Network.Wai.Middleware.Static

Serve static files, subject to a policy that can filter or modify incoming URIs. The flow is:

incoming request URI ==> policies ==> exists? ==> respond

If any of the polices fail, or the file doesn't exist, then the middleware gives up and calls the inner application. If the file is found, the middleware chooses a content type based on the file extension and returns the file contents as the response.

Middlewares

static :: Middleware

Serve static files out of the application root (current directory). If file is found, it is streamed to the client and no further middleware is run.

staticPolicy :: Policy -> Middleware

Serve static files subject to a Policy

Policies

data Policy

Take an incoming URI and optionally modify or filter it. The result will be treated as a filepath.

Instances

Monoid Policy

Note: mempty == policy Just (the always accepting policy) mappend == >-> (policy sequencing)

(<|>) :: Policy -> Policy -> Policy infixr 4

Choose between two policies. If the first fails, run the second.

(>->) :: Policy -> Policy -> Policy infixr 5

Sequence two policies. They are run from left to right. (Note: this is mappend)

policy :: (String -> Maybe String) -> Policy

Lift a function into a Policy

predicate :: (String -> Bool) -> Policy

Lift a predicate into a Policy

addBase :: String -> Policy

Add a base path to the URI

staticPolicy (addBase "/home/user/files")

GET "foo/bar" looks for "/home/user/files/foo/bar"

addSlash :: Policy

Add an initial slash to to the URI, if not already present.

staticPolicy addSlash

GET "foo/bar" looks for "/foo/bar"

contains :: String -> Policy

Accept only URIs containing given string

hasPrefix :: String -> Policy

Accept only URIs with given prefix

hasSuffix :: String -> Policy

Accept only URIs with given suffix

noDots :: Policy

Reject URIs containing ".."

only :: [(String, String)] -> Policy

Use URI as the key to an association list, rejecting those not found. The policy result is the matching value.

staticPolicy (only [("foo/bar", "/home/user/files/bar")])

GET "foo/bar" looks for "/home/user/files/bar" GET "baz/bar" doesn't match anything

Utilities

tryPolicy :: Policy -> String -> Maybe String

Run a policy