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Inside Macintosh: Networking /

Chapter 5 - AppleTalk Data Stream Protocol (ADSP) / ADSP Reference

Routines / Establishing and Terminating an ADSP Connection Listener

dspCLListen

The dspCLListen routine causes a connection listener to listen for connection requests. You use the PBControl function to call the dspCLListen routine. See "Routines" on page 5-43 for a description of the PBControl function.

-->	ioCompletion	ProcPtr	A pointer to a completion routine.
<--	ioResult	OSErr	The function result.
-->	ioCRefNum	Integer	The driver reference number.
-->	csCode	Integer	Always dspCLListen for this function.
-->	ccbRefNum	Integer	The CCB reference number.
<--	remoteCID	Integer	The ID of the remote connection end.
<--	remoteAddress	AddrBlock	The remote internet address.
-->	filterAddress	AddrBlock	A filter for open-connection requests.
<--	sendSeq	LongInt	The initial send sequence number.
<--	sendWindow	Integer	The initial size of the remote receive queue.
<--	attnSendSeq	LongInt	The attention send sequence number.

Field Description

csCode

The routine selector, always dspCLListen for this routine.

ccbRefNum

The CCB reference number that the dspCLInit routine returned.

remoteCID

The identification number of the remote connection end. You must pass this value to the dspOpen routine when you open the connec-
tion or to the dspCLDeny routine when you deny the connection request. The dspCLListen routine returns this number.

remoteAddress

The internet address of the remote socket that sent a request to open a connection. This address consists of a 2-byte network number, a 1-byte node ID, and a 1-byte socket number. You must pass this value to the dspOpen routine when you open the connection or to the dspCLDeny routine when you deny the connection request.

filterAddress

The internet address of the socket from which you will accept a connection request. The address consists of three fields: a 2-byte network number, a 1-byte node ID, and a 1-byte socket number. Specify 0 for any of these fields for which you wish to impose no restrictions. If you specify a filter address of $00082500, for example, the connection listener accepts a connection request from any socket at node $25 of network $0008.

sendSeq

The sequence number of the first byte that the local connection end will send to the remote connection end. ADSP uses this number to coordinate communications and to check for errors. You must pass this value to the dspOpen routine when you open the connection.

sendWindow

The sequence number of the last byte that the remote connection end has buffer space to receive. ADSP uses this number to coordinate communications and to check for errors. You must pass this value to the dspOpen routine when you open the connection.

attnSendSeq

The sequence number of the next attention packet that the local connection end will transmit. ADSP uses this number to ensure that attention packets are delivered in the correct order and to check for errors. You must pass this value to the dspOpen routine when you open the connection.

DESCRIPTION

The dspCLListen routine initiates the connection listener. You must have already used the dspCLInit routine to establish a connection listener before using the dspCLListen routine. The dspCLListen routine is used only by connection servers.

When ADSP receives an open-connection request from a socket that satisfies the address requirements of the filterAddress parameter, it returns values for the remoteCID, remoteAddress, sendSeq, sendWindow, and attnSendSeq parameters and completes execution of the dspCLListen routine. You must then either accept the open-connection request by calling the dspOpen routine in the ocAccept mode or
deny the request by calling the dspCLDeny routine.

You can call the dspCLListen routine several times, specifying the same connection listener. For example, if you wanted to accept connections from any or all of three different addresses, you could call the dspCLListen routine three times with a different value for the filterAddress parameter each time. Note that you must execute the dspCLListen routine asynchronously to take advantage of this feature.

ASSEMBLY-LANGUAGE INFORMATION

To execute the dspCLListen routine from assembly language, call the _Control trap macro with a value of dspCLListen in the csCode field of the parameter block.

RESULT CODES

noErr	0	No error
errState	-1278	Not a connection listener
errAborted	-1279	Request aborted by the dspRemove routine
errRefNum	-1280	Bad connection reference number