Report tcp 0 port properly. Fixes #1679

Prefer ip_port

Fix everything

lib/puma/binder.rb

@@ -111,10 +111,11 @@ 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}"
+
+            logger.log "* Listening on tcp://#{uri.host}:#{io.local_address.ip_port}"
           end
 
-          @listeners << [str, io] if io
+          add_to_listeners(str, io)
         when "unix"
           path = "#{uri.host}#{uri.path}".gsub("%20", " ")
 
@@ -149,7 +150,7 @@ def parse(binds, logger)
             logger.log "* Listening on #{str}"
           end
 
-          @listeners << [str, io]
+          add_to_listeners(str, io)
         when "ssl"
           params = Util.parse_query uri.query
           require 'puma/minissl'
@@ -222,7 +223,7 @@ def parse(binds, logger)
             logger.log "* Listening on #{str}"
           end
 
-          @listeners << [str, io] if io
+          add_to_listeners(str,io)
         else
           logger.error "Invalid URI: #{str}"
         end
@@ -273,10 +274,9 @@ def loopback_addresses
     #
     def add_tcp_listener(host, port, optimize_for_latency=true, backlog=1024)
       if host == "localhost"
-        loopback_addresses.each do |addr|
+        return loopback_addresses.map do |addr|
           add_tcp_listener addr, port, optimize_for_latency, backlog
-        end
-        return
+        end.last
       end
 
       host = host[1..-2] if host and host[0..0] == '['
@@ -312,10 +312,9 @@ def add_ssl_listener(host, port, ctx,
       MiniSSL.check
 
       if host == "localhost"
-        loopback_addresses.each do |addr|
+        return loopback_addresses.map do |addr|
           add_ssl_listener addr, port, ctx, optimize_for_latency, backlog
-        end
-        return
+        end.last
       end
 
       host = host[1..-2] if host[0..0] == '['
@@ -413,5 +412,10 @@ def inherit_unix_listener(path, fd)
       s
     end
 
+    def add_to_listeners(str, io)
+      # TODO: It's possible that it's "OK" to add loopback addresses to the listeners
+      # array, but we're not sure. See https://github.com/puma/puma/pull/1786
+      @listeners << [str, io] if io && !io.local_address.ipv4_loopback? && !io.local_address.ipv6_loopback?
+    end
   end
 end

test/test_binder.rb

@@ -95,4 +95,16 @@ 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://localhost:(\d+)!.match(@events.stdout.string)
+
+    port = m[1].to_i
+
+    refute_equal 0, port
+  end
 end