Manpages - netdb.h.0p

The <netdb.h> header shall define the addrinfo structure, which shall include at least the following members:

    int               ai_flags      Input flags.
    int               ai_family     Address family of socket.
    int               ai_socktype   Socket type.
    int               ai_protocol   Protocol of socket.
    socklen_t         ai_addrlen    Length of socket address.
    struct sockaddr  *ai_addr       Socket address of socket.
    char             *ai_canonname  Canonical name of service location.
    struct addrinfo  *ai_next       Pointer to next in list.

The <netdb.h> header shall define the following symbolic constants that evaluate to bitwise-distinct integer constants for use in the flags field of the addrinfo structure:

AI_PASSIVE

Socket address is intended for /bind/().

AI_CANONNAME

Request for canonical name.

AI_NUMERICHOST

Return numeric host address as name.

AI_NUMERICSERV

Inhibit service name resolution.

AI_V4MAPPED

If no IPv6 addresses are found, query for IPv4 addresses and return them to the caller as IPv4-mapped IPv6 addresses.

AI_ALL

Query for both IPv4 and IPv6 addresses.

AI_ADDRCONFIG

Query for IPv4 addresses only when an IPv4 address is configured; query for IPv6 addresses only when an IPv6 address is configured.

The <netdb.h> header shall define the following symbolic constants that evaluate to bitwise-distinct integer constants for use in the flags argument to /getnameinfo/():

NI_NOFQDN

Only the nodename portion of the FQDN is returned for local hosts.

NI_NUMERICHOST

The numeric form of the node’s address is returned instead of its name.

NI_NAMEREQD

Return an error if the node’s name cannot be located in the database.

NI_NUMERICSERV

The numeric form of the service address is returned instead of its name.

NI_NUMERICSCOPE

For IPv6 addresses, the numeric form of the scope identifier is returned instead of its name.

NI_DGRAM

Indicates that the service is a datagram service (SOCK_DGRAM).

The <netdb.h> header shall define the following symbolic constants for use as error values for /getaddrinfo/() and /getnameinfo/(). The values shall be suitable for use in #if preprocessing directives.

EAI_AGAIN

The name could not be resolved at this time. Future attempts may succeed.

EAI_BADFLAGS

The flags had an invalid value.

EAI_FAIL

A non-recoverable error occurred.

EAI_FAMILY

The address family was not recognized or the address length was invalid for the specified family.

EAI_MEMORY

There was a memory allocation failure.

EAI_NONAME

The name does not resolve for the supplied parameters.

NI_NAMEREQD is set and the host’s name cannot be located, or both nodename and servname were null.

EAI_SERVICE

The service passed was not recognized for the specified socket type.

EAI_SOCKTYPE

The intended socket type was not recognized.

EAI_SYSTEM

A system error occurred. The error code can be found in errno.

EAI_OVERFLOW

An argument buffer overflowed.

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

    void              endhostent(void);
    void              endnetent(void);
    void              endprotoent(void);
    void              endservent(void);
    void              freeaddrinfo(struct addrinfo *);
    const char       *gai_strerror(int);
    int               getaddrinfo(const char *restrict, const char *restrict,
                          const struct addrinfo *restrict,
                          struct addrinfo **restrict);
    struct hostent   *gethostent(void);
    int               getnameinfo(const struct sockaddr *restrict, socklen_t,
                          char *restrict, socklen_t, char *restrict,
                          socklen_t, int);
    struct netent    *getnetbyaddr(uint32_t, int);
    struct netent    *getnetbyname(const char *);
    struct netent    *getnetent(void);
    struct protoent  *getprotobyname(const char *);
    struct protoent  *getprotobynumber(int);
    struct protoent  *getprotoent(void);
    struct servent   *getservbyname(const char *, const char *);
    struct servent   *getservbyport(int, const char *);
    struct servent   *getservent(void);
    void              sethostent(int);
    void              setnetent(int);
    void              setprotoent(int);
    void              setservent(int);

The <netdb.h> header shall define the socklen_t type through typedef, as described in <sys/socket.h>.

Inclusion of the <netdb.h> header may also make visible all symbols from <netinet/in.h>, <sys/socket.h>, and <inttypes.h>.

The following sections are informative.