GETPROTOENT(3)

NAME
getprotoent, getprotoent_r, getprotobynumber, getprotobynumber_r, getprotobyname, getprotobyname_r, setprotoent, endprotoent - get protocol entry

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
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.

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
protocols(5)

STANDARDS
The getprotoent(), getprotobynumber(), getprotobyname(), setprotoent(), and endprotoent() functions conform to p1003.1-2004.

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.