Report tcp 0 port properly. Fixes #1679

Bonus feature: we now log all localhost addresses that we're bound to,
including ipv6 ones.

lib/puma/binder.rb

@@ -111,7 +111,16 @@ def parse(binds, logger)
             bak = params.fetch('backlog', 1024).to_i
 
             io = add_tcp_listener uri.host, uri.port, opt, bak
-            logger.log "* Listening on #{str}"
+
+            @ios.each do |i|
+              addr = if i.local_address.ipv6?
+                "[#{i.local_address.ip_unpack[0]}]:#{i.local_address.ip_unpack[1]}"
+              else
+                i.local_address.ip_unpack.join(':')
+              end
+
+              logger.log "* Listening on tcp://#{addr}"
+            end
           end
 
           @listeners << [str, io] if io

test/test_binder.rb

@@ -95,4 +95,24 @@ def test_binder_parses_tlsv1_1_enabled
 
     refute ssl_context_for_binder(@binder).no_tlsv1_1
   end
+
+  def test_correct_zero_port
+    @events = Puma::Events.strings
+    @binder = Puma::Binder.new(@events)
+    @binder.parse(["tcp://localhost:0"], @events)
+
+    m = %r!tcp://127.0.0.1:(\d+)!.match(@events.stdout.string)
+    port = m[1].to_i
+
+    refute_equal 0, port
+  end
+
+  def test_logs_all_localhost_bindings
+    @events = Puma::Events.strings
+    @binder = Puma::Binder.new(@events)
+    @binder.parse(["tcp://localhost:0"], @events)
+
+    assert_match %r!tcp://127.0.0.1:(\d+)!, @events.stdout.string
+    assert_match %r!tcp://\[::1\]:(\d+)!, @events.stdout.string
+  end
 end