silly.net.addr

silly.net.addr provides address parsing and joining helpers for host:port strings.

Module Import

local addr = require "silly.net.addr"

Parsing Rules

Input parsing accepts these forms:

• IPv4: "127.0.0.1:8080"
• IPv6: "[::1]:8080" (brackets required to disambiguate the port)
• Empty host: ":8080" (listen on all addresses)
• Domain: "example.com:80"
• Host only, no port: "example.com"

For non-bracketed input, the first : is used as the host/port separator. Unbracketed IPv6 literals (e.g. "::1:8080") are therefore parsed as host "" and port ":1:8080" — always wrap IPv6 hosts in [].

For output, prefer addr.join() which wraps IPv6 hosts in [] automatically.

Notes:

• Empty host (e.g. ":8080" or "[]:8080") returns host = nil.
• Input without a port (e.g. "example.com") returns port = nil.

Functions

addr.parse(addr)

Parse a host:port string.

Parameters:

• addr (string): address string

Returns:

• host (string|nil)
• port (string|nil)

Example:

local host, port = addr.parse("127.0.0.1:8080")
-- host = "127.0.0.1", port = "8080"

local host2, port2 = addr.parse("[::1]:443")
-- host2 = "::1", port2 = "443"

local host3, port3 = addr.parse("example.com")
-- host3 = "example.com", port3 = nil

addr.join(host, port)

Join host and port into a normalized address string. Hosts containing : (i.e. IPv6 literals) are wrapped in [] automatically.

Parameters:

• host (string): host
• port (string): port

Returns:

• addr (string)

Example:

addr.join("127.0.0.1", "8080")  -- "127.0.0.1:8080"
addr.join("::1", "443")         -- "[::1]:443"
addr.join("", "8080")           -- ":8080"

addr.iptype(host)

Classify host as an IP literal.

Parameters:

• host (string): host string

Returns:

• integer: 4 for a valid IPv4 literal, 6 for a valid IPv6 literal, 0 otherwise (e.g. domain names)

Uses inet_pton internally, so the classification matches what the OS considers a valid IP address.

addr.isv4(host)

Returns true iff addr.iptype(host) == 4 — i.e. host is a syntactically valid IPv4 literal.

addr.isv6(host)

Returns true iff addr.iptype(host) == 6 — i.e. host is a syntactically valid IPv6 literal. A string that merely contains : is not enough; inet_pton must accept it.

addr.ishost(host)

Returns true iff host is non-empty and addr.iptype(host) == 0 — i.e. it is neither a valid IPv4 nor a valid IPv6 literal. Typical callers use this to decide whether a DNS lookup is needed.