mosh: implement --local option for use without ssh

man/mosh.1

@@ -165,6 +165,12 @@ Do not send the \fBsmcup\fP initialization string and \fBrmcup\fP
 deinitialization string to the client's terminal. On many terminals
 this disables alternate screen mode.
 
+.TP
+.B \-\-local
+Invoke \fBmosh-server\fP locally, without using \fBssh\fP.  This
+option requires the \fBhost\fP argument to be a local, numeric
+IPv4/IPv6 address.  This option is useful for testing.
+
 .SH ESCAPE SEQUENCES
 
 The default escape character used by Mosh is ASCII RS (decimal 30).

scripts/mosh.pl

@@ -51,6 +51,8 @@ my $ssh = 'ssh';
 
 my $term_init = 1;
 
+my $localhost = undef;
+
 my $help = undef;
 my $version = undef;
 
@@ -81,6 +83,8 @@ qq{Usage: $0 [options] [--] [user@]host [command...]
 
         --no-init            do not send terminal initialization string
 
+        --local              run mosh-server locally without using ssh
+
         --help               this message
         --version            version and copyright information
 
@@ -117,6 +121,7 @@ GetOptions( 'client=s' => \$client,
 	    'p=s' => \$port_request,
 	    'ssh=s' => \$ssh,
 	    'init!' => \$term_init,
+	    'local' => \$localhost,
 	    'help' => \$help,
 	    'version' => \$version,
 	    'fake-proxy!' => \my $fake_proxy,
@@ -157,20 +162,34 @@ if ( defined $port_request ) {
 
 delete $ENV{ 'MOSH_PREDICTION_DISPLAY' };
 
+my $userhost;
+my @command;
 my @bind_arguments;
-if ( not defined $bind_ip or $bind_ip =~ m{^ssh$}i ) {
+
+if ( ! defined $fake_proxy ) {
+  if ( scalar @ARGV < 1 ) {
+    die $usage;
+  }
+  $userhost = shift;
+  @command = @ARGV;
+  if ( not defined $bind_ip or $bind_ip =~ m{^ssh$}i ) {
+    if ( not defined $localhost ) {
       push @bind_arguments, '-s';
-} elsif ( $bind_ip =~ m{^any$}i ) {
+    } else {
+      push @bind_arguments, ('-i', "$userhost");
+    }
+  } elsif ( $bind_ip =~ m{^any$}i ) {
     # do nothing
-} elsif ( $bind_ip =~ m{^[0-9\.]+$} ) {
+  } elsif ( $bind_ip =~ m{^[0-9\.]+$} ) {
     push @bind_arguments, ('-i', "$bind_ip");
-} else {
+  } else {
     print STDERR qq{$0: Unknown server binding option: $bind_ip\n};
 
     die $usage;
-}
+  }
+} else {
+  my ( $host, $port ) = @ARGV;
 
-if ( defined $fake_proxy ) {
   use Errno qw(EINTR);
   my $have_ipv6 = eval {
       require IO::Socket::IP;
@@ -189,8 +208,6 @@ if ( defined $fake_proxy ) {
 	}
   }
 
-  my ( $host, $port ) = @ARGV;
-
   # Resolve hostname and connect
   my $afstr = 'AF_' . uc( $family );
   my $af = eval { IO::Socket->$afstr } or die "$0: Invalid family $family\n";
@@ -231,13 +248,6 @@ if ( defined $fake_proxy ) {
   exit;
 }
 
-if ( scalar @ARGV < 1 ) {
-  die $usage;
-}
-
-my $userhost = shift;
-my @command = @ARGV;
-
 # Count colors
 open COLORCOUNT, '-|', $client, ('-c') or die "Can't count colors: $!\n";
 my $colors = "";
@@ -278,6 +288,13 @@ if ( $pid == 0 ) { # child
     push @server, '--', @command;
   }
 
+  if ( defined( $localhost )) {
+    delete $ENV{ 'SSH_CONNECTION' };
+    chdir; # $HOME
+    print "MOSH IP ${userhost}\n";
+    exec( $server, @server );
+    die "Cannot exec $server: $!\n";
+  }
   my $quoted_self = shell_quote( $0, "--family=$family" );
   exec "$ssh " . shell_quote( '-S', 'none', '-o', "ProxyCommand=$quoted_self --fake-proxy -- %h %p", '-n', '-tt', $userhost, '--', "$server " . shell_quote( @server ) );
   die "Cannot exec ssh: $!\n";