struct netent *getnetbyaddr(uint32_t net, int type);
struct netent *getnetbyname(const char *name);
struct netent *getnetent(void);
void setnetent(int stayopen);
These functions shall retrieve information about networks. This information is considered to be stored in a database that can be accessed sequentially or randomly. The implementation of this database is unspecified.
The setnetent() function shall open and rewind the database. If the stayopen argument is non-zero, the connection to the net database shall not be closed after each call to getnetent() (either directly, or indirectly through one of the other getnet*() functions), and the implementation may maintain an open file descriptor to the database.
The getnetent() function shall read the next entry of the database, opening and closing a connection to the database as necessary.
The getnetbyaddr() function shall search the database from the beginning, and find the first entry for which the address family specified by type matches the n_addrtype member and the network number net matches the n_net member, opening and closing a connection to the database as necessary. The net argument shall be the network number in host byte order.
The getnetbyname() function shall search the database from the beginning and find the first entry for which the network name specified by name matches the n_name member, opening and closing a connection to the database as necessary.
The getnetbyaddr(), getnetbyname(), and getnetent() functions shall each return a pointer to a netent structure, the members of which shall contain the fields of an entry in the network database.
The endnetent() function shall close the database, releasing any open file descriptor.
These functions need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.
Upon successful completion, getnetbyaddr(), getnetbyname(), and getnetent() shall return a pointer to a netent 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 shall be returned.
No errors are defined.
The following sections are informative.
The getnetbyaddr(), getnetbyname(), and getnetent() functions may return pointers to static data, which may be overwritten by subsequent calls to any of these functions.
The Base Definitions volume of IEEE Std 1003.1-2001, <netdb.h>