GETSERVENT(3) BSD Library Functions Manual GETSERVENT(3)NAME
getservent, getservbyport, getservbyname, setservent, endservent — get
service entry
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <netdb.h>
struct servent *
getservent();
struct servent *
getservbyname(const char *name, const char *proto);
struct servent *
getservbyport(int port, const char *proto);
void
setservent(int stayopen);
void
endservent(void);
DESCRIPTION
The getservent(), getservbyname(), and getservbyport() functions each
return a pointer to an object with the following structure containing the
broken-out fields of a line in the network services data base,
/etc/services.
struct servent {
char *s_name; /* official name of service */
char **s_aliases; /* alias list */
int s_port; /* port service resides at */
char *s_proto; /* protocol to use */
};
The members of this structure are:
s_name The official name of the service.
s_aliases A zero terminated list of alternate names for the service.
s_port The port number at which the service resides. Port numbers
are returned in network byte order.
s_proto The name of the protocol to use when contacting the service.
The getservent() function reads the next line of the file, opening the
file if necessary.
The setservent() function opens and rewinds the file. If the stayopen
flag is non-zero, the net data base will not be closed after each call to
getservbyname() or getservbyport().
The endservent() function closes the file.
The getservbyname() and getservbyport() functions sequentially search
from the beginning of the file until a matching protocol name or port
number (which must be specified in network byte order) is found, or until
EOF is encountered. If a protocol name is also supplied (non- NULL),
searches must also match the protocol.
FILES
/etc/services
DIAGNOSTICS
Null pointer (0) returned on EOF or error.
SEE ALSOgetprotoent(3), services(5)HISTORY
The getservent(), getservbyport(), getservbyname(), setservent(), and
endservent() functions appeared in 4.2BSD.
BUGS
These functions use a thread-specific data storage; if the data is needed
for future use, it should be copied before any subsequent calls overwrite
it. Expecting port numbers to fit in a 32 bit quantity is probably
naive.
BSD July 9, 1995 BSD
