IP address or not?

Question

Your network scanning tool is annoyingly picky about input, and immediately crashes if you feed it an IPv4 address that contains improper characters or isn't properly formatted.

An IPv4 address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255.

We need to write a tool to pre-validate the input to avoid those crashes, and our specific tool is picky: A valid format will look like a.b.c.d where a, b, c and d:

• Can be a 0 or a natural number with no leading zeros.
• Should be between 0 - 255 (inclusive).
• Should not contain special symbols like +, -, ,, and others.
• Should be decimal (base 10)

Input: A string

Output: Truthy or Falsey value (arbitrary values also accepted)

Test Cases:

Input            |  Output  |  Reason
                 |          |
- 1.160.10.240   |  true    |
- 192.001.32.47  |  false   |  (leading zeros present)
- 1.2.3.         |  false   |  (only three digits)
- 1.2.3          |  false   |  (only three digits)
- 0.00.10.255    |  false   |  (leading zeros present)
- 1.2.$.4        |  false   |  (only three digits and a special symbol present)
- 255.160.0.34   |  true    |
- .1.1.1         |  false   |  (only three digits)
- 1..1.1.1       |  false   |  (more than three periods)
- 1.1.1.-0       |  false   |  (special symbol present)
- .1.1.+1        |  false   |  (special symbol present)
- 1 1 1 1        |  false   |  (no periods)
- 1              |  false   |  (only one digit)
- 10.300.4.0     |  false   |  (value over 255)
- 10.4F.10.99    |  false   |  (invalid characters)
- fruit loops    |  false   |  (umm...)
- 1.2.3.4.5      |  false   |  (too many periods/numbers)
- 0.0.0.0        |  true    |
- 0.0 0.0.       |  false   |  (periods misplaced)
- 1.23..4        |  false   |  (a typo of 1.2.3.4)
- 1:1:1:1:1:1:1:1|  false   |  (an IPv6 address, not IPv4)

This is code-golf, so fewest bytes will win!

Note for the users - if anyone wants to add some test-cases, they're welcomed (by suggesting an edit).

Answer 1

JavaScript, 89 bytes

(_,r=`(${[...Array(256).keys()].join`|`})`)=>RegExp(`^${(r+'\\.').repeat(3)+r}$`).test(_)

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Create RegExp capture groups from indexes of an array having length 256 for range 0-255 joined with | and followed by escaped . character (^(0|1...|255)\.(0|1...|255)\.(0|1...|255)\.(0|1...|255)$) repeated 3 times closing with joined array followed by $ to match end of string, return true or false result of input passed to RegExp.prototype.test().

Answer 2

R, 59 bytes

Passes special cases not in test with periods at start/end

function(s)length(a<-scan(,t=s,s,,,"."))==4&all(a%in%0:255)

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Answer 3

C (gcc), 287 197 bytes

#import<regex.h>
g;f(char*s){regex_t r;g=regcomp(&r,"^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$",1);g=regexec(&r,s,0,0,0);return !g;}

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Thanks to Logern for the big save !

Answer 4

Ruby, 123 107 bytes

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a=gets.chomp
e=a.split'.'
(p 0;exit)if(e.map(&:to_i).join'.')!=a
p(e.all?{|i|(0..255)===i.to_i}&&e.size==4)

This could definitely be shorter, probably with a regex of some sort, but I wanted to do it without a regex.

Thanks to MegaTom for Array#all?

0 or false is falsy; true is truthy.

Explanation:

The input is taken from stdin. It's split into an array of the numbers (as strings) on the periods.

If the array isn't the same as it is with the elements converted to numbers and back to strings, the program outputs 0 and exits. This eliminates cases with leading zeros and illegal characters.

The array is converted to an array of true/false values representing whether the value is between 0 and 255, inclusive.

true is outputted if the array is only true values, meaning that all the numbers were between 0 and 255, and only if it has exactly 4 elements, meaning that there were 4 original numbers. false is outputted otherwise, meaning invalid numbers (higher than 255) or too many numbers.

Answer 5

APL(NARS), 45 chars

{'...'≢⍵∼⎕D:0⋄4≠+/255≥⍎¨a←⍵⊂⍨⍵≠'.':0⋄a≡⍕¨⍎¨a}

test

  f←{'...'≢⍵∼⎕D:0⋄4≠+/255≥⍎¨a←⍵⊂⍨⍵≠'.':0⋄a≡⍕¨⍎¨a}  
  f '1.160.10.240'   
1
  f '192.001.32.47' 
0
  f '1.2.3.'
0
  f '1.2.3'
0

Answer 6

Batch, 53 bytes

@(ping -4 %1&echo g 255.255.255.255 w)|find/c"g %1 w"

Disconnect your Internet connection first to avoid the standard loophole.

I can't find information on how to avoid ^".

Answer 7

APL(NARS) 50 chars, 100 bytes

{'...'≢⍵∼⎕D:0⋄4≠≢w←⍵⊂⍨⍵≠'.':0⋄w≢⍕¨m←⍎¨w:0⋄256>⌈/m}

test:

  p←{'...'≢⍵∼⎕D:0⋄4≠≢w←⍵⊂⍨⍵≠'.':0⋄w≢⍕¨m←⍎¨w:0⋄256>⌈/m}
  {⍞←'[',⍵,'=',(p ⍵),']'⋄⍬}¨a 
[1.160.10.240= 1 ][192.001.32.47= 0 ][1.2.3.= 0 ][0.00.10.255= 0 ][1.2.$.4= 0 ][255.160.0.34= 1 ][.1.1.1= 0 ][1..1.1.1= 0 ][1.1.1.-0= 0 ][.1.1.+1= 0 ][1 1 1 1= 0 ][1= 0 ][10.300.4.0= 0 ][10.4F.10.99= 0 ][fruit loops= 0 ][1.2.3.4.5= 0 ][0.0.0.0= 1 ][0.0 0.0.= 0 ][1.23..4= 0 ][1:1:1:1:1:1:1:1= 0 ]  

Answer 8

Scala, 87 bytes

A port of @Olivier Grégoire's answer.

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val f:String=>Boolean=s=>("." + s).matches("(\\.(25[0-5]|(2[0-4]|1\\d|[1-9])?\\d)){4}")

Answer 9

Thunno 2, 15 bytes

'./Ẋl4=ɠL€ṘxƇp&

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Explanation

'./Ẋl4=ɠL€ṘxƇp&  '# Implicit input
'./              '# Split the input on "."s
   Ẋ              # Store this in x without popping
    l4=           # Check if the length equals 4
       ɠL         # Push the range [0..255]
         €Ṙ       # Convert each to a string
           xƇp    # Check if each of the values in x
                  # is in this list of strings
                  # (NOTE: this checks three things at once:
                  #   1. all the parts are numbers
                  #   2. all of them are in the range [0..255]
                  #   3. none of them have leading zeros)
              &   # Check if both things are true
                  # Implicit output

Answer 10

Go, 81 bytes

import."net/netip"
func f(s string)bool{a,e:=ParseAddr(s)
return e==nil&&a.Is4()}

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Uses the net/netip package from the standard library.

Go, 119 bytes

import."regexp"
func f(s string)bool{return MustCompile(`^(\.(25[0-5]|(2[0-4]|1\d|[1-9])?\d)){4}$`).MatchString("."+s)}

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Using the regex from @Olivier Grégoire's post.

Answer 11

PHP, 27 26 24 Bytes

<?=+!!ip2long($argv[1]);

Based on @rexkogitans and @nwellnhof solutions Fails for 0.0.0.0 because PHP internal function 0.0.0.0 is not considered a valid IP address Try it!