From 36d8b511b37ec981700330ccc3dd795a8b708989 Mon Sep 17 00:00:00 2001
From: David Kerr <david@kerr.net>
Date: Tue, 30 Jun 2020 13:29:10 -0400
Subject: [PATCH] Move `un_zero_pad` into `extract_ipv4`, `extract_ipv6`

This also causes `is_ipv4` to reject IPv4 addresses with leading
zeros.
---
 ddclient.in | 51 ++++++++++++++++-----------------------------------
 1 file changed, 16 insertions(+), 35 deletions(-)

diff --git a/ddclient.in b/ddclient.in
index 9883d31..90a2f96 100755
--- a/ddclient.in
+++ b/ddclient.in
@@ -2181,26 +2181,7 @@ sub geturl {
     $reply =~ s/\r//g if defined $reply;
     return $reply;
 }
-######################################################################
-## un_zero_pad
-######################################################################
-sub un_zero_pad {
-    my $in_str  = shift(@_);
-    my @out_str = ();
 
-    if ($in_str eq '0.0.0.0') {
-        return $in_str;
-    }
-
-    foreach my $block (split /\./, $in_str) {
-        $block =~ s/^0+//;
-        if ($block eq '') {
-            $block = '0';
-        }
-        push @out_str, $block;
-    }
-    return join('.', @out_str);
-}
 ######################################################################
 ## get_ip
 ######################################################################
@@ -2312,15 +2293,8 @@ sub get_ip {
         $skip  =~ s/ /\\s/is;
         $reply =~ s/^.*?${skip}//is;
     }
-    if (defined($ip)) {
-        # no need to parse $reply
-    } elsif ($ip = extract_ipv4($reply)) {
-        $ip = un_zero_pad($ip);
-    } elsif ($ip = extract_ipv6($reply)) {
-        $ip = un_zero_pad($ip);
-    } else {
-        warning("found neither ipv4 nor ipv6 address");
-    }
+    $ip //= extract_ipv4($reply) // extract_ipv6($reply);
+    warning("found neither IPv4 nor IPv6 address") if !defined($ip);
     if ($use ne 'ip' && ($ip // '') eq '0.0.0.0') {
         $ip = undef;
     }
@@ -2330,8 +2304,9 @@ sub get_ip {
 }
 
 ######################################################################
-## is_ipv4() validates if string is valid IPv4 address and only
-## a valid IPv4 address (no preceding or trailing spaces/characters)
+## is_ipv4() validates if string is valid IPv4 address and only a
+## valid address with no preceding or trailing spaces/characters
+## and no embedded leading zeros.
 ######################################################################
 sub is_ipv4 {
     my ($value) = @_;
@@ -2339,11 +2314,14 @@ sub is_ipv4 {
 }
 
 ######################################################################
-## extract_ipv4() extracts the first valid IPv4 address from the given string
+## extract_ipv4() extracts the first valid IPv4 address from given string.
+## Accepts leading zeros in the address but removes them in returned value
 ######################################################################
 sub extract_ipv4 {
-    (shift // '') =~ /\b((?:(?<octet>25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?&octet))\b/a;
-    return $1;
+    (shift // '') =~ /\b((?:(?<octet>25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?&octet))\b/a
+        or return undef;
+    (my $ip = $1) =~ s/\b0+\B//g; ## remove embedded leading zeros
+    return $ip;
 }
 
 ######################################################################
@@ -2352,11 +2330,13 @@ sub extract_ipv4 {
 ######################################################################
 sub is_ipv6 {
     my ($value) = @_;
-    return (length($value // '') != 0) && ((extract_ipv6($value) // '') eq $value);
+    return (length($value // '') != 0) &&
+        ((extract_ipv6($value) // '') eq (($value =~ s/\b0+\B//g) ? $value : $value));
 }
 
 ######################################################################
-## extract_ipv6() extracts the first valid IPv6 address from the given string
+## extract_ipv6() extracts the first valid IPv6 address from the given string.
+## Accepts leading zeros in the address but removes them in returned value.
 ######################################################################
 sub extract_ipv6 {
     my $content = shift;
@@ -2378,6 +2358,7 @@ sub extract_ipv6 {
                 next
             }
         }
+        $parsed =~ s/\b0+\B//g; ## remove embedded leading zeros
         return $parsed;
     }
     return;