Queries the Internet Archive “available” API for the closest
archived snapshot of url and returns its address, or NULL
when nothing is archived. Use it to find an archived copy of a data file
or page that has moved or been removed. C++ backend; supersedes the older
R-level resolver wbsnpurl, which is kept for
the pure-R path and now parses with the package's own JSON codec.
Value
The https snapshot URL (a length-1 character string), or
NULL if none is archived or the lookup failed.
Details
url is only a query parameter of the lookup, never fetched, so a
plain http:// page can be looked up; a local or private address is
still refused. One request is made to https://archive.org/; the
most recent snapshot is asked for (there is no timestamp argument; use
wbsnpurl() for one). Any network
failure, and a URL that was
never archived, give NULL rather than an error. A spinner is drawn
on stderr while waiting, unless options(morie.quiet = TRUE).
Errors: url not a single non-empty string; a local or private
address.
Examples
# Input is validated before any network call:
try(wbsnpnat("")) # empty url -> error
#> Error : `url` must be a single non-empty string
try(wbsnpnat("http://localhost/report.csv"))
#> Error : url points at a local or private address ('http://localhost/report.csv'): refused (a single-label name is not a public host (localhost))
if (FALSE) { # interactive()
# needs the network; any network failure returns NULL rather than erroring.
# Closest archived snapshot of a live page (or NULL if none archived).
wbsnpnat("https://www.r-project.org/")
# A shorter timeout for a quick lookup.
wbsnpnat("https://cloud.r-project.org/", tmout = 10)
# A never-archived URL returns NULL rather than erroring.
wbsnpnat("https://example.invalid/never-archived")
}