service name or port number, eg. "http", "ftp", "8080" etc. See https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml.

Addresses are tried in the order they are returned by getaddrinfo, until one succeeds.

• parameter timeout

  Limits how long to wait for each connection attempt before moving on to the next. By default there is no timeout (beyond what the underlying network does).

• raises Connection_failure

  A connection couldn't be established for any of the addresses defined for host.

listen ~sw ~backlog t addr is a new listening socket bound to local address addr.

The new socket will be closed when sw finishes, unless closed manually first.

For (non-abstract) Unix domain sockets, the path will be removed afterwards.

• parameter backlog

  The number of pending connections that can be queued up (see listen(2)).

• parameter reuse_addr

  Set the Unix.socket_bool_option.SO_REUSEADDR socket option. For Unix paths, also remove any stale left-over socket.

• parameter reuse_port

  Set the Unix.socket_bool_option.SO_REUSEPORT socket option.

accept ~sw socket waits until a new connection is ready on socket and returns it.

The new socket will be closed automatically when sw finishes, if not closed earlier. If you want to handle multiple connections, consider using accept_fork instead.

connection_handler handles incoming connections from a listening socket.

accept_fork ~sw ~on_error socket fn accepts a connection and handles it in a new fiber.

After accepting a connection to socket, it runs fn flow client_addr in a new fiber.

flow will be closed when fn returns. The new fiber is attached to sw.

• parameter on_error

  Called if connection_handler raises an exception. This is typically a good place to log the error and continue. If the exception is an Eio.Io error then the caller's address is added to it.

  If you don't want to handle connection errors, use ~on_error:raise to cancel the caller's context.

  on_error is not called for Cancel.Cancelled exceptions, which do not need to be reported.

run_server ~on_error sock connection_handler establishes a concurrent socket server s.

It accepts incoming client connections on socket sock and handles them with accept_fork (see that for the description of on_error and connection_handler).

Running a Parallel Server

By default s runs on a single OCaml Domain. However, if additional_domains:(domain_mgr, domains) parameter is given, then s will spawn domains additional domains and run accept loops in those too. In such cases you must ensure that connection_handler only accesses thread-safe values. Note that having more than Domain.recommended_domain_count domains in total is likely to result in bad performance.

• parameter max_connections

  The maximum number of concurrent connections accepted by s at any time. The default is Int.max_int.

• parameter stop

  Resolving this promise causes s to stop accepting new connections. run_server will wait for all existing connections to finish and then return. This is useful to upgrade a server without clients noticing. To stop immediately, cancelling all connections, just cancel s's fiber instead.

• parameter on_error

  Connection error handler (see accept_fork).

• raises Invalid_argument

  if max_connections <= 0. if additional_domains = (domain_mgr, domains) is used and domains < 0.

datagram_socket ~sw t addr creates a new datagram socket bound to addr. The new socket will be closed when sw finishes.

`UdpV4 and `UdpV6 represents IPv4 and IPv6 datagram client sockets where the OS assigns the next available socket address and port automatically. `Udp .. can be used to create both listening server socket and client socket.

• parameter reuse_addr

  Set the Unix.socket_bool_option.SO_REUSEADDR socket option.

• parameter reuse_port

  Set the Unix.socket_bool_option.SO_REUSEPORT socket option.

send sock buf sends the data in buf using the the datagram socket sock.

• parameter dst

  If sock isn't connected, this provides the destination.

recv sock buf receives data from the socket sock putting it in buf. The number of bytes received is returned along with the sender address and port. If the buf is too small then excess bytes may be discarded depending on the type of the socket the message is received from.

getaddrinfo ?service t node returns a list of IP addresses for node. node is either a domain name or an IP address.

• parameter service

  is a human friendly textual name for internet services assigned by IANA., eg. 'http', 'https', 'ftp', etc.

  For a more thorough treatment, see getaddrinfo.

getaddrinfo_stream is like getaddrinfo, but filters out non-stream protocols.

getaddrinfo_datagram is like getaddrinfo, but filters out non-datagram protocols.

getnameinfo t sockaddr is (hostname, service) corresponding to sockaddr. hostname is the registered domain name represented by sockaddr. service is the IANA specified textual name of the port specified in sockaddr, e.g. 'ftp', 'http', 'https', etc.

Closing

close t marks the socket as closed. It can no longer be used after this.