skip: kludgy SCION browser support #181

matzf · 2021-01-29T22:01:58Z

skip (SCION kludge in prowsers, also "ship" in many languages and so fitting with the lighthouse/beacon scheme ⛵) is a poor man's browser integration for SCION.

skip uses a Proxy auto-config file to forward all requests that are go to a SCION destination to a proxy server, running as a (native) binary on the localhost. As this mechanism does not let us support a separate protocol identifier nor allow looking up whether a name refers to a SCION address, we identify SCION addresses as either:

the host name of a SCION host with an appended pseudo-TLD .scion, e.g. http://www.scionlab.org.scion, or
a mangled SCION address in the form <ISD>-<AS id with underscores>-<host>, e.g. http://17-ffaa_0_1101-129.132.121.164/

To make links and redirects work as intended, i.e. keep using SCION, the proxy replaces matching URLs in the response with these "munged" addresses.

Limitations:

Chrome does not appear to honor the PAC (WPAD) configuration, even when it reads it. Not sure why.
Does not support HTTPS
Does not support WebSockets (HTTP CONNECT) method
Does not allow specifiying the protocol (e.g. as scion+http://www.scionlab.org) but instead uses a kludgy pseudo-TLD to
identify SCION hosts.

Obviously this is not great, but hey, it's a start. Some inspiration for how to to build something more advanced can be found in this extensions for the gopher protocol, OverbiteNX.

Also in this PR:

use the gorilla/handlers library as logging middleware in HTTP servers, in the new skip proxy server as well as in _examples/shttp/fileserver.

This change is

Add a local web-proxy and a proxy auto-config script to act as a poor man's SCION browser support. Please see skip/README.md for details. Also, use the gorilla/handlers library as logging middleware in HTTP servers, in the new skip proxy server as well as in _examples/shttp/fileserver.

marcfrei · 2021-01-30T08:16:09Z

skip/README.md, line 8 at r1 (raw file):

that go to

?

marcfrei · 2021-01-30T08:20:29Z

skip/README.md, line 9 at r1 (raw file):

skip uses a [Proxy auto-config](https://en.wikipedia.org/wiki/Proxy_auto-config) file
to forward all requests that are go to a SCION destination to a proxy server,
running as a (native) binary on the localhost.

Or just on localhost?

marcfrei · 2021-01-30T08:23:33Z

skip/main.go, line 55 at r1 (raw file):

}

type ProxyHandler struct {

Why is this type exported?

marcfrei · 2021-01-30T08:32:33Z

skip/main.go, line 89 at r1 (raw file):

	parts := mungedScionAddr.FindStringSubmatch(host)
	if parts != nil {
		// directly apply mangling as inMangleSCIONAddr

"as in shttp.MangleSCIONAddrURL" or "as in appnet.MangleSCIONAddr"?

marcfrei · 2021-01-30T08:33:03Z

skip/main.go, line 60 at r1 (raw file):

func (h *ProxyHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {

Empty line?

marcfrei · 2021-01-30T08:34:46Z

skip/main.go, line 1 at r1 (raw file):

// Copyright 2020 ETH Zurich

When do we usually bump the copyright notices to the next year?

marcfrei · 2021-01-30T08:36:52Z

skip/README.md, line 1 at r1 (raw file):

# skip

Do we still want to maintain the new invariant that every app also gets a short section in the main README.md?

marcfrei · 2021-01-30T08:39:12Z

Cool idea, i like how little code it took to implement it.

marcfrei

Reviewable status: complete! 1 of 1 LGTMs obtained

matzf

Reviewable status: 0 of 8 files reviewed, 7 unresolved discussions / 0 of 1 LGTMs obtained, and 1 stale / 0 of 1 approvals obtained

skip/main.go, line 1 at r1 (raw file):