celmatcher: Implement pkix.Name conversion to string

[francislavoie]

For #5491

[ethack]

I believe I have caddy built on this commit.

caddy version
v2.6.5-0.20230415014855-be34eab96247 h1:d0I4nO5yuDmaJz8YnFSxKThUPDpEXcmQ3gDSx/CyxS0=

But still get the same error with the scenario from #5491.

openssl x509 -in certs/user.crt -text | grep Subject | head -1
        Subject: CN = [email protected]

curl -k --cert certs/user.crt --key secrets/user.key https://subjectEndsWith.acme.corp/

No output from curl command, but an error in the logs:

{"level":"error","ts":1681765850.4929817,"logger":"http.matchers.expression","msg":"evaluating expression","error":"internal error: interface conversion: caddyhttp.celPkixName is not traits.Receiver: missing method Receive"}
{"level":"error","ts":1681765850.493016,"logger":"http.log.error","msg":"internal error: interface conversion: caddyhttp.celPkixName is not traits.Receiver: missing method Receive","request":{"remote_ip":"172.23.0.1","remote_port":"44312","client_ip":"172.23.0.1","proto":"HTTP/2.0","method":"GET","host":"subjectEndsWith.acme.corp","uri":"/","headers":{"User-Agent":["curl/7.81.0"],"Accept":["*/*"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"subjectendswith.acme.corp","client_common_name":"[email protected]","client_serial":"284678274866306650542870557902111780363"}},"duration":0.000138086}

[francislavoie]

You would need to explicitly type convert it to a string first I think:

string({http.request.tls.client.san.emails}).exists(email, email == "[email protected]")

Or with dyn as Tristan suggested, maybe:

dyn({http.request.tls.client.san.emails}).exists(email, email == "[email protected]")

[ethack]

Got it. Both string(...) and string(dyn(...)) work. Straight dyn(...) does not. Seems like that's expected so it's just fyi.