The ACCEPT macro is issued when the server receives a connection request from a client. ACCEPT points to a socket that was created with a SOCKET macro and marked by a LISTEN macro. If a process waits for the completion of connection requests from several peer processes, a later ACCEPT macro can block until one of the CONNECT macros completes. To avoid this, issue a SELECT macro between the CONNECT and the ACCEPT macros. Concurrent server programs use the ACCEPT macro to pass connection requests to subtasks.

When issued, the ACCEPT macro takes the following actions:

1. Accepts the first connection on a queue of pending connections.
2. Creates a new socket with the same properties as the socket used in the macro and returns the address of the client for use by subsequent server macros. The new socket cannot be used to accept new connections, but can be used by the calling program for its own connection. The original socket remains available to the calling program for more connection requests.
3. Returns the new socket descriptor to the calling program.

Keyword

Description

S

Input parameter. A value or the address of a halfword binary number specifying the descriptor of the socket from which the connection is accepted.

NAME

Output parameter. Initially, the IPv4 or IPv6 application provides a pointer to the IPv4 or IPv6 socket address structure, which is filled on completion of the call with the socket address of the connection peer. Include the SYS1.MACLIB(BPXYSOCK) macro to get the assembler mappings for the socket address structure. The socket address structure mappings begin at the SOCKADDR label. The AF_INET socket address structure fields start at the SOCK_SIN label. The AF_INET6 socket address structure fields start at the SOCK_SIN6 label.

The IPv4 socket address structure contains the following fields:

Field

Description

FAMILY

A halfword binary field specifying the IPv4 addressing family. For IPv4 the value is a decimal 2, indicating AF_INET.

PORT

A halfword binary field that is set to the client port number.

IPv4-ADDRESS

A fullword binary field that is set to the 32-bit IPv4 Internet address, in network byte order, of the client host machine.

RESERVED

Specifies eight bytes of binary zeros. This field is required, but not used.

The IPv6 socket address structure contains the following fields:

Field

Description

NAMELEN

A 1-byte binary field specifying the length of this IPv6 socket address structure. Any value specified by the use of this field is ignored when processed as input and the field is set to 0 when processed as output.

FAMILY

A 1-byte binary field specifying the IPv6 addressing family. For IPv6 the value is a decimal 19, indicating AF_INET6.

PORT

A halfword binary field that is set to the client port number.

FLOW-INFO

A fullword binary field specifying the traffic class and flow label. This value of this field is undefined.

IPv6-ADDRESS

A 16-byte binary field that is set to the 128-bit IPv6 Internet address, in network byte order, of the client host machine.

SCOPE-ID

A fullword binary field which identifies a set of interfaces as appropriate for the scope of the address carried in the IPv6-ADDRESS field. For a link scope IPv6-ADDRESS, SCOPE-ID contains the link index for the IPv6-ADDRESS. For all other address scopes, SCOPE-ID is undefined.

ERRNO

Output parameter. A fullword binary field. If RETCODE is negative, ERRNO contains a valid error number. Otherwise, ignore ERRNO.

See Socket call error return codes for information about ERRNO return codes.

RETCODE

Output parameter. If RETCODE is positive, RETCODE is the new socket number.

If RETCODE is negative, check ERRNO for an error number.

Value

Description

>0

Successful call.

-1

Check ERRNO for an error code.

NS

Input parameter. A value or the address of a halfword binary number specifying the descriptor number chosen for the new socket, which is the socket for the client at the time. If NS is not specified, the interface assigns it.

ECB or REQAREA

Input parameter. This parameter is required if you are using APITYPE=3. It points to a 104-byte field containing:

For ECB

A 4-byte ECB posted by TCP/IP when the macro completes.

For REQAREA

A 4-byte user token (set by you) that is presented to your exit when the response to this function request is complete.

For ECB/REQAREA

The last 100 bytes is a storage field used by the interface to save the state information.

Note: This storage must not be modified until the macro function has completed and the ECB has been posted, or the asynchronous exit has been driven.

ERROR

Input parameter. The location in your program to receive control when the application programming interface (API) processing module cannot be loaded.

TASK

Input parameter. The location of the task storage area in your program.