From 601460c0b3f8755f72dcf658283c63c2f6eb1b76 Mon Sep 17 00:00:00 2001
From: Richard Hansen <rhansen@rhansen.org>
Date: Mon, 3 Aug 2020 12:51:46 -0400
Subject: [PATCH] Turn `if-skip` into a no-op and mark it as deprecated

There is no way the user can meaningfully set `if-skip` because the
user doesn't have control over how ddclient reads an interface's
settings (ddclient could theoretically run `ip addr show`, run
`ifconfig`, read a file in `/dev`, make a system call, use a Perl
library, etc.).
---
 ChangeLog.md |  1 +
 ddclient.in  | 19 +++++++++----------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/ChangeLog.md b/ChangeLog.md
index 3e6e994..0d53025 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -58,6 +58,7 @@ repository history](https://github.com/ddclient/ddclient/commits/master).
     Rather than rely on the default, users should explicitly set the `use`
     option.
   * The `fw-banlocal` option is deprecated and no longer does anything.
+  * The `if-skip` option is deprecated and no longer does anything.
   * The default server for the `dslreports1` protocol changed from
     `members.dyndns.org` to `www.dslreports.com`.
   * Removed support for defunct dtdns service
diff --git a/ddclient.in b/ddclient.in
index be005a8..a78677c 100755
--- a/ddclient.in
+++ b/ddclient.in
@@ -380,7 +380,6 @@ my %variables = (
         'use'                 => setv(T_USE,   0, 0, 'ip',                 undef),
         'ip'                  => setv(T_IP,    0, 0, undef,                undef),
         'if'                  => setv(T_IF,    0, 0, 'ppp0',               undef),
-        'if-skip'             => setv(T_STRING,1, 0, '',                   undef),
         'web'                 => setv(T_STRING,0, 0, 'dyndns',             undef),
         'web-skip'            => setv(T_STRING,1, 0, '',                   undef),
         'fw'                  => setv(T_ANY,   0, 0, '',                   undef),
@@ -421,7 +420,6 @@ my %variables = (
 
         'use'                 => setv(T_USE,   0, 0, 'ip',                 undef),
         'if'                  => setv(T_IF,    0, 0, 'ppp0',               undef),
-        'if-skip'             => setv(T_STRING,0, 0, '',                   undef),
         'web'                 => setv(T_STRING,0, 0, 'dyndns',             undef),
         'web-skip'            => setv(T_STRING,0, 0, '',                   undef),
         'fw'                  => setv(T_ANY,   0, 0, '',                   undef),
@@ -756,7 +754,9 @@ $variables{'merged'} = {
 
 # This will hold the processed args.
 my %opt = ();
-$opt{'fw-banlocal'} = sub { warning("'-fw-banlocal' is deprecated and does nothing") };
+my $deprecated_handler = sub { warning("'-$_[0]' is deprecated and does nothing"); };
+$opt{'fw-banlocal'} = $deprecated_handler;
+$opt{'if-skip'} = $deprecated_handler;
 
 my @opt = (
     "usage: ${program} [options]",
@@ -778,7 +778,6 @@ my @opt = (
     "",
     "  Options that apply to 'use=if':",
     ["if",           "=s", "-if <interface>       : obtain IP address from <interface>"],
-    ["if-skip",      "=s", "-if-skip <pattern>    : skip any IP addresses before <pattern> in the output of 'ip address show dev <interface>' (or 'ifconfig <interface>')"],
     "",
     "  Options that apply to 'use=web':",
     ["web",          "=s", "-web <service>|<url>  : obtain IP address from a web-based IP discovery service, either a known <service> or a custom <url>"],
@@ -820,6 +819,7 @@ my @opt = (
     ["postscript",   "",   "-postscript           : script to run after updating ddclient, has new IP as param"],
     ["query",        "!",  "-{no}query            : print {no} ip addresses and exit"],
     ["fw-banlocal",  "!",  ""], ## deprecated
+    ["if-skip",      "=s", ""], ## deprecated
     ["test",         "!",  ""], ## hidden
     ["geturl",       "=s", ""], ## hidden
     "",
@@ -1113,8 +1113,8 @@ sub parse_assignments {
         (my $name, my $value, $rest) = parse_assignment($rest);
         $rest =~ s/^[,\s]+//;
         return ($rest, %variables) if !defined($name);
-        if ($name eq 'fw-banlocal') {
-            warning("'fw-banlocal' is deprecated and does nothing");
+        if ($name eq 'fw-banlocal' || $name eq 'if-skip') {
+            warning("'$name' is deprecated and does nothing");
             next;
         }
         $variables{$name} = $value;
@@ -1348,8 +1348,8 @@ sub init_config {
         my %options = ();
         foreach my $opt (split_by_comma($opt{'options'})) {
             my ($name, $var) = split /\s*=\s*/, $opt;
-            if ($name eq 'fw-banlocal') {
-                warning("'fw-banlocal' is deprecated and does nothing");
+            if ($name eq 'fw-banlocal' || $name eq 'if-skip') {
+                warning("'$name' is deprecated and does nothing");
                 next;
             }
             $options{$name} = $var;
@@ -2215,7 +2215,6 @@ sub get_ip {
         $arg = 'ip';
 
     } elsif ($use eq 'if') {
-        $skip = opt('if-skip', $h) // '';
         $reply = `command -v ip >/dev/null && ip address show dev $arg`;
         $reply = `command -v ifconfig >/dev/null && ifconfig $arg` if $?;
         $reply = '' if $?;
@@ -2307,7 +2306,7 @@ sub get_ip {
     if (!defined $reply) {
         $reply = '';
     }
-    if ($skip) {
+    if (($skip // '') ne '') {
         $skip  =~ s/ /\\s/is;
         $reply =~ s/^.*?${skip}//is;
     }