esockd

Erlang General Non-blocking TCP/SSL Socket Server.

Features

• General Non-blocking TCP/SSL Socket Server
• Acceptor Pool and Asynchronous TCP Accept
• UDP/DTLS Server
• Max connections management
• Allow/Deny by peer address
• Proxy Protocol V1/V2
• Keepalive Support
• Rate Limit
• IPv6 Support

Usage

A Simple TCP Echo Server:

-module(echo_server).

-export([start_link/2, init/2]).

start_link(Transport, Sock) ->
    {ok, spawn_link(?MODULE, init, [Transport, Sock])}.

init(Transport, Sock) ->
    case Transport:wait(Sock) of
        {ok, NewSock} ->
            loop(Transport, NewSock);
        Error -> Error
    end.

loop(Transport, Sock) ->
    case Transport:recv(Sock, 0) of
        {ok, Data} ->
            {ok, Peername} = Transport:peername(Sock),
            Transport:send(Sock, Data),
            loop(Transport, Sock);
        {error, Reason} ->
            io:format("TCP Error: ~s~n", [Reason]),
            {stop, Reason}
    end.

Setup Echo Server:

%% Start esockd application
ok = esockd:start().
Options = [{acceptors, 10}, {max_connections, 1024}, {tcp_options, [binary, {reuseaddr, true}]}].
MFArgs = {echo_server, start_link, []},
esockd:open(echo, 5000, Options, MFArgs).

Examples

Example	Description
examples/async_recv	prim_net async recv/send
examples/gen_server	gen_server behaviour
examples/simple	simple echo server
examples/ssl	ssl echo server
examples/proxy_protocol	proxy protocol v1/2
examples/udp	udp echo server
examples/dtls	dtls echo server

API

Open a listener

esockd:open(echo, 5000, [{tcp_options, [binary, {reuseaddr, true}]}],
            {echo_server, start_link, []}).

esockd:open(echo, {"127.0.0.1", 6000}, [{tcp_options, [binary, {reuseaddr, true}]}],
            {echo_server, start_link, []}).

Spec:

-spec(open(Protocol, ListenOn, Options, MFArgs) -> {ok, pid()} | {error, term()} when
           Protocol :: atom(),
           ListenOn :: inet:port_number() | {host(), inet:port_number()}),
           Options  :: [option()],
           MFArgs   :: esockd:mfargs()).

Option:

-type(option() :: {acceptors, pos_integer()}
                | {max_connections, pos_integer()}
                | {max_conn_rate, pos_integer()}
                | {access_rules, [esockd_access:rule()]}
                | {shutdown, brutal_kill | infinity | pos_integer()}
                | tune_buffer | {tune_buffer, boolean()}
                | proxy_protocol | {proxy_protocol, boolean()}
                | {proxy_protocol_timeout, timeout()}
                | {ssl_options, [ssl:ssl_option()]}
                | {udp_options, [gen_udp:option()]}
                | {dtls_options, [gen_udp:option() | ssl:ssl_option()]}).

MFArgs:

-type(mfargs() :: atom() | {atom(), atom()} | {module(), atom(), [term()]}).

Get Setting and Stats

Get stats:

esockd:get_stats({echo, 5000}).

Get acceptors:

esockd:get_acceptors({echo, {"127.0.0.1", 6000}}).

Get/Set max connections:

esockd:get_max_connections({echo, 5000}).
esockd:set_max_connections({echo, 5000}, 100000).

Allow/Deny

Same to Allow/Deny Syntax of nginx:

allow address | CIDR | all;

deny address | CIDR | all;

allow/deny by options:

esockd:open(echo, 5000, [{access, [{deny, "192.168.1.1"}, {allow, "192.168.1.0/24"}, {deny, all}]}], MFArgs).

allow/deny by API:

esockd:allow({echo, 5000}, all).
esockd:allow({echo, 5000}, "192.168.0.1/24").
esockd:deny({echo, 5000}, all).
esockd:deny({echo, 5000}, "10.10.0.0/16").

Close a listener

esockd:close(echo, 5000).
esockd:close(echo, {"127.0.0.1", 6000}).

Spec:

-spec(close(Protocol, ListenOn) -> ok when Protocol :: atom(), ListenOn :: inet:port_number() | {host(), inet:port_number()}).

SSL

Connecting to ssl_echo_server:

openssl s_client -connect 127.0.0.1:5000 -ssl3

openssl s_client -connect 127.0.0.1:5000 -tls1

Design

Supervisor Tree

esockd_sup
    -> esockd_listener_sup
        -> esockd_listener
        -> esockd_acceptor_sup
            -> esockd_acceptor
            -> esockd_acceptor
            -> ......
        -> esockd_connection_sup
            -> esockd_connection
            -> esockd_connection
            -> ......

Acceptor

1. Acceptor Pool

2. Suspend for one second when e{n, m}file errors happened

Connection Sup

1. Create a connection, and let it run...

2. Control maximum connections

3. Count active connections

4. Count shutdown reasons

CIDR

CIDR Wiki: https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing

Benchmark

Benchmark 2.1.0-alpha release on one 8 cores, 32G memory ubuntu/14.04 server::

250K concurrent connections, 50K messages/sec, 40Mbps In/Out consumed 5G memory, 20% CPU/core

License

Apache License Version 2.0

Author

EMQ X Team.