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target_alloc(3)			 Arcan Lua API		       target_alloc(3)

NAME
       target_alloc  -	Bind an	external connection point or force-push	a sub-
       segment

SYNOPSIS
       vid:new_vid, aid:new_aid, int:new_cookie
       target_alloc( string:cpoint, function:callback )
       target_alloc( string:cpoint, string:passkey, function:callback )
       target_alloc(  string:cpoint,  string:passkey,  int:w,	int:h,	 func-
       tion:callback )
       target_alloc( string:cpoint, int:w, int:h, function:callback )
       target_alloc( vid:fsrv )
       target_alloc( vid:fsrv, function:callback )
       target_alloc( vid:fsrv, int:w, int:h, function:callback )
       target_alloc( vid:fsrv, function:callback, string:type )
       target_alloc( vid:fsrv, function:callback, number:tag )
       target_alloc( vid:fsrv, int:w, int:h, function:callback,	string:type )
       target_alloc(  vid:fsrv,	 int:w,	int:h, function:callback, string:type,
       bool:forced )

DESCRIPTION
       This functions controls server-side initiated allocation	of segments or
       connection points. If the initial argument is of	the cpoint  form,  the
       allocation  will	be a named connection point to which a client can con-
       nect. If	the initial argument is	of the fsrv  form, a  subsegment  will
       be  allocated  and  pushed to the client. This form is more specialised
       and intended as a server-side  means  of	 requesting  and  probing  for
       client-	side support for alternate views of whatever the fsrv  connec-
       tion current presents. This can be further  specified  by  providing  a
       type   (debug, accessibility) and if a backend implementation should be
       forced or not (default=false). The form and use for callback    is  the
       same  as	 in launch_target , please refer to that function for detailed
       documentation. The optional passkey  form is an	aditional  authentica-
       tion  string  that  the connecting client is expected to	be able	to au-
       thenticate against in a platform	defined	function, typically as a  sim-
       ple  string  comparison	or challenge-response and is not intended as a
       strong means of authentication. For  such  cases,  the  launch_target
       mechanism combined with the target/configuration	database is preferred,
       as  only	 the connection	itself will be authenticated, the contents can
       still be	subject	to interception	and tampering by a local attacker.

NOTES
       1      To push new  output  segments,  see  define_recordtarget	,  de-
	      fine_nulltarget  and define_feedtarget .

       2      Each  call  that	allows	a non-authoritative connection is only
	      valid once, if a connection fail to verify OR  a	connection  is
	      completed, the connection	point will be removed.

       3      The  connection key is limited to	30 characters from the set [a-
	      Z,_0-9] and the actual search path / mechanism is	implementation
	      defined.

       4      The first	example	below will continuously	listen for new connec-
	      tions under the 'nonauth'	key. In	a real-world setting, be  sure
	      to  restrict  the	number of allowed connections to avoid running
	      out of resources and to monitor for suspicious activities	e.g. a
	      high amount of connections or connection	attempts  in  a	 short
	      timeframe	etc.

       5      The  connection  point  is  consumed (closed, unlinked) when the
	      first verified connection	goes through. To re-use	the connection
	      point, invoke target_alloc again with the	same key  from	within
	      the callback handler.

       6      for  honoring explicit requests from a frameserver regarding new
	      subsegments, use the accept_target function.

       7      When a 'connected' event has been	 received,  many  applications
	      expect  a	 displayhint  event before being able to proceed (with
	      information about	the current surface dimensions and density)

EXAMPLE
       function	target_alloc0()
	     local chain_call =	function()
		   target_alloc("nonauth", function(source, status)
			 print(source, status.kind);
			 if (status.kind == "connected") then
			       chain_call();
			 end
		   end);
	     end
       end

MISUSE
       function	target_alloc0()
	     local a = fill_surface(32,	32, 255, 0, 0, 0);
	     target_alloc(a, function(source, status)
	     end);
       end

MISUSE
       function	target_alloc1()
	     vid = net_listen();
	     target_alloc(vid, target_alloc);
       end

SEE ALSO:
       define_recordtarget(3) accept_target(3)

targetcontrol			  April	2025		       target_alloc(3)

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