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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.

Notes
  • New hs.socket objects will be created with this timeout value, but can individually change it with the hs.socket:setTimeout method.

  • If the timeout value is negative, the operations will not use a timeout. The default value is -1.

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 a TCP socket, and binds it to either 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 190

Methods

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

Connects an unconnected socket.

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. The callback 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 parameter 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 socket.

Parameters
  • None
Returns
  • true if the socket is connected, otherwise false.
Notes
  • If the socket is bound for listening, this method returns true if there is at least one connection.
Source extensions/socket/libsocket.m line 572
connections
Signature hs.socket:connections() -> number
Type Method
Description

Returns the number of connections to the socket.

Parameters
  • None
Returns
  • The number of connections to the socket.
Notes
  • This method returns at most 1 for default (non-listening) sockets.
Source extensions/socket/libsocket.m line 593
disconnect
Signature hs.socket:disconnect() -> self
Type Method
Description

Disconnects the socket, 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 about the socket.

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 614
listen
Signature hs.socket:listen(port|path) -> self or nil
Type Method
Description

Binds an unconnected socket to either 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.

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 occurred.
Notes
  • Results are passed to the socket's callback function, which must be set to use this method.
  • 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

Parameters
Returns
Source extensions/socket/socket.lua line 225
send
Signature hs.socket:send(message[, tag]) -> self
Type Method
Description

Alias for hs.socket:write

Parameters
Returns
Source extensions/socket/socket.lua line 231
setCallback
Signature hs.socket:setCallback([fn]) -> self
Type Method
Description

Sets the read callback for 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
Notes
  • A callback must be set in order to read data from the socket.
Source extensions/socket/libsocket.m line 473
setTimeout
Signature hs.socket:setTimeout(timeout) -> self
Type Method
Description

Sets the timeout for the socket operations.

Parameters
  • timeout - A number containing the timeout duration, in seconds.
Returns
Notes
  • If the timeout value is negative, the operations will not use a timeout, which is the default.
Source extensions/socket/libsocket.m line 503
startTLS
Signature hs.socket:startTLS([verify][, peerName]) -> self
Type Method
Description

Secures the socket with TLS.

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 the important security note below.
Returns
Notes
  • The socket will disconnect immediately if TLS negotiation fails.
  • 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 527
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. The callback receives the tag parameter provided here.
Returns
Notes
  • If called on a listening socket with multiple connections, data is broadcast to all connected sockets.
Source extensions/socket/libsocket.m line 429

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Licensed under the MIT License.
https://www.hammerspoon.org/docs/hs.socket.html