The SENDMSG macro sends messages on a socket with descriptor s passed in an array of messages.

Keyword

Description

S

Input parameter. A value or the address of a halfword binary number specifying the socket descriptor.

MSG

On input, this is a pointer to a message header into which the message is received on completion of the call.

NAME

On input, a pointer to a buffer where the sender's IPv4 or IPv6 address will be stored on completion of the call. The storage being pointed to should be for an IPv4 or IPv6 socket address. 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 number specifying the IPv4 addressing family. The value for the IPv4 socket descriptor (S parameter) is a decimal 2, indicating AF_INET.

PORT

A halfword binary number specifying the port number of the sending socket.

IPv4-ADDRESS

A fullword binary number specifying the 32-bit IPv4 Internet address of the sending socket.

RESERVED

An 8-byte reserved field. This field is required, but is 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. The value for the IPv6 socket descriptor (S parameter) is a decimal 19, indicating AF_INET6.

PORT

A halfword binary number specifying the port number of the sending socket.

FLOW-INFO

A fullword binary field specifying the traffic class and flow label. This field must be set to 0.

IPv6-ADDRESS

16-byte binary field specifying the 128-bit IPv6 Internet address, in network byte order, of the sending socket.

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. A value of 0 indicates the SCOPE-ID field does not identify the set of interfaces to be used, and can be specified for any address types and scopes. For a link scope IPv6-ADDRESS, SCOPE-ID can specify a link index which identifies a set of interfaces. For all other address scopes, SCOPE-ID can be set to 0.

IOV

A pointer to an array of three fullword structures with the number of structures equal to the value in IOVCNT and the format of the structures as follows:

Fullword 1

Input parameter. The address of a data buffer.

Fullword 2

Input parameter. The ALET for this buffer. If the buffer is in the primary address space, this should be zeros.

If a nonzero ALET is specified, the ALET must represent a valid entry in the dispatchable unit access list (DU-AL) for the task issuing this call. Note that ALETs can be specified only for synchronous socket calls (for example, ECB/REQAREA cannot be specified). An exception to this is an ALET representing a SCOPE=COMMON data space.

Fullword 3

Input parameter. The length of the data buffer referenced in Fullword 1.

IOVCNT

A pointer to a fullword binary field specifying the number of data buffers provided for this call.

ACCRIGHTS

A pointer to the access rights sent. This field is ignored.

ACCRLEN

A pointer to the length of the access rights sent. This field is ignored.

FLAGS

Input parameter. FLAGS can be a literal value or a fullword binary field:

Literal Value	Binary Value	Description
'MSG_OOB'	X'00000001'	Send out-of-band data. (Stream sockets only.)
'MSG_DONTROUTE'	X'00000004'	Do not route. Routing is handled by the calling program.

ERRNO

Output parameter. A fullword binary field. If RETCODE is negative, this contains an error number.

RETCODE

Output parameter. A fullword binary field.

Value

Description

0 or >0

A successful call. The value is set to the number of bytes transmitted.

-1

Check ERRNO for an error code.

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.