NAME
getprotoent,
getprotobynumber,
getprotobyname, setprotoent,
endprotoent —
get protocol entry
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<netdb.h>
struct protoent *
getprotoent(void);
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 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.
RETURN VALUES
Null pointer (0) returned on EOF or
error.
FILES
- /etc/protocols
SEE ALSO
HISTORY
The getprotoent(),
getprotobynumber(),
getprotobyname(),
setprotoent(), and
endprotoent() functions appeared in
4.2BSD.
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.