Pro opinions plz

proxies.md

Background: The host page proxy

From inside a worker server, the only external hostname is "httpl://host.page"

To reach anything, the worker proxies through the hostpage.

"httpl://host.page/http%3A%2F%2Fexplorer%2F"

(This is why I want the percent-encoding rendering more nicely, but that's another topic.)

Background: The link header's extracted data

When links come back in the Link header, Local.js adds some extracted data.

From
Link: <http://foobar.com/foo>; rel="service"; title="foo"

to
Link: <http://foobar.com/foo>; host_domain="foobar.com"; rel="service"; title="foo"

If it's a global URI ([email protected]!foo.com!123) it also extracts and adds host_user, host_network, host_app, and host_sid. These are the host_* attrs.

They are helpful for navigating the links

agent.follow({ rel: 'gwr.io/chat', host_user: 'pfraze' }) // go to pfraze's chat

But it needs to be extracted from the URI so that the host_* attrs can always be trusted. Otherwise, rando server could do:

Link: <http://foo.com>; host_domain="lies.com"; title="This is totally lies.com not foo.com"

Problem: the proxy fucks up the link header's extracted data

This is how the response from a proxy gets transformed:

From
Link: <httpl://host.page/http%3A%2F%2Fexplorer%2F>; rel="service"; title="Explorer"

to
Link: <httpl://host.page/http%3A%2F%2Fexplorer%2F>; host_domain="host.page"; rel="service"; title="Explorer"

Oh noes, host_domain will always be "host.page". Not very useful that way -- I need to reason about the endpoint, not the proxy.

Because Localjs overwrites all the host_ attributes, the proxy can't override the host_ values.

Proposal 1: have the proxy add "upstream" attrs

From
Link: <httpl://host.page/http%3A%2F%2Fexplorer%2F>; rel="service"; title="Explorer"

to
Link: <httpl://host.page/http%3A%2F%2Fexplorer%2F>; host_domain="host.page"; up1_domain="explorer"; rel="service"; title="Explorer"

Above, that would be up1_domain. It's numbered to account for the possibility of multiple proxies.

Proposal 2: give the proxy special powers

Let the host page proxy override the host_ attributes. This can only work if the proxy is known to be trusted.

Proposal 3: add proxy awareness to Localjs

This means that all proxy URIs need to follow a format that local can predict and pick apart.

Proposal 4: dont let proxies alter the link headers

Instead, preserve the responses and let the client construct proxied URIs using the Via header

Via: HTTPL/0.1 host.page
Link: <httpl://explorer/>; rel="self service", </foo>; rel="item"; id="foo" 

becomes

Link: <httpl://host.page/httpl://explorer/>; host_domain="explorer"; rel="self service", <httpl://host.page/httpl://explorer/foo>; host_domain="explorer"; rel="item"; id="foo" 

Cons:

• Can't distinguish between links which should or should not be proxied
• Enforces only one kind of proxy URI (where the path is the subsequent request)