How to determine if you have an internet connection in R

Question

Sometimes I need to download data from the internet. On occasions this has failed either because the website is down or because my computer has lost its internet connection.

Answer 1

The curl package has a function has_internet which tests by performing a nslookup:

curl::has_internet
## function(){
##    !is.null(nslookup("google.com", error = FALSE))
## }

Testing DNS is faster and may be more reliable than retrieving a URL because the latter might fail for unrelated reasons (e.g. firewall, server down, etc).

Answer 2

Do it with just two lines of code:

install.packages('pingr')
pingr::is_online()

Answer 3

As the function above from eyjo

havingIP <- function() {
 if (.Platform$OS.type == "windows") {
   ipmessage <- system("ipconfig", intern = TRUE)
 } else {
   ipmessage <- system("ifconfig", intern = TRUE)
 }
 validIP <- "((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)[.]){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)"
 any(grep(validIP, ipmessage))
}

also returns true for localhost ip "127.0.0.1" it needs to be removed to prevent false positives. For example as shown below:

 havingIP <- function() {
 if (.Platform$OS.type == "windows") {
   ipmessage <- system("ipconfig", intern = TRUE)
 } else {
   ipmessage <- system("ifconfig", intern = TRUE)
 }
 validIP <- "((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)[.]){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)"
 any(grep(validIP, ipmessage[-grep("127.0.0.1", ipmessage)]))
}

But even better would be a solution that prevents localhosts by modifying the regex of validIP.

Answer 4

A dirty work around would be using RCurl::getURL function.

if (is.character(getURL("www.google.com"))) {
    out <- TRUE
} else {
    out <- FALSE
}

Answer 5

Here is an attempt at parsing the output from ipconfig/ifconfig, as suggested by Spacedman.

havingIP <- function() {
  if (.Platform$OS.type == "windows") {
    ipmessage <- system("ipconfig", intern = TRUE)
  } else {
    ipmessage <- system("ifconfig", intern = TRUE)
  }
  validIP <- "((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)[.]){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)"
  any(grep(validIP, ipmessage))
}

With a simple TRUE/FALSE output

> havingIP()
[1] TRUE

Answer 6

Bioconductor's Biobase package has a function for testing internet connection.

Biobase::testBioCConnection()

Below is a heavily modified version of this function for testing ability to read lines from a URL.

can_internet <- function(url = "http://www.google.com") {

    # test the http capabilities of the current R build
    if (!capabilities(what = "http/ftp")) return(FALSE)

    # test connection by trying to read first line of url
    test <- try(suppressWarnings(readLines(url, n = 1)), silent = TRUE)

    # return FALSE if test inherits 'try-error' class
    !inherits(test, "try-error")
}

can_internet()