NAME
getprotoent,
getprotoent_r,
getprotobynumber,
getprotobynumber_r,
getprotobyname,
getprotobyname_r,
setprotoent, endprotoent
— get protocol entry
LIBRARY
library “libc”
SYNOPSIS
#include
<netdb.h>
struct protoent *
getprotoent(void);
int
getprotoent_r(struct
protoent *, char *,
size_t,
struct protoent **);
struct protoent *
getprotobyname(const
char *name);
int
getprotobyname_r(const
char *, struct protoent
*, char *,
size_t,
struct protoent **);
struct protoent *
getprotobynumber(int
proto);
int
getprotobynumber_r(int,
struct protoent *,
char *,
size_t,
struct protoent **);
void
setprotoent(int
stayopen);
void
endprotoent(void);
DESCRIPTION
Thegetprotoent(),
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 alternate 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.
The
getprotoent_r(),
getprotobynumber_r(),
and
getprotobyname_r()
functions are reentrant versions of the above functions that take a pointer
to a protoent 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. These functions also take
a pointer to another protoent structure which is used
to store the results of the database lookup.
RETURN VALUES
The getprotoent(),
getprotobynumber(), and
getprotobyname() functions return a pointer to a
protoent structure on success or a null pointer if
end-of-file is reached or an error occurs.
The getprotoent_r(),
getprotobynumber_r(), and
getprotobyname_r() functions return 0 on success or
-1 if end-of-file is reached or an error occurs.
FILES
- /etc/protocols
SEE ALSO
STANDARDS
The getprotoent(),
getprotobynumber(),
getprotobyname(),
setprotoent(), and
endprotoent() functions conform to
IEEE Std 1003.1-2004 (“POSIX.1”).
The getprotoent_r(),
getprotobynumber_r(), and
getprotobyname_r() functions are not currently
standardized.
HISTORY
The getprotoent(),
getprotobynumber(),
getprotobyname(),
setprotoent(), and
endprotoent() functions appeared in
4.2BSD.
The getprotoent_r(),
getprotobynumber_r(), and
getprotobyname_r() functions appeared in
DragonFly 2.1.
BUGS
These functions use a thread-specific 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.