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1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen<HTML
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><HEAD
dfdebb1b925332352966804303b2516a6506a429Zbigniew Jędrzejewski-Szmek><TITLE
dfdebb1b925332352966804303b2516a6506a429Zbigniew Jędrzejewski-Szmek>lwres_getaddrinfo</TITLE
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><META
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1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><H1
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><A
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenNAME="AEN1"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>lwres_getaddrinfo</A
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></H1
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><DIV
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="REFNAMEDIV"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><A
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenNAME="AEN8"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></A
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><H2
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>Name</H2
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>lwres_getaddrinfo, lwres_freeaddrinfo&nbsp;--&nbsp;socket address structure to host and service name</DIV
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><DIV
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="REFSYNOPSISDIV"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><A
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenNAME="AEN12"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></A
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><H2
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>Synopsis</H2
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><DIV
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="FUNCSYNOPSIS"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><A
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenNAME="AEN13"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></A
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><PRE
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="FUNCSYNOPSISINFO"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>#include &lt;lwres/netdb.h&gt;</PRE
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><CODE
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><CODE
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="FUNCDEF"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>int
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynenlwres_getaddrinfo</CODE
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>(const char *hostname, const char *servname, const struct addrinfo *hints, struct addrinfo **res);</CODE
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><CODE
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><CODE
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="FUNCDEF"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>void
dfdebb1b925332352966804303b2516a6506a429Zbigniew Jędrzejewski-Szmeklwres_freeaddrinfo</CODE
dfdebb1b925332352966804303b2516a6506a429Zbigniew Jędrzejewski-Szmek>(struct addrinfo *ai);</CODE
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></DIV
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>If the operating system does not provide a
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen<SPAN
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="TYPE"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>struct addrinfo</SPAN
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>,
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynenthe following structure is used:
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen<PRE
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="PROGRAMLISTING"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>struct addrinfo {
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen int ai_flags; /* AI_PASSIVE, AI_CANONNAME */
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen int ai_family; /* PF_xxx */
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen int ai_socktype; /* SOCK_xxx */
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen int ai_protocol; /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen size_t ai_addrlen; /* length of ai_addr */
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen char *ai_canonname; /* canonical name for hostname */
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen struct sockaddr *ai_addr; /* binary address */
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen struct addrinfo *ai_next; /* next structure in linked list */
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen};</PRE
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></DIV
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><DIV
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenCLASS="REFSECT1"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><A
1bc64d77352010f6951e7cccf77be99301e9664cMarko MyllynenNAME="AEN29"
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen></A
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><H2
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen>DESCRIPTION</H2
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><P
1bc64d77352010f6951e7cccf77be99301e9664cMarko Myllynen><TT
CLASS="FUNCTION"
>lwres_getaddrinfo()</TT
>
is used to get a list of IP addresses and port numbers for host
<TT
CLASS="PARAMETER"
><I
>hostname</I
></TT
>
and service
<TT
CLASS="PARAMETER"
><I
>servname</I
></TT
>.
The function is the lightweight resolver's implementation of
<TT
CLASS="FUNCTION"
>getaddrinfo()</TT
>
as defined in RFC2133.
<TT
CLASS="PARAMETER"
><I
>hostname</I
></TT
>
and
<TT
CLASS="PARAMETER"
><I
>servname</I
></TT
>
are pointers to null-terminated
strings or
<SPAN
CLASS="TYPE"
>NULL</SPAN
>.
<TT
CLASS="PARAMETER"
><I
>hostname</I
></TT
>
is either a host name or a numeric host address string: a dotted decimal
IPv4 address or an IPv6 address.
<TT
CLASS="PARAMETER"
><I
>servname</I
></TT
>
is either a decimal port number or a service name as listed in
<TT
CLASS="FILENAME"
>/etc/services</TT
>.</P
><P
><TT
CLASS="PARAMETER"
><I
>hints</I
></TT
>
is an optional pointer to a
<SPAN
CLASS="TYPE"
>struct addrinfo</SPAN
>.
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
<TT
CLASS="PARAMETER"
><I
>*hints</I
></TT
>:
<P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="CONSTANT"
>ai_family</TT
></DT
><DD
><P
>The protocol family that should be used.
When
<TT
CLASS="CONSTANT"
>ai_family</TT
>
is set to
<SPAN
CLASS="TYPE"
>PF_UNSPEC</SPAN
>,
it means the caller will accept any protocol family supported by the
operating system.</P
></DD
><DT
><TT
CLASS="CONSTANT"
>ai_socktype</TT
></DT
><DD
><P
>denotes the type of socket &mdash;
<SPAN
CLASS="TYPE"
>SOCK_STREAM</SPAN
>,
<SPAN
CLASS="TYPE"
>SOCK_DGRAM</SPAN
>
or
<SPAN
CLASS="TYPE"
>SOCK_RAW</SPAN
>
&mdash; that is wanted.
When
<TT
CLASS="CONSTANT"
>ai_socktype</TT
>
is zero the caller will accept any socket type.</P
></DD
><DT
><TT
CLASS="CONSTANT"
>ai_protocol</TT
></DT
><DD
><P
>indicates which transport protocol is wanted: IPPROTO_UDP or
IPPROTO_TCP.
If
<TT
CLASS="CONSTANT"
>ai_protocol</TT
>
is zero the caller will accept any protocol.</P
></DD
><DT
><TT
CLASS="CONSTANT"
>ai_flags</TT
></DT
><DD
><P
>Flag bits.
If the
<SPAN
CLASS="TYPE"
>AI_CANONNAME</SPAN
>
bit is set, a successful call to
<TT
CLASS="FUNCTION"
>lwres_getaddrinfo()</TT
>
will return a null-terminated string containing the canonical name
of the specified hostname in
<TT
CLASS="CONSTANT"
>ai_canonname</TT
>
of the first
<SPAN
CLASS="TYPE"
>addrinfo</SPAN
>
structure returned.
Setting the
<SPAN
CLASS="TYPE"
>AI_PASSIVE</SPAN
>
bit indicates that the returned socket address structure is intended
for used in a call to
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>bind</SPAN
>(2)</SPAN
>.
In this case, if the hostname argument is a
<SPAN
CLASS="TYPE"
>NULL</SPAN
>
pointer, then the IP address portion of the socket
address structure will be set to
<SPAN
CLASS="TYPE"
>INADDR_ANY</SPAN
>
for an IPv4 address or
<SPAN
CLASS="TYPE"
>IN6ADDR_ANY_INIT</SPAN
>
for an IPv6 address.</P
><P
>When
<TT
CLASS="CONSTANT"
>ai_flags</TT
>
does not set the
<SPAN
CLASS="TYPE"
>AI_PASSIVE</SPAN
>
bit, the returned socket address structure will be ready
for use in a call to
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>connect</SPAN
>(2)</SPAN
>
for a connection-oriented protocol or
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>connect</SPAN
>(2)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>sendto</SPAN
>(2)</SPAN
>,
or
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>sendmsg</SPAN
>(2)</SPAN
>
if a connectionless protocol was chosen.
The IP address portion of the socket address structure will be
set to the loopback address if
<TT
CLASS="PARAMETER"
><I
>hostname</I
></TT
>
is a
<SPAN
CLASS="TYPE"
>NULL</SPAN
>
pointer and
<SPAN
CLASS="TYPE"
>AI_PASSIVE</SPAN
>
is not set in
<TT
CLASS="CONSTANT"
>ai_flags</TT
>.</P
><P
>If
<TT
CLASS="CONSTANT"
>ai_flags</TT
>
is set to
<SPAN
CLASS="TYPE"
>AI_NUMERICHOST</SPAN
>
it indicates that
<TT
CLASS="PARAMETER"
><I
>hostname</I
></TT
>
should be treated as a numeric string defining an IPv4 or IPv6 address
and no name resolution should be attempted.</P
></DD
></DL
></DIV
></P
><P
>All other elements of the <SPAN
CLASS="TYPE"
>struct addrinfo</SPAN
> passed
via <TT
CLASS="PARAMETER"
><I
>hints</I
></TT
> must be zero.</P
><P
>A <TT
CLASS="PARAMETER"
><I
>hints</I
></TT
> of <SPAN
CLASS="TYPE"
>NULL</SPAN
> is treated as if
the caller provided a <SPAN
CLASS="TYPE"
>struct addrinfo</SPAN
> initialized to zero
with <TT
CLASS="CONSTANT"
>ai_family</TT
>set to
<TT
CLASS="CONSTANT"
>PF_UNSPEC</TT
>.</P
><P
>After a successful call to
<TT
CLASS="FUNCTION"
>lwres_getaddrinfo()</TT
>,
<TT
CLASS="PARAMETER"
><I
>*res</I
></TT
>
is a pointer to a linked list of one or more
<SPAN
CLASS="TYPE"
>addrinfo</SPAN
>
structures.
Each
<SPAN
CLASS="TYPE"
>struct addrinfo</SPAN
>
in this list cn be processed by following
the
<TT
CLASS="CONSTANT"
>ai_next</TT
>
pointer, until a
<SPAN
CLASS="TYPE"
>NULL</SPAN
>
pointer is encountered.
The three members
<TT
CLASS="CONSTANT"
>ai_family</TT
>,
<TT
CLASS="CONSTANT"
>ai_socktype</TT
>,
and
<TT
CLASS="CONSTANT"
>ai_protocol</TT
>
in each
returned
<SPAN
CLASS="TYPE"
>addrinfo</SPAN
>
structure contain the corresponding arguments for a call to
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>socket</SPAN
>(2)</SPAN
>.
For each
<SPAN
CLASS="TYPE"
>addrinfo</SPAN
>
structure in the list, the
<TT
CLASS="CONSTANT"
>ai_addr</TT
>
member points to a filled-in socket address structure of length
<TT
CLASS="CONSTANT"
>ai_addrlen</TT
>.</P
><P
>All of the information returned by
<TT
CLASS="FUNCTION"
>lwres_getaddrinfo()</TT
>
is dynamically allocated: the addrinfo structures, and the socket
address structures and canonical host name strings pointed to by the
<TT
CLASS="CONSTANT"
>addrinfo</TT
>structures.
Memory allocated for the dynamically allocated structures created by
a successful call to
<TT
CLASS="FUNCTION"
>lwres_getaddrinfo()</TT
>
is released by
<TT
CLASS="FUNCTION"
>lwres_freeaddrinfo()</TT
>.
<TT
CLASS="PARAMETER"
><I
>ai</I
></TT
>
is a pointer to a
<SPAN
CLASS="TYPE"
>struct addrinfo</SPAN
>
created by a call to
<TT
CLASS="FUNCTION"
>lwres_getaddrinfo()</TT
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN142"
></A
><H2
>RETURN VALUES</H2
><P
><TT
CLASS="FUNCTION"
>lwres_getaddrinfo()</TT
>
returns zero on success or one of the error codes listed in
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>gai_strerror</SPAN
>(3)</SPAN
>
if an error occurs.
If both
<TT
CLASS="PARAMETER"
><I
>hostname</I
></TT
>
and
<TT
CLASS="PARAMETER"
><I
>servname</I
></TT
>
are
<SPAN
CLASS="TYPE"
>NULL</SPAN
>
<TT
CLASS="FUNCTION"
>lwres_getaddrinfo()</TT
>
returns
<SPAN
CLASS="ERRORCODE"
>EAI_NONAME</SPAN
>.&#13;</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN154"
></A
><H2
>SEE ALSO</H2
><P
><SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres</SPAN
>(3)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres_getaddrinfo</SPAN
>(3)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres_freeaddrinfo</SPAN
>(3)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres_gai_strerror</SPAN
>(3)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>RFC2133</SPAN
></SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>getservbyname</SPAN
>(3)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>bind</SPAN
>(2)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>connect</SPAN
>(2)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>sendto</SPAN
>(2)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>sendmsg</SPAN
>(2)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>socket</SPAN
>(2)</SPAN
>.</P
></DIV
></BODY
></HTML
>