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Split hosts into subdomain, registrant label, and public suffix

Source: R/query.R
suffix_extract.Rd

Split hosts into subdomain, registrant label, and public suffix

Usage

suffix_extract(
  domain,
  section = c("all", "icann", "private"),
  output = c("ascii", "unicode"),
  unknown = c("default", "na"),
  invalid = c("na", "error")
)

Arguments

domain

Character vector of DNS hostnames (not URLs). Each element may be a mixed-case ASCII, Unicode, or A-label hostname, a single label, or a hostname with exactly one terminal root dot. See Input contract.

section

Which rule sections are eligible: "all" (default; ICANN and PRIVATE), "icann", or "private". Section filtering happens before prevailing-rule selection, so "private" does not silently add ICANN rules; a host matching no rule in the section falls through to the implicit default rule unless unknown = "na".

output

"ascii" (default) returns lowercase A-labels; "unicode" decodes them after matching. A terminal root dot is preserved either way.

unknown

"default" (default) applies the spec's implicit * rule, so an unlisted single label is its own public suffix; "na" returns NA when no explicit rule in the selected section matches.

invalid

"na" (default) returns NA for each invalid element without a warning; "error" aborts on the first invalid element, reporting its 1-based index.

Value

A base data.frame with one row per input and columns, in order: input (original, unchanged), host (canonical host in output form), subdomain (labels left of the registrable domain; "" when none), domain (the single registrant label left of the suffix), suffix (the public suffix), and registrable_domain (eTLD+1). domain, subdomain, and registrable_domain are NA when the host is itself a public suffix. If public-suffix resolution is NA, every derived column except input and a successfully normalized host is NA. Zero-length input returns a zero-row frame; all-invalid input keeps one row per input. Root dots are preserved on host, suffix, and registrable_domain only.

Input contract

NA is treated as missing (returns NA), not invalid. Invalid elements include empty or whitespace-only strings, leading or consecutive dots, URL syntax, IPv6 addresses, canonical dotted-decimal IPv4 literals, and labels that fail hostname/IDNA validation. Wrong argument types and non-scalar or unknown option values always abort regardless of invalid.

See also

public_suffix(), public_suffix_rule()

Examples

suffix_extract("www.example.co.uk")
#>               input              host subdomain  domain suffix
#> 1 www.example.co.uk www.example.co.uk       www example  co.uk
#>   registrable_domain
#> 1      example.co.uk
suffix_extract(c("example.com", "com", NA))
#>         input        host subdomain  domain suffix registrable_domain
#> 1 example.com example.com           example    com        example.com
#> 2         com         com      <NA>    <NA>    com               <NA>
#> 3        <NA>        <NA>      <NA>    <NA>   <NA>               <NA>