docs » hs.socket

Talk to custom protocols using asynchronous TCP sockets

For UDP sockets see hs.socket.udp

hs.socket is implemented with CocoaAsyncSocket. CocoaAsyncSocket's tagging features provide a handy way to implement custom protocols.

For example, you can easily implement a basic HTTP client as follows (though using hs.http is recommended for the real world):

local TAG_HTTP_HEADER, TAG_HTTP_CONTENT = 1, 2
local body = ""
local function httpCallback(data, tag)
  if tag == TAG_HTTP_HEADER then
    print(tag, "TAG_HTTP_HEADER"); print(data)
    local contentLength = data:match("\r\nContent%-Length: (%d+)\r\n")
    client:read(tonumber(contentLength), TAG_HTTP_CONTENT)
  elseif tag == TAG_HTTP_CONTENT then
    print(tag, "TAG_HTTP_CONTENT"); print(data)
    body = data
  end
end

client = hs.socket.new(httpCallback):connect("google.com", 80)
client:write("GET /index.html HTTP/1.0\r\nHost: google.com\r\n\r\n")
client:read("\r\n\r\n", TAG_HTTP_HEADER)

Resulting in the following console output (adjust log verbosity with hs.socket.setLogLevel()) :

            LuaSkin: (secondary thread): TCP socket connected
            LuaSkin: (secondary thread): Data written to TCP socket
            LuaSkin: (secondary thread): Data read from TCP socket
1 TAG_HTTP_HEADER
HTTP/1.0 301 Moved Permanently
Location: http://www.google.com/index.html
Content-Type: text/html; charset=UTF-8
Date: Thu, 03 Mar 2016 08:38:02 GMT
Expires: Sat, 02 Apr 2016 08:38:02 GMT
Cache-Control: public, max-age=2592000
Server: gws
Content-Length: 229
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN

            LuaSkin: (secondary thread): Data read from TCP socket
2 TAG_HTTP_CONTENT
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="http://www.google.com/index.html">here</A>.
</BODY></HTML>
            LuaSkin: (secondary thread): TCP socket disconnected Socket closed by remote peer

Submodules

API Overview

API Documentation

Variables

timeout
Signature hs.socket.timeout
Type Variable
Description Timeout for the socket operations, in seconds. New [`hs.socket`](#new) objects will be created with this timeout value, but can individually change it with the [`setTimeout`](#setTimeout) method
Source extensions/socket/socket.lua line 162

Functions

parseAddress
Signature hs.socket.parseAddress(sockaddr) -> table or nil
Type Function
Description Parses a binary socket address structure into a readable table
Parameters
Returns
  • A table describing the address with the following keys or nil:
  • host - A string containing the host IP
  • port - A number containing the port
  • addressFamily - A number containing the address family
Notes
  • Some address family definitions from <sys/socket.h>:

address family | number | description :--- | :--- | : AF_UNSPEC | 0 | unspecified AF_UNIX | 1 | local to host (pipes) AF_LOCAL | AF_UNIX | backward compatibility AF_INET | 2 | internetwork: UDP, TCP, etc. AF_NS | 6 | XEROX NS protocols AF_CCITT | 10 | CCITT protocols, X.25 etc AF_APPLETALK | 16 | Apple Talk AF_ROUTE | 17 | Internal Routing Protocol AF_LINK | 18 | Link layer interface AF_INET6 | 30 | IPv6

Source extensions/socket/libsocket.m line 187

Constructors

new
Signature hs.socket.new([fn]) -> hs.socket object
Type Constructor
Description Creates an unconnected asynchronous TCP socket object
Parameters
  • fn - An optional callback function for reading data from the socket, settable here for convenience
Returns
Source extensions/socket/libsocket.m line 154
server
Signature hs.socket.server(port|path[, fn]) -> hs.socket object
Type Constructor
Description Creates and binds an [`hs.socket`](#new) instance to a port or path (Unix domain socket) for listening
Parameters
  • port - A port number [0-65535]. Ports [1-1023] are privileged. Port 0 allows the OS to select any available port
  • path - A string containing the path to the Unix domain socket
  • fn - An optional callback function for reading data from the socket, settable here for convenience
Returns
Source extensions/socket/socket.lua line 184

Methods

connect
Signature hs.socket:connect({host, port}|path[, fn]) -> self or nil
Type Method
Description Connects an unconnected [`hs.socket`](#new) instance
Parameters
  • host - A string containing the hostname or IP address
  • port - A port number [1-65535]
  • path - A string containing the path to the Unix domain socket
  • fn - An optional single-use callback function to execute after establishing the connection. Receives no parameters
Returns
  • The hs.socket object or nil if an error occurred
Notes
  • Either a host/port pair OR a Unix domain socket path must be supplied. If no port is passed, the first param is assumed to be a path to the socket file
Source extensions/socket/libsocket.m line 234
connected
Signature hs.socket:connected() -> bool
Type Method
Description Returns the connection status of the [`hs.socket`](#new) instance
Parameters
  • None
Returns
  • true if connected, otherwise false
Source extensions/socket/libsocket.m line 575
connections
Signature hs.socket:connections() -> number
Type Method
Description Returns the number of connections to the socket, which is at most 1 for default (non-listening) sockets
Parameters
  • None
Returns
  • The number of connections to the socket
Source extensions/socket/libsocket.m line 593
disconnect
Signature hs.socket:disconnect() -> self
Type Method
Description Disconnects the [`hs.socket`](#new) instance, freeing it for reuse
Parameters
  • None
Returns
Notes
  • If called on a listening socket with multiple connections, each client is disconnected
Source extensions/socket/libsocket.m line 345
info
Signature hs.socket:info() -> table
Type Method
Description Returns information on the [`hs.socket`](#new) instance
Parameters
  • None
Returns
  • A table containing the following keys:
  • connectedAddress - string (sockaddr struct)
  • connectedHost - string
  • connectedPort - number
  • connectedURL - string
  • connections - number
  • isConnected - boolean
  • isDisconnected - boolean
  • isIPv4 - boolean
  • isIPv4Enabled - boolean
  • isIPv4PreferredOverIPv6 - boolean
  • isIPv6 - boolean
  • isIPv6Enabled - boolean
  • isSecure - boolean
  • localAddress - string (sockaddr struct)
  • localHost - string
  • localPort - number
  • timeout - number
  • unixSocketPath - string
  • userData - string
Source extensions/socket/libsocket.m line 611
listen
Signature hs.socket:listen(port|path) -> self or nil
Type Method
Description Binds an unconnected [`hs.socket`](#new) instance to a port or path (Unix domain socket) for listening
Parameters
  • port - A port number [0-65535]. Ports [1-1023] are privileged. Port 0 allows the OS to select any available port
  • path - A string containing the path to the Unix domain socket
Returns
  • The hs.socket object or nil if an error occurred
Source extensions/socket/libsocket.m line 297
read
Signature hs.socket:read(delimiter[, tag]) -> self or nil
Type Method
Description Read data from the socket. Results are passed to the [callback function](#setCallback), which must be set to use this method
Parameters
  • delimiter - Either a number of bytes to read, or a string delimiter such as "&#92;n" or "&#92;r&#92;n". Data is read up to and including the delimiter
  • tag - An optional integer to assist with labeling reads. It is passed to the callback to assist with implementing state machines for processing complex protocols
Returns
  • The hs.socket object or nil if an error occured
Notes
  • If called on a listening socket with multiple connections, data is read from each of them
Source extensions/socket/libsocket.m line 369
receive
Signature hs.socket:receive(delimiter[, tag]) -> self
Type Method
Description Alias for [`hs.socket:read`](#read)
Parameters
Returns
Source extensions/socket/socket.lua line 219
send
Signature hs.socket:send(message[, tag]) -> self
Type Method
Description Alias for [`hs.socket:write`](#write)
Parameters
Returns
Source extensions/socket/socket.lua line 225
setCallback
Signature hs.socket:setCallback([fn]) -> self
Type Method
Description Sets the read callback for the [`hs.socket`](#new) instance. Must be set to read data from the socket
Parameters
  • fn - An optional callback function to process data read from the socket. nil or no argument clears the callback. The callback receives 2 parameters:
    • data - The data read from the socket as a string
    • tag - The integer tag associated with the read call, which defaults to -1
Returns
Source extensions/socket/libsocket.m line 472
setTimeout
Signature hs.socket:setTimeout(timeout) -> self
Type Method
Description Sets the timeout for the socket operations. If the timeout value is negative, the operations will not use a timeout, which is the default
Parameters
  • timeout - A number containing the timeout duration, in seconds
Returns
Source extensions/socket/libsocket.m line 499
startTLS
Signature hs.socket:startTLS([verify][, peerName]) -> self
Type Method
Description Secures the socket with TLS. The socket will disconnect immediately if TLS negotiation fails
Parameters
  • verify - An optional boolean that, if false, allows TLS handshaking with servers with self-signed certificates and does not evaluate the chain of trust. Defaults to true and omitted if peerName is supplied
  • peerName - An optional string containing the fully qualified domain name of the peer to validate against — for example, store.apple.com. It should match the name in the X.509 certificate given by the remote party. See notes below
Returns
Notes
  • IMPORTANT SECURITY NOTE:

The default settings will check to make sure the remote party's certificate is signed by a trusted 3rd party certificate agency (e.g. verisign) and that the certificate is not expired. However it will not verify the name on the certificate unless you give it a name to verify against via peerName. The security implications of this are important to understand. Imagine you are attempting to create a secure connection to MySecureServer.com, but your socket gets directed to MaliciousServer.com because of a hacked DNS server. If you simply use the default settings, and MaliciousServer.com has a valid certificate, the default settings will not detect any problems since the certificate is valid. To properly secure your connection in this particular scenario you should set peerName to "MySecureServer.com".

Source extensions/socket/libsocket.m line 520
write
Signature hs.socket:write(message[, tag][, fn]) -> self
Type Method
Description Write data to the socket
Parameters
  • message - A string containing data to be sent on the socket
  • tag - An optional integer to assist with labeling writes
  • fn - An optional single-use callback function to execute after writing data to the socket. Receives the tag parameter
Returns
Notes
  • If called on a listening socket with multiple connections, data is broadcasted to all connected sockets
Source extensions/socket/libsocket.m line 428