Wrong route for multiple matching host glob patterns

[arrodriguez]

@magiconair @marcosnils @xetorthio
Hello guys :

i am wondering which route fabio selects when we have configure this prefix:

urlprefix-*.edge.foo.com/gizmo, urlprefix-*.foo.com/gizmo

if use api.edge.foo.com in the host header, What is the expect behaviour?
It will use *.edge.foo.com/gizmo or *.foo.com/gizmo ?

I was doing a couple of tests and always select the route * foo.com

Regards!

[marcosnils]

IIUC fabio should match the routes from the most specific to the most generic one. So, in this particular case I'd expect to match the *.edge.foo.com for the hostname api.edge.foo.com

[arrodriguez]

Yes, i would expect the same result, but navigating old issues and doing some testing , the results were this:

• if the host is a complete match, it take precedence over the glob route.

Test:

host: 
api.edge.foo.com/lalala

routes:

urlprefix-api.edge.foo.com/lalala ,  urlprefix-*.foo.com/lalala

• When two or more glob routes are compiting , the most general one is taking precedence over the more specific.

Test

host: 
api.edge.foo.com/lalala

routes:

urlprefix-*.edge.foo.com/lalala ,  urlprefix-*.foo.com/lalala

In this scenario urlprefix-*.foo.com/lalala  matches

Fabio version is v1.5.6.

Regards

[aaronhurt]

Could you see if you can reproduce the same behavior and b the current version? I thought this was covered in a router test case.

[magiconair]

I can't reproduce this. When I add this test to the 1.5.6 codebase it works:

Sun Jun 10 20:25 frank@fancypants ((v1.5.6) *) $ git diff
diff --git a/route/table_test.go b/route/table_test.go
index eb0fdea..7d2da44 100644
--- a/route/table_test.go
+++ b/route/table_test.go
@@ -495,6 +495,7 @@ func TestTableLookup(t *testing.T) {
        route add svc z.abc.com/foo/ http://foo.com:3100
        route add svc *.abc.com/ http://foo.com:4000
        route add svc *.abc.com/foo/ http://foo.com:5000
+       route add svc *.def.abc.com/ http://foo.com:6000
        route add svc xyz.com:80/ https://xyz.com
        `

@@ -530,6 +531,7 @@ func TestTableLookup(t *testing.T) {

                // glob match the host
                {&http.Request{Host: "x.abc.com", URL: mustParse("/")}, "http://foo.com:4000"},
+               {&http.Request{Host: "x.def.abc.com", URL: mustParse("/")}, "http://foo.com:6000"},
                {&http.Request{Host: "y.abc.com", URL: mustParse("/abc")}, "http://foo.com:4000"},
                {&http.Request{Host: "x.abc.com", URL: mustParse("/foo/")}, "http://foo.com:5000"},
                {&http.Request{Host: "y.abc.com", URL: mustParse("/foo/")}, "http://foo.com:5000"},

[magiconair]

Same for 1.5.9 and when I let the test run in a loop.

cd route ; go test -c ; while true ; do route.test -test.run TableLookup ; done

[marcosnils]

@magiconair thanks a lot for taking the time to test this. I haven't checked but in @arrodriguez example there's a path in the URL. Maybe that's causing the issue?

[magiconair]

Hmm, I can reproduce this with the test server.

[magiconair]

# term 1
consul agent -dev

# term 2
cd $GOPATH/src/github.com/fabiolb/fabio/demo/server
go build
./server -prefix '*.edge.foo.com/gizmo' -addr 127.0.0.1:5000

# term 3
cd $GOPATH/src/github.com/fabiolb/fabio/demo/server
./server -prefix '*.foo.com/gizmo' -addr 127.0.0.1:9999

# term 4
cd $GOPATH/src/github.com/fabiolb/fabio
go build
./fabio

# term 5
curl -H 'Host: api.edge.foo.com' http://127.0.0.1:9999/gizmo

The demo server responds with 404 not found which is a bug in the demo server but the request gets routed to the wrong backend.

[magiconair]

Looks like a bug.

[magiconair]

I think I know what is going on. This line doesn't do what I think it does:

https://github.com/fabiolb/fabio/blob/master/route/table.go#L306

The problem is not that fabio does not respect the longer host but that edge < foo. If you replace edge with zzz it "works".

The issue is that domain names have the most significant part at the front whereas the request URIs have the most significant part at the end. [foo.com edge.foo.com] needs to be sorted as [com.foo com.foo.edge] for this to work.

[magiconair]

That's also the reason the test case works since def > abc

[arrodriguez]

@magiconair Thank you for your response. I understand the problem.
How do you think that fabio has to work in this cases ?

while ago i had an issue in some project of firewall rules which uses wildcard host for matching. The difference with fabio is that this project permits the wildcard in any positiion.

The solution were to use "permuterm indexes". (https://nlp.stanford.edu/IR-book/html/htmledition/permuterm-indexes-1.html)

So in my opinion makes sense to rotate de entries in the route table index.

But i dont know if fabio wants this scope.

[magiconair]

Fabio should always go from most specific to least specific when picking a match. However, it also allows a glob pattern anywhere in the host name. *.a.com and *.b.a.com should be sorted as *.b.a.com, *.a.com. However, I am not sure what the order should be for *.a.com and a.*.com. I am OK with leaving this undefined for now. The current implementation - which reverses the strings before sorting - would sort it as *.a.com, a.*.com. ForHost: a.a.com both matches seem equally good. (https://play.golang.org/p/uIMR2rpHOlw)

[arrodriguez]

Yes you are right. Its make sense leaving this like #507