diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/ipcalc.lua | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/ipcalc.lua b/lib/ipcalc.lua new file mode 100644 index 0000000..fb05561 --- /dev/null +++ b/lib/ipcalc.lua @@ -0,0 +1,55 @@ + +module (..., package.seeall) +require("bit") + +function iptoint(str) + -- TODO: support "a.", "a.b.", "a.b.c." + local a,b,c,d = string.match(str, "(%d+).(%d+).(%d+).(%d+)") + if a and b and c and d then + return bit.lshift(a, 24) + bit.lshift(b, 16) + bit.lshift(c, 8) + d + end + return nil +end + +function nettoint(net, mask) + if mask == nil then + mask = string.match(net, "/(.*)") + if mask == nil then + -- no mask provied at all + return iptoint(net) + end + net = string.gsub(net, "/.*", "") + end + + local n = tonumber(mask) + if n == nil then + -- mask is a.b.c.d style + return iptoint(net), iptoint(mask) + end + + -- mask is /24 style + if n > 32 then + return nil + end + return iptoint(net), bit.band(bit.lshift(0xfffffffff, 32 - n), 0xffffffff) +end + + +-- same_subnet - check if address is in net/mask +-- synopsis: +-- same_subnet(addr, net[/mask][, mask]) +-- example: +-- same_subnet("10.0.0.1", "10.0.0.0/24") +-- same_subnet("10.0.0.1", "10.0.0.0", "24") +-- same_subnet("10.0.0.1", "10.0.0.0/255.255.255.0") +-- same_subnet("10.0.0.1", "10.0.0.0", "255.255.255.0") + +function same_subnet(addr, net, mask) + local a = iptoint(addr) + local n, m = nettoint(net, mask) + if a and n and m then + return bit.band(a, m) == bit.band(n, m) + end + return false +end + |