NAME
endservent, getservbyname, getservbyport, getservent, setservent -
network services database functions
SYNOPSIS
#include <netdb.h>
void endservent(void);
struct servent *getservbyname(const char *name, const char *proto);
struct servent *getservbyport(int port, const char *proto);
struct servent *getservent(void);
void setservent(int stayopen);
DESCRIPTION
These functions shall retrieve information about network services.
This information is considered to be stored in a database that can be
accessed sequentially or randomly. The implementation of this database
is unspecified.
The setservent() function shall open a connection to the database, and
set the next entry to the first entry. If the stayopen argument is non-
zero, the net database shall not be closed after each call to the
getservent() function (either directly, or indirectly through one of
the other getserv*() functions), and the implementation may maintain an
open file descriptor for the database.
The getservent() function shall read the next entry of the database,
opening and closing a connection to the database as necessary.
The getservbyname() function shall search the database from the
beginning and find the first entry for which the service name specified
by name matches the s_name member and the protocol name specified by
proto matches the s_proto member, opening and closing a connection to
the database as necessary. If proto is a null pointer, any value of the
s_proto member shall be matched.
The getservbyport() function shall search the database from the
beginning and find the first entry for which the port specified by port
matches the s_port member and the protocol name specified by proto
matches the s_proto member, opening and closing a connection to the
database as necessary. If proto is a null pointer, any value of the
s_proto member shall be matched. The port argument shall be in network
byte order.
The getservbyname(), getservbyport(), and getservent() functions shall
each return a pointer to a servent structure, the members of which
shall contain the fields of an entry in the network services database.
The endservent() function shall close the database, releasing any open
file descriptor.
These functions need not be reentrant. A function that is not required
to be reentrant is not required to be thread-safe.
RETURN VALUE
Upon successful completion, getservbyname(), getservbyport(), and
getservent() return a pointer to a servent structure if the requested
entry was found, and a null pointer if the end of the database was
reached or the requested entry was not found. Otherwise, a null pointer
is returned.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The port argument of getservbyport() need not be compatible with the
port values of all address families.
The getservbyname(), getservbyport(), and getservent() functions may
return pointers to static data, which may be overwritten by subsequent
calls to any of these functions.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
endhostent() , endprotoent() , htonl() , inet_addr() , the Base
Definitions volume of IEEE Std 1003.1-2001, <netdb.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .