HTTPSRedirectMiddleware should be able to accept optional https port

[mjarosie]

Currently HTTPSRedirectMiddleware redirects to the same port as what HTTP is served from. That'd be great if the redirection target port could be given as an optional parameter.

For example when I run an application with the following configuration:

from starlette.applications import Starlette
from starlette.routing import Route
from starlette.responses import PlainTextResponse
from starlette.middleware import Middleware
from starlette.middleware.httpsredirect import HTTPSRedirectMiddleware

async def homepage(request):
    return PlainTextResponse("Hello world!")

routes = [
    Route("/", homepage)
]

middleware = [
    Middleware(HTTPSRedirectMiddleware)
]

app = Starlette(routes=routes, middleware=middleware, debug=True)

And I run it on hypercorn like this:

hypercorn --certfile ./ssl_certificate.pem --keyfile ./ssl_private_key.pem --bind 0.0.0.0:8000 --insecure-bind 0.0.0.0:80 src/app:app

When I go to http://localhost:80 the application tries to redirect me to https://localhost:80.

There are two workarounds:

• implement your own HTTPSRedirectMiddleware which does handle that logic
• use hypercorn's HTTPToHTTPSRedirectMiddleware, as described in their docs, which is not ideal as it's HTTP server specific (if I wanted to switch to some other server, I'd have to change the application code):

from hypercorn.middleware import HTTPToHTTPSRedirectMiddleware

# ... as above but with `HTTPSRedirectMiddleware` removed.

starlette_app = Starlette(routes=routes, debug=True)

app = HTTPToHTTPSRedirectMiddleware(starlette_app, host="localhost:8000")

I'd be happy to fill in a PR as long as that idea sounds reasonable to others : )