An IPv4 header, to scale · 20 bytes · one column per bit
Addresses, blocks,
and the bits
between them.
moonip reads the text forms of RFC 4291 and gives every address back in the canonical shape of RFC 5952. It works out the block an address sits in, splits blocks down, joins ranges back up, and places an address in one of the IANA special-purpose registries. Nothing here opens a socket: the two fields above are the whole job.
- families
- IPv4 · IPv6, zones included
- text
- RFC 4291 in, RFC 5952 out
- blocks
- classless, /0 to /32 and /0 to /128
- targets
- wasm · wasm-gc · js · native
fig. 1 Field widths are bit widths read off the header, not a drawing decision: four columns for a nibble, eight for an octet, thirty-two for an address. The two shaded rows are Addr; the hatched fields belong to a layer that owns them.
three types
Everything else is a function over these.
| type | width | made by | what it is |
|---|---|---|---|
| Addr | 32 · 128 | parse decode v4 v6 |
One address, plus the zone a scoped IPv6 address carries. Immutable, ordered, hashable. |
| Prefix | addr + 0…32 addr + 0…128 |
parse new |
A block. Keeps the address it was written with, so one value can stand for an interface. |
| AddrPort | addr + 16 | parse new |
One end of a conversation: four dotted fields with a port, or a bracketed IPv6 with one. |
fig. 2 The width column is the field width the value models, not a structure size.
the library, running here
Paste one.
fe80::1%eth0 · ::ffff:192.0.2.1 · 10.1.2.3 · 2001:4860:4860::8888
fig. 3 Not a mock-up: this is src/examples/browser compiled to
JavaScript and imported by the page. Every string above is the library's answer, and the bit row is
drawn from the encoded bytes.
two lines
Add it, then read a block.
fn main raise {
let block = @moonip.Prefix::parse("192.0.2.0/24")
println(block.netmask()) // 255.255.255.0
println(block.contains(@moonip.Addr::parse("192.0.2.7"))) // true
println(block.hosts().next()) // Some(192.0.2.1)
}The guide walks the whole surface in ten steps; the reference is generated from the interface the compiler emits; the explorer takes blocks apart.