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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 objects will be created with this timeout value, but can individually change it with the setTimeout method

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>:

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

server

| Signature | hs.socket.server(port|path[, fn]) -> hs.socket object | | -----------------------------------------------------|---------------------------------------------------------------------------------------------------------| | Type | Constructor | | Description | Creates and binds an hs.socket 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 | |

Methods

connect

| Signature | hs.socket:connect({host, port}|path[, fn]) -> self or nil | | -----------------------------------------------------|---------------------------------------------------------------------------------------------------------| | Type | Method | | Description | Connects an unconnected hs.socket 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
|

connected

Signature hs.socket:connected() -> bool
Type Method
Description Returns the connection status of the hs.socket instance
Parameters
  • None
Returns
  • true if connected, otherwise false

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

disconnect

Signature hs.socket:disconnect() -> self
Type Method
Description Disconnects the hs.socket instance, freeing it for reuse
Parameters
  • None
Returns
Notes
  • If called on a listening socket with multiple connections, each client is disconnected

info

Signature hs.socket:info() -> table
Type Method
Description Returns information on the hs.socket 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

listen

| Signature | hs.socket:listen(port|path) -> self or nil | | -----------------------------------------------------|---------------------------------------------------------------------------------------------------------| | Type | Method | | Description | Binds an unconnected hs.socket 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
|

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, which must be set to use this method
Parameters
  • delimiter - Either a number of bytes to read, or a string delimiter such as "\n" or "\r\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

receive

Signature hs.socket:receive(delimiter[, tag]) -> self
Type Method
Description Alias for hs.socket:read

send

Signature hs.socket:send(message[, tag]) -> self
Type Method
Description Alias for hs.socket:write

setCallback

Signature hs.socket:setCallback([fn]) -> self
Type Method
Description Sets the read callback for the hs.socket 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
Returns

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

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".

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