+\r
+function have_ipv6_connectivity:boolean;\r
+var\r
+ l:tbiniplist;\r
+ a:integer;\r
+ ip:tbinip;\r
+ ipmask_global,ipmask_6to4,ipmask_teredo:tbinip;\r
+\r
+function ip_is_suitable_v6:boolean;\r
+begin\r
+ result := false;\r
+ if (ip.family <> AF_INET6) then exit;\r
+ if not comparebinipmask(ip,ipmask_global,3) then exit;\r
+ if comparebinipmask(ip,ipmask_teredo,32) then exit;\r
+ if comparebinipmask(ip,ipmask_6to4,16) then exit;\r
+ result := true;\r
+end;\r
+\r
+begin\r
+ result := false;\r
+\r
+ ipstrtobin('2000::',ipmask_global);\r
+ ipstrtobin('2001::',ipmask_teredo);\r
+ ipstrtobin('2002::',ipmask_6to4);\r
+\r
+ {$ifdef mswindows}\r
+ //better way on windows to check for ipv6 that works (returns no ipv6) if a v6 IP is assigned, but there is no connectivity\r
+ try\r
+ ip := getlocalipforip(ipstrtobinf(v6_check_ip));\r
+ if ip_is_suitable_v6 then result := true;\r
+ except\r
+ end;\r
+ {$else} {unix}\r
+\r
+ l := getv6localips;\r
+ if biniplist_getcount(l) = 0 then exit;\r
+\r
+ {if there is any v6 IP which is globally routable and not 6to4 and not teredo, prefer v6}\r
+ for a := biniplist_getcount(l)-1 downto 0 do begin\r
+ ip := biniplist_get(l,a);\r
+ if not ip_is_suitable_v6 then continue;\r
+ result := true;\r
+ exit;\r
+ end;\r
+ {$endif}\r
+end;\r
+\r
+\r