AlinsRan opened a new pull request, #13781:
URL: https://github.com/apache/apisix/pull/13781
### Description
Hostnames are case-insensitive, and route matching runs against `$host`,
which nginx always lowercases (`ngx_http_validate_host()`). `apisix/router.lua`
normalizes this on the route object:
```lua
if route.value.host then
route.value.host = str_lower(route.value.host)
elseif route.value.hosts then
for i, v in ipairs(route.value.hosts) do
route.value.hosts[i] = str_lower(v)
end
end
```
`apisix/http/service.lua` has no equivalent, so `service.hosts` is stored
verbatim. `radixtree_host_uri` — the default router — builds its host buckets
itself, keyed on the raw reversed host string:
```lua
-- apisix/http/router/radixtree_host_uri.lua
for i, host in ipairs(hosts) do
local host_rev = host:reverse()
```
A service host containing an uppercase character therefore ends up in a
bucket keyed on e.g. `moc.elpmaxe.esaCdexiM`, which the lowercase `$host` can
never reach. The route falls through to `only_uri_router`, and if nothing
host-agnostic matches, the request 404s — for every path and every casing of
the request `Host`, so the host is silently unroutable.
`radixtree_uri` is not affected, because it passes `hosts` to
lua-resty-radixtree, which lowercases on both the config side and the request
side.
Reproduced on 3.16.0 in standalone mode, with `service.hosts:
["MixedCase.example.com"]` and a route with no `hosts` of its own:
| request `Host` | `radixtree_host_uri` (default) | `radixtree_uri` | after
this patch |
| --- | --- | --- | --- |
| `MixedCase.example.com` | 404 | 200 | 200 |
| `mixedcase.example.com` | 404 | 200 | 200 |
| `MIXEDCASE.EXAMPLE.COM` | 404 | 200 | 200 |
This patch lowercases the hosts in the service `filter()`, mirroring what
`router.lua` already does for routes.
Found via apache/apisix-ingress-controller#2822: the controller carries the
host constraint on the service object, so an ingress route with an uppercase
hostname is unroutable.
#### Which issue(s) this PR fixes:
N/A
### Checklist
- [x] I have explained the need for this PR and the problem it solves
- [x] I have explained the changes or the new features added to this PR
- [x] I have added tests corresponding to this change
- [ ] I have updated the documentation to reflect this change
- [x] I have verified that this change is backward compatible (If not,
please discuss on the [APISIX mailing
list](https://github.com/apache/apisix/tree/master#community) first)
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