GETSERVENT(3) BSD Programmer's Manual GETSERVENT(3)
getservent, getservent_r, getservbyport, getservbyport_r, getservbyname,
getservbyname_r, setservent, setservent_r, endservent, endservent_r - get
service entry
#include <netdb.h>
struct servent *
getservent(void);
int
getservent_r(struct servent *servent, struct servent_data *servent_data);
struct servent *
getservbyname(const char *name, const char *proto);
int
getservbyname_r(const char *name, const char *proto,
struct servent *servent, struct servent_data *servent_data);
struct servent *
getservbyport(int port, const char *proto);
int
getservbyport_r(int port, const char *proto, struct servent *servent,
struct servent_data *servent_data);
void
setservent(int stayopen);
void
setservent_r(int stayopen, struct servent_data *servent_data);
void
endservent(void);
void
endservent_r(struct servent_data *servent_data);
The getservent(), getservbyname(), and getservbyport() functions each re-
turn a pointer to an object with the following structure containing the
broken-out fields of a line in the network services database,
/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 null-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 services database 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 (specified in network byte order) is found, or until EOF is en-
countered. If a protocol name is also supplied (non-null), searches must
also match the protocol.
The getservent_r(), getservbyport_r(), getservbyname_r(), setservent_r(),
and endservent_r() functions are reentrant versions of the above func-
tions that take a pointer to a servent_data structure which is used to
store state information. The structure must be zero-filled before it is
used and should be considered opaque for the sake of portability.
The getservent_r(), getservbyport_r(), and getservbyname_r() functions
also take a pointer to a servent structure which is used to store the
results of the database lookup.
The getservent(), getservbyport(), and getservbyname() functions return a
pointer to a servent structure on success or a null pointer if end-of-
file is reached or an error occurs.
The getservent_r(), getservbyport_r(), and getservbyname_r() functions
return 0 on success or -1 if end-of-file is reached or an error occurs.
/etc/services
getprotoent(3), services(5)
The getservent(), getservbynumber(), getservbyname(), setservent(), and
endservent() functions conform to IEEE Std 1003.1-2004 ("POSIX.1").
The getservent_r(), getservbyport_r(), getservbyname_r(), setservent_r(),
and endservent_r() functions are not currently standardized. This imple-
mentation follows the API used by HP, IBM, and Digital.
The getservent(), getservbyport(), getservbyname(), setservent(), and
endservent() functions appeared in 4.2BSD.
The getservent_r(), getservbyport_r(), getservbyname_r(), setservent_r(),
and endservent_r() functions appeared in OpenBSD 3.7.
The non-reentrant functions use static data storage; if the data is need-
ed for future use, it should be copied before any subsequent calls
overwrite it. Expecting port numbers to fit in a 32-bit quantity is prob-
ably naive.
MirBSD #10-current October 13, 2004 1