SENDTO

SENDTO is similar to SEND, except that it includes the destination address parameter. You can use the destination address on the SENDTO macro to send datagrams on a UDP socket that is connected or not connected.

Use the FLAGS parameter to:

Send out-of-band data, such as interrupts, aborts, and data marked as urgent.
Suppress the local routing tables. This implies that the caller takes control of routing, which requires writing network software.

For datagram sockets, the SENDTO macro sends the entire datagram if the datagram fits into the buffer.

For stream sockets, data is processed as streams of information with no boundaries separating the data. For example, if a program is required to send 1000 bytes, each SENDTO macro call can send any number of bytes, up to the entire 1000 bytes, with the number of bytes sent returned in RETCODE. Therefore, programs using stream sockets should place SENDTO in a loop that repeats the macro until all data has been sent.

The following requirements apply to this call:

Authorization:

Supervisor state or problem state, any PSW key.

Dispatchable unit mode:

Task.

Cross memory mode:

PASN = HASN.

Amode:

31-bit or 24-bit.

Note: See "Addressability mode (Amode) considerations" under CALL instruction API environmental restrictions and programming requirements.

ASC mode:

Primary address space control (ASC) mode.

Interrupt status:

Enabled for interrupts.

Locks:

Unlocked.

Control parameters:

All parameters must be addressable by the caller and in the primary address space.


>>-EZASMI--TYPE=SENDTO--,S--=--+-number---+--------------------->
                               +-address--+   
                               +-*indaddr-+   
                               '-(reg)----'   

>--,NBYTE--=--+-number---+--,BUF--=--+-address--+--------------->
              +-address--+           +-*indaddr-+   
              +-*indaddr-+           '-(reg)----'   
              '-(reg)----'                          

>--,ALET--=--+-address--+--,NAME--=--+-address--+--------------->
             +-*indaddr-+            +-*indaddr-+   
             '-(reg)----'            '-(reg)----'   

>--,ERRNO--=--+-address--+--,RETCODE--=--+-address--+----------->
              +-*indaddr-+               +-*indaddr-+   
              '-(reg)----'               '-(reg)----'   

>--+--------------------------------+--------------------------->
   '-,FLAGS--=--+-'MSG_OOB'-------+-'   
                +-'MSG_DONTROUTE'-+     
                +-address---------+     
                +-*indaddr--------+     
                '-(reg)-----------'     

>--+---------------------------+--+-------------------------+--->
   +-,ECB--=--+-address--+-----+  '-,ERROR--=--+-address--+-'   
   |          +-*indaddr-+     |               +-*indaddr-+     
   |          '-(reg)----'     |               '-(reg)----'     
   '-,REQAREA--=--+-address--+-'                                
                  +-*indaddr-+                                  
                  '-(reg)----'                                  

>--+------------------------+----------------------------------><
   '-,TASK--=--+-address--+-'   
               +-*indaddr-+     
               '-(reg)----'

Keyword

Description

S

Output parameter. A value or the address of a halfword binary number specifying the socket descriptor of the socket sending the data.

NBYTE

Input parameter. A value or the address of a fullword binary number specifying the number of bytes to transmit.

BUF

Input parameter. The address of the data being transmitted. The length of BUF must be at least as long as the value of NBYTE.

ALET

Optional input parameter. A fullword binary field containing the ALET of BUF. The default is 0 (primary address space).

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.

NAME

Input parameter. The address of the IPv4 or IPv6 target. 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 must specify the following fields:

Field: Description
FAMILY: A halfword binary field containing the IPv4 addressing family. The value for the IPv4 socket descriptor (S parameter) is a decimal 2, indicating AF_INET.
PORT: A halfword binary field containing the port number bound to the socket.
IP-ADDRESS: A fullword binary field containing the 32-bit IPv4 Internet Protocol address of the socket.
RESERVED: Specifies an 8-byte reserved field. This field is required, but is not used.

The IPv6 socket structure must specify 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 IPv6 socket descriptor (S parameter) is a decimal 19, indicating AF_INET6.
PORT: A halfword binary field containing the port number bound to the socket.
FLOW-INFO: A fullword binary field specifying the traffic class and flow label. This field must be set to 0.
IPv6-ADDRESS: A 16-byte binary field that is set to the 128-bit IPv6 Internet Protocol address, in network byte order, of the client host machine. If 0 is specified, the application accepts connections from any network address.
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 must be set to 0.

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. A fullword binary field that returns one of the following values:

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.

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.

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.