caddyfile: Fix comma edgecase in address parsing

[francislavoie]

When the site address line looks like foo , bar (i.e. spaces around the , and not simply a comma trailing an address), then it would cause the site address to include an empty space which messes up parsing in subtle ways. This fixes that case.

Closes caddyserver/website#395

Given this Caddyfile:

foo.example.com , example.com , www.example.com {
    respond "foo"
}

Before (for some reason, no host matchers are produced, but it does automate the names):

{"apps":{"http":{"servers":{"srv0":{"listen":[":443"],"routes":[{"handle":[{"body":"foo","handler":"static_response"}]}]}}},"tls":{"certificates":{"automate":["foo.example.com","example.com","www.example.com"]}}}}

After (properly matching the hosts, later resulting in Auto HTTPS automating):

{"apps":{"http":{"servers":{"srv0":{"listen":[":443"],"routes":[{"match":[{"host":["foo.example.com","example.com","www.example.com"]}],"handle":[{"handler":"subroute","routes":[{"handle":[{"body":"foo","handler":"static_response"}]}]}],"terminal":true}]}}}}}

[mholt]

Could we do this better by changing if value[len(value)-1] == ',' { to if value[len(value)-1] == ',' && len(strings.TrimSpace(value)) > 1 { ?

[francislavoie]

No because that would ignore the comma (not trim it) then pass the "contains ," condition, throwing an error. We want to just ignore a bare ,.

--- FAIL: TestParseAll (0.00s)
    caddy/caddyconfig/caddyfile/parse_test.go:611: Test 4: Expected no error, but got: Site addresses cannot contain a comma ',': ',' - put a space after the comma to separate site addresses, at Testfile:1
    caddy/caddyconfig/caddyfile/parse_test.go:615: Test 4: Expected 1 server blocks, got 0

[mholt]

Ah okay. This works then.