via header received-by: os.hostname() vs incoming request host

[icyitscold]

I've noticed that os.hostname() is used to populate the via header's "received-by" section rather than the incoming request url host domain, port. I might be misinterpreting the spec here but I thought the intent of via was to specify the host dns name used to reach the proxy server rather than proxy host machine name.

Consider the following scenario:

I have two dns names pointing to my node webserver which uses node-proxy-middleware

• customer1.webserver.com -> my-webserver-ip
• customer2.webserver.com -> my-webserver-ip

if my-webserver-ip uses proxy-middleware to proxy "/api" to "http://my-appserver/api", then my-appserver should be able to use the via header to figure out if the request came via customer1.webserver.com or customer2.webserver.com.

I understand that the preserveHost flag can be used but becoming blind to the proxy shouldn't be necessary.

I can create a PR for this if desired.

[pavel]

From spec:

The received-by field is normally the host and optional port number of a recipient server or client
that subsequently forwarded the message.

This means received-by is the machine, that does forwarding/redirect, which is a proxy's machine,
os.hostname() is correct here.

To see the originating request chain (the case you've described with customer1.webserver.com) X-Forwarded-For is used.