.TH dns_ip6 3 .SH NAME dns_ip6 \- look up IPv4 addresses .SH SYNTAX .B #include int \fBdns_ip6\fP(stralloc* \fIout\fR,stralloc* \fIfqdn\fR); .SH DESCRIPTION dns_ip6 looks up 16-byte IPv6 addresses for the fully-qualified domain name in \fIfqdn\fR. It puts the concatenation of the IPv6 addresses into \fIout\fR and returns 0. If the domain does not exist in DNS, or has no IP addresses, \fIout\fR will be empty. dns_ip6 also looks up 4-byte IPv4 addresses and converts them into IPv4-mapped IPv6 addresses (::ffff:1.2.3.4) to provide easy backwards compatibility for IPv6 applications. If dns_ip6 has trouble with the DNS lookup or runs out of memory, it returns -1, setting errno appropriately. It may or may not change \fIout\fR. If \fIfqdn\fR is an IPv6 address, dns_ip6 puts that IP address into \fIout\fR without checking DNS. IPv4 addresses are also used directly without DNS lookup. .SH "SEE ALSO" dns_ip6_packet(3), dns_ip4(3), dns_name6(3)