The RECVMSG call receives messages on a socket with descriptor
S and stores them in an array of message headers. If a datagram packet
is too long to fit in the supplied buffers, datagram sockets discard
extra bytes.
For datagram protocols, RECVMSG returns the source address
associated with each incoming datagram. For connection-oriented protocols
like TCP, GETPEERNAME returns the address associated with the other
end of the connection.
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.
|
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. |
Figure 1 shows an example
of RECVMSG call instructions.
WORKING-STORAGE SECTION.
01 SOC-FUNCTION PIC X(16) VALUE IS 'RECVMSG'.
01 S PIC 9(4) BINARY.
01 MSG-HDR.
03 MSG-NAME USAGE IS POINTER.
03 MSG-NAME-LEN PIC 9(8) COMP.
03 IOV USAGE IS POINTER.
03 IOVCNT USAGE IS POINTER.
03 MSG-ACCRIGHTS USAGE IS POINTER.
03 MSG-ACCRIGHTS-LEN USAGE IS POINTER.
01 FLAGS PIC 9(8) BINARY.
88 NO-FLAG VALUE IS 0.
88 OOB VALUE IS 1.
88 PEEK VALUE IS 2.
01 ERRNO PIC 9(8) BINARY.
01 RETCODE PIC S9(8) BINARY.
LINKAGE SECTION.
01 L1.
03 RECVMSG-IOVECTOR.
05 IOV1A USAGE IS POINTER.
05 IOV1AL PIC 9(8) COMP.
05 IOV1L PIC 9(8) COMP.
05 IOV2A USAGE IS POINTER.
05 IOV2AL PIC 9(8) COMP.
05 IOV2L PIC 9(8) COMP.
05 IOV3A USAGE IS POINTER.
05 IOV3AL PIC 9(8) COMP.
05 IOV3L PIC 9(8) COMP.
03 RECVMSG-BUFFER1 PIC X(16).
03 RECVMSG-BUFFER2 PIC X(16).
03 RECVMSG-BUFFER3 PIC X(16).
03 RECVMSG-BUFNO PIC 9(8) COMP.
* IPv4 socket address structure.
03 NAME.
05 FAMILY PIC 9(4) BINARY.
05 PORT PIC 9(4) BINARY.
05 IP-ADDRESS PIC 9(8) BINARY.
05 RESERVED PIC X(8).
* IPv6 socket address structure.
03 NAME.
05 FAMILY PIC 9(4) BINARY.
05 PORT PIC 9(4) BINARY.
53 FLOWINFO PIC 9(8) BINARY.
05 IP-ADDRESS.
10 FILLER PIC 9(16) BINARY.
10 FILLER PIC 9(16) BINARY.
05 SCOPE-ID PIC 9(8) BINARY.
PROCEDURE DIVISION USING L1.
SET MSG-NAME TO ADDRESS OF NAME.
MOVE LENGTH OF NAME TO MSG-NAME-LEN.
SET IOV TO ADDRESS OF RECVMSG-IOVECTOR.
MOVE 3 TO RECVMSG-BUFNO.
SET IOVCNT TO ADDRESS OF RECVMSG-BUFNO.
SET IOV1A TO ADDRESS OF RECVMSG-BUFFER1.
MOVE 0 TO IOV1AL.
MOVE LENGTH OF RECVMSG-BUFFER1 TO IOV1L.
SET IOV2A TO ADDRESS OF RECVMSG-BUFFER2.
MOVE 0 TO IOV2AL.
MOVE LENGTH OF RECVMSG-BUFFER2 TO IOV2L.
SET IOV3A TO ADDRESS OF RECVMSG-BUFFER3.
MOVE 0 TO IOV3AL.
MOVE LENGTH OF RECVMSG-BUFFER3 TO IOV3L.
SET MSG-ACCRIGHTS TO NULLS.
SET MSG-ACCRIGHTS-LEN TO NULLS.
MOVE 0 TO FLAGS.
MOVE SPACES TO RECVMSG-BUFFER1.
MOVE SPACES TO RECVMSG-BUFFER2.
MOVE SPACES TO RECVMSG-BUFFER3.
CALL 'EZASOKET' USING SOC-FUNCTION S MSG-HDR FLAGS ERRNO RETCODE.
Figure 1. RECVMSG call instruction
example