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Compaq C

Compaq C
Run-Time Library Reference Manual for OpenVMS Systems


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A.8.2 Auxiliary Communication Routines

Table A-5 lists the auxiliary communication routines. These routines are used to provide information about a socket and to set the options on a socket.

Table A-5 Auxiliary Communication Routines
Routine Description
getpeername Returns the name of the connected peer.
getsockname Returns the name associated with a socket.
getsockopt Returns the options set on a socket.
setsockopt Sets options on a socket.

A.8.3 h_errno Support Routines

Table A-6 lists the h_errno support routines. These routines map and write error-message strings generated by the external integer h_errno .

Table A-6 Supported h_errno Routines
Routine Description
herror Writes a message explaining a routine error.
hstrerror Accesses message explaining routine errors.

A.8.4 Communication Support Routines

Table A-7 lists the communication support routines. These routines perform operations such as searching databases, converting byte order of network and host addresses, reading records, and returning Internet addresses.

Table A-7 Supported Communication Routines
Routine Description
decc$get_sdc Returns the socket device's OpenVMS I/O channel associated with a socket descriptor. vaxc$get_sdc and decc$get_sdc are synonyms for the same routine.
endhostent Closes retrieval of network host entries and closes the network host file.
endnetent Closes the networks database file.
endprotoent Closes the protocols database file.
endservent Closes the network services database file.
gethostaddr Returns the standard host address for the processor.
gethostbyaddr Searches the host database for a host record with a given address.
gethostbyname Searches the host database for a host record with a given name or alias.
gethostname Returns the name of the current host.
gethostent Opens the network host entry by name from the network host database file.
getnetbyaddr Searches the network database for a network record with a given address.
getnetbyname Searches the network database for a network record with a given name or alias.
getnetent Gets a network file entry from the networks database file.
getprotobyname Searches the protocols database until a matching protocol name is found or until EOF is encountered.
getprotobynumber Searches the protocols database until a matching protocol number is found or until EOF is encountered.
getprotoent Gets a protocol database entry from the protocols database file.
getservbyname Gets information on the named service from the network services database.
getservbyport Gets information on the named port from the network services database.
getservent Gets a services file entry from the network services database file.
hostalias Searches for host aliases associated with a name.
htonl Converts longwords from network to host byte order.
htons Converts short integers from network to host byte order.
inet_addr Converts Internet addresses in text form into numeric Internet addresses.
inet_lnaof Returns the local network address portion of an Internet address.
inet_makeaddr Returns an Internet address given a network address and a local address on that network.
inet_netof Returns the Internet network address portion of an Internet address.
inet_network Converts a null-terminated text string representing an Internet network address into a network address in network byte order.
inet_ntoa Converts an Internet address into an ASCIZ (null-terminated) string.
ntohl Converts longwords from host to network byte order.
ntohs Converts short integers from host to network byte order.
sethostent Opens, rewinds, and closes the network host database file.
setnetent Opens, rewinds, and closes the networks database file.
setprotoent Opens, rewinds, and closes the protocols database file.
setservent Opens, rewinds, and closes the network services database file.
socket_fd Returns the socket descriptor associated with a Socket Device Channel for direct use with the Compaq C RTL.
vaxc$get_sdc Returns the socket device's OpenVMS I/O channel associated with a socket descriptor. vaxc$get_sdc and decc$get_sdc are synonyms for the same routine.


accept

Accepts a connection on a socket.

Format

#include <socket.h>

int accept (int s, struct sockaddr *addr, int *addrlen);

(_DECC_V4_SOURCE) int accept (int s, struct sockaddr *addr, size_t *addrlen);

(NOT _DECC_V4_SOURCE)

Routine Variants This socket routine has a variant named __bsd44_accept . Enabled by defining _sockaddr_len , this variant implements 4.4BSD-compatible semantics. See Section A.7 for more information.

Arguments

s

A socket descriptor that has been returned by socket , subsequently bound to an address with bind , and that is listening for connections after a listen .

addr

A result parameter that is filled in with the address of the connecting entity, as known to the communications layer. The exact format of the structure to which the address parameter points is determined by the domain in which the communication is occurring. This version of Compaq C supports only the Internet domain (AF_INET).

addrlen

A value-result parameter; it should initially contain the size of the structure pointed to by addr. On return it will contain the actual length, in bytes, of the structure that has been filled in by the communication layer. See <socket.h> for a description of the sockaddr structure.

Description

This routine completes the first connection on the queue of pending connections, creates a new socket with the same properties as s, and allocates and returns a new descriptor for the socket. If no pending connections are present on the queue, and the socket is not marked as nonblocking, accept blocks the caller until a connection request is present. If the socket is marked nonblocking by using a setsockopt call and no pending connections are present on the queue, accept returns an error. The accepted socket may not be used to accept connections. The original socket s remains open (listening) for other connection requests. This call is used with connection-based socket types, currently with SOCK_STREAM.

It is possible to select a socket for the purposes of performing an accept by selecting it for read.

See also bind , connect , listen , select , and socket in this section.


Return Values

x A nonnegative integer that is a descriptor for the accepted socket.
--1 Indicates an error; errno is set to one of the following:
  • EBADF -- The socket descriptor is invalid.
  • ENOTSOCK -- The socket descriptor references a file, not a socket.
  • EOPNOTSUPP -- The reference socket is not of type SOCK_STREAM.
  • EFAULT -- The addr parameter is not in a writable part of the user address space.
  • EWOULDBLOCK -- The socket is marked nonblocking and no connections are present to be accepted.

bind

Binds a name to a socket.

Format

#include <socket.h>

int bind (int s, struct sockaddr *name, int namelen);

(_DECC_V4_SOURCE) int bind (int s, const struct sockaddr *name, size_t namelen);

(NOT _DECC_V4_SOURCE)

Routine Variants This socket routine has a variant named __bsd44_bind . Enabled by defining _sockaddr_len , this variant implements 4.4BSD-compatible semantics. See Section A.7 for more information.

Arguments

s

A socket descriptor that has been created with socket .

name

Address of a structure used to assign a name to the socket in the format specific to the family (AF_INET) socket address. See <socket.h> for a description of the sockaddr structure.

namelen

The size, in bytes, of the structure pointed to by name.

Description

This routine assigns a name to an unnamed socket. When a socket is created with socket it exists in a name space (address family) but has no name assigned. The bind routine requests that a name be assigned to the socket.

See also connect , getsockname , listen , and socket in this appendix.


Return Values

0 Indicates success.
--1 Indicates an error; errno is set to one of the following values:
  • EBADF -- The socket descriptor is invalid.
  • ENOTSOCK -- The socket descriptor references a file, not a socket.
  • EADDRNOTAVAIL -- specified address is not available from the local machine.
  • EADDRINUSE -- The specified Internet address and ports are already in use.
  • EINVAL -- The socket is already bound to an address.
  • EACCESS -- The requested address is protected, and the current user has inadequate permission to access it.
  • EFAULT -- The name parameter is not a valid part of the user address space.

close

Closes a connection and deletes a socket descriptor.

Format

#include <unixio.h>

int close (s);


Argument

s

A socket descriptor.

Description

This routine deletes a descriptor from the per-process object reference table. If this is the last reference to the underlying object, then it will be deactivated.

See also accept , socket , and write in this section.


Return Values

0 Indicates success.
--1 Indicates an error; errno is set to EBADF (The socket descriptor is invalid.)

connect

Initiates a connection on a socket.

Format

#include <socket.h>

int connect (int s, struct sockaddr *name, int namelen);

(_DECC_V4_SOURCE) int connect (int s, const struct sockaddr *name, size_t namelen);

(NOT _DECC_V4_SOURCE)

Routine Variants This socket routine has a variant named __bsd44_connect . Enabled by defining _sockaddr_len , this variant implements 4.4BSD-compatible semantics. See Section A.7 for more information.

Arguments

s

A socket descriptor that has been created with socket .

name

The address of a structure that specifies the name of the remote socket in the format specific to the address family (AF_INET).

namelen

The size, in bytes, of the structure pointed to by name.

Description

If s is a socket descriptor of type SOCK_DGRAM, then this call permanently specifies the peer to which data is to be sent. If it is of type SOCK_STREAM, then this call attempts to make a connection to another socket.

Each communications space interprets the name parameter in its own way. This argument specifies the socket to which the socket specified in s is to be connected.

See also accept , select , socket , getsockname , and shutdown in this appendix.


Return Values

0 Indicates success.
--1 Indicates an error; errno is set to one of the following:
  • EBADF -- The socket descriptor is invalid.
  • ENOTSOCK -- The socket descriptor references a file, not a socket.
  • EADDRNOTAVAIL -- specified address is not available from the local machine.
  • EAFNOSUPPORT -- Address in the specified address family cannot be used with this socket.
  • EISCONN -- The socket is already connected.
  • ETIMEOUT -- Connection establishment timed out without establishing a connection.
  • ECONNREFUSED -- The attempt to connect was forcefully rejected.
  • ENETUNREACH -- The network is not reachable from this host.
  • EADDRINUSE -- The specified Internet address and ports are already in use.
  • EFAULT -- The name parameter is not a valid part of the user address space.
  • EWOULDBLOCK -- The socket is nonblocking and the connection cannot be completed immediately. It is possible to select the socket while it is connecting by selecting it for writing.

decc$get_sdc

Returns the Socket Device Channel (SDC) associated with a socket descriptor for direct use with the TCP/IP Services for OpenVMS product.

Format

#include <socket.h>

short int decc$get_sdc (int s);


Argument

s

A socket descriptor.

Description

This routine returns the SDC associated with a socket. C socket descriptors are normally used either as file descriptors or with one of the routines that take an explicit socket descriptor as its argument. C sockets are implemented using TCP/IP Services for OpenVMS Socket Device Channels. This routine returns the SDC used by a given socket descriptor so that you can use the TCP/IP Services for OpenVMS's facilities directly by means of various I/O system services ($QIO).

Return Values

0 Indicates that s is not an open socket descriptor.
x The SDC number.

endhostent

Closes host database file.

Format

#include <netdb.h>

void endhostent (void);


Description

The endhostent routine closes the network host database file, previously opened with the gethostbyaddr or gethostbyname routine.

See also gethostbyaddr , and gethostbyname in this section.


Errors

  If the endhostent routine does not exist in your TCP/IP library, then errno is set to ENOSYS.

endnetent

Closes the networks database file.

Format

#include <netdb.h>

void endnetent (void);


Description

The endentent routine closes the networks database file, previously opened with the getnetent , setnetent , getnetbyaddr or getnetbyname routine.

See also getnetent , getnetbyaddr , getnetbyname , and setnetent in this section.


Errors

  If the endnetent routine does not exist in your TCP/IP library, then errno is set to ENOSYS.

endprotoent

Closes the protocols database file.

Format

#include <netdb.h>

void endprotoent (void);


Description

The endprotoent routine closes the network protocols database file, previously opened with the getprotoent , getprotobyname , or getprotobynumber routine.

See also getprotobyname , getprotoent and getprotobynumber in this section.


Errors

  If the endprotoent routine does not exist in your TCP/IP library, then errno is set to ENOSYS.


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