GETPROTOENT(3) | Library Functions Manual | GETPROTOENT(3)

# 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.

July 15, 2011 | NetBSD 9.0