NAME
getprotoent,
getprotobynumber,
getprotobyname,
setprotoent,
endprotoent —
get protocol
entry
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <netdb.h>
struct protoent *
getprotoent();
struct protoent *
getprotobyname(
const
char *name);
struct protoent *
getprotobynumber(
int
proto);
void
setprotoent(
int
stayopen);
void
endprotoent(
void);
DESCRIPTION
The
getprotoent(),
getprotobyname(), and
getprotobynumber() functions each return a pointer to an
object with the following structure containing the broken-out fields of a line
in the network protocol data base,
/etc/protocols.
struct protoent {
char *p_name; /* official name of protocol */
char **p_aliases; /* alias list */
int p_proto; /* protocol number */
};
The members of this structure are:
-
-
- p_name
- The official name of the protocol.
-
-
- p_aliases
- A zero terminated list of alternative names for the
protocol.
-
-
- p_proto
- The protocol number.
The
getprotoent() function reads the next line of the file,
opening the file if necessary.
The
setprotoent() 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
getprotobyname() or
getprotobynumber().
The
endprotoent() function closes the file.
The
getprotobyname() function and
getprotobynumber() sequentially search from the beginning of
the file until a matching protocol name or protocol number is found, or until
EOF
is encountered.
RETURN VALUES
Upon success,
getprotoent(),
getprotobyname(), and
getprotobynumber()
return a pointer to the
protoent structure as described
above. A
NULL
pointer is returned on
EOF
or error.
FILES
- /etc/protocols
-
SEE ALSO
protocols(5)
HISTORY
The
getprotoent(),
getprotobynumber(),
getprotobyname(),
setprotoent(), and
endprotoent() functions appeared in
4.2BSD.
BUGS
These functions use a static data space; if the data is needed for future use,
it should be copied before any subsequent calls overwrite it. Only the
Internet protocols are currently understood.