The getprotobyname(), getprotobynumber() and getprotoent(), functions each return a pointer to a protoent structure, the members of which contain the fields of an entry in the network protocol database.

The getprotoent() function reads the next entry of the database, opening a connection to the database if necessary.

The getprotobyname() function searches the database from the beginning and finds the first entry for which the protocol name specified by name matches the p_name member, opening a connection to the database if necessary.

The getprotobynumber() function searches the database from the beginning and finds the first entry for which the protocol number specified by number matches the p_proto member, opening a connection to the database if necessary.

The setprotoent() function opens a connection to the database, and sets the next entry to the first entry. If the stayopen argument is non-zero, the connection to the network protocol database will not be closed after each call to getprotoent() (either directly, or indirectly through one of the other getproto*() functions).

The endprotoent() function closes the connection to the database.

The getprotobyname(), getprotobynumber() and getprotoent() functions may return pointers to static data, which may be overwritten by subsequent calls to any of these functions.

These functions are generally used with the Internet address family.

On successful completion, getprotobyname(), getprotobynumber() and getprotoent() functions return a pointer to a protoent structure if the requested entry was found, and a null pointer if the end of the database was reached or the requested entry was not found. Otherwise, a null pointer is returned.

No errors are defined.

See attributes(5) for descriptions of the following attributes:

attributes(5)