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LWRES_GETADDRINFO(3) BIND9 LWRES_GETADDRINFO(3)
NAME
lwres_getaddrinfo, lwres_freeaddrinfo - socket address structure to host and service name
SYNOPSIS
#include <lwres/netdb.h>
int lwres_getaddrinfo(const char *hostname, const char *servname,
const struct addrinfo *hints, struct addrinfo **res);
void lwres_freeaddrinfo(struct addrinfo *ai);
If the operating system does not provide a struct addrinfo, the following structure is
used:
struct addrinfo {
int ai_flags; /* AI_PASSIVE, AI_CANONNAME */
int ai_family; /* PF_xxx */
int ai_socktype; /* SOCK_xxx */
int ai_protocol; /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
size_t ai_addrlen; /* length of ai_addr */
char *ai_canonname; /* canonical name for hostname */
struct sockaddr *ai_addr; /* binary address */
struct addrinfo *ai_next; /* next structure in linked list */
};
DESCRIPTION
lwres_getaddrinfo() is used to get a list of IP addresses and port numbers for host
hostname and service servname. The function is the lightweight resolver's implementation
of getaddrinfo() as defined in RFC2133. hostname and servname are pointers to
null-terminated strings or NULL. hostname is either a host name or a numeric host address
string: a dotted decimal IPv4 address or an IPv6 address. servname is either a decimal
port number or a service name as listed in /etc/services.
hints is an optional pointer to a struct addrinfo. This structure can be used to provide
hints concerning the type of socket that the caller supports or wishes to use. The caller
can supply the following structure elements in *hints:
ai_family
The protocol family that should be used. When ai_family is set to PF_UNSPEC, it means
the caller will accept any protocol family supported by the operating system.
ai_socktype
denotes the type of socket -- SOCK_STREAM, SOCK_DGRAM or SOCK_RAW -- that is wanted.
When ai_socktype is zero the caller will accept any socket type.
ai_protocol
indicates which transport protocol is wanted: IPPROTO_UDP or IPPROTO_TCP. If
ai_protocol is zero the caller will accept any protocol.
ai_flags
Flag bits. If the AI_CANONNAME bit is set, a successful call to lwres_getaddrinfo()
will return a null-terminated string containing the canonical name of the specified
hostname in ai_canonname of the first addrinfo structure returned. Setting the
AI_PASSIVE bit indicates that the returned socket address structure is intended for
used in a call to bind(2). In this case, if the hostname argument is a NULL pointer,
then the IP address portion of the socket address structure will be set to INADDR_ANY
for an IPv4 address or IN6ADDR_ANY_INIT for an IPv6 address.
When ai_flags does not set the AI_PASSIVE bit, the returned socket address structure
will be ready for use in a call to connect(2) for a connection-oriented protocol or
connect(2), sendto(2), or sendmsg(2) if a connectionless protocol was chosen. The IP
address portion of the socket address structure will be set to the loopback address if
hostname is a NULL pointer and AI_PASSIVE is not set in ai_flags.
If ai_flags is set to AI_NUMERICHOST it indicates that hostname should be treated as a
numeric string defining an IPv4 or IPv6 address and no name resolution should be
attempted.
All other elements of the struct addrinfo passed via hints must be zero.
A hints of NULL is treated as if the caller provided a struct addrinfo initialized to zero
with ai_familyset to PF_UNSPEC.
After a successful call to lwres_getaddrinfo(), *res is a pointer to a linked list of one
or more addrinfo structures. Each struct addrinfo in this list cn be processed by
following the ai_next pointer, until a NULL pointer is encountered. The three members
ai_family, ai_socktype, and ai_protocol in each returned addrinfo structure contain the
corresponding arguments for a call to socket(2). For each addrinfo structure in the list,
the ai_addr member points to a filled-in socket address structure of length ai_addrlen.
All of the information returned by lwres_getaddrinfo() is dynamically allocated: the
addrinfo structures, and the socket address structures and canonical host name strings
pointed to by the addrinfostructures. Memory allocated for the dynamically allocated
structures created by a successful call to lwres_getaddrinfo() is released by
lwres_freeaddrinfo(). ai is a pointer to a struct addrinfo created by a call to
lwres_getaddrinfo().
RETURN VALUES
lwres_getaddrinfo() returns zero on success or one of the error codes listed in
gai_strerror(3) if an error occurs. If both hostname and servname are
NULLlwres_getaddrinfo() returns EAI_NONAME.
SEE ALSO
lwres(3), lwres_getaddrinfo(3), lwres_freeaddrinfo(3), lwres_gai_strerror(3), RFC2133(),
getservbyname(3), bind(2), connect(2), sendto(2), sendmsg(2), socket(2).
AUTHOR
Internet Systems Consortium, Inc.
COPYRIGHT
Copyright (C) 2000, 2001, 2003-2005, 2007, 2014-2016, 2018 Internet Systems Consortium,
Inc. ("ISC")
ISC 2007-06-18 LWRES_GETADDRINFO(3)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2024-04-26 06:08 @18.119.111.9 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)